xref: /illumos-gate/usr/src/uts/common/os/kmem.c (revision c6f039c7)
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27 
28 /*
29  * Kernel memory allocator, as described in the following two papers and a
30  * statement about the consolidator:
31  *
32  * Jeff Bonwick,
33  * The Slab Allocator: An Object-Caching Kernel Memory Allocator.
34  * Proceedings of the Summer 1994 Usenix Conference.
35  * Available as /shared/sac/PSARC/1994/028/materials/kmem.pdf.
36  *
37  * Jeff Bonwick and Jonathan Adams,
38  * Magazines and vmem: Extending the Slab Allocator to Many CPUs and
39  * Arbitrary Resources.
40  * Proceedings of the 2001 Usenix Conference.
41  * Available as /shared/sac/PSARC/2000/550/materials/vmem.pdf.
42  *
43  * kmem Slab Consolidator Big Theory Statement:
44  *
45  * 1. Motivation
46  *
47  * As stated in Bonwick94, slabs provide the following advantages over other
48  * allocation structures in terms of memory fragmentation:
49  *
50  *  - Internal fragmentation (per-buffer wasted space) is minimal.
51  *  - Severe external fragmentation (unused buffers on the free list) is
52  *    unlikely.
53  *
54  * Segregating objects by size eliminates one source of external fragmentation,
55  * and according to Bonwick:
56  *
57  *   The other reason that slabs reduce external fragmentation is that all
58  *   objects in a slab are of the same type, so they have the same lifetime
59  *   distribution. The resulting segregation of short-lived and long-lived
60  *   objects at slab granularity reduces the likelihood of an entire page being
61  *   held hostage due to a single long-lived allocation [Barrett93, Hanson90].
62  *
63  * While unlikely, severe external fragmentation remains possible. Clients that
64  * allocate both short- and long-lived objects from the same cache cannot
65  * anticipate the distribution of long-lived objects within the allocator's slab
66  * implementation. Even a small percentage of long-lived objects distributed
67  * randomly across many slabs can lead to a worst case scenario where the client
68  * frees the majority of its objects and the system gets back almost none of the
69  * slabs. Despite the client doing what it reasonably can to help the system
70  * reclaim memory, the allocator cannot shake free enough slabs because of
71  * lonely allocations stubbornly hanging on. Although the allocator is in a
72  * position to diagnose the fragmentation, there is nothing that the allocator
73  * by itself can do about it. It only takes a single allocated object to prevent
74  * an entire slab from being reclaimed, and any object handed out by
75  * kmem_cache_alloc() is by definition in the client's control. Conversely,
76  * although the client is in a position to move a long-lived object, it has no
77  * way of knowing if the object is causing fragmentation, and if so, where to
78  * move it. A solution necessarily requires further cooperation between the
79  * allocator and the client.
80  *
81  * 2. Move Callback
82  *
83  * The kmem slab consolidator therefore adds a move callback to the
84  * allocator/client interface, improving worst-case external fragmentation in
85  * kmem caches that supply a function to move objects from one memory location
86  * to another. In a situation of low memory kmem attempts to consolidate all of
87  * a cache's slabs at once; otherwise it works slowly to bring external
88  * fragmentation within the 1/8 limit guaranteed for internal fragmentation,
89  * thereby helping to avoid a low memory situation in the future.
90  *
91  * The callback has the following signature:
92  *
93  *   kmem_cbrc_t move(void *old, void *new, size_t size, void *user_arg)
94  *
95  * It supplies the kmem client with two addresses: the allocated object that
96  * kmem wants to move and a buffer selected by kmem for the client to use as the
97  * copy destination. The callback is kmem's way of saying "Please get off of
98  * this buffer and use this one instead." kmem knows where it wants to move the
99  * object in order to best reduce fragmentation. All the client needs to know
100  * about the second argument (void *new) is that it is an allocated, constructed
101  * object ready to take the contents of the old object. When the move function
102  * is called, the system is likely to be low on memory, and the new object
103  * spares the client from having to worry about allocating memory for the
104  * requested move. The third argument supplies the size of the object, in case a
105  * single move function handles multiple caches whose objects differ only in
106  * size (such as zio_buf_512, zio_buf_1024, etc). Finally, the same optional
107  * user argument passed to the constructor, destructor, and reclaim functions is
108  * also passed to the move callback.
109  *
110  * 2.1 Setting the Move Callback
111  *
112  * The client sets the move callback after creating the cache and before
113  * allocating from it:
114  *
115  *	object_cache = kmem_cache_create(...);
116  *      kmem_cache_set_move(object_cache, object_move);
117  *
118  * 2.2 Move Callback Return Values
119  *
120  * Only the client knows about its own data and when is a good time to move it.
121  * The client is cooperating with kmem to return unused memory to the system,
122  * and kmem respectfully accepts this help at the client's convenience. When
123  * asked to move an object, the client can respond with any of the following:
124  *
125  *   typedef enum kmem_cbrc {
126  *           KMEM_CBRC_YES,
127  *           KMEM_CBRC_NO,
128  *           KMEM_CBRC_LATER,
129  *           KMEM_CBRC_DONT_NEED,
130  *           KMEM_CBRC_DONT_KNOW
131  *   } kmem_cbrc_t;
132  *
133  * The client must not explicitly kmem_cache_free() either of the objects passed
134  * to the callback, since kmem wants to free them directly to the slab layer
135  * (bypassing the per-CPU magazine layer). The response tells kmem which of the
136  * objects to free:
137  *
138  *       YES: (Did it) The client moved the object, so kmem frees the old one.
139  *        NO: (Never) The client refused, so kmem frees the new object (the
140  *            unused copy destination). kmem also marks the slab of the old
141  *            object so as not to bother the client with further callbacks for
142  *            that object as long as the slab remains on the partial slab list.
143  *            (The system won't be getting the slab back as long as the
144  *            immovable object holds it hostage, so there's no point in moving
145  *            any of its objects.)
146  *     LATER: The client is using the object and cannot move it now, so kmem
147  *            frees the new object (the unused copy destination). kmem still
148  *            attempts to move other objects off the slab, since it expects to
149  *            succeed in clearing the slab in a later callback. The client
150  *            should use LATER instead of NO if the object is likely to become
151  *            movable very soon.
152  * DONT_NEED: The client no longer needs the object, so kmem frees the old along
153  *            with the new object (the unused copy destination). This response
154  *            is the client's opportunity to be a model citizen and give back as
155  *            much as it can.
156  * DONT_KNOW: The client does not know about the object because
157  *            a) the client has just allocated the object and not yet put it
158  *               wherever it expects to find known objects
159  *            b) the client has removed the object from wherever it expects to
160  *               find known objects and is about to free it, or
161  *            c) the client has freed the object.
162  *            In all these cases (a, b, and c) kmem frees the new object (the
163  *            unused copy destination).  In the first case, the object is in
164  *            use and the correct action is that for LATER; in the latter two
165  *            cases, we know that the object is either freed or about to be
166  *            freed, in which case it is either already in a magazine or about
167  *            to be in one.  In these cases, we know that the object will either
168  *            be reallocated and reused, or it will end up in a full magazine
169  *            that will be reaped (thereby liberating the slab).  Because it
170  *            is prohibitively expensive to differentiate these cases, and
171  *            because the defrag code is executed when we're low on memory
172  *            (thereby biasing the system to reclaim full magazines) we treat
173  *            all DONT_KNOW cases as LATER and rely on cache reaping to
174  *            generally clean up full magazines.  While we take the same action
175  *            for these cases, we maintain their semantic distinction:  if
176  *            defragmentation is not occurring, it is useful to know if this
177  *            is due to objects in use (LATER) or objects in an unknown state
178  *            of transition (DONT_KNOW).
179  *
180  * 2.3 Object States
181  *
182  * Neither kmem nor the client can be assumed to know the object's whereabouts
183  * at the time of the callback. An object belonging to a kmem cache may be in
184  * any of the following states:
185  *
186  * 1. Uninitialized on the slab
187  * 2. Allocated from the slab but not constructed (still uninitialized)
188  * 3. Allocated from the slab, constructed, but not yet ready for business
189  *    (not in a valid state for the move callback)
190  * 4. In use (valid and known to the client)
191  * 5. About to be freed (no longer in a valid state for the move callback)
192  * 6. Freed to a magazine (still constructed)
193  * 7. Allocated from a magazine, not yet ready for business (not in a valid
194  *    state for the move callback), and about to return to state #4
195  * 8. Deconstructed on a magazine that is about to be freed
196  * 9. Freed to the slab
197  *
198  * Since the move callback may be called at any time while the object is in any
199  * of the above states (except state #1), the client needs a safe way to
200  * determine whether or not it knows about the object. Specifically, the client
201  * needs to know whether or not the object is in state #4, the only state in
202  * which a move is valid. If the object is in any other state, the client should
203  * immediately return KMEM_CBRC_DONT_KNOW, since it is unsafe to access any of
204  * the object's fields.
205  *
206  * Note that although an object may be in state #4 when kmem initiates the move
207  * request, the object may no longer be in that state by the time kmem actually
208  * calls the move function. Not only does the client free objects
209  * asynchronously, kmem itself puts move requests on a queue where thay are
210  * pending until kmem processes them from another context. Also, objects freed
211  * to a magazine appear allocated from the point of view of the slab layer, so
212  * kmem may even initiate requests for objects in a state other than state #4.
213  *
214  * 2.3.1 Magazine Layer
215  *
216  * An important insight revealed by the states listed above is that the magazine
217  * layer is populated only by kmem_cache_free(). Magazines of constructed
218  * objects are never populated directly from the slab layer (which contains raw,
219  * unconstructed objects). Whenever an allocation request cannot be satisfied
220  * from the magazine layer, the magazines are bypassed and the request is
221  * satisfied from the slab layer (creating a new slab if necessary). kmem calls
222  * the object constructor only when allocating from the slab layer, and only in
223  * response to kmem_cache_alloc() or to prepare the destination buffer passed in
224  * the move callback. kmem does not preconstruct objects in anticipation of
225  * kmem_cache_alloc().
226  *
227  * 2.3.2 Object Constructor and Destructor
228  *
229  * If the client supplies a destructor, it must be valid to call the destructor
230  * on a newly created object (immediately after the constructor).
231  *
232  * 2.4 Recognizing Known Objects
233  *
234  * There is a simple test to determine safely whether or not the client knows
235  * about a given object in the move callback. It relies on the fact that kmem
236  * guarantees that the object of the move callback has only been touched by the
237  * client itself or else by kmem. kmem does this by ensuring that none of the
238  * cache's slabs are freed to the virtual memory (VM) subsystem while a move
239  * callback is pending. When the last object on a slab is freed, if there is a
240  * pending move, kmem puts the slab on a per-cache dead list and defers freeing
241  * slabs on that list until all pending callbacks are completed. That way,
242  * clients can be certain that the object of a move callback is in one of the
243  * states listed above, making it possible to distinguish known objects (in
244  * state #4) using the two low order bits of any pointer member (with the
245  * exception of 'char *' or 'short *' which may not be 4-byte aligned on some
246  * platforms).
247  *
248  * The test works as long as the client always transitions objects from state #4
249  * (known, in use) to state #5 (about to be freed, invalid) by setting the low
250  * order bit of the client-designated pointer member. Since kmem only writes
251  * invalid memory patterns, such as 0xbaddcafe to uninitialized memory and
252  * 0xdeadbeef to freed memory, any scribbling on the object done by kmem is
253  * guaranteed to set at least one of the two low order bits. Therefore, given an
254  * object with a back pointer to a 'container_t *o_container', the client can
255  * test
256  *
257  *      container_t *container = object->o_container;
258  *      if ((uintptr_t)container & 0x3) {
259  *              return (KMEM_CBRC_DONT_KNOW);
260  *      }
261  *
262  * Typically, an object will have a pointer to some structure with a list or
263  * hash where objects from the cache are kept while in use. Assuming that the
264  * client has some way of knowing that the container structure is valid and will
265  * not go away during the move, and assuming that the structure includes a lock
266  * to protect whatever collection is used, then the client would continue as
267  * follows:
268  *
269  *	// Ensure that the container structure does not go away.
270  *      if (container_hold(container) == 0) {
271  *              return (KMEM_CBRC_DONT_KNOW);
272  *      }
273  *      mutex_enter(&container->c_objects_lock);
274  *      if (container != object->o_container) {
275  *              mutex_exit(&container->c_objects_lock);
276  *              container_rele(container);
277  *              return (KMEM_CBRC_DONT_KNOW);
278  *      }
279  *
280  * At this point the client knows that the object cannot be freed as long as
281  * c_objects_lock is held. Note that after acquiring the lock, the client must
282  * recheck the o_container pointer in case the object was removed just before
283  * acquiring the lock.
284  *
285  * When the client is about to free an object, it must first remove that object
286  * from the list, hash, or other structure where it is kept. At that time, to
287  * mark the object so it can be distinguished from the remaining, known objects,
288  * the client sets the designated low order bit:
289  *
290  *      mutex_enter(&container->c_objects_lock);
291  *      object->o_container = (void *)((uintptr_t)object->o_container | 0x1);
292  *      list_remove(&container->c_objects, object);
293  *      mutex_exit(&container->c_objects_lock);
294  *
295  * In the common case, the object is freed to the magazine layer, where it may
296  * be reused on a subsequent allocation without the overhead of calling the
297  * constructor. While in the magazine it appears allocated from the point of
298  * view of the slab layer, making it a candidate for the move callback. Most
299  * objects unrecognized by the client in the move callback fall into this
300  * category and are cheaply distinguished from known objects by the test
301  * described earlier. Because searching magazines is prohibitively expensive
302  * for kmem, clients that do not mark freed objects (and therefore return
303  * KMEM_CBRC_DONT_KNOW for large numbers of objects) may find defragmentation
304  * efficacy reduced.
305  *
306  * Invalidating the designated pointer member before freeing the object marks
307  * the object to be avoided in the callback, and conversely, assigning a valid
308  * value to the designated pointer member after allocating the object makes the
309  * object fair game for the callback:
310  *
311  *      ... allocate object ...
312  *      ... set any initial state not set by the constructor ...
313  *
314  *      mutex_enter(&container->c_objects_lock);
315  *      list_insert_tail(&container->c_objects, object);
316  *      membar_producer();
317  *      object->o_container = container;
318  *      mutex_exit(&container->c_objects_lock);
319  *
320  * Note that everything else must be valid before setting o_container makes the
321  * object fair game for the move callback. The membar_producer() call ensures
322  * that all the object's state is written to memory before setting the pointer
323  * that transitions the object from state #3 or #7 (allocated, constructed, not
324  * yet in use) to state #4 (in use, valid). That's important because the move
325  * function has to check the validity of the pointer before it can safely
326  * acquire the lock protecting the collection where it expects to find known
327  * objects.
328  *
329  * This method of distinguishing known objects observes the usual symmetry:
330  * invalidating the designated pointer is the first thing the client does before
331  * freeing the object, and setting the designated pointer is the last thing the
332  * client does after allocating the object. Of course, the client is not
333  * required to use this method. Fundamentally, how the client recognizes known
334  * objects is completely up to the client, but this method is recommended as an
335  * efficient and safe way to take advantage of the guarantees made by kmem. If
336  * the entire object is arbitrary data without any markable bits from a suitable
337  * pointer member, then the client must find some other method, such as
338  * searching a hash table of known objects.
339  *
340  * 2.5 Preventing Objects From Moving
341  *
342  * Besides a way to distinguish known objects, the other thing that the client
343  * needs is a strategy to ensure that an object will not move while the client
344  * is actively using it. The details of satisfying this requirement tend to be
345  * highly cache-specific. It might seem that the same rules that let a client
346  * remove an object safely should also decide when an object can be moved
347  * safely. However, any object state that makes a removal attempt invalid is
348  * likely to be long-lasting for objects that the client does not expect to
349  * remove. kmem knows nothing about the object state and is equally likely (from
350  * the client's point of view) to request a move for any object in the cache,
351  * whether prepared for removal or not. Even a low percentage of objects stuck
352  * in place by unremovability will defeat the consolidator if the stuck objects
353  * are the same long-lived allocations likely to hold slabs hostage.
354  * Fundamentally, the consolidator is not aimed at common cases. Severe external
355  * fragmentation is a worst case scenario manifested as sparsely allocated
356  * slabs, by definition a low percentage of the cache's objects. When deciding
357  * what makes an object movable, keep in mind the goal of the consolidator: to
358  * bring worst-case external fragmentation within the limits guaranteed for
359  * internal fragmentation. Removability is a poor criterion if it is likely to
360  * exclude more than an insignificant percentage of objects for long periods of
361  * time.
362  *
363  * A tricky general solution exists, and it has the advantage of letting you
364  * move any object at almost any moment, practically eliminating the likelihood
365  * that an object can hold a slab hostage. However, if there is a cache-specific
366  * way to ensure that an object is not actively in use in the vast majority of
367  * cases, a simpler solution that leverages this cache-specific knowledge is
368  * preferred.
369  *
370  * 2.5.1 Cache-Specific Solution
371  *
372  * As an example of a cache-specific solution, the ZFS znode cache takes
373  * advantage of the fact that the vast majority of znodes are only being
374  * referenced from the DNLC. (A typical case might be a few hundred in active
375  * use and a hundred thousand in the DNLC.) In the move callback, after the ZFS
376  * client has established that it recognizes the znode and can access its fields
377  * safely (using the method described earlier), it then tests whether the znode
378  * is referenced by anything other than the DNLC. If so, it assumes that the
379  * znode may be in active use and is unsafe to move, so it drops its locks and
380  * returns KMEM_CBRC_LATER. The advantage of this strategy is that everywhere
381  * else znodes are used, no change is needed to protect against the possibility
382  * of the znode moving. The disadvantage is that it remains possible for an
383  * application to hold a znode slab hostage with an open file descriptor.
384  * However, this case ought to be rare and the consolidator has a way to deal
385  * with it: If the client responds KMEM_CBRC_LATER repeatedly for the same
386  * object, kmem eventually stops believing it and treats the slab as if the
387  * client had responded KMEM_CBRC_NO. Having marked the hostage slab, kmem can
388  * then focus on getting it off of the partial slab list by allocating rather
389  * than freeing all of its objects. (Either way of getting a slab off the
390  * free list reduces fragmentation.)
391  *
392  * 2.5.2 General Solution
393  *
394  * The general solution, on the other hand, requires an explicit hold everywhere
395  * the object is used to prevent it from moving. To keep the client locking
396  * strategy as uncomplicated as possible, kmem guarantees the simplifying
397  * assumption that move callbacks are sequential, even across multiple caches.
398  * Internally, a global queue processed by a single thread supports all caches
399  * implementing the callback function. No matter how many caches supply a move
400  * function, the consolidator never moves more than one object at a time, so the
401  * client does not have to worry about tricky lock ordering involving several
402  * related objects from different kmem caches.
403  *
404  * The general solution implements the explicit hold as a read-write lock, which
405  * allows multiple readers to access an object from the cache simultaneously
406  * while a single writer is excluded from moving it. A single rwlock for the
407  * entire cache would lock out all threads from using any of the cache's objects
408  * even though only a single object is being moved, so to reduce contention,
409  * the client can fan out the single rwlock into an array of rwlocks hashed by
410  * the object address, making it probable that moving one object will not
411  * prevent other threads from using a different object. The rwlock cannot be a
412  * member of the object itself, because the possibility of the object moving
413  * makes it unsafe to access any of the object's fields until the lock is
414  * acquired.
