1 /*
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   3  *
   4  * The contents of this file are subject to the terms of the
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   7  *
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   9  * or http://www.opensolaris.org/os/licensing.
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  11  * and limitations under the License.
  12  *
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  15  * If applicable, add the following below this CDDL HEADER, with the
  16  * fields enclosed by brackets "[]" replaced with your own identifying
  17  * information: Portions Copyright [yyyy] [name of copyright owner]
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  20  */
  21 /*
  22  * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
  23  */
  24 
  25 /*
  26  * Kernel memory allocator, as described in the following two papers and a
  27  * statement about the consolidator:
  28  *
  29  * Jeff Bonwick,
  30  * The Slab Allocator: An Object-Caching Kernel Memory Allocator.
  31  * Proceedings of the Summer 1994 Usenix Conference.
  32  * Available as /shared/sac/PSARC/1994/028/materials/kmem.pdf.
  33  *
  34  * Jeff Bonwick and Jonathan Adams,
  35  * Magazines and vmem: Extending the Slab Allocator to Many CPUs and
  36  * Arbitrary Resources.
  37  * Proceedings of the 2001 Usenix Conference.
  38  * Available as /shared/sac/PSARC/2000/550/materials/vmem.pdf.
  39  *
  40  * kmem Slab Consolidator Big Theory Statement:
  41  *
  42  * 1. Motivation
  43  *
  44  * As stated in Bonwick94, slabs provide the following advantages over other
  45  * allocation structures in terms of memory fragmentation:
  46  *
  47  *  - Internal fragmentation (per-buffer wasted space) is minimal.
  48  *  - Severe external fragmentation (unused buffers on the free list) is
  49  *    unlikely.
  50  *
  51  * Segregating objects by size eliminates one source of external fragmentation,
  52  * and according to Bonwick:
  53  *
  54  *   The other reason that slabs reduce external fragmentation is that all
  55  *   objects in a slab are of the same type, so they have the same lifetime
  56  *   distribution. The resulting segregation of short-lived and long-lived
  57  *   objects at slab granularity reduces the likelihood of an entire page being
  58  *   held hostage due to a single long-lived allocation [Barrett93, Hanson90].
  59  *
  60  * While unlikely, severe external fragmentation remains possible. Clients that
  61  * allocate both short- and long-lived objects from the same cache cannot
  62  * anticipate the distribution of long-lived objects within the allocator's slab
  63  * implementation. Even a small percentage of long-lived objects distributed
  64  * randomly across many slabs can lead to a worst case scenario where the client
  65  * frees the majority of its objects and the system gets back almost none of the
  66  * slabs. Despite the client doing what it reasonably can to help the system
  67  * reclaim memory, the allocator cannot shake free enough slabs because of
  68  * lonely allocations stubbornly hanging on. Although the allocator is in a
  69  * position to diagnose the fragmentation, there is nothing that the allocator
  70  * by itself can do about it. It only takes a single allocated object to prevent
  71  * an entire slab from being reclaimed, and any object handed out by
  72  * kmem_cache_alloc() is by definition in the client's control. Conversely,
  73  * although the client is in a position to move a long-lived object, it has no
  74  * way of knowing if the object is causing fragmentation, and if so, where to
  75  * move it. A solution necessarily requires further cooperation between the
  76  * allocator and the client.
  77  *
  78  * 2. Move Callback
  79  *
  80  * The kmem slab consolidator therefore adds a move callback to the
  81  * allocator/client interface, improving worst-case external fragmentation in
  82  * kmem caches that supply a function to move objects from one memory location
  83  * to another. In a situation of low memory kmem attempts to consolidate all of
  84  * a cache's slabs at once; otherwise it works slowly to bring external
  85  * fragmentation within the 1/8 limit guaranteed for internal fragmentation,
  86  * thereby helping to avoid a low memory situation in the future.
  87  *
  88  * The callback has the following signature:
  89  *
  90  *   kmem_cbrc_t move(void *old, void *new, size_t size, void *user_arg)
  91  *
  92  * It supplies the kmem client with two addresses: the allocated object that
  93  * kmem wants to move and a buffer selected by kmem for the client to use as the
  94  * copy destination. The callback is kmem's way of saying "Please get off of
  95  * this buffer and use this one instead." kmem knows where it wants to move the
  96  * object in order to best reduce fragmentation. All the client needs to know
  97  * about the second argument (void *new) is that it is an allocated, constructed
  98  * object ready to take the contents of the old object. When the move function
  99  * is called, the system is likely to be low on memory, and the new object
 100  * spares the client from having to worry about allocating memory for the
 101  * requested move. The third argument supplies the size of the object, in case a
 102  * single move function handles multiple caches whose objects differ only in
 103  * size (such as zio_buf_512, zio_buf_1024, etc). Finally, the same optional
 104  * user argument passed to the constructor, destructor, and reclaim functions is
 105  * also passed to the move callback.
 106  *
 107  * 2.1 Setting the Move Callback
 108  *
 109  * The client sets the move callback after creating the cache and before
 110  * allocating from it:
 111  *
 112  *      object_cache = kmem_cache_create(...);
 113  *      kmem_cache_set_move(object_cache, object_move);
 114  *
 115  * 2.2 Move Callback Return Values
 116  *
 117  * Only the client knows about its own data and when is a good time to move it.
 118  * The client is cooperating with kmem to return unused memory to the system,
 119  * and kmem respectfully accepts this help at the client's convenience. When
 120  * asked to move an object, the client can respond with any of the following:
 121  *
 122  *   typedef enum kmem_cbrc {
 123  *           KMEM_CBRC_YES,
 124  *           KMEM_CBRC_NO,
 125  *           KMEM_CBRC_LATER,
 126  *           KMEM_CBRC_DONT_NEED,
 127  *           KMEM_CBRC_DONT_KNOW
 128  *   } kmem_cbrc_t;
 129  *
 130  * The client must not explicitly kmem_cache_free() either of the objects passed
 131  * to the callback, since kmem wants to free them directly to the slab layer
 132  * (bypassing the per-CPU magazine layer). The response tells kmem which of the
 133  * objects to free:
 134  *
 135  *       YES: (Did it) The client moved the object, so kmem frees the old one.
 136  *        NO: (Never) The client refused, so kmem frees the new object (the
 137  *            unused copy destination). kmem also marks the slab of the old
 138  *            object so as not to bother the client with further callbacks for
 139  *            that object as long as the slab remains on the partial slab list.
 140  *            (The system won't be getting the slab back as long as the
 141  *            immovable object holds it hostage, so there's no point in moving
 142  *            any of its objects.)
 143  *     LATER: The client is using the object and cannot move it now, so kmem
 144  *            frees the new object (the unused copy destination). kmem still
 145  *            attempts to move other objects off the slab, since it expects to
 146  *            succeed in clearing the slab in a later callback. The client
 147  *            should use LATER instead of NO if the object is likely to become
 148  *            movable very soon.
 149  * DONT_NEED: The client no longer needs the object, so kmem frees the old along
 150  *            with the new object (the unused copy destination). This response
 151  *            is the client's opportunity to be a model citizen and give back as
 152  *            much as it can.
 153  * DONT_KNOW: The client does not know about the object because
 154  *            a) the client has just allocated the object and not yet put it
 155  *               wherever it expects to find known objects
 156  *            b) the client has removed the object from wherever it expects to
 157  *               find known objects and is about to free it, or
 158  *            c) the client has freed the object.
 159  *            In all these cases (a, b, and c) kmem frees the new object (the
 160  *            unused copy destination) and searches for the old object in the
 161  *            magazine layer. If found, the object is removed from the magazine
 162  *            layer and freed to the slab layer so it will no longer hold the
 163  *            slab hostage.
 164  *
 165  * 2.3 Object States
 166  *
 167  * Neither kmem nor the client can be assumed to know the object's whereabouts
 168  * at the time of the callback. An object belonging to a kmem cache may be in
 169  * any of the following states:
 170  *
 171  * 1. Uninitialized on the slab
 172  * 2. Allocated from the slab but not constructed (still uninitialized)
 173  * 3. Allocated from the slab, constructed, but not yet ready for business
 174  *    (not in a valid state for the move callback)
 175  * 4. In use (valid and known to the client)
 176  * 5. About to be freed (no longer in a valid state for the move callback)
 177  * 6. Freed to a magazine (still constructed)
 178  * 7. Allocated from a magazine, not yet ready for business (not in a valid
 179  *    state for the move callback), and about to return to state #4
 180  * 8. Deconstructed on a magazine that is about to be freed
 181  * 9. Freed to the slab
 182  *
 183  * Since the move callback may be called at any time while the object is in any
 184  * of the above states (except state #1), the client needs a safe way to
 185  * determine whether or not it knows about the object. Specifically, the client
 186  * needs to know whether or not the object is in state #4, the only state in
 187  * which a move is valid. If the object is in any other state, the client should
 188  * immediately return KMEM_CBRC_DONT_KNOW, since it is unsafe to access any of
 189  * the object's fields.
 190  *
 191  * Note that although an object may be in state #4 when kmem initiates the move
 192  * request, the object may no longer be in that state by the time kmem actually
 193  * calls the move function. Not only does the client free objects
 194  * asynchronously, kmem itself puts move requests on a queue where thay are
 195  * pending until kmem processes them from another context. Also, objects freed
 196  * to a magazine appear allocated from the point of view of the slab layer, so
 197  * kmem may even initiate requests for objects in a state other than state #4.
 198  *
 199  * 2.3.1 Magazine Layer
 200  *
 201  * An important insight revealed by the states listed above is that the magazine
 202  * layer is populated only by kmem_cache_free(). Magazines of constructed
 203  * objects are never populated directly from the slab layer (which contains raw,
 204  * unconstructed objects). Whenever an allocation request cannot be satisfied
 205  * from the magazine layer, the magazines are bypassed and the request is
 206  * satisfied from the slab layer (creating a new slab if necessary). kmem calls
 207  * the object constructor only when allocating from the slab layer, and only in
 208  * response to kmem_cache_alloc() or to prepare the destination buffer passed in
 209  * the move callback. kmem does not preconstruct objects in anticipation of
 210  * kmem_cache_alloc().
 211  *
 212  * 2.3.2 Object Constructor and Destructor
 213  *
 214  * If the client supplies a destructor, it must be valid to call the destructor
 215  * on a newly created object (immediately after the constructor).
 216  *
 217  * 2.4 Recognizing Known Objects
 218  *
 219  * There is a simple test to determine safely whether or not the client knows
 220  * about a given object in the move callback. It relies on the fact that kmem
 221  * guarantees that the object of the move callback has only been touched by the
 222  * client itself or else by kmem. kmem does this by ensuring that none of the
 223  * cache's slabs are freed to the virtual memory (VM) subsystem while a move
 224  * callback is pending. When the last object on a slab is freed, if there is a
 225  * pending move, kmem puts the slab on a per-cache dead list and defers freeing
 226  * slabs on that list until all pending callbacks are completed. That way,
 227  * clients can be certain that the object of a move callback is in one of the
 228  * states listed above, making it possible to distinguish known objects (in
 229  * state #4) using the two low order bits of any pointer member (with the
 230  * exception of 'char *' or 'short *' which may not be 4-byte aligned on some
 231  * platforms).
 232  *
 233  * The test works as long as the client always transitions objects from state #4
 234  * (known, in use) to state #5 (about to be freed, invalid) by setting the low
 235  * order bit of the client-designated pointer member. Since kmem only writes
 236  * invalid memory patterns, such as 0xbaddcafe to uninitialized memory and
 237  * 0xdeadbeef to freed memory, any scribbling on the object done by kmem is
 238  * guaranteed to set at least one of the two low order bits. Therefore, given an
 239  * object with a back pointer to a 'container_t *o_container', the client can
 240  * test
 241  *
 242  *      container_t *container = object->o_container;
 243  *      if ((uintptr_t)container & 0x3) {
 244  *              return (KMEM_CBRC_DONT_KNOW);
 245  *      }
 246  *
 247  * Typically, an object will have a pointer to some structure with a list or
 248  * hash where objects from the cache are kept while in use. Assuming that the
 249  * client has some way of knowing that the container structure is valid and will
 250  * not go away during the move, and assuming that the structure includes a lock
 251  * to protect whatever collection is used, then the client would continue as
 252  * follows:
 253  *
 254  *      // Ensure that the container structure does not go away.
 255  *      if (container_hold(container) == 0) {
 256  *              return (KMEM_CBRC_DONT_KNOW);
 257  *      }
 258  *      mutex_enter(&container->c_objects_lock);
 259  *      if (container != object->o_container) {
 260  *              mutex_exit(&container->c_objects_lock);
 261  *              container_rele(container);
 262  *              return (KMEM_CBRC_DONT_KNOW);
 263  *      }
 264  *
 265  * At this point the client knows that the object cannot be freed as long as
 266  * c_objects_lock is held. Note that after acquiring the lock, the client must
 267  * recheck the o_container pointer in case the object was removed just before
 268  * acquiring the lock.
 269  *
 270  * When the client is about to free an object, it must first remove that object
 271  * from the list, hash, or other structure where it is kept. At that time, to
 272  * mark the object so it can be distinguished from the remaining, known objects,
 273  * the client sets the designated low order bit:
 274  *
 275  *      mutex_enter(&container->c_objects_lock);
 276  *      object->o_container = (void *)((uintptr_t)object->o_container | 0x1);
 277  *      list_remove(&container->c_objects, object);
 278  *      mutex_exit(&container->c_objects_lock);
 279  *
 280  * In the common case, the object is freed to the magazine layer, where it may
 281  * be reused on a subsequent allocation without the overhead of calling the
 282  * constructor. While in the magazine it appears allocated from the point of
 283  * view of the slab layer, making it a candidate for the move callback. Most
 284  * objects unrecognized by the client in the move callback fall into this
 285  * category and are cheaply distinguished from known objects by the test
 286  * described earlier. Since recognition is cheap for the client, and searching
 287  * magazines is expensive for kmem, kmem defers searching until the client first
 288  * returns KMEM_CBRC_DONT_KNOW. As long as the needed effort is reasonable, kmem
 289  * elsewhere does what it can to avoid bothering the client unnecessarily.
 290  *
 291  * Invalidating the designated pointer member before freeing the object marks
 292  * the object to be avoided in the callback, and conversely, assigning a valid
 293  * value to the designated pointer member after allocating the object makes the
 294  * object fair game for the callback:
 295  *
 296  *      ... allocate object ...
 297  *      ... set any initial state not set by the constructor ...
 298  *
 299  *      mutex_enter(&container->c_objects_lock);
 300  *      list_insert_tail(&container->c_objects, object);
 301  *      membar_producer();
 302  *      object->o_container = container;
 303  *      mutex_exit(&container->c_objects_lock);
 304  *
 305  * Note that everything else must be valid before setting o_container makes the
 306  * object fair game for the move callback. The membar_producer() call ensures
 307  * that all the object's state is written to memory before setting the pointer
 308  * that transitions the object from state #3 or #7 (allocated, constructed, not
 309  * yet in use) to state #4 (in use, valid). That's important because the move
 310  * function has to check the validity of the pointer before it can safely
 311  * acquire the lock protecting the collection where it expects to find known
 312  * objects.
 313  *
 314  * This method of distinguishing known objects observes the usual symmetry:
 315  * invalidating the designated pointer is the first thing the client does before
 316  * freeing the object, and setting the designated pointer is the last thing the
 317  * client does after allocating the object. Of course, the client is not
 318  * required to use this method. Fundamentally, how the client recognizes known
 319  * objects is completely up to the client, but this method is recommended as an
 320  * efficient and safe way to take advantage of the guarantees made by kmem. If
 321  * the entire object is arbitrary data without any markable bits from a suitable
 322  * pointer member, then the client must find some other method, such as
 323  * searching a hash table of known objects.
 324  *
 325  * 2.5 Preventing Objects From Moving
 326  *
 327  * Besides a way to distinguish known objects, the other thing that the client
 328  * needs is a strategy to ensure that an object will not move while the client
 329  * is actively using it. The details of satisfying this requirement tend to be
 330  * highly cache-specific. It might seem that the same rules that let a client
 331  * remove an object safely should also decide when an object can be moved
 332  * safely. However, any object state that makes a removal attempt invalid is
 333  * likely to be long-lasting for objects that the client does not expect to
 334  * remove. kmem knows nothing about the object state and is equally likely (from
 335  * the client's point of view) to request a move for any object in the cache,
 336  * whether prepared for removal or not. Even a low percentage of objects stuck
 337  * in place by unremovability will defeat the consolidator if the stuck objects
 338  * are the same long-lived allocations likely to hold slabs hostage.
 339  * Fundamentally, the consolidator is not aimed at common cases. Severe external
 340  * fragmentation is a worst case scenario manifested as sparsely allocated
 341  * slabs, by definition a low percentage of the cache's objects. When deciding
 342  * what makes an object movable, keep in mind the goal of the consolidator: to
 343  * bring worst-case external fragmentation within the limits guaranteed for
 344  * internal fragmentation. Removability is a poor criterion if it is likely to
 345  * exclude more than an insignificant percentage of objects for long periods of
 346  * time.
 347  *
 348  * A tricky general solution exists, and it has the advantage of letting you
 349  * move any object at almost any moment, practically eliminating the likelihood
 350  * that an object can hold a slab hostage. However, if there is a cache-specific
 351  * way to ensure that an object is not actively in use in the vast majority of
 352  * cases, a simpler solution that leverages this cache-specific knowledge is
 353  * preferred.
 354  *
 355  * 2.5.1 Cache-Specific Solution
 356  *
 357  * As an example of a cache-specific solution, the ZFS znode cache takes
 358  * advantage of the fact that the vast majority of znodes are only being
 359  * referenced from the DNLC. (A typical case might be a few hundred in active
 360  * use and a hundred thousand in the DNLC.) In the move callback, after the ZFS
 361  * client has established that it recognizes the znode and can access its fields
 362  * safely (using the method described earlier), it then tests whether the znode
 363  * is referenced by anything other than the DNLC. If so, it assumes that the
 364  * znode may be in active use and is unsafe to move, so it drops its locks and
 365  * returns KMEM_CBRC_LATER. The advantage of this strategy is that everywhere
 366  * else znodes are used, no change is needed to protect against the possibility
 367  * of the znode moving. The disadvantage is that it remains possible for an
 368  * application to hold a znode slab hostage with an open file descriptor.
 369  * However, this case ought to be rare and the consolidator has a way to deal
 370  * with it: If the client responds KMEM_CBRC_LATER repeatedly for the same
 371  * object, kmem eventually stops believing it and treats the slab as if the
 372  * client had responded KMEM_CBRC_NO. Having marked the hostage slab, kmem can
 373  * then focus on getting it off of the partial slab list by allocating rather
 374  * than freeing all of its objects. (Either way of getting a slab off the
 375  * free list reduces fragmentation.)
 376  *
 377  * 2.5.2 General Solution
 378  *
 379  * The general solution, on the other hand, requires an explicit hold everywhere
 380  * the object is used to prevent it from moving. To keep the client locking
 381  * strategy as uncomplicated as possible, kmem guarantees the simplifying
 382  * assumption that move callbacks are sequential, even across multiple caches.
 383  * Internally, a global queue processed by a single thread supports all caches
 384  * implementing the callback function. No matter how many caches supply a move
 385  * function, the consolidator never moves more than one object at a time, so the
 386  * client does not have to worry about tricky lock ordering involving several
 387  * related objects from different kmem caches.
 388  *
 389  * The general solution implements the explicit hold as a read-write lock, which
 390  * allows multiple readers to access an object from the cache simultaneously
 391  * while a single writer is excluded from moving it. A single rwlock for the
 392  * entire cache would lock out all threads from using any of the cache's objects
 393  * even though only a single object is being moved, so to reduce contention,
 394  * the client can fan out the single rwlock into an array of rwlocks hashed by
 395  * the object address, making it probable that moving one object will not
 396  * prevent other threads from using a different object. The rwlock cannot be a
 397  * member of the object itself, because the possibility of the object moving
 398  * makes it unsafe to access any of the object's fields until the lock is
 399  * acquired.
 400  *
 401  * Assuming a small, fixed number of locks, it's possible that multiple objects
 402  * will hash to the same lock. A thread that needs to use multiple objects in
 403  * the same function may acquire the same lock multiple times. Since rwlocks are
 404  * reentrant for readers, and since there is never more than a single writer at
 405  * a time (assuming that the client acquires the lock as a writer only when
 406  * moving an object inside the callback), there would seem to be no problem.
 407  * However, a client locking multiple objects in the same function must handle
 408  * one case of potential deadlock: Assume that thread A needs to prevent both
 409  * object 1 and object 2 from moving, and thread B, the callback, meanwhile
 410  * tries to move object 3. It's possible, if objects 1, 2, and 3 all hash to the
 411  * same lock, that thread A will acquire the lock for object 1 as a reader
 412  * before thread B sets the lock's write-wanted bit, preventing thread A from
 413  * reacquiring the lock for object 2 as a reader. Unable to make forward
 414  * progress, thread A will never release the lock for object 1, resulting in
 415  * deadlock.
 416  *
 417  * There are two ways of avoiding the deadlock just described. The first is to
 418  * use rw_tryenter() rather than rw_enter() in the callback function when
 419  * attempting to acquire the lock as a writer. If tryenter discovers that the
 420  * same object (or another object hashed to the same lock) is already in use, it
 421  * aborts the callback and returns KMEM_CBRC_LATER. The second way is to use
 422  * rprwlock_t (declared in common/fs/zfs/sys/rprwlock.h) instead of rwlock_t,
 423  * since it allows a thread to acquire the lock as a reader in spite of a
 424  * waiting writer. This second approach insists on moving the object now, no
 425  * matter how many readers the move function must wait for in order to do so,
 426  * and could delay the completion of the callback indefinitely (blocking
 427  * callbacks to other clients). In practice, a less insistent callback using
 428  * rw_tryenter() returns KMEM_CBRC_LATER infrequently enough that there seems
 429  * little reason to use anything else.
 430  *
 431  * Avoiding deadlock is not the only problem that an implementation using an
 432  * explicit hold needs to solve. Locking the object in the first place (to
 433  * prevent it from moving) remains a problem, since the object could move
 434  * between the time you obtain a pointer to the object and the time you acquire
 435  * the rwlock hashed to that pointer value. Therefore the client needs to
 436  * recheck the value of the pointer after acquiring the lock, drop the lock if
 437  * the value has changed, and try again. This requires a level of indirection:
 438  * something that points to the object rather than the object itself, that the
 439  * client can access safely while attempting to acquire the lock. (The object
 440  * itself cannot be referenced safely because it can move at any time.)
 441  * The following lock-acquisition function takes whatever is safe to reference
 442  * (arg), follows its pointer to the object (using function f), and tries as
 443  * often as necessary to acquire the hashed lock and verify that the object
 444  * still has not moved:
 445  *
 446  *      object_t *
 447  *      object_hold(object_f f, void *arg)
 448  *      {
 449  *              object_t *op;
 450  *
 451  *              op = f(arg);
 452  *              if (op == NULL) {
 453  *                      return (NULL);
 454  *              }
 455  *
 456  *              rw_enter(OBJECT_RWLOCK(op), RW_READER);
 457  *              while (op != f(arg)) {
 458  *                      rw_exit(OBJECT_RWLOCK(op));
 459  *                      op = f(arg);
 460  *                      if (op == NULL) {
 461  *                              break;
 462  *                      }
 463  *                      rw_enter(OBJECT_RWLOCK(op), RW_READER);
 464  *              }
 465  *
 466  *              return (op);
 467  *      }
 468  *
 469  * The OBJECT_RWLOCK macro hashes the object address to obtain the rwlock. The
 470  * lock reacquisition loop, while necessary, almost never executes. The function
 471  * pointer f (used to obtain the object pointer from arg) has the following type
 472  * definition:
 473  *
 474  *      typedef object_t *(*object_f)(void *arg);
 475  *
 476  * An object_f implementation is likely to be as simple as accessing a structure
 477  * member:
 478  *
 479  *      object_t *
 480  *      s_object(void *arg)
 481  *      {
 482  *              something_t *sp = arg;
 483  *              return (sp->s_object);
 484  *      }
 485  *
 486  * The flexibility of a function pointer allows the path to the object to be
 487  * arbitrarily complex and also supports the notion that depending on where you
 488  * are using the object, you may need to get it from someplace different.
 489  *
 490  * The function that releases the explicit hold is simpler because it does not
 491  * have to worry about the object moving:
 492  *
 493  *      void
 494  *      object_rele(object_t *op)
 495  *      {
 496  *              rw_exit(OBJECT_RWLOCK(op));
 497  *      }
 498  *
 499  * The caller is spared these details so that obtaining and releasing an
 500  * explicit hold feels like a simple mutex_enter()/mutex_exit() pair. The caller
 501  * of object_hold() only needs to know that the returned object pointer is valid
 502  * if not NULL and that the object will not move until released.
 503  *
 504  * Although object_hold() prevents an object from moving, it does not prevent it
 505  * from being freed. The caller must take measures before calling object_hold()
 506  * (afterwards is too late) to ensure that the held object cannot be freed. The
 507  * caller must do so without accessing the unsafe object reference, so any lock
 508  * or reference count used to ensure the continued existence of the object must
 509  * live outside the object itself.
 510  *
 511  * Obtaining a new object is a special case where an explicit hold is impossible
 512  * for the caller. Any function that returns a newly allocated object (either as
 513  * a return value, or as an in-out paramter) must return it already held; after
 514  * the caller gets it is too late, since the object cannot be safely accessed
 515  * without the level of indirection described earlier. The following
 516  * object_alloc() example uses the same code shown earlier to transition a new
 517  * object into the state of being recognized (by the client) as a known object.
 518  * The function must acquire the hold (rw_enter) before that state transition
 519  * makes the object movable:
 520  *
 521  *      static object_t *
 522  *      object_alloc(container_t *container)
 523  *      {
 524  *              object_t *object = kmem_cache_alloc(object_cache, 0);
 525  *              ... set any initial state not set by the constructor ...
 526  *              rw_enter(OBJECT_RWLOCK(object), RW_READER);
 527  *              mutex_enter(&container->c_objects_lock);
 528  *              list_insert_tail(&container->c_objects, object);
 529  *              membar_producer();
 530  *              object->o_container = container;
 531  *              mutex_exit(&container->c_objects_lock);
 532  *              return (object);
 533  *      }
 534  *
 535  * Functions that implicitly acquire an object hold (any function that calls
 536  * object_alloc() to supply an object for the caller) need to be carefully noted
 537  * so that the matching object_rele() is not neglected. Otherwise, leaked holds
 538  * prevent all objects hashed to the affected rwlocks from ever being moved.
 539  *
 540  * The pointer to a held object can be hashed to the holding rwlock even after
 541  * the object has been freed. Although it is possible to release the hold
 542  * after freeing the object, you may decide to release the hold implicitly in
 543  * whatever function frees the object, so as to release the hold as soon as
 544  * possible, and for the sake of symmetry with the function that implicitly
 545  * acquires the hold when it allocates the object. Here, object_free() releases
 546  * the hold acquired by object_alloc(). Its implicit object_rele() forms a
 547  * matching pair with object_hold():
 548  *
 549  *      void
 550  *      object_free(object_t *object)
 551  *      {
 552  *              container_t *container;
 553  *
 554  *              ASSERT(object_held(object));
 555  *              container = object->o_container;
 556  *              mutex_enter(&container->c_objects_lock);
 557  *              object->o_container =
 558  *                  (void *)((uintptr_t)object->o_container | 0x1);
 559  *              list_remove(&container->c_objects, object);
 560  *              mutex_exit(&container->c_objects_lock);
 561  *              object_rele(object);
 562  *              kmem_cache_free(object_cache, object);
 563  *      }
 564  *
 565  * Note that object_free() cannot safely accept an object pointer as an argument
 566  * unless the object is already held. Any function that calls object_free()
 567  * needs to be carefully noted since it similarly forms a matching pair with
 568  * object_hold().
 569  *
 570  * To complete the picture, the following callback function implements the
 571  * general solution by moving objects only if they are currently unheld:
 572  *
 573  *      static kmem_cbrc_t
 574  *      object_move(void *buf, void *newbuf, size_t size, void *arg)
 575  *      {
 576  *              object_t *op = buf, *np = newbuf;
 577  *              container_t *container;
 578  *
 579  *              container = op->o_container;
 580  *              if ((uintptr_t)container & 0x3) {
 581  *                      return (KMEM_CBRC_DONT_KNOW);
 582  *              }
 583  *
 584  *              // Ensure that the container structure does not go away.
 585  *              if (container_hold(container) == 0) {
 586  *                      return (KMEM_CBRC_DONT_KNOW);
 587  *              }
 588  *
 589  *              mutex_enter(&container->c_objects_lock);
 590  *              if (container != op->o_container) {
 591  *                      mutex_exit(&container->c_objects_lock);
 592  *                      container_rele(container);
 593  *                      return (KMEM_CBRC_DONT_KNOW);
 594  *              }
 595  *
 596  *              if (rw_tryenter(OBJECT_RWLOCK(op), RW_WRITER) == 0) {
 597  *                      mutex_exit(&container->c_objects_lock);
 598  *                      container_rele(container);
 599  *                      return (KMEM_CBRC_LATER);
 600  *              }
 601  *
 602  *              object_move_impl(op, np); // critical section
 603  *              rw_exit(OBJECT_RWLOCK(op));
 604  *
 605  *              op->o_container = (void *)((uintptr_t)op->o_container | 0x1);
 606  *              list_link_replace(&op->o_link_node, &np->o_link_node);
 607  *              mutex_exit(&container->c_objects_lock);
 608  *              container_rele(container);
 609  *              return (KMEM_CBRC_YES);
 610  *      }
 611  *
 612  * Note that object_move() must invalidate the designated o_container pointer of
 613  * the old object in the same way that object_free() does, since kmem will free
 614  * the object in response to the KMEM_CBRC_YES return value.
 615  *
 616  * The lock order in object_move() differs from object_alloc(), which locks
 617  * OBJECT_RWLOCK first and &container->c_objects_lock second, but as long as the
 618  * callback uses rw_tryenter() (preventing the deadlock described earlier), it's
 619  * not a problem. Holding the lock on the object list in the example above
 620  * through the entire callback not only prevents the object from going away, it
 621  * also allows you to lock the list elsewhere and know that none of its elements
 622  * will move during iteration.
 623  *
 624  * Adding an explicit hold everywhere an object from the cache is used is tricky
 625  * and involves much more change to client code than a cache-specific solution
 626  * that leverages existing state to decide whether or not an object is
 627  * movable. However, this approach has the advantage that no object remains
 628  * immovable for any significant length of time, making it extremely unlikely
 629  * that long-lived allocations can continue holding slabs hostage; and it works
 630  * for any cache.
