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21 /*
22 * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
23 * Copyright 2015 Nexenta Systems, Inc. All rights reserved.
24 */
25
26 /*
27 * Kernel memory allocator, as described in the following two papers and a
28 * statement about the consolidator:
29 *
30 * Jeff Bonwick,
31 * The Slab Allocator: An Object-Caching Kernel Memory Allocator.
32 * Proceedings of the Summer 1994 Usenix Conference.
33 * Available as /shared/sac/PSARC/1994/028/materials/kmem.pdf.
34 *
35 * Jeff Bonwick and Jonathan Adams,
36 * Magazines and vmem: Extending the Slab Allocator to Many CPUs and
37 * Arbitrary Resources.
38 * Proceedings of the 2001 Usenix Conference.
39 * Available as /shared/sac/PSARC/2000/550/materials/vmem.pdf.
40 *
41 * kmem Slab Consolidator Big Theory Statement:
42 *
43 * 1. Motivation
44 *
45 * As stated in Bonwick94, slabs provide the following advantages over other
46 * allocation structures in terms of memory fragmentation:
47 *
48 * - Internal fragmentation (per-buffer wasted space) is minimal.
49 * - Severe external fragmentation (unused buffers on the free list) is
50 * unlikely.
51 *
52 * Segregating objects by size eliminates one source of external fragmentation,
53 * and according to Bonwick:
54 *
55 * The other reason that slabs reduce external fragmentation is that all
56 * objects in a slab are of the same type, so they have the same lifetime
57 * distribution. The resulting segregation of short-lived and long-lived
58 * objects at slab granularity reduces the likelihood of an entire page being
59 * held hostage due to a single long-lived allocation [Barrett93, Hanson90].
60 *
61 * While unlikely, severe external fragmentation remains possible. Clients that
62 * allocate both short- and long-lived objects from the same cache cannot
63 * anticipate the distribution of long-lived objects within the allocator's slab
64 * implementation. Even a small percentage of long-lived objects distributed
65 * randomly across many slabs can lead to a worst case scenario where the client
66 * frees the majority of its objects and the system gets back almost none of the
67 * slabs. Despite the client doing what it reasonably can to help the system
68 * reclaim memory, the allocator cannot shake free enough slabs because of
69 * lonely allocations stubbornly hanging on. Although the allocator is in a
70 * position to diagnose the fragmentation, there is nothing that the allocator
71 * by itself can do about it. It only takes a single allocated object to prevent
72 * an entire slab from being reclaimed, and any object handed out by
73 * kmem_cache_alloc() is by definition in the client's control. Conversely,
74 * although the client is in a position to move a long-lived object, it has no
75 * way of knowing if the object is causing fragmentation, and if so, where to
76 * move it. A solution necessarily requires further cooperation between the
77 * allocator and the client.
78 *
79 * 2. Move Callback
80 *
81 * The kmem slab consolidator therefore adds a move callback to the
82 * allocator/client interface, improving worst-case external fragmentation in
83 * kmem caches that supply a function to move objects from one memory location
84 * to another. In a situation of low memory kmem attempts to consolidate all of
85 * a cache's slabs at once; otherwise it works slowly to bring external
86 * fragmentation within the 1/8 limit guaranteed for internal fragmentation,
87 * thereby helping to avoid a low memory situation in the future.
88 *
89 * The callback has the following signature:
90 *
91 * kmem_cbrc_t move(void *old, void *new, size_t size, void *user_arg)
92 *
93 * It supplies the kmem client with two addresses: the allocated object that
94 * kmem wants to move and a buffer selected by kmem for the client to use as the
95 * copy destination. The callback is kmem's way of saying "Please get off of
96 * this buffer and use this one instead." kmem knows where it wants to move the
97 * object in order to best reduce fragmentation. All the client needs to know
98 * about the second argument (void *new) is that it is an allocated, constructed
99 * object ready to take the contents of the old object. When the move function
100 * is called, the system is likely to be low on memory, and the new object
101 * spares the client from having to worry about allocating memory for the
102 * requested move. The third argument supplies the size of the object, in case a
103 * single move function handles multiple caches whose objects differ only in
104 * size (such as zio_buf_512, zio_buf_1024, etc). Finally, the same optional
105 * user argument passed to the constructor, destructor, and reclaim functions is
106 * also passed to the move callback.
107 *
108 * 2.1 Setting the Move Callback
109 *
110 * The client sets the move callback after creating the cache and before
111 * allocating from it:
112 *
113 * object_cache = kmem_cache_create(...);
114 * kmem_cache_set_move(object_cache, object_move);
115 *
116 * 2.2 Move Callback Return Values
117 *
118 * Only the client knows about its own data and when is a good time to move it.
119 * The client is cooperating with kmem to return unused memory to the system,
120 * and kmem respectfully accepts this help at the client's convenience. When
121 * asked to move an object, the client can respond with any of the following:
122 *
123 * typedef enum kmem_cbrc {
124 * KMEM_CBRC_YES,
125 * KMEM_CBRC_NO,
126 * KMEM_CBRC_LATER,
127 * KMEM_CBRC_DONT_NEED,
128 * KMEM_CBRC_DONT_KNOW
129 * } kmem_cbrc_t;
130 *
131 * The client must not explicitly kmem_cache_free() either of the objects passed
132 * to the callback, since kmem wants to free them directly to the slab layer
133 * (bypassing the per-CPU magazine layer). The response tells kmem which of the
134 * objects to free:
135 *
136 * YES: (Did it) The client moved the object, so kmem frees the old one.
137 * NO: (Never) The client refused, so kmem frees the new object (the
138 * unused copy destination). kmem also marks the slab of the old
139 * object so as not to bother the client with further callbacks for
140 * that object as long as the slab remains on the partial slab list.
141 * (The system won't be getting the slab back as long as the
142 * immovable object holds it hostage, so there's no point in moving
143 * any of its objects.)
144 * LATER: The client is using the object and cannot move it now, so kmem
145 * frees the new object (the unused copy destination). kmem still
146 * attempts to move other objects off the slab, since it expects to
147 * succeed in clearing the slab in a later callback. The client
148 * should use LATER instead of NO if the object is likely to become
149 * movable very soon.
150 * DONT_NEED: The client no longer needs the object, so kmem frees the old along
151 * with the new object (the unused copy destination). This response
152 * is the client's opportunity to be a model citizen and give back as
153 * much as it can.
154 * DONT_KNOW: The client does not know about the object because
155 * a) the client has just allocated the object and not yet put it
156 * wherever it expects to find known objects
157 * b) the client has removed the object from wherever it expects to
158 * find known objects and is about to free it, or
159 * c) the client has freed the object.
160 * In all these cases (a, b, and c) kmem frees the new object (the
161 * unused copy destination) and searches for the old object in the
162 * magazine layer. If found, the object is removed from the magazine
163 * layer and freed to the slab layer so it will no longer hold the
164 * slab hostage.
165 *
166 * 2.3 Object States
167 *
168 * Neither kmem nor the client can be assumed to know the object's whereabouts
169 * at the time of the callback. An object belonging to a kmem cache may be in
170 * any of the following states:
171 *
172 * 1. Uninitialized on the slab
173 * 2. Allocated from the slab but not constructed (still uninitialized)
174 * 3. Allocated from the slab, constructed, but not yet ready for business
175 * (not in a valid state for the move callback)
176 * 4. In use (valid and known to the client)
177 * 5. About to be freed (no longer in a valid state for the move callback)
178 * 6. Freed to a magazine (still constructed)
179 * 7. Allocated from a magazine, not yet ready for business (not in a valid
180 * state for the move callback), and about to return to state #4
181 * 8. Deconstructed on a magazine that is about to be freed
182 * 9. Freed to the slab
183 *
184 * Since the move callback may be called at any time while the object is in any
185 * of the above states (except state #1), the client needs a safe way to
186 * determine whether or not it knows about the object. Specifically, the client
187 * needs to know whether or not the object is in state #4, the only state in
188 * which a move is valid. If the object is in any other state, the client should
189 * immediately return KMEM_CBRC_DONT_KNOW, since it is unsafe to access any of
190 * the object's fields.
191 *
192 * Note that although an object may be in state #4 when kmem initiates the move
193 * request, the object may no longer be in that state by the time kmem actually
194 * calls the move function. Not only does the client free objects
195 * asynchronously, kmem itself puts move requests on a queue where thay are
196 * pending until kmem processes them from another context. Also, objects freed
197 * to a magazine appear allocated from the point of view of the slab layer, so
198 * kmem may even initiate requests for objects in a state other than state #4.
199 *
200 * 2.3.1 Magazine Layer
201 *
202 * An important insight revealed by the states listed above is that the magazine
203 * layer is populated only by kmem_cache_free(). Magazines of constructed
204 * objects are never populated directly from the slab layer (which contains raw,
205 * unconstructed objects). Whenever an allocation request cannot be satisfied
206 * from the magazine layer, the magazines are bypassed and the request is
207 * satisfied from the slab layer (creating a new slab if necessary). kmem calls
208 * the object constructor only when allocating from the slab layer, and only in
209 * response to kmem_cache_alloc() or to prepare the destination buffer passed in
210 * the move callback. kmem does not preconstruct objects in anticipation of
211 * kmem_cache_alloc().
212 *
213 * 2.3.2 Object Constructor and Destructor
214 *
215 * If the client supplies a destructor, it must be valid to call the destructor
216 * on a newly created object (immediately after the constructor).
217 *
218 * 2.4 Recognizing Known Objects
219 *
220 * There is a simple test to determine safely whether or not the client knows
221 * about a given object in the move callback. It relies on the fact that kmem
222 * guarantees that the object of the move callback has only been touched by the
223 * client itself or else by kmem. kmem does this by ensuring that none of the
224 * cache's slabs are freed to the virtual memory (VM) subsystem while a move
225 * callback is pending. When the last object on a slab is freed, if there is a
226 * pending move, kmem puts the slab on a per-cache dead list and defers freeing
227 * slabs on that list until all pending callbacks are completed. That way,
228 * clients can be certain that the object of a move callback is in one of the
229 * states listed above, making it possible to distinguish known objects (in
230 * state #4) using the two low order bits of any pointer member (with the
231 * exception of 'char *' or 'short *' which may not be 4-byte aligned on some
232 * platforms).
233 *
234 * The test works as long as the client always transitions objects from state #4
235 * (known, in use) to state #5 (about to be freed, invalid) by setting the low
236 * order bit of the client-designated pointer member. Since kmem only writes
237 * invalid memory patterns, such as 0xbaddcafe to uninitialized memory and
238 * 0xdeadbeef to freed memory, any scribbling on the object done by kmem is
239 * guaranteed to set at least one of the two low order bits. Therefore, given an
240 * object with a back pointer to a 'container_t *o_container', the client can
241 * test
242 *
243 * container_t *container = object->o_container;
244 * if ((uintptr_t)container & 0x3) {
245 * return (KMEM_CBRC_DONT_KNOW);
246 * }
247 *
248 * Typically, an object will have a pointer to some structure with a list or
249 * hash where objects from the cache are kept while in use. Assuming that the
250 * client has some way of knowing that the container structure is valid and will
251 * not go away during the move, and assuming that the structure includes a lock
252 * to protect whatever collection is used, then the client would continue as
253 * follows:
254 *
255 * // Ensure that the container structure does not go away.
256 * if (container_hold(container) == 0) {
257 * return (KMEM_CBRC_DONT_KNOW);
258 * }
259 * mutex_enter(&container->c_objects_lock);
260 * if (container != object->o_container) {
261 * mutex_exit(&container->c_objects_lock);
262 * container_rele(container);
263 * return (KMEM_CBRC_DONT_KNOW);
264 * }
265 *
266 * At this point the client knows that the object cannot be freed as long as
267 * c_objects_lock is held. Note that after acquiring the lock, the client must
268 * recheck the o_container pointer in case the object was removed just before
269 * acquiring the lock.
270 *
271 * When the client is about to free an object, it must first remove that object
272 * from the list, hash, or other structure where it is kept. At that time, to
273 * mark the object so it can be distinguished from the remaining, known objects,
274 * the client sets the designated low order bit:
275 *
276 * mutex_enter(&container->c_objects_lock);
277 * object->o_container = (void *)((uintptr_t)object->o_container | 0x1);
278 * list_remove(&container->c_objects, object);
279 * mutex_exit(&container->c_objects_lock);
280 *
281 * In the common case, the object is freed to the magazine layer, where it may
282 * be reused on a subsequent allocation without the overhead of calling the
283 * constructor. While in the magazine it appears allocated from the point of
284 * view of the slab layer, making it a candidate for the move callback. Most
285 * objects unrecognized by the client in the move callback fall into this
286 * category and are cheaply distinguished from known objects by the test
287 * described earlier. Since recognition is cheap for the client, and searching
288 * magazines is expensive for kmem, kmem defers searching until the client first
289 * returns KMEM_CBRC_DONT_KNOW. As long as the needed effort is reasonable, kmem
290 * elsewhere does what it can to avoid bothering the client unnecessarily.