415  *
416  * Assuming a small, fixed number of locks, it's possible that multiple objects
417  * will hash to the same lock. A thread that needs to use multiple objects in
418  * the same function may acquire the same lock multiple times. Since rwlocks are
419  * reentrant for readers, and since there is never more than a single writer at
420  * a time (assuming that the client acquires the lock as a writer only when
421  * moving an object inside the callback), there would seem to be no problem.
422  * However, a client locking multiple objects in the same function must handle
423  * one case of potential deadlock: Assume that thread A needs to prevent both
424  * object 1 and object 2 from moving, and thread B, the callback, meanwhile
425  * tries to move object 3. It's possible, if objects 1, 2, and 3 all hash to the
426  * same lock, that thread A will acquire the lock for object 1 as a reader
427  * before thread B sets the lock's write-wanted bit, preventing thread A from
428  * reacquiring the lock for object 2 as a reader. Unable to make forward
429  * progress, thread A will never release the lock for object 1, resulting in
430  * deadlock.
431  *
432  * There are two ways of avoiding the deadlock just described. The first is to
433  * use rw_tryenter() rather than rw_enter() in the callback function when
434  * attempting to acquire the lock as a writer. If tryenter discovers that the
435  * same object (or another object hashed to the same lock) is already in use, it
436  * aborts the callback and returns KMEM_CBRC_LATER. The second way is to use
437  * rprwlock_t (declared in common/fs/zfs/sys/rprwlock.h) instead of rwlock_t,
438  * since it allows a thread to acquire the lock as a reader in spite of a
439  * waiting writer. This second approach insists on moving the object now, no
440  * matter how many readers the move function must wait for in order to do so,
441  * and could delay the completion of the callback indefinitely (blocking
442  * callbacks to other clients). In practice, a less insistent callback using
443  * rw_tryenter() returns KMEM_CBRC_LATER infrequently enough that there seems
444  * little reason to use anything else.
445  *
446  * Avoiding deadlock is not the only problem that an implementation using an
447  * explicit hold needs to solve. Locking the object in the first place (to
448  * prevent it from moving) remains a problem, since the object could move
449  * between the time you obtain a pointer to the object and the time you acquire
450  * the rwlock hashed to that pointer value. Therefore the client needs to
451  * recheck the value of the pointer after acquiring the lock, drop the lock if
452  * the value has changed, and try again. This requires a level of indirection:
453  * something that points to the object rather than the object itself, that the
454  * client can access safely while attempting to acquire the lock. (The object
455  * itself cannot be referenced safely because it can move at any time.)
456  * The following lock-acquisition function takes whatever is safe to reference
457  * (arg), follows its pointer to the object (using function f), and tries as
458  * often as necessary to acquire the hashed lock and verify that the object
459  * still has not moved:
460  *
461  *      object_t *
462  *      object_hold(object_f f, void *arg)
463  *      {
464  *              object_t *op;
465  *
466  *              op = f(arg);
467  *              if (op == NULL) {
468  *                      return (NULL);
469  *              }
470  *
471  *              rw_enter(OBJECT_RWLOCK(op), RW_READER);
472  *              while (op != f(arg)) {
473  *                      rw_exit(OBJECT_RWLOCK(op));
474  *                      op = f(arg);
475  *                      if (op == NULL) {
476  *                              break;
477  *                      }
478  *                      rw_enter(OBJECT_RWLOCK(op), RW_READER);
479  *              }
480  *
481  *              return (op);
482  *      }
483  *
484  * The OBJECT_RWLOCK macro hashes the object address to obtain the rwlock. The
485  * lock reacquisition loop, while necessary, almost never executes. The function
486  * pointer f (used to obtain the object pointer from arg) has the following type
487  * definition:
488  *
489  *      typedef object_t *(*object_f)(void *arg);
490  *
491  * An object_f implementation is likely to be as simple as accessing a structure
492  * member:
493  *
494  *      object_t *
495  *      s_object(void *arg)
496  *      {
497  *              something_t *sp = arg;
498  *              return (sp->s_object);
499  *      }
500  *
501  * The flexibility of a function pointer allows the path to the object to be
502  * arbitrarily complex and also supports the notion that depending on where you
503  * are using the object, you may need to get it from someplace different.
504  *
505  * The function that releases the explicit hold is simpler because it does not
506  * have to worry about the object moving:
507  *
508  *      void
509  *      object_rele(object_t *op)
510  *      {
511  *              rw_exit(OBJECT_RWLOCK(op));
512  *      }
513  *
514  * The caller is spared these details so that obtaining and releasing an
515  * explicit hold feels like a simple mutex_enter()/mutex_exit() pair. The caller
516  * of object_hold() only needs to know that the returned object pointer is valid
517  * if not NULL and that the object will not move until released.
518  *
519  * Although object_hold() prevents an object from moving, it does not prevent it
520  * from being freed. The caller must take measures before calling object_hold()
521  * (afterwards is too late) to ensure that the held object cannot be freed. The
522  * caller must do so without accessing the unsafe object reference, so any lock
523  * or reference count used to ensure the continued existence of the object must
524  * live outside the object itself.
525  *
526  * Obtaining a new object is a special case where an explicit hold is impossible
527  * for the caller. Any function that returns a newly allocated object (either as
528  * a return value, or as an in-out paramter) must return it already held; after
529  * the caller gets it is too late, since the object cannot be safely accessed
530  * without the level of indirection described earlier. The following
531  * object_alloc() example uses the same code shown earlier to transition a new
532  * object into the state of being recognized (by the client) as a known object.
533  * The function must acquire the hold (rw_enter) before that state transition
534  * makes the object movable:
535  *
536  *      static object_t *
537  *      object_alloc(container_t *container)
538  *      {
539  *              object_t *object = kmem_cache_alloc(object_cache, 0);
540  *              ... set any initial state not set by the constructor ...
541  *              rw_enter(OBJECT_RWLOCK(object), RW_READER);
542  *              mutex_enter(&container->c_objects_lock);
543  *              list_insert_tail(&container->c_objects, object);
544  *              membar_producer();
545  *              object->o_container = container;
546  *              mutex_exit(&container->c_objects_lock);
547  *              return (object);
548  *      }
549  *
550  * Functions that implicitly acquire an object hold (any function that calls
551  * object_alloc() to supply an object for the caller) need to be carefully noted
552  * so that the matching object_rele() is not neglected. Otherwise, leaked holds
553  * prevent all objects hashed to the affected rwlocks from ever being moved.
554  *
555  * The pointer to a held object can be hashed to the holding rwlock even after
556  * the object has been freed. Although it is possible to release the hold
557  * after freeing the object, you may decide to release the hold implicitly in
558  * whatever function frees the object, so as to release the hold as soon as
559  * possible, and for the sake of symmetry with the function that implicitly
560  * acquires the hold when it allocates the object. Here, object_free() releases
561  * the hold acquired by object_alloc(). Its implicit object_rele() forms a
562  * matching pair with object_hold():
563  *
564  *      void
565  *      object_free(object_t *object)
566  *      {
567  *              container_t *container;
568  *
569  *              ASSERT(object_held(object));
570  *              container = object->o_container;
571  *              mutex_enter(&container->c_objects_lock);
572  *              object->o_container =
573  *                  (void *)((uintptr_t)object->o_container | 0x1);
574  *              list_remove(&container->c_objects, object);
575  *              mutex_exit(&container->c_objects_lock);
576  *              object_rele(object);
577  *              kmem_cache_free(object_cache, object);
578  *      }
579  *
580  * Note that object_free() cannot safely accept an object pointer as an argument
581  * unless the object is already held. Any function that calls object_free()
582  * needs to be carefully noted since it similarly forms a matching pair with
583  * object_hold().
584  *
585  * To complete the picture, the following callback function implements the
586  * general solution by moving objects only if they are currently unheld:
587  *
588  *      static kmem_cbrc_t
589  *      object_move(void *buf, void *newbuf, size_t size, void *arg)
590  *      {
591  *              object_t *op = buf, *np = newbuf;
592  *              container_t *container;
593  *
594  *              container = op->o_container;
595  *              if ((uintptr_t)container & 0x3) {
596  *                      return (KMEM_CBRC_DONT_KNOW);
597  *              }
598  *
599  *	        // Ensure that the container structure does not go away.
600  *              if (container_hold(container) == 0) {
601  *                      return (KMEM_CBRC_DONT_KNOW);
602  *              }
603  *
604  *              mutex_enter(&container->c_objects_lock);
605  *              if (container != op->o_container) {
606  *                      mutex_exit(&container->c_objects_lock);
607  *                      container_rele(container);
608  *                      return (KMEM_CBRC_DONT_KNOW);
609  *              }
610  *
611  *              if (rw_tryenter(OBJECT_RWLOCK(op), RW_WRITER) == 0) {
612  *                      mutex_exit(&container->c_objects_lock);
613  *                      container_rele(container);
614  *                      return (KMEM_CBRC_LATER);
615  *              }
616  *
617  *              object_move_impl(op, np); // critical section
618  *              rw_exit(OBJECT_RWLOCK(op));
619  *
620  *              op->o_container = (void *)((uintptr_t)op->o_container | 0x1);
621  *              list_link_replace(&op->o_link_node, &np->o_link_node);
622  *              mutex_exit(&container->c_objects_lock);
623  *              container_rele(container);
624  *              return (KMEM_CBRC_YES);
625  *      }
626  *
627  * Note that object_move() must invalidate the designated o_container pointer of
628  * the old object in the same way that object_free() does, since kmem will free
629  * the object in response to the KMEM_CBRC_YES return value.
630  *
631  * The lock order in object_move() differs from object_alloc(), which locks
632  * OBJECT_RWLOCK first and &container->c_objects_lock second, but as long as the
633  * callback uses rw_tryenter() (preventing the deadlock described earlier), it's
634  * not a problem. Holding the lock on the object list in the example above
635  * through the entire callback not only prevents the object from going away, it
636  * also allows you to lock the list elsewhere and know that none of its elements
637  * will move during iteration.
638  *
639  * Adding an explicit hold everywhere an object from the cache is used is tricky
640  * and involves much more change to client code than a cache-specific solution
641  * that leverages existing state to decide whether or not an object is
642  * movable. However, this approach has the advantage that no object remains
643  * immovable for any significant length of time, making it extremely unlikely
644  * that long-lived allocations can continue holding slabs hostage; and it works
645  * for any cache.
646  *
647  * 3. Consolidator Implementation
648  *
649  * Once the client supplies a move function that a) recognizes known objects and
650  * b) avoids moving objects that are actively in use, the remaining work is up
651  * to the consolidator to decide which objects to move and when to issue
652  * callbacks.
653  *
654  * The consolidator relies on the fact that a cache's slabs are ordered by
655  * usage. Each slab has a fixed number of objects. Depending on the slab's
656  * "color" (the offset of the first object from the beginning of the slab;
657  * offsets are staggered to mitigate false sharing of cache lines) it is either
658  * the maximum number of objects per slab determined at cache creation time or
659  * else the number closest to the maximum that fits within the space remaining
660  * after the initial offset. A completely allocated slab may contribute some
661  * internal fragmentation (per-slab overhead) but no external fragmentation, so
662  * it is of no interest to the consolidator. At the other extreme, slabs whose
663  * objects have all been freed to the slab are released to the virtual memory
664  * (VM) subsystem (objects freed to magazines are still allocated as far as the
665  * slab is concerned). External fragmentation exists when there are slabs
666  * somewhere between these extremes. A partial slab has at least one but not all
667  * of its objects allocated. The more partial slabs, and the fewer allocated
668  * objects on each of them, the higher the fragmentation. Hence the
669  * consolidator's overall strategy is to reduce the number of partial slabs by
670  * moving allocated objects from the least allocated slabs to the most allocated
671  * slabs.
672  *
673  * Partial slabs are kept in an AVL tree ordered by usage. Completely allocated
674  * slabs are kept separately in an unordered list. Since the majority of slabs
675  * tend to be completely allocated (a typical unfragmented cache may have
676  * thousands of complete slabs and only a single partial slab), separating
677  * complete slabs improves the efficiency of partial slab ordering, since the
678  * complete slabs do not affect the depth or balance of the AVL tree. This
679  * ordered sequence of partial slabs acts as a "free list" supplying objects for
680  * allocation requests.
681  *
682  * Objects are always allocated from the first partial slab in the free list,
683  * where the allocation is most likely to eliminate a partial slab (by
684  * completely allocating it). Conversely, when a single object from a completely
685  * allocated slab is freed to the slab, that slab is added to the front of the
686  * free list. Since most free list activity involves highly allocated slabs
687  * coming and going at the front of the list, slabs tend naturally toward the
688  * ideal order: highly allocated at the front, sparsely allocated at the back.
689  * Slabs with few allocated objects are likely to become completely free if they
690  * keep a safe distance away from the front of the free list. Slab misorders
691  * interfere with the natural tendency of slabs to become completely free or
692  * completely allocated. For example, a slab with a single allocated object
693  * needs only a single free to escape the cache; its natural desire is
694  * frustrated when it finds itself at the front of the list where a second
695  * allocation happens just before the free could have released it. Another slab
696  * with all but one object allocated might have supplied the buffer instead, so
697  * that both (as opposed to neither) of the slabs would have been taken off the
698  * free list.
699  *
700  * Although slabs tend naturally toward the ideal order, misorders allowed by a
701  * simple list implementation defeat the consolidator's strategy of merging
702  * least- and most-allocated slabs. Without an AVL tree to guarantee order, kmem
703  * needs another way to fix misorders to optimize its callback strategy. One
704  * approach is to periodically scan a limited number of slabs, advancing a
705  * marker to hold the current scan position, and to move extreme misorders to
706  * the front or back of the free list and to the front or back of the current
707  * scan range. By making consecutive scan ranges overlap by one slab, the least
708  * allocated slab in the current range can be carried along from the end of one
709  * scan to the start of the next.
710  *
711  * Maintaining partial slabs in an AVL tree relieves kmem of this additional
712  * task, however. Since most of the cache's activity is in the magazine layer,
713  * and allocations from the slab layer represent only a startup cost, the
714  * overhead of maintaining a balanced tree is not a significant concern compared
715  * to the opportunity of reducing complexity by eliminating the partial slab
716  * scanner just described. The overhead of an AVL tree is minimized by
717  * maintaining only partial slabs in the tree and keeping completely allocated
718  * slabs separately in a list. To avoid increasing the size of the slab
719  * structure the AVL linkage pointers are reused for the slab's list linkage,
720  * since the slab will always be either partial or complete, never stored both
721  * ways at the same time. To further minimize the overhead of the AVL tree the
722  * compare function that orders partial slabs by usage divides the range of
723  * allocated object counts into bins such that counts within the same bin are
724  * considered equal. Binning partial slabs makes it less likely that allocating
725  * or freeing a single object will change the slab's order, requiring a tree
726  * reinsertion (an avl_remove() followed by an avl_add(), both potentially
727  * requiring some rebalancing of the tree). Allocation counts closest to
728  * completely free and completely allocated are left unbinned (finely sorted) to
729  * better support the consolidator's strategy of merging slabs at either
730  * extreme.
731  *
732  * 3.1 Assessing Fragmentation and Selecting Candidate Slabs
733  *
734  * The consolidator piggybacks on the kmem maintenance thread and is called on
735  * the same interval as kmem_cache_update(), once per cache every fifteen
736  * seconds. kmem maintains a running count of unallocated objects in the slab
737  * layer (cache_bufslab). The consolidator checks whether that number exceeds
738  * 12.5% (1/8) of the total objects in the cache (cache_buftotal), and whether
739  * there is a significant number of slabs in the cache (arbitrarily a minimum
740  * 101 total slabs). Unused objects that have fallen out of the magazine layer's
741  * working set are included in the assessment, and magazines in the depot are
742  * reaped if those objects would lift cache_bufslab above the fragmentation
743  * threshold. Once the consolidator decides that a cache is fragmented, it looks
744  * for a candidate slab to reclaim, starting at the end of the partial slab free
745  * list and scanning backwards. At first the consolidator is choosy: only a slab
746  * with fewer than 12.5% (1/8) of its objects allocated qualifies (or else a
747  * single allocated object, regardless of percentage). If there is difficulty
748  * finding a candidate slab, kmem raises the allocation threshold incrementally,
749  * up to a maximum 87.5% (7/8), so that eventually the consolidator will reduce
750  * external fragmentation (unused objects on the free list) below 12.5% (1/8),
751  * even in the worst case of every slab in the cache being almost 7/8 allocated.
752  * The threshold can also be lowered incrementally when candidate slabs are easy
753  * to find, and the threshold is reset to the minimum 1/8 as soon as the cache
754  * is no longer fragmented.
755  *
756  * 3.2 Generating Callbacks
757  *
758  * Once an eligible slab is chosen, a callback is generated for every allocated
759  * object on the slab, in the hope that the client will move everything off the
760  * slab and make it reclaimable. Objects selected as move destinations are
761  * chosen from slabs at the front of the free list. Assuming slabs in the ideal
762  * order (most allocated at the front, least allocated at the back) and a
763  * cooperative client, the consolidator will succeed in removing slabs from both
764  * ends of the free list, completely allocating on the one hand and completely
765  * freeing on the other. Objects selected as move destinations are allocated in
766  * the kmem maintenance thread where move requests are enqueued. A separate
767  * callback thread removes pending callbacks from the queue and calls the
768  * client. The separate thread ensures that client code (the move function) does
769  * not interfere with internal kmem maintenance tasks. A map of pending
770  * callbacks keyed by object address (the object to be moved) is checked to
771  * ensure that duplicate callbacks are not generated for the same object.
772  * Allocating the move destination (the object to move to) prevents subsequent
773  * callbacks from selecting the same destination as an earlier pending callback.
774  *
775  * Move requests can also be generated by kmem_cache_reap() when the system is
776  * desperate for memory and by kmem_cache_move_notify(), called by the client to
777  * notify kmem that a move refused earlier with KMEM_CBRC_LATER is now possible.
778  * The map of pending callbacks is protected by the same lock that protects the
779  * slab layer.
780  *
781  * When the system is desperate for memory, kmem does not bother to determine
782  * whether or not the cache exceeds the fragmentation threshold, but tries to
783  * consolidate as many slabs as possible. Normally, the consolidator chews
784  * slowly, one sparsely allocated slab at a time during each maintenance
785  * interval that the cache is fragmented. When desperate, the consolidator
786  * starts at the last partial slab and enqueues callbacks for every allocated
787  * object on every partial slab, working backwards until it reaches the first
788  * partial slab. The first partial slab, meanwhile, advances in pace with the
789  * consolidator as allocations to supply move destinations for the enqueued
790  * callbacks use up the highly allocated slabs at the front of the free list.
791  * Ideally, the overgrown free list collapses like an accordion, starting at
792  * both ends and ending at the center with a single partial slab.
793  *
794  * 3.3 Client Responses
795  *
796  * When the client returns KMEM_CBRC_NO in response to the move callback, kmem
797  * marks the slab that supplied the stuck object non-reclaimable and moves it to
798  * front of the free list. The slab remains marked as long as it remains on the
799  * free list, and it appears more allocated to the partial slab compare function
800  * than any unmarked slab, no matter how many of its objects are allocated.
801  * Since even one immovable object ties up the entire slab, the goal is to
802  * completely allocate any slab that cannot be completely freed. kmem does not
803  * bother generating callbacks to move objects from a marked slab unless the
804  * system is desperate.
