xref: /illumos-gate/usr/src/uts/common/os/kmem.c (revision d7db73d1)
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26 
27 /*
28  * Kernel memory allocator, as described in the following two papers and a
29  * statement about the consolidator:
30  *
31  * Jeff Bonwick,
32  * The Slab Allocator: An Object-Caching Kernel Memory Allocator.
33  * Proceedings of the Summer 1994 Usenix Conference.
34  * Available as /shared/sac/PSARC/1994/028/materials/kmem.pdf.
35  *
36  * Jeff Bonwick and Jonathan Adams,
37  * Magazines and vmem: Extending the Slab Allocator to Many CPUs and
38  * Arbitrary Resources.
39  * Proceedings of the 2001 Usenix Conference.
40  * Available as /shared/sac/PSARC/2000/550/materials/vmem.pdf.
41  *
42  * kmem Slab Consolidator Big Theory Statement:
43  *
44  * 1. Motivation
45  *
46  * As stated in Bonwick94, slabs provide the following advantages over other
47  * allocation structures in terms of memory fragmentation:
48  *
49  *  - Internal fragmentation (per-buffer wasted space) is minimal.
50  *  - Severe external fragmentation (unused buffers on the free list) is
51  *    unlikely.
52  *
53  * Segregating objects by size eliminates one source of external fragmentation,
54  * and according to Bonwick:
55  *
56  *   The other reason that slabs reduce external fragmentation is that all
57  *   objects in a slab are of the same type, so they have the same lifetime
58  *   distribution. The resulting segregation of short-lived and long-lived
59  *   objects at slab granularity reduces the likelihood of an entire page being
60  *   held hostage due to a single long-lived allocation [Barrett93, Hanson90].
61  *
62  * While unlikely, severe external fragmentation remains possible. Clients that
63  * allocate both short- and long-lived objects from the same cache cannot
64  * anticipate the distribution of long-lived objects within the allocator's slab
65  * implementation. Even a small percentage of long-lived objects distributed
66  * randomly across many slabs can lead to a worst case scenario where the client
67  * frees the majority of its objects and the system gets back almost none of the
68  * slabs. Despite the client doing what it reasonably can to help the system
69  * reclaim memory, the allocator cannot shake free enough slabs because of
70  * lonely allocations stubbornly hanging on. Although the allocator is in a
71  * position to diagnose the fragmentation, there is nothing that the allocator
72  * by itself can do about it. It only takes a single allocated object to prevent
73  * an entire slab from being reclaimed, and any object handed out by
74  * kmem_cache_alloc() is by definition in the client's control. Conversely,
75  * although the client is in a position to move a long-lived object, it has no
76  * way of knowing if the object is causing fragmentation, and if so, where to
77  * move it. A solution necessarily requires further cooperation between the
78  * allocator and the client.
79  *
80  * 2. Move Callback
81  *
82  * The kmem slab consolidator therefore adds a move callback to the
83  * allocator/client interface, improving worst-case external fragmentation in
84  * kmem caches that supply a function to move objects from one memory location
85  * to another. In a situation of low memory kmem attempts to consolidate all of
86  * a cache's slabs at once; otherwise it works slowly to bring external
87  * fragmentation within the 1/8 limit guaranteed for internal fragmentation,
88  * thereby helping to avoid a low memory situation in the future.
89  *
90  * The callback has the following signature:
91  *
92  *   kmem_cbrc_t move(void *old, void *new, size_t size, void *user_arg)
93  *
94  * It supplies the kmem client with two addresses: the allocated object that
95  * kmem wants to move and a buffer selected by kmem for the client to use as the
96  * copy destination. The callback is kmem's way of saying "Please get off of
97  * this buffer and use this one instead." kmem knows where it wants to move the
98  * object in order to best reduce fragmentation. All the client needs to know
99  * about the second argument (void *new) is that it is an allocated, constructed
100  * object ready to take the contents of the old object. When the move function
101  * is called, the system is likely to be low on memory, and the new object
102  * spares the client from having to worry about allocating memory for the
103  * requested move. The third argument supplies the size of the object, in case a
104  * single move function handles multiple caches whose objects differ only in
105  * size (such as zio_buf_512, zio_buf_1024, etc). Finally, the same optional
106  * user argument passed to the constructor, destructor, and reclaim functions is
107  * also passed to the move callback.
108  *
109  * 2.1 Setting the Move Callback
110  *
111  * The client sets the move callback after creating the cache and before
112  * allocating from it:
113  *
114  *	object_cache = kmem_cache_create(...);
115  *      kmem_cache_set_move(object_cache, object_move);
116  *
117  * 2.2 Move Callback Return Values
118  *
119  * Only the client knows about its own data and when is a good time to move it.
120  * The client is cooperating with kmem to return unused memory to the system,
121  * and kmem respectfully accepts this help at the client's convenience. When
122  * asked to move an object, the client can respond with any of the following:
123  *
124  *   typedef enum kmem_cbrc {
125  *           KMEM_CBRC_YES,
126  *           KMEM_CBRC_NO,
127  *           KMEM_CBRC_LATER,
128  *           KMEM_CBRC_DONT_NEED,
129  *           KMEM_CBRC_DONT_KNOW
130  *   } kmem_cbrc_t;
131  *
132  * The client must not explicitly kmem_cache_free() either of the objects passed
133  * to the callback, since kmem wants to free them directly to the slab layer
134  * (bypassing the per-CPU magazine layer). The response tells kmem which of the
135  * objects to free:
136  *
137  *       YES: (Did it) The client moved the object, so kmem frees the old one.
138  *        NO: (Never) The client refused, so kmem frees the new object (the
139  *            unused copy destination). kmem also marks the slab of the old
140  *            object so as not to bother the client with further callbacks for
141  *            that object as long as the slab remains on the partial slab list.
142  *            (The system won't be getting the slab back as long as the
143  *            immovable object holds it hostage, so there's no point in moving
144  *            any of its objects.)
145  *     LATER: The client is using the object and cannot move it now, so kmem
146  *            frees the new object (the unused copy destination). kmem still
147  *            attempts to move other objects off the slab, since it expects to
148  *            succeed in clearing the slab in a later callback. The client
149  *            should use LATER instead of NO if the object is likely to become
150  *            movable very soon.
151  * DONT_NEED: The client no longer needs the object, so kmem frees the old along
152  *            with the new object (the unused copy destination). This response
153  *            is the client's opportunity to be a model citizen and give back as
154  *            much as it can.
155  * DONT_KNOW: The client does not know about the object because
156  *            a) the client has just allocated the object and not yet put it
157  *               wherever it expects to find known objects
158  *            b) the client has removed the object from wherever it expects to
159  *               find known objects and is about to free it, or
160  *            c) the client has freed the object.
161  *            In all these cases (a, b, and c) kmem frees the new object (the
162  *            unused copy destination).  In the first case, the object is in
163  *            use and the correct action is that for LATER; in the latter two
164  *            cases, we know that the object is either freed or about to be
165  *            freed, in which case it is either already in a magazine or about
166  *            to be in one.  In these cases, we know that the object will either
167  *            be reallocated and reused, or it will end up in a full magazine
168  *            that will be reaped (thereby liberating the slab).  Because it
169  *            is prohibitively expensive to differentiate these cases, and
170  *            because the defrag code is executed when we're low on memory
171  *            (thereby biasing the system to reclaim full magazines) we treat
172  *            all DONT_KNOW cases as LATER and rely on cache reaping to
173  *            generally clean up full magazines.  While we take the same action
174  *            for these cases, we maintain their semantic distinction:  if
175  *            defragmentation is not occurring, it is useful to know if this
176  *            is due to objects in use (LATER) or objects in an unknown state
177  *            of transition (DONT_KNOW).
178  *
179  * 2.3 Object States
180  *
181  * Neither kmem nor the client can be assumed to know the object's whereabouts
182  * at the time of the callback. An object belonging to a kmem cache may be in
183  * any of the following states:
184  *
185  * 1. Uninitialized on the slab
186  * 2. Allocated from the slab but not constructed (still uninitialized)
187  * 3. Allocated from the slab, constructed, but not yet ready for business
188  *    (not in a valid state for the move callback)
189  * 4. In use (valid and known to the client)
190  * 5. About to be freed (no longer in a valid state for the move callback)
191  * 6. Freed to a magazine (still constructed)
192  * 7. Allocated from a magazine, not yet ready for business (not in a valid
193  *    state for the move callback), and about to return to state #4
194  * 8. Deconstructed on a magazine that is about to be freed
195  * 9. Freed to the slab
196  *
197  * Since the move callback may be called at any time while the object is in any
198  * of the above states (except state #1), the client needs a safe way to
199  * determine whether or not it knows about the object. Specifically, the client
200  * needs to know whether or not the object is in state #4, the only state in
201  * which a move is valid. If the object is in any other state, the client should
202  * immediately return KMEM_CBRC_DONT_KNOW, since it is unsafe to access any of
203  * the object's fields.
204  *
205  * Note that although an object may be in state #4 when kmem initiates the move
206  * request, the object may no longer be in that state by the time kmem actually
207  * calls the move function. Not only does the client free objects
208  * asynchronously, kmem itself puts move requests on a queue where thay are
209  * pending until kmem processes them from another context. Also, objects freed
210  * to a magazine appear allocated from the point of view of the slab layer, so
211  * kmem may even initiate requests for objects in a state other than state #4.
212  *
213  * 2.3.1 Magazine Layer
214  *
215  * An important insight revealed by the states listed above is that the magazine
216  * layer is populated only by kmem_cache_free(). Magazines of constructed
217  * objects are never populated directly from the slab layer (which contains raw,
218  * unconstructed objects). Whenever an allocation request cannot be satisfied
219  * from the magazine layer, the magazines are bypassed and the request is
220  * satisfied from the slab layer (creating a new slab if necessary). kmem calls
221  * the object constructor only when allocating from the slab layer, and only in
222  * response to kmem_cache_alloc() or to prepare the destination buffer passed in
223  * the move callback. kmem does not preconstruct objects in anticipation of
224  * kmem_cache_alloc().
225  *
226  * 2.3.2 Object Constructor and Destructor
227  *
228  * If the client supplies a destructor, it must be valid to call the destructor
229  * on a newly created object (immediately after the constructor).
230  *
231  * 2.4 Recognizing Known Objects
232  *
233  * There is a simple test to determine safely whether or not the client knows
234  * about a given object in the move callback. It relies on the fact that kmem
235  * guarantees that the object of the move callback has only been touched by the
236  * client itself or else by kmem. kmem does this by ensuring that none of the
237  * cache's slabs are freed to the virtual memory (VM) subsystem while a move
238  * callback is pending. When the last object on a slab is freed, if there is a
239  * pending move, kmem puts the slab on a per-cache dead list and defers freeing
240  * slabs on that list until all pending callbacks are completed. That way,
241  * clients can be certain that the object of a move callback is in one of the
242  * states listed above, making it possible to distinguish known objects (in
243  * state #4) using the two low order bits of any pointer member (with the
244  * exception of 'char *' or 'short *' which may not be 4-byte aligned on some
245  * platforms).
246  *
247  * The test works as long as the client always transitions objects from state #4
248  * (known, in use) to state #5 (about to be freed, invalid) by setting the low
249  * order bit of the client-designated pointer member. Since kmem only writes
250  * invalid memory patterns, such as 0xbaddcafe to uninitialized memory and
251  * 0xdeadbeef to freed memory, any scribbling on the object done by kmem is
252  * guaranteed to set at least one of the two low order bits. Therefore, given an
253  * object with a back pointer to a 'container_t *o_container', the client can
254  * test
255  *
256  *      container_t *container = object->o_container;
257  *      if ((uintptr_t)container & 0x3) {
258  *              return (KMEM_CBRC_DONT_KNOW);
259  *      }
260  *
261  * Typically, an object will have a pointer to some structure with a list or
262  * hash where objects from the cache are kept while in use. Assuming that the
263  * client has some way of knowing that the container structure is valid and will
264  * not go away during the move, and assuming that the structure includes a lock
265  * to protect whatever collection is used, then the client would continue as
266  * follows:
267  *
268  *	// Ensure that the container structure does not go away.
269  *      if (container_hold(container) == 0) {
270  *              return (KMEM_CBRC_DONT_KNOW);
271  *      }
272  *      mutex_enter(&container->c_objects_lock);
273  *      if (container != object->o_container) {
274  *              mutex_exit(&container->c_objects_lock);
275  *              container_rele(container);
276  *              return (KMEM_CBRC_DONT_KNOW);
277  *      }
278  *
279  * At this point the client knows that the object cannot be freed as long as
280  * c_objects_lock is held. Note that after acquiring the lock, the client must
281  * recheck the o_container pointer in case the object was removed just before
282  * acquiring the lock.
283  *
284  * When the client is about to free an object, it must first remove that object
285  * from the list, hash, or other structure where it is kept. At that time, to
286  * mark the object so it can be distinguished from the remaining, known objects,
287  * the client sets the designated low order bit:
288  *
289  *      mutex_enter(&container->c_objects_lock);
290  *      object->o_container = (void *)((uintptr_t)object->o_container | 0x1);
291  *      list_remove(&container->c_objects, object);
292  *      mutex_exit(&container->c_objects_lock);
293  *
294  * In the common case, the object is freed to the magazine layer, where it may
295  * be reused on a subsequent allocation without the overhead of calling the
296  * constructor. While in the magazine it appears allocated from the point of
297  * view of the slab layer, making it a candidate for the move callback. Most
298  * objects unrecognized by the client in the move callback fall into this
299  * category and are cheaply distinguished from known objects by the test
300  * described earlier. Because searching magazines is prohibitively expensive
301  * for kmem, clients that do not mark freed objects (and therefore return
302  * KMEM_CBRC_DONT_KNOW for large numbers of objects) may find defragmentation
303  * efficacy reduced.
304  *
305  * Invalidating the designated pointer member before freeing the object marks
306  * the object to be avoided in the callback, and conversely, assigning a valid
307  * value to the designated pointer member after allocating the object makes the
308  * object fair game for the callback:
309  *
310  *      ... allocate object ...
311  *      ... set any initial state not set by the constructor ...
312  *
313  *      mutex_enter(&container->c_objects_lock);
314  *      list_insert_tail(&container->c_objects, object);
315  *      membar_producer();
316  *      object->o_container = container;
317  *      mutex_exit(&container->c_objects_lock);
318  *
319  * Note that everything else must be valid before setting o_container makes the
320  * object fair game for the move callback. The membar_producer() call ensures
321  * that all the object's state is written to memory before setting the pointer
322  * that transitions the object from state #3 or #7 (allocated, constructed, not
323  * yet in use) to state #4 (in use, valid). That's important because the move
324  * function has to check the validity of the pointer before it can safely
325  * acquire the lock protecting the collection where it expects to find known
326  * objects.
327  *
328  * This method of distinguishing known objects observes the usual symmetry:
329  * invalidating the designated pointer is the first thing the client does before
330  * freeing the object, and setting the designated pointer is the last thing the
331  * client does after allocating the object. Of course, the client is not
332  * required to use this method. Fundamentally, how the client recognizes known
333  * objects is completely up to the client, but this method is recommended as an
334  * efficient and safe way to take advantage of the guarantees made by kmem. If
335  * the entire object is arbitrary data without any markable bits from a suitable
336  * pointer member, then the client must find some other method, such as
337  * searching a hash table of known objects.
338  *
339  * 2.5 Preventing Objects From Moving
340  *
341  * Besides a way to distinguish known objects, the other thing that the client
342  * needs is a strategy to ensure that an object will not move while the client
343  * is actively using it. The details of satisfying this requirement tend to be
344  * highly cache-specific. It might seem that the same rules that let a client
345  * remove an object safely should also decide when an object can be moved
346  * safely. However, any object state that makes a removal attempt invalid is
347  * likely to be long-lasting for objects that the client does not expect to
348  * remove. kmem knows nothing about the object state and is equally likely (from
349  * the client's point of view) to request a move for any object in the cache,
350  * whether prepared for removal or not. Even a low percentage of objects stuck
351  * in place by unremovability will defeat the consolidator if the stuck objects
352  * are the same long-lived allocations likely to hold slabs hostage.
353  * Fundamentally, the consolidator is not aimed at common cases. Severe external
354  * fragmentation is a worst case scenario manifested as sparsely allocated
355  * slabs, by definition a low percentage of the cache's objects. When deciding
356  * what makes an object movable, keep in mind the goal of the consolidator: to
357  * bring worst-case external fragmentation within the limits guaranteed for
358  * internal fragmentation. Removability is a poor criterion if it is likely to
359  * exclude more than an insignificant percentage of objects for long periods of
360  * time.
361  *
362  * A tricky general solution exists, and it has the advantage of letting you
363  * move any object at almost any moment, practically eliminating the likelihood
364  * that an object can hold a slab hostage. However, if there is a cache-specific
365  * way to ensure that an object is not actively in use in the vast majority of
366  * cases, a simpler solution that leverages this cache-specific knowledge is
367  * preferred.
368  *
369  * 2.5.1 Cache-Specific Solution
370  *
371  * As an example of a cache-specific solution, the ZFS znode cache takes
372  * advantage of the fact that the vast majority of znodes are only being
373  * referenced from the DNLC. (A typical case might be a few hundred in active
374  * use and a hundred thousand in the DNLC.) In the move callback, after the ZFS
375  * client has established that it recognizes the znode and can access its fields
376  * safely (using the method described earlier), it then tests whether the znode
377  * is referenced by anything other than the DNLC. If so, it assumes that the
378  * znode may be in active use and is unsafe to move, so it drops its locks and
379  * returns KMEM_CBRC_LATER. The advantage of this strategy is that everywhere
380  * else znodes are used, no change is needed to protect against the possibility
381  * of the znode moving. The disadvantage is that it remains possible for an
382  * application to hold a znode slab hostage with an open file descriptor.
383  * However, this case ought to be rare and the consolidator has a way to deal
384  * with it: If the client responds KMEM_CBRC_LATER repeatedly for the same
385  * object, kmem eventually stops believing it and treats the slab as if the
386  * client had responded KMEM_CBRC_NO. Having marked the hostage slab, kmem can
387  * then focus on getting it off of the partial slab list by allocating rather
388  * than freeing all of its objects. (Either way of getting a slab off the
389  * free list reduces fragmentation.)
390  *
391  * 2.5.2 General Solution
392  *
393  * The general solution, on the other hand, requires an explicit hold everywhere
394  * the object is used to prevent it from moving. To keep the client locking
395  * strategy as uncomplicated as possible, kmem guarantees the simplifying
396  * assumption that move callbacks are sequential, even across multiple caches.
397  * Internally, a global queue processed by a single thread supports all caches
398  * implementing the callback function. No matter how many caches supply a move
399  * function, the consolidator never moves more than one object at a time, so the
400  * client does not have to worry about tricky lock ordering involving several
401  * related objects from different kmem caches.
402  *
403  * The general solution implements the explicit hold as a read-write lock, which
404  * allows multiple readers to access an object from the cache simultaneously
405  * while a single writer is excluded from moving it. A single rwlock for the
406  * entire cache would lock out all threads from using any of the cache's objects
407  * even though only a single object is being moved, so to reduce contention,
408  * the client can fan out the single rwlock into an array of rwlocks hashed by
409  * the object address, making it probable that moving one object will not
410  * prevent other threads from using a different object. The rwlock cannot be a
411  * member of the object itself, because the possibility of the object moving
412  * makes it unsafe to access any of the object's fields until the lock is
413  * acquired.