 631  *
 632  * 3. Consolidator Implementation
 633  *
 634  * Once the client supplies a move function that a) recognizes known objects and
 635  * b) avoids moving objects that are actively in use, the remaining work is up
 636  * to the consolidator to decide which objects to move and when to issue
 637  * callbacks.
 638  *
 639  * The consolidator relies on the fact that a cache's slabs are ordered by
 640  * usage. Each slab has a fixed number of objects. Depending on the slab's
 641  * "color" (the offset of the first object from the beginning of the slab;
 642  * offsets are staggered to mitigate false sharing of cache lines) it is either
 643  * the maximum number of objects per slab determined at cache creation time or
 644  * else the number closest to the maximum that fits within the space remaining
 645  * after the initial offset. A completely allocated slab may contribute some
 646  * internal fragmentation (per-slab overhead) but no external fragmentation, so
 647  * it is of no interest to the consolidator. At the other extreme, slabs whose
 648  * objects have all been freed to the slab are released to the virtual memory
 649  * (VM) subsystem (objects freed to magazines are still allocated as far as the
 650  * slab is concerned). External fragmentation exists when there are slabs
 651  * somewhere between these extremes. A partial slab has at least one but not all
 652  * of its objects allocated. The more partial slabs, and the fewer allocated
 653  * objects on each of them, the higher the fragmentation. Hence the
 654  * consolidator's overall strategy is to reduce the number of partial slabs by
 655  * moving allocated objects from the least allocated slabs to the most allocated
 656  * slabs.
 657  *
 658  * Partial slabs are kept in an AVL tree ordered by usage. Completely allocated
 659  * slabs are kept separately in an unordered list. Since the majority of slabs
 660  * tend to be completely allocated (a typical unfragmented cache may have
 661  * thousands of complete slabs and only a single partial slab), separating
 662  * complete slabs improves the efficiency of partial slab ordering, since the
 663  * complete slabs do not affect the depth or balance of the AVL tree. This
 664  * ordered sequence of partial slabs acts as a "free list" supplying objects for
 665  * allocation requests.
 666  *
 667  * Objects are always allocated from the first partial slab in the free list,
 668  * where the allocation is most likely to eliminate a partial slab (by
 669  * completely allocating it). Conversely, when a single object from a completely
 670  * allocated slab is freed to the slab, that slab is added to the front of the
 671  * free list. Since most free list activity involves highly allocated slabs
 672  * coming and going at the front of the list, slabs tend naturally toward the
 673  * ideal order: highly allocated at the front, sparsely allocated at the back.
 674  * Slabs with few allocated objects are likely to become completely free if they
 675  * keep a safe distance away from the front of the free list. Slab misorders
 676  * interfere with the natural tendency of slabs to become completely free or
 677  * completely allocated. For example, a slab with a single allocated object
 678  * needs only a single free to escape the cache; its natural desire is
 679  * frustrated when it finds itself at the front of the list where a second
 680  * allocation happens just before the free could have released it. Another slab
 681  * with all but one object allocated might have supplied the buffer instead, so
 682  * that both (as opposed to neither) of the slabs would have been taken off the
 683  * free list.
 684  *
 685  * Although slabs tend naturally toward the ideal order, misorders allowed by a
 686  * simple list implementation defeat the consolidator's strategy of merging
 687  * least- and most-allocated slabs. Without an AVL tree to guarantee order, kmem
 688  * needs another way to fix misorders to optimize its callback strategy. One
 689  * approach is to periodically scan a limited number of slabs, advancing a
 690  * marker to hold the current scan position, and to move extreme misorders to
 691  * the front or back of the free list and to the front or back of the current
 692  * scan range. By making consecutive scan ranges overlap by one slab, the least
 693  * allocated slab in the current range can be carried along from the end of one
 694  * scan to the start of the next.
 695  *
 696  * Maintaining partial slabs in an AVL tree relieves kmem of this additional
 697  * task, however. Since most of the cache's activity is in the magazine layer,
 698  * and allocations from the slab layer represent only a startup cost, the
 699  * overhead of maintaining a balanced tree is not a significant concern compared
 700  * to the opportunity of reducing complexity by eliminating the partial slab
 701  * scanner just described. The overhead of an AVL tree is minimized by
 702  * maintaining only partial slabs in the tree and keeping completely allocated
 703  * slabs separately in a list. To avoid increasing the size of the slab
 704  * structure the AVL linkage pointers are reused for the slab's list linkage,
 705  * since the slab will always be either partial or complete, never stored both
 706  * ways at the same time. To further minimize the overhead of the AVL tree the
 707  * compare function that orders partial slabs by usage divides the range of
 708  * allocated object counts into bins such that counts within the same bin are
 709  * considered equal. Binning partial slabs makes it less likely that allocating
 710  * or freeing a single object will change the slab's order, requiring a tree
 711  * reinsertion (an avl_remove() followed by an avl_add(), both potentially
 712  * requiring some rebalancing of the tree). Allocation counts closest to
 713  * completely free and completely allocated are left unbinned (finely sorted) to
 714  * better support the consolidator's strategy of merging slabs at either
 715  * extreme.
 716  *
 717  * 3.1 Assessing Fragmentation and Selecting Candidate Slabs
 718  *
 719  * The consolidator piggybacks on the kmem maintenance thread and is called on
 720  * the same interval as kmem_cache_update(), once per cache every fifteen
 721  * seconds. kmem maintains a running count of unallocated objects in the slab
 722  * layer (cache_bufslab). The consolidator checks whether that number exceeds
 723  * 12.5% (1/8) of the total objects in the cache (cache_buftotal), and whether
 724  * there is a significant number of slabs in the cache (arbitrarily a minimum
 725  * 101 total slabs). Unused objects that have fallen out of the magazine layer's
 726  * working set are included in the assessment, and magazines in the depot are
 727  * reaped if those objects would lift cache_bufslab above the fragmentation
 728  * threshold. Once the consolidator decides that a cache is fragmented, it looks
 729  * for a candidate slab to reclaim, starting at the end of the partial slab free
 730  * list and scanning backwards. At first the consolidator is choosy: only a slab
 731  * with fewer than 12.5% (1/8) of its objects allocated qualifies (or else a
 732  * single allocated object, regardless of percentage). If there is difficulty
 733  * finding a candidate slab, kmem raises the allocation threshold incrementally,
 734  * up to a maximum 87.5% (7/8), so that eventually the consolidator will reduce
 735  * external fragmentation (unused objects on the free list) below 12.5% (1/8),
 736  * even in the worst case of every slab in the cache being almost 7/8 allocated.
 737  * The threshold can also be lowered incrementally when candidate slabs are easy
 738  * to find, and the threshold is reset to the minimum 1/8 as soon as the cache
 739  * is no longer fragmented.
 740  *
 741  * 3.2 Generating Callbacks
 742  *
 743  * Once an eligible slab is chosen, a callback is generated for every allocated
 744  * object on the slab, in the hope that the client will move everything off the
 745  * slab and make it reclaimable. Objects selected as move destinations are
 746  * chosen from slabs at the front of the free list. Assuming slabs in the ideal
 747  * order (most allocated at the front, least allocated at the back) and a
 748  * cooperative client, the consolidator will succeed in removing slabs from both
 749  * ends of the free list, completely allocating on the one hand and completely
 750  * freeing on the other. Objects selected as move destinations are allocated in
 751  * the kmem maintenance thread where move requests are enqueued. A separate
 752  * callback thread removes pending callbacks from the queue and calls the
 753  * client. The separate thread ensures that client code (the move function) does
 754  * not interfere with internal kmem maintenance tasks. A map of pending
 755  * callbacks keyed by object address (the object to be moved) is checked to
 756  * ensure that duplicate callbacks are not generated for the same object.
 757  * Allocating the move destination (the object to move to) prevents subsequent
 758  * callbacks from selecting the same destination as an earlier pending callback.
 759  *
 760  * Move requests can also be generated by kmem_cache_reap() when the system is
 761  * desperate for memory and by kmem_cache_move_notify(), called by the client to
 762  * notify kmem that a move refused earlier with KMEM_CBRC_LATER is now possible.
 763  * The map of pending callbacks is protected by the same lock that protects the
 764  * slab layer.
 765  *
 766  * When the system is desperate for memory, kmem does not bother to determine
 767  * whether or not the cache exceeds the fragmentation threshold, but tries to
 768  * consolidate as many slabs as possible. Normally, the consolidator chews
 769  * slowly, one sparsely allocated slab at a time during each maintenance
 770  * interval that the cache is fragmented. When desperate, the consolidator
 771  * starts at the last partial slab and enqueues callbacks for every allocated
 772  * object on every partial slab, working backwards until it reaches the first
 773  * partial slab. The first partial slab, meanwhile, advances in pace with the
 774  * consolidator as allocations to supply move destinations for the enqueued
 775  * callbacks use up the highly allocated slabs at the front of the free list.
 776  * Ideally, the overgrown free list collapses like an accordion, starting at
 777  * both ends and ending at the center with a single partial slab.
 778  *
 779  * 3.3 Client Responses
 780  *
 781  * When the client returns KMEM_CBRC_NO in response to the move callback, kmem
 782  * marks the slab that supplied the stuck object non-reclaimable and moves it to
 783  * front of the free list. The slab remains marked as long as it remains on the
 784  * free list, and it appears more allocated to the partial slab compare function
 785  * than any unmarked slab, no matter how many of its objects are allocated.
 786  * Since even one immovable object ties up the entire slab, the goal is to
 787  * completely allocate any slab that cannot be completely freed. kmem does not
 788  * bother generating callbacks to move objects from a marked slab unless the
 789  * system is desperate.
 790  *
 791  * When the client responds KMEM_CBRC_LATER, kmem increments a count for the
 792  * slab. If the client responds LATER too many times, kmem disbelieves and
 793  * treats the response as a NO. The count is cleared when the slab is taken off
 794  * the partial slab list or when the client moves one of the slab's objects.
 795  *
 796  * 4. Observability
 797  *
 798  * A kmem cache's external fragmentation is best observed with 'mdb -k' using
 799  * the ::kmem_slabs dcmd. For a complete description of the command, enter
 800  * '::help kmem_slabs' at the mdb prompt.
 801  */
 802 
 803 #include <sys/kmem_impl.h>
 804 #include <sys/vmem_impl.h>
 805 #include <sys/param.h>
 806 #include <sys/sysmacros.h>
 807 #include <sys/vm.h>
 808 #include <sys/proc.h>
 809 #include <sys/tuneable.h>
 810 #include <sys/systm.h>
 811 #include <sys/cmn_err.h>
 812 #include <sys/debug.h>
 813 #include <sys/sdt.h>
 814 #include <sys/mutex.h>
 815 #include <sys/bitmap.h>
 816 #include <sys/atomic.h>
 817 #include <sys/kobj.h>
 818 #include <sys/disp.h>
 819 #include <vm/seg_kmem.h>
 820 #include <sys/log.h>
 821 #include <sys/callb.h>
 822 #include <sys/taskq.h>
 823 #include <sys/modctl.h>
 824 #include <sys/reboot.h>
 825 #include <sys/id32.h>
 826 #include <sys/zone.h>
 827 #include <sys/netstack.h>
 828 #ifdef  DEBUG
 829 #include <sys/random.h>
 830 #endif
 831 
 832 extern void streams_msg_init(void);
 833 extern int segkp_fromheap;
 834 extern void segkp_cache_free(void);
 835 extern int callout_init_done;
 836 
 837 struct kmem_cache_kstat {
 838         kstat_named_t   kmc_buf_size;
 839         kstat_named_t   kmc_align;
 840         kstat_named_t   kmc_chunk_size;
 841         kstat_named_t   kmc_slab_size;
 842         kstat_named_t   kmc_alloc;
 843         kstat_named_t   kmc_alloc_fail;
 844         kstat_named_t   kmc_free;
 845         kstat_named_t   kmc_depot_alloc;
 846         kstat_named_t   kmc_depot_free;
 847         kstat_named_t   kmc_depot_contention;
 848         kstat_named_t   kmc_slab_alloc;
 849         kstat_named_t   kmc_slab_free;
 850         kstat_named_t   kmc_buf_constructed;
 851         kstat_named_t   kmc_buf_avail;
 852         kstat_named_t   kmc_buf_inuse;
 853         kstat_named_t   kmc_buf_total;
 854         kstat_named_t   kmc_buf_max;
 855         kstat_named_t   kmc_slab_create;
 856         kstat_named_t   kmc_slab_destroy;
 857         kstat_named_t   kmc_vmem_source;
 858         kstat_named_t   kmc_hash_size;
 859         kstat_named_t   kmc_hash_lookup_depth;
 860         kstat_named_t   kmc_hash_rescale;
 861         kstat_named_t   kmc_full_magazines;
 862         kstat_named_t   kmc_empty_magazines;
 863         kstat_named_t   kmc_magazine_size;
 864         kstat_named_t   kmc_reap; /* number of kmem_cache_reap() calls */
 865         kstat_named_t   kmc_defrag; /* attempts to defrag all partial slabs */
 866         kstat_named_t   kmc_scan; /* attempts to defrag one partial slab */
 867         kstat_named_t   kmc_move_callbacks; /* sum of yes, no, later, dn, dk */
 868         kstat_named_t   kmc_move_yes;
 869         kstat_named_t   kmc_move_no;
 870         kstat_named_t   kmc_move_later;
 871         kstat_named_t   kmc_move_dont_need;
 872         kstat_named_t   kmc_move_dont_know; /* obj unrecognized by client ... */
 873         kstat_named_t   kmc_move_hunt_found; /* ... but found in mag layer */
 874         kstat_named_t   kmc_move_slabs_freed; /* slabs freed by consolidator */
 875         kstat_named_t   kmc_move_reclaimable; /* buffers, if consolidator ran */
 876 } kmem_cache_kstat = {
 877         { "buf_size",           KSTAT_DATA_UINT64 },
 878         { "align",              KSTAT_DATA_UINT64 },
 879         { "chunk_size",         KSTAT_DATA_UINT64 },
 880         { "slab_size",          KSTAT_DATA_UINT64 },
 881         { "alloc",              KSTAT_DATA_UINT64 },
 882         { "alloc_fail",         KSTAT_DATA_UINT64 },
 883         { "free",               KSTAT_DATA_UINT64 },
 884         { "depot_alloc",        KSTAT_DATA_UINT64 },
 885         { "depot_free",         KSTAT_DATA_UINT64 },
 886         { "depot_contention",   KSTAT_DATA_UINT64 },
 887         { "slab_alloc",         KSTAT_DATA_UINT64 },
 888         { "slab_free",          KSTAT_DATA_UINT64 },
 889         { "buf_constructed",    KSTAT_DATA_UINT64 },
 890         { "buf_avail",          KSTAT_DATA_UINT64 },
 891         { "buf_inuse",          KSTAT_DATA_UINT64 },
 892         { "buf_total",          KSTAT_DATA_UINT64 },
 893         { "buf_max",            KSTAT_DATA_UINT64 },
 894         { "slab_create",        KSTAT_DATA_UINT64 },
 895         { "slab_destroy",       KSTAT_DATA_UINT64 },
 896         { "vmem_source",        KSTAT_DATA_UINT64 },
 897         { "hash_size",          KSTAT_DATA_UINT64 },
 898         { "hash_lookup_depth",  KSTAT_DATA_UINT64 },
 899         { "hash_rescale",       KSTAT_DATA_UINT64 },
 900         { "full_magazines",     KSTAT_DATA_UINT64 },
 901         { "empty_magazines",    KSTAT_DATA_UINT64 },
 902         { "magazine_size",      KSTAT_DATA_UINT64 },
 903         { "reap",               KSTAT_DATA_UINT64 },
 904         { "defrag",             KSTAT_DATA_UINT64 },
 905         { "scan",               KSTAT_DATA_UINT64 },
 906         { "move_callbacks",     KSTAT_DATA_UINT64 },
 907         { "move_yes",           KSTAT_DATA_UINT64 },
 908         { "move_no",            KSTAT_DATA_UINT64 },
 909         { "move_later",         KSTAT_DATA_UINT64 },
 910         { "move_dont_need",     KSTAT_DATA_UINT64 },
 911         { "move_dont_know",     KSTAT_DATA_UINT64 },
 912         { "move_hunt_found",    KSTAT_DATA_UINT64 },
 913         { "move_slabs_freed",   KSTAT_DATA_UINT64 },
 914         { "move_reclaimable",   KSTAT_DATA_UINT64 },
 915 };
 916 
 917 static kmutex_t kmem_cache_kstat_lock;
 918 
 919 /*
 920  * The default set of caches to back kmem_alloc().
 921  * These sizes should be reevaluated periodically.
 922  *
 923  * We want allocations that are multiples of the coherency granularity
 924  * (64 bytes) to be satisfied from a cache which is a multiple of 64
 925  * bytes, so that it will be 64-byte aligned.  For all multiples of 64,
 926  * the next kmem_cache_size greater than or equal to it must be a
 927  * multiple of 64.
 928  *
 929  * We split the table into two sections:  size <= 4k and size > 4k.  This
 930  * saves a lot of space and cache footprint in our cache tables.
 931  */
 932 static const int kmem_alloc_sizes[] = {
 933         1 * 8,
 934         2 * 8,
 935         3 * 8,
 936         4 * 8,          5 * 8,          6 * 8,          7 * 8,
 937         4 * 16,         5 * 16,         6 * 16,         7 * 16,
 938         4 * 32,         5 * 32,         6 * 32,         7 * 32,
 939         4 * 64,         5 * 64,         6 * 64,         7 * 64,
 940         4 * 128,        5 * 128,        6 * 128,        7 * 128,
 941         P2ALIGN(8192 / 7, 64),
 942         P2ALIGN(8192 / 6, 64),
 943         P2ALIGN(8192 / 5, 64),
 944         P2ALIGN(8192 / 4, 64),
 945         P2ALIGN(8192 / 3, 64),
 946         P2ALIGN(8192 / 2, 64),
 947 };
 948 
 949 static const int kmem_big_alloc_sizes[] = {
 950         2 * 4096,       3 * 4096,
 951         2 * 8192,       3 * 8192,
 952         4 * 8192,       5 * 8192,       6 * 8192,       7 * 8192,
 953         8 * 8192,       9 * 8192,       10 * 8192,      11 * 8192,
 954         12 * 8192,      13 * 8192,      14 * 8192,      15 * 8192,
 955         16 * 8192
 956 };
 957 
 958 #define KMEM_MAXBUF             4096
 959 #define KMEM_BIG_MAXBUF_32BIT   32768
 960 #define KMEM_BIG_MAXBUF         131072
 961 
 962 #define KMEM_BIG_MULTIPLE       4096    /* big_alloc_sizes must be a multiple */
 963 #define KMEM_BIG_SHIFT          12      /* lg(KMEM_BIG_MULTIPLE) */
 964 
 965 static kmem_cache_t *kmem_alloc_table[KMEM_MAXBUF >> KMEM_ALIGN_SHIFT];
 966 static kmem_cache_t *kmem_big_alloc_table[KMEM_BIG_MAXBUF >> KMEM_BIG_SHIFT];
 967 
 968 #define KMEM_ALLOC_TABLE_MAX    (KMEM_MAXBUF >> KMEM_ALIGN_SHIFT)
 969 static size_t kmem_big_alloc_table_max = 0;     /* # of filled elements */
 970 
 971 static kmem_magtype_t kmem_magtype[] = {
 972         { 1,    8,      3200,   65536   },
 973         { 3,    16,     256,    32768   },
 974         { 7,    32,     64,     16384   },
 975         { 15,   64,     0,      8192    },
 976         { 31,   64,     0,      4096    },
 977         { 47,   64,     0,      2048    },
 978         { 63,   64,     0,      1024    },
 979         { 95,   64,     0,      512     },
 980         { 143,  64,     0,      0       },
 981 };
 982 
 983 static uint32_t kmem_reaping;
 984 static uint32_t kmem_reaping_idspace;
 985 
 986 /*
 987  * kmem tunables
 988  */
 989 clock_t kmem_reap_interval;     /* cache reaping rate [15 * HZ ticks] */
 990 int kmem_depot_contention = 3;  /* max failed tryenters per real interval */
 991 pgcnt_t kmem_reapahead = 0;     /* start reaping N pages before pageout */
 992 int kmem_panic = 1;             /* whether to panic on error */
 993 int kmem_logging = 1;           /* kmem_log_enter() override */
 994 uint32_t kmem_mtbf = 0;         /* mean time between failures [default: off] */
 995 size_t kmem_transaction_log_size; /* transaction log size [2% of memory] */
 996 size_t kmem_content_log_size;   /* content log size [2% of memory] */
 997 size_t kmem_failure_log_size;   /* failure log [4 pages per CPU] */
 998 size_t kmem_slab_log_size;      /* slab create log [4 pages per CPU] */
 999 size_t kmem_content_maxsave = 256; /* KMF_CONTENTS max bytes to log */
1000 size_t kmem_lite_minsize = 0;   /* minimum buffer size for KMF_LITE */
1001 size_t kmem_lite_maxalign = 1024; /* maximum buffer alignment for KMF_LITE */
1002 int kmem_lite_pcs = 4;          /* number of PCs to store in KMF_LITE mode */
1003 size_t kmem_maxverify;          /* maximum bytes to inspect in debug routines */
1004 size_t kmem_minfirewall;        /* hardware-enforced redzone threshold */
1005 
1006 #ifdef _LP64
1007 size_t  kmem_max_cached = KMEM_BIG_MAXBUF;      /* maximum kmem_alloc cache */
1008 #else
1009 size_t  kmem_max_cached = KMEM_BIG_MAXBUF_32BIT; /* maximum kmem_alloc cache */
1010 #endif
1011 
1012 #ifdef DEBUG
1013 int kmem_flags = KMF_AUDIT | KMF_DEADBEEF | KMF_REDZONE | KMF_CONTENTS;
1014 #else
1015 int kmem_flags = 0;
1016 #endif
1017 int kmem_ready;
1018 
1019 static kmem_cache_t     *kmem_slab_cache;
1020 static kmem_cache_t     *kmem_bufctl_cache;
1021 static kmem_cache_t     *kmem_bufctl_audit_cache;
1022 
1023 static kmutex_t         kmem_cache_lock;        /* inter-cache linkage only */
1024 static list_t           kmem_caches;
1025 
1026 static taskq_t          *kmem_taskq;
1027 static kmutex_t         kmem_flags_lock;
1028 static vmem_t           *kmem_metadata_arena;
1029 static vmem_t           *kmem_msb_arena;        /* arena for metadata caches */
1030 static vmem_t           *kmem_cache_arena;
1031 static vmem_t           *kmem_hash_arena;
1032 static vmem_t           *kmem_log_arena;
1033 static vmem_t           *kmem_oversize_arena;
1034 static vmem_t           *kmem_va_arena;
1035 static vmem_t           *kmem_default_arena;
1036 static vmem_t           *kmem_firewall_va_arena;
1037 static vmem_t           *kmem_firewall_arena;
1038 
1039 /*
1040  * Define KMEM_STATS to turn on statistic gathering. By default, it is only
1041  * turned on when DEBUG is also defined.
1042  */
1043 #ifdef  DEBUG
1044 #define KMEM_STATS
1045 #endif  /* DEBUG */
1046 
1047 #ifdef  KMEM_STATS
1048 #define KMEM_STAT_ADD(stat)                     ((stat)++)
1049 #define KMEM_STAT_COND_ADD(cond, stat)          ((void) (!(cond) || (stat)++))
1050 #else
1051 #define KMEM_STAT_ADD(stat)                     /* nothing */
1052 #define KMEM_STAT_COND_ADD(cond, stat)          /* nothing */
1053 #endif  /* KMEM_STATS */
1054 
1055 /*
1056  * kmem slab consolidator thresholds (tunables)
1057  */
1058 size_t kmem_frag_minslabs = 101;        /* minimum total slabs */
1059 size_t kmem_frag_numer = 1;             /* free buffers (numerator) */
1060 size_t kmem_frag_denom = KMEM_VOID_FRACTION; /* buffers (denominator) */
1061 /*
1062  * Maximum number of slabs from which to move buffers during a single
1063  * maintenance interval while the system is not low on memory.
1064  */
1065 size_t kmem_reclaim_max_slabs = 1;
1066 /*
1067  * Number of slabs to scan backwards from the end of the partial slab list
1068  * when searching for buffers to relocate.
1069  */
1070 size_t kmem_reclaim_scan_range = 12;
1071 
1072 #ifdef  KMEM_STATS
1073 static struct {
1074         uint64_t kms_callbacks;
1075         uint64_t kms_yes;
1076         uint64_t kms_no;
1077         uint64_t kms_later;
1078         uint64_t kms_dont_need;
1079         uint64_t kms_dont_know;
1080         uint64_t kms_hunt_found_mag;
1081         uint64_t kms_hunt_found_slab;
1082         uint64_t kms_hunt_alloc_fail;
1083         uint64_t kms_hunt_lucky;
1084         uint64_t kms_notify;
1085         uint64_t kms_notify_callbacks;
1086         uint64_t kms_disbelief;
1087         uint64_t kms_already_pending;
1088         uint64_t kms_callback_alloc_fail;
1089         uint64_t kms_callback_taskq_fail;
1090         uint64_t kms_endscan_slab_dead;
1091         uint64_t kms_endscan_slab_destroyed;
1092         uint64_t kms_endscan_nomem;
1093         uint64_t kms_endscan_refcnt_changed;
1094         uint64_t kms_endscan_nomove_changed;
1095         uint64_t kms_endscan_freelist;
1096         uint64_t kms_avl_update;
1097         uint64_t kms_avl_noupdate;
1098         uint64_t kms_no_longer_reclaimable;
1099         uint64_t kms_notify_no_longer_reclaimable;
1100         uint64_t kms_notify_slab_dead;
1101         uint64_t kms_notify_slab_destroyed;
1102         uint64_t kms_alloc_fail;
1103         uint64_t kms_constructor_fail;
1104         uint64_t kms_dead_slabs_freed;
1105         uint64_t kms_defrags;
1106         uint64_t kms_scans;
1107         uint64_t kms_scan_depot_ws_reaps;
1108         uint64_t kms_debug_reaps;
1109         uint64_t kms_debug_scans;
1110 } kmem_move_stats;
1111 #endif  /* KMEM_STATS */
1112 
1113 /* consolidator knobs */
1114 static boolean_t kmem_move_noreap;
1115 static boolean_t kmem_move_blocked;
1116 static boolean_t kmem_move_fulltilt;
1117 static boolean_t kmem_move_any_partial;
1118 
1119 #ifdef  DEBUG
1120 /*
1121  * kmem consolidator debug tunables:
1122  * Ensure code coverage by occasionally running the consolidator even when the
1123  * caches are not fragmented (they may never be). These intervals are mean time
1124  * in cache maintenance intervals (kmem_cache_update).
1125  */
1126 uint32_t kmem_mtb_move = 60;    /* defrag 1 slab (~15min) */
1127 uint32_t kmem_mtb_reap = 1800;  /* defrag all slabs (~7.5hrs) */
1128 #endif  /* DEBUG */
1129 
1130 static kmem_cache_t     *kmem_defrag_cache;
1131 static kmem_cache_t     *kmem_move_cache;
1132 static taskq_t          *kmem_move_taskq;
1133 
1134 static void kmem_cache_scan(kmem_cache_t *);
1135 static void kmem_cache_defrag(kmem_cache_t *);
1136 static void kmem_slab_prefill(kmem_cache_t *, kmem_slab_t *);
1137 
1138 
1139 kmem_log_header_t       *kmem_transaction_log;
1140 kmem_log_header_t       *kmem_content_log;
1141 kmem_log_header_t       *kmem_failure_log;
1142 kmem_log_header_t       *kmem_slab_log;
1143 
1144 static int              kmem_lite_count; /* # of PCs in kmem_buftag_lite_t */
1145 
1146 #define KMEM_BUFTAG_LITE_ENTER(bt, count, caller)                       \
1147         if ((count) > 0) {                                           \
1148                 pc_t *_s = ((kmem_buftag_lite_t *)(bt))->bt_history; \
1149                 pc_t *_e;                                               \
1150                 /* memmove() the old entries down one notch */          \
1151                 for (_e = &_s[(count) - 1]; _e > _s; _e--)               \
1152                         *_e = *(_e - 1);                                \
1153                 *_s = (uintptr_t)(caller);                              \
1154         }
1155 
1156 #define KMERR_MODIFIED  0       /* buffer modified while on freelist */
1157 #define KMERR_REDZONE   1       /* redzone violation (write past end of buf) */
1158 #define KMERR_DUPFREE   2       /* freed a buffer twice */
1159 #define KMERR_BADADDR   3       /* freed a bad (unallocated) address */
1160 #define KMERR_BADBUFTAG 4       /* buftag corrupted */
1161 #define KMERR_BADBUFCTL 5       /* bufctl corrupted */
1162 #define KMERR_BADCACHE  6       /* freed a buffer to the wrong cache */
1163 #define KMERR_BADSIZE   7       /* alloc size != free size */
1164 #define KMERR_BADBASE   8       /* buffer base address wrong */
1165 
1166 struct {
1167         hrtime_t        kmp_timestamp;  /* timestamp of panic */
1168         int             kmp_error;      /* type of kmem error */
1169         void            *kmp_buffer;    /* buffer that induced panic */
1170         void            *kmp_realbuf;   /* real start address for buffer */
1171         kmem_cache_t    *kmp_cache;     /* buffer's cache according to client */
1172         kmem_cache_t    *kmp_realcache; /* actual cache containing buffer */
1173         kmem_slab_t     *kmp_slab;      /* slab accoring to kmem_findslab() */
1174         kmem_bufctl_t   *kmp_bufctl;    /* bufctl */
1175 } kmem_panic_info;
1176 
1177 
1178 static void
1179 copy_pattern(uint64_t pattern, void *buf_arg, size_t size)
1180 {
1181         uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1182         uint64_t *buf = buf_arg;
1183 
1184         while (buf < bufend)
1185                 *buf++ = pattern;
1186 }
1187 
1188 static void *
1189 verify_pattern(uint64_t pattern, void *buf_arg, size_t size)
1190 {
1191         uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1192         uint64_t *buf;
1193 
1194         for (buf = buf_arg; buf < bufend; buf++)
1195                 if (*buf != pattern)
1196                         return (buf);
1197         return (NULL);
1198 }
1199 
1200 static void *
1201 verify_and_copy_pattern(uint64_t old, uint64_t new, void *buf_arg, size_t size)
1202 {
1203         uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1204         uint64_t *buf;
1205 
1206         for (buf = buf_arg; buf < bufend; buf++) {
1207                 if (*buf != old) {
1208                         copy_pattern(old, buf_arg,
1209                             (char *)buf - (char *)buf_arg);
1210                         return (buf);
1211                 }
1212                 *buf = new;
1213         }
1214 
1215         return (NULL);
1216 }
1217 
1218 static void
1219 kmem_cache_applyall(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1220 {
1221         kmem_cache_t *cp;
1222 
1223         mutex_enter(&kmem_cache_lock);
1224         for (cp = list_head(&kmem_caches); cp != NULL;
1225             cp = list_next(&kmem_caches, cp))
1226                 if (tq != NULL)
1227                         (void) taskq_dispatch(tq, (task_func_t *)func, cp,
1228                             tqflag);
1229                 else
1230                         func(cp);
1231         mutex_exit(&kmem_cache_lock);
1232 }
1233 
1234 static void
1235 kmem_cache_applyall_id(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1236 {
1237         kmem_cache_t *cp;
1238 
1239         mutex_enter(&kmem_cache_lock);
1240         for (cp = list_head(&kmem_caches); cp != NULL;
1241             cp = list_next(&kmem_caches, cp)) {
1242                 if (!(cp->cache_cflags & KMC_IDENTIFIER))
1243                         continue;
1244                 if (tq != NULL)
1245                         (void) taskq_dispatch(tq, (task_func_t *)func, cp,
1246                             tqflag);
1247                 else
1248                         func(cp);
1249         }
1250         mutex_exit(&kmem_cache_lock);
1251 }
1252 
1253 /*
1254  * Debugging support.  Given a buffer address, find its slab.