805  *
806  * When the client responds KMEM_CBRC_LATER, kmem increments a count for the
807  * slab. If the client responds LATER too many times, kmem disbelieves and
808  * treats the response as a NO. The count is cleared when the slab is taken off
809  * the partial slab list or when the client moves one of the slab's objects.
810  *
811  * 4. Observability
812  *
813  * A kmem cache's external fragmentation is best observed with 'mdb -k' using
814  * the ::kmem_slabs dcmd. For a complete description of the command, enter
815  * '::help kmem_slabs' at the mdb prompt.
816  */
817 
818 #include <sys/kmem_impl.h>
819 #include <sys/vmem_impl.h>
820 #include <sys/param.h>
821 #include <sys/sysmacros.h>
822 #include <sys/vm.h>
823 #include <sys/proc.h>
824 #include <sys/tuneable.h>
825 #include <sys/systm.h>
826 #include <sys/cmn_err.h>
827 #include <sys/debug.h>
828 #include <sys/sdt.h>
829 #include <sys/mutex.h>
830 #include <sys/bitmap.h>
831 #include <sys/atomic.h>
832 #include <sys/kobj.h>
833 #include <sys/disp.h>
834 #include <vm/seg_kmem.h>
835 #include <sys/log.h>
836 #include <sys/callb.h>
837 #include <sys/taskq.h>
838 #include <sys/modctl.h>
839 #include <sys/reboot.h>
840 #include <sys/id32.h>
841 #include <sys/zone.h>
842 #include <sys/netstack.h>
843 #ifdef	DEBUG
844 #include <sys/random.h>
845 #endif
846 
847 extern void streams_msg_init(void);
848 extern int segkp_fromheap;
849 extern void segkp_cache_free(void);
850 extern int callout_init_done;
851 
852 struct kmem_cache_kstat {
853 	kstat_named_t	kmc_buf_size;
854 	kstat_named_t	kmc_align;
855 	kstat_named_t	kmc_chunk_size;
856 	kstat_named_t	kmc_slab_size;
857 	kstat_named_t	kmc_alloc;
858 	kstat_named_t	kmc_alloc_fail;
859 	kstat_named_t	kmc_free;
860 	kstat_named_t	kmc_depot_alloc;
861 	kstat_named_t	kmc_depot_free;
862 	kstat_named_t	kmc_depot_contention;
863 	kstat_named_t	kmc_slab_alloc;
864 	kstat_named_t	kmc_slab_free;
865 	kstat_named_t	kmc_buf_constructed;
866 	kstat_named_t	kmc_buf_avail;
867 	kstat_named_t	kmc_buf_inuse;
868 	kstat_named_t	kmc_buf_total;
869 	kstat_named_t	kmc_buf_max;
870 	kstat_named_t	kmc_slab_create;
871 	kstat_named_t	kmc_slab_destroy;
872 	kstat_named_t	kmc_vmem_source;
873 	kstat_named_t	kmc_hash_size;
874 	kstat_named_t	kmc_hash_lookup_depth;
875 	kstat_named_t	kmc_hash_rescale;
876 	kstat_named_t	kmc_full_magazines;
877 	kstat_named_t	kmc_empty_magazines;
878 	kstat_named_t	kmc_magazine_size;
879 	kstat_named_t	kmc_reap; /* number of kmem_cache_reap() calls */
880 	kstat_named_t	kmc_defrag; /* attempts to defrag all partial slabs */
881 	kstat_named_t	kmc_scan; /* attempts to defrag one partial slab */
882 	kstat_named_t	kmc_move_callbacks; /* sum of yes, no, later, dn, dk */
883 	kstat_named_t	kmc_move_yes;
884 	kstat_named_t	kmc_move_no;
885 	kstat_named_t	kmc_move_later;
886 	kstat_named_t	kmc_move_dont_need;
887 	kstat_named_t	kmc_move_dont_know; /* obj unrecognized by client ... */
888 	kstat_named_t	kmc_move_hunt_found; /* ... but found in mag layer */
889 	kstat_named_t	kmc_move_slabs_freed; /* slabs freed by consolidator */
890 	kstat_named_t	kmc_move_reclaimable; /* buffers, if consolidator ran */
891 } kmem_cache_kstat = {
892 	{ "buf_size",		KSTAT_DATA_UINT64 },
893 	{ "align",		KSTAT_DATA_UINT64 },
894 	{ "chunk_size",		KSTAT_DATA_UINT64 },
895 	{ "slab_size",		KSTAT_DATA_UINT64 },
896 	{ "alloc",		KSTAT_DATA_UINT64 },
897 	{ "alloc_fail",		KSTAT_DATA_UINT64 },
898 	{ "free",		KSTAT_DATA_UINT64 },
899 	{ "depot_alloc",	KSTAT_DATA_UINT64 },
900 	{ "depot_free",		KSTAT_DATA_UINT64 },
901 	{ "depot_contention",	KSTAT_DATA_UINT64 },
902 	{ "slab_alloc",		KSTAT_DATA_UINT64 },
903 	{ "slab_free",		KSTAT_DATA_UINT64 },
904 	{ "buf_constructed",	KSTAT_DATA_UINT64 },
905 	{ "buf_avail",		KSTAT_DATA_UINT64 },
906 	{ "buf_inuse",		KSTAT_DATA_UINT64 },
907 	{ "buf_total",		KSTAT_DATA_UINT64 },
908 	{ "buf_max",		KSTAT_DATA_UINT64 },
909 	{ "slab_create",	KSTAT_DATA_UINT64 },
910 	{ "slab_destroy",	KSTAT_DATA_UINT64 },
911 	{ "vmem_source",	KSTAT_DATA_UINT64 },
912 	{ "hash_size",		KSTAT_DATA_UINT64 },
913 	{ "hash_lookup_depth",	KSTAT_DATA_UINT64 },
914 	{ "hash_rescale",	KSTAT_DATA_UINT64 },
915 	{ "full_magazines",	KSTAT_DATA_UINT64 },
916 	{ "empty_magazines",	KSTAT_DATA_UINT64 },
917 	{ "magazine_size",	KSTAT_DATA_UINT64 },
918 	{ "reap",		KSTAT_DATA_UINT64 },
919 	{ "defrag",		KSTAT_DATA_UINT64 },
920 	{ "scan",		KSTAT_DATA_UINT64 },
921 	{ "move_callbacks",	KSTAT_DATA_UINT64 },
922 	{ "move_yes",		KSTAT_DATA_UINT64 },
923 	{ "move_no",		KSTAT_DATA_UINT64 },
924 	{ "move_later",		KSTAT_DATA_UINT64 },
925 	{ "move_dont_need",	KSTAT_DATA_UINT64 },
926 	{ "move_dont_know",	KSTAT_DATA_UINT64 },
927 	{ "move_hunt_found",	KSTAT_DATA_UINT64 },
928 	{ "move_slabs_freed",	KSTAT_DATA_UINT64 },
929 	{ "move_reclaimable",	KSTAT_DATA_UINT64 },
930 };
931 
932 static kmutex_t kmem_cache_kstat_lock;
933 
934 /*
935  * The default set of caches to back kmem_alloc().
936  * These sizes should be reevaluated periodically.
937  *
938  * We want allocations that are multiples of the coherency granularity
939  * (64 bytes) to be satisfied from a cache which is a multiple of 64
940  * bytes, so that it will be 64-byte aligned.  For all multiples of 64,
941  * the next kmem_cache_size greater than or equal to it must be a
942  * multiple of 64.
943  *
944  * We split the table into two sections:  size <= 4k and size > 4k.  This
945  * saves a lot of space and cache footprint in our cache tables.
946  */
947 static const int kmem_alloc_sizes[] = {
948 	1 * 8,
949 	2 * 8,
950 	3 * 8,
951 	4 * 8,		5 * 8,		6 * 8,		7 * 8,
952 	4 * 16,		5 * 16,		6 * 16,		7 * 16,
953 	4 * 32,		5 * 32,		6 * 32,		7 * 32,
954 	4 * 64,		5 * 64,		6 * 64,		7 * 64,
955 	4 * 128,	5 * 128,	6 * 128,	7 * 128,
956 	P2ALIGN(8192 / 7, 64),
957 	P2ALIGN(8192 / 6, 64),
958 	P2ALIGN(8192 / 5, 64),
959 	P2ALIGN(8192 / 4, 64),
960 	P2ALIGN(8192 / 3, 64),
961 	P2ALIGN(8192 / 2, 64),
962 };
963 
964 static const int kmem_big_alloc_sizes[] = {
965 	2 * 4096,	3 * 4096,
966 	2 * 8192,	3 * 8192,
967 	4 * 8192,	5 * 8192,	6 * 8192,	7 * 8192,
968 	8 * 8192,	9 * 8192,	10 * 8192,	11 * 8192,
969 	12 * 8192,	13 * 8192,	14 * 8192,	15 * 8192,
970 	16 * 8192
971 };
972 
973 #define	KMEM_MAXBUF		4096
974 #define	KMEM_BIG_MAXBUF_32BIT	32768
975 #define	KMEM_BIG_MAXBUF		131072
976 
977 #define	KMEM_BIG_MULTIPLE	4096	/* big_alloc_sizes must be a multiple */
978 #define	KMEM_BIG_SHIFT		12	/* lg(KMEM_BIG_MULTIPLE) */
979 
980 static kmem_cache_t *kmem_alloc_table[KMEM_MAXBUF >> KMEM_ALIGN_SHIFT];
981 static kmem_cache_t *kmem_big_alloc_table[KMEM_BIG_MAXBUF >> KMEM_BIG_SHIFT];
982 
983 #define	KMEM_ALLOC_TABLE_MAX	(KMEM_MAXBUF >> KMEM_ALIGN_SHIFT)
984 static size_t kmem_big_alloc_table_max = 0;	/* # of filled elements */
985 
986 static kmem_magtype_t kmem_magtype[] = {
987 	{ 1,	8,	3200,	65536	},
988 	{ 3,	16,	256,	32768	},
989 	{ 7,	32,	64,	16384	},
990 	{ 15,	64,	0,	8192	},
991 	{ 31,	64,	0,	4096	},
992 	{ 47,	64,	0,	2048	},
993 	{ 63,	64,	0,	1024	},
994 	{ 95,	64,	0,	512	},
995 	{ 143,	64,	0,	0	},
996 };
997 
998 static uint32_t kmem_reaping;
999 static uint32_t kmem_reaping_idspace;
1000 
1001 /*
1002  * kmem tunables
1003  */
1004 clock_t kmem_reap_interval;	/* cache reaping rate [15 * HZ ticks] */
1005 int kmem_depot_contention = 3;	/* max failed tryenters per real interval */
1006 pgcnt_t kmem_reapahead = 0;	/* start reaping N pages before pageout */
1007 int kmem_panic = 1;		/* whether to panic on error */
1008 int kmem_logging = 1;		/* kmem_log_enter() override */
1009 uint32_t kmem_mtbf = 0;		/* mean time between failures [default: off] */
1010 size_t kmem_transaction_log_size; /* transaction log size [2% of memory] */
1011 size_t kmem_content_log_size;	/* content log size [2% of memory] */
1012 size_t kmem_failure_log_size;	/* failure log [4 pages per CPU] */
1013 size_t kmem_slab_log_size;	/* slab create log [4 pages per CPU] */
1014 size_t kmem_zerosized_log_size;	/* zero-sized log [4 pages per CPU] */
1015 size_t kmem_content_maxsave = 256; /* KMF_CONTENTS max bytes to log */
1016 size_t kmem_lite_minsize = 0;	/* minimum buffer size for KMF_LITE */
1017 size_t kmem_lite_maxalign = 1024; /* maximum buffer alignment for KMF_LITE */
1018 int kmem_lite_pcs = 4;		/* number of PCs to store in KMF_LITE mode */
1019 size_t kmem_maxverify;		/* maximum bytes to inspect in debug routines */
1020 size_t kmem_minfirewall;	/* hardware-enforced redzone threshold */
1021 
1022 #ifdef DEBUG
1023 int kmem_warn_zerosized = 1;	/* whether to warn on zero-sized KM_SLEEP */
1024 #else
1025 int kmem_warn_zerosized = 0;	/* whether to warn on zero-sized KM_SLEEP */
1026 #endif
1027 
1028 int kmem_panic_zerosized = 0;	/* whether to panic on zero-sized KM_SLEEP */
1029 
1030 #ifdef _LP64
1031 size_t	kmem_max_cached = KMEM_BIG_MAXBUF;	/* maximum kmem_alloc cache */
1032 #else
1033 size_t	kmem_max_cached = KMEM_BIG_MAXBUF_32BIT; /* maximum kmem_alloc cache */
1034 #endif
1035 
1036 #ifdef DEBUG
1037 int kmem_flags = KMF_AUDIT | KMF_DEADBEEF | KMF_REDZONE | KMF_CONTENTS;
1038 #else
1039 int kmem_flags = 0;
1040 #endif
1041 int kmem_ready;
1042 
1043 static kmem_cache_t	*kmem_slab_cache;
1044 static kmem_cache_t	*kmem_bufctl_cache;
1045 static kmem_cache_t	*kmem_bufctl_audit_cache;
1046 
1047 static kmutex_t		kmem_cache_lock;	/* inter-cache linkage only */
1048 static list_t		kmem_caches;
1049 
1050 static taskq_t		*kmem_taskq;
1051 static kmutex_t		kmem_flags_lock;
1052 static vmem_t		*kmem_metadata_arena;
1053 static vmem_t		*kmem_msb_arena;	/* arena for metadata caches */
1054 static vmem_t		*kmem_cache_arena;
1055 static vmem_t		*kmem_hash_arena;
1056 static vmem_t		*kmem_log_arena;
1057 static vmem_t		*kmem_oversize_arena;
1058 static vmem_t		*kmem_va_arena;
1059 static vmem_t		*kmem_default_arena;
1060 static vmem_t		*kmem_firewall_va_arena;
1061 static vmem_t		*kmem_firewall_arena;
1062 
1063 static int		kmem_zerosized;		/* # of zero-sized allocs */
1064 
1065 /*
1066  * kmem slab consolidator thresholds (tunables)
1067  */
1068 size_t kmem_frag_minslabs = 101;	/* minimum total slabs */
1069 size_t kmem_frag_numer = 1;		/* free buffers (numerator) */
1070 size_t kmem_frag_denom = KMEM_VOID_FRACTION; /* buffers (denominator) */
1071 /*
1072  * Maximum number of slabs from which to move buffers during a single
1073  * maintenance interval while the system is not low on memory.
1074  */
1075 size_t kmem_reclaim_max_slabs = 1;
1076 /*
1077  * Number of slabs to scan backwards from the end of the partial slab list
1078  * when searching for buffers to relocate.
1079  */
1080 size_t kmem_reclaim_scan_range = 12;
1081 
1082 /* consolidator knobs */
1083 boolean_t kmem_move_noreap;
1084 boolean_t kmem_move_blocked;
1085 boolean_t kmem_move_fulltilt;
1086 boolean_t kmem_move_any_partial;
1087 
1088 #ifdef	DEBUG
1089 /*
1090  * kmem consolidator debug tunables:
1091  * Ensure code coverage by occasionally running the consolidator even when the
1092  * caches are not fragmented (they may never be). These intervals are mean time
1093  * in cache maintenance intervals (kmem_cache_update).
1094  */
1095 uint32_t kmem_mtb_move = 60;	/* defrag 1 slab (~15min) */
1096 uint32_t kmem_mtb_reap = 1800;	/* defrag all slabs (~7.5hrs) */
1097 #endif	/* DEBUG */
1098 
1099 static kmem_cache_t	*kmem_defrag_cache;
1100 static kmem_cache_t	*kmem_move_cache;
1101 static taskq_t		*kmem_move_taskq;
1102 
1103 static void kmem_cache_scan(kmem_cache_t *);
1104 static void kmem_cache_defrag(kmem_cache_t *);
1105 static void kmem_slab_prefill(kmem_cache_t *, kmem_slab_t *);
1106 
1107 
1108 kmem_log_header_t	*kmem_transaction_log;
1109 kmem_log_header_t	*kmem_content_log;
1110 kmem_log_header_t	*kmem_failure_log;
1111 kmem_log_header_t	*kmem_slab_log;
1112 kmem_log_header_t	*kmem_zerosized_log;
1113 
1114 static int		kmem_lite_count; /* # of PCs in kmem_buftag_lite_t */
1115 
1116 #define	KMEM_BUFTAG_LITE_ENTER(bt, count, caller)			\
1117 	if ((count) > 0) {						\
1118 		pc_t *_s = ((kmem_buftag_lite_t *)(bt))->bt_history;	\
1119 		pc_t *_e;						\
1120 		/* memmove() the old entries down one notch */		\
1121 		for (_e = &_s[(count) - 1]; _e > _s; _e--)		\
1122 			*_e = *(_e - 1);				\
1123 		*_s = (uintptr_t)(caller);				\
1124 	}
1125 
1126 #define	KMERR_MODIFIED	0	/* buffer modified while on freelist */
1127 #define	KMERR_REDZONE	1	/* redzone violation (write past end of buf) */
1128 #define	KMERR_DUPFREE	2	/* freed a buffer twice */
1129 #define	KMERR_BADADDR	3	/* freed a bad (unallocated) address */
1130 #define	KMERR_BADBUFTAG	4	/* buftag corrupted */
1131 #define	KMERR_BADBUFCTL	5	/* bufctl corrupted */
1132 #define	KMERR_BADCACHE	6	/* freed a buffer to the wrong cache */
1133 #define	KMERR_BADSIZE	7	/* alloc size != free size */
1134 #define	KMERR_BADBASE	8	/* buffer base address wrong */
1135 
1136 struct {
1137 	hrtime_t	kmp_timestamp;	/* timestamp of panic */
1138 	int		kmp_error;	/* type of kmem error */
1139 	void		*kmp_buffer;	/* buffer that induced panic */
1140 	void		*kmp_realbuf;	/* real start address for buffer */
1141 	kmem_cache_t	*kmp_cache;	/* buffer's cache according to client */
1142 	kmem_cache_t	*kmp_realcache;	/* actual cache containing buffer */
1143 	kmem_slab_t	*kmp_slab;	/* slab accoring to kmem_findslab() */
1144 	kmem_bufctl_t	*kmp_bufctl;	/* bufctl */
1145 } kmem_panic_info;
1146 
1147 
1148 static void
1149 copy_pattern(uint64_t pattern, void *buf_arg, size_t size)
1150 {
1151 	uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1152 	uint64_t *buf = buf_arg;
1153 
1154 	while (buf < bufend)
1155 		*buf++ = pattern;
1156 }
1157 
1158 static void *
1159 verify_pattern(uint64_t pattern, void *buf_arg, size_t size)
1160 {
1161 	uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1162 	uint64_t *buf;
1163 
1164 	for (buf = buf_arg; buf < bufend; buf++)
1165 		if (*buf != pattern)
1166 			return (buf);
1167 	return (NULL);
1168 }
1169 
1170 static void *
1171 verify_and_copy_pattern(uint64_t old, uint64_t new, void *buf_arg, size_t size)
1172 {
1173 	uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1174 	uint64_t *buf;
1175 
1176 	for (buf = buf_arg; buf < bufend; buf++) {
1177 		if (*buf != old) {
1178 			copy_pattern(old, buf_arg,
1179 			    (char *)buf - (char *)buf_arg);
1180 			return (buf);
1181 		}
1182 		*buf = new;
1183 	}
1184 
1185 	return (NULL);
1186 }
1187 
1188 static void
1189 kmem_cache_applyall(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1190 {
1191 	kmem_cache_t *cp;
1192 
1193 	mutex_enter(&kmem_cache_lock);
1194 	for (cp = list_head(&kmem_caches); cp != NULL;
1195 	    cp = list_next(&kmem_caches, cp))
1196 		if (tq != NULL)
1197 			(void) taskq_dispatch(tq, (task_func_t *)func, cp,
1198 			    tqflag);
1199 		else
1200 			func(cp);
1201 	mutex_exit(&kmem_cache_lock);
1202 }
1203 
1204 static void
1205 kmem_cache_applyall_id(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1206 {
1207 	kmem_cache_t *cp;
1208 
1209 	mutex_enter(&kmem_cache_lock);
1210 	for (cp = list_head(&kmem_caches); cp != NULL;
1211 	    cp = list_next(&kmem_caches, cp)) {
1212 		if (!(cp->cache_cflags & KMC_IDENTIFIER))
1213 			continue;
1214 		if (tq != NULL)
1215 			(void) taskq_dispatch(tq, (task_func_t *)func, cp,
1216 			    tqflag);
1217 		else
1218 			func(cp);
1219 	}
1220 	mutex_exit(&kmem_cache_lock);
1221 }
1222 
1223 /*
1224  * Debugging support.  Given a buffer address, find its slab.