291 *
292 * Invalidating the designated pointer member before freeing the object marks
293 * the object to be avoided in the callback, and conversely, assigning a valid
294 * value to the designated pointer member after allocating the object makes the
295 * object fair game for the callback:
296 *
297 * ... allocate object ...
298 * ... set any initial state not set by the constructor ...
299 *
300 * mutex_enter(&container->c_objects_lock);
301 * list_insert_tail(&container->c_objects, object);
302 * membar_producer();
303 * object->o_container = container;
304 * mutex_exit(&container->c_objects_lock);
305 *
306 * Note that everything else must be valid before setting o_container makes the
307 * object fair game for the move callback. The membar_producer() call ensures
308 * that all the object's state is written to memory before setting the pointer
309 * that transitions the object from state #3 or #7 (allocated, constructed, not
310 * yet in use) to state #4 (in use, valid). That's important because the move
311 * function has to check the validity of the pointer before it can safely
312 * acquire the lock protecting the collection where it expects to find known
313 * objects.
314 *
315 * This method of distinguishing known objects observes the usual symmetry:
316 * invalidating the designated pointer is the first thing the client does before
317 * freeing the object, and setting the designated pointer is the last thing the
318 * client does after allocating the object. Of course, the client is not
319 * required to use this method. Fundamentally, how the client recognizes known
320 * objects is completely up to the client, but this method is recommended as an
321 * efficient and safe way to take advantage of the guarantees made by kmem. If
322 * the entire object is arbitrary data without any markable bits from a suitable
323 * pointer member, then the client must find some other method, such as
324 * searching a hash table of known objects.
325 *
326 * 2.5 Preventing Objects From Moving
327 *
328 * Besides a way to distinguish known objects, the other thing that the client
329 * needs is a strategy to ensure that an object will not move while the client
330 * is actively using it. The details of satisfying this requirement tend to be
331 * highly cache-specific. It might seem that the same rules that let a client
332 * remove an object safely should also decide when an object can be moved
333 * safely. However, any object state that makes a removal attempt invalid is
334 * likely to be long-lasting for objects that the client does not expect to
335 * remove. kmem knows nothing about the object state and is equally likely (from
336 * the client's point of view) to request a move for any object in the cache,
337 * whether prepared for removal or not. Even a low percentage of objects stuck
338 * in place by unremovability will defeat the consolidator if the stuck objects
339 * are the same long-lived allocations likely to hold slabs hostage.
340 * Fundamentally, the consolidator is not aimed at common cases. Severe external
341 * fragmentation is a worst case scenario manifested as sparsely allocated
342 * slabs, by definition a low percentage of the cache's objects. When deciding
343 * what makes an object movable, keep in mind the goal of the consolidator: to
344 * bring worst-case external fragmentation within the limits guaranteed for
345 * internal fragmentation. Removability is a poor criterion if it is likely to
346 * exclude more than an insignificant percentage of objects for long periods of
347 * time.
348 *
349 * A tricky general solution exists, and it has the advantage of letting you
350 * move any object at almost any moment, practically eliminating the likelihood
351 * that an object can hold a slab hostage. However, if there is a cache-specific
352 * way to ensure that an object is not actively in use in the vast majority of
353 * cases, a simpler solution that leverages this cache-specific knowledge is
354 * preferred.
355 *
356 * 2.5.1 Cache-Specific Solution
357 *
358 * As an example of a cache-specific solution, the ZFS znode cache takes
359 * advantage of the fact that the vast majority of znodes are only being
360 * referenced from the DNLC. (A typical case might be a few hundred in active
361 * use and a hundred thousand in the DNLC.) In the move callback, after the ZFS
362 * client has established that it recognizes the znode and can access its fields
363 * safely (using the method described earlier), it then tests whether the znode
364 * is referenced by anything other than the DNLC. If so, it assumes that the
365 * znode may be in active use and is unsafe to move, so it drops its locks and
366 * returns KMEM_CBRC_LATER. The advantage of this strategy is that everywhere
367 * else znodes are used, no change is needed to protect against the possibility
368 * of the znode moving. The disadvantage is that it remains possible for an
369 * application to hold a znode slab hostage with an open file descriptor.
370 * However, this case ought to be rare and the consolidator has a way to deal
371 * with it: If the client responds KMEM_CBRC_LATER repeatedly for the same
372 * object, kmem eventually stops believing it and treats the slab as if the
373 * client had responded KMEM_CBRC_NO. Having marked the hostage slab, kmem can
374 * then focus on getting it off of the partial slab list by allocating rather
375 * than freeing all of its objects. (Either way of getting a slab off the
376 * free list reduces fragmentation.)
377 *
378 * 2.5.2 General Solution
379 *
380 * The general solution, on the other hand, requires an explicit hold everywhere
381 * the object is used to prevent it from moving. To keep the client locking
382 * strategy as uncomplicated as possible, kmem guarantees the simplifying
383 * assumption that move callbacks are sequential, even across multiple caches.
384 * Internally, a global queue processed by a single thread supports all caches
385 * implementing the callback function. No matter how many caches supply a move
386 * function, the consolidator never moves more than one object at a time, so the
387 * client does not have to worry about tricky lock ordering involving several
388 * related objects from different kmem caches.
389 *
390 * The general solution implements the explicit hold as a read-write lock, which
391 * allows multiple readers to access an object from the cache simultaneously
392 * while a single writer is excluded from moving it. A single rwlock for the
393 * entire cache would lock out all threads from using any of the cache's objects
394 * even though only a single object is being moved, so to reduce contention,
395 * the client can fan out the single rwlock into an array of rwlocks hashed by
396 * the object address, making it probable that moving one object will not
397 * prevent other threads from using a different object. The rwlock cannot be a
398 * member of the object itself, because the possibility of the object moving
399 * makes it unsafe to access any of the object's fields until the lock is
400 * acquired.
401 *
402 * Assuming a small, fixed number of locks, it's possible that multiple objects
403 * will hash to the same lock. A thread that needs to use multiple objects in
404 * the same function may acquire the same lock multiple times. Since rwlocks are
405 * reentrant for readers, and since there is never more than a single writer at
406 * a time (assuming that the client acquires the lock as a writer only when
407 * moving an object inside the callback), there would seem to be no problem.
408 * However, a client locking multiple objects in the same function must handle
409 * one case of potential deadlock: Assume that thread A needs to prevent both
410 * object 1 and object 2 from moving, and thread B, the callback, meanwhile
411 * tries to move object 3. It's possible, if objects 1, 2, and 3 all hash to the
412 * same lock, that thread A will acquire the lock for object 1 as a reader
413 * before thread B sets the lock's write-wanted bit, preventing thread A from
414 * reacquiring the lock for object 2 as a reader. Unable to make forward
415 * progress, thread A will never release the lock for object 1, resulting in
416 * deadlock.
417 *
418 * There are two ways of avoiding the deadlock just described. The first is to
419 * use rw_tryenter() rather than rw_enter() in the callback function when
420 * attempting to acquire the lock as a writer. If tryenter discovers that the
421 * same object (or another object hashed to the same lock) is already in use, it
422 * aborts the callback and returns KMEM_CBRC_LATER. The second way is to use
423 * rprwlock_t (declared in common/fs/zfs/sys/rprwlock.h) instead of rwlock_t,
424 * since it allows a thread to acquire the lock as a reader in spite of a
425 * waiting writer. This second approach insists on moving the object now, no
426 * matter how many readers the move function must wait for in order to do so,
427 * and could delay the completion of the callback indefinitely (blocking
428 * callbacks to other clients). In practice, a less insistent callback using
429 * rw_tryenter() returns KMEM_CBRC_LATER infrequently enough that there seems
430 * little reason to use anything else.
431 *
432 * Avoiding deadlock is not the only problem that an implementation using an
433 * explicit hold needs to solve. Locking the object in the first place (to
434 * prevent it from moving) remains a problem, since the object could move
435 * between the time you obtain a pointer to the object and the time you acquire
436 * the rwlock hashed to that pointer value. Therefore the client needs to
437 * recheck the value of the pointer after acquiring the lock, drop the lock if
438 * the value has changed, and try again. This requires a level of indirection:
439 * something that points to the object rather than the object itself, that the
440 * client can access safely while attempting to acquire the lock. (The object
441 * itself cannot be referenced safely because it can move at any time.)
442 * The following lock-acquisition function takes whatever is safe to reference
443 * (arg), follows its pointer to the object (using function f), and tries as
444 * often as necessary to acquire the hashed lock and verify that the object
445 * still has not moved:
446 *
447 * object_t *
448 * object_hold(object_f f, void *arg)
449 * {
450 * object_t *op;
451 *
452 * op = f(arg);
453 * if (op == NULL) {
454 * return (NULL);
455 * }
456 *
457 * rw_enter(OBJECT_RWLOCK(op), RW_READER);
458 * while (op != f(arg)) {
459 * rw_exit(OBJECT_RWLOCK(op));
460 * op = f(arg);
461 * if (op == NULL) {
462 * break;
463 * }
464 * rw_enter(OBJECT_RWLOCK(op), RW_READER);
465 * }
466 *
467 * return (op);
468 * }
469 *
470 * The OBJECT_RWLOCK macro hashes the object address to obtain the rwlock. The
471 * lock reacquisition loop, while necessary, almost never executes. The function
472 * pointer f (used to obtain the object pointer from arg) has the following type
473 * definition:
474 *
475 * typedef object_t *(*object_f)(void *arg);
476 *
477 * An object_f implementation is likely to be as simple as accessing a structure
478 * member:
479 *
480 * object_t *
481 * s_object(void *arg)
482 * {
483 * something_t *sp = arg;
484 * return (sp->s_object);
485 * }
486 *
487 * The flexibility of a function pointer allows the path to the object to be
488 * arbitrarily complex and also supports the notion that depending on where you
489 * are using the object, you may need to get it from someplace different.
490 *
491 * The function that releases the explicit hold is simpler because it does not
492 * have to worry about the object moving:
493 *
494 * void
495 * object_rele(object_t *op)
496 * {
497 * rw_exit(OBJECT_RWLOCK(op));
498 * }
499 *
500 * The caller is spared these details so that obtaining and releasing an
501 * explicit hold feels like a simple mutex_enter()/mutex_exit() pair. The caller
502 * of object_hold() only needs to know that the returned object pointer is valid
503 * if not NULL and that the object will not move until released.
504 *
505 * Although object_hold() prevents an object from moving, it does not prevent it
506 * from being freed. The caller must take measures before calling object_hold()
507 * (afterwards is too late) to ensure that the held object cannot be freed. The
508 * caller must do so without accessing the unsafe object reference, so any lock
509 * or reference count used to ensure the continued existence of the object must
510 * live outside the object itself.
511 *
512 * Obtaining a new object is a special case where an explicit hold is impossible
513 * for the caller. Any function that returns a newly allocated object (either as
514 * a return value, or as an in-out paramter) must return it already held; after
515 * the caller gets it is too late, since the object cannot be safely accessed
516 * without the level of indirection described earlier. The following
517 * object_alloc() example uses the same code shown earlier to transition a new
518 * object into the state of being recognized (by the client) as a known object.
519 * The function must acquire the hold (rw_enter) before that state transition
520 * makes the object movable:
521 *
522 * static object_t *
523 * object_alloc(container_t *container)
524 * {
525 * object_t *object = kmem_cache_alloc(object_cache, 0);
526 * ... set any initial state not set by the constructor ...
527 * rw_enter(OBJECT_RWLOCK(object), RW_READER);
528 * mutex_enter(&container->c_objects_lock);
529 * list_insert_tail(&container->c_objects, object);
530 * membar_producer();
531 * object->o_container = container;
532 * mutex_exit(&container->c_objects_lock);
533 * return (object);
534 * }
535 *
536 * Functions that implicitly acquire an object hold (any function that calls
537 * object_alloc() to supply an object for the caller) need to be carefully noted
538 * so that the matching object_rele() is not neglected. Otherwise, leaked holds
539 * prevent all objects hashed to the affected rwlocks from ever being moved.