1255  */
1256 static kmem_slab_t *
1257 kmem_findslab(kmem_cache_t *cp, void *buf)
1258 {
1259         kmem_slab_t *sp;
1260 
1261         mutex_enter(&cp->cache_lock);
1262         for (sp = list_head(&cp->cache_complete_slabs); sp != NULL;
1263             sp = list_next(&cp->cache_complete_slabs, sp)) {
1264                 if (KMEM_SLAB_MEMBER(sp, buf)) {
1265                         mutex_exit(&cp->cache_lock);
1266                         return (sp);
1267                 }
1268         }
1269         for (sp = avl_first(&cp->cache_partial_slabs); sp != NULL;
1270             sp = AVL_NEXT(&cp->cache_partial_slabs, sp)) {
1271                 if (KMEM_SLAB_MEMBER(sp, buf)) {
1272                         mutex_exit(&cp->cache_lock);
1273                         return (sp);
1274                 }
1275         }
1276         mutex_exit(&cp->cache_lock);
1277 
1278         return (NULL);
1279 }
1280 
1281 static void
1282 kmem_error(int error, kmem_cache_t *cparg, void *bufarg)
1283 {
1284         kmem_buftag_t *btp = NULL;
1285         kmem_bufctl_t *bcp = NULL;
1286         kmem_cache_t *cp = cparg;
1287         kmem_slab_t *sp;
1288         uint64_t *off;
1289         void *buf = bufarg;
1290 
1291         kmem_logging = 0;       /* stop logging when a bad thing happens */
1292 
1293         kmem_panic_info.kmp_timestamp = gethrtime();
1294 
1295         sp = kmem_findslab(cp, buf);
1296         if (sp == NULL) {
1297                 for (cp = list_tail(&kmem_caches); cp != NULL;
1298                     cp = list_prev(&kmem_caches, cp)) {
1299                         if ((sp = kmem_findslab(cp, buf)) != NULL)
1300                                 break;
1301                 }
1302         }
1303 
1304         if (sp == NULL) {
1305                 cp = NULL;
1306                 error = KMERR_BADADDR;
1307         } else {
1308                 if (cp != cparg)
1309                         error = KMERR_BADCACHE;
1310                 else
1311                         buf = (char *)bufarg - ((uintptr_t)bufarg -
1312                             (uintptr_t)sp->slab_base) % cp->cache_chunksize;
1313                 if (buf != bufarg)
1314                         error = KMERR_BADBASE;
1315                 if (cp->cache_flags & KMF_BUFTAG)
1316                         btp = KMEM_BUFTAG(cp, buf);
1317                 if (cp->cache_flags & KMF_HASH) {
1318                         mutex_enter(&cp->cache_lock);
1319                         for (bcp = *KMEM_HASH(cp, buf); bcp; bcp = bcp->bc_next)
1320                                 if (bcp->bc_addr == buf)
1321                                         break;
1322                         mutex_exit(&cp->cache_lock);
1323                         if (bcp == NULL && btp != NULL)
1324                                 bcp = btp->bt_bufctl;
1325                         if (kmem_findslab(cp->cache_bufctl_cache, bcp) ==
1326                             NULL || P2PHASE((uintptr_t)bcp, KMEM_ALIGN) ||
1327                             bcp->bc_addr != buf) {
1328                                 error = KMERR_BADBUFCTL;
1329                                 bcp = NULL;
1330                         }
1331                 }
1332         }
1333 
1334         kmem_panic_info.kmp_error = error;
1335         kmem_panic_info.kmp_buffer = bufarg;
1336         kmem_panic_info.kmp_realbuf = buf;
1337         kmem_panic_info.kmp_cache = cparg;
1338         kmem_panic_info.kmp_realcache = cp;
1339         kmem_panic_info.kmp_slab = sp;
1340         kmem_panic_info.kmp_bufctl = bcp;
1341 
1342         printf("kernel memory allocator: ");
1343 
1344         switch (error) {
1345 
1346         case KMERR_MODIFIED:
1347                 printf("buffer modified after being freed\n");
1348                 off = verify_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1349                 if (off == NULL)        /* shouldn't happen */
1350                         off = buf;
1351                 printf("modification occurred at offset 0x%lx "
1352                     "(0x%llx replaced by 0x%llx)\n",
1353                     (uintptr_t)off - (uintptr_t)buf,
1354                     (longlong_t)KMEM_FREE_PATTERN, (longlong_t)*off);
1355                 break;
1356 
1357         case KMERR_REDZONE:
1358                 printf("redzone violation: write past end of buffer\n");
1359                 break;
1360 
1361         case KMERR_BADADDR:
1362                 printf("invalid free: buffer not in cache\n");
1363                 break;
1364 
1365         case KMERR_DUPFREE:
1366                 printf("duplicate free: buffer freed twice\n");
1367                 break;
1368 
1369         case KMERR_BADBUFTAG:
1370                 printf("boundary tag corrupted\n");
1371                 printf("bcp ^ bxstat = %lx, should be %lx\n",
1372                     (intptr_t)btp->bt_bufctl ^ btp->bt_bxstat,
1373                     KMEM_BUFTAG_FREE);
1374                 break;
1375 
1376         case KMERR_BADBUFCTL:
1377                 printf("bufctl corrupted\n");
1378                 break;
1379 
1380         case KMERR_BADCACHE:
1381                 printf("buffer freed to wrong cache\n");
1382                 printf("buffer was allocated from %s,\n", cp->cache_name);
1383                 printf("caller attempting free to %s.\n", cparg->cache_name);
1384                 break;
1385 
1386         case KMERR_BADSIZE:
1387                 printf("bad free: free size (%u) != alloc size (%u)\n",
1388                     KMEM_SIZE_DECODE(((uint32_t *)btp)[0]),
1389                     KMEM_SIZE_DECODE(((uint32_t *)btp)[1]));
1390                 break;
1391 
1392         case KMERR_BADBASE:
1393                 printf("bad free: free address (%p) != alloc address (%p)\n",
1394                     bufarg, buf);
1395                 break;
1396         }
1397 
1398         printf("buffer=%p  bufctl=%p  cache: %s\n",
1399             bufarg, (void *)bcp, cparg->cache_name);
1400 
1401         if (bcp != NULL && (cp->cache_flags & KMF_AUDIT) &&
1402             error != KMERR_BADBUFCTL) {
1403                 int d;
1404                 timestruc_t ts;
1405                 kmem_bufctl_audit_t *bcap = (kmem_bufctl_audit_t *)bcp;
1406 
1407                 hrt2ts(kmem_panic_info.kmp_timestamp - bcap->bc_timestamp, &ts);
1408                 printf("previous transaction on buffer %p:\n", buf);
1409                 printf("thread=%p  time=T-%ld.%09ld  slab=%p  cache: %s\n",
1410                     (void *)bcap->bc_thread, ts.tv_sec, ts.tv_nsec,
1411                     (void *)sp, cp->cache_name);
1412                 for (d = 0; d < MIN(bcap->bc_depth, KMEM_STACK_DEPTH); d++) {
1413                         ulong_t off;
1414                         char *sym = kobj_getsymname(bcap->bc_stack[d], &off);
1415                         printf("%s+%lx\n", sym ? sym : "?", off);
1416                 }
1417         }
1418         if (kmem_panic > 0)
1419                 panic("kernel heap corruption detected");
1420         if (kmem_panic == 0)
1421                 debug_enter(NULL);
1422         kmem_logging = 1;       /* resume logging */
1423 }
1424 
1425 static kmem_log_header_t *
1426 kmem_log_init(size_t logsize)
1427 {
1428         kmem_log_header_t *lhp;
1429         int nchunks = 4 * max_ncpus;
1430         size_t lhsize = (size_t)&((kmem_log_header_t *)0)->lh_cpu[max_ncpus];
1431         int i;
1432 
1433         /*
1434          * Make sure that lhp->lh_cpu[] is nicely aligned
1435          * to prevent false sharing of cache lines.
1436          */
1437         lhsize = P2ROUNDUP(lhsize, KMEM_ALIGN);
1438         lhp = vmem_xalloc(kmem_log_arena, lhsize, 64, P2NPHASE(lhsize, 64), 0,
1439             NULL, NULL, VM_SLEEP);
1440         bzero(lhp, lhsize);
1441 
1442         mutex_init(&lhp->lh_lock, NULL, MUTEX_DEFAULT, NULL);
1443         lhp->lh_nchunks = nchunks;
1444         lhp->lh_chunksize = P2ROUNDUP(logsize / nchunks + 1, PAGESIZE);
1445         lhp->lh_base = vmem_alloc(kmem_log_arena,
1446             lhp->lh_chunksize * nchunks, VM_SLEEP);
1447         lhp->lh_free = vmem_alloc(kmem_log_arena,
1448             nchunks * sizeof (int), VM_SLEEP);
1449         bzero(lhp->lh_base, lhp->lh_chunksize * nchunks);
1450 
1451         for (i = 0; i < max_ncpus; i++) {
1452                 kmem_cpu_log_header_t *clhp = &lhp->lh_cpu[i];
1453                 mutex_init(&clhp->clh_lock, NULL, MUTEX_DEFAULT, NULL);
1454                 clhp->clh_chunk = i;
1455         }
1456 
1457         for (i = max_ncpus; i < nchunks; i++)
1458                 lhp->lh_free[i] = i;
1459 
1460         lhp->lh_head = max_ncpus;
1461         lhp->lh_tail = 0;
1462 
1463         return (lhp);
1464 }
1465 
1466 static void *
1467 kmem_log_enter(kmem_log_header_t *lhp, void *data, size_t size)
1468 {
1469         void *logspace;
1470         kmem_cpu_log_header_t *clhp = &lhp->lh_cpu[CPU->cpu_seqid];
1471 
1472         if (lhp == NULL || kmem_logging == 0 || panicstr)
1473                 return (NULL);
1474 
1475         mutex_enter(&clhp->clh_lock);
1476         clhp->clh_hits++;
1477         if (size > clhp->clh_avail) {
1478                 mutex_enter(&lhp->lh_lock);
1479                 lhp->lh_hits++;
1480                 lhp->lh_free[lhp->lh_tail] = clhp->clh_chunk;
1481                 lhp->lh_tail = (lhp->lh_tail + 1) % lhp->lh_nchunks;
1482                 clhp->clh_chunk = lhp->lh_free[lhp->lh_head];
1483                 lhp->lh_head = (lhp->lh_head + 1) % lhp->lh_nchunks;
1484                 clhp->clh_current = lhp->lh_base +
1485                     clhp->clh_chunk * lhp->lh_chunksize;
1486                 clhp->clh_avail = lhp->lh_chunksize;
1487                 if (size > lhp->lh_chunksize)
1488                         size = lhp->lh_chunksize;
1489                 mutex_exit(&lhp->lh_lock);
1490         }
1491         logspace = clhp->clh_current;
1492         clhp->clh_current += size;
1493         clhp->clh_avail -= size;
1494         bcopy(data, logspace, size);
1495         mutex_exit(&clhp->clh_lock);
1496         return (logspace);
1497 }
1498 
1499 #define KMEM_AUDIT(lp, cp, bcp)                                         \
1500 {                                                                       \
1501         kmem_bufctl_audit_t *_bcp = (kmem_bufctl_audit_t *)(bcp);       \
1502         _bcp->bc_timestamp = gethrtime();                            \
1503         _bcp->bc_thread = curthread;                                 \
1504         _bcp->bc_depth = getpcstack(_bcp->bc_stack, KMEM_STACK_DEPTH);    \
1505         _bcp->bc_lastlog = kmem_log_enter((lp), _bcp, sizeof (*_bcp));       \
1506 }
1507 
1508 static void
1509 kmem_log_event(kmem_log_header_t *lp, kmem_cache_t *cp,
1510         kmem_slab_t *sp, void *addr)
1511 {
1512         kmem_bufctl_audit_t bca;
1513 
1514         bzero(&bca, sizeof (kmem_bufctl_audit_t));
1515         bca.bc_addr = addr;
1516         bca.bc_slab = sp;
1517         bca.bc_cache = cp;
1518         KMEM_AUDIT(lp, cp, &bca);
1519 }
1520 
1521 /*
1522  * Create a new slab for cache cp.
1523  */
1524 static kmem_slab_t *
1525 kmem_slab_create(kmem_cache_t *cp, int kmflag)
1526 {
1527         size_t slabsize = cp->cache_slabsize;
1528         size_t chunksize = cp->cache_chunksize;
1529         int cache_flags = cp->cache_flags;
1530         size_t color, chunks;
1531         char *buf, *slab;
1532         kmem_slab_t *sp;
1533         kmem_bufctl_t *bcp;
1534         vmem_t *vmp = cp->cache_arena;
1535 
1536         ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1537 
1538         color = cp->cache_color + cp->cache_align;
1539         if (color > cp->cache_maxcolor)
1540                 color = cp->cache_mincolor;
1541         cp->cache_color = color;
1542 
1543         slab = vmem_alloc(vmp, slabsize, kmflag & KM_VMFLAGS);
1544 
1545         if (slab == NULL)
1546                 goto vmem_alloc_failure;
1547 
1548         ASSERT(P2PHASE((uintptr_t)slab, vmp->vm_quantum) == 0);
1549 
1550         /*
1551          * Reverify what was already checked in kmem_cache_set_move(), since the
1552          * consolidator depends (for correctness) on slabs being initialized
1553          * with the 0xbaddcafe memory pattern (setting a low order bit usable by
1554          * clients to distinguish uninitialized memory from known objects).
1555          */
1556         ASSERT((cp->cache_move == NULL) || !(cp->cache_cflags & KMC_NOTOUCH));
1557         if (!(cp->cache_cflags & KMC_NOTOUCH))
1558                 copy_pattern(KMEM_UNINITIALIZED_PATTERN, slab, slabsize);
1559 
1560         if (cache_flags & KMF_HASH) {
1561                 if ((sp = kmem_cache_alloc(kmem_slab_cache, kmflag)) == NULL)
1562                         goto slab_alloc_failure;
1563                 chunks = (slabsize - color) / chunksize;
1564         } else {
1565                 sp = KMEM_SLAB(cp, slab);
1566                 chunks = (slabsize - sizeof (kmem_slab_t) - color) / chunksize;
1567         }
1568 
1569         sp->slab_cache       = cp;
1570         sp->slab_head        = NULL;
1571         sp->slab_refcnt      = 0;
1572         sp->slab_base        = buf = slab + color;
1573         sp->slab_chunks      = chunks;
1574         sp->slab_stuck_offset = (uint32_t)-1;
1575         sp->slab_later_count = 0;
1576         sp->slab_flags = 0;
1577 
1578         ASSERT(chunks > 0);
1579         while (chunks-- != 0) {
1580                 if (cache_flags & KMF_HASH) {
1581                         bcp = kmem_cache_alloc(cp->cache_bufctl_cache, kmflag);
1582                         if (bcp == NULL)
1583                                 goto bufctl_alloc_failure;
1584                         if (cache_flags & KMF_AUDIT) {
1585                                 kmem_bufctl_audit_t *bcap =
1586                                     (kmem_bufctl_audit_t *)bcp;
1587                                 bzero(bcap, sizeof (kmem_bufctl_audit_t));
1588                                 bcap->bc_cache = cp;
1589                         }
1590                         bcp->bc_addr = buf;
1591                         bcp->bc_slab = sp;
1592                 } else {
1593                         bcp = KMEM_BUFCTL(cp, buf);
1594                 }
1595                 if (cache_flags & KMF_BUFTAG) {
1596                         kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1597                         btp->bt_redzone = KMEM_REDZONE_PATTERN;
1598                         btp->bt_bufctl = bcp;
1599                         btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1600                         if (cache_flags & KMF_DEADBEEF) {
1601                                 copy_pattern(KMEM_FREE_PATTERN, buf,
1602                                     cp->cache_verify);
1603                         }
1604                 }
1605                 bcp->bc_next = sp->slab_head;
1606                 sp->slab_head = bcp;
1607                 buf += chunksize;
1608         }
1609 
1610         kmem_log_event(kmem_slab_log, cp, sp, slab);
1611 
1612         return (sp);
1613 
1614 bufctl_alloc_failure:
1615 
1616         while ((bcp = sp->slab_head) != NULL) {
1617                 sp->slab_head = bcp->bc_next;
1618                 kmem_cache_free(cp->cache_bufctl_cache, bcp);
1619         }
1620         kmem_cache_free(kmem_slab_cache, sp);
1621 
1622 slab_alloc_failure:
1623 
1624         vmem_free(vmp, slab, slabsize);
1625 
1626 vmem_alloc_failure:
1627 
1628         kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1629         atomic_inc_64(&cp->cache_alloc_fail);
1630 
1631         return (NULL);
1632 }
1633 
1634 /*
1635  * Destroy a slab.
1636  */
1637 static void
1638 kmem_slab_destroy(kmem_cache_t *cp, kmem_slab_t *sp)
1639 {
1640         vmem_t *vmp = cp->cache_arena;
1641         void *slab = (void *)P2ALIGN((uintptr_t)sp->slab_base, vmp->vm_quantum);
1642 
1643         ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1644         ASSERT(sp->slab_refcnt == 0);
1645 
1646         if (cp->cache_flags & KMF_HASH) {
1647                 kmem_bufctl_t *bcp;
1648                 while ((bcp = sp->slab_head) != NULL) {
1649                         sp->slab_head = bcp->bc_next;
1650                         kmem_cache_free(cp->cache_bufctl_cache, bcp);
1651                 }
1652                 kmem_cache_free(kmem_slab_cache, sp);
1653         }
1654         vmem_free(vmp, slab, cp->cache_slabsize);
1655 }
1656 
1657 static void *
1658 kmem_slab_alloc_impl(kmem_cache_t *cp, kmem_slab_t *sp, boolean_t prefill)
1659 {
1660         kmem_bufctl_t *bcp, **hash_bucket;
1661         void *buf;
1662         boolean_t new_slab = (sp->slab_refcnt == 0);
1663 
1664         ASSERT(MUTEX_HELD(&cp->cache_lock));
1665         /*
1666          * kmem_slab_alloc() drops cache_lock when it creates a new slab, so we
1667          * can't ASSERT(avl_is_empty(&cp->cache_partial_slabs)) here when the
1668          * slab is newly created.
1669          */
1670         ASSERT(new_slab || (KMEM_SLAB_IS_PARTIAL(sp) &&
1671             (sp == avl_first(&cp->cache_partial_slabs))));
1672         ASSERT(sp->slab_cache == cp);
1673 
1674         cp->cache_slab_alloc++;
1675         cp->cache_bufslab--;
1676         sp->slab_refcnt++;
1677 
1678         bcp = sp->slab_head;
1679         sp->slab_head = bcp->bc_next;
1680 
1681         if (cp->cache_flags & KMF_HASH) {
1682                 /*
1683                  * Add buffer to allocated-address hash table.
1684                  */
1685                 buf = bcp->bc_addr;
1686                 hash_bucket = KMEM_HASH(cp, buf);
1687                 bcp->bc_next = *hash_bucket;
1688                 *hash_bucket = bcp;
1689                 if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1690                         KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1691                 }
1692         } else {
1693                 buf = KMEM_BUF(cp, bcp);
1694         }
1695 
1696         ASSERT(KMEM_SLAB_MEMBER(sp, buf));
1697 
1698         if (sp->slab_head == NULL) {
1699                 ASSERT(KMEM_SLAB_IS_ALL_USED(sp));
1700                 if (new_slab) {
1701                         ASSERT(sp->slab_chunks == 1);
1702                 } else {
1703                         ASSERT(sp->slab_chunks > 1); /* the slab was partial */
1704                         avl_remove(&cp->cache_partial_slabs, sp);
1705                         sp->slab_later_count = 0; /* clear history */
1706                         sp->slab_flags &= ~KMEM_SLAB_NOMOVE;
1707                         sp->slab_stuck_offset = (uint32_t)-1;
1708                 }
1709                 list_insert_head(&cp->cache_complete_slabs, sp);
1710                 cp->cache_complete_slab_count++;
1711                 return (buf);
1712         }
1713 
1714         ASSERT(KMEM_SLAB_IS_PARTIAL(sp));
1715         /*
1716          * Peek to see if the magazine layer is enabled before
1717          * we prefill.  We're not holding the cpu cache lock,
1718          * so the peek could be wrong, but there's no harm in it.
1719          */
1720         if (new_slab && prefill && (cp->cache_flags & KMF_PREFILL) &&
1721             (KMEM_CPU_CACHE(cp)->cc_magsize != 0))  {
1722                 kmem_slab_prefill(cp, sp);
1723                 return (buf);
1724         }
1725 
1726         if (new_slab) {
1727                 avl_add(&cp->cache_partial_slabs, sp);
1728                 return (buf);
1729         }
1730 
1731         /*
1732          * The slab is now more allocated than it was, so the
1733          * order remains unchanged.
1734          */
1735         ASSERT(!avl_update(&cp->cache_partial_slabs, sp));
1736         return (buf);
1737 }
1738 
1739 /*
1740  * Allocate a raw (unconstructed) buffer from cp's slab layer.
1741  */
1742 static void *
1743 kmem_slab_alloc(kmem_cache_t *cp, int kmflag)
1744 {
1745         kmem_slab_t *sp;
1746         void *buf;
1747         boolean_t test_destructor;
1748 
1749         mutex_enter(&cp->cache_lock);
1750         test_destructor = (cp->cache_slab_alloc == 0);
1751         sp = avl_first(&cp->cache_partial_slabs);
1752         if (sp == NULL) {
1753                 ASSERT(cp->cache_bufslab == 0);
1754 
1755                 /*
1756                  * The freelist is empty.  Create a new slab.
1757                  */
1758                 mutex_exit(&cp->cache_lock);
1759                 if ((sp = kmem_slab_create(cp, kmflag)) == NULL) {
1760                         return (NULL);
1761                 }
1762                 mutex_enter(&cp->cache_lock);
1763                 cp->cache_slab_create++;
1764                 if ((cp->cache_buftotal += sp->slab_chunks) > cp->cache_bufmax)
1765                         cp->cache_bufmax = cp->cache_buftotal;
1766                 cp->cache_bufslab += sp->slab_chunks;
1767         }
1768 
1769         buf = kmem_slab_alloc_impl(cp, sp, B_TRUE);
1770         ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1771             (cp->cache_complete_slab_count +
1772             avl_numnodes(&cp->cache_partial_slabs) +
1773             (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1774         mutex_exit(&cp->cache_lock);
1775 
1776         if (test_destructor && cp->cache_destructor != NULL) {
1777                 /*
1778                  * On the first kmem_slab_alloc(), assert that it is valid to
1779                  * call the destructor on a newly constructed object without any
1780                  * client involvement.
1781                  */
1782                 if ((cp->cache_constructor == NULL) ||
1783                     cp->cache_constructor(buf, cp->cache_private,
1784                     kmflag) == 0) {
1785                         cp->cache_destructor(buf, cp->cache_private);
1786                 }
1787                 copy_pattern(KMEM_UNINITIALIZED_PATTERN, buf,
1788                     cp->cache_bufsize);
1789                 if (cp->cache_flags & KMF_DEADBEEF) {
1790                         copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1791                 }
1792         }
1793 
1794         return (buf);
1795 }
1796 
1797 static void kmem_slab_move_yes(kmem_cache_t *, kmem_slab_t *, void *);
1798 
1799 /*
1800  * Free a raw (unconstructed) buffer to cp's slab layer.
1801  */
1802 static void
1803 kmem_slab_free(kmem_cache_t *cp, void *buf)
1804 {
1805         kmem_slab_t *sp;
1806         kmem_bufctl_t *bcp, **prev_bcpp;
1807 
1808         ASSERT(buf != NULL);
1809 
1810         mutex_enter(&cp->cache_lock);
1811         cp->cache_slab_free++;
1812 
1813         if (cp->cache_flags & KMF_HASH) {
1814                 /*
1815                  * Look up buffer in allocated-address hash table.
1816                  */
1817                 prev_bcpp = KMEM_HASH(cp, buf);
1818                 while ((bcp = *prev_bcpp) != NULL) {
1819                         if (bcp->bc_addr == buf) {
1820                                 *prev_bcpp = bcp->bc_next;
1821                                 sp = bcp->bc_slab;
1822                                 break;
1823                         }
1824                         cp->cache_lookup_depth++;
1825                         prev_bcpp = &bcp->bc_next;
1826                 }
1827         } else {
1828                 bcp = KMEM_BUFCTL(cp, buf);
1829                 sp = KMEM_SLAB(cp, buf);
1830         }
1831 
1832         if (bcp == NULL || sp->slab_cache != cp || !KMEM_SLAB_MEMBER(sp, buf)) {
1833                 mutex_exit(&cp->cache_lock);
1834                 kmem_error(KMERR_BADADDR, cp, buf);
1835                 return;
1836         }
1837 
1838         if (KMEM_SLAB_OFFSET(sp, buf) == sp->slab_stuck_offset) {
1839                 /*
1840                  * If this is the buffer that prevented the consolidator from
1841                  * clearing the slab, we can reset the slab flags now that the
1842                  * buffer is freed. (It makes sense to do this in
1843                  * kmem_cache_free(), where the client gives up ownership of the
1844                  * buffer, but on the hot path the test is too expensive.)
1845                  */
1846                 kmem_slab_move_yes(cp, sp, buf);
1847         }
1848 
1849         if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1850                 if (cp->cache_flags & KMF_CONTENTS)
1851                         ((kmem_bufctl_audit_t *)bcp)->bc_contents =
1852                             kmem_log_enter(kmem_content_log, buf,
1853                             cp->cache_contents);
1854                 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1855         }
1856 
1857         bcp->bc_next = sp->slab_head;
1858         sp->slab_head = bcp;
1859 
1860         cp->cache_bufslab++;
1861         ASSERT(sp->slab_refcnt >= 1);
1862 
1863         if (--sp->slab_refcnt == 0) {
1864                 /*
1865                  * There are no outstanding allocations from this slab,
1866                  * so we can reclaim the memory.
1867                  */
1868                 if (sp->slab_chunks == 1) {
1869                         list_remove(&cp->cache_complete_slabs, sp);
1870                         cp->cache_complete_slab_count--;
1871                 } else {
1872                         avl_remove(&cp->cache_partial_slabs, sp);
1873                 }
1874 
1875                 cp->cache_buftotal -= sp->slab_chunks;
1876                 cp->cache_bufslab -= sp->slab_chunks;
1877                 /*
1878                  * Defer releasing the slab to the virtual memory subsystem
1879                  * while there is a pending move callback, since we guarantee
1880                  * that buffers passed to the move callback have only been
1881                  * touched by kmem or by the client itself. Since the memory
1882                  * patterns baddcafe (uninitialized) and deadbeef (freed) both
1883                  * set at least one of the two lowest order bits, the client can
1884                  * test those bits in the move callback to determine whether or
1885                  * not it knows about the buffer (assuming that the client also
1886                  * sets one of those low order bits whenever it frees a buffer).
1887                  */
1888                 if (cp->cache_defrag == NULL ||
1889                     (avl_is_empty(&cp->cache_defrag->kmd_moves_pending) &&
1890                     !(sp->slab_flags & KMEM_SLAB_MOVE_PENDING))) {
1891                         cp->cache_slab_destroy++;
1892                         mutex_exit(&cp->cache_lock);
1893                         kmem_slab_destroy(cp, sp);
1894                 } else {
1895                         list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
1896                         /*
1897                          * Slabs are inserted at both ends of the deadlist to
1898                          * distinguish between slabs freed while move callbacks
1899                          * are pending (list head) and a slab freed while the
1900                          * lock is dropped in kmem_move_buffers() (list tail) so
1901                          * that in both cases slab_destroy() is called from the
1902                          * right context.
1903                          */
1904                         if (sp->slab_flags & KMEM_SLAB_MOVE_PENDING) {
1905                                 list_insert_tail(deadlist, sp);
1906                         } else {
1907                                 list_insert_head(deadlist, sp);
1908                         }
1909                         cp->cache_defrag->kmd_deadcount++;
1910                         mutex_exit(&cp->cache_lock);
1911                 }
1912                 return;
1913         }
1914 
1915         if (bcp->bc_next == NULL) {
1916                 /* Transition the slab from completely allocated to partial. */
1917                 ASSERT(sp->slab_refcnt == (sp->slab_chunks - 1));
1918                 ASSERT(sp->slab_chunks > 1);
1919                 list_remove(&cp->cache_complete_slabs, sp);
1920                 cp->cache_complete_slab_count--;
1921                 avl_add(&cp->cache_partial_slabs, sp);
1922         } else {
1923 #ifdef  DEBUG
1924                 if (avl_update_gt(&cp->cache_partial_slabs, sp)) {
1925                         KMEM_STAT_ADD(kmem_move_stats.kms_avl_update);
1926                 } else {
1927                         KMEM_STAT_ADD(kmem_move_stats.kms_avl_noupdate);
1928                 }
1929 #else
1930                 (void) avl_update_gt(&cp->cache_partial_slabs, sp);
1931 #endif
1932         }
1933 
1934         ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1935             (cp->cache_complete_slab_count +
1936             avl_numnodes(&cp->cache_partial_slabs) +
1937             (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1938         mutex_exit(&cp->cache_lock);
1939 }
1940 
1941 /*
1942  * Return -1 if kmem_error, 1 if constructor fails, 0 if successful.