1225  */
1226 static kmem_slab_t *
1227 kmem_findslab(kmem_cache_t *cp, void *buf)
1228 {
1229 	kmem_slab_t *sp;
1230 
1231 	mutex_enter(&cp->cache_lock);
1232 	for (sp = list_head(&cp->cache_complete_slabs); sp != NULL;
1233 	    sp = list_next(&cp->cache_complete_slabs, sp)) {
1234 		if (KMEM_SLAB_MEMBER(sp, buf)) {
1235 			mutex_exit(&cp->cache_lock);
1236 			return (sp);
1237 		}
1238 	}
1239 	for (sp = avl_first(&cp->cache_partial_slabs); sp != NULL;
1240 	    sp = AVL_NEXT(&cp->cache_partial_slabs, sp)) {
1241 		if (KMEM_SLAB_MEMBER(sp, buf)) {
1242 			mutex_exit(&cp->cache_lock);
1243 			return (sp);
1244 		}
1245 	}
1246 	mutex_exit(&cp->cache_lock);
1247 
1248 	return (NULL);
1249 }
1250 
1251 static void
1252 kmem_error(int error, kmem_cache_t *cparg, void *bufarg)
1253 {
1254 	kmem_buftag_t *btp = NULL;
1255 	kmem_bufctl_t *bcp = NULL;
1256 	kmem_cache_t *cp = cparg;
1257 	kmem_slab_t *sp;
1258 	uint64_t *off;
1259 	void *buf = bufarg;
1260 
1261 	kmem_logging = 0;	/* stop logging when a bad thing happens */
1262 
1263 	kmem_panic_info.kmp_timestamp = gethrtime();
1264 
1265 	sp = kmem_findslab(cp, buf);
1266 	if (sp == NULL) {
1267 		for (cp = list_tail(&kmem_caches); cp != NULL;
1268 		    cp = list_prev(&kmem_caches, cp)) {
1269 			if ((sp = kmem_findslab(cp, buf)) != NULL)
1270 				break;
1271 		}
1272 	}
1273 
1274 	if (sp == NULL) {
1275 		cp = NULL;
1276 		error = KMERR_BADADDR;
1277 	} else {
1278 		if (cp != cparg)
1279 			error = KMERR_BADCACHE;
1280 		else
1281 			buf = (char *)bufarg - ((uintptr_t)bufarg -
1282 			    (uintptr_t)sp->slab_base) % cp->cache_chunksize;
1283 		if (buf != bufarg)
1284 			error = KMERR_BADBASE;
1285 		if (cp->cache_flags & KMF_BUFTAG)
1286 			btp = KMEM_BUFTAG(cp, buf);
1287 		if (cp->cache_flags & KMF_HASH) {
1288 			mutex_enter(&cp->cache_lock);
1289 			for (bcp = *KMEM_HASH(cp, buf); bcp; bcp = bcp->bc_next)
1290 				if (bcp->bc_addr == buf)
1291 					break;
1292 			mutex_exit(&cp->cache_lock);
1293 			if (bcp == NULL && btp != NULL)
1294 				bcp = btp->bt_bufctl;
1295 			if (kmem_findslab(cp->cache_bufctl_cache, bcp) ==
1296 			    NULL || P2PHASE((uintptr_t)bcp, KMEM_ALIGN) ||
1297 			    bcp->bc_addr != buf) {
1298 				error = KMERR_BADBUFCTL;
1299 				bcp = NULL;
1300 			}
1301 		}
1302 	}
1303 
1304 	kmem_panic_info.kmp_error = error;
1305 	kmem_panic_info.kmp_buffer = bufarg;
1306 	kmem_panic_info.kmp_realbuf = buf;
1307 	kmem_panic_info.kmp_cache = cparg;
1308 	kmem_panic_info.kmp_realcache = cp;
1309 	kmem_panic_info.kmp_slab = sp;
1310 	kmem_panic_info.kmp_bufctl = bcp;
1311 
1312 	printf("kernel memory allocator: ");
1313 
1314 	switch (error) {
1315 
1316 	case KMERR_MODIFIED:
1317 		printf("buffer modified after being freed\n");
1318 		off = verify_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1319 		if (off == NULL)	/* shouldn't happen */
1320 			off = buf;
1321 		printf("modification occurred at offset 0x%lx "
1322 		    "(0x%llx replaced by 0x%llx)\n",
1323 		    (uintptr_t)off - (uintptr_t)buf,
1324 		    (longlong_t)KMEM_FREE_PATTERN, (longlong_t)*off);
1325 		break;
1326 
1327 	case KMERR_REDZONE:
1328 		printf("redzone violation: write past end of buffer\n");
1329 		break;
1330 
1331 	case KMERR_BADADDR:
1332 		printf("invalid free: buffer not in cache\n");
1333 		break;
1334 
1335 	case KMERR_DUPFREE:
1336 		printf("duplicate free: buffer freed twice\n");
1337 		break;
1338 
1339 	case KMERR_BADBUFTAG:
1340 		printf("boundary tag corrupted\n");
1341 		printf("bcp ^ bxstat = %lx, should be %lx\n",
1342 		    (intptr_t)btp->bt_bufctl ^ btp->bt_bxstat,
1343 		    KMEM_BUFTAG_FREE);
1344 		break;
1345 
1346 	case KMERR_BADBUFCTL:
1347 		printf("bufctl corrupted\n");
1348 		break;
1349 
1350 	case KMERR_BADCACHE:
1351 		printf("buffer freed to wrong cache\n");
1352 		printf("buffer was allocated from %s,\n", cp->cache_name);
1353 		printf("caller attempting free to %s.\n", cparg->cache_name);
1354 		break;
1355 
1356 	case KMERR_BADSIZE:
1357 		printf("bad free: free size (%u) != alloc size (%u)\n",
1358 		    KMEM_SIZE_DECODE(((uint32_t *)btp)[0]),
1359 		    KMEM_SIZE_DECODE(((uint32_t *)btp)[1]));
1360 		break;
1361 
1362 	case KMERR_BADBASE:
1363 		printf("bad free: free address (%p) != alloc address (%p)\n",
1364 		    bufarg, buf);
1365 		break;
1366 	}
1367 
1368 	printf("buffer=%p  bufctl=%p  cache: %s\n",
1369 	    bufarg, (void *)bcp, cparg->cache_name);
1370 
1371 	if (bcp != NULL && (cp->cache_flags & KMF_AUDIT) &&
1372 	    error != KMERR_BADBUFCTL) {
1373 		int d;
1374 		timestruc_t ts;
1375 		kmem_bufctl_audit_t *bcap = (kmem_bufctl_audit_t *)bcp;
1376 
1377 		hrt2ts(kmem_panic_info.kmp_timestamp - bcap->bc_timestamp, &ts);
1378 		printf("previous transaction on buffer %p:\n", buf);
1379 		printf("thread=%p  time=T-%ld.%09ld  slab=%p  cache: %s\n",
1380 		    (void *)bcap->bc_thread, ts.tv_sec, ts.tv_nsec,
1381 		    (void *)sp, cp->cache_name);
1382 		for (d = 0; d < MIN(bcap->bc_depth, KMEM_STACK_DEPTH); d++) {
1383 			ulong_t off;
1384 			char *sym = kobj_getsymname(bcap->bc_stack[d], &off);
1385 			printf("%s+%lx\n", sym ? sym : "?", off);
1386 		}
1387 	}
1388 	if (kmem_panic > 0)
1389 		panic("kernel heap corruption detected");
1390 	if (kmem_panic == 0)
1391 		debug_enter(NULL);
1392 	kmem_logging = 1;	/* resume logging */
1393 }
1394 
1395 static kmem_log_header_t *
1396 kmem_log_init(size_t logsize)
1397 {
1398 	kmem_log_header_t *lhp;
1399 	int nchunks = 4 * max_ncpus;
1400 	size_t lhsize = (size_t)&((kmem_log_header_t *)0)->lh_cpu[max_ncpus];
1401 	int i;
1402 
1403 	/*
1404 	 * Make sure that lhp->lh_cpu[] is nicely aligned
1405 	 * to prevent false sharing of cache lines.
1406 	 */
1407 	lhsize = P2ROUNDUP(lhsize, KMEM_ALIGN);
1408 	lhp = vmem_xalloc(kmem_log_arena, lhsize, 64, P2NPHASE(lhsize, 64), 0,
1409 	    NULL, NULL, VM_SLEEP);
1410 	bzero(lhp, lhsize);
1411 
1412 	mutex_init(&lhp->lh_lock, NULL, MUTEX_DEFAULT, NULL);
1413 	lhp->lh_nchunks = nchunks;
1414 	lhp->lh_chunksize = P2ROUNDUP(logsize / nchunks + 1, PAGESIZE);
1415 	lhp->lh_base = vmem_alloc(kmem_log_arena,
1416 	    lhp->lh_chunksize * nchunks, VM_SLEEP);
1417 	lhp->lh_free = vmem_alloc(kmem_log_arena,
1418 	    nchunks * sizeof (int), VM_SLEEP);
1419 	bzero(lhp->lh_base, lhp->lh_chunksize * nchunks);
1420 
1421 	for (i = 0; i < max_ncpus; i++) {
1422 		kmem_cpu_log_header_t *clhp = &lhp->lh_cpu[i];
1423 		mutex_init(&clhp->clh_lock, NULL, MUTEX_DEFAULT, NULL);
1424 		clhp->clh_chunk = i;
1425 	}
1426 
1427 	for (i = max_ncpus; i < nchunks; i++)
1428 		lhp->lh_free[i] = i;
1429 
1430 	lhp->lh_head = max_ncpus;
1431 	lhp->lh_tail = 0;
1432 
1433 	return (lhp);
1434 }
1435 
1436 static void *
1437 kmem_log_enter(kmem_log_header_t *lhp, void *data, size_t size)
1438 {
1439 	void *logspace;
1440 	kmem_cpu_log_header_t *clhp;
1441 
1442 	if (lhp == NULL || kmem_logging == 0 || panicstr)
1443 		return (NULL);
1444 
1445 	clhp = &lhp->lh_cpu[CPU->cpu_seqid];
1446 
1447 	mutex_enter(&clhp->clh_lock);
1448 	clhp->clh_hits++;
1449 	if (size > clhp->clh_avail) {
1450 		mutex_enter(&lhp->lh_lock);
1451 		lhp->lh_hits++;
1452 		lhp->lh_free[lhp->lh_tail] = clhp->clh_chunk;
1453 		lhp->lh_tail = (lhp->lh_tail + 1) % lhp->lh_nchunks;
1454 		clhp->clh_chunk = lhp->lh_free[lhp->lh_head];
1455 		lhp->lh_head = (lhp->lh_head + 1) % lhp->lh_nchunks;
1456 		clhp->clh_current = lhp->lh_base +
1457 		    clhp->clh_chunk * lhp->lh_chunksize;
1458 		clhp->clh_avail = lhp->lh_chunksize;
1459 		if (size > lhp->lh_chunksize)
1460 			size = lhp->lh_chunksize;
1461 		mutex_exit(&lhp->lh_lock);
1462 	}
1463 	logspace = clhp->clh_current;
1464 	clhp->clh_current += size;
1465 	clhp->clh_avail -= size;
1466 	bcopy(data, logspace, size);
1467 	mutex_exit(&clhp->clh_lock);
1468 	return (logspace);
1469 }
1470 
1471 #define	KMEM_AUDIT(lp, cp, bcp)						\
1472 {									\
1473 	kmem_bufctl_audit_t *_bcp = (kmem_bufctl_audit_t *)(bcp);	\
1474 	_bcp->bc_timestamp = gethrtime();				\
1475 	_bcp->bc_thread = curthread;					\
1476 	_bcp->bc_depth = getpcstack(_bcp->bc_stack, KMEM_STACK_DEPTH);	\
1477 	_bcp->bc_lastlog = kmem_log_enter((lp), _bcp, sizeof (*_bcp));	\
1478 }
1479 
1480 static void
1481 kmem_log_event(kmem_log_header_t *lp, kmem_cache_t *cp,
1482     kmem_slab_t *sp, void *addr)
1483 {
1484 	kmem_bufctl_audit_t bca;
1485 
1486 	bzero(&bca, sizeof (kmem_bufctl_audit_t));
1487 	bca.bc_addr = addr;
1488 	bca.bc_slab = sp;
1489 	bca.bc_cache = cp;
1490 	KMEM_AUDIT(lp, cp, &bca);
1491 }
1492 
1493 /*
1494  * Create a new slab for cache cp.
1495  */
1496 static kmem_slab_t *
1497 kmem_slab_create(kmem_cache_t *cp, int kmflag)
1498 {
1499 	size_t slabsize = cp->cache_slabsize;
1500 	size_t chunksize = cp->cache_chunksize;
1501 	int cache_flags = cp->cache_flags;
1502 	size_t color, chunks;
1503 	char *buf, *slab;
1504 	kmem_slab_t *sp;
1505 	kmem_bufctl_t *bcp;
1506 	vmem_t *vmp = cp->cache_arena;
1507 
1508 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1509 
1510 	color = cp->cache_color + cp->cache_align;
1511 	if (color > cp->cache_maxcolor)
1512 		color = cp->cache_mincolor;
1513 	cp->cache_color = color;
1514 
1515 	slab = vmem_alloc(vmp, slabsize, kmflag & KM_VMFLAGS);
1516 
1517 	if (slab == NULL)
1518 		goto vmem_alloc_failure;
1519 
1520 	ASSERT(P2PHASE((uintptr_t)slab, vmp->vm_quantum) == 0);
1521 
1522 	/*
1523 	 * Reverify what was already checked in kmem_cache_set_move(), since the
1524 	 * consolidator depends (for correctness) on slabs being initialized
1525 	 * with the 0xbaddcafe memory pattern (setting a low order bit usable by
1526 	 * clients to distinguish uninitialized memory from known objects).
1527 	 */
1528 	ASSERT((cp->cache_move == NULL) || !(cp->cache_cflags & KMC_NOTOUCH));
1529 	if (!(cp->cache_cflags & KMC_NOTOUCH))
1530 		copy_pattern(KMEM_UNINITIALIZED_PATTERN, slab, slabsize);
1531 
1532 	if (cache_flags & KMF_HASH) {
1533 		if ((sp = kmem_cache_alloc(kmem_slab_cache, kmflag)) == NULL)
1534 			goto slab_alloc_failure;
1535 		chunks = (slabsize - color) / chunksize;
1536 	} else {
1537 		sp = KMEM_SLAB(cp, slab);
1538 		chunks = (slabsize - sizeof (kmem_slab_t) - color) / chunksize;
1539 	}
1540 
1541 	sp->slab_cache	= cp;
1542 	sp->slab_head	= NULL;
1543 	sp->slab_refcnt	= 0;
1544 	sp->slab_base	= buf = slab + color;
1545 	sp->slab_chunks	= chunks;
1546 	sp->slab_stuck_offset = (uint32_t)-1;
1547 	sp->slab_later_count = 0;
1548 	sp->slab_flags = 0;
1549 
1550 	ASSERT(chunks > 0);
1551 	while (chunks-- != 0) {
1552 		if (cache_flags & KMF_HASH) {
1553 			bcp = kmem_cache_alloc(cp->cache_bufctl_cache, kmflag);
1554 			if (bcp == NULL)
1555 				goto bufctl_alloc_failure;
1556 			if (cache_flags & KMF_AUDIT) {
1557 				kmem_bufctl_audit_t *bcap =
1558 				    (kmem_bufctl_audit_t *)bcp;
1559 				bzero(bcap, sizeof (kmem_bufctl_audit_t));
1560 				bcap->bc_cache = cp;
1561 			}
1562 			bcp->bc_addr = buf;
1563 			bcp->bc_slab = sp;
1564 		} else {
1565 			bcp = KMEM_BUFCTL(cp, buf);
1566 		}
1567 		if (cache_flags & KMF_BUFTAG) {
1568 			kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1569 			btp->bt_redzone = KMEM_REDZONE_PATTERN;
1570 			btp->bt_bufctl = bcp;
1571 			btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1572 			if (cache_flags & KMF_DEADBEEF) {
1573 				copy_pattern(KMEM_FREE_PATTERN, buf,
1574 				    cp->cache_verify);
1575 			}
1576 		}
1577 		bcp->bc_next = sp->slab_head;
1578 		sp->slab_head = bcp;
1579 		buf += chunksize;
1580 	}
1581 
1582 	kmem_log_event(kmem_slab_log, cp, sp, slab);
1583 
1584 	return (sp);
1585 
1586 bufctl_alloc_failure:
1587 
1588 	while ((bcp = sp->slab_head) != NULL) {
1589 		sp->slab_head = bcp->bc_next;
1590 		kmem_cache_free(cp->cache_bufctl_cache, bcp);
1591 	}
1592 	kmem_cache_free(kmem_slab_cache, sp);
1593 
1594 slab_alloc_failure:
1595 
1596 	vmem_free(vmp, slab, slabsize);
1597 
1598 vmem_alloc_failure:
1599 
1600 	kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1601 	atomic_inc_64(&cp->cache_alloc_fail);
1602 
1603 	return (NULL);
1604 }
1605 
1606 /*
1607  * Destroy a slab.
1608  */
1609 static void
1610 kmem_slab_destroy(kmem_cache_t *cp, kmem_slab_t *sp)
1611 {
1612 	vmem_t *vmp = cp->cache_arena;
1613 	void *slab = (void *)P2ALIGN((uintptr_t)sp->slab_base, vmp->vm_quantum);
1614 
1615 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1616 	ASSERT(sp->slab_refcnt == 0);
1617 
1618 	if (cp->cache_flags & KMF_HASH) {
1619 		kmem_bufctl_t *bcp;
1620 		while ((bcp = sp->slab_head) != NULL) {
1621 			sp->slab_head = bcp->bc_next;
1622 			kmem_cache_free(cp->cache_bufctl_cache, bcp);
1623 		}
1624 		kmem_cache_free(kmem_slab_cache, sp);
1625 	}
1626 	vmem_free(vmp, slab, cp->cache_slabsize);
1627 }
1628 
1629 static void *
1630 kmem_slab_alloc_impl(kmem_cache_t *cp, kmem_slab_t *sp, boolean_t prefill)
1631 {
1632 	kmem_bufctl_t *bcp, **hash_bucket;
1633 	void *buf;
1634 	boolean_t new_slab = (sp->slab_refcnt == 0);
1635 
1636 	ASSERT(MUTEX_HELD(&cp->cache_lock));
1637 	/*
1638 	 * kmem_slab_alloc() drops cache_lock when it creates a new slab, so we
1639 	 * can't ASSERT(avl_is_empty(&cp->cache_partial_slabs)) here when the
1640 	 * slab is newly created.