540 *
541 * The pointer to a held object can be hashed to the holding rwlock even after
542 * the object has been freed. Although it is possible to release the hold
543 * after freeing the object, you may decide to release the hold implicitly in
544 * whatever function frees the object, so as to release the hold as soon as
545 * possible, and for the sake of symmetry with the function that implicitly
546 * acquires the hold when it allocates the object. Here, object_free() releases
547 * the hold acquired by object_alloc(). Its implicit object_rele() forms a
548 * matching pair with object_hold():
549 *
550 * void
551 * object_free(object_t *object)
552 * {
553 * container_t *container;
554 *
555 * ASSERT(object_held(object));
556 * container = object->o_container;
557 * mutex_enter(&container->c_objects_lock);
558 * object->o_container =
559 * (void *)((uintptr_t)object->o_container | 0x1);
560 * list_remove(&container->c_objects, object);
561 * mutex_exit(&container->c_objects_lock);
562 * object_rele(object);
563 * kmem_cache_free(object_cache, object);
564 * }
565 *
566 * Note that object_free() cannot safely accept an object pointer as an argument
567 * unless the object is already held. Any function that calls object_free()
568 * needs to be carefully noted since it similarly forms a matching pair with
569 * object_hold().
570 *
571 * To complete the picture, the following callback function implements the
572 * general solution by moving objects only if they are currently unheld:
573 *
574 * static kmem_cbrc_t
575 * object_move(void *buf, void *newbuf, size_t size, void *arg)
576 * {
577 * object_t *op = buf, *np = newbuf;
578 * container_t *container;
579 *
580 * container = op->o_container;
581 * if ((uintptr_t)container & 0x3) {
582 * return (KMEM_CBRC_DONT_KNOW);
583 * }
584 *
585 * // Ensure that the container structure does not go away.
586 * if (container_hold(container) == 0) {
587 * return (KMEM_CBRC_DONT_KNOW);
588 * }
589 *
590 * mutex_enter(&container->c_objects_lock);
591 * if (container != op->o_container) {
592 * mutex_exit(&container->c_objects_lock);
593 * container_rele(container);
594 * return (KMEM_CBRC_DONT_KNOW);
595 * }
596 *
597 * if (rw_tryenter(OBJECT_RWLOCK(op), RW_WRITER) == 0) {
598 * mutex_exit(&container->c_objects_lock);
599 * container_rele(container);
600 * return (KMEM_CBRC_LATER);
601 * }
602 *
603 * object_move_impl(op, np); // critical section
604 * rw_exit(OBJECT_RWLOCK(op));
605 *
606 * op->o_container = (void *)((uintptr_t)op->o_container | 0x1);
607 * list_link_replace(&op->o_link_node, &np->o_link_node);
608 * mutex_exit(&container->c_objects_lock);
609 * container_rele(container);
610 * return (KMEM_CBRC_YES);
611 * }
612 *
613 * Note that object_move() must invalidate the designated o_container pointer of
614 * the old object in the same way that object_free() does, since kmem will free
615 * the object in response to the KMEM_CBRC_YES return value.
616 *
617 * The lock order in object_move() differs from object_alloc(), which locks
618 * OBJECT_RWLOCK first and &container->c_objects_lock second, but as long as the
619 * callback uses rw_tryenter() (preventing the deadlock described earlier), it's
620 * not a problem. Holding the lock on the object list in the example above
621 * through the entire callback not only prevents the object from going away, it
622 * also allows you to lock the list elsewhere and know that none of its elements
623 * will move during iteration.
624 *
625 * Adding an explicit hold everywhere an object from the cache is used is tricky
626 * and involves much more change to client code than a cache-specific solution
627 * that leverages existing state to decide whether or not an object is
628 * movable. However, this approach has the advantage that no object remains
629 * immovable for any significant length of time, making it extremely unlikely
630 * that long-lived allocations can continue holding slabs hostage; and it works
631 * for any cache.
632 *
633 * 3. Consolidator Implementation
634 *
635 * Once the client supplies a move function that a) recognizes known objects and
636 * b) avoids moving objects that are actively in use, the remaining work is up
637 * to the consolidator to decide which objects to move and when to issue
638 * callbacks.
639 *
640 * The consolidator relies on the fact that a cache's slabs are ordered by
641 * usage. Each slab has a fixed number of objects. Depending on the slab's
642 * "color" (the offset of the first object from the beginning of the slab;
643 * offsets are staggered to mitigate false sharing of cache lines) it is either
644 * the maximum number of objects per slab determined at cache creation time or
645 * else the number closest to the maximum that fits within the space remaining
646 * after the initial offset. A completely allocated slab may contribute some
647 * internal fragmentation (per-slab overhead) but no external fragmentation, so
648 * it is of no interest to the consolidator. At the other extreme, slabs whose
649 * objects have all been freed to the slab are released to the virtual memory
650 * (VM) subsystem (objects freed to magazines are still allocated as far as the
651 * slab is concerned). External fragmentation exists when there are slabs
652 * somewhere between these extremes. A partial slab has at least one but not all
653 * of its objects allocated. The more partial slabs, and the fewer allocated
654 * objects on each of them, the higher the fragmentation. Hence the
655 * consolidator's overall strategy is to reduce the number of partial slabs by
656 * moving allocated objects from the least allocated slabs to the most allocated
657 * slabs.
658 *
659 * Partial slabs are kept in an AVL tree ordered by usage. Completely allocated
660 * slabs are kept separately in an unordered list. Since the majority of slabs
661 * tend to be completely allocated (a typical unfragmented cache may have
662 * thousands of complete slabs and only a single partial slab), separating
663 * complete slabs improves the efficiency of partial slab ordering, since the
664 * complete slabs do not affect the depth or balance of the AVL tree. This
665 * ordered sequence of partial slabs acts as a "free list" supplying objects for
666 * allocation requests.
667 *
668 * Objects are always allocated from the first partial slab in the free list,
669 * where the allocation is most likely to eliminate a partial slab (by
670 * completely allocating it). Conversely, when a single object from a completely
671 * allocated slab is freed to the slab, that slab is added to the front of the
672 * free list. Since most free list activity involves highly allocated slabs
673 * coming and going at the front of the list, slabs tend naturally toward the
674 * ideal order: highly allocated at the front, sparsely allocated at the back.
675 * Slabs with few allocated objects are likely to become completely free if they
676 * keep a safe distance away from the front of the free list. Slab misorders
677 * interfere with the natural tendency of slabs to become completely free or
678 * completely allocated. For example, a slab with a single allocated object
679 * needs only a single free to escape the cache; its natural desire is
680 * frustrated when it finds itself at the front of the list where a second
681 * allocation happens just before the free could have released it. Another slab
682 * with all but one object allocated might have supplied the buffer instead, so
683 * that both (as opposed to neither) of the slabs would have been taken off the
684 * free list.
685 *
686 * Although slabs tend naturally toward the ideal order, misorders allowed by a
687 * simple list implementation defeat the consolidator's strategy of merging
688 * least- and most-allocated slabs. Without an AVL tree to guarantee order, kmem
689 * needs another way to fix misorders to optimize its callback strategy. One
690 * approach is to periodically scan a limited number of slabs, advancing a
691 * marker to hold the current scan position, and to move extreme misorders to
692 * the front or back of the free list and to the front or back of the current
693 * scan range. By making consecutive scan ranges overlap by one slab, the least
694 * allocated slab in the current range can be carried along from the end of one
695 * scan to the start of the next.
696 *
697 * Maintaining partial slabs in an AVL tree relieves kmem of this additional
698 * task, however. Since most of the cache's activity is in the magazine layer,
699 * and allocations from the slab layer represent only a startup cost, the
700 * overhead of maintaining a balanced tree is not a significant concern compared
701 * to the opportunity of reducing complexity by eliminating the partial slab
702 * scanner just described. The overhead of an AVL tree is minimized by
703 * maintaining only partial slabs in the tree and keeping completely allocated
704 * slabs separately in a list. To avoid increasing the size of the slab
705 * structure the AVL linkage pointers are reused for the slab's list linkage,
706 * since the slab will always be either partial or complete, never stored both
707 * ways at the same time. To further minimize the overhead of the AVL tree the
708 * compare function that orders partial slabs by usage divides the range of
709 * allocated object counts into bins such that counts within the same bin are
710 * considered equal. Binning partial slabs makes it less likely that allocating
711 * or freeing a single object will change the slab's order, requiring a tree
712 * reinsertion (an avl_remove() followed by an avl_add(), both potentially
713 * requiring some rebalancing of the tree). Allocation counts closest to
714 * completely free and completely allocated are left unbinned (finely sorted) to
715 * better support the consolidator's strategy of merging slabs at either
716 * extreme.
717 *
718 * 3.1 Assessing Fragmentation and Selecting Candidate Slabs
719 *
720 * The consolidator piggybacks on the kmem maintenance thread and is called on
721 * the same interval as kmem_cache_update(), once per cache every fifteen
722 * seconds. kmem maintains a running count of unallocated objects in the slab
723 * layer (cache_bufslab). The consolidator checks whether that number exceeds
724 * 12.5% (1/8) of the total objects in the cache (cache_buftotal), and whether
725 * there is a significant number of slabs in the cache (arbitrarily a minimum
726 * 101 total slabs). Unused objects that have fallen out of the magazine layer's
727 * working set are included in the assessment, and magazines in the depot are
728 * reaped if those objects would lift cache_bufslab above the fragmentation
729 * threshold. Once the consolidator decides that a cache is fragmented, it looks
730 * for a candidate slab to reclaim, starting at the end of the partial slab free
731 * list and scanning backwards. At first the consolidator is choosy: only a slab
732 * with fewer than 12.5% (1/8) of its objects allocated qualifies (or else a
733 * single allocated object, regardless of percentage). If there is difficulty
734 * finding a candidate slab, kmem raises the allocation threshold incrementally,
735 * up to a maximum 87.5% (7/8), so that eventually the consolidator will reduce
736 * external fragmentation (unused objects on the free list) below 12.5% (1/8),
737 * even in the worst case of every slab in the cache being almost 7/8 allocated.
738 * The threshold can also be lowered incrementally when candidate slabs are easy
739 * to find, and the threshold is reset to the minimum 1/8 as soon as the cache
740 * is no longer fragmented.
741 *
742 * 3.2 Generating Callbacks
743 *
744 * Once an eligible slab is chosen, a callback is generated for every allocated
745 * object on the slab, in the hope that the client will move everything off the
746 * slab and make it reclaimable. Objects selected as move destinations are
747 * chosen from slabs at the front of the free list. Assuming slabs in the ideal
748 * order (most allocated at the front, least allocated at the back) and a
749 * cooperative client, the consolidator will succeed in removing slabs from both
750 * ends of the free list, completely allocating on the one hand and completely
751 * freeing on the other. Objects selected as move destinations are allocated in
752 * the kmem maintenance thread where move requests are enqueued. A separate
753 * callback thread removes pending callbacks from the queue and calls the
754 * client. The separate thread ensures that client code (the move function) does
755 * not interfere with internal kmem maintenance tasks. A map of pending
756 * callbacks keyed by object address (the object to be moved) is checked to
757 * ensure that duplicate callbacks are not generated for the same object.
758 * Allocating the move destination (the object to move to) prevents subsequent
759 * callbacks from selecting the same destination as an earlier pending callback.
760 *
761 * Move requests can also be generated by kmem_cache_reap() when the system is
762 * desperate for memory and by kmem_cache_move_notify(), called by the client to
763 * notify kmem that a move refused earlier with KMEM_CBRC_LATER is now possible.
764 * The map of pending callbacks is protected by the same lock that protects the
765 * slab layer.
766 *
767 * When the system is desperate for memory, kmem does not bother to determine
768 * whether or not the cache exceeds the fragmentation threshold, but tries to
769 * consolidate as many slabs as possible. Normally, the consolidator chews
770 * slowly, one sparsely allocated slab at a time during each maintenance
771 * interval that the cache is fragmented. When desperate, the consolidator
772 * starts at the last partial slab and enqueues callbacks for every allocated
773 * object on every partial slab, working backwards until it reaches the first
774 * partial slab. The first partial slab, meanwhile, advances in pace with the
775 * consolidator as allocations to supply move destinations for the enqueued
776 * callbacks use up the highly allocated slabs at the front of the free list.
777 * Ideally, the overgrown free list collapses like an accordion, starting at
778 * both ends and ending at the center with a single partial slab.
779 *
780 * 3.3 Client Responses
781 *
782 * When the client returns KMEM_CBRC_NO in response to the move callback, kmem
783 * marks the slab that supplied the stuck object non-reclaimable and moves it to
784 * front of the free list. The slab remains marked as long as it remains on the
785 * free list, and it appears more allocated to the partial slab compare function
786 * than any unmarked slab, no matter how many of its objects are allocated.
787 * Since even one immovable object ties up the entire slab, the goal is to
788 * completely allocate any slab that cannot be completely freed. kmem does not
789 * bother generating callbacks to move objects from a marked slab unless the
790 * system is desperate.
