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21 /*
22 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
24 * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
25 */
26
27 /*
28 * Kernel memory allocator, as described in the following two papers and a
29 * statement about the consolidator:
30 *
31 * Jeff Bonwick,
32 * The Slab Allocator: An Object-Caching Kernel Memory Allocator.
33 * Proceedings of the Summer 1994 Usenix Conference.
34 * Available as /shared/sac/PSARC/1994/028/materials/kmem.pdf.
35 *
36 * Jeff Bonwick and Jonathan Adams,
37 * Magazines and vmem: Extending the Slab Allocator to Many CPUs and
38 * Arbitrary Resources.
39 * Proceedings of the 2001 Usenix Conference.
40 * Available as /shared/sac/PSARC/2000/550/materials/vmem.pdf.
41 *
42 * kmem Slab Consolidator Big Theory Statement:
43 *
44 * 1. Motivation
45 *
46 * As stated in Bonwick94, slabs provide the following advantages over other
47 * allocation structures in terms of memory fragmentation:
48 *
49 * - Internal fragmentation (per-buffer wasted space) is minimal.
50 * - Severe external fragmentation (unused buffers on the free list) is
51 * unlikely.
52 *
53 * Segregating objects by size eliminates one source of external fragmentation,
54 * and according to Bonwick:
55 *
56 * The other reason that slabs reduce external fragmentation is that all
57 * objects in a slab are of the same type, so they have the same lifetime
58 * distribution. The resulting segregation of short-lived and long-lived
59 * objects at slab granularity reduces the likelihood of an entire page being
60 * held hostage due to a single long-lived allocation [Barrett93, Hanson90].
61 *
62 * While unlikely, severe external fragmentation remains possible. Clients that
63 * allocate both short- and long-lived objects from the same cache cannot
64 * anticipate the distribution of long-lived objects within the allocator's slab
65 * implementation. Even a small percentage of long-lived objects distributed
66 * randomly across many slabs can lead to a worst case scenario where the client
67 * frees the majority of its objects and the system gets back almost none of the
68 * slabs. Despite the client doing what it reasonably can to help the system
69 * reclaim memory, the allocator cannot shake free enough slabs because of
70 * lonely allocations stubbornly hanging on. Although the allocator is in a
71 * position to diagnose the fragmentation, there is nothing that the allocator
72 * by itself can do about it. It only takes a single allocated object to prevent
73 * an entire slab from being reclaimed, and any object handed out by
74 * kmem_cache_alloc() is by definition in the client's control. Conversely,
75 * although the client is in a position to move a long-lived object, it has no
76 * way of knowing if the object is causing fragmentation, and if so, where to
77 * move it. A solution necessarily requires further cooperation between the
78 * allocator and the client.
79 *
80 * 2. Move Callback
81 *
82 * The kmem slab consolidator therefore adds a move callback to the
83 * allocator/client interface, improving worst-case external fragmentation in
84 * kmem caches that supply a function to move objects from one memory location
85 * to another. In a situation of low memory kmem attempts to consolidate all of
86 * a cache's slabs at once; otherwise it works slowly to bring external
87 * fragmentation within the 1/8 limit guaranteed for internal fragmentation,
88 * thereby helping to avoid a low memory situation in the future.
89 *
90 * The callback has the following signature:
91 *
92 * kmem_cbrc_t move(void *old, void *new, size_t size, void *user_arg)
93 *
94 * It supplies the kmem client with two addresses: the allocated object that
95 * kmem wants to move and a buffer selected by kmem for the client to use as the
96 * copy destination. The callback is kmem's way of saying "Please get off of
97 * this buffer and use this one instead." kmem knows where it wants to move the
98 * object in order to best reduce fragmentation. All the client needs to know
99 * about the second argument (void *new) is that it is an allocated, constructed
100 * object ready to take the contents of the old object. When the move function
101 * is called, the system is likely to be low on memory, and the new object
102 * spares the client from having to worry about allocating memory for the
103 * requested move. The third argument supplies the size of the object, in case a
104 * single move function handles multiple caches whose objects differ only in
105 * size (such as zio_buf_512, zio_buf_1024, etc). Finally, the same optional
106 * user argument passed to the constructor, destructor, and reclaim functions is
107 * also passed to the move callback.
108 *
109 * 2.1 Setting the Move Callback
110 *
111 * The client sets the move callback after creating the cache and before
112 * allocating from it:
113 *
114 * object_cache = kmem_cache_create(...);
115 * kmem_cache_set_move(object_cache, object_move);
116 *
117 * 2.2 Move Callback Return Values
118 *
119 * Only the client knows about its own data and when is a good time to move it.
120 * The client is cooperating with kmem to return unused memory to the system,
121 * and kmem respectfully accepts this help at the client's convenience. When
122 * asked to move an object, the client can respond with any of the following:
123 *
124 * typedef enum kmem_cbrc {
125 * KMEM_CBRC_YES,
126 * KMEM_CBRC_NO,
127 * KMEM_CBRC_LATER,
128 * KMEM_CBRC_DONT_NEED,
129 * KMEM_CBRC_DONT_KNOW
130 * } kmem_cbrc_t;
131 *
132 * The client must not explicitly kmem_cache_free() either of the objects passed
133 * to the callback, since kmem wants to free them directly to the slab layer
134 * (bypassing the per-CPU magazine layer). The response tells kmem which of the
135 * objects to free:
136 *
137 * YES: (Did it) The client moved the object, so kmem frees the old one.
138 * NO: (Never) The client refused, so kmem frees the new object (the
139 * unused copy destination). kmem also marks the slab of the old
140 * object so as not to bother the client with further callbacks for
141 * that object as long as the slab remains on the partial slab list.
142 * (The system won't be getting the slab back as long as the
143 * immovable object holds it hostage, so there's no point in moving
144 * any of its objects.)
145 * LATER: The client is using the object and cannot move it now, so kmem
146 * frees the new object (the unused copy destination). kmem still
147 * attempts to move other objects off the slab, since it expects to
148 * succeed in clearing the slab in a later callback. The client
149 * should use LATER instead of NO if the object is likely to become
150 * movable very soon.
151 * DONT_NEED: The client no longer needs the object, so kmem frees the old along
152 * with the new object (the unused copy destination). This response
153 * is the client's opportunity to be a model citizen and give back as
154 * much as it can.
155 * DONT_KNOW: The client does not know about the object because
156 * a) the client has just allocated the object and not yet put it
157 * wherever it expects to find known objects
158 * b) the client has removed the object from wherever it expects to
159 * find known objects and is about to free it, or
160 * c) the client has freed the object.
161 * In all these cases (a, b, and c) kmem frees the new object (the
162 * unused copy destination). In the first case, the object is in
163 * use and the correct action is that for LATER; in the latter two
164 * cases, we know that the object is either freed or about to be
165 * freed, in which case it is either already in a magazine or about
166 * to be in one. In these cases, we know that the object will either
167 * be reallocated and reused, or it will end up in a full magazine
168 * that will be reaped (thereby liberating the slab). Because it
169 * is prohibitively expensive to differentiate these cases, and
170 * because the defrag code is executed when we're low on memory
171 * (thereby biasing the system to reclaim full magazines) we treat
172 * all DONT_KNOW cases as LATER and rely on cache reaping to
173 * generally clean up full magazines. While we take the same action
174 * for these cases, we maintain their semantic distinction: if
175 * defragmentation is not occurring, it is useful to know if this
176 * is due to objects in use (LATER) or objects in an unknown state
177 * of transition (DONT_KNOW).
178 *
179 * 2.3 Object States
180 *
181 * Neither kmem nor the client can be assumed to know the object's whereabouts
182 * at the time of the callback. An object belonging to a kmem cache may be in
183 * any of the following states:
184 *
185 * 1. Uninitialized on the slab
186 * 2. Allocated from the slab but not constructed (still uninitialized)
187 * 3. Allocated from the slab, constructed, but not yet ready for business
188 * (not in a valid state for the move callback)
189 * 4. In use (valid and known to the client)
190 * 5. About to be freed (no longer in a valid state for the move callback)
191 * 6. Freed to a magazine (still constructed)
192 * 7. Allocated from a magazine, not yet ready for business (not in a valid
193 * state for the move callback), and about to return to state #4
194 * 8. Deconstructed on a magazine that is about to be freed
195 * 9. Freed to the slab
196 *
197 * Since the move callback may be called at any time while the object is in any
198 * of the above states (except state #1), the client needs a safe way to
199 * determine whether or not it knows about the object. Specifically, the client
200 * needs to know whether or not the object is in state #4, the only state in
201 * which a move is valid. If the object is in any other state, the client should
202 * immediately return KMEM_CBRC_DONT_KNOW, since it is unsafe to access any of
203 * the object's fields.
204 *
205 * Note that although an object may be in state #4 when kmem initiates the move
206 * request, the object may no longer be in that state by the time kmem actually
207 * calls the move function. Not only does the client free objects
208 * asynchronously, kmem itself puts move requests on a queue where thay are
209 * pending until kmem processes them from another context. Also, objects freed
210 * to a magazine appear allocated from the point of view of the slab layer, so
211 * kmem may even initiate requests for objects in a state other than state #4.
212 *
213 * 2.3.1 Magazine Layer
214 *
215 * An important insight revealed by the states listed above is that the magazine
216 * layer is populated only by kmem_cache_free(). Magazines of constructed
217 * objects are never populated directly from the slab layer (which contains raw,
218 * unconstructed objects). Whenever an allocation request cannot be satisfied
219 * from the magazine layer, the magazines are bypassed and the request is
220 * satisfied from the slab layer (creating a new slab if necessary). kmem calls
221 * the object constructor only when allocating from the slab layer, and only in
222 * response to kmem_cache_alloc() or to prepare the destination buffer passed in
223 * the move callback. kmem does not preconstruct objects in anticipation of
224 * kmem_cache_alloc().
225 *
226 * 2.3.2 Object Constructor and Destructor
227 *
228 * If the client supplies a destructor, it must be valid to call the destructor
229 * on a newly created object (immediately after the constructor).
230 *
231 * 2.4 Recognizing Known Objects
232 *
233 * There is a simple test to determine safely whether or not the client knows
234 * about a given object in the move callback. It relies on the fact that kmem
235 * guarantees that the object of the move callback has only been touched by the
236 * client itself or else by kmem. kmem does this by ensuring that none of the
237 * cache's slabs are freed to the virtual memory (VM) subsystem while a move
238 * callback is pending. When the last object on a slab is freed, if there is a
239 * pending move, kmem puts the slab on a per-cache dead list and defers freeing
240 * slabs on that list until all pending callbacks are completed. That way,
241 * clients can be certain that the object of a move callback is in one of the
242 * states listed above, making it possible to distinguish known objects (in
243 * state #4) using the two low order bits of any pointer member (with the
244 * exception of 'char *' or 'short *' which may not be 4-byte aligned on some
245 * platforms).
246 *
247 * The test works as long as the client always transitions objects from state #4
248 * (known, in use) to state #5 (about to be freed, invalid) by setting the low
249 * order bit of the client-designated pointer member. Since kmem only writes
250 * invalid memory patterns, such as 0xbaddcafe to uninitialized memory and
251 * 0xdeadbeef to freed memory, any scribbling on the object done by kmem is
252 * guaranteed to set at least one of the two low order bits. Therefore, given an
253 * object with a back pointer to a 'container_t *o_container', the client can
254 * test
255 *
256 * container_t *container = object->o_container;
257 * if ((uintptr_t)container & 0x3) {
258 * return (KMEM_CBRC_DONT_KNOW);
259 * }
260 *
261 * Typically, an object will have a pointer to some structure with a list or
262 * hash where objects from the cache are kept while in use. Assuming that the
263 * client has some way of knowing that the container structure is valid and will
264 * not go away during the move, and assuming that the structure includes a lock
265 * to protect whatever collection is used, then the client would continue as
266 * follows:
267 *
268 * // Ensure that the container structure does not go away.
269 * if (container_hold(container) == 0) {
270 * return (KMEM_CBRC_DONT_KNOW);
271 * }
272 * mutex_enter(&container->c_objects_lock);
273 * if (container != object->o_container) {
274 * mutex_exit(&container->c_objects_lock);
275 * container_rele(container);
276 * return (KMEM_CBRC_DONT_KNOW);
277 * }
278 *
279 * At this point the client knows that the object cannot be freed as long as
280 * c_objects_lock is held. Note that after acquiring the lock, the client must
281 * recheck the o_container pointer in case the object was removed just before
282 * acquiring the lock.
283 *
284 * When the client is about to free an object, it must first remove that object
285 * from the list, hash, or other structure where it is kept. At that time, to
286 * mark the object so it can be distinguished from the remaining, known objects,
287 * the client sets the designated low order bit:
288 *
289 * mutex_enter(&container->c_objects_lock);
290 * object->o_container = (void *)((uintptr_t)object->o_container | 0x1);
291 * list_remove(&container->c_objects, object);
292 * mutex_exit(&container->c_objects_lock);
293 *
294 * In the common case, the object is freed to the magazine layer, where it may
295 * be reused on a subsequent allocation without the overhead of calling the
296 * constructor. While in the magazine it appears allocated from the point of
297 * view of the slab layer, making it a candidate for the move callback. Most
298 * objects unrecognized by the client in the move callback fall into this
299 * category and are cheaply distinguished from known objects by the test
300 * described earlier. Because searching magazines is prohibitively expensive
301 * for kmem, clients that do not mark freed objects (and therefore return
302 * KMEM_CBRC_DONT_KNOW for large numbers of objects) may find defragmentation
303 * efficacy reduced.
304 *
305 * Invalidating the designated pointer member before freeing the object marks
306 * the object to be avoided in the callback, and conversely, assigning a valid
307 * value to the designated pointer member after allocating the object makes the
308 * object fair game for the callback:
309 *
310 * ... allocate object ...
311 * ... set any initial state not set by the constructor ...
312 *
313 * mutex_enter(&container->c_objects_lock);
314 * list_insert_tail(&container->c_objects, object);
315 * membar_producer();
316 * object->o_container = container;
317 * mutex_exit(&container->c_objects_lock);
318 *
319 * Note that everything else must be valid before setting o_container makes the
320 * object fair game for the move callback. The membar_producer() call ensures
321 * that all the object's state is written to memory before setting the pointer
322 * that transitions the object from state #3 or #7 (allocated, constructed, not
323 * yet in use) to state #4 (in use, valid). That's important because the move
324 * function has to check the validity of the pointer before it can safely
325 * acquire the lock protecting the collection where it expects to find known
326 * objects.
327 *
328 * This method of distinguishing known objects observes the usual symmetry:
329 * invalidating the designated pointer is the first thing the client does before
330 * freeing the object, and setting the designated pointer is the last thing the
331 * client does after allocating the object. Of course, the client is not
332 * required to use this method. Fundamentally, how the client recognizes known
333 * objects is completely up to the client, but this method is recommended as an
334 * efficient and safe way to take advantage of the guarantees made by kmem. If
335 * the entire object is arbitrary data without any markable bits from a suitable
336 * pointer member, then the client must find some other method, such as
337 * searching a hash table of known objects.
338 *
339 * 2.5 Preventing Objects From Moving
340 *
341 * Besides a way to distinguish known objects, the other thing that the client
342 * needs is a strategy to ensure that an object will not move while the client
343 * is actively using it. The details of satisfying this requirement tend to be
344 * highly cache-specific. It might seem that the same rules that let a client
345 * remove an object safely should also decide when an object can be moved
346 * safely. However, any object state that makes a removal attempt invalid is
347 * likely to be long-lasting for objects that the client does not expect to
348 * remove. kmem knows nothing about the object state and is equally likely (from
349 * the client's point of view) to request a move for any object in the cache,
350 * whether prepared for removal or not. Even a low percentage of objects stuck
351 * in place by unremovability will defeat the consolidator if the stuck objects
352 * are the same long-lived allocations likely to hold slabs hostage.
353 * Fundamentally, the consolidator is not aimed at common cases. Severe external
354 * fragmentation is a worst case scenario manifested as sparsely allocated
355 * slabs, by definition a low percentage of the cache's objects. When deciding
356 * what makes an object movable, keep in mind the goal of the consolidator: to
357 * bring worst-case external fragmentation within the limits guaranteed for
358 * internal fragmentation. Removability is a poor criterion if it is likely to
359 * exclude more than an insignificant percentage of objects for long periods of
360 * time.
361 *
362 * A tricky general solution exists, and it has the advantage of letting you
363 * move any object at almost any moment, practically eliminating the likelihood
364 * that an object can hold a slab hostage. However, if there is a cache-specific
365 * way to ensure that an object is not actively in use in the vast majority of
366 * cases, a simpler solution that leverages this cache-specific knowledge is
367 * preferred.
368 *
369 * 2.5.1 Cache-Specific Solution
370 *
371 * As an example of a cache-specific solution, the ZFS znode cache takes
372 * advantage of the fact that the vast majority of znodes are only being
373 * referenced from the DNLC. (A typical case might be a few hundred in active
374 * use and a hundred thousand in the DNLC.) In the move callback, after the ZFS
375 * client has established that it recognizes the znode and can access its fields
376 * safely (using the method described earlier), it then tests whether the znode
377 * is referenced by anything other than the DNLC. If so, it assumes that the
378 * znode may be in active use and is unsafe to move, so it drops its locks and
379 * returns KMEM_CBRC_LATER. The advantage of this strategy is that everywhere
380 * else znodes are used, no change is needed to protect against the possibility
381 * of the znode moving. The disadvantage is that it remains possible for an
382 * application to hold a znode slab hostage with an open file descriptor.
383 * However, this case ought to be rare and the consolidator has a way to deal
384 * with it: If the client responds KMEM_CBRC_LATER repeatedly for the same
385 * object, kmem eventually stops believing it and treats the slab as if the
386 * client had responded KMEM_CBRC_NO. Having marked the hostage slab, kmem can
387 * then focus on getting it off of the partial slab list by allocating rather
388 * than freeing all of its objects. (Either way of getting a slab off the
389 * free list reduces fragmentation.)
390 *
391 * 2.5.2 General Solution
392 *
393 * The general solution, on the other hand, requires an explicit hold everywhere
394 * the object is used to prevent it from moving. To keep the client locking
395 * strategy as uncomplicated as possible, kmem guarantees the simplifying
396 * assumption that move callbacks are sequential, even across multiple caches.
397 * Internally, a global queue processed by a single thread supports all caches
398 * implementing the callback function. No matter how many caches supply a move
399 * function, the consolidator never moves more than one object at a time, so the
400 * client does not have to worry about tricky lock ordering involving several
401 * related objects from different kmem caches.
402 *
403 * The general solution implements the explicit hold as a read-write lock, which
404 * allows multiple readers to access an object from the cache simultaneously
405 * while a single writer is excluded from moving it. A single rwlock for the
406 * entire cache would lock out all threads from using any of the cache's objects
407 * even though only a single object is being moved, so to reduce contention,
408 * the client can fan out the single rwlock into an array of rwlocks hashed by
409 * the object address, making it probable that moving one object will not
410 * prevent other threads from using a different object. The rwlock cannot be a
411 * member of the object itself, because the possibility of the object moving
412 * makes it unsafe to access any of the object's fields until the lock is
413 * acquired.
414 *
415 * Assuming a small, fixed number of locks, it's possible that multiple objects
416 * will hash to the same lock. A thread that needs to use multiple objects in
417 * the same function may acquire the same lock multiple times. Since rwlocks are
418 * reentrant for readers, and since there is never more than a single writer at
419 * a time (assuming that the client acquires the lock as a writer only when
420 * moving an object inside the callback), there would seem to be no problem.
421 * However, a client locking multiple objects in the same function must handle
422 * one case of potential deadlock: Assume that thread A needs to prevent both
423 * object 1 and object 2 from moving, and thread B, the callback, meanwhile
424 * tries to move object 3. It's possible, if objects 1, 2, and 3 all hash to the
425 * same lock, that thread A will acquire the lock for object 1 as a reader
426 * before thread B sets the lock's write-wanted bit, preventing thread A from
427 * reacquiring the lock for object 2 as a reader. Unable to make forward
428 * progress, thread A will never release the lock for object 1, resulting in
429 * deadlock.
430 *
431 * There are two ways of avoiding the deadlock just described. The first is to
432 * use rw_tryenter() rather than rw_enter() in the callback function when
433 * attempting to acquire the lock as a writer. If tryenter discovers that the
434 * same object (or another object hashed to the same lock) is already in use, it
435 * aborts the callback and returns KMEM_CBRC_LATER. The second way is to use
436 * rprwlock_t (declared in common/fs/zfs/sys/rprwlock.h) instead of rwlock_t,
437 * since it allows a thread to acquire the lock as a reader in spite of a
438 * waiting writer. This second approach insists on moving the object now, no
439 * matter how many readers the move function must wait for in order to do so,
440 * and could delay the completion of the callback indefinitely (blocking
441 * callbacks to other clients). In practice, a less insistent callback using
442 * rw_tryenter() returns KMEM_CBRC_LATER infrequently enough that there seems
443 * little reason to use anything else.
444 *
445 * Avoiding deadlock is not the only problem that an implementation using an
446 * explicit hold needs to solve. Locking the object in the first place (to
447 * prevent it from moving) remains a problem, since the object could move
448 * between the time you obtain a pointer to the object and the time you acquire
449 * the rwlock hashed to that pointer value. Therefore the client needs to
450 * recheck the value of the pointer after acquiring the lock, drop the lock if
451 * the value has changed, and try again. This requires a level of indirection:
452 * something that points to the object rather than the object itself, that the
453 * client can access safely while attempting to acquire the lock. (The object
454 * itself cannot be referenced safely because it can move at any time.)
455 * The following lock-acquisition function takes whatever is safe to reference
456 * (arg), follows its pointer to the object (using function f), and tries as
457 * often as necessary to acquire the hashed lock and verify that the object
458 * still has not moved:
459 *
460 * object_t *
461 * object_hold(object_f f, void *arg)
462 * {
463 * object_t *op;
464 *
465 * op = f(arg);
466 * if (op == NULL) {
467 * return (NULL);
468 * }
469 *
470 * rw_enter(OBJECT_RWLOCK(op), RW_READER);
471 * while (op != f(arg)) {
472 * rw_exit(OBJECT_RWLOCK(op));
473 * op = f(arg);
474 * if (op == NULL) {
475 * break;
476 * }
477 * rw_enter(OBJECT_RWLOCK(op), RW_READER);
478 * }
479 *
480 * return (op);
481 * }
482 *
483 * The OBJECT_RWLOCK macro hashes the object address to obtain the rwlock. The
484 * lock reacquisition loop, while necessary, almost never executes. The function
485 * pointer f (used to obtain the object pointer from arg) has the following type
486 * definition:
487 *
488 * typedef object_t *(*object_f)(void *arg);
489 *
490 * An object_f implementation is likely to be as simple as accessing a structure
491 * member:
492 *
493 * object_t *
494 * s_object(void *arg)
495 * {
496 * something_t *sp = arg;
497 * return (sp->s_object);
498 * }
499 *
500 * The flexibility of a function pointer allows the path to the object to be
501 * arbitrarily complex and also supports the notion that depending on where you
502 * are using the object, you may need to get it from someplace different.
503 *
504 * The function that releases the explicit hold is simpler because it does not
505 * have to worry about the object moving:
506 *
507 * void
508 * object_rele(object_t *op)
509 * {
510 * rw_exit(OBJECT_RWLOCK(op));
511 * }
512 *
513 * The caller is spared these details so that obtaining and releasing an
514 * explicit hold feels like a simple mutex_enter()/mutex_exit() pair. The caller
515 * of object_hold() only needs to know that the returned object pointer is valid
516 * if not NULL and that the object will not move until released.
517 *
518 * Although object_hold() prevents an object from moving, it does not prevent it
519 * from being freed. The caller must take measures before calling object_hold()
520 * (afterwards is too late) to ensure that the held object cannot be freed. The
521 * caller must do so without accessing the unsafe object reference, so any lock
522 * or reference count used to ensure the continued existence of the object must
523 * live outside the object itself.
524 *
525 * Obtaining a new object is a special case where an explicit hold is impossible
526 * for the caller. Any function that returns a newly allocated object (either as
527 * a return value, or as an in-out paramter) must return it already held; after
528 * the caller gets it is too late, since the object cannot be safely accessed
529 * without the level of indirection described earlier. The following
530 * object_alloc() example uses the same code shown earlier to transition a new
531 * object into the state of being recognized (by the client) as a known object.
532 * The function must acquire the hold (rw_enter) before that state transition
533 * makes the object movable:
534 *
535 * static object_t *
536 * object_alloc(container_t *container)
537 * {
538 * object_t *object = kmem_cache_alloc(object_cache, 0);
539 * ... set any initial state not set by the constructor ...
540 * rw_enter(OBJECT_RWLOCK(object), RW_READER);
541 * mutex_enter(&container->c_objects_lock);
542 * list_insert_tail(&container->c_objects, object);
543 * membar_producer();
544 * object->o_container = container;
545 * mutex_exit(&container->c_objects_lock);
546 * return (object);
547 * }
548 *
549 * Functions that implicitly acquire an object hold (any function that calls
550 * object_alloc() to supply an object for the caller) need to be carefully noted
551 * so that the matching object_rele() is not neglected. Otherwise, leaked holds
552 * prevent all objects hashed to the affected rwlocks from ever being moved.
553 *
554 * The pointer to a held object can be hashed to the holding rwlock even after
555 * the object has been freed. Although it is possible to release the hold
556 * after freeing the object, you may decide to release the hold implicitly in
557 * whatever function frees the object, so as to release the hold as soon as
558 * possible, and for the sake of symmetry with the function that implicitly
559 * acquires the hold when it allocates the object. Here, object_free() releases
560 * the hold acquired by object_alloc(). Its implicit object_rele() forms a
561 * matching pair with object_hold():
562 *
563 * void
564 * object_free(object_t *object)
565 * {
566 * container_t *container;
567 *
568 * ASSERT(object_held(object));
569 * container = object->o_container;
570 * mutex_enter(&container->c_objects_lock);
571 * object->o_container =
572 * (void *)((uintptr_t)object->o_container | 0x1);
573 * list_remove(&container->c_objects, object);
574 * mutex_exit(&container->c_objects_lock);
575 * object_rele(object);
576 * kmem_cache_free(object_cache, object);
577 * }
578 *
579 * Note that object_free() cannot safely accept an object pointer as an argument
580 * unless the object is already held. Any function that calls object_free()
581 * needs to be carefully noted since it similarly forms a matching pair with
582 * object_hold().
583 *
584 * To complete the picture, the following callback function implements the
585 * general solution by moving objects only if they are currently unheld:
586 *
587 * static kmem_cbrc_t
588 * object_move(void *buf, void *newbuf, size_t size, void *arg)
589 * {
590 * object_t *op = buf, *np = newbuf;
591 * container_t *container;
592 *
593 * container = op->o_container;
594 * if ((uintptr_t)container & 0x3) {
595 * return (KMEM_CBRC_DONT_KNOW);
596 * }
597 *
598 * // Ensure that the container structure does not go away.
599 * if (container_hold(container) == 0) {
600 * return (KMEM_CBRC_DONT_KNOW);
601 * }
602 *
603 * mutex_enter(&container->c_objects_lock);
604 * if (container != op->o_container) {
605 * mutex_exit(&container->c_objects_lock);
606 * container_rele(container);
607 * return (KMEM_CBRC_DONT_KNOW);
608 * }
609 *
610 * if (rw_tryenter(OBJECT_RWLOCK(op), RW_WRITER) == 0) {
611 * mutex_exit(&container->c_objects_lock);
612 * container_rele(container);
613 * return (KMEM_CBRC_LATER);
614 * }
615 *
616 * object_move_impl(op, np); // critical section
617 * rw_exit(OBJECT_RWLOCK(op));
618 *
619 * op->o_container = (void *)((uintptr_t)op->o_container | 0x1);
620 * list_link_replace(&op->o_link_node, &np->o_link_node);
621 * mutex_exit(&container->c_objects_lock);
622 * container_rele(container);
623 * return (KMEM_CBRC_YES);
624 * }
625 *
626 * Note that object_move() must invalidate the designated o_container pointer of
627 * the old object in the same way that object_free() does, since kmem will free
628 * the object in response to the KMEM_CBRC_YES return value.