414  *
415  * Assuming a small, fixed number of locks, it's possible that multiple objects
416  * will hash to the same lock. A thread that needs to use multiple objects in
417  * the same function may acquire the same lock multiple times. Since rwlocks are
418  * reentrant for readers, and since there is never more than a single writer at
419  * a time (assuming that the client acquires the lock as a writer only when
420  * moving an object inside the callback), there would seem to be no problem.
421  * However, a client locking multiple objects in the same function must handle
422  * one case of potential deadlock: Assume that thread A needs to prevent both
423  * object 1 and object 2 from moving, and thread B, the callback, meanwhile
424  * tries to move object 3. It's possible, if objects 1, 2, and 3 all hash to the
425  * same lock, that thread A will acquire the lock for object 1 as a reader
426  * before thread B sets the lock's write-wanted bit, preventing thread A from
427  * reacquiring the lock for object 2 as a reader. Unable to make forward
428  * progress, thread A will never release the lock for object 1, resulting in
429  * deadlock.
430  *
431  * There are two ways of avoiding the deadlock just described. The first is to
432  * use rw_tryenter() rather than rw_enter() in the callback function when
433  * attempting to acquire the lock as a writer. If tryenter discovers that the
434  * same object (or another object hashed to the same lock) is already in use, it
435  * aborts the callback and returns KMEM_CBRC_LATER. The second way is to use
436  * rprwlock_t (declared in common/fs/zfs/sys/rprwlock.h) instead of rwlock_t,
437  * since it allows a thread to acquire the lock as a reader in spite of a
438  * waiting writer. This second approach insists on moving the object now, no
439  * matter how many readers the move function must wait for in order to do so,
440  * and could delay the completion of the callback indefinitely (blocking
441  * callbacks to other clients). In practice, a less insistent callback using
442  * rw_tryenter() returns KMEM_CBRC_LATER infrequently enough that there seems
443  * little reason to use anything else.
444  *
445  * Avoiding deadlock is not the only problem that an implementation using an
446  * explicit hold needs to solve. Locking the object in the first place (to
447  * prevent it from moving) remains a problem, since the object could move
448  * between the time you obtain a pointer to the object and the time you acquire
449  * the rwlock hashed to that pointer value. Therefore the client needs to
450  * recheck the value of the pointer after acquiring the lock, drop the lock if
451  * the value has changed, and try again. This requires a level of indirection:
452  * something that points to the object rather than the object itself, that the
453  * client can access safely while attempting to acquire the lock. (The object
454  * itself cannot be referenced safely because it can move at any time.)
455  * The following lock-acquisition function takes whatever is safe to reference
456  * (arg), follows its pointer to the object (using function f), and tries as
457  * often as necessary to acquire the hashed lock and verify that the object
458  * still has not moved:
459  *
460  *      object_t *
461  *      object_hold(object_f f, void *arg)
462  *      {
463  *              object_t *op;
464  *
465  *              op = f(arg);
466  *              if (op == NULL) {
467  *                      return (NULL);
468  *              }
469  *
470  *              rw_enter(OBJECT_RWLOCK(op), RW_READER);
471  *              while (op != f(arg)) {
472  *                      rw_exit(OBJECT_RWLOCK(op));
473  *                      op = f(arg);
474  *                      if (op == NULL) {
475  *                              break;
476  *                      }
477  *                      rw_enter(OBJECT_RWLOCK(op), RW_READER);
478  *              }
479  *
480  *              return (op);
481  *      }
482  *
483  * The OBJECT_RWLOCK macro hashes the object address to obtain the rwlock. The
484  * lock reacquisition loop, while necessary, almost never executes. The function
485  * pointer f (used to obtain the object pointer from arg) has the following type
486  * definition:
487  *
488  *      typedef object_t *(*object_f)(void *arg);
489  *
490  * An object_f implementation is likely to be as simple as accessing a structure
491  * member:
492  *
493  *      object_t *
494  *      s_object(void *arg)
495  *      {
496  *              something_t *sp = arg;
497  *              return (sp->s_object);
498  *      }
499  *
500  * The flexibility of a function pointer allows the path to the object to be
501  * arbitrarily complex and also supports the notion that depending on where you
502  * are using the object, you may need to get it from someplace different.
503  *
504  * The function that releases the explicit hold is simpler because it does not
505  * have to worry about the object moving:
506  *
507  *      void
508  *      object_rele(object_t *op)
509  *      {
510  *              rw_exit(OBJECT_RWLOCK(op));
511  *      }
512  *
513  * The caller is spared these details so that obtaining and releasing an
514  * explicit hold feels like a simple mutex_enter()/mutex_exit() pair. The caller
515  * of object_hold() only needs to know that the returned object pointer is valid
516  * if not NULL and that the object will not move until released.
517  *
518  * Although object_hold() prevents an object from moving, it does not prevent it
519  * from being freed. The caller must take measures before calling object_hold()
520  * (afterwards is too late) to ensure that the held object cannot be freed. The
521  * caller must do so without accessing the unsafe object reference, so any lock
522  * or reference count used to ensure the continued existence of the object must
523  * live outside the object itself.
524  *
525  * Obtaining a new object is a special case where an explicit hold is impossible
526  * for the caller. Any function that returns a newly allocated object (either as
527  * a return value, or as an in-out paramter) must return it already held; after
528  * the caller gets it is too late, since the object cannot be safely accessed
529  * without the level of indirection described earlier. The following
530  * object_alloc() example uses the same code shown earlier to transition a new
531  * object into the state of being recognized (by the client) as a known object.
532  * The function must acquire the hold (rw_enter) before that state transition
533  * makes the object movable:
534  *
535  *      static object_t *
536  *      object_alloc(container_t *container)
537  *      {
538  *              object_t *object = kmem_cache_alloc(object_cache, 0);
539  *              ... set any initial state not set by the constructor ...
540  *              rw_enter(OBJECT_RWLOCK(object), RW_READER);
541  *              mutex_enter(&container->c_objects_lock);
542  *              list_insert_tail(&container->c_objects, object);
543  *              membar_producer();
544  *              object->o_container = container;
545  *              mutex_exit(&container->c_objects_lock);
546  *              return (object);
547  *      }
548  *
549  * Functions that implicitly acquire an object hold (any function that calls
550  * object_alloc() to supply an object for the caller) need to be carefully noted
551  * so that the matching object_rele() is not neglected. Otherwise, leaked holds
552  * prevent all objects hashed to the affected rwlocks from ever being moved.
553  *
554  * The pointer to a held object can be hashed to the holding rwlock even after
555  * the object has been freed. Although it is possible to release the hold
556  * after freeing the object, you may decide to release the hold implicitly in
557  * whatever function frees the object, so as to release the hold as soon as
558  * possible, and for the sake of symmetry with the function that implicitly
559  * acquires the hold when it allocates the object. Here, object_free() releases
560  * the hold acquired by object_alloc(). Its implicit object_rele() forms a
561  * matching pair with object_hold():
562  *
563  *      void
564  *      object_free(object_t *object)
565  *      {
566  *              container_t *container;
567  *
568  *              ASSERT(object_held(object));
569  *              container = object->o_container;
570  *              mutex_enter(&container->c_objects_lock);
571  *              object->o_container =
572  *                  (void *)((uintptr_t)object->o_container | 0x1);
573  *              list_remove(&container->c_objects, object);
574  *              mutex_exit(&container->c_objects_lock);
575  *              object_rele(object);
576  *              kmem_cache_free(object_cache, object);
577  *      }
578  *
579  * Note that object_free() cannot safely accept an object pointer as an argument
580  * unless the object is already held. Any function that calls object_free()
581  * needs to be carefully noted since it similarly forms a matching pair with
582  * object_hold().
583  *
584  * To complete the picture, the following callback function implements the
585  * general solution by moving objects only if they are currently unheld:
586  *
587  *      static kmem_cbrc_t
588  *      object_move(void *buf, void *newbuf, size_t size, void *arg)
589  *      {
590  *              object_t *op = buf, *np = newbuf;
591  *              container_t *container;
592  *
593  *              container = op->o_container;
594  *              if ((uintptr_t)container & 0x3) {
595  *                      return (KMEM_CBRC_DONT_KNOW);
596  *              }
597  *
598  *	        // Ensure that the container structure does not go away.
599  *              if (container_hold(container) == 0) {
600  *                      return (KMEM_CBRC_DONT_KNOW);
601  *              }
602  *
603  *              mutex_enter(&container->c_objects_lock);
604  *              if (container != op->o_container) {
605  *                      mutex_exit(&container->c_objects_lock);
606  *                      container_rele(container);
607  *                      return (KMEM_CBRC_DONT_KNOW);
608  *              }
609  *
610  *              if (rw_tryenter(OBJECT_RWLOCK(op), RW_WRITER) == 0) {
611  *                      mutex_exit(&container->c_objects_lock);
612  *                      container_rele(container);
613  *                      return (KMEM_CBRC_LATER);
614  *              }
615  *
616  *              object_move_impl(op, np); // critical section
617  *              rw_exit(OBJECT_RWLOCK(op));
618  *
619  *              op->o_container = (void *)((uintptr_t)op->o_container | 0x1);
620  *              list_link_replace(&op->o_link_node, &np->o_link_node);
621  *              mutex_exit(&container->c_objects_lock);
622  *              container_rele(container);
623  *              return (KMEM_CBRC_YES);
624  *      }
625  *
626  * Note that object_move() must invalidate the designated o_container pointer of
627  * the old object in the same way that object_free() does, since kmem will free
628  * the object in response to the KMEM_CBRC_YES return value.
629  *
630  * The lock order in object_move() differs from object_alloc(), which locks
631  * OBJECT_RWLOCK first and &container->c_objects_lock second, but as long as the
632  * callback uses rw_tryenter() (preventing the deadlock described earlier), it's
633  * not a problem. Holding the lock on the object list in the example above
634  * through the entire callback not only prevents the object from going away, it
635  * also allows you to lock the list elsewhere and know that none of its elements
636  * will move during iteration.
637  *
638  * Adding an explicit hold everywhere an object from the cache is used is tricky
639  * and involves much more change to client code than a cache-specific solution
640  * that leverages existing state to decide whether or not an object is
641  * movable. However, this approach has the advantage that no object remains
642  * immovable for any significant length of time, making it extremely unlikely
643  * that long-lived allocations can continue holding slabs hostage; and it works
644  * for any cache.
645  *
646  * 3. Consolidator Implementation
647  *
648  * Once the client supplies a move function that a) recognizes known objects and
649  * b) avoids moving objects that are actively in use, the remaining work is up
650  * to the consolidator to decide which objects to move and when to issue
651  * callbacks.
652  *
653  * The consolidator relies on the fact that a cache's slabs are ordered by
654  * usage. Each slab has a fixed number of objects. Depending on the slab's
655  * "color" (the offset of the first object from the beginning of the slab;
656  * offsets are staggered to mitigate false sharing of cache lines) it is either
657  * the maximum number of objects per slab determined at cache creation time or
658  * else the number closest to the maximum that fits within the space remaining
659  * after the initial offset. A completely allocated slab may contribute some
660  * internal fragmentation (per-slab overhead) but no external fragmentation, so
661  * it is of no interest to the consolidator. At the other extreme, slabs whose
662  * objects have all been freed to the slab are released to the virtual memory
663  * (VM) subsystem (objects freed to magazines are still allocated as far as the
664  * slab is concerned). External fragmentation exists when there are slabs
665  * somewhere between these extremes. A partial slab has at least one but not all
666  * of its objects allocated. The more partial slabs, and the fewer allocated
667  * objects on each of them, the higher the fragmentation. Hence the
668  * consolidator's overall strategy is to reduce the number of partial slabs by
669  * moving allocated objects from the least allocated slabs to the most allocated
670  * slabs.
671  *
672  * Partial slabs are kept in an AVL tree ordered by usage. Completely allocated
673  * slabs are kept separately in an unordered list. Since the majority of slabs
674  * tend to be completely allocated (a typical unfragmented cache may have
675  * thousands of complete slabs and only a single partial slab), separating
676  * complete slabs improves the efficiency of partial slab ordering, since the
677  * complete slabs do not affect the depth or balance of the AVL tree. This
678  * ordered sequence of partial slabs acts as a "free list" supplying objects for
679  * allocation requests.
680  *
681  * Objects are always allocated from the first partial slab in the free list,
682  * where the allocation is most likely to eliminate a partial slab (by
683  * completely allocating it). Conversely, when a single object from a completely
684  * allocated slab is freed to the slab, that slab is added to the front of the
685  * free list. Since most free list activity involves highly allocated slabs
686  * coming and going at the front of the list, slabs tend naturally toward the
687  * ideal order: highly allocated at the front, sparsely allocated at the back.
688  * Slabs with few allocated objects are likely to become completely free if they
689  * keep a safe distance away from the front of the free list. Slab misorders
690  * interfere with the natural tendency of slabs to become completely free or
691  * completely allocated. For example, a slab with a single allocated object
692  * needs only a single free to escape the cache; its natural desire is
693  * frustrated when it finds itself at the front of the list where a second
694  * allocation happens just before the free could have released it. Another slab
695  * with all but one object allocated might have supplied the buffer instead, so
696  * that both (as opposed to neither) of the slabs would have been taken off the
697  * free list.
698  *
699  * Although slabs tend naturally toward the ideal order, misorders allowed by a
700  * simple list implementation defeat the consolidator's strategy of merging
701  * least- and most-allocated slabs. Without an AVL tree to guarantee order, kmem
702  * needs another way to fix misorders to optimize its callback strategy. One
703  * approach is to periodically scan a limited number of slabs, advancing a
704  * marker to hold the current scan position, and to move extreme misorders to
705  * the front or back of the free list and to the front or back of the current
706  * scan range. By making consecutive scan ranges overlap by one slab, the least
707  * allocated slab in the current range can be carried along from the end of one
708  * scan to the start of the next.
709  *
710  * Maintaining partial slabs in an AVL tree relieves kmem of this additional
711  * task, however. Since most of the cache's activity is in the magazine layer,
712  * and allocations from the slab layer represent only a startup cost, the
713  * overhead of maintaining a balanced tree is not a significant concern compared
714  * to the opportunity of reducing complexity by eliminating the partial slab
715  * scanner just described. The overhead of an AVL tree is minimized by
716  * maintaining only partial slabs in the tree and keeping completely allocated
717  * slabs separately in a list. To avoid increasing the size of the slab
718  * structure the AVL linkage pointers are reused for the slab's list linkage,
719  * since the slab will always be either partial or complete, never stored both
720  * ways at the same time. To further minimize the overhead of the AVL tree the
721  * compare function that orders partial slabs by usage divides the range of
722  * allocated object counts into bins such that counts within the same bin are
723  * considered equal. Binning partial slabs makes it less likely that allocating
724  * or freeing a single object will change the slab's order, requiring a tree
725  * reinsertion (an avl_remove() followed by an avl_add(), both potentially
726  * requiring some rebalancing of the tree). Allocation counts closest to
727  * completely free and completely allocated are left unbinned (finely sorted) to
728  * better support the consolidator's strategy of merging slabs at either
729  * extreme.
730  *
731  * 3.1 Assessing Fragmentation and Selecting Candidate Slabs
732  *
733  * The consolidator piggybacks on the kmem maintenance thread and is called on
734  * the same interval as kmem_cache_update(), once per cache every fifteen
735  * seconds. kmem maintains a running count of unallocated objects in the slab
736  * layer (cache_bufslab). The consolidator checks whether that number exceeds
737  * 12.5% (1/8) of the total objects in the cache (cache_buftotal), and whether
738  * there is a significant number of slabs in the cache (arbitrarily a minimum
739  * 101 total slabs). Unused objects that have fallen out of the magazine layer's
740  * working set are included in the assessment, and magazines in the depot are
741  * reaped if those objects would lift cache_bufslab above the fragmentation
742  * threshold. Once the consolidator decides that a cache is fragmented, it looks
743  * for a candidate slab to reclaim, starting at the end of the partial slab free
744  * list and scanning backwards. At first the consolidator is choosy: only a slab
745  * with fewer than 12.5% (1/8) of its objects allocated qualifies (or else a
746  * single allocated object, regardless of percentage). If there is difficulty
747  * finding a candidate slab, kmem raises the allocation threshold incrementally,
748  * up to a maximum 87.5% (7/8), so that eventually the consolidator will reduce
749  * external fragmentation (unused objects on the free list) below 12.5% (1/8),
750  * even in the worst case of every slab in the cache being almost 7/8 allocated.
751  * The threshold can also be lowered incrementally when candidate slabs are easy
752  * to find, and the threshold is reset to the minimum 1/8 as soon as the cache
753  * is no longer fragmented.
754  *
755  * 3.2 Generating Callbacks
756  *
757  * Once an eligible slab is chosen, a callback is generated for every allocated
758  * object on the slab, in the hope that the client will move everything off the
759  * slab and make it reclaimable. Objects selected as move destinations are
760  * chosen from slabs at the front of the free list. Assuming slabs in the ideal
761  * order (most allocated at the front, least allocated at the back) and a
762  * cooperative client, the consolidator will succeed in removing slabs from both
763  * ends of the free list, completely allocating on the one hand and completely
764  * freeing on the other. Objects selected as move destinations are allocated in
765  * the kmem maintenance thread where move requests are enqueued. A separate
766  * callback thread removes pending callbacks from the queue and calls the
767  * client. The separate thread ensures that client code (the move function) does
768  * not interfere with internal kmem maintenance tasks. A map of pending
769  * callbacks keyed by object address (the object to be moved) is checked to
770  * ensure that duplicate callbacks are not generated for the same object.
771  * Allocating the move destination (the object to move to) prevents subsequent
772  * callbacks from selecting the same destination as an earlier pending callback.
773  *
774  * Move requests can also be generated by kmem_cache_reap() when the system is
775  * desperate for memory and by kmem_cache_move_notify(), called by the client to
776  * notify kmem that a move refused earlier with KMEM_CBRC_LATER is now possible.
777  * The map of pending callbacks is protected by the same lock that protects the
778  * slab layer.
779  *
780  * When the system is desperate for memory, kmem does not bother to determine
781  * whether or not the cache exceeds the fragmentation threshold, but tries to
782  * consolidate as many slabs as possible. Normally, the consolidator chews
783  * slowly, one sparsely allocated slab at a time during each maintenance
784  * interval that the cache is fragmented. When desperate, the consolidator
785  * starts at the last partial slab and enqueues callbacks for every allocated
786  * object on every partial slab, working backwards until it reaches the first
787  * partial slab. The first partial slab, meanwhile, advances in pace with the
788  * consolidator as allocations to supply move destinations for the enqueued
789  * callbacks use up the highly allocated slabs at the front of the free list.
790  * Ideally, the overgrown free list collapses like an accordion, starting at
791  * both ends and ending at the center with a single partial slab.
792  *
793  * 3.3 Client Responses
794  *
795  * When the client returns KMEM_CBRC_NO in response to the move callback, kmem
796  * marks the slab that supplied the stuck object non-reclaimable and moves it to
797  * front of the free list. The slab remains marked as long as it remains on the
798  * free list, and it appears more allocated to the partial slab compare function
799  * than any unmarked slab, no matter how many of its objects are allocated.
800  * Since even one immovable object ties up the entire slab, the goal is to
801  * completely allocate any slab that cannot be completely freed. kmem does not
802  * bother generating callbacks to move objects from a marked slab unless the
803  * system is desperate.