791 *
792 * When the client responds KMEM_CBRC_LATER, kmem increments a count for the
793 * slab. If the client responds LATER too many times, kmem disbelieves and
794 * treats the response as a NO. The count is cleared when the slab is taken off
795 * the partial slab list or when the client moves one of the slab's objects.
796 *
797 * 4. Observability
798 *
799 * A kmem cache's external fragmentation is best observed with 'mdb -k' using
800 * the ::kmem_slabs dcmd. For a complete description of the command, enter
801 * '::help kmem_slabs' at the mdb prompt.
802 */
803
804 #include <sys/kmem_impl.h>
805 #include <sys/vmem_impl.h>
806 #include <sys/param.h>
807 #include <sys/sysmacros.h>
808 #include <sys/vm.h>
809 #include <sys/proc.h>
810 #include <sys/tuneable.h>
811 #include <sys/systm.h>
812 #include <sys/cmn_err.h>
813 #include <sys/debug.h>
814 #include <sys/sdt.h>
815 #include <sys/mutex.h>
816 #include <sys/bitmap.h>
817 #include <sys/atomic.h>
818 #include <sys/kobj.h>
819 #include <sys/disp.h>
820 #include <vm/seg_kmem.h>
821 #include <sys/log.h>
822 #include <sys/callb.h>
823 #include <sys/taskq.h>
824 #include <sys/modctl.h>
825 #include <sys/reboot.h>
826 #include <sys/id32.h>
827 #include <sys/zone.h>
828 #include <sys/netstack.h>
829 #ifdef DEBUG
830 #include <sys/random.h>
831 #endif
832
833 extern void streams_msg_init(void);
834 extern int segkp_fromheap;
835 extern void segkp_cache_free(void);
836 extern int callout_init_done;
837
838 struct kmem_cache_kstat {
839 kstat_named_t kmc_buf_size;
840 kstat_named_t kmc_align;
841 kstat_named_t kmc_chunk_size;
842 kstat_named_t kmc_slab_size;
843 kstat_named_t kmc_alloc;
844 kstat_named_t kmc_alloc_fail;
845 kstat_named_t kmc_free;
846 kstat_named_t kmc_depot_alloc;
847 kstat_named_t kmc_depot_free;
848 kstat_named_t kmc_depot_contention;
849 kstat_named_t kmc_slab_alloc;
850 kstat_named_t kmc_slab_free;
851 kstat_named_t kmc_buf_constructed;
852 kstat_named_t kmc_buf_avail;
853 kstat_named_t kmc_buf_inuse;
854 kstat_named_t kmc_buf_total;
855 kstat_named_t kmc_buf_max;
856 kstat_named_t kmc_slab_create;
857 kstat_named_t kmc_slab_destroy;
858 kstat_named_t kmc_vmem_source;
859 kstat_named_t kmc_hash_size;
860 kstat_named_t kmc_hash_lookup_depth;
861 kstat_named_t kmc_hash_rescale;
862 kstat_named_t kmc_full_magazines;
863 kstat_named_t kmc_empty_magazines;
864 kstat_named_t kmc_magazine_size;
865 kstat_named_t kmc_reap; /* number of kmem_cache_reap() calls */
866 kstat_named_t kmc_defrag; /* attempts to defrag all partial slabs */
867 kstat_named_t kmc_scan; /* attempts to defrag one partial slab */
868 kstat_named_t kmc_move_callbacks; /* sum of yes, no, later, dn, dk */
869 kstat_named_t kmc_move_yes;
870 kstat_named_t kmc_move_no;
871 kstat_named_t kmc_move_later;
872 kstat_named_t kmc_move_dont_need;
873 kstat_named_t kmc_move_dont_know; /* obj unrecognized by client ... */
874 kstat_named_t kmc_move_hunt_found; /* ... but found in mag layer */
875 kstat_named_t kmc_move_slabs_freed; /* slabs freed by consolidator */
876 kstat_named_t kmc_move_reclaimable; /* buffers, if consolidator ran */
877 } kmem_cache_kstat = {
878 { "buf_size", KSTAT_DATA_UINT64 },
879 { "align", KSTAT_DATA_UINT64 },
880 { "chunk_size", KSTAT_DATA_UINT64 },
881 { "slab_size", KSTAT_DATA_UINT64 },
882 { "alloc", KSTAT_DATA_UINT64 },
883 { "alloc_fail", KSTAT_DATA_UINT64 },
884 { "free", KSTAT_DATA_UINT64 },
885 { "depot_alloc", KSTAT_DATA_UINT64 },
886 { "depot_free", KSTAT_DATA_UINT64 },
887 { "depot_contention", KSTAT_DATA_UINT64 },
888 { "slab_alloc", KSTAT_DATA_UINT64 },
889 { "slab_free", KSTAT_DATA_UINT64 },
890 { "buf_constructed", KSTAT_DATA_UINT64 },
891 { "buf_avail", KSTAT_DATA_UINT64 },
892 { "buf_inuse", KSTAT_DATA_UINT64 },
893 { "buf_total", KSTAT_DATA_UINT64 },
894 { "buf_max", KSTAT_DATA_UINT64 },
895 { "slab_create", KSTAT_DATA_UINT64 },
896 { "slab_destroy", KSTAT_DATA_UINT64 },
897 { "vmem_source", KSTAT_DATA_UINT64 },
898 { "hash_size", KSTAT_DATA_UINT64 },
899 { "hash_lookup_depth", KSTAT_DATA_UINT64 },
900 { "hash_rescale", KSTAT_DATA_UINT64 },
901 { "full_magazines", KSTAT_DATA_UINT64 },
902 { "empty_magazines", KSTAT_DATA_UINT64 },
903 { "magazine_size", KSTAT_DATA_UINT64 },
904 { "reap", KSTAT_DATA_UINT64 },
905 { "defrag", KSTAT_DATA_UINT64 },
906 { "scan", KSTAT_DATA_UINT64 },
907 { "move_callbacks", KSTAT_DATA_UINT64 },
908 { "move_yes", KSTAT_DATA_UINT64 },
909 { "move_no", KSTAT_DATA_UINT64 },
910 { "move_later", KSTAT_DATA_UINT64 },
911 { "move_dont_need", KSTAT_DATA_UINT64 },
912 { "move_dont_know", KSTAT_DATA_UINT64 },
913 { "move_hunt_found", KSTAT_DATA_UINT64 },
914 { "move_slabs_freed", KSTAT_DATA_UINT64 },
915 { "move_reclaimable", KSTAT_DATA_UINT64 },
916 };
917
918 static kmutex_t kmem_cache_kstat_lock;
919
920 /*
921 * The default set of caches to back kmem_alloc().
922 * These sizes should be reevaluated periodically.
923 *
924 * We want allocations that are multiples of the coherency granularity
925 * (64 bytes) to be satisfied from a cache which is a multiple of 64
926 * bytes, so that it will be 64-byte aligned. For all multiples of 64,
927 * the next kmem_cache_size greater than or equal to it must be a
928 * multiple of 64.
929 *
930 * We split the table into two sections: size <= 4k and size > 4k. This
931 * saves a lot of space and cache footprint in our cache tables.
932 */
933 static const int kmem_alloc_sizes[] = {
934 1 * 8,
935 2 * 8,
936 3 * 8,
937 4 * 8, 5 * 8, 6 * 8, 7 * 8,
938 4 * 16, 5 * 16, 6 * 16, 7 * 16,
939 4 * 32, 5 * 32, 6 * 32, 7 * 32,
940 4 * 64, 5 * 64, 6 * 64, 7 * 64,
941 4 * 128, 5 * 128, 6 * 128, 7 * 128,
942 P2ALIGN(8192 / 7, 64),
943 P2ALIGN(8192 / 6, 64),
944 P2ALIGN(8192 / 5, 64),
945 P2ALIGN(8192 / 4, 64),
946 P2ALIGN(8192 / 3, 64),
947 P2ALIGN(8192 / 2, 64),
948 };
949
950 static const int kmem_big_alloc_sizes[] = {
951 2 * 4096, 3 * 4096,
952 2 * 8192, 3 * 8192,
953 4 * 8192, 5 * 8192, 6 * 8192, 7 * 8192,
954 8 * 8192, 9 * 8192, 10 * 8192, 11 * 8192,
955 12 * 8192, 13 * 8192, 14 * 8192, 15 * 8192,
956 16 * 8192
957 };
958
959 #define KMEM_MAXBUF 4096
960 #define KMEM_BIG_MAXBUF_32BIT 32768
961 #define KMEM_BIG_MAXBUF 131072
962
963 #define KMEM_BIG_MULTIPLE 4096 /* big_alloc_sizes must be a multiple */
964 #define KMEM_BIG_SHIFT 12 /* lg(KMEM_BIG_MULTIPLE) */
965
966 static kmem_cache_t *kmem_alloc_table[KMEM_MAXBUF >> KMEM_ALIGN_SHIFT];
967 static kmem_cache_t *kmem_big_alloc_table[KMEM_BIG_MAXBUF >> KMEM_BIG_SHIFT];
968
969 #define KMEM_ALLOC_TABLE_MAX (KMEM_MAXBUF >> KMEM_ALIGN_SHIFT)
970 static size_t kmem_big_alloc_table_max = 0; /* # of filled elements */
971
972 static kmem_magtype_t kmem_magtype[] = {
973 { 1, 8, 3200, 65536 },
974 { 3, 16, 256, 32768 },
975 { 7, 32, 64, 16384 },
976 { 15, 64, 0, 8192 },
977 { 31, 64, 0, 4096 },
978 { 47, 64, 0, 2048 },
979 { 63, 64, 0, 1024 },
980 { 95, 64, 0, 512 },
981 { 143, 64, 0, 0 },
982 };
983
984 static uint32_t kmem_reaping;
985 static uint32_t kmem_reaping_idspace;
986
987 /*
988 * kmem tunables
989 */
990 clock_t kmem_reap_interval; /* cache reaping rate [15 * HZ ticks] */
991 int kmem_depot_contention = 3; /* max failed tryenters per real interval */
992 pgcnt_t kmem_reapahead = 0; /* start reaping N pages before pageout */
993 int kmem_panic = 1; /* whether to panic on error */
994 int kmem_logging = 1; /* kmem_log_enter() override */
995 uint32_t kmem_mtbf = 0; /* mean time between failures [default: off] */
996 size_t kmem_transaction_log_size; /* transaction log size [2% of memory] */
997 size_t kmem_content_log_size; /* content log size [2% of memory] */
998 size_t kmem_failure_log_size; /* failure log [4 pages per CPU] */
999 size_t kmem_slab_log_size; /* slab create log [4 pages per CPU] */
1000 size_t kmem_content_maxsave = 256; /* KMF_CONTENTS max bytes to log */
1001 size_t kmem_lite_minsize = 0; /* minimum buffer size for KMF_LITE */
1002 size_t kmem_lite_maxalign = 1024; /* maximum buffer alignment for KMF_LITE */
1003 int kmem_lite_pcs = 4; /* number of PCs to store in KMF_LITE mode */
1004 size_t kmem_maxverify; /* maximum bytes to inspect in debug routines */
1005 size_t kmem_minfirewall; /* hardware-enforced redzone threshold */
1006
1007 #ifdef _LP64
1008 size_t kmem_max_cached = KMEM_BIG_MAXBUF; /* maximum kmem_alloc cache */
1009 #else
1010 size_t kmem_max_cached = KMEM_BIG_MAXBUF_32BIT; /* maximum kmem_alloc cache */
1011 #endif
1012
1013 #ifdef DEBUG
1014 int kmem_flags = KMF_AUDIT | KMF_DEADBEEF | KMF_REDZONE | KMF_CONTENTS;
1015 #else
1016 int kmem_flags = 0;
1017 #endif
1018 int kmem_ready;
1019
1020 static kmem_cache_t *kmem_slab_cache;
1021 static kmem_cache_t *kmem_bufctl_cache;
1022 static kmem_cache_t *kmem_bufctl_audit_cache;
1023
1024 static kmutex_t kmem_cache_lock; /* inter-cache linkage only */
1025 static list_t kmem_caches;
1026
1027 static taskq_t *kmem_taskq;
1028 static kmutex_t kmem_flags_lock;
1029 static vmem_t *kmem_metadata_arena;
1030 static vmem_t *kmem_msb_arena; /* arena for metadata caches */
1031 static vmem_t *kmem_cache_arena;
1032 static vmem_t *kmem_hash_arena;
1033 static vmem_t *kmem_log_arena;
1034 static vmem_t *kmem_oversize_arena;
1035 static vmem_t *kmem_va_arena;
1036 static vmem_t *kmem_default_arena;
1037 static vmem_t *kmem_firewall_va_arena;
1038 static vmem_t *kmem_firewall_arena;
1039
1040 /*
1041 * Define KMEM_STATS to turn on statistic gathering. By default, it is only
1042 * turned on when DEBUG is also defined.