1943  */
1944 static int
1945 kmem_cache_alloc_debug(kmem_cache_t *cp, void *buf, int kmflag, int construct,
1946     caddr_t caller)
1947 {
1948         kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1949         kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
1950         uint32_t mtbf;
1951 
1952         if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
1953                 kmem_error(KMERR_BADBUFTAG, cp, buf);
1954                 return (-1);
1955         }
1956 
1957         btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_ALLOC;
1958 
1959         if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
1960                 kmem_error(KMERR_BADBUFCTL, cp, buf);
1961                 return (-1);
1962         }
1963 
1964         if (cp->cache_flags & KMF_DEADBEEF) {
1965                 if (!construct && (cp->cache_flags & KMF_LITE)) {
1966                         if (*(uint64_t *)buf != KMEM_FREE_PATTERN) {
1967                                 kmem_error(KMERR_MODIFIED, cp, buf);
1968                                 return (-1);
1969                         }
1970                         if (cp->cache_constructor != NULL)
1971                                 *(uint64_t *)buf = btp->bt_redzone;
1972                         else
1973                                 *(uint64_t *)buf = KMEM_UNINITIALIZED_PATTERN;
1974                 } else {
1975                         construct = 1;
1976                         if (verify_and_copy_pattern(KMEM_FREE_PATTERN,
1977                             KMEM_UNINITIALIZED_PATTERN, buf,
1978                             cp->cache_verify)) {
1979                                 kmem_error(KMERR_MODIFIED, cp, buf);
1980                                 return (-1);
1981                         }
1982                 }
1983         }
1984         btp->bt_redzone = KMEM_REDZONE_PATTERN;
1985 
1986         if ((mtbf = kmem_mtbf | cp->cache_mtbf) != 0 &&
1987             gethrtime() % mtbf == 0 &&
1988             (kmflag & (KM_NOSLEEP | KM_PANIC)) == KM_NOSLEEP) {
1989                 kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1990                 if (!construct && cp->cache_destructor != NULL)
1991                         cp->cache_destructor(buf, cp->cache_private);
1992         } else {
1993                 mtbf = 0;
1994         }
1995 
1996         if (mtbf || (construct && cp->cache_constructor != NULL &&
1997             cp->cache_constructor(buf, cp->cache_private, kmflag) != 0)) {
1998                 atomic_inc_64(&cp->cache_alloc_fail);
1999                 btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
2000                 if (cp->cache_flags & KMF_DEADBEEF)
2001                         copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
2002                 kmem_slab_free(cp, buf);
2003                 return (1);
2004         }
2005 
2006         if (cp->cache_flags & KMF_AUDIT) {
2007                 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
2008         }
2009 
2010         if ((cp->cache_flags & KMF_LITE) &&
2011             !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
2012                 KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
2013         }
2014 
2015         return (0);
2016 }
2017 
2018 static int
2019 kmem_cache_free_debug(kmem_cache_t *cp, void *buf, caddr_t caller)
2020 {
2021         kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2022         kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
2023         kmem_slab_t *sp;
2024 
2025         if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_ALLOC)) {
2026                 if (btp->bt_bxstat == ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
2027                         kmem_error(KMERR_DUPFREE, cp, buf);
2028                         return (-1);
2029                 }
2030                 sp = kmem_findslab(cp, buf);
2031                 if (sp == NULL || sp->slab_cache != cp)
2032                         kmem_error(KMERR_BADADDR, cp, buf);
2033                 else
2034                         kmem_error(KMERR_REDZONE, cp, buf);
2035                 return (-1);
2036         }
2037 
2038         btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
2039 
2040         if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
2041                 kmem_error(KMERR_BADBUFCTL, cp, buf);
2042                 return (-1);
2043         }
2044 
2045         if (btp->bt_redzone != KMEM_REDZONE_PATTERN) {
2046                 kmem_error(KMERR_REDZONE, cp, buf);
2047                 return (-1);
2048         }
2049 
2050         if (cp->cache_flags & KMF_AUDIT) {
2051                 if (cp->cache_flags & KMF_CONTENTS)
2052                         bcp->bc_contents = kmem_log_enter(kmem_content_log,
2053                             buf, cp->cache_contents);
2054                 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
2055         }
2056 
2057         if ((cp->cache_flags & KMF_LITE) &&
2058             !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
2059                 KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
2060         }
2061 
2062         if (cp->cache_flags & KMF_DEADBEEF) {
2063                 if (cp->cache_flags & KMF_LITE)
2064                         btp->bt_redzone = *(uint64_t *)buf;
2065                 else if (cp->cache_destructor != NULL)
2066                         cp->cache_destructor(buf, cp->cache_private);
2067 
2068                 copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
2069         }
2070 
2071         return (0);
2072 }
2073 
2074 /*
2075  * Free each object in magazine mp to cp's slab layer, and free mp itself.
2076  */
2077 static void
2078 kmem_magazine_destroy(kmem_cache_t *cp, kmem_magazine_t *mp, int nrounds)
2079 {
2080         int round;
2081 
2082         ASSERT(!list_link_active(&cp->cache_link) ||
2083             taskq_member(kmem_taskq, curthread));
2084 
2085         for (round = 0; round < nrounds; round++) {
2086                 void *buf = mp->mag_round[round];
2087 
2088                 if (cp->cache_flags & KMF_DEADBEEF) {
2089                         if (verify_pattern(KMEM_FREE_PATTERN, buf,
2090                             cp->cache_verify) != NULL) {
2091                                 kmem_error(KMERR_MODIFIED, cp, buf);
2092                                 continue;
2093                         }
2094                         if ((cp->cache_flags & KMF_LITE) &&
2095                             cp->cache_destructor != NULL) {
2096                                 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2097                                 *(uint64_t *)buf = btp->bt_redzone;
2098                                 cp->cache_destructor(buf, cp->cache_private);
2099                                 *(uint64_t *)buf = KMEM_FREE_PATTERN;
2100                         }
2101                 } else if (cp->cache_destructor != NULL) {
2102                         cp->cache_destructor(buf, cp->cache_private);
2103                 }
2104 
2105                 kmem_slab_free(cp, buf);
2106         }
2107         ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2108         kmem_cache_free(cp->cache_magtype->mt_cache, mp);
2109 }
2110 
2111 /*
2112  * Allocate a magazine from the depot.
2113  */
2114 static kmem_magazine_t *
2115 kmem_depot_alloc(kmem_cache_t *cp, kmem_maglist_t *mlp)
2116 {
2117         kmem_magazine_t *mp;
2118 
2119         /*
2120          * If we can't get the depot lock without contention,
2121          * update our contention count.  We use the depot
2122          * contention rate to determine whether we need to
2123          * increase the magazine size for better scalability.
2124          */
2125         if (!mutex_tryenter(&cp->cache_depot_lock)) {
2126                 mutex_enter(&cp->cache_depot_lock);
2127                 cp->cache_depot_contention++;
2128         }
2129 
2130         if ((mp = mlp->ml_list) != NULL) {
2131                 ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2132                 mlp->ml_list = mp->mag_next;
2133                 if (--mlp->ml_total < mlp->ml_min)
2134                         mlp->ml_min = mlp->ml_total;
2135                 mlp->ml_alloc++;
2136         }
2137 
2138         mutex_exit(&cp->cache_depot_lock);
2139 
2140         return (mp);
2141 }
2142 
2143 /*
2144  * Free a magazine to the depot.
2145  */
2146 static void
2147 kmem_depot_free(kmem_cache_t *cp, kmem_maglist_t *mlp, kmem_magazine_t *mp)
2148 {
2149         mutex_enter(&cp->cache_depot_lock);
2150         ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2151         mp->mag_next = mlp->ml_list;
2152         mlp->ml_list = mp;
2153         mlp->ml_total++;
2154         mutex_exit(&cp->cache_depot_lock);
2155 }
2156 
2157 /*
2158  * Update the working set statistics for cp's depot.
2159  */
2160 static void
2161 kmem_depot_ws_update(kmem_cache_t *cp)
2162 {
2163         mutex_enter(&cp->cache_depot_lock);
2164         cp->cache_full.ml_reaplimit = cp->cache_full.ml_min;
2165         cp->cache_full.ml_min = cp->cache_full.ml_total;
2166         cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_min;
2167         cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2168         mutex_exit(&cp->cache_depot_lock);
2169 }
2170 
2171 /*
2172  * Reap all magazines that have fallen out of the depot's working set.
2173  */
2174 static void
2175 kmem_depot_ws_reap(kmem_cache_t *cp)
2176 {
2177         long reap;
2178         kmem_magazine_t *mp;
2179 
2180         ASSERT(!list_link_active(&cp->cache_link) ||
2181             taskq_member(kmem_taskq, curthread));
2182 
2183         reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
2184         while (reap-- && (mp = kmem_depot_alloc(cp, &cp->cache_full)) != NULL)
2185                 kmem_magazine_destroy(cp, mp, cp->cache_magtype->mt_magsize);
2186 
2187         reap = MIN(cp->cache_empty.ml_reaplimit, cp->cache_empty.ml_min);
2188         while (reap-- && (mp = kmem_depot_alloc(cp, &cp->cache_empty)) != NULL)
2189                 kmem_magazine_destroy(cp, mp, 0);
2190 }
2191 
2192 static void
2193 kmem_cpu_reload(kmem_cpu_cache_t *ccp, kmem_magazine_t *mp, int rounds)
2194 {
2195         ASSERT((ccp->cc_loaded == NULL && ccp->cc_rounds == -1) ||
2196             (ccp->cc_loaded && ccp->cc_rounds + rounds == ccp->cc_magsize));
2197         ASSERT(ccp->cc_magsize > 0);
2198 
2199         ccp->cc_ploaded = ccp->cc_loaded;
2200         ccp->cc_prounds = ccp->cc_rounds;
2201         ccp->cc_loaded = mp;
2202         ccp->cc_rounds = rounds;
2203 }
2204 
2205 /*
2206  * Intercept kmem alloc/free calls during crash dump in order to avoid
2207  * changing kmem state while memory is being saved to the dump device.
2208  * Otherwise, ::kmem_verify will report "corrupt buffers".  Note that
2209  * there are no locks because only one CPU calls kmem during a crash
2210  * dump. To enable this feature, first create the associated vmem
2211  * arena with VMC_DUMPSAFE.
2212  */
2213 static void *kmem_dump_start;   /* start of pre-reserved heap */
2214 static void *kmem_dump_end;     /* end of heap area */
2215 static void *kmem_dump_curr;    /* current free heap pointer */
2216 static size_t kmem_dump_size;   /* size of heap area */
2217 
2218 /* append to each buf created in the pre-reserved heap */
2219 typedef struct kmem_dumpctl {
2220         void    *kdc_next;      /* cache dump free list linkage */
2221 } kmem_dumpctl_t;
2222 
2223 #define KMEM_DUMPCTL(cp, buf)   \
2224         ((kmem_dumpctl_t *)P2ROUNDUP((uintptr_t)(buf) + (cp)->cache_bufsize, \
2225             sizeof (void *)))
2226 
2227 /* Keep some simple stats. */
2228 #define KMEM_DUMP_LOGS  (100)
2229 
2230 typedef struct kmem_dump_log {
2231         kmem_cache_t    *kdl_cache;
2232         uint_t          kdl_allocs;             /* # of dump allocations */
2233         uint_t          kdl_frees;              /* # of dump frees */
2234         uint_t          kdl_alloc_fails;        /* # of allocation failures */
2235         uint_t          kdl_free_nondump;       /* # of non-dump frees */
2236         uint_t          kdl_unsafe;             /* cache was used, but unsafe */
2237 } kmem_dump_log_t;
2238 
2239 static kmem_dump_log_t *kmem_dump_log;
2240 static int kmem_dump_log_idx;
2241 
2242 #define KDI_LOG(cp, stat) {                                             \
2243         kmem_dump_log_t *kdl;                                           \
2244         if ((kdl = (kmem_dump_log_t *)((cp)->cache_dumplog)) != NULL) {      \
2245                 kdl->stat++;                                         \
2246         } else if (kmem_dump_log_idx < KMEM_DUMP_LOGS) {             \
2247                 kdl = &kmem_dump_log[kmem_dump_log_idx++];          \
2248                 kdl->stat++;                                         \
2249                 kdl->kdl_cache = (cp);                                       \
2250                 (cp)->cache_dumplog = kdl;                           \
2251         }                                                               \
2252 }
2253 
2254 /* set non zero for full report */
2255 uint_t kmem_dump_verbose = 0;
2256 
2257 /* stats for overize heap */
2258 uint_t kmem_dump_oversize_allocs = 0;
2259 uint_t kmem_dump_oversize_max = 0;
2260 
2261 static void
2262 kmem_dumppr(char **pp, char *e, const char *format, ...)
2263 {
2264         char *p = *pp;
2265 
2266         if (p < e) {
2267                 int n;
2268                 va_list ap;
2269 
2270                 va_start(ap, format);
2271                 n = vsnprintf(p, e - p, format, ap);
2272                 va_end(ap);
2273                 *pp = p + n;
2274         }
2275 }
2276 
2277 /*
2278  * Called when dumpadm(1M) configures dump parameters.
2279  */
2280 void
2281 kmem_dump_init(size_t size)
2282 {
2283         if (kmem_dump_start != NULL)
2284                 kmem_free(kmem_dump_start, kmem_dump_size);
2285 
2286         if (kmem_dump_log == NULL)
2287                 kmem_dump_log = (kmem_dump_log_t *)kmem_zalloc(KMEM_DUMP_LOGS *
2288                     sizeof (kmem_dump_log_t), KM_SLEEP);
2289 
2290         kmem_dump_start = kmem_alloc(size, KM_SLEEP);
2291 
2292         if (kmem_dump_start != NULL) {
2293                 kmem_dump_size = size;
2294                 kmem_dump_curr = kmem_dump_start;
2295                 kmem_dump_end = (void *)((char *)kmem_dump_start + size);
2296                 copy_pattern(KMEM_UNINITIALIZED_PATTERN, kmem_dump_start, size);
2297         } else {
2298                 kmem_dump_size = 0;
2299                 kmem_dump_curr = NULL;
2300                 kmem_dump_end = NULL;
2301         }
2302 }
2303 
2304 /*
2305  * Set flag for each kmem_cache_t if is safe to use alternate dump
2306  * memory. Called just before panic crash dump starts. Set the flag
2307  * for the calling CPU.
2308  */
2309 void
2310 kmem_dump_begin(void)
2311 {
2312         ASSERT(panicstr != NULL);
2313         if (kmem_dump_start != NULL) {
2314                 kmem_cache_t *cp;
2315 
2316                 for (cp = list_head(&kmem_caches); cp != NULL;
2317                     cp = list_next(&kmem_caches, cp)) {
2318                         kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2319 
2320                         if (cp->cache_arena->vm_cflags & VMC_DUMPSAFE) {
2321                                 cp->cache_flags |= KMF_DUMPDIVERT;
2322                                 ccp->cc_flags |= KMF_DUMPDIVERT;
2323                                 ccp->cc_dump_rounds = ccp->cc_rounds;
2324                                 ccp->cc_dump_prounds = ccp->cc_prounds;
2325                                 ccp->cc_rounds = ccp->cc_prounds = -1;
2326                         } else {
2327                                 cp->cache_flags |= KMF_DUMPUNSAFE;
2328                                 ccp->cc_flags |= KMF_DUMPUNSAFE;
2329                         }
2330                 }
2331         }
2332 }
2333 
2334 /*
2335  * finished dump intercept
2336  * print any warnings on the console
2337  * return verbose information to dumpsys() in the given buffer
2338  */
2339 size_t
2340 kmem_dump_finish(char *buf, size_t size)
2341 {
2342         int kdi_idx;
2343         int kdi_end = kmem_dump_log_idx;
2344         int percent = 0;
2345         int header = 0;
2346         int warn = 0;
2347         size_t used;
2348         kmem_cache_t *cp;
2349         kmem_dump_log_t *kdl;
2350         char *e = buf + size;
2351         char *p = buf;
2352 
2353         if (kmem_dump_size == 0 || kmem_dump_verbose == 0)
2354                 return (0);
2355 
2356         used = (char *)kmem_dump_curr - (char *)kmem_dump_start;
2357         percent = (used * 100) / kmem_dump_size;
2358 
2359         kmem_dumppr(&p, e, "%% heap used,%d\n", percent);
2360         kmem_dumppr(&p, e, "used bytes,%ld\n", used);
2361         kmem_dumppr(&p, e, "heap size,%ld\n", kmem_dump_size);
2362         kmem_dumppr(&p, e, "Oversize allocs,%d\n",
2363             kmem_dump_oversize_allocs);
2364         kmem_dumppr(&p, e, "Oversize max size,%ld\n",
2365             kmem_dump_oversize_max);
2366 
2367         for (kdi_idx = 0; kdi_idx < kdi_end; kdi_idx++) {
2368                 kdl = &kmem_dump_log[kdi_idx];
2369                 cp = kdl->kdl_cache;
2370                 if (cp == NULL)
2371                         break;
2372                 if (kdl->kdl_alloc_fails)
2373                         ++warn;
2374                 if (header == 0) {
2375                         kmem_dumppr(&p, e,
2376                             "Cache Name,Allocs,Frees,Alloc Fails,"
2377                             "Nondump Frees,Unsafe Allocs/Frees\n");
2378                         header = 1;
2379                 }
2380                 kmem_dumppr(&p, e, "%s,%d,%d,%d,%d,%d\n",
2381                     cp->cache_name, kdl->kdl_allocs, kdl->kdl_frees,
2382                     kdl->kdl_alloc_fails, kdl->kdl_free_nondump,
2383                     kdl->kdl_unsafe);
2384         }
2385 
2386         /* return buffer size used */
2387         if (p < e)
2388                 bzero(p, e - p);
2389         return (p - buf);
2390 }
2391 
2392 /*
2393  * Allocate a constructed object from alternate dump memory.
2394  */
2395 void *
2396 kmem_cache_alloc_dump(kmem_cache_t *cp, int kmflag)
2397 {
2398         void *buf;
2399         void *curr;
2400         char *bufend;
2401 
2402         /* return a constructed object */
2403         if ((buf = cp->cache_dumpfreelist) != NULL) {
2404                 cp->cache_dumpfreelist = KMEM_DUMPCTL(cp, buf)->kdc_next;
2405                 KDI_LOG(cp, kdl_allocs);
2406                 return (buf);
2407         }
2408 
2409         /* create a new constructed object */
2410         curr = kmem_dump_curr;
2411         buf = (void *)P2ROUNDUP((uintptr_t)curr, cp->cache_align);
2412         bufend = (char *)KMEM_DUMPCTL(cp, buf) + sizeof (kmem_dumpctl_t);
2413 
2414         /* hat layer objects cannot cross a page boundary */
2415         if (cp->cache_align < PAGESIZE) {
2416                 char *page = (char *)P2ROUNDUP((uintptr_t)buf, PAGESIZE);
2417                 if (bufend > page) {
2418                         bufend += page - (char *)buf;
2419                         buf = (void *)page;
2420                 }
2421         }
2422 
2423         /* fall back to normal alloc if reserved area is used up */
2424         if (bufend > (char *)kmem_dump_end) {
2425                 kmem_dump_curr = kmem_dump_end;
2426                 KDI_LOG(cp, kdl_alloc_fails);
2427                 return (NULL);
2428         }
2429 
2430         /*
2431          * Must advance curr pointer before calling a constructor that
2432          * may also allocate memory.
2433          */
2434         kmem_dump_curr = bufend;
2435 
2436         /* run constructor */
2437         if (cp->cache_constructor != NULL &&
2438             cp->cache_constructor(buf, cp->cache_private, kmflag)
2439             != 0) {
2440 #ifdef DEBUG
2441                 printf("name='%s' cache=0x%p: kmem cache constructor failed\n",
2442                     cp->cache_name, (void *)cp);
2443 #endif
2444                 /* reset curr pointer iff no allocs were done */
2445                 if (kmem_dump_curr == bufend)
2446                         kmem_dump_curr = curr;
2447 
2448                 /* fall back to normal alloc if the constructor fails */
2449                 KDI_LOG(cp, kdl_alloc_fails);
2450                 return (NULL);
2451         }
2452 
2453         KDI_LOG(cp, kdl_allocs);
2454         return (buf);
2455 }
2456 
2457 /*
2458  * Free a constructed object in alternate dump memory.
2459  */
2460 int
2461 kmem_cache_free_dump(kmem_cache_t *cp, void *buf)
2462 {
2463         /* save constructed buffers for next time */
2464         if ((char *)buf >= (char *)kmem_dump_start &&
2465             (char *)buf < (char *)kmem_dump_end) {
2466                 KMEM_DUMPCTL(cp, buf)->kdc_next = cp->cache_dumpfreelist;
2467                 cp->cache_dumpfreelist = buf;
2468                 KDI_LOG(cp, kdl_frees);
2469                 return (0);
2470         }
2471 
2472         /* count all non-dump buf frees */
2473         KDI_LOG(cp, kdl_free_nondump);
2474 
2475         /* just drop buffers that were allocated before dump started */
2476         if (kmem_dump_curr < kmem_dump_end)
2477                 return (0);
2478 
2479         /* fall back to normal free if reserved area is used up */
2480         return (1);
2481 }
2482 
2483 /*
2484  * Allocate a constructed object from cache cp.
2485  */
2486 void *
2487 kmem_cache_alloc(kmem_cache_t *cp, int kmflag)
2488 {
2489         kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2490         kmem_magazine_t *fmp;
2491         void *buf;
2492 
2493         mutex_enter(&ccp->cc_lock);
2494         for (;;) {
2495                 /*
2496                  * If there's an object available in the current CPU's
2497                  * loaded magazine, just take it and return.
2498                  */
2499                 if (ccp->cc_rounds > 0) {
2500                         buf = ccp->cc_loaded->mag_round[--ccp->cc_rounds];
2501                         ccp->cc_alloc++;
2502                         mutex_exit(&ccp->cc_lock);
2503                         if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPUNSAFE)) {
2504                                 if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2505                                         ASSERT(!(ccp->cc_flags &
2506                                             KMF_DUMPDIVERT));
2507                                         KDI_LOG(cp, kdl_unsafe);
2508                                 }
2509                                 if ((ccp->cc_flags & KMF_BUFTAG) &&
2510                                     kmem_cache_alloc_debug(cp, buf, kmflag, 0,
2511                                     caller()) != 0) {
2512                                         if (kmflag & KM_NOSLEEP)
2513                                                 return (NULL);
2514                                         mutex_enter(&ccp->cc_lock);
2515                                         continue;
2516                                 }
2517                         }
2518                         return (buf);
2519                 }
2520 
2521                 /*
2522                  * The loaded magazine is empty.  If the previously loaded
2523                  * magazine was full, exchange them and try again.
2524                  */
2525                 if (ccp->cc_prounds > 0) {
2526                         kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2527                         continue;
2528                 }
2529 
2530                 /*
2531                  * Return an alternate buffer at dump time to preserve
2532                  * the heap.
2533                  */
2534                 if (ccp->cc_flags & (KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2535                         if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2536                                 ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2537                                 /* log it so that we can warn about it */
2538                                 KDI_LOG(cp, kdl_unsafe);
2539                         } else {
2540                                 if ((buf = kmem_cache_alloc_dump(cp, kmflag)) !=
2541                                     NULL) {
2542                                         mutex_exit(&ccp->cc_lock);
2543                                         return (buf);
2544                                 }
2545                                 break;          /* fall back to slab layer */
2546                         }
2547                 }
2548 
2549                 /*
2550                  * If the magazine layer is disabled, break out now.
2551                  */
2552                 if (ccp->cc_magsize == 0)
2553                         break;
2554 
2555                 /*
2556                  * Try to get a full magazine from the depot.
2557                  */
2558                 fmp = kmem_depot_alloc(cp, &cp->cache_full);
2559                 if (fmp != NULL) {
2560                         if (ccp->cc_ploaded != NULL)
2561                                 kmem_depot_free(cp, &cp->cache_empty,
2562                                     ccp->cc_ploaded);
2563                         kmem_cpu_reload(ccp, fmp, ccp->cc_magsize);
2564                         continue;
2565                 }
2566 
2567                 /*
2568                  * There are no full magazines in the depot,
2569                  * so fall through to the slab layer.
2570                  */
2571                 break;
2572         }
2573         mutex_exit(&ccp->cc_lock);
2574 
2575         /*
2576          * We couldn't allocate a constructed object from the magazine layer,
2577          * so get a raw buffer from the slab layer and apply its constructor.
2578          */
2579         buf = kmem_slab_alloc(cp, kmflag);
2580 
2581         if (buf == NULL)
2582                 return (NULL);
2583 
2584         if (cp->cache_flags & KMF_BUFTAG) {
2585                 /*
2586                  * Make kmem_cache_alloc_debug() apply the constructor for us.
2587                  */
2588                 int rc = kmem_cache_alloc_debug(cp, buf, kmflag, 1, caller());
2589                 if (rc != 0) {
2590                         if (kmflag & KM_NOSLEEP)
2591                                 return (NULL);
2592                         /*
2593                          * kmem_cache_alloc_debug() detected corruption
2594                          * but didn't panic (kmem_panic <= 0). We should not be
2595                          * here because the constructor failed (indicated by a
2596                          * return code of 1). Try again.
2597                          */
2598                         ASSERT(rc == -1);
2599                         return (kmem_cache_alloc(cp, kmflag));
2600                 }
2601                 return (buf);
2602         }
2603 
2604         if (cp->cache_constructor != NULL &&
2605             cp->cache_constructor(buf, cp->cache_private, kmflag) != 0) {
2606                 atomic_inc_64(&cp->cache_alloc_fail);
2607                 kmem_slab_free(cp, buf);
2608                 return (NULL);
2609         }
2610 
2611         return (buf);
2612 }
2613 
2614 /*
2615  * The freed argument tells whether or not kmem_cache_free_debug() has already
2616  * been called so that we can avoid the duplicate free error. For example, a
2617  * buffer on a magazine has already been freed by the client but is still
2618  * constructed.
2619  */
2620 static void
2621 kmem_slab_free_constructed(kmem_cache_t *cp, void *buf, boolean_t freed)
2622 {
2623         if (!freed && (cp->cache_flags & KMF_BUFTAG))
2624                 if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2625                         return;
2626 
2627         /*
2628          * Note that if KMF_DEADBEEF is in effect and KMF_LITE is not,
2629          * kmem_cache_free_debug() will have already applied the destructor.
2630          */
2631         if ((cp->cache_flags & (KMF_DEADBEEF | KMF_LITE)) != KMF_DEADBEEF &&
2632             cp->cache_destructor != NULL) {
2633                 if (cp->cache_flags & KMF_DEADBEEF) {    /* KMF_LITE implied */
2634                         kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2635                         *(uint64_t *)buf = btp->bt_redzone;
2636                         cp->cache_destructor(buf, cp->cache_private);
2637                         *(uint64_t *)buf = KMEM_FREE_PATTERN;
2638                 } else {
2639                         cp->cache_destructor(buf, cp->cache_private);
2640                 }
2641         }
2642 
2643         kmem_slab_free(cp, buf);
2644 }
2645 
2646 /*
2647  * Used when there's no room to free a buffer to the per-CPU cache.
2648  * Drops and re-acquires &ccp->cc_lock, and returns non-zero if the
2649  * caller should try freeing to the per-CPU cache again.
2650  * Note that we don't directly install the magazine in the cpu cache,
2651  * since its state may have changed wildly while the lock was dropped.
2652  */
2653 static int
2654 kmem_cpucache_magazine_alloc(kmem_cpu_cache_t *ccp, kmem_cache_t *cp)
2655 {
2656         kmem_magazine_t *emp;
2657         kmem_magtype_t *mtp;
2658 
2659         ASSERT(MUTEX_HELD(&ccp->cc_lock));
2660         ASSERT(((uint_t)ccp->cc_rounds == ccp->cc_magsize ||
2661             ((uint_t)ccp->cc_rounds == -1)) &&
2662             ((uint_t)ccp->cc_prounds == ccp->cc_magsize ||
2663             ((uint_t)ccp->cc_prounds == -1)));
2664 
2665         emp = kmem_depot_alloc(cp, &cp->cache_empty);
2666         if (emp != NULL) {
2667                 if (ccp->cc_ploaded != NULL)
2668                         kmem_depot_free(cp, &cp->cache_full,
2669                             ccp->cc_ploaded);
2670                 kmem_cpu_reload(ccp, emp, 0);
2671                 return (1);
2672         }
2673         /*
2674          * There are no empty magazines in the depot,
2675          * so try to allocate a new one.  We must drop all locks
2676          * across kmem_cache_alloc() because lower layers may
2677          * attempt to allocate from this cache.
2678          */
2679         mtp = cp->cache_magtype;
2680         mutex_exit(&ccp->cc_lock);
2681         emp = kmem_cache_alloc(mtp->mt_cache, KM_NOSLEEP);
2682         mutex_enter(&ccp->cc_lock);
2683 
2684         if (emp != NULL) {
2685                 /*
2686                  * We successfully allocated an empty magazine.
2687                  * However, we had to drop ccp->cc_lock to do it,
2688                  * so the cache's magazine size may have changed.
2689                  * If so, free the magazine and try again.
2690                  */
2691                 if (ccp->cc_magsize != mtp->mt_magsize) {
2692                         mutex_exit(&ccp->cc_lock);
2693                         kmem_cache_free(mtp->mt_cache, emp);
2694                         mutex_enter(&ccp->cc_lock);
2695                         return (1);
2696                 }
2697 
2698                 /*
2699                  * We got a magazine of the right size.  Add it to
2700                  * the depot and try the whole dance again.
2701                  */
2702                 kmem_depot_free(cp, &cp->cache_empty, emp);
2703                 return (1);
2704         }
2705 
2706         /*
2707          * We couldn't allocate an empty magazine,
2708          * so fall through to the slab layer.
2709          */
2710         return (0);
2711 }
2712 
2713 /*
2714  * Free a constructed object to cache cp.
2715  */
2716 void
2717 kmem_cache_free(kmem_cache_t *cp, void *buf)
2718 {
2719         kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2720 
2721         /*
2722          * The client must not free either of the buffers passed to the move
2723          * callback function.