804  *
805  * When the client responds KMEM_CBRC_LATER, kmem increments a count for the
806  * slab. If the client responds LATER too many times, kmem disbelieves and
807  * treats the response as a NO. The count is cleared when the slab is taken off
808  * the partial slab list or when the client moves one of the slab's objects.
809  *
810  * 4. Observability
811  *
812  * A kmem cache's external fragmentation is best observed with 'mdb -k' using
813  * the ::kmem_slabs dcmd. For a complete description of the command, enter
814  * '::help kmem_slabs' at the mdb prompt.
815  */
816 
817 #include <sys/kmem_impl.h>
818 #include <sys/vmem_impl.h>
819 #include <sys/param.h>
820 #include <sys/sysmacros.h>
821 #include <sys/vm.h>
822 #include <sys/proc.h>
823 #include <sys/tuneable.h>
824 #include <sys/systm.h>
825 #include <sys/cmn_err.h>
826 #include <sys/debug.h>
827 #include <sys/sdt.h>
828 #include <sys/mutex.h>
829 #include <sys/bitmap.h>
830 #include <sys/atomic.h>
831 #include <sys/kobj.h>
832 #include <sys/disp.h>
833 #include <vm/seg_kmem.h>
834 #include <sys/log.h>
835 #include <sys/callb.h>
836 #include <sys/taskq.h>
837 #include <sys/modctl.h>
838 #include <sys/reboot.h>
839 #include <sys/id32.h>
840 #include <sys/zone.h>
841 #include <sys/netstack.h>
842 #ifdef	DEBUG
843 #include <sys/random.h>
844 #endif
845 
846 extern void streams_msg_init(void);
847 extern int segkp_fromheap;
848 extern void segkp_cache_free(void);
849 extern int callout_init_done;
850 
851 struct kmem_cache_kstat {
852 	kstat_named_t	kmc_buf_size;
853 	kstat_named_t	kmc_align;
854 	kstat_named_t	kmc_chunk_size;
855 	kstat_named_t	kmc_slab_size;
856 	kstat_named_t	kmc_alloc;
857 	kstat_named_t	kmc_alloc_fail;
858 	kstat_named_t	kmc_free;
859 	kstat_named_t	kmc_depot_alloc;
860 	kstat_named_t	kmc_depot_free;
861 	kstat_named_t	kmc_depot_contention;
862 	kstat_named_t	kmc_slab_alloc;
863 	kstat_named_t	kmc_slab_free;
864 	kstat_named_t	kmc_buf_constructed;
865 	kstat_named_t	kmc_buf_avail;
866 	kstat_named_t	kmc_buf_inuse;
867 	kstat_named_t	kmc_buf_total;
868 	kstat_named_t	kmc_buf_max;
869 	kstat_named_t	kmc_slab_create;
870 	kstat_named_t	kmc_slab_destroy;
871 	kstat_named_t	kmc_vmem_source;
872 	kstat_named_t	kmc_hash_size;
873 	kstat_named_t	kmc_hash_lookup_depth;
874 	kstat_named_t	kmc_hash_rescale;
875 	kstat_named_t	kmc_full_magazines;
876 	kstat_named_t	kmc_empty_magazines;
877 	kstat_named_t	kmc_magazine_size;
878 	kstat_named_t	kmc_reap; /* number of kmem_cache_reap() calls */
879 	kstat_named_t	kmc_defrag; /* attempts to defrag all partial slabs */
880 	kstat_named_t	kmc_scan; /* attempts to defrag one partial slab */
881 	kstat_named_t	kmc_move_callbacks; /* sum of yes, no, later, dn, dk */
882 	kstat_named_t	kmc_move_yes;
883 	kstat_named_t	kmc_move_no;
884 	kstat_named_t	kmc_move_later;
885 	kstat_named_t	kmc_move_dont_need;
886 	kstat_named_t	kmc_move_dont_know; /* obj unrecognized by client ... */
887 	kstat_named_t	kmc_move_hunt_found; /* ... but found in mag layer */
888 	kstat_named_t	kmc_move_slabs_freed; /* slabs freed by consolidator */
889 	kstat_named_t	kmc_move_reclaimable; /* buffers, if consolidator ran */
890 } kmem_cache_kstat = {
891 	{ "buf_size",		KSTAT_DATA_UINT64 },
892 	{ "align",		KSTAT_DATA_UINT64 },
893 	{ "chunk_size",		KSTAT_DATA_UINT64 },
894 	{ "slab_size",		KSTAT_DATA_UINT64 },
895 	{ "alloc",		KSTAT_DATA_UINT64 },
896 	{ "alloc_fail",		KSTAT_DATA_UINT64 },
897 	{ "free",		KSTAT_DATA_UINT64 },
898 	{ "depot_alloc",	KSTAT_DATA_UINT64 },
899 	{ "depot_free",		KSTAT_DATA_UINT64 },
900 	{ "depot_contention",	KSTAT_DATA_UINT64 },
901 	{ "slab_alloc",		KSTAT_DATA_UINT64 },
902 	{ "slab_free",		KSTAT_DATA_UINT64 },
903 	{ "buf_constructed",	KSTAT_DATA_UINT64 },
904 	{ "buf_avail",		KSTAT_DATA_UINT64 },
905 	{ "buf_inuse",		KSTAT_DATA_UINT64 },
906 	{ "buf_total",		KSTAT_DATA_UINT64 },
907 	{ "buf_max",		KSTAT_DATA_UINT64 },
908 	{ "slab_create",	KSTAT_DATA_UINT64 },
909 	{ "slab_destroy",	KSTAT_DATA_UINT64 },
910 	{ "vmem_source",	KSTAT_DATA_UINT64 },
911 	{ "hash_size",		KSTAT_DATA_UINT64 },
912 	{ "hash_lookup_depth",	KSTAT_DATA_UINT64 },
913 	{ "hash_rescale",	KSTAT_DATA_UINT64 },
914 	{ "full_magazines",	KSTAT_DATA_UINT64 },
915 	{ "empty_magazines",	KSTAT_DATA_UINT64 },
916 	{ "magazine_size",	KSTAT_DATA_UINT64 },
917 	{ "reap",		KSTAT_DATA_UINT64 },
918 	{ "defrag",		KSTAT_DATA_UINT64 },
919 	{ "scan",		KSTAT_DATA_UINT64 },
920 	{ "move_callbacks",	KSTAT_DATA_UINT64 },
921 	{ "move_yes",		KSTAT_DATA_UINT64 },
922 	{ "move_no",		KSTAT_DATA_UINT64 },
923 	{ "move_later",		KSTAT_DATA_UINT64 },
924 	{ "move_dont_need",	KSTAT_DATA_UINT64 },
925 	{ "move_dont_know",	KSTAT_DATA_UINT64 },
926 	{ "move_hunt_found",	KSTAT_DATA_UINT64 },
927 	{ "move_slabs_freed",	KSTAT_DATA_UINT64 },
928 	{ "move_reclaimable",	KSTAT_DATA_UINT64 },
929 };
930 
931 static kmutex_t kmem_cache_kstat_lock;
932 
933 /*
934  * The default set of caches to back kmem_alloc().
935  * These sizes should be reevaluated periodically.
936  *
937  * We want allocations that are multiples of the coherency granularity
938  * (64 bytes) to be satisfied from a cache which is a multiple of 64
939  * bytes, so that it will be 64-byte aligned.  For all multiples of 64,
940  * the next kmem_cache_size greater than or equal to it must be a
941  * multiple of 64.
942  *
943  * We split the table into two sections:  size <= 4k and size > 4k.  This
944  * saves a lot of space and cache footprint in our cache tables.
945  */
946 static const int kmem_alloc_sizes[] = {
947 	1 * 8,
948 	2 * 8,
949 	3 * 8,
950 	4 * 8,		5 * 8,		6 * 8,		7 * 8,
951 	4 * 16,		5 * 16,		6 * 16,		7 * 16,
952 	4 * 32,		5 * 32,		6 * 32,		7 * 32,
953 	4 * 64,		5 * 64,		6 * 64,		7 * 64,
954 	4 * 128,	5 * 128,	6 * 128,	7 * 128,
955 	P2ALIGN(8192 / 7, 64),
956 	P2ALIGN(8192 / 6, 64),
957 	P2ALIGN(8192 / 5, 64),
958 	P2ALIGN(8192 / 4, 64),
959 	P2ALIGN(8192 / 3, 64),
960 	P2ALIGN(8192 / 2, 64),
961 };
962 
963 static const int kmem_big_alloc_sizes[] = {
964 	2 * 4096,	3 * 4096,
965 	2 * 8192,	3 * 8192,
966 	4 * 8192,	5 * 8192,	6 * 8192,	7 * 8192,
967 	8 * 8192,	9 * 8192,	10 * 8192,	11 * 8192,
968 	12 * 8192,	13 * 8192,	14 * 8192,	15 * 8192,
969 	16 * 8192
970 };
971 
972 #define	KMEM_MAXBUF		4096
973 #define	KMEM_BIG_MAXBUF_32BIT	32768
974 #define	KMEM_BIG_MAXBUF		131072
975 
976 #define	KMEM_BIG_MULTIPLE	4096	/* big_alloc_sizes must be a multiple */
977 #define	KMEM_BIG_SHIFT		12	/* lg(KMEM_BIG_MULTIPLE) */
978 
979 static kmem_cache_t *kmem_alloc_table[KMEM_MAXBUF >> KMEM_ALIGN_SHIFT];
980 static kmem_cache_t *kmem_big_alloc_table[KMEM_BIG_MAXBUF >> KMEM_BIG_SHIFT];
981 
982 #define	KMEM_ALLOC_TABLE_MAX	(KMEM_MAXBUF >> KMEM_ALIGN_SHIFT)
983 static size_t kmem_big_alloc_table_max = 0;	/* # of filled elements */
984 
985 static kmem_magtype_t kmem_magtype[] = {
986 	{ 1,	8,	3200,	65536	},
987 	{ 3,	16,	256,	32768	},
988 	{ 7,	32,	64,	16384	},
989 	{ 15,	64,	0,	8192	},
990 	{ 31,	64,	0,	4096	},
991 	{ 47,	64,	0,	2048	},
992 	{ 63,	64,	0,	1024	},
993 	{ 95,	64,	0,	512	},
994 	{ 143,	64,	0,	0	},
995 };
996 
997 static uint32_t kmem_reaping;
998 static uint32_t kmem_reaping_idspace;
999 
1000 /*
1001  * kmem tunables
1002  */
1003 clock_t kmem_reap_interval;	/* cache reaping rate [15 * HZ ticks] */
1004 int kmem_depot_contention = 3;	/* max failed tryenters per real interval */
1005 pgcnt_t kmem_reapahead = 0;	/* start reaping N pages before pageout */
1006 int kmem_panic = 1;		/* whether to panic on error */
1007 int kmem_logging = 1;		/* kmem_log_enter() override */
1008 uint32_t kmem_mtbf = 0;		/* mean time between failures [default: off] */
1009 size_t kmem_transaction_log_size; /* transaction log size [2% of memory] */
1010 size_t kmem_content_log_size;	/* content log size [2% of memory] */
1011 size_t kmem_failure_log_size;	/* failure log [4 pages per CPU] */
1012 size_t kmem_slab_log_size;	/* slab create log [4 pages per CPU] */
1013 size_t kmem_content_maxsave = 256; /* KMF_CONTENTS max bytes to log */
1014 size_t kmem_lite_minsize = 0;	/* minimum buffer size for KMF_LITE */
1015 size_t kmem_lite_maxalign = 1024; /* maximum buffer alignment for KMF_LITE */
1016 int kmem_lite_pcs = 4;		/* number of PCs to store in KMF_LITE mode */
1017 size_t kmem_maxverify;		/* maximum bytes to inspect in debug routines */
1018 size_t kmem_minfirewall;	/* hardware-enforced redzone threshold */
1019 
1020 #ifdef _LP64
1021 size_t	kmem_max_cached = KMEM_BIG_MAXBUF;	/* maximum kmem_alloc cache */
1022 #else
1023 size_t	kmem_max_cached = KMEM_BIG_MAXBUF_32BIT; /* maximum kmem_alloc cache */
1024 #endif
1025 
1026 #ifdef DEBUG
1027 int kmem_flags = KMF_AUDIT | KMF_DEADBEEF | KMF_REDZONE | KMF_CONTENTS;
1028 #else
1029 int kmem_flags = 0;
1030 #endif
1031 int kmem_ready;
1032 
1033 static kmem_cache_t	*kmem_slab_cache;
1034 static kmem_cache_t	*kmem_bufctl_cache;
1035 static kmem_cache_t	*kmem_bufctl_audit_cache;
1036 
1037 static kmutex_t		kmem_cache_lock;	/* inter-cache linkage only */
1038 static list_t		kmem_caches;
1039 
1040 static taskq_t		*kmem_taskq;
1041 static kmutex_t		kmem_flags_lock;
1042 static vmem_t		*kmem_metadata_arena;
1043 static vmem_t		*kmem_msb_arena;	/* arena for metadata caches */
1044 static vmem_t		*kmem_cache_arena;
1045 static vmem_t		*kmem_hash_arena;
1046 static vmem_t		*kmem_log_arena;
1047 static vmem_t		*kmem_oversize_arena;
1048 static vmem_t		*kmem_va_arena;
1049 static vmem_t		*kmem_default_arena;
1050 static vmem_t		*kmem_firewall_va_arena;
1051 static vmem_t		*kmem_firewall_arena;
1052 
1053 /*
1054  * kmem slab consolidator thresholds (tunables)
1055  */
1056 size_t kmem_frag_minslabs = 101;	/* minimum total slabs */
1057 size_t kmem_frag_numer = 1;		/* free buffers (numerator) */
1058 size_t kmem_frag_denom = KMEM_VOID_FRACTION; /* buffers (denominator) */
1059 /*
1060  * Maximum number of slabs from which to move buffers during a single
1061  * maintenance interval while the system is not low on memory.
1062  */
1063 size_t kmem_reclaim_max_slabs = 1;
1064 /*
1065  * Number of slabs to scan backwards from the end of the partial slab list
1066  * when searching for buffers to relocate.
1067  */
1068 size_t kmem_reclaim_scan_range = 12;
1069 
1070 /* consolidator knobs */
1071 boolean_t kmem_move_noreap;
1072 boolean_t kmem_move_blocked;
1073 boolean_t kmem_move_fulltilt;
1074 boolean_t kmem_move_any_partial;
1075 
1076 #ifdef	DEBUG
1077 /*
1078  * kmem consolidator debug tunables:
1079  * Ensure code coverage by occasionally running the consolidator even when the
1080  * caches are not fragmented (they may never be). These intervals are mean time
1081  * in cache maintenance intervals (kmem_cache_update).
1082  */
1083 uint32_t kmem_mtb_move = 60;	/* defrag 1 slab (~15min) */
1084 uint32_t kmem_mtb_reap = 1800;	/* defrag all slabs (~7.5hrs) */
1085 #endif	/* DEBUG */
1086 
1087 static kmem_cache_t	*kmem_defrag_cache;
1088 static kmem_cache_t	*kmem_move_cache;
1089 static taskq_t		*kmem_move_taskq;
1090 
1091 static void kmem_cache_scan(kmem_cache_t *);
1092 static void kmem_cache_defrag(kmem_cache_t *);
1093 static void kmem_slab_prefill(kmem_cache_t *, kmem_slab_t *);
1094 
1095 
1096 kmem_log_header_t	*kmem_transaction_log;
1097 kmem_log_header_t	*kmem_content_log;
1098 kmem_log_header_t	*kmem_failure_log;
1099 kmem_log_header_t	*kmem_slab_log;
1100 
1101 static int		kmem_lite_count; /* # of PCs in kmem_buftag_lite_t */
1102 
1103 #define	KMEM_BUFTAG_LITE_ENTER(bt, count, caller)			\
1104 	if ((count) > 0) {						\
1105 		pc_t *_s = ((kmem_buftag_lite_t *)(bt))->bt_history;	\
1106 		pc_t *_e;						\
1107 		/* memmove() the old entries down one notch */		\
1108 		for (_e = &_s[(count) - 1]; _e > _s; _e--)		\
1109 			*_e = *(_e - 1);				\
1110 		*_s = (uintptr_t)(caller);				\
1111 	}
1112 
1113 #define	KMERR_MODIFIED	0	/* buffer modified while on freelist */
1114 #define	KMERR_REDZONE	1	/* redzone violation (write past end of buf) */
1115 #define	KMERR_DUPFREE	2	/* freed a buffer twice */
1116 #define	KMERR_BADADDR	3	/* freed a bad (unallocated) address */
1117 #define	KMERR_BADBUFTAG	4	/* buftag corrupted */
1118 #define	KMERR_BADBUFCTL	5	/* bufctl corrupted */
1119 #define	KMERR_BADCACHE	6	/* freed a buffer to the wrong cache */
1120 #define	KMERR_BADSIZE	7	/* alloc size != free size */
1121 #define	KMERR_BADBASE	8	/* buffer base address wrong */
1122 
1123 struct {
1124 	hrtime_t	kmp_timestamp;	/* timestamp of panic */
1125 	int		kmp_error;	/* type of kmem error */
1126 	void		*kmp_buffer;	/* buffer that induced panic */
1127 	void		*kmp_realbuf;	/* real start address for buffer */
1128 	kmem_cache_t	*kmp_cache;	/* buffer's cache according to client */
1129 	kmem_cache_t	*kmp_realcache;	/* actual cache containing buffer */
1130 	kmem_slab_t	*kmp_slab;	/* slab accoring to kmem_findslab() */
1131 	kmem_bufctl_t	*kmp_bufctl;	/* bufctl */
1132 } kmem_panic_info;
1133 
1134 
1135 static void
1136 copy_pattern(uint64_t pattern, void *buf_arg, size_t size)
1137 {
1138 	uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1139 	uint64_t *buf = buf_arg;
1140 
1141 	while (buf < bufend)
1142 		*buf++ = pattern;
1143 }
1144 
1145 static void *
1146 verify_pattern(uint64_t pattern, void *buf_arg, size_t size)
1147 {
1148 	uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1149 	uint64_t *buf;
1150 
1151 	for (buf = buf_arg; buf < bufend; buf++)
1152 		if (*buf != pattern)
1153 			return (buf);
1154 	return (NULL);
1155 }
1156 
1157 static void *
1158 verify_and_copy_pattern(uint64_t old, uint64_t new, void *buf_arg, size_t size)
1159 {
1160 	uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1161 	uint64_t *buf;
1162 
1163 	for (buf = buf_arg; buf < bufend; buf++) {
1164 		if (*buf != old) {
1165 			copy_pattern(old, buf_arg,
1166 			    (char *)buf - (char *)buf_arg);
1167 			return (buf);
1168 		}
1169 		*buf = new;
1170 	}
1171 
1172 	return (NULL);
1173 }
1174 
1175 static void
1176 kmem_cache_applyall(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1177 {
1178 	kmem_cache_t *cp;
1179 
1180 	mutex_enter(&kmem_cache_lock);
1181 	for (cp = list_head(&kmem_caches); cp != NULL;
1182 	    cp = list_next(&kmem_caches, cp))
1183 		if (tq != NULL)
1184 			(void) taskq_dispatch(tq, (task_func_t *)func, cp,
1185 			    tqflag);
1186 		else
1187 			func(cp);
1188 	mutex_exit(&kmem_cache_lock);
1189 }
1190 
1191 static void
1192 kmem_cache_applyall_id(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1193 {
1194 	kmem_cache_t *cp;
1195 
1196 	mutex_enter(&kmem_cache_lock);
1197 	for (cp = list_head(&kmem_caches); cp != NULL;
1198 	    cp = list_next(&kmem_caches, cp)) {
1199 		if (!(cp->cache_cflags & KMC_IDENTIFIER))
1200 			continue;
1201 		if (tq != NULL)
1202 			(void) taskq_dispatch(tq, (task_func_t *)func, cp,
1203 			    tqflag);
1204 		else
1205 			func(cp);
1206 	}
1207 	mutex_exit(&kmem_cache_lock);
1208 }
1209 
1210 /*
1211  * Debugging support.  Given a buffer address, find its slab.