629 *
630 * The lock order in object_move() differs from object_alloc(), which locks
631 * OBJECT_RWLOCK first and &container->c_objects_lock second, but as long as the
632 * callback uses rw_tryenter() (preventing the deadlock described earlier), it's
633 * not a problem. Holding the lock on the object list in the example above
634 * through the entire callback not only prevents the object from going away, it
635 * also allows you to lock the list elsewhere and know that none of its elements
636 * will move during iteration.
637 *
638 * Adding an explicit hold everywhere an object from the cache is used is tricky
639 * and involves much more change to client code than a cache-specific solution
640 * that leverages existing state to decide whether or not an object is
641 * movable. However, this approach has the advantage that no object remains
642 * immovable for any significant length of time, making it extremely unlikely
643 * that long-lived allocations can continue holding slabs hostage; and it works
644 * for any cache.
645 *
646 * 3. Consolidator Implementation
647 *
648 * Once the client supplies a move function that a) recognizes known objects and
649 * b) avoids moving objects that are actively in use, the remaining work is up
650 * to the consolidator to decide which objects to move and when to issue
651 * callbacks.
652 *
653 * The consolidator relies on the fact that a cache's slabs are ordered by
654 * usage. Each slab has a fixed number of objects. Depending on the slab's
655 * "color" (the offset of the first object from the beginning of the slab;
656 * offsets are staggered to mitigate false sharing of cache lines) it is either
657 * the maximum number of objects per slab determined at cache creation time or
658 * else the number closest to the maximum that fits within the space remaining
659 * after the initial offset. A completely allocated slab may contribute some
660 * internal fragmentation (per-slab overhead) but no external fragmentation, so
661 * it is of no interest to the consolidator. At the other extreme, slabs whose
662 * objects have all been freed to the slab are released to the virtual memory
663 * (VM) subsystem (objects freed to magazines are still allocated as far as the
664 * slab is concerned). External fragmentation exists when there are slabs
665 * somewhere between these extremes. A partial slab has at least one but not all
666 * of its objects allocated. The more partial slabs, and the fewer allocated
667 * objects on each of them, the higher the fragmentation. Hence the
668 * consolidator's overall strategy is to reduce the number of partial slabs by
669 * moving allocated objects from the least allocated slabs to the most allocated
670 * slabs.
671 *
672 * Partial slabs are kept in an AVL tree ordered by usage. Completely allocated
673 * slabs are kept separately in an unordered list. Since the majority of slabs
674 * tend to be completely allocated (a typical unfragmented cache may have
675 * thousands of complete slabs and only a single partial slab), separating
676 * complete slabs improves the efficiency of partial slab ordering, since the
677 * complete slabs do not affect the depth or balance of the AVL tree. This
678 * ordered sequence of partial slabs acts as a "free list" supplying objects for
679 * allocation requests.
680 *
681 * Objects are always allocated from the first partial slab in the free list,
682 * where the allocation is most likely to eliminate a partial slab (by
683 * completely allocating it). Conversely, when a single object from a completely
684 * allocated slab is freed to the slab, that slab is added to the front of the
685 * free list. Since most free list activity involves highly allocated slabs
686 * coming and going at the front of the list, slabs tend naturally toward the
687 * ideal order: highly allocated at the front, sparsely allocated at the back.
688 * Slabs with few allocated objects are likely to become completely free if they
689 * keep a safe distance away from the front of the free list. Slab misorders
690 * interfere with the natural tendency of slabs to become completely free or
691 * completely allocated. For example, a slab with a single allocated object
692 * needs only a single free to escape the cache; its natural desire is
693 * frustrated when it finds itself at the front of the list where a second
694 * allocation happens just before the free could have released it. Another slab
695 * with all but one object allocated might have supplied the buffer instead, so
696 * that both (as opposed to neither) of the slabs would have been taken off the
697 * free list.
698 *
699 * Although slabs tend naturally toward the ideal order, misorders allowed by a
700 * simple list implementation defeat the consolidator's strategy of merging
701 * least- and most-allocated slabs. Without an AVL tree to guarantee order, kmem
702 * needs another way to fix misorders to optimize its callback strategy. One
703 * approach is to periodically scan a limited number of slabs, advancing a
704 * marker to hold the current scan position, and to move extreme misorders to
705 * the front or back of the free list and to the front or back of the current
706 * scan range. By making consecutive scan ranges overlap by one slab, the least
707 * allocated slab in the current range can be carried along from the end of one
708 * scan to the start of the next.
709 *
710 * Maintaining partial slabs in an AVL tree relieves kmem of this additional
711 * task, however. Since most of the cache's activity is in the magazine layer,
712 * and allocations from the slab layer represent only a startup cost, the
713 * overhead of maintaining a balanced tree is not a significant concern compared
714 * to the opportunity of reducing complexity by eliminating the partial slab
715 * scanner just described. The overhead of an AVL tree is minimized by
716 * maintaining only partial slabs in the tree and keeping completely allocated
717 * slabs separately in a list. To avoid increasing the size of the slab
718 * structure the AVL linkage pointers are reused for the slab's list linkage,
719 * since the slab will always be either partial or complete, never stored both
720 * ways at the same time. To further minimize the overhead of the AVL tree the
721 * compare function that orders partial slabs by usage divides the range of
722 * allocated object counts into bins such that counts within the same bin are
723 * considered equal. Binning partial slabs makes it less likely that allocating
724 * or freeing a single object will change the slab's order, requiring a tree
725 * reinsertion (an avl_remove() followed by an avl_add(), both potentially
726 * requiring some rebalancing of the tree). Allocation counts closest to
727 * completely free and completely allocated are left unbinned (finely sorted) to
728 * better support the consolidator's strategy of merging slabs at either
729 * extreme.
730 *
731 * 3.1 Assessing Fragmentation and Selecting Candidate Slabs
732 *
733 * The consolidator piggybacks on the kmem maintenance thread and is called on
734 * the same interval as kmem_cache_update(), once per cache every fifteen
735 * seconds. kmem maintains a running count of unallocated objects in the slab
736 * layer (cache_bufslab). The consolidator checks whether that number exceeds
737 * 12.5% (1/8) of the total objects in the cache (cache_buftotal), and whether
738 * there is a significant number of slabs in the cache (arbitrarily a minimum
739 * 101 total slabs). Unused objects that have fallen out of the magazine layer's
740 * working set are included in the assessment, and magazines in the depot are
741 * reaped if those objects would lift cache_bufslab above the fragmentation
742 * threshold. Once the consolidator decides that a cache is fragmented, it looks
743 * for a candidate slab to reclaim, starting at the end of the partial slab free
744 * list and scanning backwards. At first the consolidator is choosy: only a slab
745 * with fewer than 12.5% (1/8) of its objects allocated qualifies (or else a
746 * single allocated object, regardless of percentage). If there is difficulty
747 * finding a candidate slab, kmem raises the allocation threshold incrementally,
748 * up to a maximum 87.5% (7/8), so that eventually the consolidator will reduce
749 * external fragmentation (unused objects on the free list) below 12.5% (1/8),
750 * even in the worst case of every slab in the cache being almost 7/8 allocated.
751 * The threshold can also be lowered incrementally when candidate slabs are easy
752 * to find, and the threshold is reset to the minimum 1/8 as soon as the cache
753 * is no longer fragmented.
754 *
755 * 3.2 Generating Callbacks
756 *
757 * Once an eligible slab is chosen, a callback is generated for every allocated
758 * object on the slab, in the hope that the client will move everything off the
759 * slab and make it reclaimable. Objects selected as move destinations are
760 * chosen from slabs at the front of the free list. Assuming slabs in the ideal
761 * order (most allocated at the front, least allocated at the back) and a
762 * cooperative client, the consolidator will succeed in removing slabs from both
763 * ends of the free list, completely allocating on the one hand and completely
764 * freeing on the other. Objects selected as move destinations are allocated in
765 * the kmem maintenance thread where move requests are enqueued. A separate
766 * callback thread removes pending callbacks from the queue and calls the
767 * client. The separate thread ensures that client code (the move function) does
768 * not interfere with internal kmem maintenance tasks. A map of pending
769 * callbacks keyed by object address (the object to be moved) is checked to
770 * ensure that duplicate callbacks are not generated for the same object.
771 * Allocating the move destination (the object to move to) prevents subsequent
772 * callbacks from selecting the same destination as an earlier pending callback.
773 *
774 * Move requests can also be generated by kmem_cache_reap() when the system is
775 * desperate for memory and by kmem_cache_move_notify(), called by the client to
776 * notify kmem that a move refused earlier with KMEM_CBRC_LATER is now possible.
777 * The map of pending callbacks is protected by the same lock that protects the
778 * slab layer.
779 *
780 * When the system is desperate for memory, kmem does not bother to determine
781 * whether or not the cache exceeds the fragmentation threshold, but tries to
782 * consolidate as many slabs as possible. Normally, the consolidator chews
783 * slowly, one sparsely allocated slab at a time during each maintenance
784 * interval that the cache is fragmented. When desperate, the consolidator
785 * starts at the last partial slab and enqueues callbacks for every allocated
786 * object on every partial slab, working backwards until it reaches the first
787 * partial slab. The first partial slab, meanwhile, advances in pace with the
788 * consolidator as allocations to supply move destinations for the enqueued
789 * callbacks use up the highly allocated slabs at the front of the free list.
790 * Ideally, the overgrown free list collapses like an accordion, starting at
791 * both ends and ending at the center with a single partial slab.
792 *
793 * 3.3 Client Responses
794 *
795 * When the client returns KMEM_CBRC_NO in response to the move callback, kmem
796 * marks the slab that supplied the stuck object non-reclaimable and moves it to
797 * front of the free list. The slab remains marked as long as it remains on the
798 * free list, and it appears more allocated to the partial slab compare function
799 * than any unmarked slab, no matter how many of its objects are allocated.
800 * Since even one immovable object ties up the entire slab, the goal is to
801 * completely allocate any slab that cannot be completely freed. kmem does not
802 * bother generating callbacks to move objects from a marked slab unless the
803 * system is desperate.
804 *
805 * When the client responds KMEM_CBRC_LATER, kmem increments a count for the
806 * slab. If the client responds LATER too many times, kmem disbelieves and
807 * treats the response as a NO. The count is cleared when the slab is taken off
808 * the partial slab list or when the client moves one of the slab's objects.
809 *
810 * 4. Observability
811 *
812 * A kmem cache's external fragmentation is best observed with 'mdb -k' using
813 * the ::kmem_slabs dcmd. For a complete description of the command, enter
814 * '::help kmem_slabs' at the mdb prompt.
815 */
816
817 #include <sys/kmem_impl.h>
818 #include <sys/vmem_impl.h>
819 #include <sys/param.h>
820 #include <sys/sysmacros.h>
821 #include <sys/vm.h>
822 #include <sys/proc.h>
823 #include <sys/tuneable.h>
824 #include <sys/systm.h>
825 #include <sys/cmn_err.h>
826 #include <sys/debug.h>
827 #include <sys/sdt.h>
828 #include <sys/mutex.h>
829 #include <sys/bitmap.h>
830 #include <sys/atomic.h>
831 #include <sys/kobj.h>
832 #include <sys/disp.h>
833 #include <vm/seg_kmem.h>
834 #include <sys/log.h>
835 #include <sys/callb.h>
836 #include <sys/taskq.h>
837 #include <sys/modctl.h>
838 #include <sys/reboot.h>
839 #include <sys/id32.h>
840 #include <sys/zone.h>
841 #include <sys/netstack.h>
842 #ifdef DEBUG
843 #include <sys/random.h>
844 #endif
845
846 extern void streams_msg_init(void);
847 extern int segkp_fromheap;
848 extern void segkp_cache_free(void);
849 extern int callout_init_done;
850
851 struct kmem_cache_kstat {
852 kstat_named_t kmc_buf_size;
853 kstat_named_t kmc_align;
854 kstat_named_t kmc_chunk_size;
855 kstat_named_t kmc_slab_size;
856 kstat_named_t kmc_alloc;
857 kstat_named_t kmc_alloc_fail;
858 kstat_named_t kmc_free;
859 kstat_named_t kmc_depot_alloc;
860 kstat_named_t kmc_depot_free;
861 kstat_named_t kmc_depot_contention;
862 kstat_named_t kmc_slab_alloc;
863 kstat_named_t kmc_slab_free;
864 kstat_named_t kmc_buf_constructed;
865 kstat_named_t kmc_buf_avail;
866 kstat_named_t kmc_buf_inuse;
867 kstat_named_t kmc_buf_total;
868 kstat_named_t kmc_buf_max;
869 kstat_named_t kmc_slab_create;
870 kstat_named_t kmc_slab_destroy;
871 kstat_named_t kmc_vmem_source;
872 kstat_named_t kmc_hash_size;
873 kstat_named_t kmc_hash_lookup_depth;
874 kstat_named_t kmc_hash_rescale;
875 kstat_named_t kmc_full_magazines;
876 kstat_named_t kmc_empty_magazines;
877 kstat_named_t kmc_magazine_size;
878 kstat_named_t kmc_reap; /* number of kmem_cache_reap() calls */
879 kstat_named_t kmc_defrag; /* attempts to defrag all partial slabs */
880 kstat_named_t kmc_scan; /* attempts to defrag one partial slab */
881 kstat_named_t kmc_move_callbacks; /* sum of yes, no, later, dn, dk */
882 kstat_named_t kmc_move_yes;
883 kstat_named_t kmc_move_no;
884 kstat_named_t kmc_move_later;
885 kstat_named_t kmc_move_dont_need;
886 kstat_named_t kmc_move_dont_know; /* obj unrecognized by client ... */
887 kstat_named_t kmc_move_hunt_found; /* ... but found in mag layer */
888 kstat_named_t kmc_move_slabs_freed; /* slabs freed by consolidator */
889 kstat_named_t kmc_move_reclaimable; /* buffers, if consolidator ran */
890 } kmem_cache_kstat = {
891 { "buf_size", KSTAT_DATA_UINT64 },
892 { "align", KSTAT_DATA_UINT64 },
893 { "chunk_size", KSTAT_DATA_UINT64 },
894 { "slab_size", KSTAT_DATA_UINT64 },
895 { "alloc", KSTAT_DATA_UINT64 },
896 { "alloc_fail", KSTAT_DATA_UINT64 },
897 { "free", KSTAT_DATA_UINT64 },
898 { "depot_alloc", KSTAT_DATA_UINT64 },
899 { "depot_free", KSTAT_DATA_UINT64 },
900 { "depot_contention", KSTAT_DATA_UINT64 },
901 { "slab_alloc", KSTAT_DATA_UINT64 },
902 { "slab_free", KSTAT_DATA_UINT64 },
903 { "buf_constructed", KSTAT_DATA_UINT64 },
904 { "buf_avail", KSTAT_DATA_UINT64 },
905 { "buf_inuse", KSTAT_DATA_UINT64 },
906 { "buf_total", KSTAT_DATA_UINT64 },
907 { "buf_max", KSTAT_DATA_UINT64 },
908 { "slab_create", KSTAT_DATA_UINT64 },
909 { "slab_destroy", KSTAT_DATA_UINT64 },
910 { "vmem_source", KSTAT_DATA_UINT64 },
911 { "hash_size", KSTAT_DATA_UINT64 },
912 { "hash_lookup_depth", KSTAT_DATA_UINT64 },
913 { "hash_rescale", KSTAT_DATA_UINT64 },
914 { "full_magazines", KSTAT_DATA_UINT64 },
915 { "empty_magazines", KSTAT_DATA_UINT64 },
916 { "magazine_size", KSTAT_DATA_UINT64 },
917 { "reap", KSTAT_DATA_UINT64 },
918 { "defrag", KSTAT_DATA_UINT64 },
919 { "scan", KSTAT_DATA_UINT64 },
920 { "move_callbacks", KSTAT_DATA_UINT64 },
921 { "move_yes", KSTAT_DATA_UINT64 },
922 { "move_no", KSTAT_DATA_UINT64 },
923 { "move_later", KSTAT_DATA_UINT64 },
924 { "move_dont_need", KSTAT_DATA_UINT64 },
925 { "move_dont_know", KSTAT_DATA_UINT64 },
926 { "move_hunt_found", KSTAT_DATA_UINT64 },
927 { "move_slabs_freed", KSTAT_DATA_UINT64 },
928 { "move_reclaimable", KSTAT_DATA_UINT64 },
929 };
930
931 static kmutex_t kmem_cache_kstat_lock;
932
933 /*
934 * The default set of caches to back kmem_alloc().
935 * These sizes should be reevaluated periodically.
936 *
937 * We want allocations that are multiples of the coherency granularity
938 * (64 bytes) to be satisfied from a cache which is a multiple of 64
939 * bytes, so that it will be 64-byte aligned. For all multiples of 64,
940 * the next kmem_cache_size greater than or equal to it must be a
941 * multiple of 64.
942 *
943 * We split the table into two sections: size <= 4k and size > 4k. This
944 * saves a lot of space and cache footprint in our cache tables.
945 */
946 static const int kmem_alloc_sizes[] = {
947 1 * 8,
948 2 * 8,
949 3 * 8,
950 4 * 8, 5 * 8, 6 * 8, 7 * 8,
951 4 * 16, 5 * 16, 6 * 16, 7 * 16,
952 4 * 32, 5 * 32, 6 * 32, 7 * 32,
953 4 * 64, 5 * 64, 6 * 64, 7 * 64,
954 4 * 128, 5 * 128, 6 * 128, 7 * 128,
955 P2ALIGN(8192 / 7, 64),
956 P2ALIGN(8192 / 6, 64),
957 P2ALIGN(8192 / 5, 64),
958 P2ALIGN(8192 / 4, 64),
959 P2ALIGN(8192 / 3, 64),
960 P2ALIGN(8192 / 2, 64),
961 };
962
963 static const int kmem_big_alloc_sizes[] = {
964 2 * 4096, 3 * 4096,
965 2 * 8192, 3 * 8192,
966 4 * 8192, 5 * 8192, 6 * 8192, 7 * 8192,
967 8 * 8192, 9 * 8192, 10 * 8192, 11 * 8192,
968 12 * 8192, 13 * 8192, 14 * 8192, 15 * 8192,
969 16 * 8192
970 };
971
972 #define KMEM_MAXBUF 4096
973 #define KMEM_BIG_MAXBUF_32BIT 32768
974 #define KMEM_BIG_MAXBUF 131072
975
976 #define KMEM_BIG_MULTIPLE 4096 /* big_alloc_sizes must be a multiple */
977 #define KMEM_BIG_SHIFT 12 /* lg(KMEM_BIG_MULTIPLE) */
978
979 static kmem_cache_t *kmem_alloc_table[KMEM_MAXBUF >> KMEM_ALIGN_SHIFT];
980 static kmem_cache_t *kmem_big_alloc_table[KMEM_BIG_MAXBUF >> KMEM_BIG_SHIFT];
981
982 #define KMEM_ALLOC_TABLE_MAX (KMEM_MAXBUF >> KMEM_ALIGN_SHIFT)
983 static size_t kmem_big_alloc_table_max = 0; /* # of filled elements */
984
985 static kmem_magtype_t kmem_magtype[] = {
986 { 1, 8, 3200, 65536 },
987 { 3, 16, 256, 32768 },
988 { 7, 32, 64, 16384 },
989 { 15, 64, 0, 8192 },
990 { 31, 64, 0, 4096 },
991 { 47, 64, 0, 2048 },
992 { 63, 64, 0, 1024 },
993 { 95, 64, 0, 512 },
994 { 143, 64, 0, 0 },
995 };
996
997 static uint32_t kmem_reaping;
998 static uint32_t kmem_reaping_idspace;
999
1000 /*
1001 * kmem tunables
1002 */
1003 clock_t kmem_reap_interval; /* cache reaping rate [15 * HZ ticks] */
1004 int kmem_depot_contention = 3; /* max failed tryenters per real interval */
1005 pgcnt_t kmem_reapahead = 0; /* start reaping N pages before pageout */
1006 int kmem_panic = 1; /* whether to panic on error */
1007 int kmem_logging = 1; /* kmem_log_enter() override */
1008 uint32_t kmem_mtbf = 0; /* mean time between failures [default: off] */
1009 size_t kmem_transaction_log_size; /* transaction log size [2% of memory] */
1010 size_t kmem_content_log_size; /* content log size [2% of memory] */
1011 size_t kmem_failure_log_size; /* failure log [4 pages per CPU] */
1012 size_t kmem_slab_log_size; /* slab create log [4 pages per CPU] */
1013 size_t kmem_content_maxsave = 256; /* KMF_CONTENTS max bytes to log */
1014 size_t kmem_lite_minsize = 0; /* minimum buffer size for KMF_LITE */
1015 size_t kmem_lite_maxalign = 1024; /* maximum buffer alignment for KMF_LITE */
1016 int kmem_lite_pcs = 4; /* number of PCs to store in KMF_LITE mode */
1017 size_t kmem_maxverify; /* maximum bytes to inspect in debug routines */
1018 size_t kmem_minfirewall; /* hardware-enforced redzone threshold */
1019
1020 #ifdef _LP64
1021 size_t kmem_max_cached = KMEM_BIG_MAXBUF; /* maximum kmem_alloc cache */
1022 #else
1023 size_t kmem_max_cached = KMEM_BIG_MAXBUF_32BIT; /* maximum kmem_alloc cache */
1024 #endif
1025
1026 #ifdef DEBUG
1027 int kmem_flags = KMF_AUDIT | KMF_DEADBEEF | KMF_REDZONE | KMF_CONTENTS;
1028 #else
1029 int kmem_flags = 0;
1030 #endif
1031 int kmem_ready;
1032
1033 static kmem_cache_t *kmem_slab_cache;
1034 static kmem_cache_t *kmem_bufctl_cache;
1035 static kmem_cache_t *kmem_bufctl_audit_cache;
1036
1037 static kmutex_t kmem_cache_lock; /* inter-cache linkage only */
1038 static list_t kmem_caches;
1039
1040 static taskq_t *kmem_taskq;
1041 static kmutex_t kmem_flags_lock;
1042 static vmem_t *kmem_metadata_arena;
1043 static vmem_t *kmem_msb_arena; /* arena for metadata caches */
1044 static vmem_t *kmem_cache_arena;
1045 static vmem_t *kmem_hash_arena;
1046 static vmem_t *kmem_log_arena;
1047 static vmem_t *kmem_oversize_arena;
1048 static vmem_t *kmem_va_arena;
1049 static vmem_t *kmem_default_arena;
1050 static vmem_t *kmem_firewall_va_arena;
1051 static vmem_t *kmem_firewall_arena;
1052
1053 /*
1054 * kmem slab consolidator thresholds (tunables)
1055 */
1056 size_t kmem_frag_minslabs = 101; /* minimum total slabs */
1057 size_t kmem_frag_numer = 1; /* free buffers (numerator) */
1058 size_t kmem_frag_denom = KMEM_VOID_FRACTION; /* buffers (denominator) */
1059 /*
1060 * Maximum number of slabs from which to move buffers during a single
1061 * maintenance interval while the system is not low on memory.
1062 */
1063 size_t kmem_reclaim_max_slabs = 1;
1064 /*
1065 * Number of slabs to scan backwards from the end of the partial slab list
1066 * when searching for buffers to relocate.
1067 */
1068 size_t kmem_reclaim_scan_range = 12;
1069
1070 /* consolidator knobs */
1071 boolean_t kmem_move_noreap;
1072 boolean_t kmem_move_blocked;
1073 boolean_t kmem_move_fulltilt;
1074 boolean_t kmem_move_any_partial;
1075
1076 #ifdef DEBUG
1077 /*
1078 * kmem consolidator debug tunables:
1079 * Ensure code coverage by occasionally running the consolidator even when the
1080 * caches are not fragmented (they may never be). These intervals are mean time
1081 * in cache maintenance intervals (kmem_cache_update).
1082 */
1083 uint32_t kmem_mtb_move = 60; /* defrag 1 slab (~15min) */
1084 uint32_t kmem_mtb_reap = 1800; /* defrag all slabs (~7.5hrs) */
1085 #endif /* DEBUG */
1086
1087 static kmem_cache_t *kmem_defrag_cache;
1088 static kmem_cache_t *kmem_move_cache;
1089 static taskq_t *kmem_move_taskq;
1090
1091 static void kmem_cache_scan(kmem_cache_t *);
1092 static void kmem_cache_defrag(kmem_cache_t *);
1093 static void kmem_slab_prefill(kmem_cache_t *, kmem_slab_t *);
1094
1095
1096 kmem_log_header_t *kmem_transaction_log;
1097 kmem_log_header_t *kmem_content_log;
1098 kmem_log_header_t *kmem_failure_log;
1099 kmem_log_header_t *kmem_slab_log;
1100
1101 static int kmem_lite_count; /* # of PCs in kmem_buftag_lite_t */
1102
1103 #define KMEM_BUFTAG_LITE_ENTER(bt, count, caller) \
1104 if ((count) > 0) { \
1105 pc_t *_s = ((kmem_buftag_lite_t *)(bt))->bt_history; \
1106 pc_t *_e; \
1107 /* memmove() the old entries down one notch */ \
1108 for (_e = &_s[(count) - 1]; _e > _s; _e--) \
1109 *_e = *(_e - 1); \
1110 *_s = (uintptr_t)(caller); \
1111 }
1112
1113 #define KMERR_MODIFIED 0 /* buffer modified while on freelist */
1114 #define KMERR_REDZONE 1 /* redzone violation (write past end of buf) */
1115 #define KMERR_DUPFREE 2 /* freed a buffer twice */
1116 #define KMERR_BADADDR 3 /* freed a bad (unallocated) address */
1117 #define KMERR_BADBUFTAG 4 /* buftag corrupted */
1118 #define KMERR_BADBUFCTL 5 /* bufctl corrupted */
1119 #define KMERR_BADCACHE 6 /* freed a buffer to the wrong cache */
1120 #define KMERR_BADSIZE 7 /* alloc size != free size */
1121 #define KMERR_BADBASE 8 /* buffer base address wrong */
1122
1123 struct {
1124 hrtime_t kmp_timestamp; /* timestamp of panic */
1125 int kmp_error; /* type of kmem error */
1126 void *kmp_buffer; /* buffer that induced panic */
1127 void *kmp_realbuf; /* real start address for buffer */
1128 kmem_cache_t *kmp_cache; /* buffer's cache according to client */
1129 kmem_cache_t *kmp_realcache; /* actual cache containing buffer */
1130 kmem_slab_t *kmp_slab; /* slab accoring to kmem_findslab() */
1131 kmem_bufctl_t *kmp_bufctl; /* bufctl */
1132 } kmem_panic_info;
1133
1134
1135 static void
1136 copy_pattern(uint64_t pattern, void *buf_arg, size_t size)
1137 {
1138 uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1139 uint64_t *buf = buf_arg;
1140
1141 while (buf < bufend)
1142 *buf++ = pattern;
1143 }
1144
1145 static void *
1146 verify_pattern(uint64_t pattern, void *buf_arg, size_t size)
1147 {
1148 uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1149 uint64_t *buf;
1150
1151 for (buf = buf_arg; buf < bufend; buf++)
1152 if (*buf != pattern)
1153 return (buf);
1154 return (NULL);
1155 }
1156
1157 static void *
1158 verify_and_copy_pattern(uint64_t old, uint64_t new, void *buf_arg, size_t size)
1159 {
1160 uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1161 uint64_t *buf;
1162
1163 for (buf = buf_arg; buf < bufend; buf++) {
1164 if (*buf != old) {
1165 copy_pattern(old, buf_arg,
1166 (char *)buf - (char *)buf_arg);
1167 return (buf);
1168 }
1169 *buf = new;
1170 }
1171
1172 return (NULL);
1173 }
1174
1175 static void
1176 kmem_cache_applyall(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1177 {
1178 kmem_cache_t *cp;
1179
1180 mutex_enter(&kmem_cache_lock);
1181 for (cp = list_head(&kmem_caches); cp != NULL;
1182 cp = list_next(&kmem_caches, cp))
1183 if (tq != NULL)
1184 (void) taskq_dispatch(tq, (task_func_t *)func, cp,
1185 tqflag);
1186 else
1187 func(cp);
1188 mutex_exit(&kmem_cache_lock);
1189 }
1190
1191 static void
1192 kmem_cache_applyall_id(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1193 {
1194 kmem_cache_t *cp;
1195
1196 mutex_enter(&kmem_cache_lock);
1197 for (cp = list_head(&kmem_caches); cp != NULL;
1198 cp = list_next(&kmem_caches, cp)) {
1199 if (!(cp->cache_cflags & KMC_IDENTIFIER))
1200 continue;
1201 if (tq != NULL)
1202 (void) taskq_dispatch(tq, (task_func_t *)func, cp,
1203 tqflag);
1204 else
1205 func(cp);
1206 }
1207 mutex_exit(&kmem_cache_lock);
1208 }
1209
1210 /*
1211 * Debugging support. Given a buffer address, find its slab.