1043 */
1044 #ifdef DEBUG
1045 #define KMEM_STATS
1046 #endif /* DEBUG */
1047
1048 #ifdef KMEM_STATS
1049 #define KMEM_STAT_ADD(stat) ((stat)++)
1050 #define KMEM_STAT_COND_ADD(cond, stat) ((void) (!(cond) || (stat)++))
1051 #else
1052 #define KMEM_STAT_ADD(stat) /* nothing */
1053 #define KMEM_STAT_COND_ADD(cond, stat) /* nothing */
1054 #endif /* KMEM_STATS */
1055
1056 /*
1057 * kmem slab consolidator thresholds (tunables)
1058 */
1059 size_t kmem_frag_minslabs = 101; /* minimum total slabs */
1060 size_t kmem_frag_numer = 1; /* free buffers (numerator) */
1061 size_t kmem_frag_denom = KMEM_VOID_FRACTION; /* buffers (denominator) */
1062 /*
1063 * Maximum number of slabs from which to move buffers during a single
1064 * maintenance interval while the system is not low on memory.
1065 */
1066 size_t kmem_reclaim_max_slabs = 1;
1067 /*
1068 * Number of slabs to scan backwards from the end of the partial slab list
1069 * when searching for buffers to relocate.
1070 */
1071 size_t kmem_reclaim_scan_range = 12;
1072
1073 #ifdef KMEM_STATS
1074 static struct {
1075 uint64_t kms_callbacks;
1076 uint64_t kms_yes;
1077 uint64_t kms_no;
1078 uint64_t kms_later;
1079 uint64_t kms_dont_need;
1080 uint64_t kms_dont_know;
1081 uint64_t kms_hunt_found_mag;
1082 uint64_t kms_hunt_found_slab;
1083 uint64_t kms_hunt_alloc_fail;
1084 uint64_t kms_hunt_lucky;
1085 uint64_t kms_notify;
1086 uint64_t kms_notify_callbacks;
1087 uint64_t kms_disbelief;
1088 uint64_t kms_already_pending;
1089 uint64_t kms_callback_alloc_fail;
1090 uint64_t kms_callback_taskq_fail;
1091 uint64_t kms_endscan_slab_dead;
1092 uint64_t kms_endscan_slab_destroyed;
1093 uint64_t kms_endscan_nomem;
1094 uint64_t kms_endscan_refcnt_changed;
1095 uint64_t kms_endscan_nomove_changed;
1096 uint64_t kms_endscan_freelist;
1097 uint64_t kms_avl_update;
1098 uint64_t kms_avl_noupdate;
1099 uint64_t kms_no_longer_reclaimable;
1100 uint64_t kms_notify_no_longer_reclaimable;
1101 uint64_t kms_notify_slab_dead;
1102 uint64_t kms_notify_slab_destroyed;
1103 uint64_t kms_alloc_fail;
1104 uint64_t kms_constructor_fail;
1105 uint64_t kms_dead_slabs_freed;
1106 uint64_t kms_defrags;
1107 uint64_t kms_scans;
1108 uint64_t kms_scan_depot_ws_reaps;
1109 uint64_t kms_debug_reaps;
1110 uint64_t kms_debug_scans;
1111 } kmem_move_stats;
1112 #endif /* KMEM_STATS */
1113
1114 /* consolidator knobs */
1115 static boolean_t kmem_move_noreap;
1116 static boolean_t kmem_move_blocked;
1117 static boolean_t kmem_move_fulltilt;
1118 static boolean_t kmem_move_any_partial;
1119
1120 #ifdef DEBUG
1121 /*
1122 * kmem consolidator debug tunables:
1123 * Ensure code coverage by occasionally running the consolidator even when the
1124 * caches are not fragmented (they may never be). These intervals are mean time
1125 * in cache maintenance intervals (kmem_cache_update).
1126 */
1127 uint32_t kmem_mtb_move = 60; /* defrag 1 slab (~15min) */
1128 uint32_t kmem_mtb_reap = 1800; /* defrag all slabs (~7.5hrs) */
1129 #endif /* DEBUG */
1130
1131 static kmem_cache_t *kmem_defrag_cache;
1132 static kmem_cache_t *kmem_move_cache;
1133 static taskq_t *kmem_move_taskq;
1134
1135 static void kmem_cache_scan(kmem_cache_t *);
1136 static void kmem_cache_defrag(kmem_cache_t *);
1137 static void kmem_slab_prefill(kmem_cache_t *, kmem_slab_t *);
1138
1139
1140 kmem_log_header_t *kmem_transaction_log;
1141 kmem_log_header_t *kmem_content_log;
1142 kmem_log_header_t *kmem_failure_log;
1143 kmem_log_header_t *kmem_slab_log;
1144
1145 static int kmem_lite_count; /* # of PCs in kmem_buftag_lite_t */
1146
1147 #define KMEM_BUFTAG_LITE_ENTER(bt, count, caller) \
1148 if ((count) > 0) { \
1149 pc_t *_s = ((kmem_buftag_lite_t *)(bt))->bt_history; \
1150 pc_t *_e; \
1151 /* memmove() the old entries down one notch */ \
1152 for (_e = &_s[(count) - 1]; _e > _s; _e--) \
1153 *_e = *(_e - 1); \
1154 *_s = (uintptr_t)(caller); \
1155 }
1156
1157 #define KMERR_MODIFIED 0 /* buffer modified while on freelist */
1158 #define KMERR_REDZONE 1 /* redzone violation (write past end of buf) */
1159 #define KMERR_DUPFREE 2 /* freed a buffer twice */
1160 #define KMERR_BADADDR 3 /* freed a bad (unallocated) address */
1161 #define KMERR_BADBUFTAG 4 /* buftag corrupted */
1162 #define KMERR_BADBUFCTL 5 /* bufctl corrupted */
1163 #define KMERR_BADCACHE 6 /* freed a buffer to the wrong cache */
1164 #define KMERR_BADSIZE 7 /* alloc size != free size */
1165 #define KMERR_BADBASE 8 /* buffer base address wrong */
1166
1167 struct {
1168 hrtime_t kmp_timestamp; /* timestamp of panic */
1169 int kmp_error; /* type of kmem error */
1170 void *kmp_buffer; /* buffer that induced panic */
1171 void *kmp_realbuf; /* real start address for buffer */
1172 kmem_cache_t *kmp_cache; /* buffer's cache according to client */
1173 kmem_cache_t *kmp_realcache; /* actual cache containing buffer */
1174 kmem_slab_t *kmp_slab; /* slab accoring to kmem_findslab() */
1175 kmem_bufctl_t *kmp_bufctl; /* bufctl */
1176 } kmem_panic_info;
1177
1178
1179 static void
copy_pattern(uint64_t pattern,void * buf_arg,size_t size)1180 copy_pattern(uint64_t pattern, void *buf_arg, size_t size)
1181 {
1182 uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1183 uint64_t *buf = buf_arg;
1184
1185 while (buf < bufend)
1186 *buf++ = pattern;
1187 }
1188
1189 static void *
verify_pattern(uint64_t pattern,void * buf_arg,size_t size)1190 verify_pattern(uint64_t pattern, void *buf_arg, size_t size)
1191 {
1192 uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1193 uint64_t *buf;
1194
1195 for (buf = buf_arg; buf < bufend; buf++)
1196 if (*buf != pattern)
1197 return (buf);
1198 return (NULL);
1199 }
1200
1201 static void *
verify_and_copy_pattern(uint64_t old,uint64_t new,void * buf_arg,size_t size)1202 verify_and_copy_pattern(uint64_t old, uint64_t new, void *buf_arg, size_t size)
1203 {
1204 uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1205 uint64_t *buf;
1206
1207 for (buf = buf_arg; buf < bufend; buf++) {
1208 if (*buf != old) {
1209 copy_pattern(old, buf_arg,
1210 (char *)buf - (char *)buf_arg);
1211 return (buf);
1212 }
1213 *buf = new;
1214 }
1215
1216 return (NULL);
1217 }
1218
1219 static void
kmem_cache_applyall(void (* func)(kmem_cache_t *),taskq_t * tq,int tqflag)1220 kmem_cache_applyall(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1221 {
1222 kmem_cache_t *cp;
1223
1224 mutex_enter(&kmem_cache_lock);
1225 for (cp = list_head(&kmem_caches); cp != NULL;
1226 cp = list_next(&kmem_caches, cp))
1227 if (tq != NULL)
1228 (void) taskq_dispatch(tq, (task_func_t *)func, cp,
1229 tqflag);
1230 else
1231 func(cp);
1232 mutex_exit(&kmem_cache_lock);
1233 }
1234
1235 static void
kmem_cache_applyall_id(void (* func)(kmem_cache_t *),taskq_t * tq,int tqflag)1236 kmem_cache_applyall_id(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1237 {
1238 kmem_cache_t *cp;
1239
1240 mutex_enter(&kmem_cache_lock);
1241 for (cp = list_head(&kmem_caches); cp != NULL;
1242 cp = list_next(&kmem_caches, cp)) {
1243 if (!(cp->cache_cflags & KMC_IDENTIFIER))
1244 continue;
1245 if (tq != NULL)
1246 (void) taskq_dispatch(tq, (task_func_t *)func, cp,
1247 tqflag);
1248 else
1249 func(cp);
1250 }
1251 mutex_exit(&kmem_cache_lock);
1252 }
1253
1254 /*
1255 * Debugging support. Given a buffer address, find its slab.