1212  */
1213 static kmem_slab_t *
1214 kmem_findslab(kmem_cache_t *cp, void *buf)
1215 {
1216 	kmem_slab_t *sp;
1217 
1218 	mutex_enter(&cp->cache_lock);
1219 	for (sp = list_head(&cp->cache_complete_slabs); sp != NULL;
1220 	    sp = list_next(&cp->cache_complete_slabs, sp)) {
1221 		if (KMEM_SLAB_MEMBER(sp, buf)) {
1222 			mutex_exit(&cp->cache_lock);
1223 			return (sp);
1224 		}
1225 	}
1226 	for (sp = avl_first(&cp->cache_partial_slabs); sp != NULL;
1227 	    sp = AVL_NEXT(&cp->cache_partial_slabs, sp)) {
1228 		if (KMEM_SLAB_MEMBER(sp, buf)) {
1229 			mutex_exit(&cp->cache_lock);
1230 			return (sp);
1231 		}
1232 	}
1233 	mutex_exit(&cp->cache_lock);
1234 
1235 	return (NULL);
1236 }
1237 
1238 static void
1239 kmem_error(int error, kmem_cache_t *cparg, void *bufarg)
1240 {
1241 	kmem_buftag_t *btp = NULL;
1242 	kmem_bufctl_t *bcp = NULL;
1243 	kmem_cache_t *cp = cparg;
1244 	kmem_slab_t *sp;
1245 	uint64_t *off;
1246 	void *buf = bufarg;
1247 
1248 	kmem_logging = 0;	/* stop logging when a bad thing happens */
1249 
1250 	kmem_panic_info.kmp_timestamp = gethrtime();
1251 
1252 	sp = kmem_findslab(cp, buf);
1253 	if (sp == NULL) {
1254 		for (cp = list_tail(&kmem_caches); cp != NULL;
1255 		    cp = list_prev(&kmem_caches, cp)) {
1256 			if ((sp = kmem_findslab(cp, buf)) != NULL)
1257 				break;
1258 		}
1259 	}
1260 
1261 	if (sp == NULL) {
1262 		cp = NULL;
1263 		error = KMERR_BADADDR;
1264 	} else {
1265 		if (cp != cparg)
1266 			error = KMERR_BADCACHE;
1267 		else
1268 			buf = (char *)bufarg - ((uintptr_t)bufarg -
1269 			    (uintptr_t)sp->slab_base) % cp->cache_chunksize;
1270 		if (buf != bufarg)
1271 			error = KMERR_BADBASE;
1272 		if (cp->cache_flags & KMF_BUFTAG)
1273 			btp = KMEM_BUFTAG(cp, buf);
1274 		if (cp->cache_flags & KMF_HASH) {
1275 			mutex_enter(&cp->cache_lock);
1276 			for (bcp = *KMEM_HASH(cp, buf); bcp; bcp = bcp->bc_next)
1277 				if (bcp->bc_addr == buf)
1278 					break;
1279 			mutex_exit(&cp->cache_lock);
1280 			if (bcp == NULL && btp != NULL)
1281 				bcp = btp->bt_bufctl;
1282 			if (kmem_findslab(cp->cache_bufctl_cache, bcp) ==
1283 			    NULL || P2PHASE((uintptr_t)bcp, KMEM_ALIGN) ||
1284 			    bcp->bc_addr != buf) {
1285 				error = KMERR_BADBUFCTL;
1286 				bcp = NULL;
1287 			}
1288 		}
1289 	}
1290 
1291 	kmem_panic_info.kmp_error = error;
1292 	kmem_panic_info.kmp_buffer = bufarg;
1293 	kmem_panic_info.kmp_realbuf = buf;
1294 	kmem_panic_info.kmp_cache = cparg;
1295 	kmem_panic_info.kmp_realcache = cp;
1296 	kmem_panic_info.kmp_slab = sp;
1297 	kmem_panic_info.kmp_bufctl = bcp;
1298 
1299 	printf("kernel memory allocator: ");
1300 
1301 	switch (error) {
1302 
1303 	case KMERR_MODIFIED:
1304 		printf("buffer modified after being freed\n");
1305 		off = verify_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1306 		if (off == NULL)	/* shouldn't happen */
1307 			off = buf;
1308 		printf("modification occurred at offset 0x%lx "
1309 		    "(0x%llx replaced by 0x%llx)\n",
1310 		    (uintptr_t)off - (uintptr_t)buf,
1311 		    (longlong_t)KMEM_FREE_PATTERN, (longlong_t)*off);
1312 		break;
1313 
1314 	case KMERR_REDZONE:
1315 		printf("redzone violation: write past end of buffer\n");
1316 		break;
1317 
1318 	case KMERR_BADADDR:
1319 		printf("invalid free: buffer not in cache\n");
1320 		break;
1321 
1322 	case KMERR_DUPFREE:
1323 		printf("duplicate free: buffer freed twice\n");
1324 		break;
1325 
1326 	case KMERR_BADBUFTAG:
1327 		printf("boundary tag corrupted\n");
1328 		printf("bcp ^ bxstat = %lx, should be %lx\n",
1329 		    (intptr_t)btp->bt_bufctl ^ btp->bt_bxstat,
1330 		    KMEM_BUFTAG_FREE);
1331 		break;
1332 
1333 	case KMERR_BADBUFCTL:
1334 		printf("bufctl corrupted\n");
1335 		break;
1336 
1337 	case KMERR_BADCACHE:
1338 		printf("buffer freed to wrong cache\n");
1339 		printf("buffer was allocated from %s,\n", cp->cache_name);
1340 		printf("caller attempting free to %s.\n", cparg->cache_name);
1341 		break;
1342 
1343 	case KMERR_BADSIZE:
1344 		printf("bad free: free size (%u) != alloc size (%u)\n",
1345 		    KMEM_SIZE_DECODE(((uint32_t *)btp)[0]),
1346 		    KMEM_SIZE_DECODE(((uint32_t *)btp)[1]));
1347 		break;
1348 
1349 	case KMERR_BADBASE:
1350 		printf("bad free: free address (%p) != alloc address (%p)\n",
1351 		    bufarg, buf);
1352 		break;
1353 	}
1354 
1355 	printf("buffer=%p  bufctl=%p  cache: %s\n",
1356 	    bufarg, (void *)bcp, cparg->cache_name);
1357 
1358 	if (bcp != NULL && (cp->cache_flags & KMF_AUDIT) &&
1359 	    error != KMERR_BADBUFCTL) {
1360 		int d;
1361 		timestruc_t ts;
1362 		kmem_bufctl_audit_t *bcap = (kmem_bufctl_audit_t *)bcp;
1363 
1364 		hrt2ts(kmem_panic_info.kmp_timestamp - bcap->bc_timestamp, &ts);
1365 		printf("previous transaction on buffer %p:\n", buf);
1366 		printf("thread=%p  time=T-%ld.%09ld  slab=%p  cache: %s\n",
1367 		    (void *)bcap->bc_thread, ts.tv_sec, ts.tv_nsec,
1368 		    (void *)sp, cp->cache_name);
1369 		for (d = 0; d < MIN(bcap->bc_depth, KMEM_STACK_DEPTH); d++) {
1370 			ulong_t off;
1371 			char *sym = kobj_getsymname(bcap->bc_stack[d], &off);
1372 			printf("%s+%lx\n", sym ? sym : "?", off);
1373 		}
1374 	}
1375 	if (kmem_panic > 0)
1376 		panic("kernel heap corruption detected");
1377 	if (kmem_panic == 0)
1378 		debug_enter(NULL);
1379 	kmem_logging = 1;	/* resume logging */
1380 }
1381 
1382 static kmem_log_header_t *
1383 kmem_log_init(size_t logsize)
1384 {
1385 	kmem_log_header_t *lhp;
1386 	int nchunks = 4 * max_ncpus;
1387 	size_t lhsize = (size_t)&((kmem_log_header_t *)0)->lh_cpu[max_ncpus];
1388 	int i;
1389 
1390 	/*
1391 	 * Make sure that lhp->lh_cpu[] is nicely aligned
1392 	 * to prevent false sharing of cache lines.
1393 	 */
1394 	lhsize = P2ROUNDUP(lhsize, KMEM_ALIGN);
1395 	lhp = vmem_xalloc(kmem_log_arena, lhsize, 64, P2NPHASE(lhsize, 64), 0,
1396 	    NULL, NULL, VM_SLEEP);
1397 	bzero(lhp, lhsize);
1398 
1399 	mutex_init(&lhp->lh_lock, NULL, MUTEX_DEFAULT, NULL);
1400 	lhp->lh_nchunks = nchunks;
1401 	lhp->lh_chunksize = P2ROUNDUP(logsize / nchunks + 1, PAGESIZE);
1402 	lhp->lh_base = vmem_alloc(kmem_log_arena,
1403 	    lhp->lh_chunksize * nchunks, VM_SLEEP);
1404 	lhp->lh_free = vmem_alloc(kmem_log_arena,
1405 	    nchunks * sizeof (int), VM_SLEEP);
1406 	bzero(lhp->lh_base, lhp->lh_chunksize * nchunks);
1407 
1408 	for (i = 0; i < max_ncpus; i++) {
1409 		kmem_cpu_log_header_t *clhp = &lhp->lh_cpu[i];
1410 		mutex_init(&clhp->clh_lock, NULL, MUTEX_DEFAULT, NULL);
1411 		clhp->clh_chunk = i;
1412 	}
1413 
1414 	for (i = max_ncpus; i < nchunks; i++)
1415 		lhp->lh_free[i] = i;
1416 
1417 	lhp->lh_head = max_ncpus;
1418 	lhp->lh_tail = 0;
1419 
1420 	return (lhp);
1421 }
1422 
1423 static void *
1424 kmem_log_enter(kmem_log_header_t *lhp, void *data, size_t size)
1425 {
1426 	void *logspace;
1427 	kmem_cpu_log_header_t *clhp = &lhp->lh_cpu[CPU->cpu_seqid];
1428 
1429 	if (lhp == NULL || kmem_logging == 0 || panicstr)
1430 		return (NULL);
1431 
1432 	mutex_enter(&clhp->clh_lock);
1433 	clhp->clh_hits++;
1434 	if (size > clhp->clh_avail) {
1435 		mutex_enter(&lhp->lh_lock);
1436 		lhp->lh_hits++;
1437 		lhp->lh_free[lhp->lh_tail] = clhp->clh_chunk;
1438 		lhp->lh_tail = (lhp->lh_tail + 1) % lhp->lh_nchunks;
1439 		clhp->clh_chunk = lhp->lh_free[lhp->lh_head];
1440 		lhp->lh_head = (lhp->lh_head + 1) % lhp->lh_nchunks;
1441 		clhp->clh_current = lhp->lh_base +
1442 		    clhp->clh_chunk * lhp->lh_chunksize;
1443 		clhp->clh_avail = lhp->lh_chunksize;
1444 		if (size > lhp->lh_chunksize)
1445 			size = lhp->lh_chunksize;
1446 		mutex_exit(&lhp->lh_lock);
1447 	}
1448 	logspace = clhp->clh_current;
1449 	clhp->clh_current += size;
1450 	clhp->clh_avail -= size;
1451 	bcopy(data, logspace, size);
1452 	mutex_exit(&clhp->clh_lock);
1453 	return (logspace);
1454 }
1455 
1456 #define	KMEM_AUDIT(lp, cp, bcp)						\
1457 {									\
1458 	kmem_bufctl_audit_t *_bcp = (kmem_bufctl_audit_t *)(bcp);	\
1459 	_bcp->bc_timestamp = gethrtime();				\
1460 	_bcp->bc_thread = curthread;					\
1461 	_bcp->bc_depth = getpcstack(_bcp->bc_stack, KMEM_STACK_DEPTH);	\
1462 	_bcp->bc_lastlog = kmem_log_enter((lp), _bcp, sizeof (*_bcp));	\
1463 }
1464 
1465 static void
1466 kmem_log_event(kmem_log_header_t *lp, kmem_cache_t *cp,
1467     kmem_slab_t *sp, void *addr)
1468 {
1469 	kmem_bufctl_audit_t bca;
1470 
1471 	bzero(&bca, sizeof (kmem_bufctl_audit_t));
1472 	bca.bc_addr = addr;
1473 	bca.bc_slab = sp;
1474 	bca.bc_cache = cp;
1475 	KMEM_AUDIT(lp, cp, &bca);
1476 }
1477 
1478 /*
1479  * Create a new slab for cache cp.
1480  */
1481 static kmem_slab_t *
1482 kmem_slab_create(kmem_cache_t *cp, int kmflag)
1483 {
1484 	size_t slabsize = cp->cache_slabsize;
1485 	size_t chunksize = cp->cache_chunksize;
1486 	int cache_flags = cp->cache_flags;
1487 	size_t color, chunks;
1488 	char *buf, *slab;
1489 	kmem_slab_t *sp;
1490 	kmem_bufctl_t *bcp;
1491 	vmem_t *vmp = cp->cache_arena;
1492 
1493 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1494 
1495 	color = cp->cache_color + cp->cache_align;
1496 	if (color > cp->cache_maxcolor)
1497 		color = cp->cache_mincolor;
1498 	cp->cache_color = color;
1499 
1500 	slab = vmem_alloc(vmp, slabsize, kmflag & KM_VMFLAGS);
1501 
1502 	if (slab == NULL)
1503 		goto vmem_alloc_failure;
1504 
1505 	ASSERT(P2PHASE((uintptr_t)slab, vmp->vm_quantum) == 0);
1506 
1507 	/*
1508 	 * Reverify what was already checked in kmem_cache_set_move(), since the
1509 	 * consolidator depends (for correctness) on slabs being initialized
1510 	 * with the 0xbaddcafe memory pattern (setting a low order bit usable by
1511 	 * clients to distinguish uninitialized memory from known objects).
1512 	 */
1513 	ASSERT((cp->cache_move == NULL) || !(cp->cache_cflags & KMC_NOTOUCH));
1514 	if (!(cp->cache_cflags & KMC_NOTOUCH))
1515 		copy_pattern(KMEM_UNINITIALIZED_PATTERN, slab, slabsize);
1516 
1517 	if (cache_flags & KMF_HASH) {
1518 		if ((sp = kmem_cache_alloc(kmem_slab_cache, kmflag)) == NULL)
1519 			goto slab_alloc_failure;
1520 		chunks = (slabsize - color) / chunksize;
1521 	} else {
1522 		sp = KMEM_SLAB(cp, slab);
1523 		chunks = (slabsize - sizeof (kmem_slab_t) - color) / chunksize;
1524 	}
1525 
1526 	sp->slab_cache	= cp;
1527 	sp->slab_head	= NULL;
1528 	sp->slab_refcnt	= 0;
1529 	sp->slab_base	= buf = slab + color;
1530 	sp->slab_chunks	= chunks;
1531 	sp->slab_stuck_offset = (uint32_t)-1;
1532 	sp->slab_later_count = 0;
1533 	sp->slab_flags = 0;
1534 
1535 	ASSERT(chunks > 0);
1536 	while (chunks-- != 0) {
1537 		if (cache_flags & KMF_HASH) {
1538 			bcp = kmem_cache_alloc(cp->cache_bufctl_cache, kmflag);
1539 			if (bcp == NULL)
1540 				goto bufctl_alloc_failure;
1541 			if (cache_flags & KMF_AUDIT) {
1542 				kmem_bufctl_audit_t *bcap =
1543 				    (kmem_bufctl_audit_t *)bcp;
1544 				bzero(bcap, sizeof (kmem_bufctl_audit_t));
1545 				bcap->bc_cache = cp;
1546 			}
1547 			bcp->bc_addr = buf;
1548 			bcp->bc_slab = sp;
1549 		} else {
1550 			bcp = KMEM_BUFCTL(cp, buf);
1551 		}
1552 		if (cache_flags & KMF_BUFTAG) {
1553 			kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1554 			btp->bt_redzone = KMEM_REDZONE_PATTERN;
1555 			btp->bt_bufctl = bcp;
1556 			btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1557 			if (cache_flags & KMF_DEADBEEF) {
1558 				copy_pattern(KMEM_FREE_PATTERN, buf,
1559 				    cp->cache_verify);
1560 			}
1561 		}
1562 		bcp->bc_next = sp->slab_head;
1563 		sp->slab_head = bcp;
1564 		buf += chunksize;
1565 	}
1566 
1567 	kmem_log_event(kmem_slab_log, cp, sp, slab);
1568 
1569 	return (sp);
1570 
1571 bufctl_alloc_failure:
1572 
1573 	while ((bcp = sp->slab_head) != NULL) {
1574 		sp->slab_head = bcp->bc_next;
1575 		kmem_cache_free(cp->cache_bufctl_cache, bcp);
1576 	}
1577 	kmem_cache_free(kmem_slab_cache, sp);
1578 
1579 slab_alloc_failure:
1580 
1581 	vmem_free(vmp, slab, slabsize);
1582 
1583 vmem_alloc_failure:
1584 
1585 	kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1586 	atomic_inc_64(&cp->cache_alloc_fail);
1587 
1588 	return (NULL);
1589 }
1590 
1591 /*
1592  * Destroy a slab.
1593  */
1594 static void
1595 kmem_slab_destroy(kmem_cache_t *cp, kmem_slab_t *sp)
1596 {
1597 	vmem_t *vmp = cp->cache_arena;
1598 	void *slab = (void *)P2ALIGN((uintptr_t)sp->slab_base, vmp->vm_quantum);
1599 
1600 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1601 	ASSERT(sp->slab_refcnt == 0);
1602 
1603 	if (cp->cache_flags & KMF_HASH) {
1604 		kmem_bufctl_t *bcp;
1605 		while ((bcp = sp->slab_head) != NULL) {
1606 			sp->slab_head = bcp->bc_next;
1607 			kmem_cache_free(cp->cache_bufctl_cache, bcp);
1608 		}
1609 		kmem_cache_free(kmem_slab_cache, sp);
1610 	}
1611 	vmem_free(vmp, slab, cp->cache_slabsize);
1612 }
1613 
1614 static void *
1615 kmem_slab_alloc_impl(kmem_cache_t *cp, kmem_slab_t *sp, boolean_t prefill)
1616 {
1617 	kmem_bufctl_t *bcp, **hash_bucket;
1618 	void *buf;
1619 	boolean_t new_slab = (sp->slab_refcnt == 0);
1620 
1621 	ASSERT(MUTEX_HELD(&cp->cache_lock));
1622 	/*
1623 	 * kmem_slab_alloc() drops cache_lock when it creates a new slab, so we
1624 	 * can't ASSERT(avl_is_empty(&cp->cache_partial_slabs)) here when the
1625 	 * slab is newly created.