1212 */
1213 static kmem_slab_t *
1214 kmem_findslab(kmem_cache_t *cp, void *buf)
1215 {
1216 kmem_slab_t *sp;
1217
1218 mutex_enter(&cp->cache_lock);
1219 for (sp = list_head(&cp->cache_complete_slabs); sp != NULL;
1220 sp = list_next(&cp->cache_complete_slabs, sp)) {
1221 if (KMEM_SLAB_MEMBER(sp, buf)) {
1222 mutex_exit(&cp->cache_lock);
1223 return (sp);
1224 }
1225 }
1226 for (sp = avl_first(&cp->cache_partial_slabs); sp != NULL;
1227 sp = AVL_NEXT(&cp->cache_partial_slabs, sp)) {
1228 if (KMEM_SLAB_MEMBER(sp, buf)) {
1229 mutex_exit(&cp->cache_lock);
1230 return (sp);
1231 }
1232 }
1233 mutex_exit(&cp->cache_lock);
1234
1235 return (NULL);
1236 }
1237
1238 static void
1239 kmem_error(int error, kmem_cache_t *cparg, void *bufarg)
1240 {
1241 kmem_buftag_t *btp = NULL;
1242 kmem_bufctl_t *bcp = NULL;
1243 kmem_cache_t *cp = cparg;
1244 kmem_slab_t *sp;
1245 uint64_t *off;
1246 void *buf = bufarg;
1247
1248 kmem_logging = 0; /* stop logging when a bad thing happens */
1249
1250 kmem_panic_info.kmp_timestamp = gethrtime();
1251
1252 sp = kmem_findslab(cp, buf);
1253 if (sp == NULL) {
1254 for (cp = list_tail(&kmem_caches); cp != NULL;
1255 cp = list_prev(&kmem_caches, cp)) {
1256 if ((sp = kmem_findslab(cp, buf)) != NULL)
1257 break;
1258 }
1259 }
1260
1261 if (sp == NULL) {
1262 cp = NULL;
1263 error = KMERR_BADADDR;
1264 } else {
1265 if (cp != cparg)
1266 error = KMERR_BADCACHE;
1267 else
1268 buf = (char *)bufarg - ((uintptr_t)bufarg -
1269 (uintptr_t)sp->slab_base) % cp->cache_chunksize;
1270 if (buf != bufarg)
1271 error = KMERR_BADBASE;
1272 if (cp->cache_flags & KMF_BUFTAG)
1273 btp = KMEM_BUFTAG(cp, buf);
1274 if (cp->cache_flags & KMF_HASH) {
1275 mutex_enter(&cp->cache_lock);
1276 for (bcp = *KMEM_HASH(cp, buf); bcp; bcp = bcp->bc_next)
1277 if (bcp->bc_addr == buf)
1278 break;
1279 mutex_exit(&cp->cache_lock);
1280 if (bcp == NULL && btp != NULL)
1281 bcp = btp->bt_bufctl;
1282 if (kmem_findslab(cp->cache_bufctl_cache, bcp) ==
1283 NULL || P2PHASE((uintptr_t)bcp, KMEM_ALIGN) ||
1284 bcp->bc_addr != buf) {
1285 error = KMERR_BADBUFCTL;
1286 bcp = NULL;
1287 }
1288 }
1289 }
1290
1291 kmem_panic_info.kmp_error = error;
1292 kmem_panic_info.kmp_buffer = bufarg;
1293 kmem_panic_info.kmp_realbuf = buf;
1294 kmem_panic_info.kmp_cache = cparg;
1295 kmem_panic_info.kmp_realcache = cp;
1296 kmem_panic_info.kmp_slab = sp;
1297 kmem_panic_info.kmp_bufctl = bcp;
1298
1299 printf("kernel memory allocator: ");
1300
1301 switch (error) {
1302
1303 case KMERR_MODIFIED:
1304 printf("buffer modified after being freed\n");
1305 off = verify_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1306 if (off == NULL) /* shouldn't happen */
1307 off = buf;
1308 printf("modification occurred at offset 0x%lx "
1309 "(0x%llx replaced by 0x%llx)\n",
1310 (uintptr_t)off - (uintptr_t)buf,
1311 (longlong_t)KMEM_FREE_PATTERN, (longlong_t)*off);
1312 break;
1313
1314 case KMERR_REDZONE:
1315 printf("redzone violation: write past end of buffer\n");
1316 break;
1317
1318 case KMERR_BADADDR:
1319 printf("invalid free: buffer not in cache\n");
1320 break;
1321
1322 case KMERR_DUPFREE:
1323 printf("duplicate free: buffer freed twice\n");
1324 break;
1325
1326 case KMERR_BADBUFTAG:
1327 printf("boundary tag corrupted\n");
1328 printf("bcp ^ bxstat = %lx, should be %lx\n",
1329 (intptr_t)btp->bt_bufctl ^ btp->bt_bxstat,
1330 KMEM_BUFTAG_FREE);
1331 break;
1332
1333 case KMERR_BADBUFCTL:
1334 printf("bufctl corrupted\n");
1335 break;
1336
1337 case KMERR_BADCACHE:
1338 printf("buffer freed to wrong cache\n");
1339 printf("buffer was allocated from %s,\n", cp->cache_name);
1340 printf("caller attempting free to %s.\n", cparg->cache_name);
1341 break;
1342
1343 case KMERR_BADSIZE:
1344 printf("bad free: free size (%u) != alloc size (%u)\n",
1345 KMEM_SIZE_DECODE(((uint32_t *)btp)[0]),
1346 KMEM_SIZE_DECODE(((uint32_t *)btp)[1]));
1347 break;
1348
1349 case KMERR_BADBASE:
1350 printf("bad free: free address (%p) != alloc address (%p)\n",
1351 bufarg, buf);
1352 break;
1353 }
1354
1355 printf("buffer=%p bufctl=%p cache: %s\n",
1356 bufarg, (void *)bcp, cparg->cache_name);
1357
1358 if (bcp != NULL && (cp->cache_flags & KMF_AUDIT) &&
1359 error != KMERR_BADBUFCTL) {
1360 int d;
1361 timestruc_t ts;
1362 kmem_bufctl_audit_t *bcap = (kmem_bufctl_audit_t *)bcp;
1363
1364 hrt2ts(kmem_panic_info.kmp_timestamp - bcap->bc_timestamp, &ts);
1365 printf("previous transaction on buffer %p:\n", buf);
1366 printf("thread=%p time=T-%ld.%09ld slab=%p cache: %s\n",
1367 (void *)bcap->bc_thread, ts.tv_sec, ts.tv_nsec,
1368 (void *)sp, cp->cache_name);
1369 for (d = 0; d < MIN(bcap->bc_depth, KMEM_STACK_DEPTH); d++) {
1370 ulong_t off;
1371 char *sym = kobj_getsymname(bcap->bc_stack[d], &off);
1372 printf("%s+%lx\n", sym ? sym : "?", off);
1373 }
1374 }
1375 if (kmem_panic > 0)
1376 panic("kernel heap corruption detected");
1377 if (kmem_panic == 0)
1378 debug_enter(NULL);
1379 kmem_logging = 1; /* resume logging */
1380 }
1381
1382 static kmem_log_header_t *
1383 kmem_log_init(size_t logsize)
1384 {
1385 kmem_log_header_t *lhp;
1386 int nchunks = 4 * max_ncpus;
1387 size_t lhsize = (size_t)&((kmem_log_header_t *)0)->lh_cpu[max_ncpus];
1388 int i;
1389
1390 /*
1391 * Make sure that lhp->lh_cpu[] is nicely aligned
1392 * to prevent false sharing of cache lines.
1393 */
1394 lhsize = P2ROUNDUP(lhsize, KMEM_ALIGN);
1395 lhp = vmem_xalloc(kmem_log_arena, lhsize, 64, P2NPHASE(lhsize, 64), 0,
1396 NULL, NULL, VM_SLEEP);
1397 bzero(lhp, lhsize);
1398
1399 mutex_init(&lhp->lh_lock, NULL, MUTEX_DEFAULT, NULL);
1400 lhp->lh_nchunks = nchunks;
1401 lhp->lh_chunksize = P2ROUNDUP(logsize / nchunks + 1, PAGESIZE);
1402 lhp->lh_base = vmem_alloc(kmem_log_arena,
1403 lhp->lh_chunksize * nchunks, VM_SLEEP);
1404 lhp->lh_free = vmem_alloc(kmem_log_arena,
1405 nchunks * sizeof (int), VM_SLEEP);
1406 bzero(lhp->lh_base, lhp->lh_chunksize * nchunks);
1407
1408 for (i = 0; i < max_ncpus; i++) {
1409 kmem_cpu_log_header_t *clhp = &lhp->lh_cpu[i];
1410 mutex_init(&clhp->clh_lock, NULL, MUTEX_DEFAULT, NULL);
1411 clhp->clh_chunk = i;
1412 }
1413
1414 for (i = max_ncpus; i < nchunks; i++)
1415 lhp->lh_free[i] = i;
1416
1417 lhp->lh_head = max_ncpus;
1418 lhp->lh_tail = 0;
1419
1420 return (lhp);
1421 }
1422
1423 static void *
1424 kmem_log_enter(kmem_log_header_t *lhp, void *data, size_t size)
1425 {
1426 void *logspace;
1427 kmem_cpu_log_header_t *clhp = &lhp->lh_cpu[CPU->cpu_seqid];
1428
1429 if (lhp == NULL || kmem_logging == 0 || panicstr)
1430 return (NULL);
1431
1432 mutex_enter(&clhp->clh_lock);
1433 clhp->clh_hits++;
1434 if (size > clhp->clh_avail) {
1435 mutex_enter(&lhp->lh_lock);
1436 lhp->lh_hits++;
1437 lhp->lh_free[lhp->lh_tail] = clhp->clh_chunk;
1438 lhp->lh_tail = (lhp->lh_tail + 1) % lhp->lh_nchunks;
1439 clhp->clh_chunk = lhp->lh_free[lhp->lh_head];
1440 lhp->lh_head = (lhp->lh_head + 1) % lhp->lh_nchunks;
1441 clhp->clh_current = lhp->lh_base +
1442 clhp->clh_chunk * lhp->lh_chunksize;
1443 clhp->clh_avail = lhp->lh_chunksize;
1444 if (size > lhp->lh_chunksize)
1445 size = lhp->lh_chunksize;
1446 mutex_exit(&lhp->lh_lock);
1447 }
1448 logspace = clhp->clh_current;
1449 clhp->clh_current += size;
1450 clhp->clh_avail -= size;
1451 bcopy(data, logspace, size);
1452 mutex_exit(&clhp->clh_lock);
1453 return (logspace);
1454 }
1455
1456 #define KMEM_AUDIT(lp, cp, bcp) \
1457 { \
1458 kmem_bufctl_audit_t *_bcp = (kmem_bufctl_audit_t *)(bcp); \
1459 _bcp->bc_timestamp = gethrtime(); \
1460 _bcp->bc_thread = curthread; \
1461 _bcp->bc_depth = getpcstack(_bcp->bc_stack, KMEM_STACK_DEPTH); \
1462 _bcp->bc_lastlog = kmem_log_enter((lp), _bcp, sizeof (*_bcp)); \
1463 }
1464
1465 static void
1466 kmem_log_event(kmem_log_header_t *lp, kmem_cache_t *cp,
1467 kmem_slab_t *sp, void *addr)
1468 {
1469 kmem_bufctl_audit_t bca;
1470
1471 bzero(&bca, sizeof (kmem_bufctl_audit_t));
1472 bca.bc_addr = addr;
1473 bca.bc_slab = sp;
1474 bca.bc_cache = cp;
1475 KMEM_AUDIT(lp, cp, &bca);
1476 }
1477
1478 /*
1479 * Create a new slab for cache cp.
1480 */
1481 static kmem_slab_t *
1482 kmem_slab_create(kmem_cache_t *cp, int kmflag)
1483 {
1484 size_t slabsize = cp->cache_slabsize;
1485 size_t chunksize = cp->cache_chunksize;
1486 int cache_flags = cp->cache_flags;
1487 size_t color, chunks;
1488 char *buf, *slab;
1489 kmem_slab_t *sp;
1490 kmem_bufctl_t *bcp;
1491 vmem_t *vmp = cp->cache_arena;
1492
1493 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1494
1495 color = cp->cache_color + cp->cache_align;
1496 if (color > cp->cache_maxcolor)
1497 color = cp->cache_mincolor;
1498 cp->cache_color = color;
1499
1500 slab = vmem_alloc(vmp, slabsize, kmflag & KM_VMFLAGS);
1501
1502 if (slab == NULL)
1503 goto vmem_alloc_failure;
1504
1505 ASSERT(P2PHASE((uintptr_t)slab, vmp->vm_quantum) == 0);
1506
1507 /*
1508 * Reverify what was already checked in kmem_cache_set_move(), since the
1509 * consolidator depends (for correctness) on slabs being initialized
1510 * with the 0xbaddcafe memory pattern (setting a low order bit usable by
1511 * clients to distinguish uninitialized memory from known objects).
1512 */
1513 ASSERT((cp->cache_move == NULL) || !(cp->cache_cflags & KMC_NOTOUCH));
1514 if (!(cp->cache_cflags & KMC_NOTOUCH))
1515 copy_pattern(KMEM_UNINITIALIZED_PATTERN, slab, slabsize);
1516
1517 if (cache_flags & KMF_HASH) {
1518 if ((sp = kmem_cache_alloc(kmem_slab_cache, kmflag)) == NULL)
1519 goto slab_alloc_failure;
1520 chunks = (slabsize - color) / chunksize;
1521 } else {
1522 sp = KMEM_SLAB(cp, slab);
1523 chunks = (slabsize - sizeof (kmem_slab_t) - color) / chunksize;
1524 }
1525
1526 sp->slab_cache = cp;
1527 sp->slab_head = NULL;
1528 sp->slab_refcnt = 0;
1529 sp->slab_base = buf = slab + color;
1530 sp->slab_chunks = chunks;
1531 sp->slab_stuck_offset = (uint32_t)-1;
1532 sp->slab_later_count = 0;
1533 sp->slab_flags = 0;
1534
1535 ASSERT(chunks > 0);
1536 while (chunks-- != 0) {
1537 if (cache_flags & KMF_HASH) {
1538 bcp = kmem_cache_alloc(cp->cache_bufctl_cache, kmflag);
1539 if (bcp == NULL)
1540 goto bufctl_alloc_failure;
1541 if (cache_flags & KMF_AUDIT) {
1542 kmem_bufctl_audit_t *bcap =
1543 (kmem_bufctl_audit_t *)bcp;
1544 bzero(bcap, sizeof (kmem_bufctl_audit_t));
1545 bcap->bc_cache = cp;
1546 }
1547 bcp->bc_addr = buf;
1548 bcp->bc_slab = sp;
1549 } else {
1550 bcp = KMEM_BUFCTL(cp, buf);
1551 }
1552 if (cache_flags & KMF_BUFTAG) {
1553 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1554 btp->bt_redzone = KMEM_REDZONE_PATTERN;
1555 btp->bt_bufctl = bcp;
1556 btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1557 if (cache_flags & KMF_DEADBEEF) {
1558 copy_pattern(KMEM_FREE_PATTERN, buf,
1559 cp->cache_verify);
1560 }
1561 }
1562 bcp->bc_next = sp->slab_head;
1563 sp->slab_head = bcp;
1564 buf += chunksize;
1565 }
1566
1567 kmem_log_event(kmem_slab_log, cp, sp, slab);
1568
1569 return (sp);
1570
1571 bufctl_alloc_failure:
1572
1573 while ((bcp = sp->slab_head) != NULL) {
1574 sp->slab_head = bcp->bc_next;
1575 kmem_cache_free(cp->cache_bufctl_cache, bcp);
1576 }
1577 kmem_cache_free(kmem_slab_cache, sp);
1578
1579 slab_alloc_failure:
1580
1581 vmem_free(vmp, slab, slabsize);
1582
1583 vmem_alloc_failure:
1584
1585 kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1586 atomic_inc_64(&cp->cache_alloc_fail);
1587
1588 return (NULL);
1589 }
1590
1591 /*
1592 * Destroy a slab.
1593 */
1594 static void
1595 kmem_slab_destroy(kmem_cache_t *cp, kmem_slab_t *sp)
1596 {
1597 vmem_t *vmp = cp->cache_arena;
1598 void *slab = (void *)P2ALIGN((uintptr_t)sp->slab_base, vmp->vm_quantum);
1599
1600 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1601 ASSERT(sp->slab_refcnt == 0);
1602
1603 if (cp->cache_flags & KMF_HASH) {
1604 kmem_bufctl_t *bcp;
1605 while ((bcp = sp->slab_head) != NULL) {
1606 sp->slab_head = bcp->bc_next;
1607 kmem_cache_free(cp->cache_bufctl_cache, bcp);
1608 }
1609 kmem_cache_free(kmem_slab_cache, sp);
1610 }
1611 vmem_free(vmp, slab, cp->cache_slabsize);
1612 }
1613
1614 static void *
1615 kmem_slab_alloc_impl(kmem_cache_t *cp, kmem_slab_t *sp, boolean_t prefill)
1616 {
1617 kmem_bufctl_t *bcp, **hash_bucket;
1618 void *buf;
1619 boolean_t new_slab = (sp->slab_refcnt == 0);
1620
1621 ASSERT(MUTEX_HELD(&cp->cache_lock));
1622 /*
1623 * kmem_slab_alloc() drops cache_lock when it creates a new slab, so we
1624 * can't ASSERT(avl_is_empty(&cp->cache_partial_slabs)) here when the
1625 * slab is newly created.
1626 */
1627 ASSERT(new_slab || (KMEM_SLAB_IS_PARTIAL(sp) &&
1628 (sp == avl_first(&cp->cache_partial_slabs))));
1629 ASSERT(sp->slab_cache == cp);
1630
1631 cp->cache_slab_alloc++;
1632 cp->cache_bufslab--;
1633 sp->slab_refcnt++;
1634
1635 bcp = sp->slab_head;
1636 sp->slab_head = bcp->bc_next;
1637
1638 if (cp->cache_flags & KMF_HASH) {
1639 /*
1640 * Add buffer to allocated-address hash table.
1641 */
1642 buf = bcp->bc_addr;
1643 hash_bucket = KMEM_HASH(cp, buf);
1644 bcp->bc_next = *hash_bucket;
1645 *hash_bucket = bcp;
1646 if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1647 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1648 }
1649 } else {
1650 buf = KMEM_BUF(cp, bcp);
1651 }
1652
1653 ASSERT(KMEM_SLAB_MEMBER(sp, buf));
1654
1655 if (sp->slab_head == NULL) {
1656 ASSERT(KMEM_SLAB_IS_ALL_USED(sp));
1657 if (new_slab) {
1658 ASSERT(sp->slab_chunks == 1);
1659 } else {
1660 ASSERT(sp->slab_chunks > 1); /* the slab was partial */
1661 avl_remove(&cp->cache_partial_slabs, sp);
1662 sp->slab_later_count = 0; /* clear history */
1663 sp->slab_flags &= ~KMEM_SLAB_NOMOVE;
1664 sp->slab_stuck_offset = (uint32_t)-1;
1665 }
1666 list_insert_head(&cp->cache_complete_slabs, sp);
1667 cp->cache_complete_slab_count++;
1668 return (buf);
1669 }
1670
1671 ASSERT(KMEM_SLAB_IS_PARTIAL(sp));
1672 /*
1673 * Peek to see if the magazine layer is enabled before
1674 * we prefill. We're not holding the cpu cache lock,
1675 * so the peek could be wrong, but there's no harm in it.
1676 */
1677 if (new_slab && prefill && (cp->cache_flags & KMF_PREFILL) &&
1678 (KMEM_CPU_CACHE(cp)->cc_magsize != 0)) {
1679 kmem_slab_prefill(cp, sp);
1680 return (buf);
1681 }
1682
1683 if (new_slab) {
1684 avl_add(&cp->cache_partial_slabs, sp);
1685 return (buf);
1686 }
1687
1688 /*
1689 * The slab is now more allocated than it was, so the
1690 * order remains unchanged.
1691 */
1692 ASSERT(!avl_update(&cp->cache_partial_slabs, sp));
1693 return (buf);
1694 }
1695
1696 /*
1697 * Allocate a raw (unconstructed) buffer from cp's slab layer.
1698 */
1699 static void *
1700 kmem_slab_alloc(kmem_cache_t *cp, int kmflag)
1701 {
1702 kmem_slab_t *sp;
1703 void *buf;
1704 boolean_t test_destructor;
1705
1706 mutex_enter(&cp->cache_lock);
1707 test_destructor = (cp->cache_slab_alloc == 0);
1708 sp = avl_first(&cp->cache_partial_slabs);
1709 if (sp == NULL) {
1710 ASSERT(cp->cache_bufslab == 0);
1711
1712 /*
1713 * The freelist is empty. Create a new slab.
1714 */
1715 mutex_exit(&cp->cache_lock);
1716 if ((sp = kmem_slab_create(cp, kmflag)) == NULL) {
1717 return (NULL);
1718 }
1719 mutex_enter(&cp->cache_lock);
1720 cp->cache_slab_create++;
1721 if ((cp->cache_buftotal += sp->slab_chunks) > cp->cache_bufmax)
1722 cp->cache_bufmax = cp->cache_buftotal;
1723 cp->cache_bufslab += sp->slab_chunks;
1724 }
1725
1726 buf = kmem_slab_alloc_impl(cp, sp, B_TRUE);
1727 ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1728 (cp->cache_complete_slab_count +
1729 avl_numnodes(&cp->cache_partial_slabs) +
1730 (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1731 mutex_exit(&cp->cache_lock);
1732
1733 if (test_destructor && cp->cache_destructor != NULL) {
1734 /*
1735 * On the first kmem_slab_alloc(), assert that it is valid to
1736 * call the destructor on a newly constructed object without any
1737 * client involvement.
1738 */
1739 if ((cp->cache_constructor == NULL) ||
1740 cp->cache_constructor(buf, cp->cache_private,
1741 kmflag) == 0) {
1742 cp->cache_destructor(buf, cp->cache_private);
1743 }
1744 copy_pattern(KMEM_UNINITIALIZED_PATTERN, buf,
1745 cp->cache_bufsize);
1746 if (cp->cache_flags & KMF_DEADBEEF) {
1747 copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1748 }
1749 }
1750
1751 return (buf);
1752 }
1753
1754 static void kmem_slab_move_yes(kmem_cache_t *, kmem_slab_t *, void *);
1755
1756 /*
1757 * Free a raw (unconstructed) buffer to cp's slab layer.
1758 */
1759 static void
1760 kmem_slab_free(kmem_cache_t *cp, void *buf)
1761 {
1762 kmem_slab_t *sp;
1763 kmem_bufctl_t *bcp, **prev_bcpp;
1764
1765 ASSERT(buf != NULL);
1766
1767 mutex_enter(&cp->cache_lock);
1768 cp->cache_slab_free++;
1769
1770 if (cp->cache_flags & KMF_HASH) {
1771 /*
1772 * Look up buffer in allocated-address hash table.
1773 */
1774 prev_bcpp = KMEM_HASH(cp, buf);
1775 while ((bcp = *prev_bcpp) != NULL) {
1776 if (bcp->bc_addr == buf) {
1777 *prev_bcpp = bcp->bc_next;
1778 sp = bcp->bc_slab;
1779 break;
1780 }
1781 cp->cache_lookup_depth++;
1782 prev_bcpp = &bcp->bc_next;
1783 }
1784 } else {
1785 bcp = KMEM_BUFCTL(cp, buf);
1786 sp = KMEM_SLAB(cp, buf);
1787 }
1788
1789 if (bcp == NULL || sp->slab_cache != cp || !KMEM_SLAB_MEMBER(sp, buf)) {
1790 mutex_exit(&cp->cache_lock);
1791 kmem_error(KMERR_BADADDR, cp, buf);
1792 return;
1793 }
1794
1795 if (KMEM_SLAB_OFFSET(sp, buf) == sp->slab_stuck_offset) {
1796 /*
1797 * If this is the buffer that prevented the consolidator from
1798 * clearing the slab, we can reset the slab flags now that the
1799 * buffer is freed. (It makes sense to do this in
1800 * kmem_cache_free(), where the client gives up ownership of the
1801 * buffer, but on the hot path the test is too expensive.)
1802 */
1803 kmem_slab_move_yes(cp, sp, buf);
1804 }
1805
1806 if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1807 if (cp->cache_flags & KMF_CONTENTS)
1808 ((kmem_bufctl_audit_t *)bcp)->bc_contents =
1809 kmem_log_enter(kmem_content_log, buf,
1810 cp->cache_contents);
1811 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1812 }
1813
1814 bcp->bc_next = sp->slab_head;
1815 sp->slab_head = bcp;
1816
1817 cp->cache_bufslab++;
1818 ASSERT(sp->slab_refcnt >= 1);
1819
1820 if (--sp->slab_refcnt == 0) {
1821 /*
1822 * There are no outstanding allocations from this slab,
1823 * so we can reclaim the memory.
1824 */
1825 if (sp->slab_chunks == 1) {
1826 list_remove(&cp->cache_complete_slabs, sp);
1827 cp->cache_complete_slab_count--;
1828 } else {
1829 avl_remove(&cp->cache_partial_slabs, sp);
1830 }
1831
1832 cp->cache_buftotal -= sp->slab_chunks;
1833 cp->cache_bufslab -= sp->slab_chunks;
1834 /*
1835 * Defer releasing the slab to the virtual memory subsystem
1836 * while there is a pending move callback, since we guarantee
1837 * that buffers passed to the move callback have only been
1838 * touched by kmem or by the client itself. Since the memory
1839 * patterns baddcafe (uninitialized) and deadbeef (freed) both
1840 * set at least one of the two lowest order bits, the client can
1841 * test those bits in the move callback to determine whether or
1842 * not it knows about the buffer (assuming that the client also
1843 * sets one of those low order bits whenever it frees a buffer).
1844 */
1845 if (cp->cache_defrag == NULL ||
1846 (avl_is_empty(&cp->cache_defrag->kmd_moves_pending) &&
1847 !(sp->slab_flags & KMEM_SLAB_MOVE_PENDING))) {
1848 cp->cache_slab_destroy++;
1849 mutex_exit(&cp->cache_lock);
1850 kmem_slab_destroy(cp, sp);
1851 } else {
1852 list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
1853 /*
1854 * Slabs are inserted at both ends of the deadlist to
1855 * distinguish between slabs freed while move callbacks
1856 * are pending (list head) and a slab freed while the
1857 * lock is dropped in kmem_move_buffers() (list tail) so
1858 * that in both cases slab_destroy() is called from the
1859 * right context.
1860 */
1861 if (sp->slab_flags & KMEM_SLAB_MOVE_PENDING) {
1862 list_insert_tail(deadlist, sp);
1863 } else {
1864 list_insert_head(deadlist, sp);
1865 }
1866 cp->cache_defrag->kmd_deadcount++;
1867 mutex_exit(&cp->cache_lock);
1868 }
1869 return;
1870 }
1871
1872 if (bcp->bc_next == NULL) {
1873 /* Transition the slab from completely allocated to partial. */
1874 ASSERT(sp->slab_refcnt == (sp->slab_chunks - 1));
1875 ASSERT(sp->slab_chunks > 1);
1876 list_remove(&cp->cache_complete_slabs, sp);
1877 cp->cache_complete_slab_count--;
1878 avl_add(&cp->cache_partial_slabs, sp);
1879 } else {
1880 (void) avl_update_gt(&cp->cache_partial_slabs, sp);
1881 }
1882
1883 ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1884 (cp->cache_complete_slab_count +
1885 avl_numnodes(&cp->cache_partial_slabs) +
1886 (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1887 mutex_exit(&cp->cache_lock);
1888 }
1889
1890 /*
1891 * Return -1 if kmem_error, 1 if constructor fails, 0 if successful.