1256 */
1257 static kmem_slab_t *
kmem_findslab(kmem_cache_t * cp,void * buf)1258 kmem_findslab(kmem_cache_t *cp, void *buf)
1259 {
1260 kmem_slab_t *sp;
1261
1262 mutex_enter(&cp->cache_lock);
1263 for (sp = list_head(&cp->cache_complete_slabs); sp != NULL;
1264 sp = list_next(&cp->cache_complete_slabs, sp)) {
1265 if (KMEM_SLAB_MEMBER(sp, buf)) {
1266 mutex_exit(&cp->cache_lock);
1267 return (sp);
1268 }
1269 }
1270 for (sp = avl_first(&cp->cache_partial_slabs); sp != NULL;
1271 sp = AVL_NEXT(&cp->cache_partial_slabs, sp)) {
1272 if (KMEM_SLAB_MEMBER(sp, buf)) {
1273 mutex_exit(&cp->cache_lock);
1274 return (sp);
1275 }
1276 }
1277 mutex_exit(&cp->cache_lock);
1278
1279 return (NULL);
1280 }
1281
1282 static void
kmem_error(int error,kmem_cache_t * cparg,void * bufarg)1283 kmem_error(int error, kmem_cache_t *cparg, void *bufarg)
1284 {
1285 kmem_buftag_t *btp = NULL;
1286 kmem_bufctl_t *bcp = NULL;
1287 kmem_cache_t *cp = cparg;
1288 kmem_slab_t *sp;
1289 uint64_t *off;
1290 void *buf = bufarg;
1291
1292 kmem_logging = 0; /* stop logging when a bad thing happens */
1293
1294 kmem_panic_info.kmp_timestamp = gethrtime();
1295
1296 sp = kmem_findslab(cp, buf);
1297 if (sp == NULL) {
1298 for (cp = list_tail(&kmem_caches); cp != NULL;
1299 cp = list_prev(&kmem_caches, cp)) {
1300 if ((sp = kmem_findslab(cp, buf)) != NULL)
1301 break;
1302 }
1303 }
1304
1305 if (sp == NULL) {
1306 cp = NULL;
1307 error = KMERR_BADADDR;
1308 } else {
1309 if (cp != cparg)
1310 error = KMERR_BADCACHE;
1311 else
1312 buf = (char *)bufarg - ((uintptr_t)bufarg -
1313 (uintptr_t)sp->slab_base) % cp->cache_chunksize;
1314 if (buf != bufarg)
1315 error = KMERR_BADBASE;
1316 if (cp->cache_flags & KMF_BUFTAG)
1317 btp = KMEM_BUFTAG(cp, buf);
1318 if (cp->cache_flags & KMF_HASH) {
1319 mutex_enter(&cp->cache_lock);
1320 for (bcp = *KMEM_HASH(cp, buf); bcp; bcp = bcp->bc_next)
1321 if (bcp->bc_addr == buf)
1322 break;
1323 mutex_exit(&cp->cache_lock);
1324 if (bcp == NULL && btp != NULL)
1325 bcp = btp->bt_bufctl;
1326 if (kmem_findslab(cp->cache_bufctl_cache, bcp) ==
1327 NULL || P2PHASE((uintptr_t)bcp, KMEM_ALIGN) ||
1328 bcp->bc_addr != buf) {
1329 error = KMERR_BADBUFCTL;
1330 bcp = NULL;
1331 }
1332 }
1333 }
1334
1335 kmem_panic_info.kmp_error = error;
1336 kmem_panic_info.kmp_buffer = bufarg;
1337 kmem_panic_info.kmp_realbuf = buf;
1338 kmem_panic_info.kmp_cache = cparg;
1339 kmem_panic_info.kmp_realcache = cp;
1340 kmem_panic_info.kmp_slab = sp;
1341 kmem_panic_info.kmp_bufctl = bcp;
1342
1343 printf("kernel memory allocator: ");
1344
1345 switch (error) {
1346
1347 case KMERR_MODIFIED:
1348 printf("buffer modified after being freed\n");
1349 off = verify_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1350 if (off == NULL) /* shouldn't happen */
1351 off = buf;
1352 printf("modification occurred at offset 0x%lx "
1353 "(0x%llx replaced by 0x%llx)\n",
1354 (uintptr_t)off - (uintptr_t)buf,
1355 (longlong_t)KMEM_FREE_PATTERN, (longlong_t)*off);
1356 break;
1357
1358 case KMERR_REDZONE:
1359 printf("redzone violation: write past end of buffer\n");
1360 break;
1361
1362 case KMERR_BADADDR:
1363 printf("invalid free: buffer not in cache\n");
1364 break;
1365
1366 case KMERR_DUPFREE:
1367 printf("duplicate free: buffer freed twice\n");
1368 break;
1369
1370 case KMERR_BADBUFTAG:
1371 printf("boundary tag corrupted\n");
1372 printf("bcp ^ bxstat = %lx, should be %lx\n",
1373 (intptr_t)btp->bt_bufctl ^ btp->bt_bxstat,
1374 KMEM_BUFTAG_FREE);
1375 break;
1376
1377 case KMERR_BADBUFCTL:
1378 printf("bufctl corrupted\n");
1379 break;
1380
1381 case KMERR_BADCACHE:
1382 printf("buffer freed to wrong cache\n");
1383 printf("buffer was allocated from %s,\n", cp->cache_name);
1384 printf("caller attempting free to %s.\n", cparg->cache_name);
1385 break;
1386
1387 case KMERR_BADSIZE:
1388 printf("bad free: free size (%u) != alloc size (%u)\n",
1389 KMEM_SIZE_DECODE(((uint32_t *)btp)[0]),
1390 KMEM_SIZE_DECODE(((uint32_t *)btp)[1]));
1391 break;
1392
1393 case KMERR_BADBASE:
1394 printf("bad free: free address (%p) != alloc address (%p)\n",
1395 bufarg, buf);
1396 break;
1397 }
1398
1399 printf("buffer=%p bufctl=%p cache: %s\n",
1400 bufarg, (void *)bcp, cparg->cache_name);
1401
1402 if (bcp != NULL && (cp->cache_flags & KMF_AUDIT) &&
1403 error != KMERR_BADBUFCTL) {
1404 int d;
1405 timestruc_t ts;
1406 kmem_bufctl_audit_t *bcap = (kmem_bufctl_audit_t *)bcp;
1407
1408 hrt2ts(kmem_panic_info.kmp_timestamp - bcap->bc_timestamp, &ts);
1409 printf("previous transaction on buffer %p:\n", buf);
1410 printf("thread=%p time=T-%ld.%09ld slab=%p cache: %s\n",
1411 (void *)bcap->bc_thread, ts.tv_sec, ts.tv_nsec,
1412 (void *)sp, cp->cache_name);
1413 for (d = 0; d < MIN(bcap->bc_depth, KMEM_STACK_DEPTH); d++) {
1414 ulong_t off;
1415 char *sym = kobj_getsymname(bcap->bc_stack[d], &off);
1416 printf("%s+%lx\n", sym ? sym : "?", off);
1417 }
1418 }
1419 if (kmem_panic > 0)
1420 panic("kernel heap corruption detected");
1421 if (kmem_panic == 0)
1422 debug_enter(NULL);
1423 kmem_logging = 1; /* resume logging */
1424 }
1425
1426 static kmem_log_header_t *
kmem_log_init(size_t logsize)1427 kmem_log_init(size_t logsize)
1428 {
1429 kmem_log_header_t *lhp;
1430 int nchunks = 4 * max_ncpus;
1431 size_t lhsize = (size_t)&((kmem_log_header_t *)0)->lh_cpu[max_ncpus];
1432 int i;
1433
1434 /*
1435 * Make sure that lhp->lh_cpu[] is nicely aligned
1436 * to prevent false sharing of cache lines.
1437 */
1438 lhsize = P2ROUNDUP(lhsize, KMEM_ALIGN);
1439 lhp = vmem_xalloc(kmem_log_arena, lhsize, 64, P2NPHASE(lhsize, 64), 0,
1440 NULL, NULL, VM_SLEEP);
1441 bzero(lhp, lhsize);
1442
1443 mutex_init(&lhp->lh_lock, NULL, MUTEX_DEFAULT, NULL);
1444 lhp->lh_nchunks = nchunks;
1445 lhp->lh_chunksize = P2ROUNDUP(logsize / nchunks + 1, PAGESIZE);
1446 lhp->lh_base = vmem_alloc(kmem_log_arena,
1447 lhp->lh_chunksize * nchunks, VM_SLEEP);
1448 lhp->lh_free = vmem_alloc(kmem_log_arena,
1449 nchunks * sizeof (int), VM_SLEEP);
1450 bzero(lhp->lh_base, lhp->lh_chunksize * nchunks);
1451
1452 for (i = 0; i < max_ncpus; i++) {
1453 kmem_cpu_log_header_t *clhp = &lhp->lh_cpu[i];
1454 mutex_init(&clhp->clh_lock, NULL, MUTEX_DEFAULT, NULL);
1455 clhp->clh_chunk = i;
1456 }
1457
1458 for (i = max_ncpus; i < nchunks; i++)
1459 lhp->lh_free[i] = i;
1460
1461 lhp->lh_head = max_ncpus;
1462 lhp->lh_tail = 0;
1463
1464 return (lhp);
1465 }
1466
1467 static void *
kmem_log_enter(kmem_log_header_t * lhp,void * data,size_t size)1468 kmem_log_enter(kmem_log_header_t *lhp, void *data, size_t size)
1469 {
1470 void *logspace;
1471 kmem_cpu_log_header_t *clhp = &lhp->lh_cpu[CPU->cpu_seqid];
1472
1473 if (lhp == NULL || kmem_logging == 0 || panicstr)
1474 return (NULL);
1475
1476 mutex_enter(&clhp->clh_lock);
1477 clhp->clh_hits++;
1478 if (size > clhp->clh_avail) {
1479 mutex_enter(&lhp->lh_lock);
1480 lhp->lh_hits++;
1481 lhp->lh_free[lhp->lh_tail] = clhp->clh_chunk;
1482 lhp->lh_tail = (lhp->lh_tail + 1) % lhp->lh_nchunks;
1483 clhp->clh_chunk = lhp->lh_free[lhp->lh_head];
1484 lhp->lh_head = (lhp->lh_head + 1) % lhp->lh_nchunks;
1485 clhp->clh_current = lhp->lh_base +
1486 clhp->clh_chunk * lhp->lh_chunksize;
1487 clhp->clh_avail = lhp->lh_chunksize;
1488 if (size > lhp->lh_chunksize)
1489 size = lhp->lh_chunksize;
1490 mutex_exit(&lhp->lh_lock);
1491 }
1492 logspace = clhp->clh_current;
1493 clhp->clh_current += size;
1494 clhp->clh_avail -= size;
1495 bcopy(data, logspace, size);
1496 mutex_exit(&clhp->clh_lock);
1497 return (logspace);
1498 }
1499
1500 #define KMEM_AUDIT(lp, cp, bcp) \
1501 { \
1502 kmem_bufctl_audit_t *_bcp = (kmem_bufctl_audit_t *)(bcp); \
1503 _bcp->bc_timestamp = gethrtime(); \
1504 _bcp->bc_thread = curthread; \
1505 _bcp->bc_depth = getpcstack(_bcp->bc_stack, KMEM_STACK_DEPTH); \
1506 _bcp->bc_lastlog = kmem_log_enter((lp), _bcp, sizeof (*_bcp)); \
1507 }
1508
1509 static void
kmem_log_event(kmem_log_header_t * lp,kmem_cache_t * cp,kmem_slab_t * sp,void * addr)1510 kmem_log_event(kmem_log_header_t *lp, kmem_cache_t *cp,
1511 kmem_slab_t *sp, void *addr)
1512 {
1513 kmem_bufctl_audit_t bca;
1514
1515 bzero(&bca, sizeof (kmem_bufctl_audit_t));
1516 bca.bc_addr = addr;
1517 bca.bc_slab = sp;
1518 bca.bc_cache = cp;
1519 KMEM_AUDIT(lp, cp, &bca);
1520 }
1521
1522 /*
1523 * Create a new slab for cache cp.
1524 */
1525 static kmem_slab_t *
kmem_slab_create(kmem_cache_t * cp,int kmflag)1526 kmem_slab_create(kmem_cache_t *cp, int kmflag)
1527 {
1528 size_t slabsize = cp->cache_slabsize;
1529 size_t chunksize = cp->cache_chunksize;
1530 int cache_flags = cp->cache_flags;
1531 size_t color, chunks;
1532 char *buf, *slab;
1533 kmem_slab_t *sp;
1534 kmem_bufctl_t *bcp;
1535 vmem_t *vmp = cp->cache_arena;
1536
1537 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1538
1539 color = cp->cache_color + cp->cache_align;
1540 if (color > cp->cache_maxcolor)
1541 color = cp->cache_mincolor;
1542 cp->cache_color = color;
1543
1544 slab = vmem_alloc(vmp, slabsize, kmflag & KM_VMFLAGS);
1545
1546 if (slab == NULL)
1547 goto vmem_alloc_failure;
1548
1549 ASSERT(P2PHASE((uintptr_t)slab, vmp->vm_quantum) == 0);
1550
1551 /*
1552 * Reverify what was already checked in kmem_cache_set_move(), since the
1553 * consolidator depends (for correctness) on slabs being initialized
1554 * with the 0xbaddcafe memory pattern (setting a low order bit usable by
1555 * clients to distinguish uninitialized memory from known objects).
1556 */
1557 ASSERT((cp->cache_move == NULL) || !(cp->cache_cflags & KMC_NOTOUCH));
1558 if (!(cp->cache_cflags & KMC_NOTOUCH))
1559 copy_pattern(KMEM_UNINITIALIZED_PATTERN, slab, slabsize);
1560
1561 if (cache_flags & KMF_HASH) {
1562 if ((sp = kmem_cache_alloc(kmem_slab_cache, kmflag)) == NULL)
1563 goto slab_alloc_failure;
1564 chunks = (slabsize - color) / chunksize;
1565 } else {
1566 sp = KMEM_SLAB(cp, slab);
1567 chunks = (slabsize - sizeof (kmem_slab_t) - color) / chunksize;
1568 }
1569
1570 sp->slab_cache = cp;
1571 sp->slab_head = NULL;
1572 sp->slab_refcnt = 0;
1573 sp->slab_base = buf = slab + color;
1574 sp->slab_chunks = chunks;
1575 sp->slab_stuck_offset = (uint32_t)-1;
1576 sp->slab_later_count = 0;
1577 sp->slab_flags = 0;
1578
1579 ASSERT(chunks > 0);
1580 while (chunks-- != 0) {
1581 if (cache_flags & KMF_HASH) {
1582 bcp = kmem_cache_alloc(cp->cache_bufctl_cache, kmflag);
1583 if (bcp == NULL)
1584 goto bufctl_alloc_failure;
1585 if (cache_flags & KMF_AUDIT) {
1586 kmem_bufctl_audit_t *bcap =
1587 (kmem_bufctl_audit_t *)bcp;
1588 bzero(bcap, sizeof (kmem_bufctl_audit_t));
1589 bcap->bc_cache = cp;
1590 }
1591 bcp->bc_addr = buf;
1592 bcp->bc_slab = sp;
1593 } else {
1594 bcp = KMEM_BUFCTL(cp, buf);
1595 }
1596 if (cache_flags & KMF_BUFTAG) {
1597 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1598 btp->bt_redzone = KMEM_REDZONE_PATTERN;
1599 btp->bt_bufctl = bcp;
1600 btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1601 if (cache_flags & KMF_DEADBEEF) {
1602 copy_pattern(KMEM_FREE_PATTERN, buf,
1603 cp->cache_verify);
1604 }
1605 }
1606 bcp->bc_next = sp->slab_head;
1607 sp->slab_head = bcp;
1608 buf += chunksize;
1609 }
1610
1611 kmem_log_event(kmem_slab_log, cp, sp, slab);
1612
1613 return (sp);
1614
1615 bufctl_alloc_failure:
1616
1617 while ((bcp = sp->slab_head) != NULL) {
1618 sp->slab_head = bcp->bc_next;
1619 kmem_cache_free(cp->cache_bufctl_cache, bcp);
1620 }
1621 kmem_cache_free(kmem_slab_cache, sp);
1622
1623 slab_alloc_failure:
1624
1625 vmem_free(vmp, slab, slabsize);
1626
1627 vmem_alloc_failure:
1628
1629 kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1630 atomic_inc_64(&cp->cache_alloc_fail);
1631
1632 return (NULL);
1633 }
1634
1635 /*
1636 * Destroy a slab.