1626 	 */
1627 	ASSERT(new_slab || (KMEM_SLAB_IS_PARTIAL(sp) &&
1628 	    (sp == avl_first(&cp->cache_partial_slabs))));
1629 	ASSERT(sp->slab_cache == cp);
1630 
1631 	cp->cache_slab_alloc++;
1632 	cp->cache_bufslab--;
1633 	sp->slab_refcnt++;
1634 
1635 	bcp = sp->slab_head;
1636 	sp->slab_head = bcp->bc_next;
1637 
1638 	if (cp->cache_flags & KMF_HASH) {
1639 		/*
1640 		 * Add buffer to allocated-address hash table.
1641 		 */
1642 		buf = bcp->bc_addr;
1643 		hash_bucket = KMEM_HASH(cp, buf);
1644 		bcp->bc_next = *hash_bucket;
1645 		*hash_bucket = bcp;
1646 		if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1647 			KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1648 		}
1649 	} else {
1650 		buf = KMEM_BUF(cp, bcp);
1651 	}
1652 
1653 	ASSERT(KMEM_SLAB_MEMBER(sp, buf));
1654 
1655 	if (sp->slab_head == NULL) {
1656 		ASSERT(KMEM_SLAB_IS_ALL_USED(sp));
1657 		if (new_slab) {
1658 			ASSERT(sp->slab_chunks == 1);
1659 		} else {
1660 			ASSERT(sp->slab_chunks > 1); /* the slab was partial */
1661 			avl_remove(&cp->cache_partial_slabs, sp);
1662 			sp->slab_later_count = 0; /* clear history */
1663 			sp->slab_flags &= ~KMEM_SLAB_NOMOVE;
1664 			sp->slab_stuck_offset = (uint32_t)-1;
1665 		}
1666 		list_insert_head(&cp->cache_complete_slabs, sp);
1667 		cp->cache_complete_slab_count++;
1668 		return (buf);
1669 	}
1670 
1671 	ASSERT(KMEM_SLAB_IS_PARTIAL(sp));
1672 	/*
1673 	 * Peek to see if the magazine layer is enabled before
1674 	 * we prefill.  We're not holding the cpu cache lock,
1675 	 * so the peek could be wrong, but there's no harm in it.
1676 	 */
1677 	if (new_slab && prefill && (cp->cache_flags & KMF_PREFILL) &&
1678 	    (KMEM_CPU_CACHE(cp)->cc_magsize != 0))  {
1679 		kmem_slab_prefill(cp, sp);
1680 		return (buf);
1681 	}
1682 
1683 	if (new_slab) {
1684 		avl_add(&cp->cache_partial_slabs, sp);
1685 		return (buf);
1686 	}
1687 
1688 	/*
1689 	 * The slab is now more allocated than it was, so the
1690 	 * order remains unchanged.
1691 	 */
1692 	ASSERT(!avl_update(&cp->cache_partial_slabs, sp));
1693 	return (buf);
1694 }
1695 
1696 /*
1697  * Allocate a raw (unconstructed) buffer from cp's slab layer.
1698  */
1699 static void *
1700 kmem_slab_alloc(kmem_cache_t *cp, int kmflag)
1701 {
1702 	kmem_slab_t *sp;
1703 	void *buf;
1704 	boolean_t test_destructor;
1705 
1706 	mutex_enter(&cp->cache_lock);
1707 	test_destructor = (cp->cache_slab_alloc == 0);
1708 	sp = avl_first(&cp->cache_partial_slabs);
1709 	if (sp == NULL) {
1710 		ASSERT(cp->cache_bufslab == 0);
1711 
1712 		/*
1713 		 * The freelist is empty.  Create a new slab.
1714 		 */
1715 		mutex_exit(&cp->cache_lock);
1716 		if ((sp = kmem_slab_create(cp, kmflag)) == NULL) {
1717 			return (NULL);
1718 		}
1719 		mutex_enter(&cp->cache_lock);
1720 		cp->cache_slab_create++;
1721 		if ((cp->cache_buftotal += sp->slab_chunks) > cp->cache_bufmax)
1722 			cp->cache_bufmax = cp->cache_buftotal;
1723 		cp->cache_bufslab += sp->slab_chunks;
1724 	}
1725 
1726 	buf = kmem_slab_alloc_impl(cp, sp, B_TRUE);
1727 	ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1728 	    (cp->cache_complete_slab_count +
1729 	    avl_numnodes(&cp->cache_partial_slabs) +
1730 	    (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1731 	mutex_exit(&cp->cache_lock);
1732 
1733 	if (test_destructor && cp->cache_destructor != NULL) {
1734 		/*
1735 		 * On the first kmem_slab_alloc(), assert that it is valid to
1736 		 * call the destructor on a newly constructed object without any
1737 		 * client involvement.
1738 		 */
1739 		if ((cp->cache_constructor == NULL) ||
1740 		    cp->cache_constructor(buf, cp->cache_private,
1741 		    kmflag) == 0) {
1742 			cp->cache_destructor(buf, cp->cache_private);
1743 		}
1744 		copy_pattern(KMEM_UNINITIALIZED_PATTERN, buf,
1745 		    cp->cache_bufsize);
1746 		if (cp->cache_flags & KMF_DEADBEEF) {
1747 			copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1748 		}
1749 	}
1750 
1751 	return (buf);
1752 }
1753 
1754 static void kmem_slab_move_yes(kmem_cache_t *, kmem_slab_t *, void *);
1755 
1756 /*
1757  * Free a raw (unconstructed) buffer to cp's slab layer.
1758  */
1759 static void
1760 kmem_slab_free(kmem_cache_t *cp, void *buf)
1761 {
1762 	kmem_slab_t *sp;
1763 	kmem_bufctl_t *bcp, **prev_bcpp;
1764 
1765 	ASSERT(buf != NULL);
1766 
1767 	mutex_enter(&cp->cache_lock);
1768 	cp->cache_slab_free++;
1769 
1770 	if (cp->cache_flags & KMF_HASH) {
1771 		/*
1772 		 * Look up buffer in allocated-address hash table.
1773 		 */
1774 		prev_bcpp = KMEM_HASH(cp, buf);
1775 		while ((bcp = *prev_bcpp) != NULL) {
1776 			if (bcp->bc_addr == buf) {
1777 				*prev_bcpp = bcp->bc_next;
1778 				sp = bcp->bc_slab;
1779 				break;
1780 			}
1781 			cp->cache_lookup_depth++;
1782 			prev_bcpp = &bcp->bc_next;
1783 		}
1784 	} else {
1785 		bcp = KMEM_BUFCTL(cp, buf);
1786 		sp = KMEM_SLAB(cp, buf);
1787 	}
1788 
1789 	if (bcp == NULL || sp->slab_cache != cp || !KMEM_SLAB_MEMBER(sp, buf)) {
1790 		mutex_exit(&cp->cache_lock);
1791 		kmem_error(KMERR_BADADDR, cp, buf);
1792 		return;
1793 	}
1794 
1795 	if (KMEM_SLAB_OFFSET(sp, buf) == sp->slab_stuck_offset) {
1796 		/*
1797 		 * If this is the buffer that prevented the consolidator from
1798 		 * clearing the slab, we can reset the slab flags now that the
1799 		 * buffer is freed. (It makes sense to do this in
1800 		 * kmem_cache_free(), where the client gives up ownership of the
1801 		 * buffer, but on the hot path the test is too expensive.)
1802 		 */
1803 		kmem_slab_move_yes(cp, sp, buf);
1804 	}
1805 
1806 	if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1807 		if (cp->cache_flags & KMF_CONTENTS)
1808 			((kmem_bufctl_audit_t *)bcp)->bc_contents =
1809 			    kmem_log_enter(kmem_content_log, buf,
1810 			    cp->cache_contents);
1811 		KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1812 	}
1813 
1814 	bcp->bc_next = sp->slab_head;
1815 	sp->slab_head = bcp;
1816 
1817 	cp->cache_bufslab++;
1818 	ASSERT(sp->slab_refcnt >= 1);
1819 
1820 	if (--sp->slab_refcnt == 0) {
1821 		/*
1822 		 * There are no outstanding allocations from this slab,
1823 		 * so we can reclaim the memory.
1824 		 */
1825 		if (sp->slab_chunks == 1) {
1826 			list_remove(&cp->cache_complete_slabs, sp);
1827 			cp->cache_complete_slab_count--;
1828 		} else {
1829 			avl_remove(&cp->cache_partial_slabs, sp);
1830 		}
1831 
1832 		cp->cache_buftotal -= sp->slab_chunks;
1833 		cp->cache_bufslab -= sp->slab_chunks;
1834 		/*
1835 		 * Defer releasing the slab to the virtual memory subsystem
1836 		 * while there is a pending move callback, since we guarantee
1837 		 * that buffers passed to the move callback have only been
1838 		 * touched by kmem or by the client itself. Since the memory
1839 		 * patterns baddcafe (uninitialized) and deadbeef (freed) both
1840 		 * set at least one of the two lowest order bits, the client can
1841 		 * test those bits in the move callback to determine whether or
1842 		 * not it knows about the buffer (assuming that the client also
1843 		 * sets one of those low order bits whenever it frees a buffer).
1844 		 */
1845 		if (cp->cache_defrag == NULL ||
1846 		    (avl_is_empty(&cp->cache_defrag->kmd_moves_pending) &&
1847 		    !(sp->slab_flags & KMEM_SLAB_MOVE_PENDING))) {
1848 			cp->cache_slab_destroy++;
1849 			mutex_exit(&cp->cache_lock);
1850 			kmem_slab_destroy(cp, sp);
1851 		} else {
1852 			list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
1853 			/*
1854 			 * Slabs are inserted at both ends of the deadlist to
1855 			 * distinguish between slabs freed while move callbacks
1856 			 * are pending (list head) and a slab freed while the
1857 			 * lock is dropped in kmem_move_buffers() (list tail) so
1858 			 * that in both cases slab_destroy() is called from the
1859 			 * right context.
1860 			 */
1861 			if (sp->slab_flags & KMEM_SLAB_MOVE_PENDING) {
1862 				list_insert_tail(deadlist, sp);
1863 			} else {
1864 				list_insert_head(deadlist, sp);
1865 			}
1866 			cp->cache_defrag->kmd_deadcount++;
1867 			mutex_exit(&cp->cache_lock);
1868 		}
1869 		return;
1870 	}
1871 
1872 	if (bcp->bc_next == NULL) {
1873 		/* Transition the slab from completely allocated to partial. */
1874 		ASSERT(sp->slab_refcnt == (sp->slab_chunks - 1));
1875 		ASSERT(sp->slab_chunks > 1);
1876 		list_remove(&cp->cache_complete_slabs, sp);
1877 		cp->cache_complete_slab_count--;
1878 		avl_add(&cp->cache_partial_slabs, sp);
1879 	} else {
1880 		(void) avl_update_gt(&cp->cache_partial_slabs, sp);
1881 	}
1882 
1883 	ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1884 	    (cp->cache_complete_slab_count +
1885 	    avl_numnodes(&cp->cache_partial_slabs) +
1886 	    (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1887 	mutex_exit(&cp->cache_lock);
1888 }
1889 
1890 /*
1891  * Return -1 if kmem_error, 1 if constructor fails, 0 if successful.
1892  */
1893 static int
1894 kmem_cache_alloc_debug(kmem_cache_t *cp, void *buf, int kmflag, int construct,
1895     caddr_t caller)
1896 {
1897 	kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1898 	kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
1899 	uint32_t mtbf;
1900 
1901 	if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
1902 		kmem_error(KMERR_BADBUFTAG, cp, buf);
1903 		return (-1);
1904 	}
1905 
1906 	btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_ALLOC;
1907 
1908 	if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
1909 		kmem_error(KMERR_BADBUFCTL, cp, buf);
1910 		return (-1);
1911 	}
1912 
1913 	if (cp->cache_flags & KMF_DEADBEEF) {
1914 		if (!construct && (cp->cache_flags & KMF_LITE)) {
1915 			if (*(uint64_t *)buf != KMEM_FREE_PATTERN) {
1916 				kmem_error(KMERR_MODIFIED, cp, buf);
1917 				return (-1);
1918 			}
1919 			if (cp->cache_constructor != NULL)
1920 				*(uint64_t *)buf = btp->bt_redzone;
1921 			else
1922 				*(uint64_t *)buf = KMEM_UNINITIALIZED_PATTERN;
1923 		} else {
1924 			construct = 1;
1925 			if (verify_and_copy_pattern(KMEM_FREE_PATTERN,
1926 			    KMEM_UNINITIALIZED_PATTERN, buf,
1927 			    cp->cache_verify)) {
1928 				kmem_error(KMERR_MODIFIED, cp, buf);
1929 				return (-1);
1930 			}
1931 		}
1932 	}
1933 	btp->bt_redzone = KMEM_REDZONE_PATTERN;
1934 
1935 	if ((mtbf = kmem_mtbf | cp->cache_mtbf) != 0 &&
1936 	    gethrtime() % mtbf == 0 &&
1937 	    (kmflag & (KM_NOSLEEP | KM_PANIC)) == KM_NOSLEEP) {
1938 		kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1939 		if (!construct && cp->cache_destructor != NULL)
1940 			cp->cache_destructor(buf, cp->cache_private);
1941 	} else {
1942 		mtbf = 0;
1943 	}
1944 
1945 	if (mtbf || (construct && cp->cache_constructor != NULL &&
1946 	    cp->cache_constructor(buf, cp->cache_private, kmflag) != 0)) {
1947 		atomic_inc_64(&cp->cache_alloc_fail);
1948 		btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1949 		if (cp->cache_flags & KMF_DEADBEEF)
1950 			copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1951 		kmem_slab_free(cp, buf);
1952 		return (1);
1953 	}
1954 
1955 	if (cp->cache_flags & KMF_AUDIT) {
1956 		KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1957 	}
1958 
1959 	if ((cp->cache_flags & KMF_LITE) &&
1960 	    !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
1961 		KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
1962 	}
1963 
1964 	return (0);
1965 }
1966 
1967 static int
1968 kmem_cache_free_debug(kmem_cache_t *cp, void *buf, caddr_t caller)
1969 {
1970 	kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1971 	kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
1972 	kmem_slab_t *sp;
1973 
1974 	if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_ALLOC)) {
1975 		if (btp->bt_bxstat == ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
1976 			kmem_error(KMERR_DUPFREE, cp, buf);
1977 			return (-1);
1978 		}
1979 		sp = kmem_findslab(cp, buf);
1980 		if (sp == NULL || sp->slab_cache != cp)
1981 			kmem_error(KMERR_BADADDR, cp, buf);
1982 		else
1983 			kmem_error(KMERR_REDZONE, cp, buf);
1984 		return (-1);
1985 	}
1986 
1987 	btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1988 
1989 	if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
1990 		kmem_error(KMERR_BADBUFCTL, cp, buf);
1991 		return (-1);
1992 	}
1993 
1994 	if (btp->bt_redzone != KMEM_REDZONE_PATTERN) {
1995 		kmem_error(KMERR_REDZONE, cp, buf);
1996 		return (-1);
1997 	}
1998 
1999 	if (cp->cache_flags & KMF_AUDIT) {
2000 		if (cp->cache_flags & KMF_CONTENTS)
2001 			bcp->bc_contents = kmem_log_enter(kmem_content_log,
2002 			    buf, cp->cache_contents);
2003 		KMEM_AUDIT(kmem_transaction_log, cp, bcp);
2004 	}
2005 
2006 	if ((cp->cache_flags & KMF_LITE) &&
2007 	    !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
2008 		KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
2009 	}
2010 
2011 	if (cp->cache_flags & KMF_DEADBEEF) {
2012 		if (cp->cache_flags & KMF_LITE)
2013 			btp->bt_redzone = *(uint64_t *)buf;
2014 		else if (cp->cache_destructor != NULL)
2015 			cp->cache_destructor(buf, cp->cache_private);
2016 
2017 		copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
2018 	}
2019 
2020 	return (0);
2021 }
2022 
2023 /*
2024  * Free each object in magazine mp to cp's slab layer, and free mp itself.
2025  */
2026 static void
2027 kmem_magazine_destroy(kmem_cache_t *cp, kmem_magazine_t *mp, int nrounds)
2028 {
2029 	int round;
2030 
2031 	ASSERT(!list_link_active(&cp->cache_link) ||
2032 	    taskq_member(kmem_taskq, curthread));
2033 
2034 	for (round = 0; round < nrounds; round++) {
2035 		void *buf = mp->mag_round[round];
2036 
2037 		if (cp->cache_flags & KMF_DEADBEEF) {
2038 			if (verify_pattern(KMEM_FREE_PATTERN, buf,
2039 			    cp->cache_verify) != NULL) {
2040 				kmem_error(KMERR_MODIFIED, cp, buf);
2041 				continue;
2042 			}
2043 			if ((cp->cache_flags & KMF_LITE) &&
2044 			    cp->cache_destructor != NULL) {
2045 				kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2046 				*(uint64_t *)buf = btp->bt_redzone;
2047 				cp->cache_destructor(buf, cp->cache_private);
2048 				*(uint64_t *)buf = KMEM_FREE_PATTERN;
2049 			}
2050 		} else if (cp->cache_destructor != NULL) {
2051 			cp->cache_destructor(buf, cp->cache_private);
2052 		}
2053 
2054 		kmem_slab_free(cp, buf);
2055 	}
2056 	ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2057 	kmem_cache_free(cp->cache_magtype->mt_cache, mp);
2058 }
2059 
2060 /*
2061  * Allocate a magazine from the depot.
2062  */
2063 static kmem_magazine_t *
2064 kmem_depot_alloc(kmem_cache_t *cp, kmem_maglist_t *mlp)
2065 {
2066 	kmem_magazine_t *mp;
2067 
2068 	/*
2069 	 * If we can't get the depot lock without contention,
2070 	 * update our contention count.  We use the depot
2071 	 * contention rate to determine whether we need to
2072 	 * increase the magazine size for better scalability.
2073 	 */
2074 	if (!mutex_tryenter(&cp->cache_depot_lock)) {
2075 		mutex_enter(&cp->cache_depot_lock);
2076 		cp->cache_depot_contention++;
2077 	}
2078 
2079 	if ((mp = mlp->ml_list) != NULL) {
2080 		ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2081 		mlp->ml_list = mp->mag_next;
2082 		if (--mlp->ml_total < mlp->ml_min)
2083 			mlp->ml_min = mlp->ml_total;
2084 		mlp->ml_alloc++;
2085 	}
2086 
2087 	mutex_exit(&cp->cache_depot_lock);
2088 
2089 	return (mp);
2090 }
2091 
2092 /*
2093  * Free a magazine to the depot.
2094  */
2095 static void
2096 kmem_depot_free(kmem_cache_t *cp, kmem_maglist_t *mlp, kmem_magazine_t *mp)
2097 {
2098 	mutex_enter(&cp->cache_depot_lock);
2099 	ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2100 	mp->mag_next = mlp->ml_list;
2101 	mlp->ml_list = mp;
2102 	mlp->ml_total++;
2103 	mutex_exit(&cp->cache_depot_lock);
2104 }
2105 
2106 /*
2107  * Update the working set statistics for cp's depot.