2724          */
2725         ASSERT(cp->cache_defrag == NULL ||
2726             cp->cache_defrag->kmd_thread != curthread ||
2727             (buf != cp->cache_defrag->kmd_from_buf &&
2728             buf != cp->cache_defrag->kmd_to_buf));
2729 
2730         if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2731                 if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2732                         ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2733                         /* log it so that we can warn about it */
2734                         KDI_LOG(cp, kdl_unsafe);
2735                 } else if (KMEM_DUMPCC(ccp) && !kmem_cache_free_dump(cp, buf)) {
2736                         return;
2737                 }
2738                 if (ccp->cc_flags & KMF_BUFTAG) {
2739                         if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2740                                 return;
2741                 }
2742         }
2743 
2744         mutex_enter(&ccp->cc_lock);
2745         /*
2746          * Any changes to this logic should be reflected in kmem_slab_prefill()
2747          */
2748         for (;;) {
2749                 /*
2750                  * If there's a slot available in the current CPU's
2751                  * loaded magazine, just put the object there and return.
2752                  */
2753                 if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2754                         ccp->cc_loaded->mag_round[ccp->cc_rounds++] = buf;
2755                         ccp->cc_free++;
2756                         mutex_exit(&ccp->cc_lock);
2757                         return;
2758                 }
2759 
2760                 /*
2761                  * The loaded magazine is full.  If the previously loaded
2762                  * magazine was empty, exchange them and try again.
2763                  */
2764                 if (ccp->cc_prounds == 0) {
2765                         kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2766                         continue;
2767                 }
2768 
2769                 /*
2770                  * If the magazine layer is disabled, break out now.
2771                  */
2772                 if (ccp->cc_magsize == 0)
2773                         break;
2774 
2775                 if (!kmem_cpucache_magazine_alloc(ccp, cp)) {
2776                         /*
2777                          * We couldn't free our constructed object to the
2778                          * magazine layer, so apply its destructor and free it
2779                          * to the slab layer.
2780                          */
2781                         break;
2782                 }
2783         }
2784         mutex_exit(&ccp->cc_lock);
2785         kmem_slab_free_constructed(cp, buf, B_TRUE);
2786 }
2787 
2788 static void
2789 kmem_slab_prefill(kmem_cache_t *cp, kmem_slab_t *sp)
2790 {
2791         kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2792         int cache_flags = cp->cache_flags;
2793 
2794         kmem_bufctl_t *next, *head;
2795         size_t nbufs;
2796 
2797         /*
2798          * Completely allocate the newly created slab and put the pre-allocated
2799          * buffers in magazines. Any of the buffers that cannot be put in
2800          * magazines must be returned to the slab.
2801          */
2802         ASSERT(MUTEX_HELD(&cp->cache_lock));
2803         ASSERT((cache_flags & (KMF_PREFILL|KMF_BUFTAG)) == KMF_PREFILL);
2804         ASSERT(cp->cache_constructor == NULL);
2805         ASSERT(sp->slab_cache == cp);
2806         ASSERT(sp->slab_refcnt == 1);
2807         ASSERT(sp->slab_head != NULL && sp->slab_chunks > sp->slab_refcnt);
2808         ASSERT(avl_find(&cp->cache_partial_slabs, sp, NULL) == NULL);
2809 
2810         head = sp->slab_head;
2811         nbufs = (sp->slab_chunks - sp->slab_refcnt);
2812         sp->slab_head = NULL;
2813         sp->slab_refcnt += nbufs;
2814         cp->cache_bufslab -= nbufs;
2815         cp->cache_slab_alloc += nbufs;
2816         list_insert_head(&cp->cache_complete_slabs, sp);
2817         cp->cache_complete_slab_count++;
2818         mutex_exit(&cp->cache_lock);
2819         mutex_enter(&ccp->cc_lock);
2820 
2821         while (head != NULL) {
2822                 void *buf = KMEM_BUF(cp, head);
2823                 /*
2824                  * If there's a slot available in the current CPU's
2825                  * loaded magazine, just put the object there and
2826                  * continue.
2827                  */
2828                 if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2829                         ccp->cc_loaded->mag_round[ccp->cc_rounds++] =
2830                             buf;
2831                         ccp->cc_free++;
2832                         nbufs--;
2833                         head = head->bc_next;
2834                         continue;
2835                 }
2836 
2837                 /*
2838                  * The loaded magazine is full.  If the previously
2839                  * loaded magazine was empty, exchange them and try
2840                  * again.
2841                  */
2842                 if (ccp->cc_prounds == 0) {
2843                         kmem_cpu_reload(ccp, ccp->cc_ploaded,
2844                             ccp->cc_prounds);
2845                         continue;
2846                 }
2847 
2848                 /*
2849                  * If the magazine layer is disabled, break out now.
2850                  */
2851 
2852                 if (ccp->cc_magsize == 0) {
2853                         break;
2854                 }
2855 
2856                 if (!kmem_cpucache_magazine_alloc(ccp, cp))
2857                         break;
2858         }
2859         mutex_exit(&ccp->cc_lock);
2860         if (nbufs != 0) {
2861                 ASSERT(head != NULL);
2862 
2863                 /*
2864                  * If there was a failure, return remaining objects to
2865                  * the slab
2866                  */
2867                 while (head != NULL) {
2868                         ASSERT(nbufs != 0);
2869                         next = head->bc_next;
2870                         head->bc_next = NULL;
2871                         kmem_slab_free(cp, KMEM_BUF(cp, head));
2872                         head = next;
2873                         nbufs--;
2874                 }
2875         }
2876         ASSERT(head == NULL);
2877         ASSERT(nbufs == 0);
2878         mutex_enter(&cp->cache_lock);
2879 }
2880 
2881 void *
2882 kmem_zalloc(size_t size, int kmflag)
2883 {
2884         size_t index;
2885         void *buf;
2886 
2887         if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2888                 kmem_cache_t *cp = kmem_alloc_table[index];
2889                 buf = kmem_cache_alloc(cp, kmflag);
2890                 if (buf != NULL) {
2891                         if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2892                                 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2893                                 ((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2894                                 ((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2895 
2896                                 if (cp->cache_flags & KMF_LITE) {
2897                                         KMEM_BUFTAG_LITE_ENTER(btp,
2898                                             kmem_lite_count, caller());
2899                                 }
2900                         }
2901                         bzero(buf, size);
2902                 }
2903         } else {
2904                 buf = kmem_alloc(size, kmflag);
2905                 if (buf != NULL)
2906                         bzero(buf, size);
2907         }
2908         return (buf);
2909 }
2910 
2911 void *
2912 kmem_alloc(size_t size, int kmflag)
2913 {
2914         size_t index;
2915         kmem_cache_t *cp;
2916         void *buf;
2917 
2918         if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2919                 cp = kmem_alloc_table[index];
2920                 /* fall through to kmem_cache_alloc() */
2921 
2922         } else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2923             kmem_big_alloc_table_max) {
2924                 cp = kmem_big_alloc_table[index];
2925                 /* fall through to kmem_cache_alloc() */
2926 
2927         } else {
2928                 if (size == 0)
2929                         return (NULL);
2930 
2931                 buf = vmem_alloc(kmem_oversize_arena, size,
2932                     kmflag & KM_VMFLAGS);
2933                 if (buf == NULL)
2934                         kmem_log_event(kmem_failure_log, NULL, NULL,
2935                             (void *)size);
2936                 else if (KMEM_DUMP(kmem_slab_cache)) {
2937                         /* stats for dump intercept */
2938                         kmem_dump_oversize_allocs++;
2939                         if (size > kmem_dump_oversize_max)
2940                                 kmem_dump_oversize_max = size;
2941                 }
2942                 return (buf);
2943         }
2944 
2945         buf = kmem_cache_alloc(cp, kmflag);
2946         if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp) && buf != NULL) {
2947                 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2948                 ((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2949                 ((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2950 
2951                 if (cp->cache_flags & KMF_LITE) {
2952                         KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller());
2953                 }
2954         }
2955         return (buf);
2956 }
2957 
2958 void
2959 kmem_free(void *buf, size_t size)
2960 {
2961         size_t index;
2962         kmem_cache_t *cp;
2963 
2964         if ((index = (size - 1) >> KMEM_ALIGN_SHIFT) < KMEM_ALLOC_TABLE_MAX) {
2965                 cp = kmem_alloc_table[index];
2966                 /* fall through to kmem_cache_free() */
2967 
2968         } else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2969             kmem_big_alloc_table_max) {
2970                 cp = kmem_big_alloc_table[index];
2971                 /* fall through to kmem_cache_free() */
2972 
2973         } else {
2974                 EQUIV(buf == NULL, size == 0);
2975                 if (buf == NULL && size == 0)
2976                         return;
2977                 vmem_free(kmem_oversize_arena, buf, size);
2978                 return;
2979         }
2980 
2981         if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2982                 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2983                 uint32_t *ip = (uint32_t *)btp;
2984                 if (ip[1] != KMEM_SIZE_ENCODE(size)) {
2985                         if (*(uint64_t *)buf == KMEM_FREE_PATTERN) {
2986                                 kmem_error(KMERR_DUPFREE, cp, buf);
2987                                 return;
2988                         }
2989                         if (KMEM_SIZE_VALID(ip[1])) {
2990                                 ip[0] = KMEM_SIZE_ENCODE(size);
2991                                 kmem_error(KMERR_BADSIZE, cp, buf);
2992                         } else {
2993                                 kmem_error(KMERR_REDZONE, cp, buf);
2994                         }
2995                         return;
2996                 }
2997                 if (((uint8_t *)buf)[size] != KMEM_REDZONE_BYTE) {
2998                         kmem_error(KMERR_REDZONE, cp, buf);
2999                         return;
3000                 }
3001                 btp->bt_redzone = KMEM_REDZONE_PATTERN;
3002                 if (cp->cache_flags & KMF_LITE) {
3003                         KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count,
3004                             caller());
3005                 }
3006         }
3007         kmem_cache_free(cp, buf);
3008 }
3009 
3010 void *
3011 kmem_firewall_va_alloc(vmem_t *vmp, size_t size, int vmflag)
3012 {
3013         size_t realsize = size + vmp->vm_quantum;
3014         void *addr;
3015 
3016         /*
3017          * Annoying edge case: if 'size' is just shy of ULONG_MAX, adding
3018          * vm_quantum will cause integer wraparound.  Check for this, and
3019          * blow off the firewall page in this case.  Note that such a
3020          * giant allocation (the entire kernel address space) can never
3021          * be satisfied, so it will either fail immediately (VM_NOSLEEP)
3022          * or sleep forever (VM_SLEEP).  Thus, there is no need for a
3023          * corresponding check in kmem_firewall_va_free().
3024          */
3025         if (realsize < size)
3026                 realsize = size;
3027 
3028         /*
3029          * While boot still owns resource management, make sure that this
3030          * redzone virtual address allocation is properly accounted for in
3031          * OBPs "virtual-memory" "available" lists because we're
3032          * effectively claiming them for a red zone.  If we don't do this,
3033          * the available lists become too fragmented and too large for the
3034          * current boot/kernel memory list interface.
3035          */
3036         addr = vmem_alloc(vmp, realsize, vmflag | VM_NEXTFIT);
3037 
3038         if (addr != NULL && kvseg.s_base == NULL && realsize != size)
3039                 (void) boot_virt_alloc((char *)addr + size, vmp->vm_quantum);
3040 
3041         return (addr);
3042 }
3043 
3044 void
3045 kmem_firewall_va_free(vmem_t *vmp, void *addr, size_t size)
3046 {
3047         ASSERT((kvseg.s_base == NULL ?
3048             va_to_pfn((char *)addr + size) :
3049             hat_getpfnum(kas.a_hat, (caddr_t)addr + size)) == PFN_INVALID);
3050 
3051         vmem_free(vmp, addr, size + vmp->vm_quantum);
3052 }
3053 
3054 /*
3055  * Try to allocate at least `size' bytes of memory without sleeping or
3056  * panicking. Return actual allocated size in `asize'. If allocation failed,
3057  * try final allocation with sleep or panic allowed.
3058  */
3059 void *
3060 kmem_alloc_tryhard(size_t size, size_t *asize, int kmflag)
3061 {
3062         void *p;
3063 
3064         *asize = P2ROUNDUP(size, KMEM_ALIGN);
3065         do {
3066                 p = kmem_alloc(*asize, (kmflag | KM_NOSLEEP) & ~KM_PANIC);
3067                 if (p != NULL)
3068                         return (p);
3069                 *asize += KMEM_ALIGN;
3070         } while (*asize <= PAGESIZE);
3071 
3072         *asize = P2ROUNDUP(size, KMEM_ALIGN);
3073         return (kmem_alloc(*asize, kmflag));
3074 }
3075 
3076 /*
3077  * Reclaim all unused memory from a cache.
3078  */
3079 static void
3080 kmem_cache_reap(kmem_cache_t *cp)
3081 {
3082         ASSERT(taskq_member(kmem_taskq, curthread));
3083         cp->cache_reap++;
3084 
3085         /*
3086          * Ask the cache's owner to free some memory if possible.
3087          * The idea is to handle things like the inode cache, which
3088          * typically sits on a bunch of memory that it doesn't truly
3089          * *need*.  Reclaim policy is entirely up to the owner; this
3090          * callback is just an advisory plea for help.
3091          */
3092         if (cp->cache_reclaim != NULL) {
3093                 long delta;
3094 
3095                 /*
3096                  * Reclaimed memory should be reapable (not included in the
3097                  * depot's working set).
3098                  */
3099                 delta = cp->cache_full.ml_total;
3100                 cp->cache_reclaim(cp->cache_private);
3101                 delta = cp->cache_full.ml_total - delta;
3102                 if (delta > 0) {
3103                         mutex_enter(&cp->cache_depot_lock);
3104                         cp->cache_full.ml_reaplimit += delta;
3105                         cp->cache_full.ml_min += delta;
3106                         mutex_exit(&cp->cache_depot_lock);
3107                 }
3108         }
3109 
3110         kmem_depot_ws_reap(cp);
3111 
3112         if (cp->cache_defrag != NULL && !kmem_move_noreap) {
3113                 kmem_cache_defrag(cp);
3114         }
3115 }
3116 
3117 static void
3118 kmem_reap_timeout(void *flag_arg)
3119 {
3120         uint32_t *flag = (uint32_t *)flag_arg;
3121 
3122         ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3123         *flag = 0;
3124 }
3125 
3126 static void
3127 kmem_reap_done(void *flag)
3128 {
3129         if (!callout_init_done) {
3130                 /* can't schedule a timeout at this point */
3131                 kmem_reap_timeout(flag);
3132         } else {
3133                 (void) timeout(kmem_reap_timeout, flag, kmem_reap_interval);
3134         }
3135 }
3136 
3137 static void
3138 kmem_reap_start(void *flag)
3139 {
3140         ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3141 
3142         if (flag == &kmem_reaping) {
3143                 kmem_cache_applyall(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3144                 /*
3145                  * if we have segkp under heap, reap segkp cache.
3146                  */
3147                 if (segkp_fromheap)
3148                         segkp_cache_free();
3149         }
3150         else
3151                 kmem_cache_applyall_id(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3152 
3153         /*
3154          * We use taskq_dispatch() to schedule a timeout to clear
3155          * the flag so that kmem_reap() becomes self-throttling:
3156          * we won't reap again until the current reap completes *and*
3157          * at least kmem_reap_interval ticks have elapsed.
3158          */
3159         if (!taskq_dispatch(kmem_taskq, kmem_reap_done, flag, TQ_NOSLEEP))
3160                 kmem_reap_done(flag);
3161 }
3162 
3163 static void
3164 kmem_reap_common(void *flag_arg)
3165 {
3166         uint32_t *flag = (uint32_t *)flag_arg;
3167 
3168         if (MUTEX_HELD(&kmem_cache_lock) || kmem_taskq == NULL ||
3169             atomic_cas_32(flag, 0, 1) != 0)
3170                 return;
3171 
3172         /*
3173          * It may not be kosher to do memory allocation when a reap is called
3174          * is called (for example, if vmem_populate() is in the call chain).
3175          * So we start the reap going with a TQ_NOALLOC dispatch.  If the
3176          * dispatch fails, we reset the flag, and the next reap will try again.
3177          */
3178         if (!taskq_dispatch(kmem_taskq, kmem_reap_start, flag, TQ_NOALLOC))
3179                 *flag = 0;
3180 }
3181 
3182 /*
3183  * Reclaim all unused memory from all caches.  Called from the VM system
3184  * when memory gets tight.
3185  */
3186 void
3187 kmem_reap(void)
3188 {
3189         kmem_reap_common(&kmem_reaping);
3190 }
3191 
3192 /*
3193  * Reclaim all unused memory from identifier arenas, called when a vmem
3194  * arena not back by memory is exhausted.  Since reaping memory-backed caches
3195  * cannot help with identifier exhaustion, we avoid both a large amount of
3196  * work and unwanted side-effects from reclaim callbacks.
3197  */
3198 void
3199 kmem_reap_idspace(void)
3200 {
3201         kmem_reap_common(&kmem_reaping_idspace);
3202 }
3203 
3204 /*
3205  * Purge all magazines from a cache and set its magazine limit to zero.
3206  * All calls are serialized by the kmem_taskq lock, except for the final
3207  * call from kmem_cache_destroy().
3208  */
3209 static void
3210 kmem_cache_magazine_purge(kmem_cache_t *cp)
3211 {
3212         kmem_cpu_cache_t *ccp;
3213         kmem_magazine_t *mp, *pmp;
3214         int rounds, prounds, cpu_seqid;
3215 
3216         ASSERT(!list_link_active(&cp->cache_link) ||
3217             taskq_member(kmem_taskq, curthread));
3218         ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
3219 
3220         for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3221                 ccp = &cp->cache_cpu[cpu_seqid];
3222 
3223                 mutex_enter(&ccp->cc_lock);
3224                 mp = ccp->cc_loaded;
3225                 pmp = ccp->cc_ploaded;
3226                 rounds = ccp->cc_rounds;
3227                 prounds = ccp->cc_prounds;
3228                 ccp->cc_loaded = NULL;
3229                 ccp->cc_ploaded = NULL;
3230                 ccp->cc_rounds = -1;
3231                 ccp->cc_prounds = -1;
3232                 ccp->cc_magsize = 0;
3233                 mutex_exit(&ccp->cc_lock);
3234 
3235                 if (mp)
3236                         kmem_magazine_destroy(cp, mp, rounds);
3237                 if (pmp)
3238                         kmem_magazine_destroy(cp, pmp, prounds);
3239         }
3240 
3241         /*
3242          * Updating the working set statistics twice in a row has the
3243          * effect of setting the working set size to zero, so everything
3244          * is eligible for reaping.
3245          */
3246         kmem_depot_ws_update(cp);
3247         kmem_depot_ws_update(cp);
3248 
3249         kmem_depot_ws_reap(cp);
3250 }
3251 
3252 /*
3253  * Enable per-cpu magazines on a cache.
3254  */
3255 static void
3256 kmem_cache_magazine_enable(kmem_cache_t *cp)
3257 {
3258         int cpu_seqid;
3259 
3260         if (cp->cache_flags & KMF_NOMAGAZINE)
3261                 return;
3262 
3263         for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3264                 kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3265                 mutex_enter(&ccp->cc_lock);
3266                 ccp->cc_magsize = cp->cache_magtype->mt_magsize;
3267                 mutex_exit(&ccp->cc_lock);
3268         }
3269 
3270 }
3271 
3272 /*
3273  * Reap (almost) everything right now.  See kmem_cache_magazine_purge()
3274  * for explanation of the back-to-back kmem_depot_ws_update() calls.
3275  */
3276 void
3277 kmem_cache_reap_now(kmem_cache_t *cp)
3278 {
3279         ASSERT(list_link_active(&cp->cache_link));
3280 
3281         kmem_depot_ws_update(cp);
3282         kmem_depot_ws_update(cp);
3283 
3284         (void) taskq_dispatch(kmem_taskq,
3285             (task_func_t *)kmem_depot_ws_reap, cp, TQ_SLEEP);
3286         taskq_wait(kmem_taskq);
3287 }
3288 
3289 /*
3290  * Recompute a cache's magazine size.  The trade-off is that larger magazines
3291  * provide a higher transfer rate with the depot, while smaller magazines
3292  * reduce memory consumption.  Magazine resizing is an expensive operation;
3293  * it should not be done frequently.
3294  *
3295  * Changes to the magazine size are serialized by the kmem_taskq lock.
3296  *
3297  * Note: at present this only grows the magazine size.  It might be useful
3298  * to allow shrinkage too.
3299  */
3300 static void
3301 kmem_cache_magazine_resize(kmem_cache_t *cp)
3302 {
3303         kmem_magtype_t *mtp = cp->cache_magtype;
3304 
3305         ASSERT(taskq_member(kmem_taskq, curthread));
3306 
3307         if (cp->cache_chunksize < mtp->mt_maxbuf) {
3308                 kmem_cache_magazine_purge(cp);
3309                 mutex_enter(&cp->cache_depot_lock);
3310                 cp->cache_magtype = ++mtp;
3311                 cp->cache_depot_contention_prev =
3312                     cp->cache_depot_contention + INT_MAX;
3313                 mutex_exit(&cp->cache_depot_lock);
3314                 kmem_cache_magazine_enable(cp);
3315         }
3316 }
3317 
3318 /*
3319  * Rescale a cache's hash table, so that the table size is roughly the
3320  * cache size.  We want the average lookup time to be extremely small.
3321  */
3322 static void
3323 kmem_hash_rescale(kmem_cache_t *cp)
3324 {
3325         kmem_bufctl_t **old_table, **new_table, *bcp;
3326         size_t old_size, new_size, h;
3327 
3328         ASSERT(taskq_member(kmem_taskq, curthread));
3329 
3330         new_size = MAX(KMEM_HASH_INITIAL,
3331             1 << (highbit(3 * cp->cache_buftotal + 4) - 2));
3332         old_size = cp->cache_hash_mask + 1;
3333 
3334         if ((old_size >> 1) <= new_size && new_size <= (old_size << 1))
3335                 return;
3336 
3337         new_table = vmem_alloc(kmem_hash_arena, new_size * sizeof (void *),
3338             VM_NOSLEEP);
3339         if (new_table == NULL)
3340                 return;
3341         bzero(new_table, new_size * sizeof (void *));
3342 
3343         mutex_enter(&cp->cache_lock);
3344 
3345         old_size = cp->cache_hash_mask + 1;
3346         old_table = cp->cache_hash_table;
3347 
3348         cp->cache_hash_mask = new_size - 1;
3349         cp->cache_hash_table = new_table;
3350         cp->cache_rescale++;
3351 
3352         for (h = 0; h < old_size; h++) {
3353                 bcp = old_table[h];
3354                 while (bcp != NULL) {
3355                         void *addr = bcp->bc_addr;
3356                         kmem_bufctl_t *next_bcp = bcp->bc_next;
3357                         kmem_bufctl_t **hash_bucket = KMEM_HASH(cp, addr);
3358                         bcp->bc_next = *hash_bucket;
3359                         *hash_bucket = bcp;
3360                         bcp = next_bcp;
3361                 }
3362         }
3363 
3364         mutex_exit(&cp->cache_lock);
3365 
3366         vmem_free(kmem_hash_arena, old_table, old_size * sizeof (void *));
3367 }
3368 
3369 /*
3370  * Perform periodic maintenance on a cache: hash rescaling, depot working-set
3371  * update, magazine resizing, and slab consolidation.
3372  */
3373 static void
3374 kmem_cache_update(kmem_cache_t *cp)
3375 {
3376         int need_hash_rescale = 0;
3377         int need_magazine_resize = 0;
3378 
3379         ASSERT(MUTEX_HELD(&kmem_cache_lock));
3380 
3381         /*
3382          * If the cache has become much larger or smaller than its hash table,
3383          * fire off a request to rescale the hash table.
3384          */
3385         mutex_enter(&cp->cache_lock);
3386 
3387         if ((cp->cache_flags & KMF_HASH) &&
3388             (cp->cache_buftotal > (cp->cache_hash_mask << 1) ||
3389             (cp->cache_buftotal < (cp->cache_hash_mask >> 1) &&
3390             cp->cache_hash_mask > KMEM_HASH_INITIAL)))
3391                 need_hash_rescale = 1;
3392 
3393         mutex_exit(&cp->cache_lock);
3394 
3395         /*
3396          * Update the depot working set statistics.
3397          */
3398         kmem_depot_ws_update(cp);
3399 
3400         /*
3401          * If there's a lot of contention in the depot,
3402          * increase the magazine size.
3403          */
3404         mutex_enter(&cp->cache_depot_lock);
3405 
3406         if (cp->cache_chunksize < cp->cache_magtype->mt_maxbuf &&
3407             (int)(cp->cache_depot_contention -
3408             cp->cache_depot_contention_prev) > kmem_depot_contention)
3409                 need_magazine_resize = 1;
3410 
3411         cp->cache_depot_contention_prev = cp->cache_depot_contention;
3412 
3413         mutex_exit(&cp->cache_depot_lock);
3414 
3415         if (need_hash_rescale)
3416                 (void) taskq_dispatch(kmem_taskq,
3417                     (task_func_t *)kmem_hash_rescale, cp, TQ_NOSLEEP);
3418 
3419         if (need_magazine_resize)
3420                 (void) taskq_dispatch(kmem_taskq,
3421                     (task_func_t *)kmem_cache_magazine_resize, cp, TQ_NOSLEEP);
3422 
3423         if (cp->cache_defrag != NULL)
3424                 (void) taskq_dispatch(kmem_taskq,
3425                     (task_func_t *)kmem_cache_scan, cp, TQ_NOSLEEP);
3426 }
3427 
3428 static void kmem_update(void *);
3429 
3430 static void
3431 kmem_update_timeout(void *dummy)
3432 {
3433         (void) timeout(kmem_update, dummy, kmem_reap_interval);
3434 }
3435 
3436 static void
3437 kmem_update(void *dummy)
3438 {
3439         kmem_cache_applyall(kmem_cache_update, NULL, TQ_NOSLEEP);
3440 
3441         /*
3442          * We use taskq_dispatch() to reschedule the timeout so that
3443          * kmem_update() becomes self-throttling: it won't schedule
3444          * new tasks until all previous tasks have completed.
3445          */
3446         if (!taskq_dispatch(kmem_taskq, kmem_update_timeout, dummy, TQ_NOSLEEP))
3447                 kmem_update_timeout(NULL);
3448 }
3449 
3450 static int
3451 kmem_cache_kstat_update(kstat_t *ksp, int rw)
3452 {
3453         struct kmem_cache_kstat *kmcp = &kmem_cache_kstat;
3454         kmem_cache_t *cp = ksp->ks_private;
3455         uint64_t cpu_buf_avail;
3456         uint64_t buf_avail = 0;
3457         int cpu_seqid;
3458         long reap;
3459 
3460         ASSERT(MUTEX_HELD(&kmem_cache_kstat_lock));
3461 
3462         if (rw == KSTAT_WRITE)
3463                 return (EACCES);
3464 
3465         mutex_enter(&cp->cache_lock);
3466 
3467         kmcp->kmc_alloc_fail.value.ui64              = cp->cache_alloc_fail;
3468         kmcp->kmc_alloc.value.ui64           = cp->cache_slab_alloc;
3469         kmcp->kmc_free.value.ui64            = cp->cache_slab_free;
3470         kmcp->kmc_slab_alloc.value.ui64              = cp->cache_slab_alloc;
3471         kmcp->kmc_slab_free.value.ui64               = cp->cache_slab_free;
3472 
3473         for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3474                 kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3475 
3476                 mutex_enter(&ccp->cc_lock);
3477 
3478                 cpu_buf_avail = 0;
3479                 if (ccp->cc_rounds > 0)
3480                         cpu_buf_avail += ccp->cc_rounds;
3481                 if (ccp->cc_prounds > 0)
3482                         cpu_buf_avail += ccp->cc_prounds;
3483 
3484                 kmcp->kmc_alloc.value.ui64   += ccp->cc_alloc;
3485                 kmcp->kmc_free.value.ui64    += ccp->cc_free;
3486                 buf_avail                       += cpu_buf_avail;
3487 
3488                 mutex_exit(&ccp->cc_lock);
3489         }
3490 
3491         mutex_enter(&cp->cache_depot_lock);
3492 
3493         kmcp->kmc_depot_alloc.value.ui64     = cp->cache_full.ml_alloc;
3494         kmcp->kmc_depot_free.value.ui64              = cp->cache_empty.ml_alloc;
3495         kmcp->kmc_depot_contention.value.ui64        = cp->cache_depot_contention;
3496         kmcp->kmc_full_magazines.value.ui64  = cp->cache_full.ml_total;
3497         kmcp->kmc_empty_magazines.value.ui64 = cp->cache_empty.ml_total;
3498         kmcp->kmc_magazine_size.value.ui64   =
3499             (cp->cache_flags & KMF_NOMAGAZINE) ?
3500             0 : cp->cache_magtype->mt_magsize;
3501 
3502         kmcp->kmc_alloc.value.ui64           += cp->cache_full.ml_alloc;
3503         kmcp->kmc_free.value.ui64            += cp->cache_empty.ml_alloc;
3504         buf_avail += cp->cache_full.ml_total * cp->cache_magtype->mt_magsize;
3505 
3506         reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
3507         reap = MIN(reap, cp->cache_full.ml_total);
3508 
3509         mutex_exit(&cp->cache_depot_lock);
3510 
3511         kmcp->kmc_buf_size.value.ui64        = cp->cache_bufsize;
3512         kmcp->kmc_align.value.ui64   = cp->cache_align;
3513         kmcp->kmc_chunk_size.value.ui64      = cp->cache_chunksize;
3514         kmcp->kmc_slab_size.value.ui64       = cp->cache_slabsize;
3515         kmcp->kmc_buf_constructed.value.ui64 = buf_avail;
3516         buf_avail += cp->cache_bufslab;
3517         kmcp->kmc_buf_avail.value.ui64       = buf_avail;
3518         kmcp->kmc_buf_inuse.value.ui64       = cp->cache_buftotal - buf_avail;
3519         kmcp->kmc_buf_total.value.ui64       = cp->cache_buftotal;
3520         kmcp->kmc_buf_max.value.ui64 = cp->cache_bufmax;
3521         kmcp->kmc_slab_create.value.ui64     = cp->cache_slab_create;
3522         kmcp->kmc_slab_destroy.value.ui64    = cp->cache_slab_destroy;
3523         kmcp->kmc_hash_size.value.ui64       = (cp->cache_flags & KMF_HASH) ?