1637 */
1638 static void
kmem_slab_destroy(kmem_cache_t * cp,kmem_slab_t * sp)1639 kmem_slab_destroy(kmem_cache_t *cp, kmem_slab_t *sp)
1640 {
1641 vmem_t *vmp = cp->cache_arena;
1642 void *slab = (void *)P2ALIGN((uintptr_t)sp->slab_base, vmp->vm_quantum);
1643
1644 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1645 ASSERT(sp->slab_refcnt == 0);
1646
1647 if (cp->cache_flags & KMF_HASH) {
1648 kmem_bufctl_t *bcp;
1649 while ((bcp = sp->slab_head) != NULL) {
1650 sp->slab_head = bcp->bc_next;
1651 kmem_cache_free(cp->cache_bufctl_cache, bcp);
1652 }
1653 kmem_cache_free(kmem_slab_cache, sp);
1654 }
1655 vmem_free(vmp, slab, cp->cache_slabsize);
1656 }
1657
1658 static void *
kmem_slab_alloc_impl(kmem_cache_t * cp,kmem_slab_t * sp,boolean_t prefill)1659 kmem_slab_alloc_impl(kmem_cache_t *cp, kmem_slab_t *sp, boolean_t prefill)
1660 {
1661 kmem_bufctl_t *bcp, **hash_bucket;
1662 void *buf;
1663 boolean_t new_slab = (sp->slab_refcnt == 0);
1664
1665 ASSERT(MUTEX_HELD(&cp->cache_lock));
1666 /*
1667 * kmem_slab_alloc() drops cache_lock when it creates a new slab, so we
1668 * can't ASSERT(avl_is_empty(&cp->cache_partial_slabs)) here when the
1669 * slab is newly created.
1670 */
1671 ASSERT(new_slab || (KMEM_SLAB_IS_PARTIAL(sp) &&
1672 (sp == avl_first(&cp->cache_partial_slabs))));
1673 ASSERT(sp->slab_cache == cp);
1674
1675 cp->cache_slab_alloc++;
1676 cp->cache_bufslab--;
1677 sp->slab_refcnt++;
1678
1679 bcp = sp->slab_head;
1680 sp->slab_head = bcp->bc_next;
1681
1682 if (cp->cache_flags & KMF_HASH) {
1683 /*
1684 * Add buffer to allocated-address hash table.
1685 */
1686 buf = bcp->bc_addr;
1687 hash_bucket = KMEM_HASH(cp, buf);
1688 bcp->bc_next = *hash_bucket;
1689 *hash_bucket = bcp;
1690 if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1691 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1692 }
1693 } else {
1694 buf = KMEM_BUF(cp, bcp);
1695 }
1696
1697 ASSERT(KMEM_SLAB_MEMBER(sp, buf));
1698
1699 if (sp->slab_head == NULL) {
1700 ASSERT(KMEM_SLAB_IS_ALL_USED(sp));
1701 if (new_slab) {
1702 ASSERT(sp->slab_chunks == 1);
1703 } else {
1704 ASSERT(sp->slab_chunks > 1); /* the slab was partial */
1705 avl_remove(&cp->cache_partial_slabs, sp);
1706 sp->slab_later_count = 0; /* clear history */
1707 sp->slab_flags &= ~KMEM_SLAB_NOMOVE;
1708 sp->slab_stuck_offset = (uint32_t)-1;
1709 }
1710 list_insert_head(&cp->cache_complete_slabs, sp);
1711 cp->cache_complete_slab_count++;
1712 return (buf);
1713 }
1714
1715 ASSERT(KMEM_SLAB_IS_PARTIAL(sp));
1716 /*
1717 * Peek to see if the magazine layer is enabled before
1718 * we prefill. We're not holding the cpu cache lock,
1719 * so the peek could be wrong, but there's no harm in it.
1720 */
1721 if (new_slab && prefill && (cp->cache_flags & KMF_PREFILL) &&
1722 (KMEM_CPU_CACHE(cp)->cc_magsize != 0)) {
1723 kmem_slab_prefill(cp, sp);
1724 return (buf);
1725 }
1726
1727 if (new_slab) {
1728 avl_add(&cp->cache_partial_slabs, sp);
1729 return (buf);
1730 }
1731
1732 /*
1733 * The slab is now more allocated than it was, so the
1734 * order remains unchanged.
1735 */
1736 ASSERT(!avl_update(&cp->cache_partial_slabs, sp));
1737 return (buf);
1738 }
1739
1740 /*
1741 * Allocate a raw (unconstructed) buffer from cp's slab layer.
1742 */
1743 static void *
kmem_slab_alloc(kmem_cache_t * cp,int kmflag)1744 kmem_slab_alloc(kmem_cache_t *cp, int kmflag)
1745 {
1746 kmem_slab_t *sp;
1747 void *buf;
1748 boolean_t test_destructor;
1749
1750 mutex_enter(&cp->cache_lock);
1751 test_destructor = (cp->cache_slab_alloc == 0);
1752 sp = avl_first(&cp->cache_partial_slabs);
1753 if (sp == NULL) {
1754 ASSERT(cp->cache_bufslab == 0);
1755
1756 /*
1757 * The freelist is empty. Create a new slab.
1758 */
1759 mutex_exit(&cp->cache_lock);
1760 if ((sp = kmem_slab_create(cp, kmflag)) == NULL) {
1761 return (NULL);
1762 }
1763 mutex_enter(&cp->cache_lock);
1764 cp->cache_slab_create++;
1765 if ((cp->cache_buftotal += sp->slab_chunks) > cp->cache_bufmax)
1766 cp->cache_bufmax = cp->cache_buftotal;
1767 cp->cache_bufslab += sp->slab_chunks;
1768 }
1769
1770 buf = kmem_slab_alloc_impl(cp, sp, B_TRUE);
1771 ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1772 (cp->cache_complete_slab_count +
1773 avl_numnodes(&cp->cache_partial_slabs) +
1774 (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1775 mutex_exit(&cp->cache_lock);
1776
1777 if (test_destructor && cp->cache_destructor != NULL) {
1778 /*
1779 * On the first kmem_slab_alloc(), assert that it is valid to
1780 * call the destructor on a newly constructed object without any
1781 * client involvement.
1782 */
1783 if ((cp->cache_constructor == NULL) ||
1784 cp->cache_constructor(buf, cp->cache_private,
1785 kmflag) == 0) {
1786 cp->cache_destructor(buf, cp->cache_private);
1787 }
1788 copy_pattern(KMEM_UNINITIALIZED_PATTERN, buf,
1789 cp->cache_bufsize);
1790 if (cp->cache_flags & KMF_DEADBEEF) {
1791 copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1792 }
1793 }
1794
1795 return (buf);
1796 }
1797
1798 static void kmem_slab_move_yes(kmem_cache_t *, kmem_slab_t *, void *);
1799
1800 /*
1801 * Free a raw (unconstructed) buffer to cp's slab layer.
1802 */
1803 static void
kmem_slab_free(kmem_cache_t * cp,void * buf)1804 kmem_slab_free(kmem_cache_t *cp, void *buf)
1805 {
1806 kmem_slab_t *sp;
1807 kmem_bufctl_t *bcp, **prev_bcpp;
1808
1809 ASSERT(buf != NULL);
1810
1811 mutex_enter(&cp->cache_lock);
1812 cp->cache_slab_free++;
1813
1814 if (cp->cache_flags & KMF_HASH) {
1815 /*
1816 * Look up buffer in allocated-address hash table.
1817 */
1818 prev_bcpp = KMEM_HASH(cp, buf);
1819 while ((bcp = *prev_bcpp) != NULL) {
1820 if (bcp->bc_addr == buf) {
1821 *prev_bcpp = bcp->bc_next;
1822 sp = bcp->bc_slab;
1823 break;
1824 }
1825 cp->cache_lookup_depth++;
1826 prev_bcpp = &bcp->bc_next;
1827 }
1828 } else {
1829 bcp = KMEM_BUFCTL(cp, buf);
1830 sp = KMEM_SLAB(cp, buf);
1831 }
1832
1833 if (bcp == NULL || sp->slab_cache != cp || !KMEM_SLAB_MEMBER(sp, buf)) {
1834 mutex_exit(&cp->cache_lock);
1835 kmem_error(KMERR_BADADDR, cp, buf);
1836 return;
1837 }
1838
1839 if (KMEM_SLAB_OFFSET(sp, buf) == sp->slab_stuck_offset) {
1840 /*
1841 * If this is the buffer that prevented the consolidator from
1842 * clearing the slab, we can reset the slab flags now that the
1843 * buffer is freed. (It makes sense to do this in
1844 * kmem_cache_free(), where the client gives up ownership of the
1845 * buffer, but on the hot path the test is too expensive.)
1846 */
1847 kmem_slab_move_yes(cp, sp, buf);
1848 }
1849
1850 if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1851 if (cp->cache_flags & KMF_CONTENTS)
1852 ((kmem_bufctl_audit_t *)bcp)->bc_contents =
1853 kmem_log_enter(kmem_content_log, buf,
1854 cp->cache_contents);
1855 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1856 }
1857
1858 bcp->bc_next = sp->slab_head;
1859 sp->slab_head = bcp;
1860
1861 cp->cache_bufslab++;
1862 ASSERT(sp->slab_refcnt >= 1);
1863
1864 if (--sp->slab_refcnt == 0) {
1865 /*
1866 * There are no outstanding allocations from this slab,
1867 * so we can reclaim the memory.
1868 */
1869 if (sp->slab_chunks == 1) {
1870 list_remove(&cp->cache_complete_slabs, sp);
1871 cp->cache_complete_slab_count--;
1872 } else {
1873 avl_remove(&cp->cache_partial_slabs, sp);
1874 }
1875
1876 cp->cache_buftotal -= sp->slab_chunks;
1877 cp->cache_bufslab -= sp->slab_chunks;
1878 /*
1879 * Defer releasing the slab to the virtual memory subsystem
1880 * while there is a pending move callback, since we guarantee
1881 * that buffers passed to the move callback have only been
1882 * touched by kmem or by the client itself. Since the memory
1883 * patterns baddcafe (uninitialized) and deadbeef (freed) both
1884 * set at least one of the two lowest order bits, the client can
1885 * test those bits in the move callback to determine whether or
1886 * not it knows about the buffer (assuming that the client also
1887 * sets one of those low order bits whenever it frees a buffer).
1888 */
1889 if (cp->cache_defrag == NULL ||
1890 (avl_is_empty(&cp->cache_defrag->kmd_moves_pending) &&
1891 !(sp->slab_flags & KMEM_SLAB_MOVE_PENDING))) {
1892 cp->cache_slab_destroy++;
1893 mutex_exit(&cp->cache_lock);
1894 kmem_slab_destroy(cp, sp);
1895 } else {
1896 list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
1897 /*
1898 * Slabs are inserted at both ends of the deadlist to
1899 * distinguish between slabs freed while move callbacks
1900 * are pending (list head) and a slab freed while the
1901 * lock is dropped in kmem_move_buffers() (list tail) so
1902 * that in both cases slab_destroy() is called from the
1903 * right context.