2108  */
2109 static void
2110 kmem_depot_ws_update(kmem_cache_t *cp)
2111 {
2112 	mutex_enter(&cp->cache_depot_lock);
2113 	cp->cache_full.ml_reaplimit = cp->cache_full.ml_min;
2114 	cp->cache_full.ml_min = cp->cache_full.ml_total;
2115 	cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_min;
2116 	cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2117 	mutex_exit(&cp->cache_depot_lock);
2118 }
2119 
2120 /*
2121  * Set the working set statistics for cp's depot to zero.  (Everything is
2122  * eligible for reaping.)
2123  */
2124 static void
2125 kmem_depot_ws_zero(kmem_cache_t *cp)
2126 {
2127 	mutex_enter(&cp->cache_depot_lock);
2128 	cp->cache_full.ml_reaplimit = cp->cache_full.ml_total;
2129 	cp->cache_full.ml_min = cp->cache_full.ml_total;
2130 	cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_total;
2131 	cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2132 	mutex_exit(&cp->cache_depot_lock);
2133 }
2134 
2135 /*
2136  * The number of bytes to reap before we call kpreempt(). The default (1MB)
2137  * causes us to preempt reaping up to hundreds of times per second. Using a
2138  * larger value (1GB) causes this to have virtually no effect.
2139  */
2140 size_t kmem_reap_preempt_bytes = 1024 * 1024;
2141 
2142 /*
2143  * Reap all magazines that have fallen out of the depot's working set.
2144  */
2145 static void
2146 kmem_depot_ws_reap(kmem_cache_t *cp)
2147 {
2148 	size_t bytes = 0;
2149 	long reap;
2150 	kmem_magazine_t *mp;
2151 
2152 	ASSERT(!list_link_active(&cp->cache_link) ||
2153 	    taskq_member(kmem_taskq, curthread));
2154 
2155 	reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
2156 	while (reap-- &&
2157 	    (mp = kmem_depot_alloc(cp, &cp->cache_full)) != NULL) {
2158 		kmem_magazine_destroy(cp, mp, cp->cache_magtype->mt_magsize);
2159 		bytes += cp->cache_magtype->mt_magsize * cp->cache_bufsize;
2160 		if (bytes > kmem_reap_preempt_bytes) {
2161 			kpreempt(KPREEMPT_SYNC);
2162 			bytes = 0;
2163 		}
2164 	}
2165 
2166 	reap = MIN(cp->cache_empty.ml_reaplimit, cp->cache_empty.ml_min);
2167 	while (reap-- &&
2168 	    (mp = kmem_depot_alloc(cp, &cp->cache_empty)) != NULL) {
2169 		kmem_magazine_destroy(cp, mp, 0);
2170 		bytes += cp->cache_magtype->mt_magsize * cp->cache_bufsize;
2171 		if (bytes > kmem_reap_preempt_bytes) {
2172 			kpreempt(KPREEMPT_SYNC);
2173 			bytes = 0;
2174 		}
2175 	}
2176 }
2177 
2178 static void
2179 kmem_cpu_reload(kmem_cpu_cache_t *ccp, kmem_magazine_t *mp, int rounds)
2180 {
2181 	ASSERT((ccp->cc_loaded == NULL && ccp->cc_rounds == -1) ||
2182 	    (ccp->cc_loaded && ccp->cc_rounds + rounds == ccp->cc_magsize));
2183 	ASSERT(ccp->cc_magsize > 0);
2184 
2185 	ccp->cc_ploaded = ccp->cc_loaded;
2186 	ccp->cc_prounds = ccp->cc_rounds;
2187 	ccp->cc_loaded = mp;
2188 	ccp->cc_rounds = rounds;
2189 }
2190 
2191 /*
2192  * Intercept kmem alloc/free calls during crash dump in order to avoid
2193  * changing kmem state while memory is being saved to the dump device.
2194  * Otherwise, ::kmem_verify will report "corrupt buffers".  Note that
2195  * there are no locks because only one CPU calls kmem during a crash
2196  * dump. To enable this feature, first create the associated vmem
2197  * arena with VMC_DUMPSAFE.
2198  */
2199 static void *kmem_dump_start;	/* start of pre-reserved heap */
2200 static void *kmem_dump_end;	/* end of heap area */
2201 static void *kmem_dump_curr;	/* current free heap pointer */
2202 static size_t kmem_dump_size;	/* size of heap area */
2203 
2204 /* append to each buf created in the pre-reserved heap */
2205 typedef struct kmem_dumpctl {
2206 	void	*kdc_next;	/* cache dump free list linkage */
2207 } kmem_dumpctl_t;
2208 
2209 #define	KMEM_DUMPCTL(cp, buf)	\
2210 	((kmem_dumpctl_t *)P2ROUNDUP((uintptr_t)(buf) + (cp)->cache_bufsize, \
2211 	    sizeof (void *)))
2212 
2213 /* Keep some simple stats. */
2214 #define	KMEM_DUMP_LOGS	(100)
2215 
2216 typedef struct kmem_dump_log {
2217 	kmem_cache_t	*kdl_cache;
2218 	uint_t		kdl_allocs;		/* # of dump allocations */
2219 	uint_t		kdl_frees;		/* # of dump frees */
2220 	uint_t		kdl_alloc_fails;	/* # of allocation failures */
2221 	uint_t		kdl_free_nondump;	/* # of non-dump frees */
2222 	uint_t		kdl_unsafe;		/* cache was used, but unsafe */
2223 } kmem_dump_log_t;
2224 
2225 static kmem_dump_log_t *kmem_dump_log;
2226 static int kmem_dump_log_idx;
2227 
2228 #define	KDI_LOG(cp, stat) {						\
2229 	kmem_dump_log_t *kdl;						\
2230 	if ((kdl = (kmem_dump_log_t *)((cp)->cache_dumplog)) != NULL) {	\
2231 		kdl->stat++;						\
2232 	} else if (kmem_dump_log_idx < KMEM_DUMP_LOGS) {		\
2233 		kdl = &kmem_dump_log[kmem_dump_log_idx++];		\
2234 		kdl->stat++;						\
2235 		kdl->kdl_cache = (cp);					\
2236 		(cp)->cache_dumplog = kdl;				\
2237 	}								\
2238 }
2239 
2240 /* set non zero for full report */
2241 uint_t kmem_dump_verbose = 0;
2242 
2243 /* stats for overize heap */
2244 uint_t kmem_dump_oversize_allocs = 0;
2245 uint_t kmem_dump_oversize_max = 0;
2246 
2247 static void
2248 kmem_dumppr(char **pp, char *e, const char *format, ...)
2249 {
2250 	char *p = *pp;
2251 
2252 	if (p < e) {
2253 		int n;
2254 		va_list ap;
2255 
2256 		va_start(ap, format);
2257 		n = vsnprintf(p, e - p, format, ap);
2258 		va_end(ap);
2259 		*pp = p + n;
2260 	}
2261 }
2262 
2263 /*
2264  * Called when dumpadm(1M) configures dump parameters.
2265  */
2266 void
2267 kmem_dump_init(size_t size)
2268 {
2269 	if (kmem_dump_start != NULL)
2270 		kmem_free(kmem_dump_start, kmem_dump_size);
2271 
2272 	if (kmem_dump_log == NULL)
2273 		kmem_dump_log = (kmem_dump_log_t *)kmem_zalloc(KMEM_DUMP_LOGS *
2274 		    sizeof (kmem_dump_log_t), KM_SLEEP);
2275 
2276 	kmem_dump_start = kmem_alloc(size, KM_SLEEP);
2277 
2278 	if (kmem_dump_start != NULL) {
2279 		kmem_dump_size = size;
2280 		kmem_dump_curr = kmem_dump_start;
2281 		kmem_dump_end = (void *)((char *)kmem_dump_start + size);
2282 		copy_pattern(KMEM_UNINITIALIZED_PATTERN, kmem_dump_start, size);
2283 	} else {
2284 		kmem_dump_size = 0;
2285 		kmem_dump_curr = NULL;
2286 		kmem_dump_end = NULL;
2287 	}
2288 }
2289 
2290 /*
2291  * Set flag for each kmem_cache_t if is safe to use alternate dump
2292  * memory. Called just before panic crash dump starts. Set the flag
2293  * for the calling CPU.
2294  */
2295 void
2296 kmem_dump_begin(void)
2297 {
2298 	ASSERT(panicstr != NULL);
2299 	if (kmem_dump_start != NULL) {
2300 		kmem_cache_t *cp;
2301 
2302 		for (cp = list_head(&kmem_caches); cp != NULL;
2303 		    cp = list_next(&kmem_caches, cp)) {
2304 			kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2305 
2306 			if (cp->cache_arena->vm_cflags & VMC_DUMPSAFE) {
2307 				cp->cache_flags |= KMF_DUMPDIVERT;
2308 				ccp->cc_flags |= KMF_DUMPDIVERT;
2309 				ccp->cc_dump_rounds = ccp->cc_rounds;
2310 				ccp->cc_dump_prounds = ccp->cc_prounds;
2311 				ccp->cc_rounds = ccp->cc_prounds = -1;
2312 			} else {
2313 				cp->cache_flags |= KMF_DUMPUNSAFE;
2314 				ccp->cc_flags |= KMF_DUMPUNSAFE;
2315 			}
2316 		}
2317 	}
2318 }
2319 
2320 /*
2321  * finished dump intercept
2322  * print any warnings on the console
2323  * return verbose information to dumpsys() in the given buffer
2324  */
2325 size_t
2326 kmem_dump_finish(char *buf, size_t size)
2327 {
2328 	int kdi_idx;
2329 	int kdi_end = kmem_dump_log_idx;
2330 	int percent = 0;
2331 	int header = 0;
2332 	int warn = 0;
2333 	size_t used;
2334 	kmem_cache_t *cp;
2335 	kmem_dump_log_t *kdl;
2336 	char *e = buf + size;
2337 	char *p = buf;
2338 
2339 	if (kmem_dump_size == 0 || kmem_dump_verbose == 0)
2340 		return (0);
2341 
2342 	used = (char *)kmem_dump_curr - (char *)kmem_dump_start;
2343 	percent = (used * 100) / kmem_dump_size;
2344 
2345 	kmem_dumppr(&p, e, "%% heap used,%d\n", percent);
2346 	kmem_dumppr(&p, e, "used bytes,%ld\n", used);
2347 	kmem_dumppr(&p, e, "heap size,%ld\n", kmem_dump_size);
2348 	kmem_dumppr(&p, e, "Oversize allocs,%d\n",
2349 	    kmem_dump_oversize_allocs);
2350 	kmem_dumppr(&p, e, "Oversize max size,%ld\n",
2351 	    kmem_dump_oversize_max);
2352 
2353 	for (kdi_idx = 0; kdi_idx < kdi_end; kdi_idx++) {
2354 		kdl = &kmem_dump_log[kdi_idx];
2355 		cp = kdl->kdl_cache;
2356 		if (cp == NULL)
2357 			break;
2358 		if (kdl->kdl_alloc_fails)
2359 			++warn;
2360 		if (header == 0) {
2361 			kmem_dumppr(&p, e,
2362 			    "Cache Name,Allocs,Frees,Alloc Fails,"
2363 			    "Nondump Frees,Unsafe Allocs/Frees\n");
2364 			header = 1;
2365 		}
2366 		kmem_dumppr(&p, e, "%s,%d,%d,%d,%d,%d\n",
2367 		    cp->cache_name, kdl->kdl_allocs, kdl->kdl_frees,
2368 		    kdl->kdl_alloc_fails, kdl->kdl_free_nondump,
2369 		    kdl->kdl_unsafe);
2370 	}
2371 
2372 	/* return buffer size used */
2373 	if (p < e)
2374 		bzero(p, e - p);
2375 	return (p - buf);
2376 }
2377 
2378 /*
2379  * Allocate a constructed object from alternate dump memory.
2380  */
2381 void *
2382 kmem_cache_alloc_dump(kmem_cache_t *cp, int kmflag)
2383 {
2384 	void *buf;
2385 	void *curr;
2386 	char *bufend;
2387 
2388 	/* return a constructed object */
2389 	if ((buf = cp->cache_dumpfreelist) != NULL) {
2390 		cp->cache_dumpfreelist = KMEM_DUMPCTL(cp, buf)->kdc_next;
2391 		KDI_LOG(cp, kdl_allocs);
2392 		return (buf);
2393 	}
2394 
2395 	/* create a new constructed object */
2396 	curr = kmem_dump_curr;
2397 	buf = (void *)P2ROUNDUP((uintptr_t)curr, cp->cache_align);
2398 	bufend = (char *)KMEM_DUMPCTL(cp, buf) + sizeof (kmem_dumpctl_t);
2399 
2400 	/* hat layer objects cannot cross a page boundary */
2401 	if (cp->cache_align < PAGESIZE) {
2402 		char *page = (char *)P2ROUNDUP((uintptr_t)buf, PAGESIZE);
2403 		if (bufend > page) {
2404 			bufend += page - (char *)buf;
2405 			buf = (void *)page;
2406 		}
2407 	}
2408 
2409 	/* fall back to normal alloc if reserved area is used up */
2410 	if (bufend > (char *)kmem_dump_end) {
2411 		kmem_dump_curr = kmem_dump_end;
2412 		KDI_LOG(cp, kdl_alloc_fails);
2413 		return (NULL);
2414 	}
2415 
2416 	/*
2417 	 * Must advance curr pointer before calling a constructor that
2418 	 * may also allocate memory.
2419 	 */
2420 	kmem_dump_curr = bufend;
2421 
2422 	/* run constructor */
2423 	if (cp->cache_constructor != NULL &&
2424 	    cp->cache_constructor(buf, cp->cache_private, kmflag)
2425 	    != 0) {
2426 #ifdef DEBUG
2427 		printf("name='%s' cache=0x%p: kmem cache constructor failed\n",
2428 		    cp->cache_name, (void *)cp);
2429 #endif
2430 		/* reset curr pointer iff no allocs were done */
2431 		if (kmem_dump_curr == bufend)
2432 			kmem_dump_curr = curr;
2433 
2434 		/* fall back to normal alloc if the constructor fails */
2435 		KDI_LOG(cp, kdl_alloc_fails);
2436 		return (NULL);
2437 	}
2438 
2439 	KDI_LOG(cp, kdl_allocs);
2440 	return (buf);
2441 }
2442 
2443 /*
2444  * Free a constructed object in alternate dump memory.
2445  */
2446 int
2447 kmem_cache_free_dump(kmem_cache_t *cp, void *buf)
2448 {
2449 	/* save constructed buffers for next time */
2450 	if ((char *)buf >= (char *)kmem_dump_start &&
2451 	    (char *)buf < (char *)kmem_dump_end) {
2452 		KMEM_DUMPCTL(cp, buf)->kdc_next = cp->cache_dumpfreelist;
2453 		cp->cache_dumpfreelist = buf;
2454 		KDI_LOG(cp, kdl_frees);
2455 		return (0);
2456 	}
2457 
2458 	/* count all non-dump buf frees */
2459 	KDI_LOG(cp, kdl_free_nondump);
2460 
2461 	/* just drop buffers that were allocated before dump started */
2462 	if (kmem_dump_curr < kmem_dump_end)
2463 		return (0);
2464 
2465 	/* fall back to normal free if reserved area is used up */
2466 	return (1);
2467 }
2468 
2469 /*
2470  * Allocate a constructed object from cache cp.
2471  */
2472 void *
2473 kmem_cache_alloc(kmem_cache_t *cp, int kmflag)
2474 {
2475 	kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2476 	kmem_magazine_t *fmp;
2477 	void *buf;
2478 
2479 	mutex_enter(&ccp->cc_lock);
2480 	for (;;) {
2481 		/*
2482 		 * If there's an object available in the current CPU's
2483 		 * loaded magazine, just take it and return.
2484 		 */
2485 		if (ccp->cc_rounds > 0) {
2486 			buf = ccp->cc_loaded->mag_round[--ccp->cc_rounds];
2487 			ccp->cc_alloc++;
2488 			mutex_exit(&ccp->cc_lock);
2489 			if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPUNSAFE)) {
2490 				if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2491 					ASSERT(!(ccp->cc_flags &
2492 					    KMF_DUMPDIVERT));
2493 					KDI_LOG(cp, kdl_unsafe);
2494 				}
2495 				if ((ccp->cc_flags & KMF_BUFTAG) &&
2496 				    kmem_cache_alloc_debug(cp, buf, kmflag, 0,
2497 				    caller()) != 0) {
2498 					if (kmflag & KM_NOSLEEP)
2499 						return (NULL);
2500 					mutex_enter(&ccp->cc_lock);
2501 					continue;
2502 				}
2503 			}
2504 			return (buf);
2505 		}
2506 
2507 		/*
2508 		 * The loaded magazine is empty.  If the previously loaded
2509 		 * magazine was full, exchange them and try again.
2510 		 */
2511 		if (ccp->cc_prounds > 0) {
2512 			kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2513 			continue;
2514 		}
2515 
2516 		/*
2517 		 * Return an alternate buffer at dump time to preserve
2518 		 * the heap.
2519 		 */
2520 		if (ccp->cc_flags & (KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2521 			if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2522 				ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2523 				/* log it so that we can warn about it */
2524 				KDI_LOG(cp, kdl_unsafe);
2525 			} else {
2526 				if ((buf = kmem_cache_alloc_dump(cp, kmflag)) !=
2527 				    NULL) {
2528 					mutex_exit(&ccp->cc_lock);
2529 					return (buf);
2530 				}
2531 				break;		/* fall back to slab layer */
2532 			}
2533 		}
2534 
2535 		/*
2536 		 * If the magazine layer is disabled, break out now.
2537 		 */
2538 		if (ccp->cc_magsize == 0)
2539 			break;
2540 
2541 		/*
2542 		 * Try to get a full magazine from the depot.
2543 		 */
2544 		fmp = kmem_depot_alloc(cp, &cp->cache_full);
2545 		if (fmp != NULL) {
2546 			if (ccp->cc_ploaded != NULL)
2547 				kmem_depot_free(cp, &cp->cache_empty,
2548 				    ccp->cc_ploaded);
2549 			kmem_cpu_reload(ccp, fmp, ccp->cc_magsize);
2550 			continue;
2551 		}
2552 
2553 		/*
2554 		 * There are no full magazines in the depot,
2555 		 * so fall through to the slab layer.
2556 		 */
2557 		break;
2558 	}
2559 	mutex_exit(&ccp->cc_lock);
2560 
2561 	/*
2562 	 * We couldn't allocate a constructed object from the magazine layer,
2563 	 * so get a raw buffer from the slab layer and apply its constructor.
2564 	 */
2565 	buf = kmem_slab_alloc(cp, kmflag);
2566 
2567 	if (buf == NULL)
2568 		return (NULL);
2569 
2570 	if (cp->cache_flags & KMF_BUFTAG) {
2571 		/*
2572 		 * Make kmem_cache_alloc_debug() apply the constructor for us.
2573 		 */
2574 		int rc = kmem_cache_alloc_debug(cp, buf, kmflag, 1, caller());
2575 		if (rc != 0) {
2576 			if (kmflag & KM_NOSLEEP)
2577 				return (NULL);
2578 			/*
2579 			 * kmem_cache_alloc_debug() detected corruption
2580 			 * but didn't panic (kmem_panic <= 0). We should not be
2581 			 * here because the constructor failed (indicated by a
2582 			 * return code of 1). Try again.