3524             cp->cache_hash_mask + 1 : 0;
3525         kmcp->kmc_hash_lookup_depth.value.ui64       = cp->cache_lookup_depth;
3526         kmcp->kmc_hash_rescale.value.ui64    = cp->cache_rescale;
3527         kmcp->kmc_vmem_source.value.ui64     = cp->cache_arena->vm_id;
3528         kmcp->kmc_reap.value.ui64    = cp->cache_reap;
3529 
3530         if (cp->cache_defrag == NULL) {
3531                 kmcp->kmc_move_callbacks.value.ui64  = 0;
3532                 kmcp->kmc_move_yes.value.ui64                = 0;
3533                 kmcp->kmc_move_no.value.ui64         = 0;
3534                 kmcp->kmc_move_later.value.ui64              = 0;
3535                 kmcp->kmc_move_dont_need.value.ui64  = 0;
3536                 kmcp->kmc_move_dont_know.value.ui64  = 0;
3537                 kmcp->kmc_move_hunt_found.value.ui64 = 0;
3538                 kmcp->kmc_move_slabs_freed.value.ui64        = 0;
3539                 kmcp->kmc_defrag.value.ui64          = 0;
3540                 kmcp->kmc_scan.value.ui64            = 0;
3541                 kmcp->kmc_move_reclaimable.value.ui64        = 0;
3542         } else {
3543                 int64_t reclaimable;
3544 
3545                 kmem_defrag_t *kd = cp->cache_defrag;
3546                 kmcp->kmc_move_callbacks.value.ui64  = kd->kmd_callbacks;
3547                 kmcp->kmc_move_yes.value.ui64                = kd->kmd_yes;
3548                 kmcp->kmc_move_no.value.ui64         = kd->kmd_no;
3549                 kmcp->kmc_move_later.value.ui64              = kd->kmd_later;
3550                 kmcp->kmc_move_dont_need.value.ui64  = kd->kmd_dont_need;
3551                 kmcp->kmc_move_dont_know.value.ui64  = kd->kmd_dont_know;
3552                 kmcp->kmc_move_hunt_found.value.ui64 = kd->kmd_hunt_found;
3553                 kmcp->kmc_move_slabs_freed.value.ui64        = kd->kmd_slabs_freed;
3554                 kmcp->kmc_defrag.value.ui64          = kd->kmd_defrags;
3555                 kmcp->kmc_scan.value.ui64            = kd->kmd_scans;
3556 
3557                 reclaimable = cp->cache_bufslab - (cp->cache_maxchunks - 1);
3558                 reclaimable = MAX(reclaimable, 0);
3559                 reclaimable += ((uint64_t)reap * cp->cache_magtype->mt_magsize);
3560                 kmcp->kmc_move_reclaimable.value.ui64        = reclaimable;
3561         }
3562 
3563         mutex_exit(&cp->cache_lock);
3564         return (0);
3565 }
3566 
3567 /*
3568  * Return a named statistic about a particular cache.
3569  * This shouldn't be called very often, so it's currently designed for
3570  * simplicity (leverages existing kstat support) rather than efficiency.
3571  */
3572 uint64_t
3573 kmem_cache_stat(kmem_cache_t *cp, char *name)
3574 {
3575         int i;
3576         kstat_t *ksp = cp->cache_kstat;
3577         kstat_named_t *knp = (kstat_named_t *)&kmem_cache_kstat;
3578         uint64_t value = 0;
3579 
3580         if (ksp != NULL) {
3581                 mutex_enter(&kmem_cache_kstat_lock);
3582                 (void) kmem_cache_kstat_update(ksp, KSTAT_READ);
3583                 for (i = 0; i < ksp->ks_ndata; i++) {
3584                         if (strcmp(knp[i].name, name) == 0) {
3585                                 value = knp[i].value.ui64;
3586                                 break;
3587                         }
3588                 }
3589                 mutex_exit(&kmem_cache_kstat_lock);
3590         }
3591         return (value);
3592 }
3593 
3594 /*
3595  * Return an estimate of currently available kernel heap memory.
3596  * On 32-bit systems, physical memory may exceed virtual memory,
3597  * we just truncate the result at 1GB.
3598  */
3599 size_t
3600 kmem_avail(void)
3601 {
3602         spgcnt_t rmem = availrmem - tune.t_minarmem;
3603         spgcnt_t fmem = freemem - minfree;
3604 
3605         return ((size_t)ptob(MIN(MAX(MIN(rmem, fmem), 0),
3606             1 << (30 - PAGESHIFT))));
3607 }
3608 
3609 /*
3610  * Return the maximum amount of memory that is (in theory) allocatable
3611  * from the heap. This may be used as an estimate only since there
3612  * is no guarentee this space will still be available when an allocation
3613  * request is made, nor that the space may be allocated in one big request
3614  * due to kernel heap fragmentation.
3615  */
3616 size_t
3617 kmem_maxavail(void)
3618 {
3619         spgcnt_t pmem = availrmem - tune.t_minarmem;
3620         spgcnt_t vmem = btop(vmem_size(heap_arena, VMEM_FREE));
3621 
3622         return ((size_t)ptob(MAX(MIN(pmem, vmem), 0)));
3623 }
3624 
3625 /*
3626  * Indicate whether memory-intensive kmem debugging is enabled.
3627  */
3628 int
3629 kmem_debugging(void)
3630 {
3631         return (kmem_flags & (KMF_AUDIT | KMF_REDZONE));
3632 }
3633 
3634 /* binning function, sorts finely at the two extremes */
3635 #define KMEM_PARTIAL_SLAB_WEIGHT(sp, binshift)                          \
3636         ((((sp)->slab_refcnt <= (binshift)) ||                            \
3637             (((sp)->slab_chunks - (sp)->slab_refcnt) <= (binshift)))   \
3638             ? -(sp)->slab_refcnt                                     \
3639             : -((binshift) + ((sp)->slab_refcnt >> (binshift))))
3640 
3641 /*
3642  * Minimizing the number of partial slabs on the freelist minimizes
3643  * fragmentation (the ratio of unused buffers held by the slab layer). There are
3644  * two ways to get a slab off of the freelist: 1) free all the buffers on the
3645  * slab, and 2) allocate all the buffers on the slab. It follows that we want
3646  * the most-used slabs at the front of the list where they have the best chance
3647  * of being completely allocated, and the least-used slabs at a safe distance
3648  * from the front to improve the odds that the few remaining buffers will all be
3649  * freed before another allocation can tie up the slab. For that reason a slab
3650  * with a higher slab_refcnt sorts less than than a slab with a lower
3651  * slab_refcnt.
3652  *
3653  * However, if a slab has at least one buffer that is deemed unfreeable, we
3654  * would rather have that slab at the front of the list regardless of
3655  * slab_refcnt, since even one unfreeable buffer makes the entire slab
3656  * unfreeable. If the client returns KMEM_CBRC_NO in response to a cache_move()
3657  * callback, the slab is marked unfreeable for as long as it remains on the
3658  * freelist.
3659  */
3660 static int
3661 kmem_partial_slab_cmp(const void *p0, const void *p1)
3662 {
3663         const kmem_cache_t *cp;
3664         const kmem_slab_t *s0 = p0;
3665         const kmem_slab_t *s1 = p1;
3666         int w0, w1;
3667         size_t binshift;
3668 
3669         ASSERT(KMEM_SLAB_IS_PARTIAL(s0));
3670         ASSERT(KMEM_SLAB_IS_PARTIAL(s1));
3671         ASSERT(s0->slab_cache == s1->slab_cache);
3672         cp = s1->slab_cache;
3673         ASSERT(MUTEX_HELD(&cp->cache_lock));
3674         binshift = cp->cache_partial_binshift;
3675 
3676         /* weight of first slab */
3677         w0 = KMEM_PARTIAL_SLAB_WEIGHT(s0, binshift);
3678         if (s0->slab_flags & KMEM_SLAB_NOMOVE) {
3679                 w0 -= cp->cache_maxchunks;
3680         }
3681 
3682         /* weight of second slab */
3683         w1 = KMEM_PARTIAL_SLAB_WEIGHT(s1, binshift);
3684         if (s1->slab_flags & KMEM_SLAB_NOMOVE) {
3685                 w1 -= cp->cache_maxchunks;
3686         }
3687 
3688         if (w0 < w1)
3689                 return (-1);
3690         if (w0 > w1)
3691                 return (1);
3692 
3693         /* compare pointer values */
3694         if ((uintptr_t)s0 < (uintptr_t)s1)
3695                 return (-1);
3696         if ((uintptr_t)s0 > (uintptr_t)s1)
3697                 return (1);
3698 
3699         return (0);
3700 }
3701 
3702 /*
3703  * It must be valid to call the destructor (if any) on a newly created object.
3704  * That is, the constructor (if any) must leave the object in a valid state for
3705  * the destructor.
3706  */
3707 kmem_cache_t *
3708 kmem_cache_create(
3709         char *name,             /* descriptive name for this cache */
3710         size_t bufsize,         /* size of the objects it manages */
3711         size_t align,           /* required object alignment */
3712         int (*constructor)(void *, void *, int), /* object constructor */
3713         void (*destructor)(void *, void *),     /* object destructor */
3714         void (*reclaim)(void *), /* memory reclaim callback */
3715         void *private,          /* pass-thru arg for constr/destr/reclaim */
3716         vmem_t *vmp,            /* vmem source for slab allocation */
3717         int cflags)             /* cache creation flags */
3718 {
3719         int cpu_seqid;
3720         size_t chunksize;
3721         kmem_cache_t *cp;
3722         kmem_magtype_t *mtp;
3723         size_t csize = KMEM_CACHE_SIZE(max_ncpus);
3724 
3725 #ifdef  DEBUG
3726         /*
3727          * Cache names should conform to the rules for valid C identifiers
3728          */
3729         if (!strident_valid(name)) {
3730                 cmn_err(CE_CONT,
3731                     "kmem_cache_create: '%s' is an invalid cache name\n"
3732                     "cache names must conform to the rules for "
3733                     "C identifiers\n", name);
3734         }
3735 #endif  /* DEBUG */
3736 
3737         if (vmp == NULL)
3738                 vmp = kmem_default_arena;
3739 
3740         /*
3741          * If this kmem cache has an identifier vmem arena as its source, mark
3742          * it such to allow kmem_reap_idspace().
3743          */
3744         ASSERT(!(cflags & KMC_IDENTIFIER));   /* consumer should not set this */
3745         if (vmp->vm_cflags & VMC_IDENTIFIER)
3746                 cflags |= KMC_IDENTIFIER;
3747 
3748         /*
3749          * Get a kmem_cache structure.  We arrange that cp->cache_cpu[]
3750          * is aligned on a KMEM_CPU_CACHE_SIZE boundary to prevent
3751          * false sharing of per-CPU data.
3752          */
3753         cp = vmem_xalloc(kmem_cache_arena, csize, KMEM_CPU_CACHE_SIZE,
3754             P2NPHASE(csize, KMEM_CPU_CACHE_SIZE), 0, NULL, NULL, VM_SLEEP);
3755         bzero(cp, csize);
3756         list_link_init(&cp->cache_link);
3757 
3758         if (align == 0)
3759                 align = KMEM_ALIGN;
3760 
3761         /*
3762          * If we're not at least KMEM_ALIGN aligned, we can't use free
3763          * memory to hold bufctl information (because we can't safely
3764          * perform word loads and stores on it).
3765          */
3766         if (align < KMEM_ALIGN)
3767                 cflags |= KMC_NOTOUCH;
3768 
3769         if ((align & (align - 1)) != 0 || align > vmp->vm_quantum)
3770                 panic("kmem_cache_create: bad alignment %lu", align);
3771 
3772         mutex_enter(&kmem_flags_lock);
3773         if (kmem_flags & KMF_RANDOMIZE)
3774                 kmem_flags = (((kmem_flags | ~KMF_RANDOM) + 1) & KMF_RANDOM) |
3775                     KMF_RANDOMIZE;
3776         cp->cache_flags = (kmem_flags | cflags) & KMF_DEBUG;
3777         mutex_exit(&kmem_flags_lock);
3778 
3779         /*
3780          * Make sure all the various flags are reasonable.
3781          */
3782         ASSERT(!(cflags & KMC_NOHASH) || !(cflags & KMC_NOTOUCH));
3783 
3784         if (cp->cache_flags & KMF_LITE) {
3785                 if (bufsize >= kmem_lite_minsize &&
3786                     align <= kmem_lite_maxalign &&
3787                     P2PHASE(bufsize, kmem_lite_maxalign) != 0) {
3788                         cp->cache_flags |= KMF_BUFTAG;
3789                         cp->cache_flags &= ~(KMF_AUDIT | KMF_FIREWALL);
3790                 } else {
3791                         cp->cache_flags &= ~KMF_DEBUG;
3792                 }
3793         }
3794 
3795         if (cp->cache_flags & KMF_DEADBEEF)
3796                 cp->cache_flags |= KMF_REDZONE;
3797 
3798         if ((cflags & KMC_QCACHE) && (cp->cache_flags & KMF_AUDIT))
3799                 cp->cache_flags |= KMF_NOMAGAZINE;
3800 
3801         if (cflags & KMC_NODEBUG)
3802                 cp->cache_flags &= ~KMF_DEBUG;
3803 
3804         if (cflags & KMC_NOTOUCH)
3805                 cp->cache_flags &= ~KMF_TOUCH;
3806 
3807         if (cflags & KMC_PREFILL)
3808                 cp->cache_flags |= KMF_PREFILL;
3809 
3810         if (cflags & KMC_NOHASH)
3811                 cp->cache_flags &= ~(KMF_AUDIT | KMF_FIREWALL);
3812 
3813         if (cflags & KMC_NOMAGAZINE)
3814                 cp->cache_flags |= KMF_NOMAGAZINE;
3815 
3816         if ((cp->cache_flags & KMF_AUDIT) && !(cflags & KMC_NOTOUCH))
3817                 cp->cache_flags |= KMF_REDZONE;
3818 
3819         if (!(cp->cache_flags & KMF_AUDIT))
3820                 cp->cache_flags &= ~KMF_CONTENTS;
3821 
3822         if ((cp->cache_flags & KMF_BUFTAG) && bufsize >= kmem_minfirewall &&
3823             !(cp->cache_flags & KMF_LITE) && !(cflags & KMC_NOHASH))
3824                 cp->cache_flags |= KMF_FIREWALL;
3825 
3826         if (vmp != kmem_default_arena || kmem_firewall_arena == NULL)
3827                 cp->cache_flags &= ~KMF_FIREWALL;
3828 
3829         if (cp->cache_flags & KMF_FIREWALL) {
3830                 cp->cache_flags &= ~KMF_BUFTAG;
3831                 cp->cache_flags |= KMF_NOMAGAZINE;
3832                 ASSERT(vmp == kmem_default_arena);
3833                 vmp = kmem_firewall_arena;
3834         }
3835 
3836         /*
3837          * Set cache properties.
3838          */
3839         (void) strncpy(cp->cache_name, name, KMEM_CACHE_NAMELEN);
3840         strident_canon(cp->cache_name, KMEM_CACHE_NAMELEN + 1);
3841         cp->cache_bufsize = bufsize;
3842         cp->cache_align = align;
3843         cp->cache_constructor = constructor;
3844         cp->cache_destructor = destructor;
3845         cp->cache_reclaim = reclaim;
3846         cp->cache_private = private;
3847         cp->cache_arena = vmp;
3848         cp->cache_cflags = cflags;
3849 
3850         /*
3851          * Determine the chunk size.
3852          */
3853         chunksize = bufsize;
3854 
3855         if (align >= KMEM_ALIGN) {
3856                 chunksize = P2ROUNDUP(chunksize, KMEM_ALIGN);
3857                 cp->cache_bufctl = chunksize - KMEM_ALIGN;
3858         }
3859 
3860         if (cp->cache_flags & KMF_BUFTAG) {
3861                 cp->cache_bufctl = chunksize;
3862                 cp->cache_buftag = chunksize;
3863                 if (cp->cache_flags & KMF_LITE)
3864                         chunksize += KMEM_BUFTAG_LITE_SIZE(kmem_lite_count);
3865                 else
3866                         chunksize += sizeof (kmem_buftag_t);
3867         }
3868 
3869         if (cp->cache_flags & KMF_DEADBEEF) {
3870                 cp->cache_verify = MIN(cp->cache_buftag, kmem_maxverify);
3871                 if (cp->cache_flags & KMF_LITE)
3872                         cp->cache_verify = sizeof (uint64_t);
3873         }
3874 
3875         cp->cache_contents = MIN(cp->cache_bufctl, kmem_content_maxsave);
3876 
3877         cp->cache_chunksize = chunksize = P2ROUNDUP(chunksize, align);
3878 
3879         /*
3880          * Now that we know the chunk size, determine the optimal slab size.
3881          */
3882         if (vmp == kmem_firewall_arena) {
3883                 cp->cache_slabsize = P2ROUNDUP(chunksize, vmp->vm_quantum);
3884                 cp->cache_mincolor = cp->cache_slabsize - chunksize;
3885                 cp->cache_maxcolor = cp->cache_mincolor;
3886                 cp->cache_flags |= KMF_HASH;
3887                 ASSERT(!(cp->cache_flags & KMF_BUFTAG));
3888         } else if ((cflags & KMC_NOHASH) || (!(cflags & KMC_NOTOUCH) &&
3889             !(cp->cache_flags & KMF_AUDIT) &&
3890             chunksize < vmp->vm_quantum / KMEM_VOID_FRACTION)) {
3891                 cp->cache_slabsize = vmp->vm_quantum;
3892                 cp->cache_mincolor = 0;
3893                 cp->cache_maxcolor =
3894                     (cp->cache_slabsize - sizeof (kmem_slab_t)) % chunksize;
3895                 ASSERT(chunksize + sizeof (kmem_slab_t) <= cp->cache_slabsize);
3896                 ASSERT(!(cp->cache_flags & KMF_AUDIT));
3897         } else {
3898                 size_t chunks, bestfit, waste, slabsize;
3899                 size_t minwaste = LONG_MAX;
3900 
3901                 for (chunks = 1; chunks <= KMEM_VOID_FRACTION; chunks++) {
3902                         slabsize = P2ROUNDUP(chunksize * chunks,
3903                             vmp->vm_quantum);
3904                         chunks = slabsize / chunksize;
3905                         waste = (slabsize % chunksize) / chunks;
3906                         if (waste < minwaste) {
3907                                 minwaste = waste;
3908                                 bestfit = slabsize;
3909                         }
3910                 }
3911                 if (cflags & KMC_QCACHE)
3912                         bestfit = VMEM_QCACHE_SLABSIZE(vmp->vm_qcache_max);
3913                 cp->cache_slabsize = bestfit;
3914                 cp->cache_mincolor = 0;
3915                 cp->cache_maxcolor = bestfit % chunksize;
3916                 cp->cache_flags |= KMF_HASH;
3917         }
3918 
3919         cp->cache_maxchunks = (cp->cache_slabsize / cp->cache_chunksize);
3920         cp->cache_partial_binshift = highbit(cp->cache_maxchunks / 16) + 1;
3921 
3922         /*
3923          * Disallowing prefill when either the DEBUG or HASH flag is set or when
3924          * there is a constructor avoids some tricky issues with debug setup
3925          * that may be revisited later. We cannot allow prefill in a
3926          * metadata cache because of potential recursion.
3927          */
3928         if (vmp == kmem_msb_arena ||
3929             cp->cache_flags & (KMF_HASH | KMF_BUFTAG) ||
3930             cp->cache_constructor != NULL)
3931                 cp->cache_flags &= ~KMF_PREFILL;
3932 
3933         if (cp->cache_flags & KMF_HASH) {
3934                 ASSERT(!(cflags & KMC_NOHASH));
3935                 cp->cache_bufctl_cache = (cp->cache_flags & KMF_AUDIT) ?
3936                     kmem_bufctl_audit_cache : kmem_bufctl_cache;
3937         }
3938 
3939         if (cp->cache_maxcolor >= vmp->vm_quantum)
3940                 cp->cache_maxcolor = vmp->vm_quantum - 1;
3941 
3942         cp->cache_color = cp->cache_mincolor;
3943 
3944         /*
3945          * Initialize the rest of the slab layer.
3946          */
3947         mutex_init(&cp->cache_lock, NULL, MUTEX_DEFAULT, NULL);
3948 
3949         avl_create(&cp->cache_partial_slabs, kmem_partial_slab_cmp,
3950             sizeof (kmem_slab_t), offsetof(kmem_slab_t, slab_link));
3951         /* LINTED: E_TRUE_LOGICAL_EXPR */
3952         ASSERT(sizeof (list_node_t) <= sizeof (avl_node_t));
3953         /* reuse partial slab AVL linkage for complete slab list linkage */
3954         list_create(&cp->cache_complete_slabs,
3955             sizeof (kmem_slab_t), offsetof(kmem_slab_t, slab_link));
3956 
3957         if (cp->cache_flags & KMF_HASH) {
3958                 cp->cache_hash_table = vmem_alloc(kmem_hash_arena,
3959                     KMEM_HASH_INITIAL * sizeof (void *), VM_SLEEP);
3960                 bzero(cp->cache_hash_table,
3961                     KMEM_HASH_INITIAL * sizeof (void *));
3962                 cp->cache_hash_mask = KMEM_HASH_INITIAL - 1;
3963                 cp->cache_hash_shift = highbit((ulong_t)chunksize) - 1;
3964         }
3965 
3966         /*
3967          * Initialize the depot.
3968          */
3969         mutex_init(&cp->cache_depot_lock, NULL, MUTEX_DEFAULT, NULL);
3970 
3971         for (mtp = kmem_magtype; chunksize <= mtp->mt_minbuf; mtp++)
3972                 continue;
3973 
3974         cp->cache_magtype = mtp;
3975 
3976         /*
3977          * Initialize the CPU layer.
3978          */
3979         for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3980                 kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3981                 mutex_init(&ccp->cc_lock, NULL, MUTEX_DEFAULT, NULL);
3982                 ccp->cc_flags = cp->cache_flags;
3983                 ccp->cc_rounds = -1;
3984                 ccp->cc_prounds = -1;
3985         }
3986 
3987         /*
3988          * Create the cache's kstats.
3989          */
3990         if ((cp->cache_kstat = kstat_create("unix", 0, cp->cache_name,
3991             "kmem_cache", KSTAT_TYPE_NAMED,
3992             sizeof (kmem_cache_kstat) / sizeof (kstat_named_t),
3993             KSTAT_FLAG_VIRTUAL)) != NULL) {
3994                 cp->cache_kstat->ks_data = &kmem_cache_kstat;
3995                 cp->cache_kstat->ks_update = kmem_cache_kstat_update;
3996                 cp->cache_kstat->ks_private = cp;
3997                 cp->cache_kstat->ks_lock = &kmem_cache_kstat_lock;
3998                 kstat_install(cp->cache_kstat);
3999         }
4000 
4001         /*
4002          * Add the cache to the global list.  This makes it visible
4003          * to kmem_update(), so the cache must be ready for business.
4004          */
4005         mutex_enter(&kmem_cache_lock);
4006         list_insert_tail(&kmem_caches, cp);
4007         mutex_exit(&kmem_cache_lock);
4008 
4009         if (kmem_ready)
4010                 kmem_cache_magazine_enable(cp);
4011 
4012         return (cp);
4013 }
4014 
4015 static int
4016 kmem_move_cmp(const void *buf, const void *p)
4017 {
4018         const kmem_move_t *kmm = p;
4019         uintptr_t v1 = (uintptr_t)buf;
4020         uintptr_t v2 = (uintptr_t)kmm->kmm_from_buf;
4021         return (v1 < v2 ? -1 : (v1 > v2 ? 1 : 0));
4022 }
4023 
4024 static void
4025 kmem_reset_reclaim_threshold(kmem_defrag_t *kmd)
4026 {
4027         kmd->kmd_reclaim_numer = 1;
4028 }
4029 
4030 /*
4031  * Initially, when choosing candidate slabs for buffers to move, we want to be
4032  * very selective and take only slabs that are less than
4033  * (1 / KMEM_VOID_FRACTION) allocated. If we have difficulty finding candidate
4034  * slabs, then we raise the allocation ceiling incrementally. The reclaim
4035  * threshold is reset to (1 / KMEM_VOID_FRACTION) as soon as the cache is no
4036  * longer fragmented.
4037  */
4038 static void
4039 kmem_adjust_reclaim_threshold(kmem_defrag_t *kmd, int direction)
4040 {
4041         if (direction > 0) {
4042                 /* make it easier to find a candidate slab */
4043                 if (kmd->kmd_reclaim_numer < (KMEM_VOID_FRACTION - 1)) {
4044                         kmd->kmd_reclaim_numer++;
4045                 }
4046         } else {
4047                 /* be more selective */
4048                 if (kmd->kmd_reclaim_numer > 1) {
4049                         kmd->kmd_reclaim_numer--;
4050                 }
4051         }
4052 }
4053 
4054 void
4055 kmem_cache_set_move(kmem_cache_t *cp,
4056     kmem_cbrc_t (*move)(void *, void *, size_t, void *))
4057 {
4058         kmem_defrag_t *defrag;
4059 
4060         ASSERT(move != NULL);
4061         /*
4062          * The consolidator does not support NOTOUCH caches because kmem cannot
4063          * initialize their slabs with the 0xbaddcafe memory pattern, which sets
4064          * a low order bit usable by clients to distinguish uninitialized memory
4065          * from known objects (see kmem_slab_create).
4066          */
4067         ASSERT(!(cp->cache_cflags & KMC_NOTOUCH));
4068         ASSERT(!(cp->cache_cflags & KMC_IDENTIFIER));
4069 
4070         /*
4071          * We should not be holding anyone's cache lock when calling
4072          * kmem_cache_alloc(), so allocate in all cases before acquiring the
4073          * lock.
4074          */
4075         defrag = kmem_cache_alloc(kmem_defrag_cache, KM_SLEEP);
4076 
4077         mutex_enter(&cp->cache_lock);
4078 
4079         if (KMEM_IS_MOVABLE(cp)) {
4080                 if (cp->cache_move == NULL) {
4081                         ASSERT(cp->cache_slab_alloc == 0);
4082 
4083                         cp->cache_defrag = defrag;
4084                         defrag = NULL; /* nothing to free */
4085                         bzero(cp->cache_defrag, sizeof (kmem_defrag_t));
4086                         avl_create(&cp->cache_defrag->kmd_moves_pending,
4087                             kmem_move_cmp, sizeof (kmem_move_t),
4088                             offsetof(kmem_move_t, kmm_entry));
4089                         /* LINTED: E_TRUE_LOGICAL_EXPR */
4090                         ASSERT(sizeof (list_node_t) <= sizeof (avl_node_t));
4091                         /* reuse the slab's AVL linkage for deadlist linkage */
4092                         list_create(&cp->cache_defrag->kmd_deadlist,
4093                             sizeof (kmem_slab_t),
4094                             offsetof(kmem_slab_t, slab_link));
4095                         kmem_reset_reclaim_threshold(cp->cache_defrag);
4096                 }
4097                 cp->cache_move = move;
4098         }
4099 
4100         mutex_exit(&cp->cache_lock);
4101 
4102         if (defrag != NULL) {
4103                 kmem_cache_free(kmem_defrag_cache, defrag); /* unused */
4104         }
4105 }
4106 
4107 void
4108 kmem_cache_destroy(kmem_cache_t *cp)
4109 {
4110         int cpu_seqid;
4111 
4112         /*
4113          * Remove the cache from the global cache list so that no one else
4114          * can schedule tasks on its behalf, wait for any pending tasks to
4115          * complete, purge the cache, and then destroy it.
4116          */
4117         mutex_enter(&kmem_cache_lock);
4118         list_remove(&kmem_caches, cp);
4119         mutex_exit(&kmem_cache_lock);
4120 
4121         if (kmem_taskq != NULL)
4122                 taskq_wait(kmem_taskq);
4123         if (kmem_move_taskq != NULL)
4124                 taskq_wait(kmem_move_taskq);
4125 
4126         kmem_cache_magazine_purge(cp);
4127 
4128         mutex_enter(&cp->cache_lock);
4129         if (cp->cache_buftotal != 0)
4130                 cmn_err(CE_WARN, "kmem_cache_destroy: '%s' (%p) not empty",
4131                     cp->cache_name, (void *)cp);
4132         if (cp->cache_defrag != NULL) {
4133                 avl_destroy(&cp->cache_defrag->kmd_moves_pending);
4134                 list_destroy(&cp->cache_defrag->kmd_deadlist);
4135                 kmem_cache_free(kmem_defrag_cache, cp->cache_defrag);
4136                 cp->cache_defrag = NULL;
4137         }
4138         /*
4139          * The cache is now dead.  There should be no further activity.  We
4140          * enforce this by setting land mines in the constructor, destructor,
4141          * reclaim, and move routines that induce a kernel text fault if
4142          * invoked.
4143          */
4144         cp->cache_constructor = (int (*)(void *, void *, int))1;
4145         cp->cache_destructor = (void (*)(void *, void *))2;
4146         cp->cache_reclaim = (void (*)(void *))3;
4147         cp->cache_move = (kmem_cbrc_t (*)(void *, void *, size_t, void *))4;
4148         mutex_exit(&cp->cache_lock);
4149 
4150         kstat_delete(cp->cache_kstat);
4151 
4152         if (cp->cache_hash_table != NULL)
4153                 vmem_free(kmem_hash_arena, cp->cache_hash_table,
4154                     (cp->cache_hash_mask + 1) * sizeof (void *));
4155 
4156         for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++)
4157                 mutex_destroy(&cp->cache_cpu[cpu_seqid].cc_lock);
4158 
4159         mutex_destroy(&cp->cache_depot_lock);
4160         mutex_destroy(&cp->cache_lock);
4161 
4162         vmem_free(kmem_cache_arena, cp, KMEM_CACHE_SIZE(max_ncpus));
4163 }
4164 
4165 /*ARGSUSED*/
4166 static int
4167 kmem_cpu_setup(cpu_setup_t what, int id, void *arg)
4168 {
4169         ASSERT(MUTEX_HELD(&cpu_lock));
4170         if (what == CPU_UNCONFIG) {
4171                 kmem_cache_applyall(kmem_cache_magazine_purge,
4172                     kmem_taskq, TQ_SLEEP);
4173                 kmem_cache_applyall(kmem_cache_magazine_enable,
4174                     kmem_taskq, TQ_SLEEP);
4175         }
4176         return (0);
4177 }
4178 
4179 static void
4180 kmem_alloc_caches_create(const int *array, size_t count,
4181     kmem_cache_t **alloc_table, size_t maxbuf, uint_t shift)
4182 {
4183         char name[KMEM_CACHE_NAMELEN + 1];
4184         size_t table_unit = (1 << shift); /* range of one alloc_table entry */
4185         size_t size = table_unit;
4186         int i;
4187 
4188         for (i = 0; i < count; i++) {
4189                 size_t cache_size = array[i];
4190                 size_t align = KMEM_ALIGN;
4191                 kmem_cache_t *cp;
4192 
4193                 /* if the table has an entry for maxbuf, we're done */
4194                 if (size > maxbuf)
4195                         break;
4196 
4197                 /* cache size must be a multiple of the table unit */
4198                 ASSERT(P2PHASE(cache_size, table_unit) == 0);
4199 
4200                 /*
4201                  * If they allocate a multiple of the coherency granularity,
4202                  * they get a coherency-granularity-aligned address.