1892 */
1893 static int
1894 kmem_cache_alloc_debug(kmem_cache_t *cp, void *buf, int kmflag, int construct,
1895 caddr_t caller)
1896 {
1897 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1898 kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
1899 uint32_t mtbf;
1900
1901 if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
1902 kmem_error(KMERR_BADBUFTAG, cp, buf);
1903 return (-1);
1904 }
1905
1906 btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_ALLOC;
1907
1908 if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
1909 kmem_error(KMERR_BADBUFCTL, cp, buf);
1910 return (-1);
1911 }
1912
1913 if (cp->cache_flags & KMF_DEADBEEF) {
1914 if (!construct && (cp->cache_flags & KMF_LITE)) {
1915 if (*(uint64_t *)buf != KMEM_FREE_PATTERN) {
1916 kmem_error(KMERR_MODIFIED, cp, buf);
1917 return (-1);
1918 }
1919 if (cp->cache_constructor != NULL)
1920 *(uint64_t *)buf = btp->bt_redzone;
1921 else
1922 *(uint64_t *)buf = KMEM_UNINITIALIZED_PATTERN;
1923 } else {
1924 construct = 1;
1925 if (verify_and_copy_pattern(KMEM_FREE_PATTERN,
1926 KMEM_UNINITIALIZED_PATTERN, buf,
1927 cp->cache_verify)) {
1928 kmem_error(KMERR_MODIFIED, cp, buf);
1929 return (-1);
1930 }
1931 }
1932 }
1933 btp->bt_redzone = KMEM_REDZONE_PATTERN;
1934
1935 if ((mtbf = kmem_mtbf | cp->cache_mtbf) != 0 &&
1936 gethrtime() % mtbf == 0 &&
1937 (kmflag & (KM_NOSLEEP | KM_PANIC)) == KM_NOSLEEP) {
1938 kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1939 if (!construct && cp->cache_destructor != NULL)
1940 cp->cache_destructor(buf, cp->cache_private);
1941 } else {
1942 mtbf = 0;
1943 }
1944
1945 if (mtbf || (construct && cp->cache_constructor != NULL &&
1946 cp->cache_constructor(buf, cp->cache_private, kmflag) != 0)) {
1947 atomic_inc_64(&cp->cache_alloc_fail);
1948 btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1949 if (cp->cache_flags & KMF_DEADBEEF)
1950 copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1951 kmem_slab_free(cp, buf);
1952 return (1);
1953 }
1954
1955 if (cp->cache_flags & KMF_AUDIT) {
1956 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1957 }
1958
1959 if ((cp->cache_flags & KMF_LITE) &&
1960 !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
1961 KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
1962 }
1963
1964 return (0);
1965 }
1966
1967 static int
1968 kmem_cache_free_debug(kmem_cache_t *cp, void *buf, caddr_t caller)
1969 {
1970 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1971 kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
1972 kmem_slab_t *sp;
1973
1974 if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_ALLOC)) {
1975 if (btp->bt_bxstat == ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
1976 kmem_error(KMERR_DUPFREE, cp, buf);
1977 return (-1);
1978 }
1979 sp = kmem_findslab(cp, buf);
1980 if (sp == NULL || sp->slab_cache != cp)
1981 kmem_error(KMERR_BADADDR, cp, buf);
1982 else
1983 kmem_error(KMERR_REDZONE, cp, buf);
1984 return (-1);
1985 }
1986
1987 btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1988
1989 if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
1990 kmem_error(KMERR_BADBUFCTL, cp, buf);
1991 return (-1);
1992 }
1993
1994 if (btp->bt_redzone != KMEM_REDZONE_PATTERN) {
1995 kmem_error(KMERR_REDZONE, cp, buf);
1996 return (-1);
1997 }
1998
1999 if (cp->cache_flags & KMF_AUDIT) {
2000 if (cp->cache_flags & KMF_CONTENTS)
2001 bcp->bc_contents = kmem_log_enter(kmem_content_log,
2002 buf, cp->cache_contents);
2003 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
2004 }
2005
2006 if ((cp->cache_flags & KMF_LITE) &&
2007 !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
2008 KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
2009 }
2010
2011 if (cp->cache_flags & KMF_DEADBEEF) {
2012 if (cp->cache_flags & KMF_LITE)
2013 btp->bt_redzone = *(uint64_t *)buf;
2014 else if (cp->cache_destructor != NULL)
2015 cp->cache_destructor(buf, cp->cache_private);
2016
2017 copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
2018 }
2019
2020 return (0);
2021 }
2022
2023 /*
2024 * Free each object in magazine mp to cp's slab layer, and free mp itself.
2025 */
2026 static void
2027 kmem_magazine_destroy(kmem_cache_t *cp, kmem_magazine_t *mp, int nrounds)
2028 {
2029 int round;
2030
2031 ASSERT(!list_link_active(&cp->cache_link) ||
2032 taskq_member(kmem_taskq, curthread));
2033
2034 for (round = 0; round < nrounds; round++) {
2035 void *buf = mp->mag_round[round];
2036
2037 if (cp->cache_flags & KMF_DEADBEEF) {
2038 if (verify_pattern(KMEM_FREE_PATTERN, buf,
2039 cp->cache_verify) != NULL) {
2040 kmem_error(KMERR_MODIFIED, cp, buf);
2041 continue;
2042 }
2043 if ((cp->cache_flags & KMF_LITE) &&
2044 cp->cache_destructor != NULL) {
2045 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2046 *(uint64_t *)buf = btp->bt_redzone;
2047 cp->cache_destructor(buf, cp->cache_private);
2048 *(uint64_t *)buf = KMEM_FREE_PATTERN;
2049 }
2050 } else if (cp->cache_destructor != NULL) {
2051 cp->cache_destructor(buf, cp->cache_private);
2052 }
2053
2054 kmem_slab_free(cp, buf);
2055 }
2056 ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2057 kmem_cache_free(cp->cache_magtype->mt_cache, mp);
2058 }
2059
2060 /*
2061 * Allocate a magazine from the depot.
2062 */
2063 static kmem_magazine_t *
2064 kmem_depot_alloc(kmem_cache_t *cp, kmem_maglist_t *mlp)
2065 {
2066 kmem_magazine_t *mp;
2067
2068 /*
2069 * If we can't get the depot lock without contention,
2070 * update our contention count. We use the depot
2071 * contention rate to determine whether we need to
2072 * increase the magazine size for better scalability.
2073 */
2074 if (!mutex_tryenter(&cp->cache_depot_lock)) {
2075 mutex_enter(&cp->cache_depot_lock);
2076 cp->cache_depot_contention++;
2077 }
2078
2079 if ((mp = mlp->ml_list) != NULL) {
2080 ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2081 mlp->ml_list = mp->mag_next;
2082 if (--mlp->ml_total < mlp->ml_min)
2083 mlp->ml_min = mlp->ml_total;
2084 mlp->ml_alloc++;
2085 }
2086
2087 mutex_exit(&cp->cache_depot_lock);
2088
2089 return (mp);
2090 }
2091
2092 /*
2093 * Free a magazine to the depot.
2094 */
2095 static void
2096 kmem_depot_free(kmem_cache_t *cp, kmem_maglist_t *mlp, kmem_magazine_t *mp)
2097 {
2098 mutex_enter(&cp->cache_depot_lock);
2099 ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2100 mp->mag_next = mlp->ml_list;
2101 mlp->ml_list = mp;
2102 mlp->ml_total++;
2103 mutex_exit(&cp->cache_depot_lock);
2104 }
2105
2106 /*
2107 * Update the working set statistics for cp's depot.
2108 */
2109 static void
2110 kmem_depot_ws_update(kmem_cache_t *cp)
2111 {
2112 mutex_enter(&cp->cache_depot_lock);
2113 cp->cache_full.ml_reaplimit = cp->cache_full.ml_min;
2114 cp->cache_full.ml_min = cp->cache_full.ml_total;
2115 cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_min;
2116 cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2117 mutex_exit(&cp->cache_depot_lock);
2118 }
2119
2120 /*
2121 * Set the working set statistics for cp's depot to zero. (Everything is
2122 * eligible for reaping.)
2123 */
2124 static void
2125 kmem_depot_ws_zero(kmem_cache_t *cp)
2126 {
2127 mutex_enter(&cp->cache_depot_lock);
2128 cp->cache_full.ml_reaplimit = cp->cache_full.ml_total;
2129 cp->cache_full.ml_min = cp->cache_full.ml_total;
2130 cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_total;
2131 cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2132 mutex_exit(&cp->cache_depot_lock);
2133 }
2134
2135 /*
2136 * The number of bytes to reap before we call kpreempt(). The default (1MB)
2137 * causes us to preempt reaping up to hundreds of times per second. Using a
2138 * larger value (1GB) causes this to have virtually no effect.
2139 */
2140 size_t kmem_reap_preempt_bytes = 1024 * 1024;
2141
2142 /*
2143 * Reap all magazines that have fallen out of the depot's working set.
2144 */
2145 static void
2146 kmem_depot_ws_reap(kmem_cache_t *cp)
2147 {
2148 size_t bytes = 0;
2149 long reap;
2150 kmem_magazine_t *mp;
2151
2152 ASSERT(!list_link_active(&cp->cache_link) ||
2153 taskq_member(kmem_taskq, curthread));
2154
2155 reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
2156 while (reap-- &&
2157 (mp = kmem_depot_alloc(cp, &cp->cache_full)) != NULL) {
2158 kmem_magazine_destroy(cp, mp, cp->cache_magtype->mt_magsize);
2159 bytes += cp->cache_magtype->mt_magsize * cp->cache_bufsize;
2160 if (bytes > kmem_reap_preempt_bytes) {
2161 kpreempt(KPREEMPT_SYNC);
2162 bytes = 0;
2163 }
2164 }
2165
2166 reap = MIN(cp->cache_empty.ml_reaplimit, cp->cache_empty.ml_min);
2167 while (reap-- &&
2168 (mp = kmem_depot_alloc(cp, &cp->cache_empty)) != NULL) {
2169 kmem_magazine_destroy(cp, mp, 0);
2170 bytes += cp->cache_magtype->mt_magsize * cp->cache_bufsize;
2171 if (bytes > kmem_reap_preempt_bytes) {
2172 kpreempt(KPREEMPT_SYNC);
2173 bytes = 0;
2174 }
2175 }
2176 }
2177
2178 static void
2179 kmem_cpu_reload(kmem_cpu_cache_t *ccp, kmem_magazine_t *mp, int rounds)
2180 {
2181 ASSERT((ccp->cc_loaded == NULL && ccp->cc_rounds == -1) ||
2182 (ccp->cc_loaded && ccp->cc_rounds + rounds == ccp->cc_magsize));
2183 ASSERT(ccp->cc_magsize > 0);
2184
2185 ccp->cc_ploaded = ccp->cc_loaded;
2186 ccp->cc_prounds = ccp->cc_rounds;
2187 ccp->cc_loaded = mp;
2188 ccp->cc_rounds = rounds;
2189 }
2190
2191 /*
2192 * Intercept kmem alloc/free calls during crash dump in order to avoid
2193 * changing kmem state while memory is being saved to the dump device.
2194 * Otherwise, ::kmem_verify will report "corrupt buffers". Note that
2195 * there are no locks because only one CPU calls kmem during a crash
2196 * dump. To enable this feature, first create the associated vmem
2197 * arena with VMC_DUMPSAFE.
2198 */
2199 static void *kmem_dump_start; /* start of pre-reserved heap */
2200 static void *kmem_dump_end; /* end of heap area */
2201 static void *kmem_dump_curr; /* current free heap pointer */
2202 static size_t kmem_dump_size; /* size of heap area */
2203
2204 /* append to each buf created in the pre-reserved heap */
2205 typedef struct kmem_dumpctl {
2206 void *kdc_next; /* cache dump free list linkage */
2207 } kmem_dumpctl_t;
2208
2209 #define KMEM_DUMPCTL(cp, buf) \
2210 ((kmem_dumpctl_t *)P2ROUNDUP((uintptr_t)(buf) + (cp)->cache_bufsize, \
2211 sizeof (void *)))
2212
2213 /* Keep some simple stats. */
2214 #define KMEM_DUMP_LOGS (100)
2215
2216 typedef struct kmem_dump_log {
2217 kmem_cache_t *kdl_cache;
2218 uint_t kdl_allocs; /* # of dump allocations */
2219 uint_t kdl_frees; /* # of dump frees */
2220 uint_t kdl_alloc_fails; /* # of allocation failures */
2221 uint_t kdl_free_nondump; /* # of non-dump frees */
2222 uint_t kdl_unsafe; /* cache was used, but unsafe */
2223 } kmem_dump_log_t;
2224
2225 static kmem_dump_log_t *kmem_dump_log;
2226 static int kmem_dump_log_idx;
2227
2228 #define KDI_LOG(cp, stat) { \
2229 kmem_dump_log_t *kdl; \
2230 if ((kdl = (kmem_dump_log_t *)((cp)->cache_dumplog)) != NULL) { \
2231 kdl->stat++; \
2232 } else if (kmem_dump_log_idx < KMEM_DUMP_LOGS) { \
2233 kdl = &kmem_dump_log[kmem_dump_log_idx++]; \
2234 kdl->stat++; \
2235 kdl->kdl_cache = (cp); \
2236 (cp)->cache_dumplog = kdl; \
2237 } \
2238 }
2239
2240 /* set non zero for full report */
2241 uint_t kmem_dump_verbose = 0;
2242
2243 /* stats for overize heap */
2244 uint_t kmem_dump_oversize_allocs = 0;
2245 uint_t kmem_dump_oversize_max = 0;
2246
2247 static void
2248 kmem_dumppr(char **pp, char *e, const char *format, ...)
2249 {
2250 char *p = *pp;
2251
2252 if (p < e) {
2253 int n;
2254 va_list ap;
2255
2256 va_start(ap, format);
2257 n = vsnprintf(p, e - p, format, ap);
2258 va_end(ap);
2259 *pp = p + n;
2260 }
2261 }
2262
2263 /*
2264 * Called when dumpadm(1M) configures dump parameters.
2265 */
2266 void
2267 kmem_dump_init(size_t size)
2268 {
2269 if (kmem_dump_start != NULL)
2270 kmem_free(kmem_dump_start, kmem_dump_size);
2271
2272 if (kmem_dump_log == NULL)
2273 kmem_dump_log = (kmem_dump_log_t *)kmem_zalloc(KMEM_DUMP_LOGS *
2274 sizeof (kmem_dump_log_t), KM_SLEEP);
2275
2276 kmem_dump_start = kmem_alloc(size, KM_SLEEP);
2277
2278 if (kmem_dump_start != NULL) {
2279 kmem_dump_size = size;
2280 kmem_dump_curr = kmem_dump_start;
2281 kmem_dump_end = (void *)((char *)kmem_dump_start + size);
2282 copy_pattern(KMEM_UNINITIALIZED_PATTERN, kmem_dump_start, size);
2283 } else {
2284 kmem_dump_size = 0;
2285 kmem_dump_curr = NULL;
2286 kmem_dump_end = NULL;
2287 }
2288 }
2289
2290 /*
2291 * Set flag for each kmem_cache_t if is safe to use alternate dump
2292 * memory. Called just before panic crash dump starts. Set the flag
2293 * for the calling CPU.
2294 */
2295 void
2296 kmem_dump_begin(void)
2297 {
2298 ASSERT(panicstr != NULL);
2299 if (kmem_dump_start != NULL) {
2300 kmem_cache_t *cp;
2301
2302 for (cp = list_head(&kmem_caches); cp != NULL;
2303 cp = list_next(&kmem_caches, cp)) {
2304 kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2305
2306 if (cp->cache_arena->vm_cflags & VMC_DUMPSAFE) {
2307 cp->cache_flags |= KMF_DUMPDIVERT;
2308 ccp->cc_flags |= KMF_DUMPDIVERT;
2309 ccp->cc_dump_rounds = ccp->cc_rounds;
2310 ccp->cc_dump_prounds = ccp->cc_prounds;
2311 ccp->cc_rounds = ccp->cc_prounds = -1;
2312 } else {
2313 cp->cache_flags |= KMF_DUMPUNSAFE;
2314 ccp->cc_flags |= KMF_DUMPUNSAFE;
2315 }
2316 }
2317 }
2318 }
2319
2320 /*
2321 * finished dump intercept
2322 * print any warnings on the console
2323 * return verbose information to dumpsys() in the given buffer
2324 */
2325 size_t
2326 kmem_dump_finish(char *buf, size_t size)
2327 {
2328 int kdi_idx;
2329 int kdi_end = kmem_dump_log_idx;
2330 int percent = 0;
2331 int header = 0;
2332 int warn = 0;
2333 size_t used;
2334 kmem_cache_t *cp;
2335 kmem_dump_log_t *kdl;
2336 char *e = buf + size;
2337 char *p = buf;
2338
2339 if (kmem_dump_size == 0 || kmem_dump_verbose == 0)
2340 return (0);
2341
2342 used = (char *)kmem_dump_curr - (char *)kmem_dump_start;
2343 percent = (used * 100) / kmem_dump_size;
2344
2345 kmem_dumppr(&p, e, "%% heap used,%d\n", percent);
2346 kmem_dumppr(&p, e, "used bytes,%ld\n", used);
2347 kmem_dumppr(&p, e, "heap size,%ld\n", kmem_dump_size);
2348 kmem_dumppr(&p, e, "Oversize allocs,%d\n",
2349 kmem_dump_oversize_allocs);
2350 kmem_dumppr(&p, e, "Oversize max size,%ld\n",
2351 kmem_dump_oversize_max);
2352
2353 for (kdi_idx = 0; kdi_idx < kdi_end; kdi_idx++) {
2354 kdl = &kmem_dump_log[kdi_idx];
2355 cp = kdl->kdl_cache;
2356 if (cp == NULL)
2357 break;
2358 if (kdl->kdl_alloc_fails)
2359 ++warn;
2360 if (header == 0) {
2361 kmem_dumppr(&p, e,
2362 "Cache Name,Allocs,Frees,Alloc Fails,"
2363 "Nondump Frees,Unsafe Allocs/Frees\n");
2364 header = 1;
2365 }
2366 kmem_dumppr(&p, e, "%s,%d,%d,%d,%d,%d\n",
2367 cp->cache_name, kdl->kdl_allocs, kdl->kdl_frees,
2368 kdl->kdl_alloc_fails, kdl->kdl_free_nondump,
2369 kdl->kdl_unsafe);
2370 }
2371
2372 /* return buffer size used */
2373 if (p < e)
2374 bzero(p, e - p);
2375 return (p - buf);
2376 }
2377
2378 /*
2379 * Allocate a constructed object from alternate dump memory.
2380 */
2381 void *
2382 kmem_cache_alloc_dump(kmem_cache_t *cp, int kmflag)
2383 {
2384 void *buf;
2385 void *curr;
2386 char *bufend;
2387
2388 /* return a constructed object */
2389 if ((buf = cp->cache_dumpfreelist) != NULL) {
2390 cp->cache_dumpfreelist = KMEM_DUMPCTL(cp, buf)->kdc_next;
2391 KDI_LOG(cp, kdl_allocs);
2392 return (buf);
2393 }
2394
2395 /* create a new constructed object */
2396 curr = kmem_dump_curr;
2397 buf = (void *)P2ROUNDUP((uintptr_t)curr, cp->cache_align);
2398 bufend = (char *)KMEM_DUMPCTL(cp, buf) + sizeof (kmem_dumpctl_t);
2399
2400 /* hat layer objects cannot cross a page boundary */
2401 if (cp->cache_align < PAGESIZE) {
2402 char *page = (char *)P2ROUNDUP((uintptr_t)buf, PAGESIZE);
2403 if (bufend > page) {
2404 bufend += page - (char *)buf;
2405 buf = (void *)page;
2406 }
2407 }
2408
2409 /* fall back to normal alloc if reserved area is used up */
2410 if (bufend > (char *)kmem_dump_end) {
2411 kmem_dump_curr = kmem_dump_end;
2412 KDI_LOG(cp, kdl_alloc_fails);
2413 return (NULL);
2414 }
2415
2416 /*
2417 * Must advance curr pointer before calling a constructor that
2418 * may also allocate memory.
2419 */
2420 kmem_dump_curr = bufend;
2421
2422 /* run constructor */
2423 if (cp->cache_constructor != NULL &&
2424 cp->cache_constructor(buf, cp->cache_private, kmflag)
2425 != 0) {
2426 #ifdef DEBUG
2427 printf("name='%s' cache=0x%p: kmem cache constructor failed\n",
2428 cp->cache_name, (void *)cp);
2429 #endif
2430 /* reset curr pointer iff no allocs were done */
2431 if (kmem_dump_curr == bufend)
2432 kmem_dump_curr = curr;
2433
2434 /* fall back to normal alloc if the constructor fails */
2435 KDI_LOG(cp, kdl_alloc_fails);
2436 return (NULL);
2437 }
2438
2439 KDI_LOG(cp, kdl_allocs);
2440 return (buf);
2441 }
2442
2443 /*
2444 * Free a constructed object in alternate dump memory.
2445 */
2446 int
2447 kmem_cache_free_dump(kmem_cache_t *cp, void *buf)
2448 {
2449 /* save constructed buffers for next time */
2450 if ((char *)buf >= (char *)kmem_dump_start &&
2451 (char *)buf < (char *)kmem_dump_end) {
2452 KMEM_DUMPCTL(cp, buf)->kdc_next = cp->cache_dumpfreelist;
2453 cp->cache_dumpfreelist = buf;
2454 KDI_LOG(cp, kdl_frees);
2455 return (0);
2456 }
2457
2458 /* count all non-dump buf frees */
2459 KDI_LOG(cp, kdl_free_nondump);
2460
2461 /* just drop buffers that were allocated before dump started */
2462 if (kmem_dump_curr < kmem_dump_end)
2463 return (0);
2464
2465 /* fall back to normal free if reserved area is used up */
2466 return (1);
2467 }
2468
2469 /*
2470 * Allocate a constructed object from cache cp.
2471 */
2472 void *
2473 kmem_cache_alloc(kmem_cache_t *cp, int kmflag)
2474 {
2475 kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2476 kmem_magazine_t *fmp;
2477 void *buf;
2478
2479 mutex_enter(&ccp->cc_lock);
2480 for (;;) {
2481 /*
2482 * If there's an object available in the current CPU's
2483 * loaded magazine, just take it and return.
2484 */
2485 if (ccp->cc_rounds > 0) {
2486 buf = ccp->cc_loaded->mag_round[--ccp->cc_rounds];
2487 ccp->cc_alloc++;
2488 mutex_exit(&ccp->cc_lock);
2489 if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPUNSAFE)) {
2490 if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2491 ASSERT(!(ccp->cc_flags &
2492 KMF_DUMPDIVERT));
2493 KDI_LOG(cp, kdl_unsafe);
2494 }
2495 if ((ccp->cc_flags & KMF_BUFTAG) &&
2496 kmem_cache_alloc_debug(cp, buf, kmflag, 0,
2497 caller()) != 0) {
2498 if (kmflag & KM_NOSLEEP)
2499 return (NULL);
2500 mutex_enter(&ccp->cc_lock);
2501 continue;
2502 }
2503 }
2504 return (buf);
2505 }
2506
2507 /*
2508 * The loaded magazine is empty. If the previously loaded
2509 * magazine was full, exchange them and try again.
2510 */
2511 if (ccp->cc_prounds > 0) {
2512 kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2513 continue;
2514 }
2515
2516 /*
2517 * Return an alternate buffer at dump time to preserve
2518 * the heap.
2519 */
2520 if (ccp->cc_flags & (KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2521 if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2522 ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2523 /* log it so that we can warn about it */
2524 KDI_LOG(cp, kdl_unsafe);
2525 } else {
2526 if ((buf = kmem_cache_alloc_dump(cp, kmflag)) !=
2527 NULL) {
2528 mutex_exit(&ccp->cc_lock);
2529 return (buf);
2530 }
2531 break; /* fall back to slab layer */
2532 }
2533 }
2534
2535 /*
2536 * If the magazine layer is disabled, break out now.
2537 */
2538 if (ccp->cc_magsize == 0)
2539 break;
2540
2541 /*
2542 * Try to get a full magazine from the depot.
2543 */
2544 fmp = kmem_depot_alloc(cp, &cp->cache_full);
2545 if (fmp != NULL) {
2546 if (ccp->cc_ploaded != NULL)
2547 kmem_depot_free(cp, &cp->cache_empty,
2548 ccp->cc_ploaded);
2549 kmem_cpu_reload(ccp, fmp, ccp->cc_magsize);
2550 continue;
2551 }
2552
2553 /*
2554 * There are no full magazines in the depot,
2555 * so fall through to the slab layer.
2556 */
2557 break;
2558 }
2559 mutex_exit(&ccp->cc_lock);
2560
2561 /*
2562 * We couldn't allocate a constructed object from the magazine layer,
2563 * so get a raw buffer from the slab layer and apply its constructor.
2564 */
2565 buf = kmem_slab_alloc(cp, kmflag);
2566
2567 if (buf == NULL)
2568 return (NULL);
2569
2570 if (cp->cache_flags & KMF_BUFTAG) {
2571 /*
2572 * Make kmem_cache_alloc_debug() apply the constructor for us.
2573 */
2574 int rc = kmem_cache_alloc_debug(cp, buf, kmflag, 1, caller());
2575 if (rc != 0) {
2576 if (kmflag & KM_NOSLEEP)
2577 return (NULL);
2578 /*
2579 * kmem_cache_alloc_debug() detected corruption
2580 * but didn't panic (kmem_panic <= 0). We should not be
2581 * here because the constructor failed (indicated by a
2582 * return code of 1). Try again.
2583 */
2584 ASSERT(rc == -1);
2585 return (kmem_cache_alloc(cp, kmflag));
2586 }
2587 return (buf);
2588 }
2589
2590 if (cp->cache_constructor != NULL &&
2591 cp->cache_constructor(buf, cp->cache_private, kmflag) != 0) {
2592 atomic_inc_64(&cp->cache_alloc_fail);
2593 kmem_slab_free(cp, buf);
2594 return (NULL);
2595 }
2596
2597 return (buf);
2598 }
2599
2600 /*
2601 * The freed argument tells whether or not kmem_cache_free_debug() has already
2602 * been called so that we can avoid the duplicate free error. For example, a
2603 * buffer on a magazine has already been freed by the client but is still
2604 * constructed.
2605 */
2606 static void
2607 kmem_slab_free_constructed(kmem_cache_t *cp, void *buf, boolean_t freed)
2608 {
2609 if (!freed && (cp->cache_flags & KMF_BUFTAG))
2610 if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2611 return;
2612
2613 /*
2614 * Note that if KMF_DEADBEEF is in effect and KMF_LITE is not,
2615 * kmem_cache_free_debug() will have already applied the destructor.
2616 */
2617 if ((cp->cache_flags & (KMF_DEADBEEF | KMF_LITE)) != KMF_DEADBEEF &&
2618 cp->cache_destructor != NULL) {
2619 if (cp->cache_flags & KMF_DEADBEEF) { /* KMF_LITE implied */
2620 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2621 *(uint64_t *)buf = btp->bt_redzone;
2622 cp->cache_destructor(buf, cp->cache_private);
2623 *(uint64_t *)buf = KMEM_FREE_PATTERN;
2624 } else {
2625 cp->cache_destructor(buf, cp->cache_private);
2626 }
2627 }
2628
2629 kmem_slab_free(cp, buf);
2630 }
2631
2632 /*
2633 * Used when there's no room to free a buffer to the per-CPU cache.
2634 * Drops and re-acquires &ccp->cc_lock, and returns non-zero if the
2635 * caller should try freeing to the per-CPU cache again.
2636 * Note that we don't directly install the magazine in the cpu cache,
2637 * since its state may have changed wildly while the lock was dropped.
2638 */
2639 static int
2640 kmem_cpucache_magazine_alloc(kmem_cpu_cache_t *ccp, kmem_cache_t *cp)
2641 {
2642 kmem_magazine_t *emp;
2643 kmem_magtype_t *mtp;
2644
2645 ASSERT(MUTEX_HELD(&ccp->cc_lock));
2646 ASSERT(((uint_t)ccp->cc_rounds == ccp->cc_magsize ||
2647 ((uint_t)ccp->cc_rounds == -1)) &&
2648 ((uint_t)ccp->cc_prounds == ccp->cc_magsize ||
2649 ((uint_t)ccp->cc_prounds == -1)));
2650
2651 emp = kmem_depot_alloc(cp, &cp->cache_empty);
2652 if (emp != NULL) {
2653 if (ccp->cc_ploaded != NULL)
2654 kmem_depot_free(cp, &cp->cache_full,
2655 ccp->cc_ploaded);
2656 kmem_cpu_reload(ccp, emp, 0);
2657 return (1);
2658 }
2659 /*
2660 * There are no empty magazines in the depot,
2661 * so try to allocate a new one. We must drop all locks
2662 * across kmem_cache_alloc() because lower layers may
2663 * attempt to allocate from this cache.