1641 	 */
1642 	ASSERT(new_slab || (KMEM_SLAB_IS_PARTIAL(sp) &&
1643 	    (sp == avl_first(&cp->cache_partial_slabs))));
1644 	ASSERT(sp->slab_cache == cp);
1645 
1646 	cp->cache_slab_alloc++;
1647 	cp->cache_bufslab--;
1648 	sp->slab_refcnt++;
1649 
1650 	bcp = sp->slab_head;
1651 	sp->slab_head = bcp->bc_next;
1652 
1653 	if (cp->cache_flags & KMF_HASH) {
1654 		/*
1655 		 * Add buffer to allocated-address hash table.
1656 		 */
1657 		buf = bcp->bc_addr;
1658 		hash_bucket = KMEM_HASH(cp, buf);
1659 		bcp->bc_next = *hash_bucket;
1660 		*hash_bucket = bcp;
1661 		if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1662 			KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1663 		}
1664 	} else {
1665 		buf = KMEM_BUF(cp, bcp);
1666 	}
1667 
1668 	ASSERT(KMEM_SLAB_MEMBER(sp, buf));
1669 
1670 	if (sp->slab_head == NULL) {
1671 		ASSERT(KMEM_SLAB_IS_ALL_USED(sp));
1672 		if (new_slab) {
1673 			ASSERT(sp->slab_chunks == 1);
1674 		} else {
1675 			ASSERT(sp->slab_chunks > 1); /* the slab was partial */
1676 			avl_remove(&cp->cache_partial_slabs, sp);
1677 			sp->slab_later_count = 0; /* clear history */
1678 			sp->slab_flags &= ~KMEM_SLAB_NOMOVE;
1679 			sp->slab_stuck_offset = (uint32_t)-1;
1680 		}
1681 		list_insert_head(&cp->cache_complete_slabs, sp);
1682 		cp->cache_complete_slab_count++;
1683 		return (buf);
1684 	}
1685 
1686 	ASSERT(KMEM_SLAB_IS_PARTIAL(sp));
1687 	/*
1688 	 * Peek to see if the magazine layer is enabled before
1689 	 * we prefill.  We're not holding the cpu cache lock,
1690 	 * so the peek could be wrong, but there's no harm in it.
1691 	 */
1692 	if (new_slab && prefill && (cp->cache_flags & KMF_PREFILL) &&
1693 	    (KMEM_CPU_CACHE(cp)->cc_magsize != 0))  {
1694 		kmem_slab_prefill(cp, sp);
1695 		return (buf);
1696 	}
1697 
1698 	if (new_slab) {
1699 		avl_add(&cp->cache_partial_slabs, sp);
1700 		return (buf);
1701 	}
1702 
1703 	/*
1704 	 * The slab is now more allocated than it was, so the
1705 	 * order remains unchanged.
1706 	 */
1707 	ASSERT(!avl_update(&cp->cache_partial_slabs, sp));
1708 	return (buf);
1709 }
1710 
1711 /*
1712  * Allocate a raw (unconstructed) buffer from cp's slab layer.
1713  */
1714 static void *
1715 kmem_slab_alloc(kmem_cache_t *cp, int kmflag)
1716 {
1717 	kmem_slab_t *sp;
1718 	void *buf;
1719 	boolean_t test_destructor;
1720 
1721 	mutex_enter(&cp->cache_lock);
1722 	test_destructor = (cp->cache_slab_alloc == 0);
1723 	sp = avl_first(&cp->cache_partial_slabs);
1724 	if (sp == NULL) {
1725 		ASSERT(cp->cache_bufslab == 0);
1726 
1727 		/*
1728 		 * The freelist is empty.  Create a new slab.
1729 		 */
1730 		mutex_exit(&cp->cache_lock);
1731 		if ((sp = kmem_slab_create(cp, kmflag)) == NULL) {
1732 			return (NULL);
1733 		}
1734 		mutex_enter(&cp->cache_lock);
1735 		cp->cache_slab_create++;
1736 		if ((cp->cache_buftotal += sp->slab_chunks) > cp->cache_bufmax)
1737 			cp->cache_bufmax = cp->cache_buftotal;
1738 		cp->cache_bufslab += sp->slab_chunks;
1739 	}
1740 
1741 	buf = kmem_slab_alloc_impl(cp, sp, B_TRUE);
1742 	ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1743 	    (cp->cache_complete_slab_count +
1744 	    avl_numnodes(&cp->cache_partial_slabs) +
1745 	    (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1746 	mutex_exit(&cp->cache_lock);
1747 
1748 	if (test_destructor && cp->cache_destructor != NULL) {
1749 		/*
1750 		 * On the first kmem_slab_alloc(), assert that it is valid to
1751 		 * call the destructor on a newly constructed object without any
1752 		 * client involvement.
1753 		 */
1754 		if ((cp->cache_constructor == NULL) ||
1755 		    cp->cache_constructor(buf, cp->cache_private,
1756 		    kmflag) == 0) {
1757 			cp->cache_destructor(buf, cp->cache_private);
1758 		}
1759 		copy_pattern(KMEM_UNINITIALIZED_PATTERN, buf,
1760 		    cp->cache_bufsize);
1761 		if (cp->cache_flags & KMF_DEADBEEF) {
1762 			copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1763 		}
1764 	}
1765 
1766 	return (buf);
1767 }
1768 
1769 static void kmem_slab_move_yes(kmem_cache_t *, kmem_slab_t *, void *);
1770 
1771 /*
1772  * Free a raw (unconstructed) buffer to cp's slab layer.
1773  */
1774 static void
1775 kmem_slab_free(kmem_cache_t *cp, void *buf)
1776 {
1777 	kmem_slab_t *sp;
1778 	kmem_bufctl_t *bcp, **prev_bcpp;
1779 
1780 	ASSERT(buf != NULL);
1781 
1782 	mutex_enter(&cp->cache_lock);
1783 	cp->cache_slab_free++;
1784 
1785 	if (cp->cache_flags & KMF_HASH) {
1786 		/*
1787 		 * Look up buffer in allocated-address hash table.
1788 		 */
1789 		prev_bcpp = KMEM_HASH(cp, buf);
1790 		while ((bcp = *prev_bcpp) != NULL) {
1791 			if (bcp->bc_addr == buf) {
1792 				*prev_bcpp = bcp->bc_next;
1793 				sp = bcp->bc_slab;
1794 				break;
1795 			}
1796 			cp->cache_lookup_depth++;
1797 			prev_bcpp = &bcp->bc_next;
1798 		}
1799 	} else {
1800 		bcp = KMEM_BUFCTL(cp, buf);
1801 		sp = KMEM_SLAB(cp, buf);
1802 	}
1803 
1804 	if (bcp == NULL || sp->slab_cache != cp || !KMEM_SLAB_MEMBER(sp, buf)) {
1805 		mutex_exit(&cp->cache_lock);
1806 		kmem_error(KMERR_BADADDR, cp, buf);
1807 		return;
1808 	}
1809 
1810 	if (KMEM_SLAB_OFFSET(sp, buf) == sp->slab_stuck_offset) {
1811 		/*
1812 		 * If this is the buffer that prevented the consolidator from
1813 		 * clearing the slab, we can reset the slab flags now that the
1814 		 * buffer is freed. (It makes sense to do this in
1815 		 * kmem_cache_free(), where the client gives up ownership of the
1816 		 * buffer, but on the hot path the test is too expensive.)
1817 		 */
1818 		kmem_slab_move_yes(cp, sp, buf);
1819 	}
1820 
1821 	if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1822 		if (cp->cache_flags & KMF_CONTENTS)
1823 			((kmem_bufctl_audit_t *)bcp)->bc_contents =
1824 			    kmem_log_enter(kmem_content_log, buf,
1825 			    cp->cache_contents);
1826 		KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1827 	}
1828 
1829 	bcp->bc_next = sp->slab_head;
1830 	sp->slab_head = bcp;
1831 
1832 	cp->cache_bufslab++;
1833 	ASSERT(sp->slab_refcnt >= 1);
1834 
1835 	if (--sp->slab_refcnt == 0) {
1836 		/*
1837 		 * There are no outstanding allocations from this slab,
1838 		 * so we can reclaim the memory.
1839 		 */
1840 		if (sp->slab_chunks == 1) {
1841 			list_remove(&cp->cache_complete_slabs, sp);
1842 			cp->cache_complete_slab_count--;
1843 		} else {
1844 			avl_remove(&cp->cache_partial_slabs, sp);
1845 		}
1846 
1847 		cp->cache_buftotal -= sp->slab_chunks;
1848 		cp->cache_bufslab -= sp->slab_chunks;
1849 		/*
1850 		 * Defer releasing the slab to the virtual memory subsystem
1851 		 * while there is a pending move callback, since we guarantee
1852 		 * that buffers passed to the move callback have only been
1853 		 * touched by kmem or by the client itself. Since the memory
1854 		 * patterns baddcafe (uninitialized) and deadbeef (freed) both
1855 		 * set at least one of the two lowest order bits, the client can
1856 		 * test those bits in the move callback to determine whether or
1857 		 * not it knows about the buffer (assuming that the client also
1858 		 * sets one of those low order bits whenever it frees a buffer).
1859 		 */
1860 		if (cp->cache_defrag == NULL ||
1861 		    (avl_is_empty(&cp->cache_defrag->kmd_moves_pending) &&
1862 		    !(sp->slab_flags & KMEM_SLAB_MOVE_PENDING))) {
1863 			cp->cache_slab_destroy++;
1864 			mutex_exit(&cp->cache_lock);
1865 			kmem_slab_destroy(cp, sp);
1866 		} else {
1867 			list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
1868 			/*
1869 			 * Slabs are inserted at both ends of the deadlist to
1870 			 * distinguish between slabs freed while move callbacks
1871 			 * are pending (list head) and a slab freed while the
1872 			 * lock is dropped in kmem_move_buffers() (list tail) so
1873 			 * that in both cases slab_destroy() is called from the
1874 			 * right context.
1875 			 */
1876 			if (sp->slab_flags & KMEM_SLAB_MOVE_PENDING) {
1877 				list_insert_tail(deadlist, sp);
1878 			} else {
1879 				list_insert_head(deadlist, sp);
1880 			}
1881 			cp->cache_defrag->kmd_deadcount++;
1882 			mutex_exit(&cp->cache_lock);
1883 		}
1884 		return;
1885 	}
1886 
1887 	if (bcp->bc_next == NULL) {
1888 		/* Transition the slab from completely allocated to partial. */
1889 		ASSERT(sp->slab_refcnt == (sp->slab_chunks - 1));
1890 		ASSERT(sp->slab_chunks > 1);
1891 		list_remove(&cp->cache_complete_slabs, sp);
1892 		cp->cache_complete_slab_count--;
1893 		avl_add(&cp->cache_partial_slabs, sp);
1894 	} else {
1895 		(void) avl_update_gt(&cp->cache_partial_slabs, sp);
1896 	}
1897 
1898 	ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1899 	    (cp->cache_complete_slab_count +
1900 	    avl_numnodes(&cp->cache_partial_slabs) +
1901 	    (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1902 	mutex_exit(&cp->cache_lock);
1903 }
1904 
1905 /*
1906  * Return -1 if kmem_error, 1 if constructor fails, 0 if successful.
1907  */
1908 static int
1909 kmem_cache_alloc_debug(kmem_cache_t *cp, void *buf, int kmflag, int construct,
1910     caddr_t caller)
1911 {
1912 	kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1913 	kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
1914 	uint32_t mtbf;
1915 
1916 	if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
1917 		kmem_error(KMERR_BADBUFTAG, cp, buf);
1918 		return (-1);
1919 	}
1920 
1921 	btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_ALLOC;
1922 
1923 	if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
1924 		kmem_error(KMERR_BADBUFCTL, cp, buf);
1925 		return (-1);
1926 	}
1927 
1928 	if (cp->cache_flags & KMF_DEADBEEF) {
1929 		if (!construct && (cp->cache_flags & KMF_LITE)) {
1930 			if (*(uint64_t *)buf != KMEM_FREE_PATTERN) {
1931 				kmem_error(KMERR_MODIFIED, cp, buf);
1932 				return (-1);
1933 			}
1934 			if (cp->cache_constructor != NULL)
1935 				*(uint64_t *)buf = btp->bt_redzone;
1936 			else
1937 				*(uint64_t *)buf = KMEM_UNINITIALIZED_PATTERN;
1938 		} else {
1939 			construct = 1;
1940 			if (verify_and_copy_pattern(KMEM_FREE_PATTERN,
1941 			    KMEM_UNINITIALIZED_PATTERN, buf,
1942 			    cp->cache_verify)) {
1943 				kmem_error(KMERR_MODIFIED, cp, buf);
1944 				return (-1);
1945 			}
1946 		}
1947 	}
1948 	btp->bt_redzone = KMEM_REDZONE_PATTERN;
1949 
1950 	if ((mtbf = kmem_mtbf | cp->cache_mtbf) != 0 &&
1951 	    gethrtime() % mtbf == 0 &&
1952 	    (kmflag & (KM_NOSLEEP | KM_PANIC)) == KM_NOSLEEP) {
1953 		kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1954 		if (!construct && cp->cache_destructor != NULL)
1955 			cp->cache_destructor(buf, cp->cache_private);
1956 	} else {
1957 		mtbf = 0;
1958 	}
1959 
1960 	if (mtbf || (construct && cp->cache_constructor != NULL &&
1961 	    cp->cache_constructor(buf, cp->cache_private, kmflag) != 0)) {
1962 		atomic_inc_64(&cp->cache_alloc_fail);
1963 		btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1964 		if (cp->cache_flags & KMF_DEADBEEF)
1965 			copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1966 		kmem_slab_free(cp, buf);
1967 		return (1);
1968 	}
1969 
1970 	if (cp->cache_flags & KMF_AUDIT) {
1971 		KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1972 	}
1973 
1974 	if ((cp->cache_flags & KMF_LITE) &&
1975 	    !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
1976 		KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
1977 	}
1978 
1979 	return (0);
1980 }
1981 
1982 static int
1983 kmem_cache_free_debug(kmem_cache_t *cp, void *buf, caddr_t caller)
1984 {
1985 	kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1986 	kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
1987 	kmem_slab_t *sp;
1988 
1989 	if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_ALLOC)) {
1990 		if (btp->bt_bxstat == ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
1991 			kmem_error(KMERR_DUPFREE, cp, buf);
1992 			return (-1);
1993 		}
1994 		sp = kmem_findslab(cp, buf);
1995 		if (sp == NULL || sp->slab_cache != cp)
1996 			kmem_error(KMERR_BADADDR, cp, buf);
1997 		else
1998 			kmem_error(KMERR_REDZONE, cp, buf);
1999 		return (-1);
2000 	}
2001 
2002 	btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
2003 
2004 	if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
2005 		kmem_error(KMERR_BADBUFCTL, cp, buf);
2006 		return (-1);
2007 	}
2008 
2009 	if (btp->bt_redzone != KMEM_REDZONE_PATTERN) {
2010 		kmem_error(KMERR_REDZONE, cp, buf);
2011 		return (-1);
2012 	}
2013 
2014 	if (cp->cache_flags & KMF_AUDIT) {
2015 		if (cp->cache_flags & KMF_CONTENTS)
2016 			bcp->bc_contents = kmem_log_enter(kmem_content_log,
2017 			    buf, cp->cache_contents);
2018 		KMEM_AUDIT(kmem_transaction_log, cp, bcp);
2019 	}
2020 
2021 	if ((cp->cache_flags & KMF_LITE) &&
2022 	    !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
2023 		KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
2024 	}
2025 
2026 	if (cp->cache_flags & KMF_DEADBEEF) {
2027 		if (cp->cache_flags & KMF_LITE)
2028 			btp->bt_redzone = *(uint64_t *)buf;
2029 		else if (cp->cache_destructor != NULL)
2030 			cp->cache_destructor(buf, cp->cache_private);
2031 
2032 		copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
2033 	}
2034 
2035 	return (0);
2036 }
2037 
2038 /*
2039  * Free each object in magazine mp to cp's slab layer, and free mp itself.
2040  */
2041 static void
2042 kmem_magazine_destroy(kmem_cache_t *cp, kmem_magazine_t *mp, int nrounds)
2043 {
2044 	int round;
2045 
2046 	ASSERT(!list_link_active(&cp->cache_link) ||
2047 	    taskq_member(kmem_taskq, curthread));
2048 
2049 	for (round = 0; round < nrounds; round++) {
2050 		void *buf = mp->mag_round[round];
2051 
2052 		if (cp->cache_flags & KMF_DEADBEEF) {
2053 			if (verify_pattern(KMEM_FREE_PATTERN, buf,
2054 			    cp->cache_verify) != NULL) {
2055 				kmem_error(KMERR_MODIFIED, cp, buf);
2056 				continue;
2057 			}
2058 			if ((cp->cache_flags & KMF_LITE) &&
2059 			    cp->cache_destructor != NULL) {
2060 				kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2061 				*(uint64_t *)buf = btp->bt_redzone;
2062 				cp->cache_destructor(buf, cp->cache_private);
2063 				*(uint64_t *)buf = KMEM_FREE_PATTERN;
2064 			}
2065 		} else if (cp->cache_destructor != NULL) {
2066 			cp->cache_destructor(buf, cp->cache_private);
2067 		}
2068 
2069 		kmem_slab_free(cp, buf);
2070 	}
2071 	ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2072 	kmem_cache_free(cp->cache_magtype->mt_cache, mp);
2073 }
2074 
2075 /*
2076  * Allocate a magazine from the depot.
2077  */
2078 static kmem_magazine_t *
2079 kmem_depot_alloc(kmem_cache_t *cp, kmem_maglist_t *mlp)
2080 {
2081 	kmem_magazine_t *mp;
2082 
2083 	/*
2084 	 * If we can't get the depot lock without contention,
2085 	 * update our contention count.  We use the depot
2086 	 * contention rate to determine whether we need to
2087 	 * increase the magazine size for better scalability.
2088 	 */
2089 	if (!mutex_tryenter(&cp->cache_depot_lock)) {
2090 		mutex_enter(&cp->cache_depot_lock);
2091 		cp->cache_depot_contention++;
2092 	}
2093 
2094 	if ((mp = mlp->ml_list) != NULL) {
2095 		ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2096 		mlp->ml_list = mp->mag_next;
2097 		if (--mlp->ml_total < mlp->ml_min)
2098 			mlp->ml_min = mlp->ml_total;
2099 		mlp->ml_alloc++;
2100 	}
2101 
2102 	mutex_exit(&cp->cache_depot_lock);
2103 
2104 	return (mp);
2105 }
2106 
2107 /*
2108  * Free a magazine to the depot.
2109  */
2110 static void
2111 kmem_depot_free(kmem_cache_t *cp, kmem_maglist_t *mlp, kmem_magazine_t *mp)
2112 {
2113 	mutex_enter(&cp->cache_depot_lock);
2114 	ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2115 	mp->mag_next = mlp->ml_list;
2116 	mlp->ml_list = mp;
2117 	mlp->ml_total++;
2118 	mutex_exit(&cp->cache_depot_lock);
2119 }
2120 
2121 /*
2122  * Update the working set statistics for cp's depot.