2583 			 */
2584 			ASSERT(rc == -1);
2585 			return (kmem_cache_alloc(cp, kmflag));
2586 		}
2587 		return (buf);
2588 	}
2589 
2590 	if (cp->cache_constructor != NULL &&
2591 	    cp->cache_constructor(buf, cp->cache_private, kmflag) != 0) {
2592 		atomic_inc_64(&cp->cache_alloc_fail);
2593 		kmem_slab_free(cp, buf);
2594 		return (NULL);
2595 	}
2596 
2597 	return (buf);
2598 }
2599 
2600 /*
2601  * The freed argument tells whether or not kmem_cache_free_debug() has already
2602  * been called so that we can avoid the duplicate free error. For example, a
2603  * buffer on a magazine has already been freed by the client but is still
2604  * constructed.
2605  */
2606 static void
2607 kmem_slab_free_constructed(kmem_cache_t *cp, void *buf, boolean_t freed)
2608 {
2609 	if (!freed && (cp->cache_flags & KMF_BUFTAG))
2610 		if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2611 			return;
2612 
2613 	/*
2614 	 * Note that if KMF_DEADBEEF is in effect and KMF_LITE is not,
2615 	 * kmem_cache_free_debug() will have already applied the destructor.
2616 	 */
2617 	if ((cp->cache_flags & (KMF_DEADBEEF | KMF_LITE)) != KMF_DEADBEEF &&
2618 	    cp->cache_destructor != NULL) {
2619 		if (cp->cache_flags & KMF_DEADBEEF) {	/* KMF_LITE implied */
2620 			kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2621 			*(uint64_t *)buf = btp->bt_redzone;
2622 			cp->cache_destructor(buf, cp->cache_private);
2623 			*(uint64_t *)buf = KMEM_FREE_PATTERN;
2624 		} else {
2625 			cp->cache_destructor(buf, cp->cache_private);
2626 		}
2627 	}
2628 
2629 	kmem_slab_free(cp, buf);
2630 }
2631 
2632 /*
2633  * Used when there's no room to free a buffer to the per-CPU cache.
2634  * Drops and re-acquires &ccp->cc_lock, and returns non-zero if the
2635  * caller should try freeing to the per-CPU cache again.
2636  * Note that we don't directly install the magazine in the cpu cache,
2637  * since its state may have changed wildly while the lock was dropped.
2638  */
2639 static int
2640 kmem_cpucache_magazine_alloc(kmem_cpu_cache_t *ccp, kmem_cache_t *cp)
2641 {
2642 	kmem_magazine_t *emp;
2643 	kmem_magtype_t *mtp;
2644 
2645 	ASSERT(MUTEX_HELD(&ccp->cc_lock));
2646 	ASSERT(((uint_t)ccp->cc_rounds == ccp->cc_magsize ||
2647 	    ((uint_t)ccp->cc_rounds == -1)) &&
2648 	    ((uint_t)ccp->cc_prounds == ccp->cc_magsize ||
2649 	    ((uint_t)ccp->cc_prounds == -1)));
2650 
2651 	emp = kmem_depot_alloc(cp, &cp->cache_empty);
2652 	if (emp != NULL) {
2653 		if (ccp->cc_ploaded != NULL)
2654 			kmem_depot_free(cp, &cp->cache_full,
2655 			    ccp->cc_ploaded);
2656 		kmem_cpu_reload(ccp, emp, 0);
2657 		return (1);
2658 	}
2659 	/*
2660 	 * There are no empty magazines in the depot,
2661 	 * so try to allocate a new one.  We must drop all locks
2662 	 * across kmem_cache_alloc() because lower layers may
2663 	 * attempt to allocate from this cache.
2664 	 */
2665 	mtp = cp->cache_magtype;
2666 	mutex_exit(&ccp->cc_lock);
2667 	emp = kmem_cache_alloc(mtp->mt_cache, KM_NOSLEEP);
2668 	mutex_enter(&ccp->cc_lock);
2669 
2670 	if (emp != NULL) {
2671 		/*
2672 		 * We successfully allocated an empty magazine.
2673 		 * However, we had to drop ccp->cc_lock to do it,
2674 		 * so the cache's magazine size may have changed.
2675 		 * If so, free the magazine and try again.
2676 		 */
2677 		if (ccp->cc_magsize != mtp->mt_magsize) {
2678 			mutex_exit(&ccp->cc_lock);
2679 			kmem_cache_free(mtp->mt_cache, emp);
2680 			mutex_enter(&ccp->cc_lock);
2681 			return (1);
2682 		}
2683 
2684 		/*
2685 		 * We got a magazine of the right size.  Add it to
2686 		 * the depot and try the whole dance again.
2687 		 */
2688 		kmem_depot_free(cp, &cp->cache_empty, emp);
2689 		return (1);
2690 	}
2691 
2692 	/*
2693 	 * We couldn't allocate an empty magazine,
2694 	 * so fall through to the slab layer.
2695 	 */
2696 	return (0);
2697 }
2698 
2699 /*
2700  * Free a constructed object to cache cp.
2701  */
2702 void
2703 kmem_cache_free(kmem_cache_t *cp, void *buf)
2704 {
2705 	kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2706 
2707 	/*
2708 	 * The client must not free either of the buffers passed to the move
2709 	 * callback function.
2710 	 */
2711 	ASSERT(cp->cache_defrag == NULL ||
2712 	    cp->cache_defrag->kmd_thread != curthread ||
2713 	    (buf != cp->cache_defrag->kmd_from_buf &&
2714 	    buf != cp->cache_defrag->kmd_to_buf));
2715 
2716 	if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2717 		if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2718 			ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2719 			/* log it so that we can warn about it */
2720 			KDI_LOG(cp, kdl_unsafe);
2721 		} else if (KMEM_DUMPCC(ccp) && !kmem_cache_free_dump(cp, buf)) {
2722 			return;
2723 		}
2724 		if (ccp->cc_flags & KMF_BUFTAG) {
2725 			if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2726 				return;
2727 		}
2728 	}
2729 
2730 	mutex_enter(&ccp->cc_lock);
2731 	/*
2732 	 * Any changes to this logic should be reflected in kmem_slab_prefill()
2733 	 */
2734 	for (;;) {
2735 		/*
2736 		 * If there's a slot available in the current CPU's
2737 		 * loaded magazine, just put the object there and return.
2738 		 */
2739 		if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2740 			ccp->cc_loaded->mag_round[ccp->cc_rounds++] = buf;
2741 			ccp->cc_free++;
2742 			mutex_exit(&ccp->cc_lock);
2743 			return;
2744 		}
2745 
2746 		/*
2747 		 * The loaded magazine is full.  If the previously loaded
2748 		 * magazine was empty, exchange them and try again.
2749 		 */
2750 		if (ccp->cc_prounds == 0) {
2751 			kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2752 			continue;
2753 		}
2754 
2755 		/*
2756 		 * If the magazine layer is disabled, break out now.
2757 		 */
2758 		if (ccp->cc_magsize == 0)
2759 			break;
2760 
2761 		if (!kmem_cpucache_magazine_alloc(ccp, cp)) {
2762 			/*
2763 			 * We couldn't free our constructed object to the
2764 			 * magazine layer, so apply its destructor and free it
2765 			 * to the slab layer.
2766 			 */
2767 			break;
2768 		}
2769 	}
2770 	mutex_exit(&ccp->cc_lock);
2771 	kmem_slab_free_constructed(cp, buf, B_TRUE);
2772 }
2773 
2774 static void
2775 kmem_slab_prefill(kmem_cache_t *cp, kmem_slab_t *sp)
2776 {
2777 	kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2778 	int cache_flags = cp->cache_flags;
2779 
2780 	kmem_bufctl_t *next, *head;
2781 	size_t nbufs;
2782 
2783 	/*
2784 	 * Completely allocate the newly created slab and put the pre-allocated
2785 	 * buffers in magazines. Any of the buffers that cannot be put in
2786 	 * magazines must be returned to the slab.
2787 	 */
2788 	ASSERT(MUTEX_HELD(&cp->cache_lock));
2789 	ASSERT((cache_flags & (KMF_PREFILL|KMF_BUFTAG)) == KMF_PREFILL);
2790 	ASSERT(cp->cache_constructor == NULL);
2791 	ASSERT(sp->slab_cache == cp);
2792 	ASSERT(sp->slab_refcnt == 1);
2793 	ASSERT(sp->slab_head != NULL && sp->slab_chunks > sp->slab_refcnt);
2794 	ASSERT(avl_find(&cp->cache_partial_slabs, sp, NULL) == NULL);
2795 
2796 	head = sp->slab_head;
2797 	nbufs = (sp->slab_chunks - sp->slab_refcnt);
2798 	sp->slab_head = NULL;
2799 	sp->slab_refcnt += nbufs;
2800 	cp->cache_bufslab -= nbufs;
2801 	cp->cache_slab_alloc += nbufs;
2802 	list_insert_head(&cp->cache_complete_slabs, sp);
2803 	cp->cache_complete_slab_count++;
2804 	mutex_exit(&cp->cache_lock);
2805 	mutex_enter(&ccp->cc_lock);
2806 
2807 	while (head != NULL) {
2808 		void *buf = KMEM_BUF(cp, head);
2809 		/*
2810 		 * If there's a slot available in the current CPU's
2811 		 * loaded magazine, just put the object there and
2812 		 * continue.
2813 		 */
2814 		if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2815 			ccp->cc_loaded->mag_round[ccp->cc_rounds++] =
2816 			    buf;
2817 			ccp->cc_free++;
2818 			nbufs--;
2819 			head = head->bc_next;
2820 			continue;
2821 		}
2822 
2823 		/*
2824 		 * The loaded magazine is full.  If the previously
2825 		 * loaded magazine was empty, exchange them and try
2826 		 * again.
2827 		 */
2828 		if (ccp->cc_prounds == 0) {
2829 			kmem_cpu_reload(ccp, ccp->cc_ploaded,
2830 			    ccp->cc_prounds);
2831 			continue;
2832 		}
2833 
2834 		/*
2835 		 * If the magazine layer is disabled, break out now.
2836 		 */
2837 
2838 		if (ccp->cc_magsize == 0) {
2839 			break;
2840 		}
2841 
2842 		if (!kmem_cpucache_magazine_alloc(ccp, cp))
2843 			break;
2844 	}
2845 	mutex_exit(&ccp->cc_lock);
2846 	if (nbufs != 0) {
2847 		ASSERT(head != NULL);
2848 
2849 		/*
2850 		 * If there was a failure, return remaining objects to
2851 		 * the slab
2852 		 */
2853 		while (head != NULL) {
2854 			ASSERT(nbufs != 0);
2855 			next = head->bc_next;
2856 			head->bc_next = NULL;
2857 			kmem_slab_free(cp, KMEM_BUF(cp, head));
2858 			head = next;
2859 			nbufs--;
2860 		}
2861 	}
2862 	ASSERT(head == NULL);
2863 	ASSERT(nbufs == 0);
2864 	mutex_enter(&cp->cache_lock);
2865 }
2866 
2867 void *
2868 kmem_zalloc(size_t size, int kmflag)
2869 {
2870 	size_t index;
2871 	void *buf;
2872 
2873 	if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2874 		kmem_cache_t *cp = kmem_alloc_table[index];
2875 		buf = kmem_cache_alloc(cp, kmflag);
2876 		if (buf != NULL) {
2877 			if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2878 				kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2879 				((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2880 				((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2881 
2882 				if (cp->cache_flags & KMF_LITE) {
2883 					KMEM_BUFTAG_LITE_ENTER(btp,
2884 					    kmem_lite_count, caller());
2885 				}
2886 			}
2887 			bzero(buf, size);
2888 		}
2889 	} else {
2890 		buf = kmem_alloc(size, kmflag);
2891 		if (buf != NULL)
2892 			bzero(buf, size);
2893 	}
2894 	return (buf);
2895 }
2896 
2897 void *
2898 kmem_alloc(size_t size, int kmflag)
2899 {
2900 	size_t index;
2901 	kmem_cache_t *cp;
2902 	void *buf;
2903 
2904 	if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2905 		cp = kmem_alloc_table[index];
2906 		/* fall through to kmem_cache_alloc() */
2907 
2908 	} else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2909 	    kmem_big_alloc_table_max) {
2910 		cp = kmem_big_alloc_table[index];
2911 		/* fall through to kmem_cache_alloc() */
2912 
2913 	} else {
2914 		if (size == 0)
2915 			return (NULL);
2916 
2917 		buf = vmem_alloc(kmem_oversize_arena, size,
2918 		    kmflag & KM_VMFLAGS);
2919 		if (buf == NULL)
2920 			kmem_log_event(kmem_failure_log, NULL, NULL,
2921 			    (void *)size);
2922 		else if (KMEM_DUMP(kmem_slab_cache)) {
2923 			/* stats for dump intercept */
2924 			kmem_dump_oversize_allocs++;
2925 			if (size > kmem_dump_oversize_max)
2926 				kmem_dump_oversize_max = size;
2927 		}
2928 		return (buf);
2929 	}
2930 
2931 	buf = kmem_cache_alloc(cp, kmflag);
2932 	if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp) && buf != NULL) {
2933 		kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2934 		((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2935 		((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2936 
2937 		if (cp->cache_flags & KMF_LITE) {
2938 			KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller());
2939 		}
2940 	}
2941 	return (buf);
2942 }
2943 
2944 void
2945 kmem_free(void *buf, size_t size)
2946 {
2947 	size_t index;
2948 	kmem_cache_t *cp;
2949 
2950 	if ((index = (size - 1) >> KMEM_ALIGN_SHIFT) < KMEM_ALLOC_TABLE_MAX) {
2951 		cp = kmem_alloc_table[index];
2952 		/* fall through to kmem_cache_free() */
2953 
2954 	} else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2955 	    kmem_big_alloc_table_max) {
2956 		cp = kmem_big_alloc_table[index];
2957 		/* fall through to kmem_cache_free() */
2958 
2959 	} else {
2960 		EQUIV(buf == NULL, size == 0);
2961 		if (buf == NULL && size == 0)
2962 			return;
2963 		vmem_free(kmem_oversize_arena, buf, size);
2964 		return;
2965 	}
2966 
2967 	if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2968 		kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2969 		uint32_t *ip = (uint32_t *)btp;
2970 		if (ip[1] != KMEM_SIZE_ENCODE(size)) {
2971 			if (*(uint64_t *)buf == KMEM_FREE_PATTERN) {
2972 				kmem_error(KMERR_DUPFREE, cp, buf);
2973 				return;
2974 			}
2975 			if (KMEM_SIZE_VALID(ip[1])) {
2976 				ip[0] = KMEM_SIZE_ENCODE(size);
2977 				kmem_error(KMERR_BADSIZE, cp, buf);
2978 			} else {
2979 				kmem_error(KMERR_REDZONE, cp, buf);
2980 			}
2981 			return;
2982 		}
2983 		if (((uint8_t *)buf)[size] != KMEM_REDZONE_BYTE) {
2984 			kmem_error(KMERR_REDZONE, cp, buf);
2985 			return;
2986 		}
2987 		btp->bt_redzone = KMEM_REDZONE_PATTERN;
2988 		if (cp->cache_flags & KMF_LITE) {
2989 			KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count,
2990 			    caller());
2991 		}
2992 	}
2993 	kmem_cache_free(cp, buf);
2994 }
2995 
2996 void *
2997 kmem_firewall_va_alloc(vmem_t *vmp, size_t size, int vmflag)
2998 {
2999 	size_t realsize = size + vmp->vm_quantum;
3000 	void *addr;
3001 
3002 	/*
3003 	 * Annoying edge case: if 'size' is just shy of ULONG_MAX, adding
3004 	 * vm_quantum will cause integer wraparound.  Check for this, and
3005 	 * blow off the firewall page in this case.  Note that such a
3006 	 * giant allocation (the entire kernel address space) can never
3007 	 * be satisfied, so it will either fail immediately (VM_NOSLEEP)
3008 	 * or sleep forever (VM_SLEEP).  Thus, there is no need for a
3009 	 * corresponding check in kmem_firewall_va_free().
3010 	 */
3011 	if (realsize < size)
3012 		realsize = size;
3013 
3014 	/*
3015 	 * While boot still owns resource management, make sure that this
3016 	 * redzone virtual address allocation is properly accounted for in
3017 	 * OBPs "virtual-memory" "available" lists because we're
3018 	 * effectively claiming them for a red zone.  If we don't do this,
3019 	 * the available lists become too fragmented and too large for the
3020 	 * current boot/kernel memory list interface.
3021 	 */
3022 	addr = vmem_alloc(vmp, realsize, vmflag | VM_NEXTFIT);
3023 
3024 	if (addr != NULL && kvseg.s_base == NULL && realsize != size)
3025 		(void) boot_virt_alloc((char *)addr + size, vmp->vm_quantum);
3026 
3027 	return (addr);
3028 }
3029 
3030 void
3031 kmem_firewall_va_free(vmem_t *vmp, void *addr, size_t size)
3032 {
3033 	ASSERT((kvseg.s_base == NULL ?
3034 	    va_to_pfn((char *)addr + size) :
3035 	    hat_getpfnum(kas.a_hat, (caddr_t)addr + size)) == PFN_INVALID);
3036 
3037 	vmem_free(vmp, addr, size + vmp->vm_quantum);
3038 }
3039 
3040 /*
3041  * Try to allocate at least `size' bytes of memory without sleeping or
3042  * panicking. Return actual allocated size in `asize'. If allocation failed,
3043  * try final allocation with sleep or panic allowed.
3044  */
3045 void *
3046 kmem_alloc_tryhard(size_t size, size_t *asize, int kmflag)
3047 {
3048 	void *p;
3049 
3050 	*asize = P2ROUNDUP(size, KMEM_ALIGN);
3051 	do {
3052 		p = kmem_alloc(*asize, (kmflag | KM_NOSLEEP) & ~KM_PANIC);
3053 		if (p != NULL)
3054 			return (p);
3055 		*asize += KMEM_ALIGN;
3056 	} while (*asize <= PAGESIZE);
3057 
3058 	*asize = P2ROUNDUP(size, KMEM_ALIGN);
3059 	return (kmem_alloc(*asize, kmflag));
3060 }
3061 
3062 /*
3063  * Reclaim all unused memory from a cache.
3064  */
3065 static void
3066 kmem_cache_reap(kmem_cache_t *cp)
3067 {
3068 	ASSERT(taskq_member(kmem_taskq, curthread));
3069 	cp->cache_reap++;
3070 
3071 	/*
3072 	 * Ask the cache's owner to free some memory if possible.
3073 	 * The idea is to handle things like the inode cache, which
3074 	 * typically sits on a bunch of memory that it doesn't truly
3075 	 * *need*.  Reclaim policy is entirely up to the owner; this
3076 	 * callback is just an advisory plea for help.
3077 	 */
3078 	if (cp->cache_reclaim != NULL) {
3079 		long delta;
3080 
3081 		/*
3082 		 * Reclaimed memory should be reapable (not included in the
3083 		 * depot's working set).