2664 */
2665 mtp = cp->cache_magtype;
2666 mutex_exit(&ccp->cc_lock);
2667 emp = kmem_cache_alloc(mtp->mt_cache, KM_NOSLEEP);
2668 mutex_enter(&ccp->cc_lock);
2669
2670 if (emp != NULL) {
2671 /*
2672 * We successfully allocated an empty magazine.
2673 * However, we had to drop ccp->cc_lock to do it,
2674 * so the cache's magazine size may have changed.
2675 * If so, free the magazine and try again.
2676 */
2677 if (ccp->cc_magsize != mtp->mt_magsize) {
2678 mutex_exit(&ccp->cc_lock);
2679 kmem_cache_free(mtp->mt_cache, emp);
2680 mutex_enter(&ccp->cc_lock);
2681 return (1);
2682 }
2683
2684 /*
2685 * We got a magazine of the right size. Add it to
2686 * the depot and try the whole dance again.
2687 */
2688 kmem_depot_free(cp, &cp->cache_empty, emp);
2689 return (1);
2690 }
2691
2692 /*
2693 * We couldn't allocate an empty magazine,
2694 * so fall through to the slab layer.
2695 */
2696 return (0);
2697 }
2698
2699 /*
2700 * Free a constructed object to cache cp.
2701 */
2702 void
2703 kmem_cache_free(kmem_cache_t *cp, void *buf)
2704 {
2705 kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2706
2707 /*
2708 * The client must not free either of the buffers passed to the move
2709 * callback function.
2710 */
2711 ASSERT(cp->cache_defrag == NULL ||
2712 cp->cache_defrag->kmd_thread != curthread ||
2713 (buf != cp->cache_defrag->kmd_from_buf &&
2714 buf != cp->cache_defrag->kmd_to_buf));
2715
2716 if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2717 if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2718 ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2719 /* log it so that we can warn about it */
2720 KDI_LOG(cp, kdl_unsafe);
2721 } else if (KMEM_DUMPCC(ccp) && !kmem_cache_free_dump(cp, buf)) {
2722 return;
2723 }
2724 if (ccp->cc_flags & KMF_BUFTAG) {
2725 if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2726 return;
2727 }
2728 }
2729
2730 mutex_enter(&ccp->cc_lock);
2731 /*
2732 * Any changes to this logic should be reflected in kmem_slab_prefill()
2733 */
2734 for (;;) {
2735 /*
2736 * If there's a slot available in the current CPU's
2737 * loaded magazine, just put the object there and return.
2738 */
2739 if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2740 ccp->cc_loaded->mag_round[ccp->cc_rounds++] = buf;
2741 ccp->cc_free++;
2742 mutex_exit(&ccp->cc_lock);
2743 return;
2744 }
2745
2746 /*
2747 * The loaded magazine is full. If the previously loaded
2748 * magazine was empty, exchange them and try again.
2749 */
2750 if (ccp->cc_prounds == 0) {
2751 kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2752 continue;
2753 }
2754
2755 /*
2756 * If the magazine layer is disabled, break out now.
2757 */
2758 if (ccp->cc_magsize == 0)
2759 break;
2760
2761 if (!kmem_cpucache_magazine_alloc(ccp, cp)) {
2762 /*
2763 * We couldn't free our constructed object to the
2764 * magazine layer, so apply its destructor and free it
2765 * to the slab layer.
2766 */
2767 break;
2768 }
2769 }
2770 mutex_exit(&ccp->cc_lock);
2771 kmem_slab_free_constructed(cp, buf, B_TRUE);
2772 }
2773
2774 static void
2775 kmem_slab_prefill(kmem_cache_t *cp, kmem_slab_t *sp)
2776 {
2777 kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2778 int cache_flags = cp->cache_flags;
2779
2780 kmem_bufctl_t *next, *head;
2781 size_t nbufs;
2782
2783 /*
2784 * Completely allocate the newly created slab and put the pre-allocated
2785 * buffers in magazines. Any of the buffers that cannot be put in
2786 * magazines must be returned to the slab.
2787 */
2788 ASSERT(MUTEX_HELD(&cp->cache_lock));
2789 ASSERT((cache_flags & (KMF_PREFILL|KMF_BUFTAG)) == KMF_PREFILL);
2790 ASSERT(cp->cache_constructor == NULL);
2791 ASSERT(sp->slab_cache == cp);
2792 ASSERT(sp->slab_refcnt == 1);
2793 ASSERT(sp->slab_head != NULL && sp->slab_chunks > sp->slab_refcnt);
2794 ASSERT(avl_find(&cp->cache_partial_slabs, sp, NULL) == NULL);
2795
2796 head = sp->slab_head;
2797 nbufs = (sp->slab_chunks - sp->slab_refcnt);
2798 sp->slab_head = NULL;
2799 sp->slab_refcnt += nbufs;
2800 cp->cache_bufslab -= nbufs;
2801 cp->cache_slab_alloc += nbufs;
2802 list_insert_head(&cp->cache_complete_slabs, sp);
2803 cp->cache_complete_slab_count++;
2804 mutex_exit(&cp->cache_lock);
2805 mutex_enter(&ccp->cc_lock);
2806
2807 while (head != NULL) {
2808 void *buf = KMEM_BUF(cp, head);
2809 /*
2810 * If there's a slot available in the current CPU's
2811 * loaded magazine, just put the object there and
2812 * continue.
2813 */
2814 if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2815 ccp->cc_loaded->mag_round[ccp->cc_rounds++] =
2816 buf;
2817 ccp->cc_free++;
2818 nbufs--;
2819 head = head->bc_next;
2820 continue;
2821 }
2822
2823 /*
2824 * The loaded magazine is full. If the previously
2825 * loaded magazine was empty, exchange them and try
2826 * again.
2827 */
2828 if (ccp->cc_prounds == 0) {
2829 kmem_cpu_reload(ccp, ccp->cc_ploaded,
2830 ccp->cc_prounds);
2831 continue;
2832 }
2833
2834 /*
2835 * If the magazine layer is disabled, break out now.
2836 */
2837
2838 if (ccp->cc_magsize == 0) {
2839 break;
2840 }
2841
2842 if (!kmem_cpucache_magazine_alloc(ccp, cp))
2843 break;
2844 }
2845 mutex_exit(&ccp->cc_lock);
2846 if (nbufs != 0) {
2847 ASSERT(head != NULL);
2848
2849 /*
2850 * If there was a failure, return remaining objects to
2851 * the slab
2852 */
2853 while (head != NULL) {
2854 ASSERT(nbufs != 0);
2855 next = head->bc_next;
2856 head->bc_next = NULL;
2857 kmem_slab_free(cp, KMEM_BUF(cp, head));
2858 head = next;
2859 nbufs--;
2860 }
2861 }
2862 ASSERT(head == NULL);
2863 ASSERT(nbufs == 0);
2864 mutex_enter(&cp->cache_lock);
2865 }
2866
2867 void *
2868 kmem_zalloc(size_t size, int kmflag)
2869 {
2870 size_t index;
2871 void *buf;
2872
2873 if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2874 kmem_cache_t *cp = kmem_alloc_table[index];
2875 buf = kmem_cache_alloc(cp, kmflag);
2876 if (buf != NULL) {
2877 if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2878 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2879 ((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2880 ((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2881
2882 if (cp->cache_flags & KMF_LITE) {
2883 KMEM_BUFTAG_LITE_ENTER(btp,
2884 kmem_lite_count, caller());
2885 }
2886 }
2887 bzero(buf, size);
2888 }
2889 } else {
2890 buf = kmem_alloc(size, kmflag);
2891 if (buf != NULL)
2892 bzero(buf, size);
2893 }
2894 return (buf);
2895 }
2896
2897 void *
2898 kmem_alloc(size_t size, int kmflag)
2899 {
2900 size_t index;
2901 kmem_cache_t *cp;
2902 void *buf;
2903
2904 if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2905 cp = kmem_alloc_table[index];
2906 /* fall through to kmem_cache_alloc() */
2907
2908 } else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2909 kmem_big_alloc_table_max) {
2910 cp = kmem_big_alloc_table[index];
2911 /* fall through to kmem_cache_alloc() */
2912
2913 } else {
2914 if (size == 0)
2915 return (NULL);
2916
2917 buf = vmem_alloc(kmem_oversize_arena, size,
2918 kmflag & KM_VMFLAGS);
2919 if (buf == NULL)
2920 kmem_log_event(kmem_failure_log, NULL, NULL,
2921 (void *)size);
2922 else if (KMEM_DUMP(kmem_slab_cache)) {
2923 /* stats for dump intercept */
2924 kmem_dump_oversize_allocs++;
2925 if (size > kmem_dump_oversize_max)
2926 kmem_dump_oversize_max = size;
2927 }
2928 return (buf);
2929 }
2930
2931 buf = kmem_cache_alloc(cp, kmflag);
2932 if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp) && buf != NULL) {
2933 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2934 ((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2935 ((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2936
2937 if (cp->cache_flags & KMF_LITE) {
2938 KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller());
2939 }
2940 }
2941 return (buf);
2942 }
2943
2944 void
2945 kmem_free(void *buf, size_t size)
2946 {
2947 size_t index;
2948 kmem_cache_t *cp;
2949
2950 if ((index = (size - 1) >> KMEM_ALIGN_SHIFT) < KMEM_ALLOC_TABLE_MAX) {
2951 cp = kmem_alloc_table[index];
2952 /* fall through to kmem_cache_free() */
2953
2954 } else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2955 kmem_big_alloc_table_max) {
2956 cp = kmem_big_alloc_table[index];
2957 /* fall through to kmem_cache_free() */
2958
2959 } else {
2960 EQUIV(buf == NULL, size == 0);
2961 if (buf == NULL && size == 0)
2962 return;
2963 vmem_free(kmem_oversize_arena, buf, size);
2964 return;
2965 }
2966
2967 if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2968 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2969 uint32_t *ip = (uint32_t *)btp;
2970 if (ip[1] != KMEM_SIZE_ENCODE(size)) {
2971 if (*(uint64_t *)buf == KMEM_FREE_PATTERN) {
2972 kmem_error(KMERR_DUPFREE, cp, buf);
2973 return;
2974 }
2975 if (KMEM_SIZE_VALID(ip[1])) {
2976 ip[0] = KMEM_SIZE_ENCODE(size);
2977 kmem_error(KMERR_BADSIZE, cp, buf);
2978 } else {
2979 kmem_error(KMERR_REDZONE, cp, buf);
2980 }
2981 return;
2982 }
2983 if (((uint8_t *)buf)[size] != KMEM_REDZONE_BYTE) {
2984 kmem_error(KMERR_REDZONE, cp, buf);
2985 return;
2986 }
2987 btp->bt_redzone = KMEM_REDZONE_PATTERN;
2988 if (cp->cache_flags & KMF_LITE) {
2989 KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count,
2990 caller());
2991 }
2992 }
2993 kmem_cache_free(cp, buf);
2994 }
2995
2996 void *
2997 kmem_firewall_va_alloc(vmem_t *vmp, size_t size, int vmflag)
2998 {
2999 size_t realsize = size + vmp->vm_quantum;
3000 void *addr;
3001
3002 /*
3003 * Annoying edge case: if 'size' is just shy of ULONG_MAX, adding
3004 * vm_quantum will cause integer wraparound. Check for this, and
3005 * blow off the firewall page in this case. Note that such a
3006 * giant allocation (the entire kernel address space) can never
3007 * be satisfied, so it will either fail immediately (VM_NOSLEEP)
3008 * or sleep forever (VM_SLEEP). Thus, there is no need for a
3009 * corresponding check in kmem_firewall_va_free().
3010 */
3011 if (realsize < size)
3012 realsize = size;
3013
3014 /*
3015 * While boot still owns resource management, make sure that this
3016 * redzone virtual address allocation is properly accounted for in
3017 * OBPs "virtual-memory" "available" lists because we're
3018 * effectively claiming them for a red zone. If we don't do this,
3019 * the available lists become too fragmented and too large for the
3020 * current boot/kernel memory list interface.
3021 */
3022 addr = vmem_alloc(vmp, realsize, vmflag | VM_NEXTFIT);
3023
3024 if (addr != NULL && kvseg.s_base == NULL && realsize != size)
3025 (void) boot_virt_alloc((char *)addr + size, vmp->vm_quantum);
3026
3027 return (addr);
3028 }
3029
3030 void
3031 kmem_firewall_va_free(vmem_t *vmp, void *addr, size_t size)
3032 {
3033 ASSERT((kvseg.s_base == NULL ?
3034 va_to_pfn((char *)addr + size) :
3035 hat_getpfnum(kas.a_hat, (caddr_t)addr + size)) == PFN_INVALID);
3036
3037 vmem_free(vmp, addr, size + vmp->vm_quantum);
3038 }
3039
3040 /*
3041 * Try to allocate at least `size' bytes of memory without sleeping or
3042 * panicking. Return actual allocated size in `asize'. If allocation failed,
3043 * try final allocation with sleep or panic allowed.
3044 */
3045 void *
3046 kmem_alloc_tryhard(size_t size, size_t *asize, int kmflag)
3047 {
3048 void *p;
3049
3050 *asize = P2ROUNDUP(size, KMEM_ALIGN);
3051 do {
3052 p = kmem_alloc(*asize, (kmflag | KM_NOSLEEP) & ~KM_PANIC);
3053 if (p != NULL)
3054 return (p);
3055 *asize += KMEM_ALIGN;
3056 } while (*asize <= PAGESIZE);
3057
3058 *asize = P2ROUNDUP(size, KMEM_ALIGN);
3059 return (kmem_alloc(*asize, kmflag));
3060 }
3061
3062 /*
3063 * Reclaim all unused memory from a cache.
3064 */
3065 static void
3066 kmem_cache_reap(kmem_cache_t *cp)
3067 {
3068 ASSERT(taskq_member(kmem_taskq, curthread));
3069 cp->cache_reap++;
3070
3071 /*
3072 * Ask the cache's owner to free some memory if possible.
3073 * The idea is to handle things like the inode cache, which
3074 * typically sits on a bunch of memory that it doesn't truly
3075 * *need*. Reclaim policy is entirely up to the owner; this
3076 * callback is just an advisory plea for help.
3077 */
3078 if (cp->cache_reclaim != NULL) {
3079 long delta;
3080
3081 /*
3082 * Reclaimed memory should be reapable (not included in the
3083 * depot's working set).
3084 */
3085 delta = cp->cache_full.ml_total;
3086 cp->cache_reclaim(cp->cache_private);
3087 delta = cp->cache_full.ml_total - delta;
3088 if (delta > 0) {
3089 mutex_enter(&cp->cache_depot_lock);
3090 cp->cache_full.ml_reaplimit += delta;
3091 cp->cache_full.ml_min += delta;
3092 mutex_exit(&cp->cache_depot_lock);
3093 }
3094 }
3095
3096 kmem_depot_ws_reap(cp);
3097
3098 if (cp->cache_defrag != NULL && !kmem_move_noreap) {
3099 kmem_cache_defrag(cp);
3100 }
3101 }
3102
3103 static void
3104 kmem_reap_timeout(void *flag_arg)
3105 {
3106 uint32_t *flag = (uint32_t *)flag_arg;
3107
3108 ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3109 *flag = 0;
3110 }
3111
3112 static void
3113 kmem_reap_done(void *flag)
3114 {
3115 if (!callout_init_done) {
3116 /* can't schedule a timeout at this point */
3117 kmem_reap_timeout(flag);
3118 } else {
3119 (void) timeout(kmem_reap_timeout, flag, kmem_reap_interval);
3120 }
3121 }
3122
3123 static void
3124 kmem_reap_start(void *flag)
3125 {
3126 ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3127
3128 if (flag == &kmem_reaping) {
3129 kmem_cache_applyall(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3130 /*
3131 * if we have segkp under heap, reap segkp cache.
3132 */
3133 if (segkp_fromheap)
3134 segkp_cache_free();
3135 }
3136 else
3137 kmem_cache_applyall_id(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3138
3139 /*
3140 * We use taskq_dispatch() to schedule a timeout to clear
3141 * the flag so that kmem_reap() becomes self-throttling:
3142 * we won't reap again until the current reap completes *and*
3143 * at least kmem_reap_interval ticks have elapsed.
3144 */
3145 if (!taskq_dispatch(kmem_taskq, kmem_reap_done, flag, TQ_NOSLEEP))
3146 kmem_reap_done(flag);
3147 }
3148
3149 static void
3150 kmem_reap_common(void *flag_arg)
3151 {
3152 uint32_t *flag = (uint32_t *)flag_arg;
3153
3154 if (MUTEX_HELD(&kmem_cache_lock) || kmem_taskq == NULL ||
3155 atomic_cas_32(flag, 0, 1) != 0)
3156 return;
3157
3158 /*
3159 * It may not be kosher to do memory allocation when a reap is called
3160 * (for example, if vmem_populate() is in the call chain). So we
3161 * start the reap going with a TQ_NOALLOC dispatch. If the dispatch
3162 * fails, we reset the flag, and the next reap will try again.
3163 */
3164 if (!taskq_dispatch(kmem_taskq, kmem_reap_start, flag, TQ_NOALLOC))
3165 *flag = 0;
3166 }
3167
3168 /*
3169 * Reclaim all unused memory from all caches. Called from the VM system
3170 * when memory gets tight.
3171 */
3172 void
3173 kmem_reap(void)
3174 {
3175 kmem_reap_common(&kmem_reaping);
3176 }
3177
3178 /*
3179 * Reclaim all unused memory from identifier arenas, called when a vmem
3180 * arena not back by memory is exhausted. Since reaping memory-backed caches
3181 * cannot help with identifier exhaustion, we avoid both a large amount of
3182 * work and unwanted side-effects from reclaim callbacks.
3183 */
3184 void
3185 kmem_reap_idspace(void)
3186 {
3187 kmem_reap_common(&kmem_reaping_idspace);
3188 }
3189
3190 /*
3191 * Purge all magazines from a cache and set its magazine limit to zero.
3192 * All calls are serialized by the kmem_taskq lock, except for the final
3193 * call from kmem_cache_destroy().
3194 */
3195 static void
3196 kmem_cache_magazine_purge(kmem_cache_t *cp)
3197 {
3198 kmem_cpu_cache_t *ccp;
3199 kmem_magazine_t *mp, *pmp;
3200 int rounds, prounds, cpu_seqid;
3201
3202 ASSERT(!list_link_active(&cp->cache_link) ||
3203 taskq_member(kmem_taskq, curthread));
3204 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
3205
3206 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3207 ccp = &cp->cache_cpu[cpu_seqid];
3208
3209 mutex_enter(&ccp->cc_lock);
3210 mp = ccp->cc_loaded;
3211 pmp = ccp->cc_ploaded;
3212 rounds = ccp->cc_rounds;
3213 prounds = ccp->cc_prounds;
3214 ccp->cc_loaded = NULL;
3215 ccp->cc_ploaded = NULL;
3216 ccp->cc_rounds = -1;
3217 ccp->cc_prounds = -1;
3218 ccp->cc_magsize = 0;
3219 mutex_exit(&ccp->cc_lock);
3220
3221 if (mp)
3222 kmem_magazine_destroy(cp, mp, rounds);
3223 if (pmp)
3224 kmem_magazine_destroy(cp, pmp, prounds);
3225 }
3226
3227 kmem_depot_ws_zero(cp);
3228 kmem_depot_ws_reap(cp);
3229 }
3230
3231 /*
3232 * Enable per-cpu magazines on a cache.
3233 */
3234 static void
3235 kmem_cache_magazine_enable(kmem_cache_t *cp)
3236 {
3237 int cpu_seqid;
3238
3239 if (cp->cache_flags & KMF_NOMAGAZINE)
3240 return;
3241
3242 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3243 kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3244 mutex_enter(&ccp->cc_lock);
3245 ccp->cc_magsize = cp->cache_magtype->mt_magsize;
3246 mutex_exit(&ccp->cc_lock);
3247 }
3248
3249 }
3250
3251 /*
3252 * Reap (almost) everything right now.
3253 */
3254 void
3255 kmem_cache_reap_now(kmem_cache_t *cp)
3256 {
3257 ASSERT(list_link_active(&cp->cache_link));
3258
3259 kmem_depot_ws_zero(cp);
3260
3261 (void) taskq_dispatch(kmem_taskq,
3262 (task_func_t *)kmem_depot_ws_reap, cp, TQ_SLEEP);
3263 taskq_wait(kmem_taskq);
3264 }
3265
3266 /*
3267 * Recompute a cache's magazine size. The trade-off is that larger magazines
3268 * provide a higher transfer rate with the depot, while smaller magazines
3269 * reduce memory consumption. Magazine resizing is an expensive operation;
3270 * it should not be done frequently.
3271 *
3272 * Changes to the magazine size are serialized by the kmem_taskq lock.
3273 *
3274 * Note: at present this only grows the magazine size. It might be useful
3275 * to allow shrinkage too.
3276 */
3277 static void
3278 kmem_cache_magazine_resize(kmem_cache_t *cp)
3279 {
3280 kmem_magtype_t *mtp = cp->cache_magtype;
3281
3282 ASSERT(taskq_member(kmem_taskq, curthread));
3283
3284 if (cp->cache_chunksize < mtp->mt_maxbuf) {
3285 kmem_cache_magazine_purge(cp);
3286 mutex_enter(&cp->cache_depot_lock);
3287 cp->cache_magtype = ++mtp;
3288 cp->cache_depot_contention_prev =
3289 cp->cache_depot_contention + INT_MAX;
3290 mutex_exit(&cp->cache_depot_lock);
3291 kmem_cache_magazine_enable(cp);
3292 }
3293 }
3294
3295 /*
3296 * Rescale a cache's hash table, so that the table size is roughly the
3297 * cache size. We want the average lookup time to be extremely small.
3298 */
3299 static void
3300 kmem_hash_rescale(kmem_cache_t *cp)
3301 {
3302 kmem_bufctl_t **old_table, **new_table, *bcp;
3303 size_t old_size, new_size, h;
3304
3305 ASSERT(taskq_member(kmem_taskq, curthread));
3306
3307 new_size = MAX(KMEM_HASH_INITIAL,
3308 1 << (highbit(3 * cp->cache_buftotal + 4) - 2));
3309 old_size = cp->cache_hash_mask + 1;
3310
3311 if ((old_size >> 1) <= new_size && new_size <= (old_size << 1))
3312 return;
3313
3314 new_table = vmem_alloc(kmem_hash_arena, new_size * sizeof (void *),
3315 VM_NOSLEEP);
3316 if (new_table == NULL)
3317 return;
3318 bzero(new_table, new_size * sizeof (void *));
3319
3320 mutex_enter(&cp->cache_lock);
3321
3322 old_size = cp->cache_hash_mask + 1;
3323 old_table = cp->cache_hash_table;
3324
3325 cp->cache_hash_mask = new_size - 1;
3326 cp->cache_hash_table = new_table;
3327 cp->cache_rescale++;
3328
3329 for (h = 0; h < old_size; h++) {
3330 bcp = old_table[h];
3331 while (bcp != NULL) {
3332 void *addr = bcp->bc_addr;
3333 kmem_bufctl_t *next_bcp = bcp->bc_next;
3334 kmem_bufctl_t **hash_bucket = KMEM_HASH(cp, addr);
3335 bcp->bc_next = *hash_bucket;
3336 *hash_bucket = bcp;
3337 bcp = next_bcp;
3338 }
3339 }
3340
3341 mutex_exit(&cp->cache_lock);
3342
3343 vmem_free(kmem_hash_arena, old_table, old_size * sizeof (void *));
3344 }
3345
3346 /*
3347 * Perform periodic maintenance on a cache: hash rescaling, depot working-set
3348 * update, magazine resizing, and slab consolidation.
3349 */
3350 static void
3351 kmem_cache_update(kmem_cache_t *cp)
3352 {
3353 int need_hash_rescale = 0;
3354 int need_magazine_resize = 0;
3355
3356 ASSERT(MUTEX_HELD(&kmem_cache_lock));
3357
3358 /*
3359 * If the cache has become much larger or smaller than its hash table,
3360 * fire off a request to rescale the hash table.
3361 */
3362 mutex_enter(&cp->cache_lock);
3363
3364 if ((cp->cache_flags & KMF_HASH) &&
3365 (cp->cache_buftotal > (cp->cache_hash_mask << 1) ||
3366 (cp->cache_buftotal < (cp->cache_hash_mask >> 1) &&
3367 cp->cache_hash_mask > KMEM_HASH_INITIAL)))
3368 need_hash_rescale = 1;
3369
3370 mutex_exit(&cp->cache_lock);
3371
3372 /*
3373 * Update the depot working set statistics.
3374 */
3375 kmem_depot_ws_update(cp);
3376
3377 /*
3378 * If there's a lot of contention in the depot,
3379 * increase the magazine size.
3380 */
3381 mutex_enter(&cp->cache_depot_lock);
3382
3383 if (cp->cache_chunksize < cp->cache_magtype->mt_maxbuf &&
3384 (int)(cp->cache_depot_contention -
3385 cp->cache_depot_contention_prev) > kmem_depot_contention)
3386 need_magazine_resize = 1;
3387
3388 cp->cache_depot_contention_prev = cp->cache_depot_contention;
3389
3390 mutex_exit(&cp->cache_depot_lock);
3391
3392 if (need_hash_rescale)
3393 (void) taskq_dispatch(kmem_taskq,
3394 (task_func_t *)kmem_hash_rescale, cp, TQ_NOSLEEP);
3395
3396 if (need_magazine_resize)
3397 (void) taskq_dispatch(kmem_taskq,
3398 (task_func_t *)kmem_cache_magazine_resize, cp, TQ_NOSLEEP);
3399
3400 if (cp->cache_defrag != NULL)
3401 (void) taskq_dispatch(kmem_taskq,
3402 (task_func_t *)kmem_cache_scan, cp, TQ_NOSLEEP);
3403 }
3404
3405 static void kmem_update(void *);
3406
3407 static void
3408 kmem_update_timeout(void *dummy)
3409 {
3410 (void) timeout(kmem_update, dummy, kmem_reap_interval);
3411 }
3412
3413 static void
3414 kmem_update(void *dummy)
3415 {
3416 kmem_cache_applyall(kmem_cache_update, NULL, TQ_NOSLEEP);
3417
3418 /*
3419 * We use taskq_dispatch() to reschedule the timeout so that
3420 * kmem_update() becomes self-throttling: it won't schedule
3421 * new tasks until all previous tasks have completed.
3422 */
3423 if (!taskq_dispatch(kmem_taskq, kmem_update_timeout, dummy, TQ_NOSLEEP))
3424 kmem_update_timeout(NULL);
3425 }
3426
3427 static int
3428 kmem_cache_kstat_update(kstat_t *ksp, int rw)
3429 {
3430 struct kmem_cache_kstat *kmcp = &kmem_cache_kstat;
3431 kmem_cache_t *cp = ksp->ks_private;
3432 uint64_t cpu_buf_avail;
3433 uint64_t buf_avail = 0;
3434 int cpu_seqid;
3435 long reap;
3436
3437 ASSERT(MUTEX_HELD(&kmem_cache_kstat_lock));
3438
3439 if (rw == KSTAT_WRITE)
3440 return (EACCES);
3441
3442 mutex_enter(&cp->cache_lock);
3443
3444 kmcp->kmc_alloc_fail.value.ui64 = cp->cache_alloc_fail;
3445 kmcp->kmc_alloc.value.ui64 = cp->cache_slab_alloc;
3446 kmcp->kmc_free.value.ui64 = cp->cache_slab_free;
3447 kmcp->kmc_slab_alloc.value.ui64 = cp->cache_slab_alloc;
3448 kmcp->kmc_slab_free.value.ui64 = cp->cache_slab_free;
3449
3450 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3451 kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3452
3453 mutex_enter(&ccp->cc_lock);
3454
3455 cpu_buf_avail = 0;
3456 if (ccp->cc_rounds > 0)
3457 cpu_buf_avail += ccp->cc_rounds;
3458 if (ccp->cc_prounds > 0)
3459 cpu_buf_avail += ccp->cc_prounds;
3460
3461 kmcp->kmc_alloc.value.ui64 += ccp->cc_alloc;
3462 kmcp->kmc_free.value.ui64 += ccp->cc_free;
3463 buf_avail += cpu_buf_avail;
3464
3465 mutex_exit(&ccp->cc_lock);
3466 }
3467
3468 mutex_enter(&cp->cache_depot_lock);
3469
3470 kmcp->kmc_depot_alloc.value.ui64 = cp->cache_full.ml_alloc;
3471 kmcp->kmc_depot_free.value.ui64 = cp->cache_empty.ml_alloc;
3472 kmcp->kmc_depot_contention.value.ui64 = cp->cache_depot_contention;
3473 kmcp->kmc_full_magazines.value.ui64 = cp->cache_full.ml_total;
3474 kmcp->kmc_empty_magazines.value.ui64 = cp->cache_empty.ml_total;
3475 kmcp->kmc_magazine_size.value.ui64 =
3476 (cp->cache_flags & KMF_NOMAGAZINE) ?