4203                  */
4204                 if (IS_P2ALIGNED(cache_size, 64))
4205                         align = 64;
4206                 if (IS_P2ALIGNED(cache_size, PAGESIZE))
4207                         align = PAGESIZE;
4208                 (void) snprintf(name, sizeof (name),
4209                     "kmem_alloc_%lu", cache_size);
4210                 cp = kmem_cache_create(name, cache_size, align,
4211                     NULL, NULL, NULL, NULL, NULL, KMC_KMEM_ALLOC);
4212 
4213                 while (size <= cache_size) {
4214                         alloc_table[(size - 1) >> shift] = cp;
4215                         size += table_unit;
4216                 }
4217         }
4218 
4219         ASSERT(size > maxbuf);               /* i.e. maxbuf <= max(cache_size) */
4220 }
4221 
4222 static void
4223 kmem_cache_init(int pass, int use_large_pages)
4224 {
4225         int i;
4226         size_t maxbuf;
4227         kmem_magtype_t *mtp;
4228 
4229         for (i = 0; i < sizeof (kmem_magtype) / sizeof (*mtp); i++) {
4230                 char name[KMEM_CACHE_NAMELEN + 1];
4231 
4232                 mtp = &kmem_magtype[i];
4233                 (void) sprintf(name, "kmem_magazine_%d", mtp->mt_magsize);
4234                 mtp->mt_cache = kmem_cache_create(name,
4235                     (mtp->mt_magsize + 1) * sizeof (void *),
4236                     mtp->mt_align, NULL, NULL, NULL, NULL,
4237                     kmem_msb_arena, KMC_NOHASH);
4238         }
4239 
4240         kmem_slab_cache = kmem_cache_create("kmem_slab_cache",
4241             sizeof (kmem_slab_t), 0, NULL, NULL, NULL, NULL,
4242             kmem_msb_arena, KMC_NOHASH);
4243 
4244         kmem_bufctl_cache = kmem_cache_create("kmem_bufctl_cache",
4245             sizeof (kmem_bufctl_t), 0, NULL, NULL, NULL, NULL,
4246             kmem_msb_arena, KMC_NOHASH);
4247 
4248         kmem_bufctl_audit_cache = kmem_cache_create("kmem_bufctl_audit_cache",
4249             sizeof (kmem_bufctl_audit_t), 0, NULL, NULL, NULL, NULL,
4250             kmem_msb_arena, KMC_NOHASH);
4251 
4252         if (pass == 2) {
4253                 kmem_va_arena = vmem_create("kmem_va",
4254                     NULL, 0, PAGESIZE,
4255                     vmem_alloc, vmem_free, heap_arena,
4256                     8 * PAGESIZE, VM_SLEEP);
4257 
4258                 if (use_large_pages) {
4259                         kmem_default_arena = vmem_xcreate("kmem_default",
4260                             NULL, 0, PAGESIZE,
4261                             segkmem_alloc_lp, segkmem_free_lp, kmem_va_arena,
4262                             0, VMC_DUMPSAFE | VM_SLEEP);
4263                 } else {
4264                         kmem_default_arena = vmem_create("kmem_default",
4265                             NULL, 0, PAGESIZE,
4266                             segkmem_alloc, segkmem_free, kmem_va_arena,
4267                             0, VMC_DUMPSAFE | VM_SLEEP);
4268                 }
4269 
4270                 /* Figure out what our maximum cache size is */
4271                 maxbuf = kmem_max_cached;
4272                 if (maxbuf <= KMEM_MAXBUF) {
4273                         maxbuf = 0;
4274                         kmem_max_cached = KMEM_MAXBUF;
4275                 } else {
4276                         size_t size = 0;
4277                         size_t max =
4278                             sizeof (kmem_big_alloc_sizes) / sizeof (int);
4279                         /*
4280                          * Round maxbuf up to an existing cache size.  If maxbuf
4281                          * is larger than the largest cache, we truncate it to
4282                          * the largest cache's size.
4283                          */
4284                         for (i = 0; i < max; i++) {
4285                                 size = kmem_big_alloc_sizes[i];
4286                                 if (maxbuf <= size)
4287                                         break;
4288                         }
4289                         kmem_max_cached = maxbuf = size;
4290                 }
4291 
4292                 /*
4293                  * The big alloc table may not be completely overwritten, so
4294                  * we clear out any stale cache pointers from the first pass.
4295                  */
4296                 bzero(kmem_big_alloc_table, sizeof (kmem_big_alloc_table));
4297         } else {
4298                 /*
4299                  * During the first pass, the kmem_alloc_* caches
4300                  * are treated as metadata.
4301                  */
4302                 kmem_default_arena = kmem_msb_arena;
4303                 maxbuf = KMEM_BIG_MAXBUF_32BIT;
4304         }
4305 
4306         /*
4307          * Set up the default caches to back kmem_alloc()
4308          */
4309         kmem_alloc_caches_create(
4310             kmem_alloc_sizes, sizeof (kmem_alloc_sizes) / sizeof (int),
4311             kmem_alloc_table, KMEM_MAXBUF, KMEM_ALIGN_SHIFT);
4312 
4313         kmem_alloc_caches_create(
4314             kmem_big_alloc_sizes, sizeof (kmem_big_alloc_sizes) / sizeof (int),
4315             kmem_big_alloc_table, maxbuf, KMEM_BIG_SHIFT);
4316 
4317         kmem_big_alloc_table_max = maxbuf >> KMEM_BIG_SHIFT;
4318 }
4319 
4320 void
4321 kmem_init(void)
4322 {
4323         kmem_cache_t *cp;
4324         int old_kmem_flags = kmem_flags;
4325         int use_large_pages = 0;
4326         size_t maxverify, minfirewall;
4327 
4328         kstat_init();
4329 
4330         /*
4331          * Small-memory systems (< 24 MB) can't handle kmem_flags overhead.
4332          */
4333         if (physmem < btop(24 << 20) && !(old_kmem_flags & KMF_STICKY))
4334                 kmem_flags = 0;
4335 
4336         /*
4337          * Don't do firewalled allocations if the heap is less than 1TB
4338          * (i.e. on a 32-bit kernel)
4339          * The resulting VM_NEXTFIT allocations would create too much
4340          * fragmentation in a small heap.
4341          */
4342 #if defined(_LP64)
4343         maxverify = minfirewall = PAGESIZE / 2;
4344 #else
4345         maxverify = minfirewall = ULONG_MAX;
4346 #endif
4347 
4348         /* LINTED */
4349         ASSERT(sizeof (kmem_cpu_cache_t) == KMEM_CPU_CACHE_SIZE);
4350 
4351         list_create(&kmem_caches, sizeof (kmem_cache_t),
4352             offsetof(kmem_cache_t, cache_link));
4353 
4354         kmem_metadata_arena = vmem_create("kmem_metadata", NULL, 0, PAGESIZE,
4355             vmem_alloc, vmem_free, heap_arena, 8 * PAGESIZE,
4356             VM_SLEEP | VMC_NO_QCACHE);
4357 
4358         kmem_msb_arena = vmem_create("kmem_msb", NULL, 0,
4359             PAGESIZE, segkmem_alloc, segkmem_free, kmem_metadata_arena, 0,
4360             VMC_DUMPSAFE | VM_SLEEP);
4361 
4362         kmem_cache_arena = vmem_create("kmem_cache", NULL, 0, KMEM_ALIGN,
4363             segkmem_alloc, segkmem_free, kmem_metadata_arena, 0, VM_SLEEP);
4364 
4365         kmem_hash_arena = vmem_create("kmem_hash", NULL, 0, KMEM_ALIGN,
4366             segkmem_alloc, segkmem_free, kmem_metadata_arena, 0, VM_SLEEP);
4367 
4368         kmem_log_arena = vmem_create("kmem_log", NULL, 0, KMEM_ALIGN,
4369             segkmem_alloc, segkmem_free, heap_arena, 0, VM_SLEEP);
4370 
4371         kmem_firewall_va_arena = vmem_create("kmem_firewall_va",
4372             NULL, 0, PAGESIZE,
4373             kmem_firewall_va_alloc, kmem_firewall_va_free, heap_arena,
4374             0, VM_SLEEP);
4375 
4376         kmem_firewall_arena = vmem_create("kmem_firewall", NULL, 0, PAGESIZE,
4377             segkmem_alloc, segkmem_free, kmem_firewall_va_arena, 0,
4378             VMC_DUMPSAFE | VM_SLEEP);
4379 
4380         /* temporary oversize arena for mod_read_system_file */
4381         kmem_oversize_arena = vmem_create("kmem_oversize", NULL, 0, PAGESIZE,
4382             segkmem_alloc, segkmem_free, heap_arena, 0, VM_SLEEP);
4383 
4384         kmem_reap_interval = 15 * hz;
4385 
4386         /*
4387          * Read /etc/system.  This is a chicken-and-egg problem because
4388          * kmem_flags may be set in /etc/system, but mod_read_system_file()
4389          * needs to use the allocator.  The simplest solution is to create
4390          * all the standard kmem caches, read /etc/system, destroy all the
4391          * caches we just created, and then create them all again in light
4392          * of the (possibly) new kmem_flags and other kmem tunables.
4393          */
4394         kmem_cache_init(1, 0);
4395 
4396         mod_read_system_file(boothowto & RB_ASKNAME);
4397 
4398         while ((cp = list_tail(&kmem_caches)) != NULL)
4399                 kmem_cache_destroy(cp);
4400 
4401         vmem_destroy(kmem_oversize_arena);
4402 
4403         if (old_kmem_flags & KMF_STICKY)
4404                 kmem_flags = old_kmem_flags;
4405 
4406         if (!(kmem_flags & KMF_AUDIT))
4407                 vmem_seg_size = offsetof(vmem_seg_t, vs_thread);
4408 
4409         if (kmem_maxverify == 0)
4410                 kmem_maxverify = maxverify;
4411 
4412         if (kmem_minfirewall == 0)
4413                 kmem_minfirewall = minfirewall;
4414 
4415         /*
4416          * give segkmem a chance to figure out if we are using large pages
4417          * for the kernel heap
4418          */
4419         use_large_pages = segkmem_lpsetup();
4420 
4421         /*
4422          * To protect against corruption, we keep the actual number of callers
4423          * KMF_LITE records seperate from the tunable.  We arbitrarily clamp
4424          * to 16, since the overhead for small buffers quickly gets out of
4425          * hand.
4426          *
4427          * The real limit would depend on the needs of the largest KMC_NOHASH
4428          * cache.
4429          */
4430         kmem_lite_count = MIN(MAX(0, kmem_lite_pcs), 16);
4431         kmem_lite_pcs = kmem_lite_count;
4432 
4433         /*
4434          * Normally, we firewall oversized allocations when possible, but
4435          * if we are using large pages for kernel memory, and we don't have
4436          * any non-LITE debugging flags set, we want to allocate oversized
4437          * buffers from large pages, and so skip the firewalling.
4438          */
4439         if (use_large_pages &&
4440             ((kmem_flags & KMF_LITE) || !(kmem_flags & KMF_DEBUG))) {
4441                 kmem_oversize_arena = vmem_xcreate("kmem_oversize", NULL, 0,
4442                     PAGESIZE, segkmem_alloc_lp, segkmem_free_lp, heap_arena,
4443                     0, VMC_DUMPSAFE | VM_SLEEP);
4444         } else {
4445                 kmem_oversize_arena = vmem_create("kmem_oversize",
4446                     NULL, 0, PAGESIZE,
4447                     segkmem_alloc, segkmem_free, kmem_minfirewall < ULONG_MAX?
4448                     kmem_firewall_va_arena : heap_arena, 0, VMC_DUMPSAFE |
4449                     VM_SLEEP);
4450         }
4451 
4452         kmem_cache_init(2, use_large_pages);
4453 
4454         if (kmem_flags & (KMF_AUDIT | KMF_RANDOMIZE)) {
4455                 if (kmem_transaction_log_size == 0)
4456                         kmem_transaction_log_size = kmem_maxavail() / 50;
4457                 kmem_transaction_log = kmem_log_init(kmem_transaction_log_size);
4458         }
4459 
4460         if (kmem_flags & (KMF_CONTENTS | KMF_RANDOMIZE)) {
4461                 if (kmem_content_log_size == 0)
4462                         kmem_content_log_size = kmem_maxavail() / 50;
4463                 kmem_content_log = kmem_log_init(kmem_content_log_size);
4464         }
4465 
4466         kmem_failure_log = kmem_log_init(kmem_failure_log_size);
4467 
4468         kmem_slab_log = kmem_log_init(kmem_slab_log_size);
4469 
4470         /*
4471          * Initialize STREAMS message caches so allocb() is available.
4472          * This allows us to initialize the logging framework (cmn_err(9F),
4473          * strlog(9F), etc) so we can start recording messages.
4474          */
4475         streams_msg_init();
4476 
4477         /*
4478          * Initialize the ZSD framework in Zones so modules loaded henceforth
4479          * can register their callbacks.
4480          */
4481         zone_zsd_init();
4482 
4483         log_init();
4484         taskq_init();
4485 
4486         /*
4487          * Warn about invalid or dangerous values of kmem_flags.
4488          * Always warn about unsupported values.
4489          */
4490         if (((kmem_flags & ~(KMF_AUDIT | KMF_DEADBEEF | KMF_REDZONE |
4491             KMF_CONTENTS | KMF_LITE)) != 0) ||
4492             ((kmem_flags & KMF_LITE) && kmem_flags != KMF_LITE))
4493                 cmn_err(CE_WARN, "kmem_flags set to unsupported value 0x%x. "
4494                     "See the Solaris Tunable Parameters Reference Manual.",
4495                     kmem_flags);
4496 
4497 #ifdef DEBUG
4498         if ((kmem_flags & KMF_DEBUG) == 0)
4499                 cmn_err(CE_NOTE, "kmem debugging disabled.");
4500 #else
4501         /*
4502          * For non-debug kernels, the only "normal" flags are 0, KMF_LITE,
4503          * KMF_REDZONE, and KMF_CONTENTS (the last because it is only enabled
4504          * if KMF_AUDIT is set). We should warn the user about the performance
4505          * penalty of KMF_AUDIT or KMF_DEADBEEF if they are set and KMF_LITE
4506          * isn't set (since that disables AUDIT).
4507          */
4508         if (!(kmem_flags & KMF_LITE) &&
4509             (kmem_flags & (KMF_AUDIT | KMF_DEADBEEF)) != 0)
4510                 cmn_err(CE_WARN, "High-overhead kmem debugging features "
4511                     "enabled (kmem_flags = 0x%x).  Performance degradation "
4512                     "and large memory overhead possible. See the Solaris "
4513                     "Tunable Parameters Reference Manual.", kmem_flags);
4514 #endif /* not DEBUG */
4515 
4516         kmem_cache_applyall(kmem_cache_magazine_enable, NULL, TQ_SLEEP);
4517 
4518         kmem_ready = 1;
4519 
4520         /*
4521          * Initialize the platform-specific aligned/DMA memory allocator.
4522          */
4523         ka_init();
4524 
4525         /*
4526          * Initialize 32-bit ID cache.
4527          */
4528         id32_init();
4529 
4530         /*
4531          * Initialize the networking stack so modules loaded can
4532          * register their callbacks.
4533          */
4534         netstack_init();
4535 }
4536 
4537 static void
4538 kmem_move_init(void)
4539 {
4540         kmem_defrag_cache = kmem_cache_create("kmem_defrag_cache",
4541             sizeof (kmem_defrag_t), 0, NULL, NULL, NULL, NULL,
4542             kmem_msb_arena, KMC_NOHASH);
4543         kmem_move_cache = kmem_cache_create("kmem_move_cache",
4544             sizeof (kmem_move_t), 0, NULL, NULL, NULL, NULL,
4545             kmem_msb_arena, KMC_NOHASH);
4546 
4547         /*
4548          * kmem guarantees that move callbacks are sequential and that even
4549          * across multiple caches no two moves ever execute simultaneously.
4550          * Move callbacks are processed on a separate taskq so that client code
4551          * does not interfere with internal maintenance tasks.
4552          */
4553         kmem_move_taskq = taskq_create_instance("kmem_move_taskq", 0, 1,
4554             minclsyspri, 100, INT_MAX, TASKQ_PREPOPULATE);
4555 }
4556 
4557 void
4558 kmem_thread_init(void)
4559 {
4560         kmem_move_init();
4561         kmem_taskq = taskq_create_instance("kmem_taskq", 0, 1, minclsyspri,
4562             300, INT_MAX, TASKQ_PREPOPULATE);
4563 }
4564 
4565 void
4566 kmem_mp_init(void)
4567 {
4568         mutex_enter(&cpu_lock);
4569         register_cpu_setup_func(kmem_cpu_setup, NULL);
4570         mutex_exit(&cpu_lock);
4571 
4572         kmem_update_timeout(NULL);
4573 
4574         taskq_mp_init();
4575 }
4576 
4577 /*
4578  * Return the slab of the allocated buffer, or NULL if the buffer is not
4579  * allocated. This function may be called with a known slab address to determine
4580  * whether or not the buffer is allocated, or with a NULL slab address to obtain
4581  * an allocated buffer's slab.
4582  */
4583 static kmem_slab_t *
4584 kmem_slab_allocated(kmem_cache_t *cp, kmem_slab_t *sp, void *buf)
4585 {
4586         kmem_bufctl_t *bcp, *bufbcp;
4587 
4588         ASSERT(MUTEX_HELD(&cp->cache_lock));
4589         ASSERT(sp == NULL || KMEM_SLAB_MEMBER(sp, buf));
4590 
4591         if (cp->cache_flags & KMF_HASH) {
4592                 for (bcp = *KMEM_HASH(cp, buf);
4593                     (bcp != NULL) && (bcp->bc_addr != buf);
4594                     bcp = bcp->bc_next) {
4595                         continue;
4596                 }
4597                 ASSERT(sp != NULL && bcp != NULL ? sp == bcp->bc_slab : 1);
4598                 return (bcp == NULL ? NULL : bcp->bc_slab);
4599         }
4600 
4601         if (sp == NULL) {
4602                 sp = KMEM_SLAB(cp, buf);
4603         }
4604         bufbcp = KMEM_BUFCTL(cp, buf);
4605         for (bcp = sp->slab_head;
4606             (bcp != NULL) && (bcp != bufbcp);
4607             bcp = bcp->bc_next) {
4608                 continue;
4609         }
4610         return (bcp == NULL ? sp : NULL);
4611 }
4612 
4613 static boolean_t
4614 kmem_slab_is_reclaimable(kmem_cache_t *cp, kmem_slab_t *sp, int flags)
4615 {
4616         long refcnt = sp->slab_refcnt;
4617 
4618         ASSERT(cp->cache_defrag != NULL);
4619 
4620         /*
4621          * For code coverage we want to be able to move an object within the
4622          * same slab (the only partial slab) even if allocating the destination
4623          * buffer resulted in a completely allocated slab.
4624          */
4625         if (flags & KMM_DEBUG) {
4626                 return ((flags & KMM_DESPERATE) ||
4627                     ((sp->slab_flags & KMEM_SLAB_NOMOVE) == 0));
4628         }
4629 
4630         /* If we're desperate, we don't care if the client said NO. */
4631         if (flags & KMM_DESPERATE) {
4632                 return (refcnt < sp->slab_chunks); /* any partial */
4633         }
4634 
4635         if (sp->slab_flags & KMEM_SLAB_NOMOVE) {
4636                 return (B_FALSE);
4637         }
4638 
4639         if ((refcnt == 1) || kmem_move_any_partial) {
4640                 return (refcnt < sp->slab_chunks);
4641         }
4642 
4643         /*
4644          * The reclaim threshold is adjusted at each kmem_cache_scan() so that
4645          * slabs with a progressively higher percentage of used buffers can be
4646          * reclaimed until the cache as a whole is no longer fragmented.
4647          *
4648          *      sp->slab_refcnt   kmd_reclaim_numer
4649          *      --------------- < ------------------
4650          *      sp->slab_chunks   KMEM_VOID_FRACTION
4651          */
4652         return ((refcnt * KMEM_VOID_FRACTION) <
4653             (sp->slab_chunks * cp->cache_defrag->kmd_reclaim_numer));
4654 }
4655 
4656 static void *
4657 kmem_hunt_mag(kmem_cache_t *cp, kmem_magazine_t *m, int n, void *buf,
4658     void *tbuf)
4659 {
4660         int i;          /* magazine round index */
4661 
4662         for (i = 0; i < n; i++) {
4663                 if (buf == m->mag_round[i]) {
4664                         if (cp->cache_flags & KMF_BUFTAG) {
4665                                 (void) kmem_cache_free_debug(cp, tbuf,
4666                                     caller());
4667                         }
4668                         m->mag_round[i] = tbuf;
4669                         return (buf);
4670                 }
4671         }
4672 
4673         return (NULL);
4674 }
4675 
4676 /*
4677  * Hunt the magazine layer for the given buffer. If found, the buffer is
4678  * removed from the magazine layer and returned, otherwise NULL is returned.
4679  * The state of the returned buffer is freed and constructed.
4680  */
4681 static void *
4682 kmem_hunt_mags(kmem_cache_t *cp, void *buf)
4683 {
4684         kmem_cpu_cache_t *ccp;
4685         kmem_magazine_t *m;
4686         int cpu_seqid;
4687         int n;          /* magazine rounds */
4688         void *tbuf;     /* temporary swap buffer */
4689 
4690         ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4691 
4692         /*
4693          * Allocated a buffer to swap with the one we hope to pull out of a
4694          * magazine when found.
4695          */
4696         tbuf = kmem_cache_alloc(cp, KM_NOSLEEP);
4697         if (tbuf == NULL) {
4698                 KMEM_STAT_ADD(kmem_move_stats.kms_hunt_alloc_fail);
4699                 return (NULL);
4700         }
4701         if (tbuf == buf) {
4702                 KMEM_STAT_ADD(kmem_move_stats.kms_hunt_lucky);
4703                 if (cp->cache_flags & KMF_BUFTAG) {
4704                         (void) kmem_cache_free_debug(cp, buf, caller());
4705                 }
4706                 return (buf);
4707         }
4708 
4709         /* Hunt the depot. */
4710         mutex_enter(&cp->cache_depot_lock);
4711         n = cp->cache_magtype->mt_magsize;
4712         for (m = cp->cache_full.ml_list; m != NULL; m = m->mag_next) {
4713                 if (kmem_hunt_mag(cp, m, n, buf, tbuf) != NULL) {
4714                         mutex_exit(&cp->cache_depot_lock);
4715                         return (buf);
4716                 }
4717         }
4718         mutex_exit(&cp->cache_depot_lock);
4719 
4720         /* Hunt the per-CPU magazines. */
4721         for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
4722                 ccp = &cp->cache_cpu[cpu_seqid];
4723 
4724                 mutex_enter(&ccp->cc_lock);
4725                 m = ccp->cc_loaded;
4726                 n = ccp->cc_rounds;
4727                 if (kmem_hunt_mag(cp, m, n, buf, tbuf) != NULL) {
4728                         mutex_exit(&ccp->cc_lock);
4729                         return (buf);
4730                 }
4731                 m = ccp->cc_ploaded;
4732                 n = ccp->cc_prounds;
4733                 if (kmem_hunt_mag(cp, m, n, buf, tbuf) != NULL) {
4734                         mutex_exit(&ccp->cc_lock);
4735                         return (buf);
4736                 }
4737                 mutex_exit(&ccp->cc_lock);
4738         }
4739 
4740         kmem_cache_free(cp, tbuf);
4741         return (NULL);
4742 }
4743 
4744 /*
4745  * May be called from the kmem_move_taskq, from kmem_cache_move_notify_task(),
4746  * or when the buffer is freed.
4747  */
4748 static void
4749 kmem_slab_move_yes(kmem_cache_t *cp, kmem_slab_t *sp, void *from_buf)
4750 {
4751         ASSERT(MUTEX_HELD(&cp->cache_lock));
4752         ASSERT(KMEM_SLAB_MEMBER(sp, from_buf));
4753 
4754         if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4755                 return;
4756         }
4757 
4758         if (sp->slab_flags & KMEM_SLAB_NOMOVE) {
4759                 if (KMEM_SLAB_OFFSET(sp, from_buf) == sp->slab_stuck_offset) {
4760                         avl_remove(&cp->cache_partial_slabs, sp);
4761                         sp->slab_flags &= ~KMEM_SLAB_NOMOVE;
4762                         sp->slab_stuck_offset = (uint32_t)-1;
4763                         avl_add(&cp->cache_partial_slabs, sp);
4764                 }
4765         } else {
4766                 sp->slab_later_count = 0;
4767                 sp->slab_stuck_offset = (uint32_t)-1;
4768         }
4769 }
4770 
4771 static void
4772 kmem_slab_move_no(kmem_cache_t *cp, kmem_slab_t *sp, void *from_buf)
4773 {
4774         ASSERT(taskq_member(kmem_move_taskq, curthread));
4775         ASSERT(MUTEX_HELD(&cp->cache_lock));
4776         ASSERT(KMEM_SLAB_MEMBER(sp, from_buf));
4777 
4778         if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4779                 return;
4780         }
4781 
4782         avl_remove(&cp->cache_partial_slabs, sp);
4783         sp->slab_later_count = 0;
4784         sp->slab_flags |= KMEM_SLAB_NOMOVE;
4785         sp->slab_stuck_offset = KMEM_SLAB_OFFSET(sp, from_buf);
4786         avl_add(&cp->cache_partial_slabs, sp);
4787 }
4788 
4789 static void kmem_move_end(kmem_cache_t *, kmem_move_t *);
4790 
4791 /*
4792  * The move callback takes two buffer addresses, the buffer to be moved, and a
4793  * newly allocated and constructed buffer selected by kmem as the destination.
4794  * It also takes the size of the buffer and an optional user argument specified
4795  * at cache creation time. kmem guarantees that the buffer to be moved has not
4796  * been unmapped by the virtual memory subsystem. Beyond that, it cannot
4797  * guarantee the present whereabouts of the buffer to be moved, so it is up to
4798  * the client to safely determine whether or not it is still using the buffer.
4799  * The client must not free either of the buffers passed to the move callback,
4800  * since kmem wants to free them directly to the slab layer. The client response
4801  * tells kmem which of the two buffers to free:
4802  *
4803  * YES          kmem frees the old buffer (the move was successful)
4804  * NO           kmem frees the new buffer, marks the slab of the old buffer
4805  *              non-reclaimable to avoid bothering the client again
4806  * LATER        kmem frees the new buffer, increments slab_later_count
4807  * DONT_KNOW    kmem frees the new buffer, searches mags for the old buffer
4808  * DONT_NEED    kmem frees both the old buffer and the new buffer
4809  *
4810  * The pending callback argument now being processed contains both of the
4811  * buffers (old and new) passed to the move callback function, the slab of the
4812  * old buffer, and flags related to the move request, such as whether or not the
4813  * system was desperate for memory.
4814  *
4815  * Slabs are not freed while there is a pending callback, but instead are kept
4816  * on a deadlist, which is drained after the last callback completes. This means
4817  * that slabs are safe to access until kmem_move_end(), no matter how many of
4818  * their buffers have been freed. Once slab_refcnt reaches zero, it stays at
4819  * zero for as long as the slab remains on the deadlist and until the slab is
4820  * freed.
4821  */
4822 static void
4823 kmem_move_buffer(kmem_move_t *callback)
4824 {
4825         kmem_cbrc_t response;
4826         kmem_slab_t *sp = callback->kmm_from_slab;
4827         kmem_cache_t *cp = sp->slab_cache;
4828         boolean_t free_on_slab;
4829 
4830         ASSERT(taskq_member(kmem_move_taskq, curthread));
4831         ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4832         ASSERT(KMEM_SLAB_MEMBER(sp, callback->kmm_from_buf));
4833 
4834         /*
4835          * The number of allocated buffers on the slab may have changed since we
4836          * last checked the slab's reclaimability (when the pending move was
4837          * enqueued), or the client may have responded NO when asked to move
4838          * another buffer on the same slab.
4839          */
4840         if (!kmem_slab_is_reclaimable(cp, sp, callback->kmm_flags)) {
4841                 KMEM_STAT_ADD(kmem_move_stats.kms_no_longer_reclaimable);
4842                 KMEM_STAT_COND_ADD((callback->kmm_flags & KMM_NOTIFY),
4843                     kmem_move_stats.kms_notify_no_longer_reclaimable);
4844                 kmem_slab_free(cp, callback->kmm_to_buf);
4845                 kmem_move_end(cp, callback);
4846                 return;
4847         }
4848 
4849         /*
4850          * Hunting magazines is expensive, so we'll wait to do that until the
4851          * client responds KMEM_CBRC_DONT_KNOW. However, checking the slab layer
4852          * is cheap, so we might as well do that here in case we can avoid
4853          * bothering the client.
4854          */
4855         mutex_enter(&cp->cache_lock);
4856         free_on_slab = (kmem_slab_allocated(cp, sp,
4857             callback->kmm_from_buf) == NULL);
4858         mutex_exit(&cp->cache_lock);
4859 
4860         if (free_on_slab) {
4861                 KMEM_STAT_ADD(kmem_move_stats.kms_hunt_found_slab);
4862                 kmem_slab_free(cp, callback->kmm_to_buf);
4863                 kmem_move_end(cp, callback);
4864                 return;
4865         }
4866 
4867         if (cp->cache_flags & KMF_BUFTAG) {
4868                 /*
4869                  * Make kmem_cache_alloc_debug() apply the constructor for us.