2123  */
2124 static void
2125 kmem_depot_ws_update(kmem_cache_t *cp)
2126 {
2127 	mutex_enter(&cp->cache_depot_lock);
2128 	cp->cache_full.ml_reaplimit = cp->cache_full.ml_min;
2129 	cp->cache_full.ml_min = cp->cache_full.ml_total;
2130 	cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_min;
2131 	cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2132 	mutex_exit(&cp->cache_depot_lock);
2133 }
2134 
2135 /*
2136  * Set the working set statistics for cp's depot to zero.  (Everything is
2137  * eligible for reaping.)
2138  */
2139 static void
2140 kmem_depot_ws_zero(kmem_cache_t *cp)
2141 {
2142 	mutex_enter(&cp->cache_depot_lock);
2143 	cp->cache_full.ml_reaplimit = cp->cache_full.ml_total;
2144 	cp->cache_full.ml_min = cp->cache_full.ml_total;
2145 	cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_total;
2146 	cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2147 	mutex_exit(&cp->cache_depot_lock);
2148 }
2149 
2150 /*
2151  * The number of bytes to reap before we call kpreempt(). The default (1MB)
2152  * causes us to preempt reaping up to hundreds of times per second. Using a
2153  * larger value (1GB) causes this to have virtually no effect.
2154  */
2155 size_t kmem_reap_preempt_bytes = 1024 * 1024;
2156 
2157 /*
2158  * Reap all magazines that have fallen out of the depot's working set.
2159  */
2160 static void
2161 kmem_depot_ws_reap(kmem_cache_t *cp)
2162 {
2163 	size_t bytes = 0;
2164 	long reap;
2165 	kmem_magazine_t *mp;
2166 
2167 	ASSERT(!list_link_active(&cp->cache_link) ||
2168 	    taskq_member(kmem_taskq, curthread));
2169 
2170 	reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
2171 	while (reap-- &&
2172 	    (mp = kmem_depot_alloc(cp, &cp->cache_full)) != NULL) {
2173 		kmem_magazine_destroy(cp, mp, cp->cache_magtype->mt_magsize);
2174 		bytes += cp->cache_magtype->mt_magsize * cp->cache_bufsize;
2175 		if (bytes > kmem_reap_preempt_bytes) {
2176 			kpreempt(KPREEMPT_SYNC);
2177 			bytes = 0;
2178 		}
2179 	}
2180 
2181 	reap = MIN(cp->cache_empty.ml_reaplimit, cp->cache_empty.ml_min);
2182 	while (reap-- &&
2183 	    (mp = kmem_depot_alloc(cp, &cp->cache_empty)) != NULL) {
2184 		kmem_magazine_destroy(cp, mp, 0);
2185 		bytes += cp->cache_magtype->mt_magsize * cp->cache_bufsize;
2186 		if (bytes > kmem_reap_preempt_bytes) {
2187 			kpreempt(KPREEMPT_SYNC);
2188 			bytes = 0;
2189 		}
2190 	}
2191 }
2192 
2193 static void
2194 kmem_cpu_reload(kmem_cpu_cache_t *ccp, kmem_magazine_t *mp, int rounds)
2195 {
2196 	ASSERT((ccp->cc_loaded == NULL && ccp->cc_rounds == -1) ||
2197 	    (ccp->cc_loaded && ccp->cc_rounds + rounds == ccp->cc_magsize));
2198 	ASSERT(ccp->cc_magsize > 0);
2199 
2200 	ccp->cc_ploaded = ccp->cc_loaded;
2201 	ccp->cc_prounds = ccp->cc_rounds;
2202 	ccp->cc_loaded = mp;
2203 	ccp->cc_rounds = rounds;
2204 }
2205 
2206 /*
2207  * Intercept kmem alloc/free calls during crash dump in order to avoid
2208  * changing kmem state while memory is being saved to the dump device.
2209  * Otherwise, ::kmem_verify will report "corrupt buffers".  Note that
2210  * there are no locks because only one CPU calls kmem during a crash
2211  * dump. To enable this feature, first create the associated vmem
2212  * arena with VMC_DUMPSAFE.
2213  */
2214 static void *kmem_dump_start;	/* start of pre-reserved heap */
2215 static void *kmem_dump_end;	/* end of heap area */
2216 static void *kmem_dump_curr;	/* current free heap pointer */
2217 static size_t kmem_dump_size;	/* size of heap area */
2218 
2219 /* append to each buf created in the pre-reserved heap */
2220 typedef struct kmem_dumpctl {
2221 	void	*kdc_next;	/* cache dump free list linkage */
2222 } kmem_dumpctl_t;
2223 
2224 #define	KMEM_DUMPCTL(cp, buf)	\
2225 	((kmem_dumpctl_t *)P2ROUNDUP((uintptr_t)(buf) + (cp)->cache_bufsize, \
2226 	    sizeof (void *)))
2227 
2228 /* set non zero for full report */
2229 uint_t kmem_dump_verbose = 0;
2230 
2231 /* stats for overize heap */
2232 uint_t kmem_dump_oversize_allocs = 0;
2233 uint_t kmem_dump_oversize_max = 0;
2234 
2235 static void
2236 kmem_dumppr(char **pp, char *e, const char *format, ...)
2237 {
2238 	char *p = *pp;
2239 
2240 	if (p < e) {
2241 		int n;
2242 		va_list ap;
2243 
2244 		va_start(ap, format);
2245 		n = vsnprintf(p, e - p, format, ap);
2246 		va_end(ap);
2247 		*pp = p + n;
2248 	}
2249 }
2250 
2251 /*
2252  * Called when dumpadm(1M) configures dump parameters.
2253  */
2254 void
2255 kmem_dump_init(size_t size)
2256 {
2257 	/* Our caller ensures size is always set. */
2258 	ASSERT3U(size, >, 0);
2259 
2260 	if (kmem_dump_start != NULL)
2261 		kmem_free(kmem_dump_start, kmem_dump_size);
2262 
2263 	kmem_dump_start = kmem_alloc(size, KM_SLEEP);
2264 	kmem_dump_size = size;
2265 	kmem_dump_curr = kmem_dump_start;
2266 	kmem_dump_end = (void *)((char *)kmem_dump_start + size);
2267 	copy_pattern(KMEM_UNINITIALIZED_PATTERN, kmem_dump_start, size);
2268 }
2269 
2270 /*
2271  * Set flag for each kmem_cache_t if is safe to use alternate dump
2272  * memory. Called just before panic crash dump starts. Set the flag
2273  * for the calling CPU.
2274  */
2275 void
2276 kmem_dump_begin(void)
2277 {
2278 	kmem_cache_t *cp;
2279 
2280 	ASSERT(panicstr != NULL);
2281 
2282 	for (cp = list_head(&kmem_caches); cp != NULL;
2283 	    cp = list_next(&kmem_caches, cp)) {
2284 		kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2285 
2286 		if (cp->cache_arena->vm_cflags & VMC_DUMPSAFE) {
2287 			cp->cache_flags |= KMF_DUMPDIVERT;
2288 			ccp->cc_flags |= KMF_DUMPDIVERT;
2289 			ccp->cc_dump_rounds = ccp->cc_rounds;
2290 			ccp->cc_dump_prounds = ccp->cc_prounds;
2291 			ccp->cc_rounds = ccp->cc_prounds = -1;
2292 		} else {
2293 			cp->cache_flags |= KMF_DUMPUNSAFE;
2294 			ccp->cc_flags |= KMF_DUMPUNSAFE;
2295 		}
2296 	}
2297 }
2298 
2299 /*
2300  * finished dump intercept
2301  * print any warnings on the console
2302  * return verbose information to dumpsys() in the given buffer
2303  */
2304 size_t
2305 kmem_dump_finish(char *buf, size_t size)
2306 {
2307 	int percent = 0;
2308 	size_t used;
2309 	char *e = buf + size;
2310 	char *p = buf;
2311 
2312 	if (kmem_dump_curr == kmem_dump_end) {
2313 		cmn_err(CE_WARN, "exceeded kmem_dump space of %lu "
2314 		    "bytes: kmem state in dump may be inconsistent",
2315 		    kmem_dump_size);
2316 	}
2317 
2318 	if (kmem_dump_verbose == 0)
2319 		return (0);
2320 
2321 	used = (char *)kmem_dump_curr - (char *)kmem_dump_start;
2322 	percent = (used * 100) / kmem_dump_size;
2323 
2324 	kmem_dumppr(&p, e, "%% heap used,%d\n", percent);
2325 	kmem_dumppr(&p, e, "used bytes,%ld\n", used);
2326 	kmem_dumppr(&p, e, "heap size,%ld\n", kmem_dump_size);
2327 	kmem_dumppr(&p, e, "Oversize allocs,%d\n",
2328 	    kmem_dump_oversize_allocs);
2329 	kmem_dumppr(&p, e, "Oversize max size,%ld\n",
2330 	    kmem_dump_oversize_max);
2331 
2332 	/* return buffer size used */
2333 	if (p < e)
2334 		bzero(p, e - p);
2335 	return (p - buf);
2336 }
2337 
2338 /*
2339  * Allocate a constructed object from alternate dump memory.
2340  */
2341 void *
2342 kmem_cache_alloc_dump(kmem_cache_t *cp, int kmflag)
2343 {
2344 	void *buf;
2345 	void *curr;
2346 	char *bufend;
2347 
2348 	/* return a constructed object */
2349 	if ((buf = cp->cache_dump.kd_freelist) != NULL) {
2350 		cp->cache_dump.kd_freelist = KMEM_DUMPCTL(cp, buf)->kdc_next;
2351 		return (buf);
2352 	}
2353 
2354 	/* create a new constructed object */
2355 	curr = kmem_dump_curr;
2356 	buf = (void *)P2ROUNDUP((uintptr_t)curr, cp->cache_align);
2357 	bufend = (char *)KMEM_DUMPCTL(cp, buf) + sizeof (kmem_dumpctl_t);
2358 
2359 	/* hat layer objects cannot cross a page boundary */
2360 	if (cp->cache_align < PAGESIZE) {
2361 		char *page = (char *)P2ROUNDUP((uintptr_t)buf, PAGESIZE);
2362 		if (bufend > page) {
2363 			bufend += page - (char *)buf;
2364 			buf = (void *)page;
2365 		}
2366 	}
2367 
2368 	/* fall back to normal alloc if reserved area is used up */
2369 	if (bufend > (char *)kmem_dump_end) {
2370 		kmem_dump_curr = kmem_dump_end;
2371 		cp->cache_dump.kd_alloc_fails++;
2372 		return (NULL);
2373 	}
2374 
2375 	/*
2376 	 * Must advance curr pointer before calling a constructor that
2377 	 * may also allocate memory.
2378 	 */
2379 	kmem_dump_curr = bufend;
2380 
2381 	/* run constructor */
2382 	if (cp->cache_constructor != NULL &&
2383 	    cp->cache_constructor(buf, cp->cache_private, kmflag)
2384 	    != 0) {
2385 #ifdef DEBUG
2386 		printf("name='%s' cache=0x%p: kmem cache constructor failed\n",
2387 		    cp->cache_name, (void *)cp);
2388 #endif
2389 		/* reset curr pointer iff no allocs were done */
2390 		if (kmem_dump_curr == bufend)
2391 			kmem_dump_curr = curr;
2392 
2393 		cp->cache_dump.kd_alloc_fails++;
2394 		/* fall back to normal alloc if the constructor fails */
2395 		return (NULL);
2396 	}
2397 
2398 	return (buf);
2399 }
2400 
2401 /*
2402  * Free a constructed object in alternate dump memory.
2403  */
2404 int
2405 kmem_cache_free_dump(kmem_cache_t *cp, void *buf)
2406 {
2407 	/* save constructed buffers for next time */
2408 	if ((char *)buf >= (char *)kmem_dump_start &&
2409 	    (char *)buf < (char *)kmem_dump_end) {
2410 		KMEM_DUMPCTL(cp, buf)->kdc_next = cp->cache_dump.kd_freelist;
2411 		cp->cache_dump.kd_freelist = buf;
2412 		return (0);
2413 	}
2414 
2415 	/* just drop buffers that were allocated before dump started */
2416 	if (kmem_dump_curr < kmem_dump_end)
2417 		return (0);
2418 
2419 	/* fall back to normal free if reserved area is used up */
2420 	return (1);
2421 }
2422 
2423 /*
2424  * Allocate a constructed object from cache cp.
2425  */
2426 void *
2427 kmem_cache_alloc(kmem_cache_t *cp, int kmflag)
2428 {
2429 	kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2430 	kmem_magazine_t *fmp;
2431 	void *buf;
2432 
2433 	mutex_enter(&ccp->cc_lock);
2434 	for (;;) {
2435 		/*
2436 		 * If there's an object available in the current CPU's
2437 		 * loaded magazine, just take it and return.
2438 		 */
2439 		if (ccp->cc_rounds > 0) {
2440 			buf = ccp->cc_loaded->mag_round[--ccp->cc_rounds];
2441 			ccp->cc_alloc++;
2442 			mutex_exit(&ccp->cc_lock);
2443 			if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPUNSAFE)) {
2444 				if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2445 					ASSERT(!(ccp->cc_flags &
2446 					    KMF_DUMPDIVERT));
2447 					cp->cache_dump.kd_unsafe++;
2448 				}
2449 				if ((ccp->cc_flags & KMF_BUFTAG) &&
2450 				    kmem_cache_alloc_debug(cp, buf, kmflag, 0,
2451 				    caller()) != 0) {
2452 					if (kmflag & KM_NOSLEEP)
2453 						return (NULL);
2454 					mutex_enter(&ccp->cc_lock);
2455 					continue;
2456 				}
2457 			}
2458 			return (buf);
2459 		}
2460 
2461 		/*
2462 		 * The loaded magazine is empty.  If the previously loaded
2463 		 * magazine was full, exchange them and try again.
2464 		 */
2465 		if (ccp->cc_prounds > 0) {
2466 			kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2467 			continue;
2468 		}
2469 
2470 		/*
2471 		 * Return an alternate buffer at dump time to preserve
2472 		 * the heap.
2473 		 */
2474 		if (ccp->cc_flags & (KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2475 			if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2476 				ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2477 				/* log it so that we can warn about it */
2478 				cp->cache_dump.kd_unsafe++;
2479 			} else {
2480 				if ((buf = kmem_cache_alloc_dump(cp, kmflag)) !=
2481 				    NULL) {
2482 					mutex_exit(&ccp->cc_lock);
2483 					return (buf);
2484 				}
2485 				break;		/* fall back to slab layer */
2486 			}
2487 		}
2488 
2489 		/*
2490 		 * If the magazine layer is disabled, break out now.
2491 		 */
2492 		if (ccp->cc_magsize == 0)
2493 			break;
2494 
2495 		/*
2496 		 * Try to get a full magazine from the depot.
2497 		 */
2498 		fmp = kmem_depot_alloc(cp, &cp->cache_full);
2499 		if (fmp != NULL) {
2500 			if (ccp->cc_ploaded != NULL)
2501 				kmem_depot_free(cp, &cp->cache_empty,
2502 				    ccp->cc_ploaded);
2503 			kmem_cpu_reload(ccp, fmp, ccp->cc_magsize);
2504 			continue;
2505 		}
2506 
2507 		/*
2508 		 * There are no full magazines in the depot,
2509 		 * so fall through to the slab layer.
2510 		 */
2511 		break;
2512 	}
2513 	mutex_exit(&ccp->cc_lock);
2514 
2515 	/*
2516 	 * We couldn't allocate a constructed object from the magazine layer,
2517 	 * so get a raw buffer from the slab layer and apply its constructor.
2518 	 */
2519 	buf = kmem_slab_alloc(cp, kmflag);
2520 
2521 	if (buf == NULL)
2522 		return (NULL);
2523 
2524 	if (cp->cache_flags & KMF_BUFTAG) {
2525 		/*
2526 		 * Make kmem_cache_alloc_debug() apply the constructor for us.
2527 		 */
2528 		int rc = kmem_cache_alloc_debug(cp, buf, kmflag, 1, caller());
2529 		if (rc != 0) {
2530 			if (kmflag & KM_NOSLEEP)
2531 				return (NULL);
2532 			/*
2533 			 * kmem_cache_alloc_debug() detected corruption
2534 			 * but didn't panic (kmem_panic <= 0). We should not be
2535 			 * here because the constructor failed (indicated by a
2536 			 * return code of 1). Try again.
2537 			 */
2538 			ASSERT(rc == -1);
2539 			return (kmem_cache_alloc(cp, kmflag));
2540 		}
2541 		return (buf);
2542 	}
2543 
2544 	if (cp->cache_constructor != NULL &&
2545 	    cp->cache_constructor(buf, cp->cache_private, kmflag) != 0) {
2546 		atomic_inc_64(&cp->cache_alloc_fail);
2547 		kmem_slab_free(cp, buf);
2548 		return (NULL);
2549 	}
2550 
2551 	return (buf);
2552 }
2553 
2554 /*
2555  * The freed argument tells whether or not kmem_cache_free_debug() has already
2556  * been called so that we can avoid the duplicate free error. For example, a
2557  * buffer on a magazine has already been freed by the client but is still
2558  * constructed.
2559  */
2560 static void
2561 kmem_slab_free_constructed(kmem_cache_t *cp, void *buf, boolean_t freed)
2562 {
2563 	if (!freed && (cp->cache_flags & KMF_BUFTAG))
2564 		if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2565 			return;
2566 
2567 	/*
2568 	 * Note that if KMF_DEADBEEF is in effect and KMF_LITE is not,
2569 	 * kmem_cache_free_debug() will have already applied the destructor.
2570 	 */
2571 	if ((cp->cache_flags & (KMF_DEADBEEF | KMF_LITE)) != KMF_DEADBEEF &&
2572 	    cp->cache_destructor != NULL) {
2573 		if (cp->cache_flags & KMF_DEADBEEF) {	/* KMF_LITE implied */
2574 			kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2575 			*(uint64_t *)buf = btp->bt_redzone;
2576 			cp->cache_destructor(buf, cp->cache_private);
2577 			*(uint64_t *)buf = KMEM_FREE_PATTERN;
2578 		} else {
2579 			cp->cache_destructor(buf, cp->cache_private);
2580 		}
2581 	}
2582 
2583 	kmem_slab_free(cp, buf);
2584 }
2585 
2586 /*
2587  * Used when there's no room to free a buffer to the per-CPU cache.
2588  * Drops and re-acquires &ccp->cc_lock, and returns non-zero if the
2589  * caller should try freeing to the per-CPU cache again.
2590  * Note that we don't directly install the magazine in the cpu cache,
2591  * since its state may have changed wildly while the lock was dropped.
2592  */
2593 static int
2594 kmem_cpucache_magazine_alloc(kmem_cpu_cache_t *ccp, kmem_cache_t *cp)
2595 {
2596 	kmem_magazine_t *emp;
2597 	kmem_magtype_t *mtp;
2598 
2599 	ASSERT(MUTEX_HELD(&ccp->cc_lock));
2600 	ASSERT(((uint_t)ccp->cc_rounds == ccp->cc_magsize ||
2601 	    ((uint_t)ccp->cc_rounds == -1)) &&
2602 	    ((uint_t)ccp->cc_prounds == ccp->cc_magsize ||
2603 	    ((uint_t)ccp->cc_prounds == -1)));
2604 
2605 	emp = kmem_depot_alloc(cp, &cp->cache_empty);
2606 	if (emp != NULL) {
2607 		if (ccp->cc_ploaded != NULL)
2608 			kmem_depot_free(cp, &cp->cache_full,
2609 			    ccp->cc_ploaded);
2610 		kmem_cpu_reload(ccp, emp, 0);
2611 		return (1);
2612 	}
2613 	/*
2614 	 * There are no empty magazines in the depot,
2615 	 * so try to allocate a new one.  We must drop all locks
2616 	 * across kmem_cache_alloc() because lower layers may
2617 	 * attempt to allocate from this cache.