3477 0 : cp->cache_magtype->mt_magsize;
3478
3479 kmcp->kmc_alloc.value.ui64 += cp->cache_full.ml_alloc;
3480 kmcp->kmc_free.value.ui64 += cp->cache_empty.ml_alloc;
3481 buf_avail += cp->cache_full.ml_total * cp->cache_magtype->mt_magsize;
3482
3483 reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
3484 reap = MIN(reap, cp->cache_full.ml_total);
3485
3486 mutex_exit(&cp->cache_depot_lock);
3487
3488 kmcp->kmc_buf_size.value.ui64 = cp->cache_bufsize;
3489 kmcp->kmc_align.value.ui64 = cp->cache_align;
3490 kmcp->kmc_chunk_size.value.ui64 = cp->cache_chunksize;
3491 kmcp->kmc_slab_size.value.ui64 = cp->cache_slabsize;
3492 kmcp->kmc_buf_constructed.value.ui64 = buf_avail;
3493 buf_avail += cp->cache_bufslab;
3494 kmcp->kmc_buf_avail.value.ui64 = buf_avail;
3495 kmcp->kmc_buf_inuse.value.ui64 = cp->cache_buftotal - buf_avail;
3496 kmcp->kmc_buf_total.value.ui64 = cp->cache_buftotal;
3497 kmcp->kmc_buf_max.value.ui64 = cp->cache_bufmax;
3498 kmcp->kmc_slab_create.value.ui64 = cp->cache_slab_create;
3499 kmcp->kmc_slab_destroy.value.ui64 = cp->cache_slab_destroy;
3500 kmcp->kmc_hash_size.value.ui64 = (cp->cache_flags & KMF_HASH) ?
3501 cp->cache_hash_mask + 1 : 0;
3502 kmcp->kmc_hash_lookup_depth.value.ui64 = cp->cache_lookup_depth;
3503 kmcp->kmc_hash_rescale.value.ui64 = cp->cache_rescale;
3504 kmcp->kmc_vmem_source.value.ui64 = cp->cache_arena->vm_id;
3505 kmcp->kmc_reap.value.ui64 = cp->cache_reap;
3506
3507 if (cp->cache_defrag == NULL) {
3508 kmcp->kmc_move_callbacks.value.ui64 = 0;
3509 kmcp->kmc_move_yes.value.ui64 = 0;
3510 kmcp->kmc_move_no.value.ui64 = 0;
3511 kmcp->kmc_move_later.value.ui64 = 0;
3512 kmcp->kmc_move_dont_need.value.ui64 = 0;
3513 kmcp->kmc_move_dont_know.value.ui64 = 0;
3514 kmcp->kmc_move_hunt_found.value.ui64 = 0;
3515 kmcp->kmc_move_slabs_freed.value.ui64 = 0;
3516 kmcp->kmc_defrag.value.ui64 = 0;
3517 kmcp->kmc_scan.value.ui64 = 0;
3518 kmcp->kmc_move_reclaimable.value.ui64 = 0;
3519 } else {
3520 int64_t reclaimable;
3521
3522 kmem_defrag_t *kd = cp->cache_defrag;
3523 kmcp->kmc_move_callbacks.value.ui64 = kd->kmd_callbacks;
3524 kmcp->kmc_move_yes.value.ui64 = kd->kmd_yes;
3525 kmcp->kmc_move_no.value.ui64 = kd->kmd_no;
3526 kmcp->kmc_move_later.value.ui64 = kd->kmd_later;
3527 kmcp->kmc_move_dont_need.value.ui64 = kd->kmd_dont_need;
3528 kmcp->kmc_move_dont_know.value.ui64 = kd->kmd_dont_know;
3529 kmcp->kmc_move_hunt_found.value.ui64 = 0;
3530 kmcp->kmc_move_slabs_freed.value.ui64 = kd->kmd_slabs_freed;
3531 kmcp->kmc_defrag.value.ui64 = kd->kmd_defrags;
3532 kmcp->kmc_scan.value.ui64 = kd->kmd_scans;
3533
3534 reclaimable = cp->cache_bufslab - (cp->cache_maxchunks - 1);
3535 reclaimable = MAX(reclaimable, 0);
3536 reclaimable += ((uint64_t)reap * cp->cache_magtype->mt_magsize);
3537 kmcp->kmc_move_reclaimable.value.ui64 = reclaimable;
3538 }
3539
3540 mutex_exit(&cp->cache_lock);
3541 return (0);
3542 }
3543
3544 /*
3545 * Return a named statistic about a particular cache.
3546 * This shouldn't be called very often, so it's currently designed for
3547 * simplicity (leverages existing kstat support) rather than efficiency.
3548 */
3549 uint64_t
3550 kmem_cache_stat(kmem_cache_t *cp, char *name)
3551 {
3552 int i;
3553 kstat_t *ksp = cp->cache_kstat;
3554 kstat_named_t *knp = (kstat_named_t *)&kmem_cache_kstat;
3555 uint64_t value = 0;
3556
3557 if (ksp != NULL) {
3558 mutex_enter(&kmem_cache_kstat_lock);
3559 (void) kmem_cache_kstat_update(ksp, KSTAT_READ);
3560 for (i = 0; i < ksp->ks_ndata; i++) {
3561 if (strcmp(knp[i].name, name) == 0) {
3562 value = knp[i].value.ui64;
3563 break;
3564 }
3565 }
3566 mutex_exit(&kmem_cache_kstat_lock);
3567 }
3568 return (value);
3569 }
3570
3571 /*
3572 * Return an estimate of currently available kernel heap memory.
3573 * On 32-bit systems, physical memory may exceed virtual memory,
3574 * we just truncate the result at 1GB.
3575 */
3576 size_t
3577 kmem_avail(void)
3578 {
3579 spgcnt_t rmem = availrmem - tune.t_minarmem;
3580 spgcnt_t fmem = freemem - minfree;
3581
3582 return ((size_t)ptob(MIN(MAX(MIN(rmem, fmem), 0),
3583 1 << (30 - PAGESHIFT))));
3584 }
3585
3586 /*
3587 * Return the maximum amount of memory that is (in theory) allocatable
3588 * from the heap. This may be used as an estimate only since there
3589 * is no guarentee this space will still be available when an allocation
3590 * request is made, nor that the space may be allocated in one big request
3591 * due to kernel heap fragmentation.
3592 */
3593 size_t
3594 kmem_maxavail(void)
3595 {
3596 spgcnt_t pmem = availrmem - tune.t_minarmem;
3597 spgcnt_t vmem = btop(vmem_size(heap_arena, VMEM_FREE));
3598
3599 return ((size_t)ptob(MAX(MIN(pmem, vmem), 0)));
3600 }
3601
3602 /*
3603 * Indicate whether memory-intensive kmem debugging is enabled.
3604 */
3605 int
3606 kmem_debugging(void)
3607 {
3608 return (kmem_flags & (KMF_AUDIT | KMF_REDZONE));
3609 }
3610
3611 /* binning function, sorts finely at the two extremes */
3612 #define KMEM_PARTIAL_SLAB_WEIGHT(sp, binshift) \
3613 ((((sp)->slab_refcnt <= (binshift)) || \
3614 (((sp)->slab_chunks - (sp)->slab_refcnt) <= (binshift))) \
3615 ? -(sp)->slab_refcnt \
3616 : -((binshift) + ((sp)->slab_refcnt >> (binshift))))
3617
3618 /*
3619 * Minimizing the number of partial slabs on the freelist minimizes
3620 * fragmentation (the ratio of unused buffers held by the slab layer). There are
3621 * two ways to get a slab off of the freelist: 1) free all the buffers on the
3622 * slab, and 2) allocate all the buffers on the slab. It follows that we want
3623 * the most-used slabs at the front of the list where they have the best chance
3624 * of being completely allocated, and the least-used slabs at a safe distance
3625 * from the front to improve the odds that the few remaining buffers will all be
3626 * freed before another allocation can tie up the slab. For that reason a slab
3627 * with a higher slab_refcnt sorts less than than a slab with a lower
3628 * slab_refcnt.
3629 *
3630 * However, if a slab has at least one buffer that is deemed unfreeable, we
3631 * would rather have that slab at the front of the list regardless of
3632 * slab_refcnt, since even one unfreeable buffer makes the entire slab
3633 * unfreeable. If the client returns KMEM_CBRC_NO in response to a cache_move()
3634 * callback, the slab is marked unfreeable for as long as it remains on the
3635 * freelist.
3636 */
3637 static int
3638 kmem_partial_slab_cmp(const void *p0, const void *p1)
3639 {
3640 const kmem_cache_t *cp;
3641 const kmem_slab_t *s0 = p0;
3642 const kmem_slab_t *s1 = p1;
3643 int w0, w1;
3644 size_t binshift;
3645
3646 ASSERT(KMEM_SLAB_IS_PARTIAL(s0));
3647 ASSERT(KMEM_SLAB_IS_PARTIAL(s1));
3648 ASSERT(s0->slab_cache == s1->slab_cache);
3649 cp = s1->slab_cache;
3650 ASSERT(MUTEX_HELD(&cp->cache_lock));
3651 binshift = cp->cache_partial_binshift;
3652
3653 /* weight of first slab */
3654 w0 = KMEM_PARTIAL_SLAB_WEIGHT(s0, binshift);
3655 if (s0->slab_flags & KMEM_SLAB_NOMOVE) {
3656 w0 -= cp->cache_maxchunks;
3657 }
3658
3659 /* weight of second slab */
3660 w1 = KMEM_PARTIAL_SLAB_WEIGHT(s1, binshift);
3661 if (s1->slab_flags & KMEM_SLAB_NOMOVE) {
3662 w1 -= cp->cache_maxchunks;
3663 }
3664
3665 if (w0 < w1)
3666 return (-1);
3667 if (w0 > w1)
3668 return (1);
3669
3670 /* compare pointer values */
3671 if ((uintptr_t)s0 < (uintptr_t)s1)
3672 return (-1);
3673 if ((uintptr_t)s0 > (uintptr_t)s1)
3674 return (1);
3675
3676 return (0);
3677 }
3678
3679 /*
3680 * It must be valid to call the destructor (if any) on a newly created object.
3681 * That is, the constructor (if any) must leave the object in a valid state for
3682 * the destructor.
3683 */
3684 kmem_cache_t *
3685 kmem_cache_create(
3686 char *name, /* descriptive name for this cache */
3687 size_t bufsize, /* size of the objects it manages */
3688 size_t align, /* required object alignment */
3689 int (*constructor)(void *, void *, int), /* object constructor */
3690 void (*destructor)(void *, void *), /* object destructor */
3691 void (*reclaim)(void *), /* memory reclaim callback */
3692 void *private, /* pass-thru arg for constr/destr/reclaim */
3693 vmem_t *vmp, /* vmem source for slab allocation */
3694 int cflags) /* cache creation flags */
3695 {
3696 int cpu_seqid;
3697 size_t chunksize;
3698 kmem_cache_t *cp;
3699 kmem_magtype_t *mtp;
3700 size_t csize = KMEM_CACHE_SIZE(max_ncpus);
3701
3702 #ifdef DEBUG
3703 /*
3704 * Cache names should conform to the rules for valid C identifiers
3705 */
3706 if (!strident_valid(name)) {
3707 cmn_err(CE_CONT,
3708 "kmem_cache_create: '%s' is an invalid cache name\n"
3709 "cache names must conform to the rules for "
3710 "C identifiers\n", name);
3711 }
3712 #endif /* DEBUG */
3713
3714 if (vmp == NULL)
3715 vmp = kmem_default_arena;
3716
3717 /*
3718 * If this kmem cache has an identifier vmem arena as its source, mark
3719 * it such to allow kmem_reap_idspace().
3720 */
3721 ASSERT(!(cflags & KMC_IDENTIFIER)); /* consumer should not set this */
3722 if (vmp->vm_cflags & VMC_IDENTIFIER)
3723 cflags |= KMC_IDENTIFIER;
3724
3725 /*
3726 * Get a kmem_cache structure. We arrange that cp->cache_cpu[]
3727 * is aligned on a KMEM_CPU_CACHE_SIZE boundary to prevent
3728 * false sharing of per-CPU data.
3729 */
3730 cp = vmem_xalloc(kmem_cache_arena, csize, KMEM_CPU_CACHE_SIZE,
3731 P2NPHASE(csize, KMEM_CPU_CACHE_SIZE), 0, NULL, NULL, VM_SLEEP);
3732 bzero(cp, csize);
3733 list_link_init(&cp->cache_link);
3734
3735 if (align == 0)
3736 align = KMEM_ALIGN;
3737
3738 /*
3739 * If we're not at least KMEM_ALIGN aligned, we can't use free
3740 * memory to hold bufctl information (because we can't safely
3741 * perform word loads and stores on it).
3742 */
3743 if (align < KMEM_ALIGN)
3744 cflags |= KMC_NOTOUCH;
3745
3746 if (!ISP2(align) || align > vmp->vm_quantum)
3747 panic("kmem_cache_create: bad alignment %lu", align);
3748
3749 mutex_enter(&kmem_flags_lock);
3750 if (kmem_flags & KMF_RANDOMIZE)
3751 kmem_flags = (((kmem_flags | ~KMF_RANDOM) + 1) & KMF_RANDOM) |
3752 KMF_RANDOMIZE;
3753 cp->cache_flags = (kmem_flags | cflags) & KMF_DEBUG;
3754 mutex_exit(&kmem_flags_lock);
3755
3756 /*
3757 * Make sure all the various flags are reasonable.
3758 */
3759 ASSERT(!(cflags & KMC_NOHASH) || !(cflags & KMC_NOTOUCH));
3760
3761 if (cp->cache_flags & KMF_LITE) {
3762 if (bufsize >= kmem_lite_minsize &&
3763 align <= kmem_lite_maxalign &&
3764 P2PHASE(bufsize, kmem_lite_maxalign) != 0) {
3765 cp->cache_flags |= KMF_BUFTAG;
3766 cp->cache_flags &= ~(KMF_AUDIT | KMF_FIREWALL);
3767 } else {
3768 cp->cache_flags &= ~KMF_DEBUG;
3769 }
3770 }
3771
3772 if (cp->cache_flags & KMF_DEADBEEF)
3773 cp->cache_flags |= KMF_REDZONE;
3774
3775 if ((cflags & KMC_QCACHE) && (cp->cache_flags & KMF_AUDIT))
3776 cp->cache_flags |= KMF_NOMAGAZINE;
3777
3778 if (cflags & KMC_NODEBUG)
3779 cp->cache_flags &= ~KMF_DEBUG;
3780
3781 if (cflags & KMC_NOTOUCH)
3782 cp->cache_flags &= ~KMF_TOUCH;
3783
3784 if (cflags & KMC_PREFILL)
3785 cp->cache_flags |= KMF_PREFILL;
3786
3787 if (cflags & KMC_NOHASH)
3788 cp->cache_flags &= ~(KMF_AUDIT | KMF_FIREWALL);
3789
3790 if (cflags & KMC_NOMAGAZINE)
3791 cp->cache_flags |= KMF_NOMAGAZINE;
3792
3793 if ((cp->cache_flags & KMF_AUDIT) && !(cflags & KMC_NOTOUCH))
3794 cp->cache_flags |= KMF_REDZONE;
3795
3796 if (!(cp->cache_flags & KMF_AUDIT))
3797 cp->cache_flags &= ~KMF_CONTENTS;
3798
3799 if ((cp->cache_flags & KMF_BUFTAG) && bufsize >= kmem_minfirewall &&
3800 !(cp->cache_flags & KMF_LITE) && !(cflags & KMC_NOHASH))
3801 cp->cache_flags |= KMF_FIREWALL;
3802
3803 if (vmp != kmem_default_arena || kmem_firewall_arena == NULL)
3804 cp->cache_flags &= ~KMF_FIREWALL;
3805
3806 if (cp->cache_flags & KMF_FIREWALL) {
3807 cp->cache_flags &= ~KMF_BUFTAG;
3808 cp->cache_flags |= KMF_NOMAGAZINE;
3809 ASSERT(vmp == kmem_default_arena);
3810 vmp = kmem_firewall_arena;
3811 }
3812
3813 /*
3814 * Set cache properties.
3815 */
3816 (void) strncpy(cp->cache_name, name, KMEM_CACHE_NAMELEN);
3817 strident_canon(cp->cache_name, KMEM_CACHE_NAMELEN + 1);
3818 cp->cache_bufsize = bufsize;
3819 cp->cache_align = align;
3820 cp->cache_constructor = constructor;
3821 cp->cache_destructor = destructor;
3822 cp->cache_reclaim = reclaim;
3823 cp->cache_private = private;
3824 cp->cache_arena = vmp;
3825 cp->cache_cflags = cflags;
3826
3827 /*
3828 * Determine the chunk size.
3829 */
3830 chunksize = bufsize;
3831
3832 if (align >= KMEM_ALIGN) {
3833 chunksize = P2ROUNDUP(chunksize, KMEM_ALIGN);
3834 cp->cache_bufctl = chunksize - KMEM_ALIGN;
3835 }
3836
3837 if (cp->cache_flags & KMF_BUFTAG) {
3838 cp->cache_bufctl = chunksize;
3839 cp->cache_buftag = chunksize;
3840 if (cp->cache_flags & KMF_LITE)
3841 chunksize += KMEM_BUFTAG_LITE_SIZE(kmem_lite_count);
3842 else
3843 chunksize += sizeof (kmem_buftag_t);
3844 }
3845
3846 if (cp->cache_flags & KMF_DEADBEEF) {
3847 cp->cache_verify = MIN(cp->cache_buftag, kmem_maxverify);
3848 if (cp->cache_flags & KMF_LITE)
3849 cp->cache_verify = sizeof (uint64_t);
3850 }
3851
3852 cp->cache_contents = MIN(cp->cache_bufctl, kmem_content_maxsave);
3853
3854 cp->cache_chunksize = chunksize = P2ROUNDUP(chunksize, align);
3855
3856 /*
3857 * Now that we know the chunk size, determine the optimal slab size.
3858 */
3859 if (vmp == kmem_firewall_arena) {
3860 cp->cache_slabsize = P2ROUNDUP(chunksize, vmp->vm_quantum);
3861 cp->cache_mincolor = cp->cache_slabsize - chunksize;
3862 cp->cache_maxcolor = cp->cache_mincolor;
3863 cp->cache_flags |= KMF_HASH;
3864 ASSERT(!(cp->cache_flags & KMF_BUFTAG));
3865 } else if ((cflags & KMC_NOHASH) || (!(cflags & KMC_NOTOUCH) &&
3866 !(cp->cache_flags & KMF_AUDIT) &&
3867 chunksize < vmp->vm_quantum / KMEM_VOID_FRACTION)) {
3868 cp->cache_slabsize = vmp->vm_quantum;
3869 cp->cache_mincolor = 0;
3870 cp->cache_maxcolor =
3871 (cp->cache_slabsize - sizeof (kmem_slab_t)) % chunksize;
3872 ASSERT(chunksize + sizeof (kmem_slab_t) <= cp->cache_slabsize);
3873 ASSERT(!(cp->cache_flags & KMF_AUDIT));
3874 } else {
3875 size_t chunks, bestfit, waste, slabsize;
3876 size_t minwaste = LONG_MAX;
3877
3878 for (chunks = 1; chunks <= KMEM_VOID_FRACTION; chunks++) {
3879 slabsize = P2ROUNDUP(chunksize * chunks,
3880 vmp->vm_quantum);
3881 chunks = slabsize / chunksize;
3882 waste = (slabsize % chunksize) / chunks;
3883 if (waste < minwaste) {
3884 minwaste = waste;
3885 bestfit = slabsize;
3886 }
3887 }
3888 if (cflags & KMC_QCACHE)
3889 bestfit = VMEM_QCACHE_SLABSIZE(vmp->vm_qcache_max);
3890 cp->cache_slabsize = bestfit;
3891 cp->cache_mincolor = 0;
3892 cp->cache_maxcolor = bestfit % chunksize;
3893 cp->cache_flags |= KMF_HASH;
3894 }
3895
3896 cp->cache_maxchunks = (cp->cache_slabsize / cp->cache_chunksize);
3897 cp->cache_partial_binshift = highbit(cp->cache_maxchunks / 16) + 1;
3898
3899 /*
3900 * Disallowing prefill when either the DEBUG or HASH flag is set or when
3901 * there is a constructor avoids some tricky issues with debug setup
3902 * that may be revisited later. We cannot allow prefill in a
3903 * metadata cache because of potential recursion.
3904 */
3905 if (vmp == kmem_msb_arena ||
3906 cp->cache_flags & (KMF_HASH | KMF_BUFTAG) ||
3907 cp->cache_constructor != NULL)
3908 cp->cache_flags &= ~KMF_PREFILL;
3909
3910 if (cp->cache_flags & KMF_HASH) {
3911 ASSERT(!(cflags & KMC_NOHASH));
3912 cp->cache_bufctl_cache = (cp->cache_flags & KMF_AUDIT) ?
3913 kmem_bufctl_audit_cache : kmem_bufctl_cache;
3914 }
3915
3916 if (cp->cache_maxcolor >= vmp->vm_quantum)
3917 cp->cache_maxcolor = vmp->vm_quantum - 1;
3918
3919 cp->cache_color = cp->cache_mincolor;
3920
3921 /*
3922 * Initialize the rest of the slab layer.
3923 */
3924 mutex_init(&cp->cache_lock, NULL, MUTEX_DEFAULT, NULL);
3925
3926 avl_create(&cp->cache_partial_slabs, kmem_partial_slab_cmp,
3927 sizeof (kmem_slab_t), offsetof(kmem_slab_t, slab_link));
3928 /* LINTED: E_TRUE_LOGICAL_EXPR */
3929 ASSERT(sizeof (list_node_t) <= sizeof (avl_node_t));
3930 /* reuse partial slab AVL linkage for complete slab list linkage */
3931 list_create(&cp->cache_complete_slabs,
3932 sizeof (kmem_slab_t), offsetof(kmem_slab_t, slab_link));
3933
3934 if (cp->cache_flags & KMF_HASH) {
3935 cp->cache_hash_table = vmem_alloc(kmem_hash_arena,
3936 KMEM_HASH_INITIAL * sizeof (void *), VM_SLEEP);
3937 bzero(cp->cache_hash_table,
3938 KMEM_HASH_INITIAL * sizeof (void *));
3939 cp->cache_hash_mask = KMEM_HASH_INITIAL - 1;
3940 cp->cache_hash_shift = highbit((ulong_t)chunksize) - 1;
3941 }
3942
3943 /*
3944 * Initialize the depot.
3945 */
3946 mutex_init(&cp->cache_depot_lock, NULL, MUTEX_DEFAULT, NULL);
3947
3948 for (mtp = kmem_magtype; chunksize <= mtp->mt_minbuf; mtp++)
3949 continue;
3950
3951 cp->cache_magtype = mtp;
3952
3953 /*
3954 * Initialize the CPU layer.
3955 */
3956 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3957 kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3958 mutex_init(&ccp->cc_lock, NULL, MUTEX_DEFAULT, NULL);
3959 ccp->cc_flags = cp->cache_flags;
3960 ccp->cc_rounds = -1;
3961 ccp->cc_prounds = -1;
3962 }
3963
3964 /*
3965 * Create the cache's kstats.
3966 */
3967 if ((cp->cache_kstat = kstat_create("unix", 0, cp->cache_name,
3968 "kmem_cache", KSTAT_TYPE_NAMED,
3969 sizeof (kmem_cache_kstat) / sizeof (kstat_named_t),
3970 KSTAT_FLAG_VIRTUAL)) != NULL) {
3971 cp->cache_kstat->ks_data = &kmem_cache_kstat;
3972 cp->cache_kstat->ks_update = kmem_cache_kstat_update;
3973 cp->cache_kstat->ks_private = cp;
3974 cp->cache_kstat->ks_lock = &kmem_cache_kstat_lock;
3975 kstat_install(cp->cache_kstat);
3976 }
3977
3978 /*
3979 * Add the cache to the global list. This makes it visible
3980 * to kmem_update(), so the cache must be ready for business.
3981 */
3982 mutex_enter(&kmem_cache_lock);
3983 list_insert_tail(&kmem_caches, cp);
3984 mutex_exit(&kmem_cache_lock);
3985
3986 if (kmem_ready)
3987 kmem_cache_magazine_enable(cp);
3988
3989 return (cp);
3990 }
3991
3992 static int
3993 kmem_move_cmp(const void *buf, const void *p)
3994 {
3995 const kmem_move_t *kmm = p;
3996 uintptr_t v1 = (uintptr_t)buf;
3997 uintptr_t v2 = (uintptr_t)kmm->kmm_from_buf;
3998 return (v1 < v2 ? -1 : (v1 > v2 ? 1 : 0));
3999 }
4000
4001 static void
4002 kmem_reset_reclaim_threshold(kmem_defrag_t *kmd)
4003 {
4004 kmd->kmd_reclaim_numer = 1;
4005 }
4006
4007 /*
4008 * Initially, when choosing candidate slabs for buffers to move, we want to be
4009 * very selective and take only slabs that are less than
4010 * (1 / KMEM_VOID_FRACTION) allocated. If we have difficulty finding candidate
4011 * slabs, then we raise the allocation ceiling incrementally. The reclaim
4012 * threshold is reset to (1 / KMEM_VOID_FRACTION) as soon as the cache is no
4013 * longer fragmented.
4014 */
4015 static void
4016 kmem_adjust_reclaim_threshold(kmem_defrag_t *kmd, int direction)
4017 {
4018 if (direction > 0) {
4019 /* make it easier to find a candidate slab */
4020 if (kmd->kmd_reclaim_numer < (KMEM_VOID_FRACTION - 1)) {
4021 kmd->kmd_reclaim_numer++;
4022 }
4023 } else {
4024 /* be more selective */
4025 if (kmd->kmd_reclaim_numer > 1) {
4026 kmd->kmd_reclaim_numer--;
4027 }
4028 }
4029 }
4030
4031 void
4032 kmem_cache_set_move(kmem_cache_t *cp,
4033 kmem_cbrc_t (*move)(void *, void *, size_t, void *))
4034 {
4035 kmem_defrag_t *defrag;
4036
4037 ASSERT(move != NULL);
4038 /*
4039 * The consolidator does not support NOTOUCH caches because kmem cannot
4040 * initialize their slabs with the 0xbaddcafe memory pattern, which sets
4041 * a low order bit usable by clients to distinguish uninitialized memory
4042 * from known objects (see kmem_slab_create).
4043 */
4044 ASSERT(!(cp->cache_cflags & KMC_NOTOUCH));
4045 ASSERT(!(cp->cache_cflags & KMC_IDENTIFIER));
4046
4047 /*
4048 * We should not be holding anyone's cache lock when calling
4049 * kmem_cache_alloc(), so allocate in all cases before acquiring the
4050 * lock.