4870                  */
4871                 if (kmem_cache_alloc_debug(cp, callback->kmm_to_buf,
4872                     KM_NOSLEEP, 1, caller()) != 0) {
4873                         KMEM_STAT_ADD(kmem_move_stats.kms_alloc_fail);
4874                         kmem_move_end(cp, callback);
4875                         return;
4876                 }
4877         } else if (cp->cache_constructor != NULL &&
4878             cp->cache_constructor(callback->kmm_to_buf, cp->cache_private,
4879             KM_NOSLEEP) != 0) {
4880                 atomic_inc_64(&cp->cache_alloc_fail);
4881                 KMEM_STAT_ADD(kmem_move_stats.kms_constructor_fail);
4882                 kmem_slab_free(cp, callback->kmm_to_buf);
4883                 kmem_move_end(cp, callback);
4884                 return;
4885         }
4886 
4887         KMEM_STAT_ADD(kmem_move_stats.kms_callbacks);
4888         KMEM_STAT_COND_ADD((callback->kmm_flags & KMM_NOTIFY),
4889             kmem_move_stats.kms_notify_callbacks);
4890         cp->cache_defrag->kmd_callbacks++;
4891         cp->cache_defrag->kmd_thread = curthread;
4892         cp->cache_defrag->kmd_from_buf = callback->kmm_from_buf;
4893         cp->cache_defrag->kmd_to_buf = callback->kmm_to_buf;
4894         DTRACE_PROBE2(kmem__move__start, kmem_cache_t *, cp, kmem_move_t *,
4895             callback);
4896 
4897         response = cp->cache_move(callback->kmm_from_buf,
4898             callback->kmm_to_buf, cp->cache_bufsize, cp->cache_private);
4899 
4900         DTRACE_PROBE3(kmem__move__end, kmem_cache_t *, cp, kmem_move_t *,
4901             callback, kmem_cbrc_t, response);
4902         cp->cache_defrag->kmd_thread = NULL;
4903         cp->cache_defrag->kmd_from_buf = NULL;
4904         cp->cache_defrag->kmd_to_buf = NULL;
4905 
4906         if (response == KMEM_CBRC_YES) {
4907                 KMEM_STAT_ADD(kmem_move_stats.kms_yes);
4908                 cp->cache_defrag->kmd_yes++;
4909                 kmem_slab_free_constructed(cp, callback->kmm_from_buf, B_FALSE);
4910                 /* slab safe to access until kmem_move_end() */
4911                 if (sp->slab_refcnt == 0)
4912                         cp->cache_defrag->kmd_slabs_freed++;
4913                 mutex_enter(&cp->cache_lock);
4914                 kmem_slab_move_yes(cp, sp, callback->kmm_from_buf);
4915                 mutex_exit(&cp->cache_lock);
4916                 kmem_move_end(cp, callback);
4917                 return;
4918         }
4919 
4920         switch (response) {
4921         case KMEM_CBRC_NO:
4922                 KMEM_STAT_ADD(kmem_move_stats.kms_no);
4923                 cp->cache_defrag->kmd_no++;
4924                 mutex_enter(&cp->cache_lock);
4925                 kmem_slab_move_no(cp, sp, callback->kmm_from_buf);
4926                 mutex_exit(&cp->cache_lock);
4927                 break;
4928         case KMEM_CBRC_LATER:
4929                 KMEM_STAT_ADD(kmem_move_stats.kms_later);
4930                 cp->cache_defrag->kmd_later++;
4931                 mutex_enter(&cp->cache_lock);
4932                 if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4933                         mutex_exit(&cp->cache_lock);
4934                         break;
4935                 }
4936 
4937                 if (++sp->slab_later_count >= KMEM_DISBELIEF) {
4938                         KMEM_STAT_ADD(kmem_move_stats.kms_disbelief);
4939                         kmem_slab_move_no(cp, sp, callback->kmm_from_buf);
4940                 } else if (!(sp->slab_flags & KMEM_SLAB_NOMOVE)) {
4941                         sp->slab_stuck_offset = KMEM_SLAB_OFFSET(sp,
4942                             callback->kmm_from_buf);
4943                 }
4944                 mutex_exit(&cp->cache_lock);
4945                 break;
4946         case KMEM_CBRC_DONT_NEED:
4947                 KMEM_STAT_ADD(kmem_move_stats.kms_dont_need);
4948                 cp->cache_defrag->kmd_dont_need++;
4949                 kmem_slab_free_constructed(cp, callback->kmm_from_buf, B_FALSE);
4950                 if (sp->slab_refcnt == 0)
4951                         cp->cache_defrag->kmd_slabs_freed++;
4952                 mutex_enter(&cp->cache_lock);
4953                 kmem_slab_move_yes(cp, sp, callback->kmm_from_buf);
4954                 mutex_exit(&cp->cache_lock);
4955                 break;
4956         case KMEM_CBRC_DONT_KNOW:
4957                 KMEM_STAT_ADD(kmem_move_stats.kms_dont_know);
4958                 cp->cache_defrag->kmd_dont_know++;
4959                 if (kmem_hunt_mags(cp, callback->kmm_from_buf) != NULL) {
4960                         KMEM_STAT_ADD(kmem_move_stats.kms_hunt_found_mag);
4961                         cp->cache_defrag->kmd_hunt_found++;
4962                         kmem_slab_free_constructed(cp, callback->kmm_from_buf,
4963                             B_TRUE);
4964                         if (sp->slab_refcnt == 0)
4965                                 cp->cache_defrag->kmd_slabs_freed++;
4966                         mutex_enter(&cp->cache_lock);
4967                         kmem_slab_move_yes(cp, sp, callback->kmm_from_buf);
4968                         mutex_exit(&cp->cache_lock);
4969                 }
4970                 break;
4971         default:
4972                 panic("'%s' (%p) unexpected move callback response %d\n",
4973                     cp->cache_name, (void *)cp, response);
4974         }
4975 
4976         kmem_slab_free_constructed(cp, callback->kmm_to_buf, B_FALSE);
4977         kmem_move_end(cp, callback);
4978 }
4979 
4980 /* Return B_FALSE if there is insufficient memory for the move request. */
4981 static boolean_t
4982 kmem_move_begin(kmem_cache_t *cp, kmem_slab_t *sp, void *buf, int flags)
4983 {
4984         void *to_buf;
4985         avl_index_t index;
4986         kmem_move_t *callback, *pending;
4987         ulong_t n;
4988 
4989         ASSERT(taskq_member(kmem_taskq, curthread));
4990         ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4991         ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
4992 
4993         callback = kmem_cache_alloc(kmem_move_cache, KM_NOSLEEP);
4994         if (callback == NULL) {
4995                 KMEM_STAT_ADD(kmem_move_stats.kms_callback_alloc_fail);
4996                 return (B_FALSE);
4997         }
4998 
4999         callback->kmm_from_slab = sp;
5000         callback->kmm_from_buf = buf;
5001         callback->kmm_flags = flags;
5002 
5003         mutex_enter(&cp->cache_lock);
5004 
5005         n = avl_numnodes(&cp->cache_partial_slabs);
5006         if ((n == 0) || ((n == 1) && !(flags & KMM_DEBUG))) {
5007                 mutex_exit(&cp->cache_lock);
5008                 kmem_cache_free(kmem_move_cache, callback);
5009                 return (B_TRUE); /* there is no need for the move request */
5010         }
5011 
5012         pending = avl_find(&cp->cache_defrag->kmd_moves_pending, buf, &index);
5013         if (pending != NULL) {
5014                 /*
5015                  * If the move is already pending and we're desperate now,
5016                  * update the move flags.
5017                  */
5018                 if (flags & KMM_DESPERATE) {
5019                         pending->kmm_flags |= KMM_DESPERATE;
5020                 }
5021                 mutex_exit(&cp->cache_lock);
5022                 KMEM_STAT_ADD(kmem_move_stats.kms_already_pending);
5023                 kmem_cache_free(kmem_move_cache, callback);
5024                 return (B_TRUE);
5025         }
5026 
5027         to_buf = kmem_slab_alloc_impl(cp, avl_first(&cp->cache_partial_slabs),
5028             B_FALSE);
5029         callback->kmm_to_buf = to_buf;
5030         avl_insert(&cp->cache_defrag->kmd_moves_pending, callback, index);
5031 
5032         mutex_exit(&cp->cache_lock);
5033 
5034         if (!taskq_dispatch(kmem_move_taskq, (task_func_t *)kmem_move_buffer,
5035             callback, TQ_NOSLEEP)) {
5036                 KMEM_STAT_ADD(kmem_move_stats.kms_callback_taskq_fail);
5037                 mutex_enter(&cp->cache_lock);
5038                 avl_remove(&cp->cache_defrag->kmd_moves_pending, callback);
5039                 mutex_exit(&cp->cache_lock);
5040                 kmem_slab_free(cp, to_buf);
5041                 kmem_cache_free(kmem_move_cache, callback);
5042                 return (B_FALSE);
5043         }
5044 
5045         return (B_TRUE);
5046 }
5047 
5048 static void
5049 kmem_move_end(kmem_cache_t *cp, kmem_move_t *callback)
5050 {
5051         avl_index_t index;
5052 
5053         ASSERT(cp->cache_defrag != NULL);
5054         ASSERT(taskq_member(kmem_move_taskq, curthread));
5055         ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
5056 
5057         mutex_enter(&cp->cache_lock);
5058         VERIFY(avl_find(&cp->cache_defrag->kmd_moves_pending,
5059             callback->kmm_from_buf, &index) != NULL);
5060         avl_remove(&cp->cache_defrag->kmd_moves_pending, callback);
5061         if (avl_is_empty(&cp->cache_defrag->kmd_moves_pending)) {
5062                 list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
5063                 kmem_slab_t *sp;
5064 
5065                 /*
5066                  * The last pending move completed. Release all slabs from the
5067                  * front of the dead list except for any slab at the tail that
5068                  * needs to be released from the context of kmem_move_buffers().
5069                  * kmem deferred unmapping the buffers on these slabs in order
5070                  * to guarantee that buffers passed to the move callback have
5071                  * been touched only by kmem or by the client itself.
5072                  */
5073                 while ((sp = list_remove_head(deadlist)) != NULL) {
5074                         if (sp->slab_flags & KMEM_SLAB_MOVE_PENDING) {
5075                                 list_insert_tail(deadlist, sp);
5076                                 break;
5077                         }
5078                         cp->cache_defrag->kmd_deadcount--;
5079                         cp->cache_slab_destroy++;
5080                         mutex_exit(&cp->cache_lock);
5081                         kmem_slab_destroy(cp, sp);
5082                         KMEM_STAT_ADD(kmem_move_stats.kms_dead_slabs_freed);
5083                         mutex_enter(&cp->cache_lock);
5084                 }
5085         }
5086         mutex_exit(&cp->cache_lock);
5087         kmem_cache_free(kmem_move_cache, callback);
5088 }
5089 
5090 /*
5091  * Move buffers from least used slabs first by scanning backwards from the end
5092  * of the partial slab list. Scan at most max_scan candidate slabs and move
5093  * buffers from at most max_slabs slabs (0 for all partial slabs in both cases).
5094  * If desperate to reclaim memory, move buffers from any partial slab, otherwise
5095  * skip slabs with a ratio of allocated buffers at or above the current
5096  * threshold. Return the number of unskipped slabs (at most max_slabs, -1 if the
5097  * scan is aborted) so that the caller can adjust the reclaimability threshold
5098  * depending on how many reclaimable slabs it finds.
5099  *
5100  * kmem_move_buffers() drops and reacquires cache_lock every time it issues a
5101  * move request, since it is not valid for kmem_move_begin() to call
5102  * kmem_cache_alloc() or taskq_dispatch() with cache_lock held.
5103  */
5104 static int
5105 kmem_move_buffers(kmem_cache_t *cp, size_t max_scan, size_t max_slabs,
5106     int flags)
5107 {
5108         kmem_slab_t *sp;
5109         void *buf;
5110         int i, j; /* slab index, buffer index */
5111         int s; /* reclaimable slabs */
5112         int b; /* allocated (movable) buffers on reclaimable slab */
5113         boolean_t success;
5114         int refcnt;
5115         int nomove;
5116 
5117         ASSERT(taskq_member(kmem_taskq, curthread));
5118         ASSERT(MUTEX_HELD(&cp->cache_lock));
5119         ASSERT(kmem_move_cache != NULL);
5120         ASSERT(cp->cache_move != NULL && cp->cache_defrag != NULL);
5121         ASSERT((flags & KMM_DEBUG) ? !avl_is_empty(&cp->cache_partial_slabs) :
5122             avl_numnodes(&cp->cache_partial_slabs) > 1);
5123 
5124         if (kmem_move_blocked) {
5125                 return (0);
5126         }
5127 
5128         if (kmem_move_fulltilt) {
5129                 flags |= KMM_DESPERATE;
5130         }
5131 
5132         if (max_scan == 0 || (flags & KMM_DESPERATE)) {
5133                 /*
5134                  * Scan as many slabs as needed to find the desired number of
5135                  * candidate slabs.
5136                  */
5137                 max_scan = (size_t)-1;
5138         }
5139 
5140         if (max_slabs == 0 || (flags & KMM_DESPERATE)) {
5141                 /* Find as many candidate slabs as possible. */
5142                 max_slabs = (size_t)-1;
5143         }
5144 
5145         sp = avl_last(&cp->cache_partial_slabs);
5146         ASSERT(KMEM_SLAB_IS_PARTIAL(sp));
5147         for (i = 0, s = 0; (i < max_scan) && (s < max_slabs) && (sp != NULL) &&
5148             ((sp != avl_first(&cp->cache_partial_slabs)) ||
5149             (flags & KMM_DEBUG));
5150             sp = AVL_PREV(&cp->cache_partial_slabs, sp), i++) {
5151 
5152                 if (!kmem_slab_is_reclaimable(cp, sp, flags)) {
5153                         continue;
5154                 }
5155                 s++;
5156 
5157                 /* Look for allocated buffers to move. */
5158                 for (j = 0, b = 0, buf = sp->slab_base;
5159                     (j < sp->slab_chunks) && (b < sp->slab_refcnt);
5160                     buf = (((char *)buf) + cp->cache_chunksize), j++) {
5161 
5162                         if (kmem_slab_allocated(cp, sp, buf) == NULL) {
5163                                 continue;
5164                         }
5165 
5166                         b++;
5167 
5168                         /*
5169                          * Prevent the slab from being destroyed while we drop
5170                          * cache_lock and while the pending move is not yet
5171                          * registered. Flag the pending move while
5172                          * kmd_moves_pending may still be empty, since we can't
5173                          * yet rely on a non-zero pending move count to prevent
5174                          * the slab from being destroyed.
5175                          */
5176                         ASSERT(!(sp->slab_flags & KMEM_SLAB_MOVE_PENDING));
5177                         sp->slab_flags |= KMEM_SLAB_MOVE_PENDING;
5178                         /*
5179                          * Recheck refcnt and nomove after reacquiring the lock,
5180                          * since these control the order of partial slabs, and
5181                          * we want to know if we can pick up the scan where we
5182                          * left off.
5183                          */
5184                         refcnt = sp->slab_refcnt;
5185                         nomove = (sp->slab_flags & KMEM_SLAB_NOMOVE);
5186                         mutex_exit(&cp->cache_lock);
5187 
5188                         success = kmem_move_begin(cp, sp, buf, flags);
5189 
5190                         /*
5191                          * Now, before the lock is reacquired, kmem could
5192                          * process all pending move requests and purge the
5193                          * deadlist, so that upon reacquiring the lock, sp has
5194                          * been remapped. Or, the client may free all the
5195                          * objects on the slab while the pending moves are still
5196                          * on the taskq. Therefore, the KMEM_SLAB_MOVE_PENDING
5197                          * flag causes the slab to be put at the end of the
5198                          * deadlist and prevents it from being destroyed, since
5199                          * we plan to destroy it here after reacquiring the
5200                          * lock.
5201                          */
5202                         mutex_enter(&cp->cache_lock);
5203                         ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
5204                         sp->slab_flags &= ~KMEM_SLAB_MOVE_PENDING;
5205 
5206                         if (sp->slab_refcnt == 0) {
5207                                 list_t *deadlist =
5208                                     &cp->cache_defrag->kmd_deadlist;
5209                                 list_remove(deadlist, sp);
5210 
5211                                 if (!avl_is_empty(
5212                                     &cp->cache_defrag->kmd_moves_pending)) {
5213                                         /*
5214                                          * A pending move makes it unsafe to
5215                                          * destroy the slab, because even though
5216                                          * the move is no longer needed, the
5217                                          * context where that is determined
5218                                          * requires the slab to exist.
5219                                          * Fortunately, a pending move also
5220                                          * means we don't need to destroy the
5221                                          * slab here, since it will get
5222                                          * destroyed along with any other slabs
5223                                          * on the deadlist after the last
5224                                          * pending move completes.
5225                                          */
5226                                         list_insert_head(deadlist, sp);
5227                                         KMEM_STAT_ADD(kmem_move_stats.
5228                                             kms_endscan_slab_dead);
5229                                         return (-1);
5230                                 }
5231 
5232                                 /*
5233                                  * Destroy the slab now if it was completely
5234                                  * freed while we dropped cache_lock and there
5235                                  * are no pending moves. Since slab_refcnt
5236                                  * cannot change once it reaches zero, no new
5237                                  * pending moves from that slab are possible.
5238                                  */
5239                                 cp->cache_defrag->kmd_deadcount--;
5240                                 cp->cache_slab_destroy++;
5241                                 mutex_exit(&cp->cache_lock);
5242                                 kmem_slab_destroy(cp, sp);
5243                                 KMEM_STAT_ADD(kmem_move_stats.
5244                                     kms_dead_slabs_freed);
5245                                 KMEM_STAT_ADD(kmem_move_stats.
5246                                     kms_endscan_slab_destroyed);
5247                                 mutex_enter(&cp->cache_lock);
5248                                 /*
5249                                  * Since we can't pick up the scan where we left
5250                                  * off, abort the scan and say nothing about the
5251                                  * number of reclaimable slabs.
5252                                  */
5253                                 return (-1);
5254                         }
5255 
5256                         if (!success) {
5257                                 /*
5258                                  * Abort the scan if there is not enough memory
5259                                  * for the request and say nothing about the
5260                                  * number of reclaimable slabs.
5261                                  */
5262                                 KMEM_STAT_COND_ADD(s < max_slabs,
5263                                     kmem_move_stats.kms_endscan_nomem);
5264                                 return (-1);
5265                         }
5266 
5267                         /*
5268                          * The slab's position changed while the lock was
5269                          * dropped, so we don't know where we are in the
5270                          * sequence any more.
5271                          */
5272                         if (sp->slab_refcnt != refcnt) {
5273                                 /*
5274                                  * If this is a KMM_DEBUG move, the slab_refcnt
5275                                  * may have changed because we allocated a
5276                                  * destination buffer on the same slab. In that
5277                                  * case, we're not interested in counting it.
5278                                  */
5279                                 KMEM_STAT_COND_ADD(!(flags & KMM_DEBUG) &&
5280                                     (s < max_slabs),
5281                                     kmem_move_stats.kms_endscan_refcnt_changed);
5282                                 return (-1);
5283                         }
5284                         if ((sp->slab_flags & KMEM_SLAB_NOMOVE) != nomove) {
5285                                 KMEM_STAT_COND_ADD(s < max_slabs,
5286                                     kmem_move_stats.kms_endscan_nomove_changed);
5287                                 return (-1);
5288                         }
5289 
5290                         /*
5291                          * Generating a move request allocates a destination
5292                          * buffer from the slab layer, bumping the first partial
5293                          * slab if it is completely allocated. If the current
5294                          * slab becomes the first partial slab as a result, we
5295                          * can't continue to scan backwards.
5296                          *
5297                          * If this is a KMM_DEBUG move and we allocated the
5298                          * destination buffer from the last partial slab, then
5299                          * the buffer we're moving is on the same slab and our
5300                          * slab_refcnt has changed, causing us to return before
5301                          * reaching here if there are no partial slabs left.
5302                          */
5303                         ASSERT(!avl_is_empty(&cp->cache_partial_slabs));
5304                         if (sp == avl_first(&cp->cache_partial_slabs)) {
5305                                 /*
5306                                  * We're not interested in a second KMM_DEBUG
5307                                  * move.
5308                                  */
5309                                 goto end_scan;
5310                         }
5311                 }
5312         }
5313 end_scan:
5314 
5315         KMEM_STAT_COND_ADD(!(flags & KMM_DEBUG) &&
5316             (s < max_slabs) &&
5317             (sp == avl_first(&cp->cache_partial_slabs)),
5318             kmem_move_stats.kms_endscan_freelist);
5319 
5320         return (s);
5321 }
5322 
5323 typedef struct kmem_move_notify_args {
5324         kmem_cache_t *kmna_cache;
5325         void *kmna_buf;
5326 } kmem_move_notify_args_t;
5327 
5328 static void
5329 kmem_cache_move_notify_task(void *arg)
5330 {
5331         kmem_move_notify_args_t *args = arg;
5332         kmem_cache_t *cp = args->kmna_cache;
5333         void *buf = args->kmna_buf;
5334         kmem_slab_t *sp;
5335 
5336         ASSERT(taskq_member(kmem_taskq, curthread));
5337         ASSERT(list_link_active(&cp->cache_link));
5338 
5339         kmem_free(args, sizeof (kmem_move_notify_args_t));
5340         mutex_enter(&cp->cache_lock);
5341         sp = kmem_slab_allocated(cp, NULL, buf);
5342 
5343         /* Ignore the notification if the buffer is no longer allocated. */
5344         if (sp == NULL) {
5345                 mutex_exit(&cp->cache_lock);
5346                 return;
5347         }
5348 
5349         /* Ignore the notification if there's no reason to move the buffer. */
5350         if (avl_numnodes(&cp->cache_partial_slabs) > 1) {
5351                 /*
5352                  * So far the notification is not ignored. Ignore the
5353                  * notification if the slab is not marked by an earlier refusal
5354                  * to move a buffer.
5355                  */
5356                 if (!(sp->slab_flags & KMEM_SLAB_NOMOVE) &&
5357                     (sp->slab_later_count == 0)) {
5358                         mutex_exit(&cp->cache_lock);
5359                         return;
5360                 }
5361 
5362                 kmem_slab_move_yes(cp, sp, buf);
5363                 ASSERT(!(sp->slab_flags & KMEM_SLAB_MOVE_PENDING));
5364                 sp->slab_flags |= KMEM_SLAB_MOVE_PENDING;
5365                 mutex_exit(&cp->cache_lock);
5366                 /* see kmem_move_buffers() about dropping the lock */
5367                 (void) kmem_move_begin(cp, sp, buf, KMM_NOTIFY);
5368                 mutex_enter(&cp->cache_lock);
5369                 ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
5370                 sp->slab_flags &= ~KMEM_SLAB_MOVE_PENDING;
5371                 if (sp->slab_refcnt == 0) {
5372                         list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
5373                         list_remove(deadlist, sp);
5374 
5375                         if (!avl_is_empty(
5376                             &cp->cache_defrag->kmd_moves_pending)) {
5377                                 list_insert_head(deadlist, sp);
5378                                 mutex_exit(&cp->cache_lock);
5379                                 KMEM_STAT_ADD(kmem_move_stats.
5380                                     kms_notify_slab_dead);
5381                                 return;
5382                         }
5383 
5384                         cp->cache_defrag->kmd_deadcount--;
5385                         cp->cache_slab_destroy++;
5386                         mutex_exit(&cp->cache_lock);
5387                         kmem_slab_destroy(cp, sp);
5388                         KMEM_STAT_ADD(kmem_move_stats.kms_dead_slabs_freed);
5389                         KMEM_STAT_ADD(kmem_move_stats.
5390                             kms_notify_slab_destroyed);
5391                         return;
5392                 }
5393         } else {
5394                 kmem_slab_move_yes(cp, sp, buf);
5395         }
5396         mutex_exit(&cp->cache_lock);
5397 }
5398 
5399 void
5400 kmem_cache_move_notify(kmem_cache_t *cp, void *buf)
5401 {
5402         kmem_move_notify_args_t *args;
5403 
5404         KMEM_STAT_ADD(kmem_move_stats.kms_notify);
5405         args = kmem_alloc(sizeof (kmem_move_notify_args_t), KM_NOSLEEP);
5406         if (args != NULL) {
5407                 args->kmna_cache = cp;
5408                 args->kmna_buf = buf;
5409                 if (!taskq_dispatch(kmem_taskq,
5410                     (task_func_t *)kmem_cache_move_notify_task, args,
5411                     TQ_NOSLEEP))
5412                         kmem_free(args, sizeof (kmem_move_notify_args_t));
5413         }
5414 }
5415 
5416 static void
5417 kmem_cache_defrag(kmem_cache_t *cp)
5418 {
5419         size_t n;
5420 
5421         ASSERT(cp->cache_defrag != NULL);
5422 
5423         mutex_enter(&cp->cache_lock);
5424         n = avl_numnodes(&cp->cache_partial_slabs);
5425         if (n > 1) {
5426                 /* kmem_move_buffers() drops and reacquires cache_lock */
5427                 KMEM_STAT_ADD(kmem_move_stats.kms_defrags);
5428                 cp->cache_defrag->kmd_defrags++;
5429                 (void) kmem_move_buffers(cp, n, 0, KMM_DESPERATE);
5430         }
5431         mutex_exit(&cp->cache_lock);
5432 }
5433 
5434 /* Is this cache above the fragmentation threshold? */
5435 static boolean_t
5436 kmem_cache_frag_threshold(kmem_cache_t *cp, uint64_t nfree)
5437 {
5438         /*
5439          *      nfree           kmem_frag_numer
5440          * ------------------ > ---------------
5441          * cp->cache_buftotal        kmem_frag_denom
5442          */
5443         return ((nfree * kmem_frag_denom) >
5444             (cp->cache_buftotal * kmem_frag_numer));
5445 }
5446 
5447 static boolean_t
5448 kmem_cache_is_fragmented(kmem_cache_t *cp, boolean_t *doreap)
5449 {
5450         boolean_t fragmented;
5451         uint64_t nfree;
5452 
5453         ASSERT(MUTEX_HELD(&cp->cache_lock));
5454         *doreap = B_FALSE;
5455 
5456         if (kmem_move_fulltilt) {
5457                 if (avl_numnodes(&cp->cache_partial_slabs) > 1) {
5458                         return (B_TRUE);
5459                 }
5460         } else {
5461                 if ((cp->cache_complete_slab_count + avl_numnodes(
5462                     &cp->cache_partial_slabs)) < kmem_frag_minslabs) {
5463                         return (B_FALSE);
5464                 }
5465         }
5466 
5467         nfree = cp->cache_bufslab;
5468         fragmented = ((avl_numnodes(&cp->cache_partial_slabs) > 1) &&
5469             kmem_cache_frag_threshold(cp, nfree));
5470 
5471         /*
5472          * Free buffers in the magazine layer appear allocated from the point of
5473          * view of the slab layer. We want to know if the slab layer would
5474          * appear fragmented if we included free buffers from magazines that
5475          * have fallen out of the working set.
5476          */
5477         if (!fragmented) {
5478                 long reap;
5479 
5480                 mutex_enter(&cp->cache_depot_lock);
5481                 reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
5482                 reap = MIN(reap, cp->cache_full.ml_total);
5483                 mutex_exit(&cp->cache_depot_lock);
5484 
5485                 nfree += ((uint64_t)reap * cp->cache_magtype->mt_magsize);
5486                 if (kmem_cache_frag_threshold(cp, nfree)) {
5487                         *doreap = B_TRUE;
5488                 }
5489         }
5490 
5491         return (fragmented);
5492 }
5493 
5494 /* Called periodically from kmem_taskq */
5495 static void
5496 kmem_cache_scan(kmem_cache_t *cp)
5497 {
5498         boolean_t reap = B_FALSE;
5499         kmem_defrag_t *kmd;
5500 
5501         ASSERT(taskq_member(kmem_taskq, curthread));
5502 
5503         mutex_enter(&cp->cache_lock);
5504 
5505         kmd = cp->cache_defrag;
5506         if (kmd->kmd_consolidate > 0) {
5507                 kmd->kmd_consolidate--;
5508                 mutex_exit(&cp->cache_lock);
5509                 kmem_cache_reap(cp);
5510                 return;
5511         }
5512 
5513         if (kmem_cache_is_fragmented(cp, &reap)) {
5514                 size_t slabs_found;
5515 
5516                 /*
5517                  * Consolidate reclaimable slabs from the end of the partial
5518                  * slab list (scan at most kmem_reclaim_scan_range slabs to find
5519                  * reclaimable slabs). Keep track of how many candidate slabs we
5520                  * looked for and how many we actually found so we can adjust
5521                  * the definition of a candidate slab if we're having trouble
5522                  * finding them.
5523                  *
5524                  * kmem_move_buffers() drops and reacquires cache_lock.
5525                  */
5526                 KMEM_STAT_ADD(kmem_move_stats.kms_scans);
5527                 kmd->kmd_scans++;
5528                 slabs_found = kmem_move_buffers(cp, kmem_reclaim_scan_range,
5529                     kmem_reclaim_max_slabs, 0);
5530                 if (slabs_found >= 0) {
5531                         kmd->kmd_slabs_sought += kmem_reclaim_max_slabs;
5532                         kmd->kmd_slabs_found += slabs_found;
5533                 }
5534 
5535                 if (++kmd->kmd_tries >= kmem_reclaim_scan_range) {
5536                         kmd->kmd_tries = 0;
5537 
5538                         /*
5539                          * If we had difficulty finding candidate slabs in
5540                          * previous scans, adjust the threshold so that
5541                          * candidates are easier to find.
5542                          */
5543                         if (kmd->kmd_slabs_found == kmd->kmd_slabs_sought) {
5544                                 kmem_adjust_reclaim_threshold(kmd, -1);
5545                         } else if ((kmd->kmd_slabs_found * 2) <
5546                             kmd->kmd_slabs_sought) {
5547                                 kmem_adjust_reclaim_threshold(kmd, 1);
5548                         }
5549                         kmd->kmd_slabs_sought = 0;
5550                         kmd->kmd_slabs_found = 0;
5551                 }
5552         } else {
5553                 kmem_reset_reclaim_threshold(cp->cache_defrag);
5554 #ifdef  DEBUG
5555                 if (!avl_is_empty(&cp->cache_partial_slabs)) {
5556                         /*
5557                          * In a debug kernel we want the consolidator to
5558                          * run occasionally even when there is plenty of
5559                          * memory.
5560                          */
5561                         uint16_t debug_rand;
5562 
5563                         (void) random_get_bytes((uint8_t *)&debug_rand, 2);
5564                         if (!kmem_move_noreap &&
5565                             ((debug_rand % kmem_mtb_reap) == 0)) {
5566                                 mutex_exit(&cp->cache_lock);
5567                                 KMEM_STAT_ADD(kmem_move_stats.kms_debug_reaps);
5568                                 kmem_cache_reap(cp);
5569                                 return;
5570                         } else if ((debug_rand % kmem_mtb_move) == 0) {
5571                                 KMEM_STAT_ADD(kmem_move_stats.kms_scans);
5572                                 KMEM_STAT_ADD(kmem_move_stats.kms_debug_scans);
5573                                 kmd->kmd_scans++;
5574                                 (void) kmem_move_buffers(cp,
5575                                     kmem_reclaim_scan_range, 1, KMM_DEBUG);
5576                         }
5577                 }
5578 #endif  /* DEBUG */
5579         }
5580 
5581         mutex_exit(&cp->cache_lock);
5582 
5583         if (reap) {
5584                 KMEM_STAT_ADD(kmem_move_stats.kms_scan_depot_ws_reaps);
5585                 kmem_depot_ws_reap(cp);
5586         }
5587 }