2618 	 */
2619 	mtp = cp->cache_magtype;
2620 	mutex_exit(&ccp->cc_lock);
2621 	emp = kmem_cache_alloc(mtp->mt_cache, KM_NOSLEEP);
2622 	mutex_enter(&ccp->cc_lock);
2623 
2624 	if (emp != NULL) {
2625 		/*
2626 		 * We successfully allocated an empty magazine.
2627 		 * However, we had to drop ccp->cc_lock to do it,
2628 		 * so the cache's magazine size may have changed.
2629 		 * If so, free the magazine and try again.
2630 		 */
2631 		if (ccp->cc_magsize != mtp->mt_magsize) {
2632 			mutex_exit(&ccp->cc_lock);
2633 			kmem_cache_free(mtp->mt_cache, emp);
2634 			mutex_enter(&ccp->cc_lock);
2635 			return (1);
2636 		}
2637 
2638 		/*
2639 		 * We got a magazine of the right size.  Add it to
2640 		 * the depot and try the whole dance again.
2641 		 */
2642 		kmem_depot_free(cp, &cp->cache_empty, emp);
2643 		return (1);
2644 	}
2645 
2646 	/*
2647 	 * We couldn't allocate an empty magazine,
2648 	 * so fall through to the slab layer.
2649 	 */
2650 	return (0);
2651 }
2652 
2653 /*
2654  * Free a constructed object to cache cp.
2655  */
2656 void
2657 kmem_cache_free(kmem_cache_t *cp, void *buf)
2658 {
2659 	kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2660 
2661 	/*
2662 	 * The client must not free either of the buffers passed to the move
2663 	 * callback function.
2664 	 */
2665 	ASSERT(cp->cache_defrag == NULL ||
2666 	    cp->cache_defrag->kmd_thread != curthread ||
2667 	    (buf != cp->cache_defrag->kmd_from_buf &&
2668 	    buf != cp->cache_defrag->kmd_to_buf));
2669 
2670 	if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2671 		if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2672 			ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2673 			/* log it so that we can warn about it */
2674 			cp->cache_dump.kd_unsafe++;
2675 		} else if (KMEM_DUMPCC(ccp) && !kmem_cache_free_dump(cp, buf)) {
2676 			return;
2677 		}
2678 		if (ccp->cc_flags & KMF_BUFTAG) {
2679 			if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2680 				return;
2681 		}
2682 	}
2683 
2684 	mutex_enter(&ccp->cc_lock);
2685 	/*
2686 	 * Any changes to this logic should be reflected in kmem_slab_prefill()
2687 	 */
2688 	for (;;) {
2689 		/*
2690 		 * If there's a slot available in the current CPU's
2691 		 * loaded magazine, just put the object there and return.
2692 		 */
2693 		if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2694 			ccp->cc_loaded->mag_round[ccp->cc_rounds++] = buf;
2695 			ccp->cc_free++;
2696 			mutex_exit(&ccp->cc_lock);
2697 			return;
2698 		}
2699 
2700 		/*
2701 		 * The loaded magazine is full.  If the previously loaded
2702 		 * magazine was empty, exchange them and try again.
2703 		 */
2704 		if (ccp->cc_prounds == 0) {
2705 			kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2706 			continue;
2707 		}
2708 
2709 		/*
2710 		 * If the magazine layer is disabled, break out now.
2711 		 */
2712 		if (ccp->cc_magsize == 0)
2713 			break;
2714 
2715 		if (!kmem_cpucache_magazine_alloc(ccp, cp)) {
2716 			/*
2717 			 * We couldn't free our constructed object to the
2718 			 * magazine layer, so apply its destructor and free it
2719 			 * to the slab layer.
2720 			 */
2721 			break;
2722 		}
2723 	}
2724 	mutex_exit(&ccp->cc_lock);
2725 	kmem_slab_free_constructed(cp, buf, B_TRUE);
2726 }
2727 
2728 static void
2729 kmem_slab_prefill(kmem_cache_t *cp, kmem_slab_t *sp)
2730 {
2731 	kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2732 	int cache_flags = cp->cache_flags;
2733 
2734 	kmem_bufctl_t *next, *head;
2735 	size_t nbufs;
2736 
2737 	/*
2738 	 * Completely allocate the newly created slab and put the pre-allocated
2739 	 * buffers in magazines. Any of the buffers that cannot be put in
2740 	 * magazines must be returned to the slab.
2741 	 */
2742 	ASSERT(MUTEX_HELD(&cp->cache_lock));
2743 	ASSERT((cache_flags & (KMF_PREFILL|KMF_BUFTAG)) == KMF_PREFILL);
2744 	ASSERT(cp->cache_constructor == NULL);
2745 	ASSERT(sp->slab_cache == cp);
2746 	ASSERT(sp->slab_refcnt == 1);
2747 	ASSERT(sp->slab_head != NULL && sp->slab_chunks > sp->slab_refcnt);
2748 	ASSERT(avl_find(&cp->cache_partial_slabs, sp, NULL) == NULL);
2749 
2750 	head = sp->slab_head;
2751 	nbufs = (sp->slab_chunks - sp->slab_refcnt);
2752 	sp->slab_head = NULL;
2753 	sp->slab_refcnt += nbufs;
2754 	cp->cache_bufslab -= nbufs;
2755 	cp->cache_slab_alloc += nbufs;
2756 	list_insert_head(&cp->cache_complete_slabs, sp);
2757 	cp->cache_complete_slab_count++;
2758 	mutex_exit(&cp->cache_lock);
2759 	mutex_enter(&ccp->cc_lock);
2760 
2761 	while (head != NULL) {
2762 		void *buf = KMEM_BUF(cp, head);
2763 		/*
2764 		 * If there's a slot available in the current CPU's
2765 		 * loaded magazine, just put the object there and
2766 		 * continue.
2767 		 */
2768 		if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2769 			ccp->cc_loaded->mag_round[ccp->cc_rounds++] =
2770 			    buf;
2771 			ccp->cc_free++;
2772 			nbufs--;
2773 			head = head->bc_next;
2774 			continue;
2775 		}
2776 
2777 		/*
2778 		 * The loaded magazine is full.  If the previously
2779 		 * loaded magazine was empty, exchange them and try
2780 		 * again.
2781 		 */
2782 		if (ccp->cc_prounds == 0) {
2783 			kmem_cpu_reload(ccp, ccp->cc_ploaded,
2784 			    ccp->cc_prounds);
2785 			continue;
2786 		}
2787 
2788 		/*
2789 		 * If the magazine layer is disabled, break out now.
2790 		 */
2791 
2792 		if (ccp->cc_magsize == 0) {
2793 			break;
2794 		}
2795 
2796 		if (!kmem_cpucache_magazine_alloc(ccp, cp))
2797 			break;
2798 	}
2799 	mutex_exit(&ccp->cc_lock);
2800 	if (nbufs != 0) {
2801 		ASSERT(head != NULL);
2802 
2803 		/*
2804 		 * If there was a failure, return remaining objects to
2805 		 * the slab
2806 		 */
2807 		while (head != NULL) {
2808 			ASSERT(nbufs != 0);
2809 			next = head->bc_next;
2810 			head->bc_next = NULL;
2811 			kmem_slab_free(cp, KMEM_BUF(cp, head));
2812 			head = next;
2813 			nbufs--;
2814 		}
2815 	}
2816 	ASSERT(head == NULL);
2817 	ASSERT(nbufs == 0);
2818 	mutex_enter(&cp->cache_lock);
2819 }
2820 
2821 void *
2822 kmem_zalloc(size_t size, int kmflag)
2823 {
2824 	size_t index;
2825 	void *buf;
2826 
2827 	if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2828 		kmem_cache_t *cp = kmem_alloc_table[index];
2829 		buf = kmem_cache_alloc(cp, kmflag);
2830 		if (buf != NULL) {
2831 			if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2832 				kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2833 				((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2834 				((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2835 
2836 				if (cp->cache_flags & KMF_LITE) {
2837 					KMEM_BUFTAG_LITE_ENTER(btp,
2838 					    kmem_lite_count, caller());
2839 				}
2840 			}
2841 			bzero(buf, size);
2842 		}
2843 	} else {
2844 		buf = kmem_alloc(size, kmflag);
2845 		if (buf != NULL)
2846 			bzero(buf, size);
2847 	}
2848 	return (buf);
2849 }
2850 
2851 void *
2852 kmem_alloc(size_t size, int kmflag)
2853 {
2854 	size_t index;
2855 	kmem_cache_t *cp;
2856 	void *buf;
2857 
2858 	if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2859 		cp = kmem_alloc_table[index];
2860 		/* fall through to kmem_cache_alloc() */
2861 
2862 	} else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2863 	    kmem_big_alloc_table_max) {
2864 		cp = kmem_big_alloc_table[index];
2865 		/* fall through to kmem_cache_alloc() */
2866 
2867 	} else {
2868 		if (size == 0) {
2869 			if (kmflag != KM_SLEEP && !(kmflag & KM_PANIC))
2870 				return (NULL);
2871 
2872 			/*
2873 			 * If this is a sleeping allocation or one that has
2874 			 * been specified to panic on allocation failure, we
2875 			 * consider it to be deprecated behavior to allocate
2876 			 * 0 bytes.  If we have been configured to panic under
2877 			 * this condition, we panic; if to warn, we warn -- and
2878 			 * regardless, we log to the kmem_zerosized_log that
2879 			 * that this condition has occurred (which gives us
2880 			 * enough information to be able to debug it).
2881 			 */
2882 			if (kmem_panic && kmem_panic_zerosized)
2883 				panic("attempted to kmem_alloc() size of 0");
2884 
2885 			if (kmem_warn_zerosized) {
2886 				cmn_err(CE_WARN, "kmem_alloc(): sleeping "
2887 				    "allocation with size of 0; "
2888 				    "see kmem_zerosized_log for details");
2889 			}
2890 
2891 			kmem_log_event(kmem_zerosized_log, NULL, NULL, NULL);
2892 
2893 			return (NULL);
2894 		}
2895 
2896 		buf = vmem_alloc(kmem_oversize_arena, size,
2897 		    kmflag & KM_VMFLAGS);
2898 		if (buf == NULL)
2899 			kmem_log_event(kmem_failure_log, NULL, NULL,
2900 			    (void *)size);
2901 		else if (KMEM_DUMP(kmem_slab_cache)) {
2902 			/* stats for dump intercept */
2903 			kmem_dump_oversize_allocs++;
2904 			if (size > kmem_dump_oversize_max)
2905 				kmem_dump_oversize_max = size;
2906 		}
2907 		return (buf);
2908 	}
2909 
2910 	buf = kmem_cache_alloc(cp, kmflag);
2911 	if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp) && buf != NULL) {
2912 		kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2913 		((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2914 		((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2915 
2916 		if (cp->cache_flags & KMF_LITE) {
2917 			KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller());
2918 		}
2919 	}
2920 	return (buf);
2921 }
2922 
2923 void
2924 kmem_free(void *buf, size_t size)
2925 {
2926 	size_t index;
2927 	kmem_cache_t *cp;
2928 
2929 	if ((index = (size - 1) >> KMEM_ALIGN_SHIFT) < KMEM_ALLOC_TABLE_MAX) {
2930 		cp = kmem_alloc_table[index];
2931 		/* fall through to kmem_cache_free() */
2932 
2933 	} else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2934 	    kmem_big_alloc_table_max) {
2935 		cp = kmem_big_alloc_table[index];
2936 		/* fall through to kmem_cache_free() */
2937 
2938 	} else {
2939 		EQUIV(buf == NULL, size == 0);
2940 		if (buf == NULL && size == 0)
2941 			return;
2942 		vmem_free(kmem_oversize_arena, buf, size);
2943 		return;
2944 	}
2945 
2946 	if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2947 		kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2948 		uint32_t *ip = (uint32_t *)btp;
2949 		if (ip[1] != KMEM_SIZE_ENCODE(size)) {
2950 			if (*(uint64_t *)buf == KMEM_FREE_PATTERN) {
2951 				kmem_error(KMERR_DUPFREE, cp, buf);
2952 				return;
2953 			}
2954 			if (KMEM_SIZE_VALID(ip[1])) {
2955 				ip[0] = KMEM_SIZE_ENCODE(size);
2956 				kmem_error(KMERR_BADSIZE, cp, buf);
2957 			} else {
2958 				kmem_error(KMERR_REDZONE, cp, buf);
2959 			}
2960 			return;
2961 		}
2962 		if (((uint8_t *)buf)[size] != KMEM_REDZONE_BYTE) {
2963 			kmem_error(KMERR_REDZONE, cp, buf);
2964 			return;
2965 		}
2966 		btp->bt_redzone = KMEM_REDZONE_PATTERN;
2967 		if (cp->cache_flags & KMF_LITE) {
2968 			KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count,
2969 			    caller());
2970 		}
2971 	}
2972 	kmem_cache_free(cp, buf);
2973 }
2974 
2975 void *
2976 kmem_firewall_va_alloc(vmem_t *vmp, size_t size, int vmflag)
2977 {
2978 	size_t realsize = size + vmp->vm_quantum;
2979 	void *addr;
2980 
2981 	/*
2982 	 * Annoying edge case: if 'size' is just shy of ULONG_MAX, adding
2983 	 * vm_quantum will cause integer wraparound.  Check for this, and
2984 	 * blow off the firewall page in this case.  Note that such a
2985 	 * giant allocation (the entire kernel address space) can never
2986 	 * be satisfied, so it will either fail immediately (VM_NOSLEEP)
2987 	 * or sleep forever (VM_SLEEP).  Thus, there is no need for a
2988 	 * corresponding check in kmem_firewall_va_free().
2989 	 */
2990 	if (realsize < size)
2991 		realsize = size;
2992 
2993 	/*
2994 	 * While boot still owns resource management, make sure that this
2995 	 * redzone virtual address allocation is properly accounted for in
2996 	 * OBPs "virtual-memory" "available" lists because we're
2997 	 * effectively claiming them for a red zone.  If we don't do this,
2998 	 * the available lists become too fragmented and too large for the
2999 	 * current boot/kernel memory list interface.
3000 	 */
3001 	addr = vmem_alloc(vmp, realsize, vmflag | VM_NEXTFIT);
3002 
3003 	if (addr != NULL && kvseg.s_base == NULL && realsize != size)
3004 		(void) boot_virt_alloc((char *)addr + size, vmp->vm_quantum);
3005 
3006 	return (addr);
3007 }
3008 
3009 void
3010 kmem_firewall_va_free(vmem_t *vmp, void *addr, size_t size)
3011 {
3012 	ASSERT((kvseg.s_base == NULL ?
3013 	    va_to_pfn((char *)addr + size) :
3014 	    hat_getpfnum(kas.a_hat, (caddr_t)addr + size)) == PFN_INVALID);
3015 
3016 	vmem_free(vmp, addr, size + vmp->vm_quantum);
3017 }
3018 
3019 /*
3020  * Try to allocate at least `size' bytes of memory without sleeping or
3021  * panicking. Return actual allocated size in `asize'. If allocation failed,
3022  * try final allocation with sleep or panic allowed.
3023  */
3024 void *
3025 kmem_alloc_tryhard(size_t size, size_t *asize, int kmflag)
3026 {
3027 	void *p;
3028 
3029 	*asize = P2ROUNDUP(size, KMEM_ALIGN);
3030 	do {
3031 		p = kmem_alloc(*asize, (kmflag | KM_NOSLEEP) & ~KM_PANIC);
3032 		if (p != NULL)
3033 			return (p);
3034 		*asize += KMEM_ALIGN;
3035 	} while (*asize <= PAGESIZE);
3036 
3037 	*asize = P2ROUNDUP(size, KMEM_ALIGN);
3038 	return (kmem_alloc(*asize, kmflag));
3039 }
3040 
3041 /*
3042  * Reclaim all unused memory from a cache.
3043  */
3044 static void
3045 kmem_cache_reap(kmem_cache_t *cp)
3046 {
3047 	ASSERT(taskq_member(kmem_taskq, curthread));
3048 	cp->cache_reap++;
3049 
3050 	/*
3051 	 * Ask the cache's owner to free some memory if possible.
3052 	 * The idea is to handle things like the inode cache, which
3053 	 * typically sits on a bunch of memory that it doesn't truly
3054 	 * *need*.  Reclaim policy is entirely up to the owner; this
3055 	 * callback is just an advisory plea for help.
3056 	 */
3057 	if (cp->cache_reclaim != NULL) {
3058 		long delta;
3059 
3060 		/*
3061 		 * Reclaimed memory should be reapable (not included in the
3062 		 * depot's working set).
3063 		 */
3064 		delta = cp->cache_full.ml_total;
3065 		cp->cache_reclaim(cp->cache_private);
3066 		delta = cp->cache_full.ml_total - delta;
3067 		if (delta > 0) {
3068 			mutex_enter(&cp->cache_depot_lock);
3069 			cp->cache_full.ml_reaplimit += delta;
3070 			cp->cache_full.ml_min += delta;
3071 			mutex_exit(&cp->cache_depot_lock);
3072 		}
3073 	}
3074 
3075 	kmem_depot_ws_reap(cp);
3076 
3077 	if (cp->cache_defrag != NULL && !kmem_move_noreap) {
3078 		kmem_cache_defrag(cp);
3079 	}
3080 }
3081 
3082 static void
3083 kmem_reap_timeout(void *flag_arg)
3084 {
3085 	uint32_t *flag = (uint32_t *)flag_arg;
3086 
3087 	ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3088 	*flag = 0;
3089 }
3090 
3091 static void
3092 kmem_reap_done(void *flag)
3093 {
3094 	if (!callout_init_done) {
3095 		/* can't schedule a timeout at this point */
3096 		kmem_reap_timeout(flag);
3097 	} else {
3098 		(void) timeout(kmem_reap_timeout, flag, kmem_reap_interval);
3099 	}
3100 }
3101 
3102 static void
3103 kmem_reap_start(void *flag)
3104 {
3105 	ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3106 
3107 	if (flag == &kmem_reaping) {
3108 		kmem_cache_applyall(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3109 		/*
3110 		 * if we have segkp under heap, reap segkp cache.
3111 		 */
3112 		if (segkp_fromheap)
3113 			segkp_cache_free();
3114 	}
3115 	else
3116 		kmem_cache_applyall_id(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3117 
3118 	/*
3119 	 * We use taskq_dispatch() to schedule a timeout to clear
3120 	 * the flag so that kmem_reap() becomes self-throttling:
3121 	 * we won't reap again until the current reap completes *and*
3122 	 * at least kmem_reap_interval ticks have elapsed.