4051 */
4052 defrag = kmem_cache_alloc(kmem_defrag_cache, KM_SLEEP);
4053
4054 mutex_enter(&cp->cache_lock);
4055
4056 if (KMEM_IS_MOVABLE(cp)) {
4057 if (cp->cache_move == NULL) {
4058 ASSERT(cp->cache_slab_alloc == 0);
4059
4060 cp->cache_defrag = defrag;
4061 defrag = NULL; /* nothing to free */
4062 bzero(cp->cache_defrag, sizeof (kmem_defrag_t));
4063 avl_create(&cp->cache_defrag->kmd_moves_pending,
4064 kmem_move_cmp, sizeof (kmem_move_t),
4065 offsetof(kmem_move_t, kmm_entry));
4066 /* LINTED: E_TRUE_LOGICAL_EXPR */
4067 ASSERT(sizeof (list_node_t) <= sizeof (avl_node_t));
4068 /* reuse the slab's AVL linkage for deadlist linkage */
4069 list_create(&cp->cache_defrag->kmd_deadlist,
4070 sizeof (kmem_slab_t),
4071 offsetof(kmem_slab_t, slab_link));
4072 kmem_reset_reclaim_threshold(cp->cache_defrag);
4073 }
4074 cp->cache_move = move;
4075 }
4076
4077 mutex_exit(&cp->cache_lock);
4078
4079 if (defrag != NULL) {
4080 kmem_cache_free(kmem_defrag_cache, defrag); /* unused */
4081 }
4082 }
4083
4084 void
4085 kmem_cache_destroy(kmem_cache_t *cp)
4086 {
4087 int cpu_seqid;
4088
4089 /*
4090 * Remove the cache from the global cache list so that no one else
4091 * can schedule tasks on its behalf, wait for any pending tasks to
4092 * complete, purge the cache, and then destroy it.
4093 */
4094 mutex_enter(&kmem_cache_lock);
4095 list_remove(&kmem_caches, cp);
4096 mutex_exit(&kmem_cache_lock);
4097
4098 if (kmem_taskq != NULL)
4099 taskq_wait(kmem_taskq);
4100
4101 if (kmem_move_taskq != NULL && cp->cache_defrag != NULL)
4102 taskq_wait(kmem_move_taskq);
4103
4104 kmem_cache_magazine_purge(cp);
4105
4106 mutex_enter(&cp->cache_lock);
4107 if (cp->cache_buftotal != 0)
4108 cmn_err(CE_WARN, "kmem_cache_destroy: '%s' (%p) not empty",
4109 cp->cache_name, (void *)cp);
4110 if (cp->cache_defrag != NULL) {
4111 avl_destroy(&cp->cache_defrag->kmd_moves_pending);
4112 list_destroy(&cp->cache_defrag->kmd_deadlist);
4113 kmem_cache_free(kmem_defrag_cache, cp->cache_defrag);
4114 cp->cache_defrag = NULL;
4115 }
4116 /*
4117 * The cache is now dead. There should be no further activity. We
4118 * enforce this by setting land mines in the constructor, destructor,
4119 * reclaim, and move routines that induce a kernel text fault if
4120 * invoked.
4121 */
4122 cp->cache_constructor = (int (*)(void *, void *, int))1;
4123 cp->cache_destructor = (void (*)(void *, void *))2;
4124 cp->cache_reclaim = (void (*)(void *))3;
4125 cp->cache_move = (kmem_cbrc_t (*)(void *, void *, size_t, void *))4;
4126 mutex_exit(&cp->cache_lock);
4127
4128 kstat_delete(cp->cache_kstat);
4129
4130 if (cp->cache_hash_table != NULL)
4131 vmem_free(kmem_hash_arena, cp->cache_hash_table,
4132 (cp->cache_hash_mask + 1) * sizeof (void *));
4133
4134 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++)
4135 mutex_destroy(&cp->cache_cpu[cpu_seqid].cc_lock);
4136
4137 mutex_destroy(&cp->cache_depot_lock);
4138 mutex_destroy(&cp->cache_lock);
4139
4140 vmem_free(kmem_cache_arena, cp, KMEM_CACHE_SIZE(max_ncpus));
4141 }
4142
4143 /*ARGSUSED*/
4144 static int
4145 kmem_cpu_setup(cpu_setup_t what, int id, void *arg)
4146 {
4147 ASSERT(MUTEX_HELD(&cpu_lock));
4148 if (what == CPU_UNCONFIG) {
4149 kmem_cache_applyall(kmem_cache_magazine_purge,
4150 kmem_taskq, TQ_SLEEP);
4151 kmem_cache_applyall(kmem_cache_magazine_enable,
4152 kmem_taskq, TQ_SLEEP);
4153 }
4154 return (0);
4155 }
4156
4157 static void
4158 kmem_alloc_caches_create(const int *array, size_t count,
4159 kmem_cache_t **alloc_table, size_t maxbuf, uint_t shift)
4160 {
4161 char name[KMEM_CACHE_NAMELEN + 1];
4162 size_t table_unit = (1 << shift); /* range of one alloc_table entry */
4163 size_t size = table_unit;
4164 int i;
4165
4166 for (i = 0; i < count; i++) {
4167 size_t cache_size = array[i];
4168 size_t align = KMEM_ALIGN;
4169 kmem_cache_t *cp;
4170
4171 /* if the table has an entry for maxbuf, we're done */
4172 if (size > maxbuf)
4173 break;
4174
4175 /* cache size must be a multiple of the table unit */
4176 ASSERT(P2PHASE(cache_size, table_unit) == 0);
4177
4178 /*
4179 * If they allocate a multiple of the coherency granularity,
4180 * they get a coherency-granularity-aligned address.
4181 */
4182 if (IS_P2ALIGNED(cache_size, 64))
4183 align = 64;
4184 if (IS_P2ALIGNED(cache_size, PAGESIZE))
4185 align = PAGESIZE;
4186 (void) snprintf(name, sizeof (name),
4187 "kmem_alloc_%lu", cache_size);
4188 cp = kmem_cache_create(name, cache_size, align,
4189 NULL, NULL, NULL, NULL, NULL, KMC_KMEM_ALLOC);
4190
4191 while (size <= cache_size) {
4192 alloc_table[(size - 1) >> shift] = cp;
4193 size += table_unit;
4194 }
4195 }
4196
4197 ASSERT(size > maxbuf); /* i.e. maxbuf <= max(cache_size) */
4198 }
4199
4200 static void
4201 kmem_cache_init(int pass, int use_large_pages)
4202 {
4203 int i;
4204 size_t maxbuf;
4205 kmem_magtype_t *mtp;
4206
4207 for (i = 0; i < sizeof (kmem_magtype) / sizeof (*mtp); i++) {
4208 char name[KMEM_CACHE_NAMELEN + 1];
4209
4210 mtp = &kmem_magtype[i];
4211 (void) sprintf(name, "kmem_magazine_%d", mtp->mt_magsize);
4212 mtp->mt_cache = kmem_cache_create(name,
4213 (mtp->mt_magsize + 1) * sizeof (void *),
4214 mtp->mt_align, NULL, NULL, NULL, NULL,
4215 kmem_msb_arena, KMC_NOHASH);
4216 }
4217
4218 kmem_slab_cache = kmem_cache_create("kmem_slab_cache",
4219 sizeof (kmem_slab_t), 0, NULL, NULL, NULL, NULL,
4220 kmem_msb_arena, KMC_NOHASH);
4221
4222 kmem_bufctl_cache = kmem_cache_create("kmem_bufctl_cache",
4223 sizeof (kmem_bufctl_t), 0, NULL, NULL, NULL, NULL,
4224 kmem_msb_arena, KMC_NOHASH);
4225
4226 kmem_bufctl_audit_cache = kmem_cache_create("kmem_bufctl_audit_cache",
4227 sizeof (kmem_bufctl_audit_t), 0, NULL, NULL, NULL, NULL,
4228 kmem_msb_arena, KMC_NOHASH);
4229
4230 if (pass == 2) {
4231 kmem_va_arena = vmem_create("kmem_va",
4232 NULL, 0, PAGESIZE,
4233 vmem_alloc, vmem_free, heap_arena,
4234 8 * PAGESIZE, VM_SLEEP);
4235
4236 if (use_large_pages) {
4237 kmem_default_arena = vmem_xcreate("kmem_default",
4238 NULL, 0, PAGESIZE,
4239 segkmem_alloc_lp, segkmem_free_lp, kmem_va_arena,
4240 0, VMC_DUMPSAFE | VM_SLEEP);
4241 } else {
4242 kmem_default_arena = vmem_create("kmem_default",
4243 NULL, 0, PAGESIZE,
4244 segkmem_alloc, segkmem_free, kmem_va_arena,
4245 0, VMC_DUMPSAFE | VM_SLEEP);
4246 }
4247
4248 /* Figure out what our maximum cache size is */
4249 maxbuf = kmem_max_cached;
4250 if (maxbuf <= KMEM_MAXBUF) {
4251 maxbuf = 0;
4252 kmem_max_cached = KMEM_MAXBUF;
4253 } else {
4254 size_t size = 0;
4255 size_t max =
4256 sizeof (kmem_big_alloc_sizes) / sizeof (int);
4257 /*
4258 * Round maxbuf up to an existing cache size. If maxbuf
4259 * is larger than the largest cache, we truncate it to
4260 * the largest cache's size.
4261 */
4262 for (i = 0; i < max; i++) {
4263 size = kmem_big_alloc_sizes[i];
4264 if (maxbuf <= size)
4265 break;
4266 }
4267 kmem_max_cached = maxbuf = size;
4268 }
4269
4270 /*
4271 * The big alloc table may not be completely overwritten, so
4272 * we clear out any stale cache pointers from the first pass.
4273 */
4274 bzero(kmem_big_alloc_table, sizeof (kmem_big_alloc_table));
4275 } else {
4276 /*
4277 * During the first pass, the kmem_alloc_* caches
4278 * are treated as metadata.
4279 */
4280 kmem_default_arena = kmem_msb_arena;
4281 maxbuf = KMEM_BIG_MAXBUF_32BIT;
4282 }
4283
4284 /*
4285 * Set up the default caches to back kmem_alloc()
4286 */
4287 kmem_alloc_caches_create(
4288 kmem_alloc_sizes, sizeof (kmem_alloc_sizes) / sizeof (int),
4289 kmem_alloc_table, KMEM_MAXBUF, KMEM_ALIGN_SHIFT);
4290
4291 kmem_alloc_caches_create(
4292 kmem_big_alloc_sizes, sizeof (kmem_big_alloc_sizes) / sizeof (int),
4293 kmem_big_alloc_table, maxbuf, KMEM_BIG_SHIFT);
4294
4295 kmem_big_alloc_table_max = maxbuf >> KMEM_BIG_SHIFT;
4296 }
4297
4298 void
4299 kmem_init(void)
4300 {
4301 kmem_cache_t *cp;
4302 int old_kmem_flags = kmem_flags;
4303 int use_large_pages = 0;
4304 size_t maxverify, minfirewall;
4305
4306 kstat_init();
4307
4308 /*
4309 * Don't do firewalled allocations if the heap is less than 1TB
4310 * (i.e. on a 32-bit kernel)
4311 * The resulting VM_NEXTFIT allocations would create too much
4312 * fragmentation in a small heap.
4313 */
4314 #if defined(_LP64)
4315 maxverify = minfirewall = PAGESIZE / 2;
4316 #else
4317 maxverify = minfirewall = ULONG_MAX;
4318 #endif
4319
4320 /* LINTED */
4321 ASSERT(sizeof (kmem_cpu_cache_t) == KMEM_CPU_CACHE_SIZE);
4322
4323 list_create(&kmem_caches, sizeof (kmem_cache_t),
4324 offsetof(kmem_cache_t, cache_link));
4325
4326 kmem_metadata_arena = vmem_create("kmem_metadata", NULL, 0, PAGESIZE,
4327 vmem_alloc, vmem_free, heap_arena, 8 * PAGESIZE,
4328 VM_SLEEP | VMC_NO_QCACHE);
4329
4330 kmem_msb_arena = vmem_create("kmem_msb", NULL, 0,
4331 PAGESIZE, segkmem_alloc, segkmem_free, kmem_metadata_arena, 0,
4332 VMC_DUMPSAFE | VM_SLEEP);
4333
4334 kmem_cache_arena = vmem_create("kmem_cache", NULL, 0, KMEM_ALIGN,
4335 segkmem_alloc, segkmem_free, kmem_metadata_arena, 0, VM_SLEEP);
4336
4337 kmem_hash_arena = vmem_create("kmem_hash", NULL, 0, KMEM_ALIGN,
4338 segkmem_alloc, segkmem_free, kmem_metadata_arena, 0, VM_SLEEP);
4339
4340 kmem_log_arena = vmem_create("kmem_log", NULL, 0, KMEM_ALIGN,
4341 segkmem_alloc, segkmem_free, heap_arena, 0, VM_SLEEP);
4342
4343 kmem_firewall_va_arena = vmem_create("kmem_firewall_va",
4344 NULL, 0, PAGESIZE,
4345 kmem_firewall_va_alloc, kmem_firewall_va_free, heap_arena,
4346 0, VM_SLEEP);
4347
4348 kmem_firewall_arena = vmem_create("kmem_firewall", NULL, 0, PAGESIZE,
4349 segkmem_alloc, segkmem_free, kmem_firewall_va_arena, 0,
4350 VMC_DUMPSAFE | VM_SLEEP);
4351
4352 /* temporary oversize arena for mod_read_system_file */
4353 kmem_oversize_arena = vmem_create("kmem_oversize", NULL, 0, PAGESIZE,
4354 segkmem_alloc, segkmem_free, heap_arena, 0, VM_SLEEP);
4355
4356 kmem_reap_interval = 15 * hz;
4357
4358 /*
4359 * Read /etc/system. This is a chicken-and-egg problem because
4360 * kmem_flags may be set in /etc/system, but mod_read_system_file()
4361 * needs to use the allocator. The simplest solution is to create
4362 * all the standard kmem caches, read /etc/system, destroy all the
4363 * caches we just created, and then create them all again in light
4364 * of the (possibly) new kmem_flags and other kmem tunables.
4365 */
4366 kmem_cache_init(1, 0);
4367
4368 mod_read_system_file(boothowto & RB_ASKNAME);
4369
4370 while ((cp = list_tail(&kmem_caches)) != NULL)
4371 kmem_cache_destroy(cp);
4372
4373 vmem_destroy(kmem_oversize_arena);
4374
4375 if (old_kmem_flags & KMF_STICKY)
4376 kmem_flags = old_kmem_flags;
4377
4378 if (!(kmem_flags & KMF_AUDIT))
4379 vmem_seg_size = offsetof(vmem_seg_t, vs_thread);
4380
4381 if (kmem_maxverify == 0)
4382 kmem_maxverify = maxverify;
4383
4384 if (kmem_minfirewall == 0)
4385 kmem_minfirewall = minfirewall;
4386
4387 /*
4388 * give segkmem a chance to figure out if we are using large pages
4389 * for the kernel heap
4390 */
4391 use_large_pages = segkmem_lpsetup();
4392
4393 /*
4394 * To protect against corruption, we keep the actual number of callers
4395 * KMF_LITE records seperate from the tunable. We arbitrarily clamp
4396 * to 16, since the overhead for small buffers quickly gets out of
4397 * hand.
4398 *
4399 * The real limit would depend on the needs of the largest KMC_NOHASH
4400 * cache.
4401 */
4402 kmem_lite_count = MIN(MAX(0, kmem_lite_pcs), 16);
4403 kmem_lite_pcs = kmem_lite_count;
4404
4405 /*
4406 * Normally, we firewall oversized allocations when possible, but
4407 * if we are using large pages for kernel memory, and we don't have
4408 * any non-LITE debugging flags set, we want to allocate oversized
4409 * buffers from large pages, and so skip the firewalling.
4410 */
4411 if (use_large_pages &&
4412 ((kmem_flags & KMF_LITE) || !(kmem_flags & KMF_DEBUG))) {
4413 kmem_oversize_arena = vmem_xcreate("kmem_oversize", NULL, 0,
4414 PAGESIZE, segkmem_alloc_lp, segkmem_free_lp, heap_arena,
4415 0, VMC_DUMPSAFE | VM_SLEEP);
4416 } else {
4417 kmem_oversize_arena = vmem_create("kmem_oversize",
4418 NULL, 0, PAGESIZE,
4419 segkmem_alloc, segkmem_free, kmem_minfirewall < ULONG_MAX?
4420 kmem_firewall_va_arena : heap_arena, 0, VMC_DUMPSAFE |
4421 VM_SLEEP);
4422 }
4423
4424 kmem_cache_init(2, use_large_pages);
4425
4426 if (kmem_flags & (KMF_AUDIT | KMF_RANDOMIZE)) {
4427 if (kmem_transaction_log_size == 0)
4428 kmem_transaction_log_size = kmem_maxavail() / 50;
4429 kmem_transaction_log = kmem_log_init(kmem_transaction_log_size);
4430 }
4431
4432 if (kmem_flags & (KMF_CONTENTS | KMF_RANDOMIZE)) {
4433 if (kmem_content_log_size == 0)
4434 kmem_content_log_size = kmem_maxavail() / 50;
4435 kmem_content_log = kmem_log_init(kmem_content_log_size);
4436 }
4437
4438 kmem_failure_log = kmem_log_init(kmem_failure_log_size);
4439
4440 kmem_slab_log = kmem_log_init(kmem_slab_log_size);
4441
4442 /*
4443 * Initialize STREAMS message caches so allocb() is available.
4444 * This allows us to initialize the logging framework (cmn_err(9F),
4445 * strlog(9F), etc) so we can start recording messages.
4446 */
4447 streams_msg_init();
4448
4449 /*
4450 * Initialize the ZSD framework in Zones so modules loaded henceforth
4451 * can register their callbacks.
4452 */
4453 zone_zsd_init();
4454
4455 log_init();
4456 taskq_init();
4457
4458 /*
4459 * Warn about invalid or dangerous values of kmem_flags.
4460 * Always warn about unsupported values.
4461 */
4462 if (((kmem_flags & ~(KMF_AUDIT | KMF_DEADBEEF | KMF_REDZONE |
4463 KMF_CONTENTS | KMF_LITE)) != 0) ||
4464 ((kmem_flags & KMF_LITE) && kmem_flags != KMF_LITE))
4465 cmn_err(CE_WARN, "kmem_flags set to unsupported value 0x%x. "
4466 "See the Solaris Tunable Parameters Reference Manual.",
4467 kmem_flags);
4468
4469 #ifdef DEBUG
4470 if ((kmem_flags & KMF_DEBUG) == 0)
4471 cmn_err(CE_NOTE, "kmem debugging disabled.");
4472 #else
4473 /*
4474 * For non-debug kernels, the only "normal" flags are 0, KMF_LITE,
4475 * KMF_REDZONE, and KMF_CONTENTS (the last because it is only enabled
4476 * if KMF_AUDIT is set). We should warn the user about the performance
4477 * penalty of KMF_AUDIT or KMF_DEADBEEF if they are set and KMF_LITE
4478 * isn't set (since that disables AUDIT).
4479 */
4480 if (!(kmem_flags & KMF_LITE) &&
4481 (kmem_flags & (KMF_AUDIT | KMF_DEADBEEF)) != 0)
4482 cmn_err(CE_WARN, "High-overhead kmem debugging features "
4483 "enabled (kmem_flags = 0x%x). Performance degradation "
4484 "and large memory overhead possible. See the Solaris "
4485 "Tunable Parameters Reference Manual.", kmem_flags);
4486 #endif /* not DEBUG */
4487
4488 kmem_cache_applyall(kmem_cache_magazine_enable, NULL, TQ_SLEEP);
4489
4490 kmem_ready = 1;
4491
4492 /*
4493 * Initialize the platform-specific aligned/DMA memory allocator.
4494 */
4495 ka_init();
4496
4497 /*
4498 * Initialize 32-bit ID cache.
4499 */
4500 id32_init();
4501
4502 /*
4503 * Initialize the networking stack so modules loaded can
4504 * register their callbacks.
4505 */
4506 netstack_init();
4507 }
4508
4509 static void
4510 kmem_move_init(void)
4511 {
4512 kmem_defrag_cache = kmem_cache_create("kmem_defrag_cache",
4513 sizeof (kmem_defrag_t), 0, NULL, NULL, NULL, NULL,
4514 kmem_msb_arena, KMC_NOHASH);
4515 kmem_move_cache = kmem_cache_create("kmem_move_cache",
4516 sizeof (kmem_move_t), 0, NULL, NULL, NULL, NULL,
4517 kmem_msb_arena, KMC_NOHASH);
4518
4519 /*
4520 * kmem guarantees that move callbacks are sequential and that even
4521 * across multiple caches no two moves ever execute simultaneously.
4522 * Move callbacks are processed on a separate taskq so that client code
4523 * does not interfere with internal maintenance tasks.
4524 */
4525 kmem_move_taskq = taskq_create_instance("kmem_move_taskq", 0, 1,
4526 minclsyspri, 100, INT_MAX, TASKQ_PREPOPULATE);
4527 }
4528
4529 void
4530 kmem_thread_init(void)
4531 {
4532 kmem_move_init();
4533 kmem_taskq = taskq_create_instance("kmem_taskq", 0, 1, minclsyspri,
4534 300, INT_MAX, TASKQ_PREPOPULATE);
4535 }
4536
4537 void
4538 kmem_mp_init(void)
4539 {
4540 mutex_enter(&cpu_lock);
4541 register_cpu_setup_func(kmem_cpu_setup, NULL);
4542 mutex_exit(&cpu_lock);
4543
4544 kmem_update_timeout(NULL);
4545
4546 taskq_mp_init();
4547 }
4548
4549 /*
4550 * Return the slab of the allocated buffer, or NULL if the buffer is not
4551 * allocated. This function may be called with a known slab address to determine
4552 * whether or not the buffer is allocated, or with a NULL slab address to obtain
4553 * an allocated buffer's slab.
4554 */
4555 static kmem_slab_t *
4556 kmem_slab_allocated(kmem_cache_t *cp, kmem_slab_t *sp, void *buf)
4557 {
4558 kmem_bufctl_t *bcp, *bufbcp;
4559
4560 ASSERT(MUTEX_HELD(&cp->cache_lock));
4561 ASSERT(sp == NULL || KMEM_SLAB_MEMBER(sp, buf));
4562
4563 if (cp->cache_flags & KMF_HASH) {
4564 for (bcp = *KMEM_HASH(cp, buf);
4565 (bcp != NULL) && (bcp->bc_addr != buf);
4566 bcp = bcp->bc_next) {
4567 continue;
4568 }
4569 ASSERT(sp != NULL && bcp != NULL ? sp == bcp->bc_slab : 1);
4570 return (bcp == NULL ? NULL : bcp->bc_slab);
4571 }
4572
4573 if (sp == NULL) {
4574 sp = KMEM_SLAB(cp, buf);
4575 }
4576 bufbcp = KMEM_BUFCTL(cp, buf);
4577 for (bcp = sp->slab_head;
4578 (bcp != NULL) && (bcp != bufbcp);
4579 bcp = bcp->bc_next) {
4580 continue;
4581 }
4582 return (bcp == NULL ? sp : NULL);
4583 }
4584
4585 static boolean_t
4586 kmem_slab_is_reclaimable(kmem_cache_t *cp, kmem_slab_t *sp, int flags)
4587 {
4588 long refcnt = sp->slab_refcnt;
4589
4590 ASSERT(cp->cache_defrag != NULL);
4591
4592 /*
4593 * For code coverage we want to be able to move an object within the
4594 * same slab (the only partial slab) even if allocating the destination
4595 * buffer resulted in a completely allocated slab.
4596 */
4597 if (flags & KMM_DEBUG) {
4598 return ((flags & KMM_DESPERATE) ||
4599 ((sp->slab_flags & KMEM_SLAB_NOMOVE) == 0));
4600 }
4601
4602 /* If we're desperate, we don't care if the client said NO. */
4603 if (flags & KMM_DESPERATE) {
4604 return (refcnt < sp->slab_chunks); /* any partial */
4605 }
4606
4607 if (sp->slab_flags & KMEM_SLAB_NOMOVE) {
4608 return (B_FALSE);
4609 }
4610
4611 if ((refcnt == 1) || kmem_move_any_partial) {
4612 return (refcnt < sp->slab_chunks);
4613 }
4614
4615 /*
4616 * The reclaim threshold is adjusted at each kmem_cache_scan() so that
4617 * slabs with a progressively higher percentage of used buffers can be
4618 * reclaimed until the cache as a whole is no longer fragmented.
4619 *
4620 * sp->slab_refcnt kmd_reclaim_numer
4621 * --------------- < ------------------
4622 * sp->slab_chunks KMEM_VOID_FRACTION
4623 */
4624 return ((refcnt * KMEM_VOID_FRACTION) <
4625 (sp->slab_chunks * cp->cache_defrag->kmd_reclaim_numer));
4626 }
4627
4628 /*
4629 * May be called from the kmem_move_taskq, from kmem_cache_move_notify_task(),
4630 * or when the buffer is freed.
4631 */
4632 static void
4633 kmem_slab_move_yes(kmem_cache_t *cp, kmem_slab_t *sp, void *from_buf)
4634 {
4635 ASSERT(MUTEX_HELD(&cp->cache_lock));
4636 ASSERT(KMEM_SLAB_MEMBER(sp, from_buf));
4637
4638 if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4639 return;
4640 }
4641
4642 if (sp->slab_flags & KMEM_SLAB_NOMOVE) {
4643 if (KMEM_SLAB_OFFSET(sp, from_buf) == sp->slab_stuck_offset) {
4644 avl_remove(&cp->cache_partial_slabs, sp);
4645 sp->slab_flags &= ~KMEM_SLAB_NOMOVE;
4646 sp->slab_stuck_offset = (uint32_t)-1;
4647 avl_add(&cp->cache_partial_slabs, sp);
4648 }
4649 } else {
4650 sp->slab_later_count = 0;
4651 sp->slab_stuck_offset = (uint32_t)-1;
4652 }
4653 }
4654
4655 static void
4656 kmem_slab_move_no(kmem_cache_t *cp, kmem_slab_t *sp, void *from_buf)
4657 {
4658 ASSERT(taskq_member(kmem_move_taskq, curthread));
4659 ASSERT(MUTEX_HELD(&cp->cache_lock));
4660 ASSERT(KMEM_SLAB_MEMBER(sp, from_buf));
4661
4662 if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4663 return;
4664 }
4665
4666 avl_remove(&cp->cache_partial_slabs, sp);
4667 sp->slab_later_count = 0;
4668 sp->slab_flags |= KMEM_SLAB_NOMOVE;
4669 sp->slab_stuck_offset = KMEM_SLAB_OFFSET(sp, from_buf);
4670 avl_add(&cp->cache_partial_slabs, sp);
4671 }
4672
4673 static void kmem_move_end(kmem_cache_t *, kmem_move_t *);
4674
4675 /*
4676 * The move callback takes two buffer addresses, the buffer to be moved, and a
4677 * newly allocated and constructed buffer selected by kmem as the destination.
4678 * It also takes the size of the buffer and an optional user argument specified
4679 * at cache creation time. kmem guarantees that the buffer to be moved has not
4680 * been unmapped by the virtual memory subsystem. Beyond that, it cannot
4681 * guarantee the present whereabouts of the buffer to be moved, so it is up to
4682 * the client to safely determine whether or not it is still using the buffer.
4683 * The client must not free either of the buffers passed to the move callback,
4684 * since kmem wants to free them directly to the slab layer. The client response
4685 * tells kmem which of the two buffers to free:
4686 *
4687 * YES kmem frees the old buffer (the move was successful)
4688 * NO kmem frees the new buffer, marks the slab of the old buffer
4689 * non-reclaimable to avoid bothering the client again
4690 * LATER kmem frees the new buffer, increments slab_later_count
4691 * DONT_KNOW kmem frees the new buffer
4692 * DONT_NEED kmem frees both the old buffer and the new buffer
4693 *
4694 * The pending callback argument now being processed contains both of the
4695 * buffers (old and new) passed to the move callback function, the slab of the
4696 * old buffer, and flags related to the move request, such as whether or not the
4697 * system was desperate for memory.
4698 *
4699 * Slabs are not freed while there is a pending callback, but instead are kept
4700 * on a deadlist, which is drained after the last callback completes. This means
4701 * that slabs are safe to access until kmem_move_end(), no matter how many of
4702 * their buffers have been freed. Once slab_refcnt reaches zero, it stays at
4703 * zero for as long as the slab remains on the deadlist and until the slab is
4704 * freed.
4705 */
4706 static void
4707 kmem_move_buffer(kmem_move_t *callback)
4708 {
4709 kmem_cbrc_t response;
4710 kmem_slab_t *sp = callback->kmm_from_slab;
4711 kmem_cache_t *cp = sp->slab_cache;
4712 boolean_t free_on_slab;
4713
4714 ASSERT(taskq_member(kmem_move_taskq, curthread));
4715 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4716 ASSERT(KMEM_SLAB_MEMBER(sp, callback->kmm_from_buf));
4717
4718 /*
4719 * The number of allocated buffers on the slab may have changed since we
4720 * last checked the slab's reclaimability (when the pending move was
4721 * enqueued), or the client may have responded NO when asked to move
4722 * another buffer on the same slab.