3084 		 */
3085 		delta = cp->cache_full.ml_total;
3086 		cp->cache_reclaim(cp->cache_private);
3087 		delta = cp->cache_full.ml_total - delta;
3088 		if (delta > 0) {
3089 			mutex_enter(&cp->cache_depot_lock);
3090 			cp->cache_full.ml_reaplimit += delta;
3091 			cp->cache_full.ml_min += delta;
3092 			mutex_exit(&cp->cache_depot_lock);
3093 		}
3094 	}
3095 
3096 	kmem_depot_ws_reap(cp);
3097 
3098 	if (cp->cache_defrag != NULL && !kmem_move_noreap) {
3099 		kmem_cache_defrag(cp);
3100 	}
3101 }
3102 
3103 static void
3104 kmem_reap_timeout(void *flag_arg)
3105 {
3106 	uint32_t *flag = (uint32_t *)flag_arg;
3107 
3108 	ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3109 	*flag = 0;
3110 }
3111 
3112 static void
3113 kmem_reap_done(void *flag)
3114 {
3115 	if (!callout_init_done) {
3116 		/* can't schedule a timeout at this point */
3117 		kmem_reap_timeout(flag);
3118 	} else {
3119 		(void) timeout(kmem_reap_timeout, flag, kmem_reap_interval);
3120 	}
3121 }
3122 
3123 static void
3124 kmem_reap_start(void *flag)
3125 {
3126 	ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3127 
3128 	if (flag == &kmem_reaping) {
3129 		kmem_cache_applyall(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3130 		/*
3131 		 * if we have segkp under heap, reap segkp cache.
3132 		 */
3133 		if (segkp_fromheap)
3134 			segkp_cache_free();
3135 	}
3136 	else
3137 		kmem_cache_applyall_id(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3138 
3139 	/*
3140 	 * We use taskq_dispatch() to schedule a timeout to clear
3141 	 * the flag so that kmem_reap() becomes self-throttling:
3142 	 * we won't reap again until the current reap completes *and*
3143 	 * at least kmem_reap_interval ticks have elapsed.
3144 	 */
3145 	if (!taskq_dispatch(kmem_taskq, kmem_reap_done, flag, TQ_NOSLEEP))
3146 		kmem_reap_done(flag);
3147 }
3148 
3149 static void
3150 kmem_reap_common(void *flag_arg)
3151 {
3152 	uint32_t *flag = (uint32_t *)flag_arg;
3153 
3154 	if (MUTEX_HELD(&kmem_cache_lock) || kmem_taskq == NULL ||
3155 	    atomic_cas_32(flag, 0, 1) != 0)
3156 		return;
3157 
3158 	/*
3159 	 * It may not be kosher to do memory allocation when a reap is called
3160 	 * (for example, if vmem_populate() is in the call chain).  So we
3161 	 * start the reap going with a TQ_NOALLOC dispatch.  If the dispatch
3162 	 * fails, we reset the flag, and the next reap will try again.
3163 	 */
3164 	if (!taskq_dispatch(kmem_taskq, kmem_reap_start, flag, TQ_NOALLOC))
3165 		*flag = 0;
3166 }
3167 
3168 /*
3169  * Reclaim all unused memory from all caches.  Called from the VM system
3170  * when memory gets tight.
3171  */
3172 void
3173 kmem_reap(void)
3174 {
3175 	kmem_reap_common(&kmem_reaping);
3176 }
3177 
3178 /*
3179  * Reclaim all unused memory from identifier arenas, called when a vmem
3180  * arena not back by memory is exhausted.  Since reaping memory-backed caches
3181  * cannot help with identifier exhaustion, we avoid both a large amount of
3182  * work and unwanted side-effects from reclaim callbacks.
3183  */
3184 void
3185 kmem_reap_idspace(void)
3186 {
3187 	kmem_reap_common(&kmem_reaping_idspace);
3188 }
3189 
3190 /*
3191  * Purge all magazines from a cache and set its magazine limit to zero.
3192  * All calls are serialized by the kmem_taskq lock, except for the final
3193  * call from kmem_cache_destroy().
3194  */
3195 static void
3196 kmem_cache_magazine_purge(kmem_cache_t *cp)
3197 {
3198 	kmem_cpu_cache_t *ccp;
3199 	kmem_magazine_t *mp, *pmp;
3200 	int rounds, prounds, cpu_seqid;
3201 
3202 	ASSERT(!list_link_active(&cp->cache_link) ||
3203 	    taskq_member(kmem_taskq, curthread));
3204 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
3205 
3206 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3207 		ccp = &cp->cache_cpu[cpu_seqid];
3208 
3209 		mutex_enter(&ccp->cc_lock);
3210 		mp = ccp->cc_loaded;
3211 		pmp = ccp->cc_ploaded;
3212 		rounds = ccp->cc_rounds;
3213 		prounds = ccp->cc_prounds;
3214 		ccp->cc_loaded = NULL;
3215 		ccp->cc_ploaded = NULL;
3216 		ccp->cc_rounds = -1;
3217 		ccp->cc_prounds = -1;
3218 		ccp->cc_magsize = 0;
3219 		mutex_exit(&ccp->cc_lock);
3220 
3221 		if (mp)
3222 			kmem_magazine_destroy(cp, mp, rounds);
3223 		if (pmp)
3224 			kmem_magazine_destroy(cp, pmp, prounds);
3225 	}
3226 
3227 	kmem_depot_ws_zero(cp);
3228 	kmem_depot_ws_reap(cp);
3229 }
3230 
3231 /*
3232  * Enable per-cpu magazines on a cache.
3233  */
3234 static void
3235 kmem_cache_magazine_enable(kmem_cache_t *cp)
3236 {
3237 	int cpu_seqid;
3238 
3239 	if (cp->cache_flags & KMF_NOMAGAZINE)
3240 		return;
3241 
3242 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3243 		kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3244 		mutex_enter(&ccp->cc_lock);
3245 		ccp->cc_magsize = cp->cache_magtype->mt_magsize;
3246 		mutex_exit(&ccp->cc_lock);
3247 	}
3248 
3249 }
3250 
3251 /*
3252  * Reap (almost) everything right now.
3253  */
3254 void
3255 kmem_cache_reap_now(kmem_cache_t *cp)
3256 {
3257 	ASSERT(list_link_active(&cp->cache_link));
3258 
3259 	kmem_depot_ws_zero(cp);
3260 
3261 	(void) taskq_dispatch(kmem_taskq,
3262 	    (task_func_t *)kmem_depot_ws_reap, cp, TQ_SLEEP);
3263 	taskq_wait(kmem_taskq);
3264 }
3265 
3266 /*
3267  * Recompute a cache's magazine size.  The trade-off is that larger magazines
3268  * provide a higher transfer rate with the depot, while smaller magazines
3269  * reduce memory consumption.  Magazine resizing is an expensive operation;
3270  * it should not be done frequently.
3271  *
3272  * Changes to the magazine size are serialized by the kmem_taskq lock.
3273  *
3274  * Note: at present this only grows the magazine size.  It might be useful
3275  * to allow shrinkage too.
3276  */
3277 static void
3278 kmem_cache_magazine_resize(kmem_cache_t *cp)
3279 {
3280 	kmem_magtype_t *mtp = cp->cache_magtype;
3281 
3282 	ASSERT(taskq_member(kmem_taskq, curthread));
3283 
3284 	if (cp->cache_chunksize < mtp->mt_maxbuf) {
3285 		kmem_cache_magazine_purge(cp);
3286 		mutex_enter(&cp->cache_depot_lock);
3287 		cp->cache_magtype = ++mtp;
3288 		cp->cache_depot_contention_prev =
3289 		    cp->cache_depot_contention + INT_MAX;
3290 		mutex_exit(&cp->cache_depot_lock);
3291 		kmem_cache_magazine_enable(cp);
3292 	}
3293 }
3294 
3295 /*
3296  * Rescale a cache's hash table, so that the table size is roughly the
3297  * cache size.  We want the average lookup time to be extremely small.
3298  */
3299 static void
3300 kmem_hash_rescale(kmem_cache_t *cp)
3301 {
3302 	kmem_bufctl_t **old_table, **new_table, *bcp;
3303 	size_t old_size, new_size, h;
3304 
3305 	ASSERT(taskq_member(kmem_taskq, curthread));
3306 
3307 	new_size = MAX(KMEM_HASH_INITIAL,
3308 	    1 << (highbit(3 * cp->cache_buftotal + 4) - 2));
3309 	old_size = cp->cache_hash_mask + 1;
3310 
3311 	if ((old_size >> 1) <= new_size && new_size <= (old_size << 1))
3312 		return;
3313 
3314 	new_table = vmem_alloc(kmem_hash_arena, new_size * sizeof (void *),
3315 	    VM_NOSLEEP);
3316 	if (new_table == NULL)
3317 		return;
3318 	bzero(new_table, new_size * sizeof (void *));
3319 
3320 	mutex_enter(&cp->cache_lock);
3321 
3322 	old_size = cp->cache_hash_mask + 1;
3323 	old_table = cp->cache_hash_table;
3324 
3325 	cp->cache_hash_mask = new_size - 1;
3326 	cp->cache_hash_table = new_table;
3327 	cp->cache_rescale++;
3328 
3329 	for (h = 0; h < old_size; h++) {
3330 		bcp = old_table[h];
3331 		while (bcp != NULL) {
3332 			void *addr = bcp->bc_addr;
3333 			kmem_bufctl_t *next_bcp = bcp->bc_next;
3334 			kmem_bufctl_t **hash_bucket = KMEM_HASH(cp, addr);
3335 			bcp->bc_next = *hash_bucket;
3336 			*hash_bucket = bcp;
3337 			bcp = next_bcp;
3338 		}
3339 	}
3340 
3341 	mutex_exit(&cp->cache_lock);
3342 
3343 	vmem_free(kmem_hash_arena, old_table, old_size * sizeof (void *));
3344 }
3345 
3346 /*
3347  * Perform periodic maintenance on a cache: hash rescaling, depot working-set
3348  * update, magazine resizing, and slab consolidation.
3349  */
3350 static void
3351 kmem_cache_update(kmem_cache_t *cp)
3352 {
3353 	int need_hash_rescale = 0;
3354 	int need_magazine_resize = 0;
3355 
3356 	ASSERT(MUTEX_HELD(&kmem_cache_lock));
3357 
3358 	/*
3359 	 * If the cache has become much larger or smaller than its hash table,
3360 	 * fire off a request to rescale the hash table.
3361 	 */
3362 	mutex_enter(&cp->cache_lock);
3363 
3364 	if ((cp->cache_flags & KMF_HASH) &&
3365 	    (cp->cache_buftotal > (cp->cache_hash_mask << 1) ||
3366 	    (cp->cache_buftotal < (cp->cache_hash_mask >> 1) &&
3367 	    cp->cache_hash_mask > KMEM_HASH_INITIAL)))
3368 		need_hash_rescale = 1;
3369 
3370 	mutex_exit(&cp->cache_lock);
3371 
3372 	/*
3373 	 * Update the depot working set statistics.
3374 	 */
3375 	kmem_depot_ws_update(cp);
3376 
3377 	/*
3378 	 * If there's a lot of contention in the depot,
3379 	 * increase the magazine size.
3380 	 */
3381 	mutex_enter(&cp->cache_depot_lock);
3382 
3383 	if (cp->cache_chunksize < cp->cache_magtype->mt_maxbuf &&
3384 	    (int)(cp->cache_depot_contention -
3385 	    cp->cache_depot_contention_prev) > kmem_depot_contention)
3386 		need_magazine_resize = 1;
3387 
3388 	cp->cache_depot_contention_prev = cp->cache_depot_contention;
3389 
3390 	mutex_exit(&cp->cache_depot_lock);
3391 
3392 	if (need_hash_rescale)
3393 		(void) taskq_dispatch(kmem_taskq,
3394 		    (task_func_t *)kmem_hash_rescale, cp, TQ_NOSLEEP);
3395 
3396 	if (need_magazine_resize)
3397 		(void) taskq_dispatch(kmem_taskq,
3398 		    (task_func_t *)kmem_cache_magazine_resize, cp, TQ_NOSLEEP);
3399 
3400 	if (cp->cache_defrag != NULL)
3401 		(void) taskq_dispatch(kmem_taskq,
3402 		    (task_func_t *)kmem_cache_scan, cp, TQ_NOSLEEP);
3403 }
3404 
3405 static void kmem_update(void *);
3406 
3407 static void
3408 kmem_update_timeout(void *dummy)
3409 {
3410 	(void) timeout(kmem_update, dummy, kmem_reap_interval);
3411 }
3412 
3413 static void
3414 kmem_update(void *dummy)
3415 {
3416 	kmem_cache_applyall(kmem_cache_update, NULL, TQ_NOSLEEP);
3417 
3418 	/*
3419 	 * We use taskq_dispatch() to reschedule the timeout so that
3420 	 * kmem_update() becomes self-throttling: it won't schedule
3421 	 * new tasks until all previous tasks have completed.
3422 	 */
3423 	if (!taskq_dispatch(kmem_taskq, kmem_update_timeout, dummy, TQ_NOSLEEP))
3424 		kmem_update_timeout(NULL);
3425 }
3426 
3427 static int
3428 kmem_cache_kstat_update(kstat_t *ksp, int rw)
3429 {
3430 	struct kmem_cache_kstat *kmcp = &kmem_cache_kstat;
3431 	kmem_cache_t *cp = ksp->ks_private;
3432 	uint64_t cpu_buf_avail;
3433 	uint64_t buf_avail = 0;
3434 	int cpu_seqid;
3435 	long reap;
3436 
3437 	ASSERT(MUTEX_HELD(&kmem_cache_kstat_lock));
3438 
3439 	if (rw == KSTAT_WRITE)
3440 		return (EACCES);
3441 
3442 	mutex_enter(&cp->cache_lock);
3443 
3444 	kmcp->kmc_alloc_fail.value.ui64		= cp->cache_alloc_fail;
3445 	kmcp->kmc_alloc.value.ui64		= cp->cache_slab_alloc;
3446 	kmcp->kmc_free.value.ui64		= cp->cache_slab_free;
3447 	kmcp->kmc_slab_alloc.value.ui64		= cp->cache_slab_alloc;
3448 	kmcp->kmc_slab_free.value.ui64		= cp->cache_slab_free;
3449 
3450 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3451 		kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3452 
3453 		mutex_enter(&ccp->cc_lock);
3454 
3455 		cpu_buf_avail = 0;
3456 		if (ccp->cc_rounds > 0)
3457 			cpu_buf_avail += ccp->cc_rounds;
3458 		if (ccp->cc_prounds > 0)
3459 			cpu_buf_avail += ccp->cc_prounds;
3460 
3461 		kmcp->kmc_alloc.value.ui64	+= ccp->cc_alloc;
3462 		kmcp->kmc_free.value.ui64	+= ccp->cc_free;
3463 		buf_avail			+= cpu_buf_avail;
3464 
3465 		mutex_exit(&ccp->cc_lock);
3466 	}
3467 
3468 	mutex_enter(&cp->cache_depot_lock);
3469 
3470 	kmcp->kmc_depot_alloc.value.ui64	= cp->cache_full.ml_alloc;
3471 	kmcp->kmc_depot_free.value.ui64		= cp->cache_empty.ml_alloc;
3472 	kmcp->kmc_depot_contention.value.ui64	= cp->cache_depot_contention;
3473 	kmcp->kmc_full_magazines.value.ui64	= cp->cache_full.ml_total;
3474 	kmcp->kmc_empty_magazines.value.ui64	= cp->cache_empty.ml_total;
3475 	kmcp->kmc_magazine_size.value.ui64	=
3476 	    (cp->cache_flags & KMF_NOMAGAZINE) ?
3477 	    0 : cp->cache_magtype->mt_magsize;
3478 
3479 	kmcp->kmc_alloc.value.ui64		+= cp->cache_full.ml_alloc;
3480 	kmcp->kmc_free.value.ui64		+= cp->cache_empty.ml_alloc;
3481 	buf_avail += cp->cache_full.ml_total * cp->cache_magtype->mt_magsize;
3482 
3483 	reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
3484 	reap = MIN(reap, cp->cache_full.ml_total);
3485 
3486 	mutex_exit(&cp->cache_depot_lock);
3487 
3488 	kmcp->kmc_buf_size.value.ui64	= cp->cache_bufsize;
3489 	kmcp->kmc_align.value.ui64	= cp->cache_align;
3490 	kmcp->kmc_chunk_size.value.ui64	= cp->cache_chunksize;
3491 	kmcp->kmc_slab_size.value.ui64	= cp->cache_slabsize;
3492 	kmcp->kmc_buf_constructed.value.ui64 = buf_avail;
3493 	buf_avail += cp->cache_bufslab;
3494 	kmcp->kmc_buf_avail.value.ui64	= buf_avail;
3495 	kmcp->kmc_buf_inuse.value.ui64	= cp->cache_buftotal - buf_avail;
3496 	kmcp->kmc_buf_total.value.ui64	= cp->cache_buftotal;
3497 	kmcp->kmc_buf_max.value.ui64	= cp->cache_bufmax;
3498 	kmcp->kmc_slab_create.value.ui64	= cp->cache_slab_create;
3499 	kmcp->kmc_slab_destroy.value.ui64	= cp->cache_slab_destroy;
3500 	kmcp->kmc_hash_size.value.ui64	= (cp->cache_flags & KMF_HASH) ?
3501 	    cp->cache_hash_mask + 1 : 0;
3502 	kmcp->kmc_hash_lookup_depth.value.ui64	= cp->cache_lookup_depth;
3503 	kmcp->kmc_hash_rescale.value.ui64	= cp->cache_rescale;
3504 	kmcp->kmc_vmem_source.value.ui64	= cp->cache_arena->vm_id;
3505 	kmcp->kmc_reap.value.ui64	= cp->cache_reap;
3506 
3507 	if (cp->cache_defrag == NULL) {
3508 		kmcp->kmc_move_callbacks.value.ui64	= 0;
3509 		kmcp->kmc_move_yes.value.ui64		= 0;
3510 		kmcp->kmc_move_no.value.ui64		= 0;
3511 		kmcp->kmc_move_later.value.ui64		= 0;
3512 		kmcp->kmc_move_dont_need.value.ui64	= 0;
3513 		kmcp->kmc_move_dont_know.value.ui64	= 0;
3514 		kmcp->kmc_move_hunt_found.value.ui64	= 0;
3515 		kmcp->kmc_move_slabs_freed.value.ui64	= 0;
3516 		kmcp->kmc_defrag.value.ui64		= 0;
3517 		kmcp->kmc_scan.value.ui64		= 0;
3518 		kmcp->kmc_move_reclaimable.value.ui64	= 0;
3519 	} else {
3520 		int64_t reclaimable;
3521 
3522 		kmem_defrag_t *kd = cp->cache_defrag;
3523 		kmcp->kmc_move_callbacks.value.ui64	= kd->kmd_callbacks;
3524 		kmcp->kmc_move_yes.value.ui64		= kd->kmd_yes;
3525 		kmcp->kmc_move_no.value.ui64		= kd->kmd_no;
3526 		kmcp->kmc_move_later.value.ui64		= kd->kmd_later;
3527 		kmcp->kmc_move_dont_need.value.ui64	= kd->kmd_dont_need;
3528 		kmcp->kmc_move_dont_know.value.ui64	= kd->kmd_dont_know;
3529 		kmcp->kmc_move_hunt_found.value.ui64	= 0;
3530 		kmcp->kmc_move_slabs_freed.value.ui64	= kd->kmd_slabs_freed;
3531 		kmcp->kmc_defrag.value.ui64		= kd->kmd_defrags;
3532 		kmcp->kmc_scan.value.ui64		= kd->kmd_scans;
3533 
3534 		reclaimable = cp->cache_bufslab - (cp->cache_maxchunks - 1);
3535 		reclaimable = MAX(reclaimable, 0);
3536 		reclaimable += ((uint64_t)reap *