3123 	 */
3124 	if (taskq_dispatch(kmem_taskq, kmem_reap_done, flag, TQ_NOSLEEP) ==
3125 	    TASKQID_INVALID)
3126 		kmem_reap_done(flag);
3127 }
3128 
3129 static void
3130 kmem_reap_common(void *flag_arg)
3131 {
3132 	uint32_t *flag = (uint32_t *)flag_arg;
3133 
3134 	if (MUTEX_HELD(&kmem_cache_lock) || kmem_taskq == NULL ||
3135 	    atomic_cas_32(flag, 0, 1) != 0)
3136 		return;
3137 
3138 	/*
3139 	 * It may not be kosher to do memory allocation when a reap is called
3140 	 * (for example, if vmem_populate() is in the call chain).  So we
3141 	 * start the reap going with a TQ_NOALLOC dispatch.  If the dispatch
3142 	 * fails, we reset the flag, and the next reap will try again.
3143 	 */
3144 	if (taskq_dispatch(kmem_taskq, kmem_reap_start, flag, TQ_NOALLOC) ==
3145 	    TASKQID_INVALID)
3146 		*flag = 0;
3147 }
3148 
3149 /*
3150  * Reclaim all unused memory from all caches.  Called from the VM system
3151  * when memory gets tight.
3152  */
3153 void
3154 kmem_reap(void)
3155 {
3156 	kmem_reap_common(&kmem_reaping);
3157 }
3158 
3159 /*
3160  * Reclaim all unused memory from identifier arenas, called when a vmem
3161  * arena not back by memory is exhausted.  Since reaping memory-backed caches
3162  * cannot help with identifier exhaustion, we avoid both a large amount of
3163  * work and unwanted side-effects from reclaim callbacks.
3164  */
3165 void
3166 kmem_reap_idspace(void)
3167 {
3168 	kmem_reap_common(&kmem_reaping_idspace);
3169 }
3170 
3171 /*
3172  * Purge all magazines from a cache and set its magazine limit to zero.
3173  * All calls are serialized by the kmem_taskq lock, except for the final
3174  * call from kmem_cache_destroy().
3175  */
3176 static void
3177 kmem_cache_magazine_purge(kmem_cache_t *cp)
3178 {
3179 	kmem_cpu_cache_t *ccp;
3180 	kmem_magazine_t *mp, *pmp;
3181 	int rounds, prounds, cpu_seqid;
3182 
3183 	ASSERT(!list_link_active(&cp->cache_link) ||
3184 	    taskq_member(kmem_taskq, curthread));
3185 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
3186 
3187 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3188 		ccp = &cp->cache_cpu[cpu_seqid];
3189 
3190 		mutex_enter(&ccp->cc_lock);
3191 		mp = ccp->cc_loaded;
3192 		pmp = ccp->cc_ploaded;
3193 		rounds = ccp->cc_rounds;
3194 		prounds = ccp->cc_prounds;
3195 		ccp->cc_loaded = NULL;
3196 		ccp->cc_ploaded = NULL;
3197 		ccp->cc_rounds = -1;
3198 		ccp->cc_prounds = -1;
3199 		ccp->cc_magsize = 0;
3200 		mutex_exit(&ccp->cc_lock);
3201 
3202 		if (mp)
3203 			kmem_magazine_destroy(cp, mp, rounds);
3204 		if (pmp)
3205 			kmem_magazine_destroy(cp, pmp, prounds);
3206 	}
3207 
3208 	kmem_depot_ws_zero(cp);
3209 	kmem_depot_ws_reap(cp);
3210 }
3211 
3212 /*
3213  * Enable per-cpu magazines on a cache.
3214  */
3215 static void
3216 kmem_cache_magazine_enable(kmem_cache_t *cp)
3217 {
3218 	int cpu_seqid;
3219 
3220 	if (cp->cache_flags & KMF_NOMAGAZINE)
3221 		return;
3222 
3223 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3224 		kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3225 		mutex_enter(&ccp->cc_lock);
3226 		ccp->cc_magsize = cp->cache_magtype->mt_magsize;
3227 		mutex_exit(&ccp->cc_lock);
3228 	}
3229 
3230 }
3231 
3232 /*
3233  * Allow our caller to determine if there are running reaps.
3234  *
3235  * This call is very conservative and may return B_TRUE even when
3236  * reaping activity isn't active. If it returns B_FALSE, then reaping
3237  * activity is definitely inactive.
3238  */
3239 boolean_t
3240 kmem_cache_reap_active(void)
3241 {
3242 	return (!taskq_empty(kmem_taskq));
3243 }
3244 
3245 /*
3246  * Reap (almost) everything soon.
3247  *
3248  * Note: this does not wait for the reap-tasks to complete. Caller
3249  * should use kmem_cache_reap_active() (above) and/or moderation to
3250  * avoid scheduling too many reap-tasks.
3251  */
3252 void
3253 kmem_cache_reap_soon(kmem_cache_t *cp)
3254 {
3255 	ASSERT(list_link_active(&cp->cache_link));
3256 
3257 	kmem_depot_ws_zero(cp);
3258 
3259 	(void) taskq_dispatch(kmem_taskq,
3260 	    (task_func_t *)kmem_depot_ws_reap, cp, TQ_SLEEP);
3261 }
3262 
3263 /*
3264  * Recompute a cache's magazine size.  The trade-off is that larger magazines
3265  * provide a higher transfer rate with the depot, while smaller magazines
3266  * reduce memory consumption.  Magazine resizing is an expensive operation;
3267  * it should not be done frequently.
3268  *
3269  * Changes to the magazine size are serialized by the kmem_taskq lock.
3270  *
3271  * Note: at present this only grows the magazine size.  It might be useful
3272  * to allow shrinkage too.
3273  */
3274 static void
3275 kmem_cache_magazine_resize(kmem_cache_t *cp)
3276 {
3277 	kmem_magtype_t *mtp = cp->cache_magtype;
3278 
3279 	ASSERT(taskq_member(kmem_taskq, curthread));
3280 
3281 	if (cp->cache_chunksize < mtp->mt_maxbuf) {
3282 		kmem_cache_magazine_purge(cp);
3283 		mutex_enter(&cp->cache_depot_lock);
3284 		cp->cache_magtype = ++mtp;
3285 		cp->cache_depot_contention_prev =
3286 		    cp->cache_depot_contention + INT_MAX;
3287 		mutex_exit(&cp->cache_depot_lock);
3288 		kmem_cache_magazine_enable(cp);
3289 	}
3290 }
3291 
3292 /*
3293  * Rescale a cache's hash table, so that the table size is roughly the
3294  * cache size.  We want the average lookup time to be extremely small.
3295  */
3296 static void
3297 kmem_hash_rescale(kmem_cache_t *cp)
3298 {
3299 	kmem_bufctl_t **old_table, **new_table, *bcp;
3300 	size_t old_size, new_size, h;
3301 
3302 	ASSERT(taskq_member(kmem_taskq, curthread));
3303 
3304 	new_size = MAX(KMEM_HASH_INITIAL,
3305 	    1 << (highbit(3 * cp->cache_buftotal + 4) - 2));
3306 	old_size = cp->cache_hash_mask + 1;
3307 
3308 	if ((old_size >> 1) <= new_size && new_size <= (old_size << 1))
3309 		return;
3310 
3311 	new_table = vmem_alloc(kmem_hash_arena, new_size * sizeof (void *),
3312 	    VM_NOSLEEP);
3313 	if (new_table == NULL)
3314 		return;
3315 	bzero(new_table, new_size * sizeof (void *));
3316 
3317 	mutex_enter(&cp->cache_lock);
3318 
3319 	old_size = cp->cache_hash_mask + 1;
3320 	old_table = cp->cache_hash_table;
3321 
3322 	cp->cache_hash_mask = new_size - 1;
3323 	cp->cache_hash_table = new_table;
3324 	cp->cache_rescale++;
3325 
3326 	for (h = 0; h < old_size; h++) {
3327 		bcp = old_table[h];
3328 		while (bcp != NULL) {
3329 			void *addr = bcp->bc_addr;
3330 			kmem_bufctl_t *next_bcp = bcp->bc_next;
3331 			kmem_bufctl_t **hash_bucket = KMEM_HASH(cp, addr);
3332 			bcp->bc_next = *hash_bucket;
3333 			*hash_bucket = bcp;
3334 			bcp = next_bcp;
3335 		}
3336 	}
3337 
3338 	mutex_exit(&cp->cache_lock);
3339 
3340 	vmem_free(kmem_hash_arena, old_table, old_size * sizeof (void *));
3341 }
3342 
3343 /*
3344  * Perform periodic maintenance on a cache: hash rescaling, depot working-set
3345  * update, magazine resizing, and slab consolidation.
3346  */
3347 static void
3348 kmem_cache_update(kmem_cache_t *cp)
3349 {
3350 	int need_hash_rescale = 0;
3351 	int need_magazine_resize = 0;
3352 
3353 	ASSERT(MUTEX_HELD(&kmem_cache_lock));
3354 
3355 	/*
3356 	 * If the cache has become much larger or smaller than its hash table,
3357 	 * fire off a request to rescale the hash table.
3358 	 */
3359 	mutex_enter(&cp->cache_lock);
3360 
3361 	if ((cp->cache_flags & KMF_HASH) &&
3362 	    (cp->cache_buftotal > (cp->cache_hash_mask << 1) ||
3363 	    (cp->cache_buftotal < (cp->cache_hash_mask >> 1) &&
3364 	    cp->cache_hash_mask > KMEM_HASH_INITIAL)))
3365 		need_hash_rescale = 1;
3366 
3367 	mutex_exit(&cp->cache_lock);
3368 
3369 	/*
3370 	 * Update the depot working set statistics.
3371 	 */
3372 	kmem_depot_ws_update(cp);
3373 
3374 	/*
3375 	 * If there's a lot of contention in the depot,
3376 	 * increase the magazine size.
3377 	 */
3378 	mutex_enter(&cp->cache_depot_lock);
3379 
3380 	if (cp->cache_chunksize < cp->cache_magtype->mt_maxbuf &&
3381 	    (int)(cp->cache_depot_contention -
3382 	    cp->cache_depot_contention_prev) > kmem_depot_contention)
3383 		need_magazine_resize = 1;
3384 
3385 	cp->cache_depot_contention_prev = cp->cache_depot_contention;
3386 
3387 	mutex_exit(&cp->cache_depot_lock);
3388 
3389 	if (need_hash_rescale)
3390 		(void) taskq_dispatch(kmem_taskq,
3391 		    (task_func_t *)kmem_hash_rescale, cp, TQ_NOSLEEP);
3392 
3393 	if (need_magazine_resize)
3394 		(void) taskq_dispatch(kmem_taskq,
3395 		    (task_func_t *)kmem_cache_magazine_resize, cp, TQ_NOSLEEP);
3396 
3397 	if (cp->cache_defrag != NULL)
3398 		(void) taskq_dispatch(kmem_taskq,
3399 		    (task_func_t *)kmem_cache_scan, cp, TQ_NOSLEEP);
3400 }
3401 
3402 static void kmem_update(void *);
3403 
3404 static void
3405 kmem_update_timeout(void *dummy)
3406 {
3407 	(void) timeout(kmem_update, dummy, kmem_reap_interval);
3408 }
3409 
3410 static void
3411 kmem_update(void *dummy)
3412 {
3413 	kmem_cache_applyall(kmem_cache_update, NULL, TQ_NOSLEEP);
3414 
3415 	/*
3416 	 * We use taskq_dispatch() to reschedule the timeout so that
3417 	 * kmem_update() becomes self-throttling: it won't schedule
3418 	 * new tasks until all previous tasks have completed.
3419 	 */
3420 	if (taskq_dispatch(kmem_taskq, kmem_update_timeout, dummy, TQ_NOSLEEP)
3421 	    == TASKQID_INVALID)
3422 		kmem_update_timeout(NULL);
3423 }
3424 
3425 static int
3426 kmem_cache_kstat_update(kstat_t *ksp, int rw)
3427 {
3428 	struct kmem_cache_kstat *kmcp = &kmem_cache_kstat;
3429 	kmem_cache_t *cp = ksp->ks_private;
3430 	uint64_t cpu_buf_avail;
3431 	uint64_t buf_avail = 0;
3432 	int cpu_seqid;
3433 	long reap;
3434 
3435 	ASSERT(MUTEX_HELD(&kmem_cache_kstat_lock));
3436 
3437 	if (rw == KSTAT_WRITE)
3438 		return (EACCES);
3439 
3440 	mutex_enter(&cp->cache_lock);
3441 
3442 	kmcp->kmc_alloc_fail.value.ui64		= cp->cache_alloc_fail;
3443 	kmcp->kmc_alloc.value.ui64		= cp->cache_slab_alloc;
3444 	kmcp->kmc_free.value.ui64		= cp->cache_slab_free;
3445 	kmcp->kmc_slab_alloc.value.ui64		= cp->cache_slab_alloc;
3446 	kmcp->kmc_slab_free.value.ui64		= cp->cache_slab_free;
3447 
3448 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3449 		kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3450 
3451 		mutex_enter(&ccp->cc_lock);
3452 
3453 		cpu_buf_avail = 0;
3454 		if (ccp->cc_rounds > 0)
3455 			cpu_buf_avail += ccp->cc_rounds;
3456 		if (ccp->cc_prounds > 0)
3457 			cpu_buf_avail += ccp->cc_prounds;
3458 
3459 		kmcp->kmc_alloc.value.ui64	+= ccp->cc_alloc;
3460 		kmcp->kmc_free.value.ui64	+= ccp->cc_free;
3461 		buf_avail			+= cpu_buf_avail;
3462 
3463 		mutex_exit(&ccp->cc_lock);
3464 	}
3465 
3466 	mutex_enter(&cp->cache_depot_lock);
3467 
3468 	kmcp->kmc_depot_alloc.value.ui64	= cp->cache_full.ml_alloc;
3469 	kmcp->kmc_depot_free.value.ui64		= cp->cache_empty.ml_alloc;
3470 	kmcp->kmc_depot_contention.value.ui64	= cp->cache_depot_contention;
3471 	kmcp->kmc_full_magazines.value.ui64	= cp->cache_full.ml_total;
3472 	kmcp->kmc_empty_magazines.value.ui64	= cp->cache_empty.ml_total;
3473 	kmcp->kmc_magazine_size.value.ui64	=
3474 	    (cp->cache_flags & KMF_NOMAGAZINE) ?
3475 	    0 : cp->cache_magtype->mt_magsize;
3476 
3477 	kmcp->kmc_alloc.value.ui64		+= cp->cache_full.ml_alloc;
3478 	kmcp->kmc_free.value.ui64		+= cp->cache_empty.ml_alloc;
3479 	buf_avail += cp->cache_full.ml_total * cp->cache_magtype->mt_magsize;
3480 
3481 	reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
3482 	reap = MIN(reap, cp->cache_full.ml_total);
3483 
3484 	mutex_exit(&cp->cache_depot_lock);
3485 
3486 	kmcp->kmc_buf_size.value.ui64	= cp->cache_bufsize;
3487 	kmcp->kmc_align.value.ui64	= cp->cache_align;
3488 	kmcp->kmc_chunk_size.value.ui64	= cp->cache_chunksize;
3489 	kmcp->kmc_slab_size.value.ui64	= cp->cache_slabsize;
3490 	kmcp->kmc_buf_constructed.value.ui64 = buf_avail;
3491 	buf_avail += cp->cache_bufslab;
3492 	kmcp->kmc_buf_avail.value.ui64	= buf_avail;
3493 	kmcp->kmc_buf_inuse.value.ui64	= cp->cache_buftotal - buf_avail;
3494 	kmcp->kmc_buf_total.value.ui64	= cp->cache_buftotal;
3495 	kmcp->kmc_buf_max.value.ui64	= cp->cache_bufmax;
3496 	kmcp->kmc_slab_create.value.ui64	= cp->cache_slab_create;
3497 	kmcp->kmc_slab_destroy.value.ui64	= cp->cache_slab_destroy;
3498 	kmcp->kmc_hash_size.value.ui64	= (cp->cache_flags & KMF_HASH) ?
3499 	    cp->cache_hash_mask + 1 : 0;
3500 	kmcp->kmc_hash_lookup_depth.value.ui64	= cp->cache_lookup_depth;
3501 	kmcp->kmc_hash_rescale.value.ui64	= cp->cache_rescale;
3502 	kmcp->kmc_vmem_source.value.ui64	= cp->cache_arena->vm_id;
3503 	kmcp->kmc_reap.value.ui64	= cp->cache_reap;
3504 
3505 	if (cp->cache_defrag == NULL) {
3506 		kmcp->kmc_move_callbacks.value.ui64	= 0;
3507 		kmcp->kmc_move_yes.value.ui64		= 0;
3508 		kmcp->kmc_move_no.value.ui64		= 0;
3509 		kmcp->kmc_move_later.value.ui64		= 0;
3510 		kmcp->kmc_move_dont_need.value.ui64	= 0;
3511 		kmcp->kmc_move_dont_know.value.ui64	= 0;
3512 		kmcp->kmc_move_hunt_found.value.ui64	= 0;
3513 		kmcp->kmc_move_slabs_freed.value.ui64	= 0;
3514 		kmcp->kmc_defrag.value.ui64		= 0;
3515 		kmcp->kmc_scan.value.ui64		= 0;
3516 		kmcp->kmc_move_reclaimable.value.ui64	= 0;
3517 	} else {
3518 		int64_t reclaimable;
3519 
3520 		kmem_defrag_t *kd = cp->cache_defrag;
3521 		kmcp->kmc_move_callbacks.value.ui64	= kd->kmd_callbacks;
3522 		kmcp->kmc_move_yes.value.ui64		= kd->kmd_yes;
3523 		kmcp->kmc_move_no.value.ui64		= kd->kmd_no;
3524 		kmcp->kmc_move_later.value.ui64		= kd->kmd_later;
3525 		kmcp->kmc_move_dont_need.value.ui64	= kd->kmd_dont_need;
3526 		kmcp->kmc_move_dont_know.value.ui64	= kd->kmd_dont_know;
3527 		kmcp->kmc_move_hunt_found.value.ui64	= 0;
3528 		kmcp->kmc_move_slabs_freed.value.ui64	= kd->kmd_slabs_freed;
3529 		kmcp->kmc_defrag.value.ui64		= kd->kmd_defrags;
3530 		kmcp->kmc_scan.value.ui64		= kd->kmd_scans;
3531 
3532 		reclaimable = cp->cache_bufslab - (cp->cache_maxchunks - 1);
3533 		reclaimable = MAX(reclaimable, 0);
3534 		reclaimable += ((uint64_t)reap * cp->cache_magtype->mt_magsize);
3535 		kmcp->kmc_move_reclaimable.value.ui64	= reclaimable;
3536 	}
3537 
3538 	mutex_exit(&cp->cache_lock);
3539 	return (0);
3540 }
3541 
3542 /*
3543  * Return a named statistic about a particular cache.
3544  * This shouldn't be called very often, so it's currently designed for
3545  * simplicity (leverages existing kstat support) rather than efficiency.
3546  */
3547 uint64_t
3548 kmem_cache_stat(kmem_cache_t *cp, char *name)
3549 {
3550 	int i;
3551 	kstat_t *ksp = cp->cache_kstat;
3552 	kstat_named_t *knp = (kstat_named_t *)&kmem_cache_kstat;
3553 	uint64_t value = 0;
3554 
3555 	if (ksp != NULL) {
3556 		mutex_enter(&kmem_cache_kstat_lock);
3557 		(void) kmem_cache_kstat_update(ksp, KSTAT_READ);
3558 		for (i = 0; i < ksp->ks_ndata; i++) {
3559 			if (strcmp(knp[i].name, name) == 0) {
3560 				value = knp[i].value.ui64;
3561 				break;
3562 			}
3563 		}
3564 		mutex_exit<