4723 */
4724 if (!kmem_slab_is_reclaimable(cp, sp, callback->kmm_flags)) {
4725 kmem_slab_free(cp, callback->kmm_to_buf);
4726 kmem_move_end(cp, callback);
4727 return;
4728 }
4729
4730 /*
4731 * Checking the slab layer is easy, so we might as well do that here
4732 * in case we can avoid bothering the client.
4733 */
4734 mutex_enter(&cp->cache_lock);
4735 free_on_slab = (kmem_slab_allocated(cp, sp,
4736 callback->kmm_from_buf) == NULL);
4737 mutex_exit(&cp->cache_lock);
4738
4739 if (free_on_slab) {
4740 kmem_slab_free(cp, callback->kmm_to_buf);
4741 kmem_move_end(cp, callback);
4742 return;
4743 }
4744
4745 if (cp->cache_flags & KMF_BUFTAG) {
4746 /*
4747 * Make kmem_cache_alloc_debug() apply the constructor for us.
4748 */
4749 if (kmem_cache_alloc_debug(cp, callback->kmm_to_buf,
4750 KM_NOSLEEP, 1, caller()) != 0) {
4751 kmem_move_end(cp, callback);
4752 return;
4753 }
4754 } else if (cp->cache_constructor != NULL &&
4755 cp->cache_constructor(callback->kmm_to_buf, cp->cache_private,
4756 KM_NOSLEEP) != 0) {
4757 atomic_inc_64(&cp->cache_alloc_fail);
4758 kmem_slab_free(cp, callback->kmm_to_buf);
4759 kmem_move_end(cp, callback);
4760 return;
4761 }
4762
4763 cp->cache_defrag->kmd_callbacks++;
4764 cp->cache_defrag->kmd_thread = curthread;
4765 cp->cache_defrag->kmd_from_buf = callback->kmm_from_buf;
4766 cp->cache_defrag->kmd_to_buf = callback->kmm_to_buf;
4767 DTRACE_PROBE2(kmem__move__start, kmem_cache_t *, cp, kmem_move_t *,
4768 callback);
4769
4770 response = cp->cache_move(callback->kmm_from_buf,
4771 callback->kmm_to_buf, cp->cache_bufsize, cp->cache_private);
4772
4773 DTRACE_PROBE3(kmem__move__end, kmem_cache_t *, cp, kmem_move_t *,
4774 callback, kmem_cbrc_t, response);
4775 cp->cache_defrag->kmd_thread = NULL;
4776 cp->cache_defrag->kmd_from_buf = NULL;
4777 cp->cache_defrag->kmd_to_buf = NULL;
4778
4779 if (response == KMEM_CBRC_YES) {
4780 cp->cache_defrag->kmd_yes++;
4781 kmem_slab_free_constructed(cp, callback->kmm_from_buf, B_FALSE);
4782 /* slab safe to access until kmem_move_end() */
4783 if (sp->slab_refcnt == 0)
4784 cp->cache_defrag->kmd_slabs_freed++;
4785 mutex_enter(&cp->cache_lock);
4786 kmem_slab_move_yes(cp, sp, callback->kmm_from_buf);
4787 mutex_exit(&cp->cache_lock);
4788 kmem_move_end(cp, callback);
4789 return;
4790 }
4791
4792 switch (response) {
4793 case KMEM_CBRC_NO:
4794 cp->cache_defrag->kmd_no++;
4795 mutex_enter(&cp->cache_lock);
4796 kmem_slab_move_no(cp, sp, callback->kmm_from_buf);
4797 mutex_exit(&cp->cache_lock);
4798 break;
4799 case KMEM_CBRC_LATER:
4800 cp->cache_defrag->kmd_later++;
4801 mutex_enter(&cp->cache_lock);
4802 if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4803 mutex_exit(&cp->cache_lock);
4804 break;
4805 }
4806
4807 if (++sp->slab_later_count >= KMEM_DISBELIEF) {
4808 kmem_slab_move_no(cp, sp, callback->kmm_from_buf);
4809 } else if (!(sp->slab_flags & KMEM_SLAB_NOMOVE)) {
4810 sp->slab_stuck_offset = KMEM_SLAB_OFFSET(sp,
4811 callback->kmm_from_buf);
4812 }
4813 mutex_exit(&cp->cache_lock);
4814 break;
4815 case KMEM_CBRC_DONT_NEED:
4816 cp->cache_defrag->kmd_dont_need++;
4817 kmem_slab_free_constructed(cp, callback->kmm_from_buf, B_FALSE);
4818 if (sp->slab_refcnt == 0)
4819 cp->cache_defrag->kmd_slabs_freed++;
4820 mutex_enter(&cp->cache_lock);
4821 kmem_slab_move_yes(cp, sp, callback->kmm_from_buf);
4822 mutex_exit(&cp->cache_lock);
4823 break;
4824 case KMEM_CBRC_DONT_KNOW:
4825 /*
4826 * If we don't know if we can move this buffer or not, we'll
4827 * just assume that we can't: if the buffer is in fact free,
4828 * then it is sitting in one of the per-CPU magazines or in
4829 * a full magazine in the depot layer. Either way, because
4830 * defrag is induced in the same logic that reaps a cache,
4831 * it's likely that full magazines will be returned to the
4832 * system soon (thereby accomplishing what we're trying to
4833 * accomplish here: return those magazines to their slabs).
4834 * Given this, any work that we might do now to locate a buffer
4835 * in a magazine is wasted (and expensive!) work; we bump
4836 * a counter in this case and otherwise assume that we can't
4837 * move it.
4838 */
4839 cp->cache_defrag->kmd_dont_know++;
4840 break;
4841 default:
4842 panic("'%s' (%p) unexpected move callback response %d\n",
4843 cp->cache_name, (void *)cp, response);
4844 }
4845
4846 kmem_slab_free_constructed(cp, callback->kmm_to_buf, B_FALSE);
4847 kmem_move_end(cp, callback);
4848 }
4849
4850 /* Return B_FALSE if there is insufficient memory for the move request. */
4851 static boolean_t
4852 kmem_move_begin(kmem_cache_t *cp, kmem_slab_t *sp, void *buf, int flags)
4853 {
4854 void *to_buf;
4855 avl_index_t index;
4856 kmem_move_t *callback, *pending;
4857 ulong_t n;
4858
4859 ASSERT(taskq_member(kmem_taskq, curthread));
4860 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4861 ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
4862
4863 callback = kmem_cache_alloc(kmem_move_cache, KM_NOSLEEP);
4864
4865 if (callback == NULL)
4866 return (B_FALSE);
4867
4868 callback->kmm_from_slab = sp;
4869 callback->kmm_from_buf = buf;
4870 callback->kmm_flags = flags;
4871
4872 mutex_enter(&cp->cache_lock);
4873
4874 n = avl_numnodes(&cp->cache_partial_slabs);
4875 if ((n == 0) || ((n == 1) && !(flags & KMM_DEBUG))) {
4876 mutex_exit(&cp->cache_lock);
4877 kmem_cache_free(kmem_move_cache, callback);
4878 return (B_TRUE); /* there is no need for the move request */
4879 }
4880
4881 pending = avl_find(&cp->cache_defrag->kmd_moves_pending, buf, &index);
4882 if (pending != NULL) {
4883 /*
4884 * If the move is already pending and we're desperate now,
4885 * update the move flags.
4886 */
4887 if (flags & KMM_DESPERATE) {
4888 pending->kmm_flags |= KMM_DESPERATE;
4889 }
4890 mutex_exit(&cp->cache_lock);
4891 kmem_cache_free(kmem_move_cache, callback);
4892 return (B_TRUE);
4893 }
4894
4895 to_buf = kmem_slab_alloc_impl(cp, avl_first(&cp->cache_partial_slabs),
4896 B_FALSE);
4897 callback->kmm_to_buf = to_buf;
4898 avl_insert(&cp->cache_defrag->kmd_moves_pending, callback, index);
4899
4900 mutex_exit(&cp->cache_lock);
4901
4902 if (!taskq_dispatch(kmem_move_taskq, (task_func_t *)kmem_move_buffer,
4903 callback, TQ_NOSLEEP)) {
4904 mutex_enter(&cp->cache_lock);
4905 avl_remove(&cp->cache_defrag->kmd_moves_pending, callback);
4906 mutex_exit(&cp->cache_lock);
4907 kmem_slab_free(cp, to_buf);
4908 kmem_cache_free(kmem_move_cache, callback);
4909 return (B_FALSE);
4910 }
4911
4912 return (B_TRUE);
4913 }
4914
4915 static void
4916 kmem_move_end(kmem_cache_t *cp, kmem_move_t *callback)
4917 {
4918 avl_index_t index;
4919
4920 ASSERT(cp->cache_defrag != NULL);
4921 ASSERT(taskq_member(kmem_move_taskq, curthread));
4922 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4923
4924 mutex_enter(&cp->cache_lock);
4925 VERIFY(avl_find(&cp->cache_defrag->kmd_moves_pending,
4926 callback->kmm_from_buf, &index) != NULL);
4927 avl_remove(&cp->cache_defrag->kmd_moves_pending, callback);
4928 if (avl_is_empty(&cp->cache_defrag->kmd_moves_pending)) {
4929 list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
4930 kmem_slab_t *sp;
4931
4932 /*
4933 * The last pending move completed. Release all slabs from the
4934 * front of the dead list except for any slab at the tail that
4935 * needs to be released from the context of kmem_move_buffers().
4936 * kmem deferred unmapping the buffers on these slabs in order
4937 * to guarantee that buffers passed to the move callback have
4938 * been touched only by kmem or by the client itself.
4939 */
4940 while ((sp = list_remove_head(deadlist)) != NULL) {
4941 if (sp->slab_flags & KMEM_SLAB_MOVE_PENDING) {
4942 list_insert_tail(deadlist, sp);
4943 break;
4944 }
4945 cp->cache_defrag->kmd_deadcount--;
4946 cp->cache_slab_destroy++;
4947 mutex_exit(&cp->cache_lock);
4948 kmem_slab_destroy(cp, sp);
4949 mutex_enter(&cp->cache_lock);
4950 }
4951 }
4952 mutex_exit(&cp->cache_lock);
4953 kmem_cache_free(kmem_move_cache, callback);
4954 }
4955
4956 /*
4957 * Move buffers from least used slabs first by scanning backwards from the end
4958 * of the partial slab list. Scan at most max_scan candidate slabs and move
4959 * buffers from at most max_slabs slabs (0 for all partial slabs in both cases).
4960 * If desperate to reclaim memory, move buffers from any partial slab, otherwise
4961 * skip slabs with a ratio of allocated buffers at or above the current
4962 * threshold. Return the number of unskipped slabs (at most max_slabs, -1 if the
4963 * scan is aborted) so that the caller can adjust the reclaimability threshold
4964 * depending on how many reclaimable slabs it finds.
4965 *
4966 * kmem_move_buffers() drops and reacquires cache_lock every time it issues a
4967 * move request, since it is not valid for kmem_move_begin() to call
4968 * kmem_cache_alloc() or taskq_dispatch() with cache_lock held.
4969 */
4970 static int
4971 kmem_move_buffers(kmem_cache_t *cp, size_t max_scan, size_t max_slabs,
4972 int flags)
4973 {
4974 kmem_slab_t *sp;
4975 void *buf;
4976 int i, j; /* slab index, buffer index */
4977 int s; /* reclaimable slabs */
4978 int b; /* allocated (movable) buffers on reclaimable slab */
4979 boolean_t success;
4980 int refcnt;
4981 int nomove;
4982
4983 ASSERT(taskq_member(kmem_taskq, curthread));
4984 ASSERT(MUTEX_HELD(&cp->cache_lock));
4985 ASSERT(kmem_move_cache != NULL);
4986 ASSERT(cp->cache_move != NULL && cp->cache_defrag != NULL);
4987 ASSERT((flags & KMM_DEBUG) ? !avl_is_empty(&cp->cache_partial_slabs) :
4988 avl_numnodes(&cp->cache_partial_slabs) > 1);
4989
4990 if (kmem_move_blocked) {
4991 return (0);
4992 }
4993
4994 if (kmem_move_fulltilt) {
4995 flags |= KMM_DESPERATE;
4996 }
4997
4998 if (max_scan == 0 || (flags & KMM_DESPERATE)) {
4999 /*
5000 * Scan as many slabs as needed to find the desired number of
5001 * candidate slabs.
5002 */
5003 max_scan = (size_t)-1;
5004 }
5005
5006 if (max_slabs == 0 || (flags & KMM_DESPERATE)) {
5007 /* Find as many candidate slabs as possible. */
5008 max_slabs = (size_t)-1;
5009 }
5010
5011 sp = avl_last(&cp->cache_partial_slabs);
5012 ASSERT(KMEM_SLAB_IS_PARTIAL(sp));
5013 for (i = 0, s = 0; (i < max_scan) && (s < max_slabs) && (sp != NULL) &&
5014 ((sp != avl_first(&cp->cache_partial_slabs)) ||
5015 (flags & KMM_DEBUG));
5016 sp = AVL_PREV(&cp->cache_partial_slabs, sp), i++) {
5017
5018 if (!kmem_slab_is_reclaimable(cp, sp, flags)) {
5019 continue;
5020 }
5021 s++;
5022
5023 /* Look for allocated buffers to move. */
5024 for (j = 0, b = 0, buf = sp->slab_base;
5025 (j < sp->slab_chunks) && (b < sp->slab_refcnt);
5026 buf = (((char *)buf) + cp->cache_chunksize), j++) {
5027
5028 if (kmem_slab_allocated(cp, sp, buf) == NULL) {
5029 continue;
5030 }
5031
5032 b++;
5033
5034 /*
5035 * Prevent the slab from being destroyed while we drop
5036 * cache_lock and while the pending move is not yet
5037 * registered. Flag the pending move while
5038 * kmd_moves_pending may still be empty, since we can't
5039 * yet rely on a non-zero pending move count to prevent
5040 * the slab from being destroyed.
5041 */
5042 ASSERT(!(sp->slab_flags & KMEM_SLAB_MOVE_PENDING));
5043 sp->slab_flags |= KMEM_SLAB_MOVE_PENDING;
5044 /*
5045 * Recheck refcnt and nomove after reacquiring the lock,
5046 * since these control the order of partial slabs, and
5047 * we want to know if we can pick up the scan where we
5048 * left off.
5049 */
5050 refcnt = sp->slab_refcnt;
5051 nomove = (sp->slab_flags & KMEM_SLAB_NOMOVE);
5052 mutex_exit(&cp->cache_lock);
5053
5054 success = kmem_move_begin(cp, sp, buf, flags);
5055
5056 /*
5057 * Now, before the lock is reacquired, kmem could
5058 * process all pending move requests and purge the
5059 * deadlist, so that upon reacquiring the lock, sp has
5060 * been remapped. Or, the client may free all the
5061 * objects on the slab while the pending moves are still
5062 * on the taskq. Therefore, the KMEM_SLAB_MOVE_PENDING
5063 * flag causes the slab to be put at the end of the
5064 * deadlist and prevents it from being destroyed, since
5065 * we plan to destroy it here after reacquiring the
5066 * lock.
5067 */
5068 mutex_enter(&cp->cache_lock);
5069 ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
5070 sp->slab_flags &= ~KMEM_SLAB_MOVE_PENDING;
5071
5072 if (sp->slab_refcnt == 0) {
5073 list_t *deadlist =
5074 &cp->cache_defrag->kmd_deadlist;
5075 list_remove(deadlist, sp);
5076
5077 if (!avl_is_empty(
5078 &cp->cache_defrag->kmd_moves_pending)) {
5079 /*
5080 * A pending move makes it unsafe to
5081 * destroy the slab, because even though
5082 * the move is no longer needed, the
5083 * context where that is determined
5084 * requires the slab to exist.
5085 * Fortunately, a pending move also
5086 * means we don't need to destroy the
5087 * slab here, since it will get
5088 * destroyed along with any other slabs
5089 * on the deadlist after the last
5090 * pending move completes.
5091 */
5092 list_insert_head(deadlist, sp);
5093 return (-1);
5094 }
5095
5096 /*
5097 * Destroy the slab now if it was completely
5098 * freed while we dropped cache_lock and there
5099 * are no pending moves. Since slab_refcnt
5100 * cannot change once it reaches zero, no new
5101 * pending moves from that slab are possible.
5102 */
5103 cp->cache_defrag->kmd_deadcount--;
5104 cp->cache_slab_destroy++;
5105 mutex_exit(&cp->cache_lock);
5106 kmem_slab_destroy(cp, sp);
5107 mutex_enter(&cp->cache_lock);
5108 /*
5109 * Since we can't pick up the scan where we left
5110 * off, abort the scan and say nothing about the
5111 * number of reclaimable slabs.
5112 */
5113 return (-1);
5114 }
5115
5116 if (!success) {
5117 /*
5118 * Abort the scan if there is not enough memory
5119 * for the request and say nothing about the
5120 * number of reclaimable slabs.
5121 */
5122 return (-1);
5123 }
5124
5125 /*
5126 * The slab's position changed while the lock was
5127 * dropped, so we don't know where we are in the
5128 * sequence any more.
5129 */
5130 if (sp->slab_refcnt != refcnt) {
5131 /*
5132 * If this is a KMM_DEBUG move, the slab_refcnt
5133 * may have changed because we allocated a
5134 * destination buffer on the same slab. In that
5135 * case, we're not interested in counting it.
5136 */
5137 return (-1);
5138 }
5139 if ((sp->slab_flags & KMEM_SLAB_NOMOVE) != nomove)
5140 return (-1);
5141
5142 /*
5143 * Generating a move request allocates a destination
5144 * buffer from the slab layer, bumping the first partial
5145 * slab if it is completely allocated. If the current
5146 * slab becomes the first partial slab as a result, we
5147 * can't continue to scan backwards.
5148 *
5149 * If this is a KMM_DEBUG move and we allocated the
5150 * destination buffer from the last partial slab, then
5151 * the buffer we're moving is on the same slab and our
5152 * slab_refcnt has changed, causing us to return before
5153 * reaching here if there are no partial slabs left.
5154 */
5155 ASSERT(!avl_is_empty(&cp->cache_partial_slabs));
5156 if (sp == avl_first(&cp->cache_partial_slabs)) {
5157 /*
5158 * We're not interested in a second KMM_DEBUG
5159 * move.
5160 */
5161 goto end_scan;
5162 }
5163 }
5164 }
5165 end_scan:
5166
5167 return (s);
5168 }
5169
5170 typedef struct kmem_move_notify_args {
5171 kmem_cache_t *kmna_cache;
5172 void *kmna_buf;
5173 } kmem_move_notify_args_t;
5174
5175 static void
5176 kmem_cache_move_notify_task(void *arg)
5177 {
5178 kmem_move_notify_args_t *args = arg;
5179 kmem_cache_t *cp = args->kmna_cache;
5180 void *buf = args->kmna_buf;
5181 kmem_slab_t *sp;
5182
5183 ASSERT(taskq_member(kmem_taskq, curthread));
5184 ASSERT(list_link_active(&cp->cache_link));
5185
5186 kmem_free(args, sizeof (kmem_move_notify_args_t));
5187 mutex_enter(&cp->cache_lock);
5188 sp = kmem_slab_allocated(cp, NULL, buf);
5189
5190 /* Ignore the notification if the buffer is no longer allocated. */
5191 if (sp == NULL) {
5192 mutex_exit(&cp->cache_lock);
5193 return;
5194 }
5195
5196 /* Ignore the notification if there's no reason to move the buffer. */
5197 if (avl_numnodes(&cp->cache_partial_slabs) > 1) {
5198 /*
5199 * So far the notification is not ignored. Ignore the
5200 * notification if the slab is not marked by an earlier refusal
5201 * to move a buffer.
5202 */
5203 if (!(sp->slab_flags & KMEM_SLAB_NOMOVE) &&
5204 (sp->slab_later_count == 0)) {
5205 mutex_exit(&cp->cache_lock);
5206 return;
5207 }
5208
5209 kmem_slab_move_yes(cp, sp, buf);
5210 ASSERT(!(sp->slab_flags & KMEM_SLAB_MOVE_PENDING));
5211 sp->slab_flags |= KMEM_SLAB_MOVE_PENDING;
5212 mutex_exit(&cp->cache_lock);
5213 /* see kmem_move_buffers() about dropping the lock */
5214 (void) kmem_move_begin(cp, sp, buf, KMM_NOTIFY);
5215 mutex_enter(&cp->cache_lock);
5216 ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
5217 sp->slab_flags &= ~KMEM_SLAB_MOVE_PENDING;
5218 if (sp->slab_refcnt == 0) {
5219 list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
5220 list_remove(deadlist, sp);
5221
5222 if (!avl_is_empty(
5223 &cp->cache_defrag->kmd_moves_pending)) {
5224 list_insert_head(deadlist, sp);
5225 mutex_exit(&cp->cache_lock);
5226 return;
5227 }
5228
5229 cp->cache_defrag->kmd_deadcount--;
5230 cp->cache_slab_destroy++;
5231 mutex_exit(&cp->cache_lock);
5232 kmem_slab_destroy(cp, sp);
5233 return;
5234 }
5235 } else {
5236 kmem_slab_move_yes(cp, sp, buf);
5237 }
5238 mutex_exit(&cp->cache_lock);
5239 }
5240
5241 void
5242 kmem_cache_move_notify(kmem_cache_t *cp, void *buf)
5243 {
5244 kmem_move_notify_args_t *args;
5245
5246 args = kmem_alloc(sizeof (kmem_move_notify_args_t), KM_NOSLEEP);
5247 if (args != NULL) {
5248 args->kmna_cache = cp;
5249 args->kmna_buf = buf;
5250 if (!taskq_dispatch(kmem_taskq,
5251 (task_func_t *)kmem_cache_move_notify_task, args,
5252 TQ_NOSLEEP))
5253 kmem_free(args, sizeof (kmem_move_notify_args_t));
5254 }
5255 }
5256
5257 static void
5258 kmem_cache_defrag(kmem_cache_t *cp)
5259 {
5260 size_t n;
5261
5262 ASSERT(cp->cache_defrag != NULL);
5263
5264 mutex_enter(&cp->cache_lock);
5265 n = avl_numnodes(&cp->cache_partial_slabs);
5266 if (n > 1) {
5267 /* kmem_move_buffers() drops and reacquires cache_lock */
5268 cp->cache_defrag->kmd_defrags++;
5269 (void) kmem_move_buffers(cp, n, 0, KMM_DESPERATE);
5270 }
5271 mutex_exit(&cp->cache_lock);
5272 }
5273
5274 /* Is this cache above the fragmentation threshold? */
5275 static boolean_t
5276 kmem_cache_frag_threshold(kmem_cache_t *cp, uint64_t nfree)
5277 {
5278 /*
5279 * nfree kmem_frag_numer
5280 * ------------------ > ---------------
5281 * cp->cache_buftotal kmem_frag_denom
5282 */
5283 return ((nfree * kmem_frag_denom) >
5284 (cp->cache_buftotal * kmem_frag_numer));
5285 }
5286
5287 static boolean_t
5288 kmem_cache_is_fragmented(kmem_cache_t *cp, boolean_t *doreap)
5289 {
5290 boolean_t fragmented;
5291 uint64_t nfree;
5292
5293 ASSERT(MUTEX_HELD(&cp->cache_lock));
5294 *doreap = B_FALSE;
5295
5296 if (kmem_move_fulltilt) {
5297 if (avl_numnodes(&cp->cache_partial_slabs) > 1) {
5298 return (B_TRUE);
5299 }
5300 } else {
5301 if ((cp->cache_complete_slab_count + avl_numnodes(
5302 &cp->cache_partial_slabs)) < kmem_frag_minslabs) {
5303 return (B_FALSE);
5304 }
5305 }
5306
5307 nfree = cp->cache_bufslab;
5308 fragmented = ((avl_numnodes(&cp->cache_partial_slabs) > 1) &&
5309 kmem_cache_frag_threshold(cp, nfree));
5310
5311 /*
5312 * Free buffers in the magazine layer appear allocated from the point of
5313 * view of the slab layer. We want to know if the slab layer would
5314 * appear fragmented if we included free buffers from magazines that
5315 * have fallen out of the working set.
5316 */
5317 if (!fragmented) {
5318 long reap;
5319
5320 mutex_enter(&cp->cache_depot_lock);
5321 reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
5322 reap = MIN(reap, cp->cache_full.ml_total);
5323 mutex_exit(&cp->cache_depot_lock);
5324
5325 nfree += ((uint64_t)reap * cp->cache_magtype->mt_magsize);
5326 if (kmem_cache_frag_threshold(cp, nfree)) {
5327 *doreap = B_TRUE;
5328 }
5329 }
5330
5331 return (fragmented);
5332 }
5333
5334 /* Called periodically from kmem_taskq */
5335 static void
5336 kmem_cache_scan(kmem_cache_t *cp)
5337 {
5338 boolean_t reap = B_FALSE;
5339 kmem_defrag_t *kmd;
5340
5341 ASSERT(taskq_member(kmem_taskq, curthread));
5342
5343 mutex_enter(&cp->cache_lock);
5344
5345 kmd = cp->cache_defrag;
5346 if (kmd->kmd_consolidate > 0) {
5347 kmd->kmd_consolidate--;
5348 mutex_exit(&cp->cache_lock);
5349 kmem_cache_reap(cp);
5350 return;
5351 }
5352
5353 if (kmem_cache_is_fragmented(cp, &reap)) {
5354 size_t slabs_found;
5355
5356 /*
5357 * Consolidate reclaimable slabs from the end of the partial
5358 * slab list (scan at most kmem_reclaim_scan_range slabs to find
5359 * reclaimable slabs). Keep track of how many candidate slabs we
5360 * looked for and how many we actually found so we can adjust
5361 * the definition of a candidate slab if we're having trouble
5362 * finding them.
5363 *
5364 * kmem_move_buffers() drops and reacquires cache_lock.
5365 */
5366 kmd->kmd_scans++;
5367 slabs_found = kmem_move_buffers(cp, kmem_reclaim_scan_range,
5368 kmem_reclaim_max_slabs, 0);
5369 if (slabs_found >= 0) {
5370 kmd->kmd_slabs_sought += kmem_reclaim_max_slabs;
5371 kmd->kmd_slabs_found += slabs_found;
5372 }
5373
5374 if (++kmd->kmd_tries >= kmem_reclaim_scan_range) {
5375 kmd->kmd_tries = 0;
5376
5377 /*
5378 * If we had difficulty finding candidate slabs in
5379 * previous scans, adjust the threshold so that
5380 * candidates are easier to find.
5381 */
5382 if (kmd->kmd_slabs_found == kmd->kmd_slabs_sought) {
5383 kmem_adjust_reclaim_threshold(kmd, -1);
5384 } else if ((kmd->kmd_slabs_found * 2) <
5385 kmd->kmd_slabs_sought) {
5386 kmem_adjust_reclaim_threshold(kmd, 1);
5387 }
5388 kmd->kmd_slabs_sought = 0;
5389 kmd->kmd_slabs_found = 0;
5390 }
5391 } else {
5392 kmem_reset_reclaim_threshold(cp->cache_defrag);
5393 #ifdef DEBUG
5394 if (!avl_is_empty(&cp->cache_partial_slabs)) {
5395 /*
5396 * In a debug kernel we want the consolidator to
5397 * run occasionally even when there is plenty of
5398 * memory.
5399 */
5400 uint16_t debug_rand;
5401
5402 (void) random_get_bytes((uint8_t *)&debug_rand, 2);
5403 if (!kmem_move_noreap &&
5404 ((debug_rand % kmem_mtb_reap) == 0)) {
5405 mutex_exit(&cp->cache_lock);
5406 kmem_cache_reap(cp);
5407 return;
5408 } else if ((debug_rand % kmem_mtb_move) == 0) {
5409 kmd->kmd_scans++;
5410 (void) kmem_move_buffers(cp,
5411 kmem_reclaim_scan_range, 1, KMM_DEBUG);
5412 }
5413 }
5414 #endif /* DEBUG */
5415 }
5416
5417 mutex_exit(&cp->cache_lock);
5418
5419 if (reap)
5420 kmem_depot_ws_reap(cp);
5421 }