1904 */
1905 if (sp->slab_flags & KMEM_SLAB_MOVE_PENDING) {
1906 list_insert_tail(deadlist, sp);
1907 } else {
1908 list_insert_head(deadlist, sp);
1909 }
1910 cp->cache_defrag->kmd_deadcount++;
1911 mutex_exit(&cp->cache_lock);
1912 }
1913 return;
1914 }
1915
1916 if (bcp->bc_next == NULL) {
1917 /* Transition the slab from completely allocated to partial. */
1918 ASSERT(sp->slab_refcnt == (sp->slab_chunks - 1));
1919 ASSERT(sp->slab_chunks > 1);
1920 list_remove(&cp->cache_complete_slabs, sp);
1921 cp->cache_complete_slab_count--;
1922 avl_add(&cp->cache_partial_slabs, sp);
1923 } else {
1924 #ifdef DEBUG
1925 if (avl_update_gt(&cp->cache_partial_slabs, sp)) {
1926 KMEM_STAT_ADD(kmem_move_stats.kms_avl_update);
1927 } else {
1928 KMEM_STAT_ADD(kmem_move_stats.kms_avl_noupdate);
1929 }
1930 #else
1931 (void) avl_update_gt(&cp->cache_partial_slabs, sp);
1932 #endif
1933 }
1934
1935 ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1936 (cp->cache_complete_slab_count +
1937 avl_numnodes(&cp->cache_partial_slabs) +
1938 (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1939 mutex_exit(&cp->cache_lock);
1940 }
1941
1942 /*
1943 * Return -1 if kmem_error, 1 if constructor fails, 0 if successful.
1944 */
1945 static int
kmem_cache_alloc_debug(kmem_cache_t * cp,void * buf,int kmflag,int construct,caddr_t caller)1946 kmem_cache_alloc_debug(kmem_cache_t *cp, void *buf, int kmflag, int construct,
1947 caddr_t caller)
1948 {
1949 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1950 kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
1951 uint32_t mtbf;
1952
1953 if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
1954 kmem_error(KMERR_BADBUFTAG, cp, buf);
1955 return (-1);
1956 }
1957
1958 btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_ALLOC;
1959
1960 if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
1961 kmem_error(KMERR_BADBUFCTL, cp, buf);
1962 return (-1);
1963 }
1964
1965 if (cp->cache_flags & KMF_DEADBEEF) {
1966 if (!construct && (cp->cache_flags & KMF_LITE)) {
1967 if (*(uint64_t *)buf != KMEM_FREE_PATTERN) {
1968 kmem_error(KMERR_MODIFIED, cp, buf);
1969 return (-1);
1970 }
1971 if (cp->cache_constructor != NULL)
1972 *(uint64_t *)buf = btp->bt_redzone;
1973 else
1974 *(uint64_t *)buf = KMEM_UNINITIALIZED_PATTERN;
1975 } else {
1976 construct = 1;
1977 if (verify_and_copy_pattern(KMEM_FREE_PATTERN,
1978 KMEM_UNINITIALIZED_PATTERN, buf,
1979 cp->cache_verify)) {
1980 kmem_error(KMERR_MODIFIED, cp, buf);
1981 return (-1);
1982 }
1983 }
1984 }
1985 btp->bt_redzone = KMEM_REDZONE_PATTERN;
1986
1987 if ((mtbf = kmem_mtbf | cp->cache_mtbf) != 0 &&
1988 gethrtime() % mtbf == 0 &&
1989 (kmflag & (KM_NOSLEEP | KM_PANIC)) == KM_NOSLEEP) {
1990 kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1991 if (!construct && cp->cache_destructor != NULL)
1992 cp->cache_destructor(buf, cp->cache_private);
1993 } else {
1994 mtbf = 0;
1995 }
1996
1997 if (mtbf || (construct && cp->cache_constructor != NULL &&
1998 cp->cache_constructor(buf, cp->cache_private, kmflag) != 0)) {
1999 atomic_inc_64(&cp->cache_alloc_fail);
2000 btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
2001 if (cp->cache_flags & KMF_DEADBEEF)
2002 copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
2003 kmem_slab_free(cp, buf);
2004 return (1);
2005 }
2006
2007 if (cp->cache_flags & KMF_AUDIT) {
2008 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
2009 }
2010
2011 if ((cp->cache_flags & KMF_LITE) &&
2012 !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
2013 KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
2014 }
2015
2016 return (0);
2017 }
2018
2019 static int
kmem_cache_free_debug(kmem_cache_t * cp,void * buf,caddr_t caller)2020 kmem_cache_free_debug(kmem_cache_t *cp, void *buf, caddr_t caller)
2021 {
2022 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2023 kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
2024 kmem_slab_t *sp;
2025
2026 if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_ALLOC)) {
2027 if (btp->bt_bxstat == ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
2028 kmem_error(KMERR_DUPFREE, cp, buf);
2029 return (-1);
2030 }
2031 sp = kmem_findslab(cp, buf);
2032 if (sp == NULL || sp->slab_cache != cp)
2033 kmem_error(KMERR_BADADDR, cp, buf);
2034 else
2035 kmem_error(KMERR_REDZONE, cp, buf);
2036 return (-1);
2037 }
2038
2039 btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
2040
2041 if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
2042 kmem_error(KMERR_BADBUFCTL, cp, buf);
2043 return (-1);
2044 }
2045
2046 if (btp->bt_redzone != KMEM_REDZONE_PATTERN) {
2047 kmem_error(KMERR_REDZONE, cp, buf);
2048 return (-1);
2049 }
2050
2051 if (cp->cache_flags & KMF_AUDIT) {
2052 if (cp->cache_flags & KMF_CONTENTS)
2053 bcp->bc_contents = kmem_log_enter(kmem_content_log,
2054 buf, cp->cache_contents);
2055 KMEM_AUDIT(kmem_transaction_log, cp, bcp);
2056 }
2057
2058 if ((cp->cache_flags & KMF_LITE) &&
2059 !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
2060 KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
2061 }
2062
2063 if (cp->cache_flags & KMF_DEADBEEF) {
2064 if (cp->cache_flags & KMF_LITE)
2065 btp->bt_redzone = *(uint64_t *)buf;
2066 else if (cp->cache_destructor != NULL)
2067 cp->cache_destructor(buf, cp->cache_private);
2068
2069 copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
2070 }
2071
2072 return (0);
2073 }
2074
2075 /*
2076 * Free each object in magazine mp to cp's slab layer, and free mp itself.
2077 */
2078 static void
kmem_magazine_destroy(kmem_cache_t * cp,kmem_magazine_t * mp,int nrounds)2079 kmem_magazine_destroy(kmem_cache_t *cp, kmem_magazine_t *mp, int nrounds)
2080 {
2081 int round;
2082
2083 ASSERT(!list_link_active(&cp->cache_link) ||
2084 taskq_member(kmem_taskq, curthread));
2085
2086 for (round = 0; round < nrounds; round++) {
2087 void *buf = mp->mag_round[round];
2088
2089 if (cp->cache_flags & KMF_DEADBEEF) {
2090 if (verify_pattern(KMEM_FREE_PATTERN, buf,
2091 cp->cache_verify) != NULL) {
2092 kmem_error(KMERR_MODIFIED, cp, buf);
2093 continue;
2094 }
2095 if ((cp->cache_flags & KMF_LITE) &&
2096 cp->cache_destructor != NULL) {
2097 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2098 *(uint64_t *)buf = btp->bt_redzone;
2099 cp->cache_destructor(buf, cp->cache_private);
2100 *(uint64_t *)buf = KMEM_FREE_PATTERN;
2101 }
2102 } else if (cp->cache_destructor != NULL) {
2103 cp->cache_destructor(buf, cp->cache_private);
2104 }
2105
2106 kmem_slab_free(cp, buf);
2107 }
2108 ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2109 kmem_cache_free(cp->cache_magtype->mt_cache, mp);
2110 }
2111
2112 /*
2113 * Allocate a magazine from the depot.
2114 */
2115 static kmem_magazine_t *
kmem_depot_alloc(kmem_cache_t * cp,kmem_maglist_t * mlp)2116 kmem_depot_alloc(kmem_cache_t *cp, kmem_maglist_t *mlp)
2117 {
2118 kmem_magazine_t *mp;
2119
2120 /*
2121 * If we can't get the depot lock without contention,
2122 * update our contention count. We use the depot
2123 * contention rate to determine whether we need to
2124 * increase the magazine size for better scalability.
2125 */
2126 if (!mutex_tryenter(&cp->cache_depot_lock)) {
2127 mutex_enter(&cp->cache_depot_lock);
2128 cp->cache_depot_contention++;
2129 }
2130
2131 if ((mp = mlp->ml_list) != NULL) {
2132 ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2133 mlp->ml_list = mp->mag_next;
2134 if (--mlp->ml_total < mlp->ml_min)
2135 mlp->ml_min = mlp->ml_total;
2136 mlp->ml_alloc++;
2137 }
2138
2139 mutex_exit(&cp->cache_depot_lock);
2140
2141 return (mp);
2142 }
2143
2144 /*
2145 * Free a magazine to the depot.
2146 */
2147 static void
kmem_depot_free(kmem_cache_t * cp,kmem_maglist_t * mlp,kmem_magazine_t * mp)2148 kmem_depot_free(kmem_cache_t *cp, kmem_maglist_t *mlp, kmem_magazine_t *mp)
2149 {
2150 mutex_enter(&cp->cache_depot_lock);
2151 ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2152 mp->mag_next = mlp->ml_list;
2153 mlp->ml_list = mp;
2154 mlp->ml_total++;
2155 mutex_exit(&cp->cache_depot_lock);
2156 }
2157
2158 /*
2159 * Update the working set statistics for cp's depot.
2160 */
2161 static void
kmem_depot_ws_update(kmem_cache_t * cp)2162 kmem_depot_ws_update(kmem_cache_t *cp)
2163 {
2164 mutex_enter(&cp->cache_depot_lock);
2165 cp->cache_full.ml_reaplimit = cp->cache_full.ml_min;
2166 cp->cache_full.ml_min = cp->cache_full.ml_total;
2167 cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_min;
2168 cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2169 mutex_exit(&cp->cache_depot_lock);
2170 }
2171
2172 /*
2173 * Set the working set statistics for cp's depot to zero. (Everything is
2174 * eligible for reaping.)
2175 */
2176 static void
kmem_depot_ws_zero(kmem_cache_t * cp)2177 kmem_depot_ws_zero(kmem_cache_t *cp)
2178 {
2179 mutex_enter(&cp->cache_depot_lock);
2180 cp->cache_full.ml_reaplimit = cp->cache_full.ml_total;
2181 cp->cache_full.ml_min = cp->cache_full.ml_total;
2182 cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_total;
2183 cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2184 mutex_exit(&cp->cache_depot_lock);
2185 }
2186
2187 /*
2188 * Reap all magazines that have fallen out of the depot's working set.
2189 */
2190 static void
kmem_depot_ws_reap(kmem_cache_t * cp)2191 kmem_depot_ws_reap(kmem_cache_t *cp)
2192 {
2193 long reap;
2194 kmem_magazine_t *mp;
2195
2196 ASSERT(!list_link_active(&cp->cache_link) ||
2197 taskq_member(kmem_taskq, curthread));
2198
2199 reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
2200 while (reap-- && (mp = kmem_depot_alloc(cp, &cp->cache_full)) != NULL)
2201 kmem_magazine_destroy(cp, mp, cp->cache_magtype->mt_magsize);
2202
2203 reap = MIN(cp->cache_empty.ml_reaplimit, cp->cache_empty.ml_min);
2204 while (reap-- && (mp = kmem_depot_alloc(cp, &cp->cache_empty)) != NULL)
2205 kmem_magazine_destroy(cp, mp, 0);
2206 }
2207
2208 static void
kmem_cpu_reload(kmem_cpu_cache_t * ccp,kmem_magazine_t * mp,int rounds)2209 kmem_cpu_reload(kmem_cpu_cache_t *ccp, kmem_magazine_t *mp, int rounds)
2210 {
2211 ASSERT((ccp->cc_loaded == NULL && ccp->cc_rounds == -1) ||
2212 (ccp->cc_loaded && ccp->cc_rounds + rounds == ccp->cc_magsize));
2213 ASSERT(ccp->cc_magsize > 0);
2214
2215 ccp->cc_ploaded = ccp->cc_loaded;
2216 ccp->cc_prounds = ccp->cc_rounds;
2217 ccp->cc_loaded = mp;
2218 ccp->cc_rounds = rounds;
2219 }
2220
2221 /*
2222 * Intercept kmem alloc/free calls during crash dump in order to avoid
2223 * changing kmem state while memory is being saved to the dump device.
2224 * Otherwise, ::kmem_verify will report "corrupt buffers". Note that
2225 * there are no locks because only one CPU calls kmem during a crash
2226 * dump. To enable this feature, first create the associated vmem
2227 * arena with VMC_DUMPSAFE.
2228 */
2229 static void *kmem_dump_start; /* start of pre-reserved heap */
2230 static void *kmem_dump_end; /* end of heap area */
2231 static void *kmem_dump_curr; /* current free heap pointer */
2232 static size_t kmem_dump_size; /* size of heap area */
2233
2234 /* append to each buf created in the pre-reserved heap */
2235 typedef struct kmem_dumpctl {
2236 void *kdc_next; /* cache dump free list linkage */
2237 } kmem_dumpctl_t;
2238
2239 #define KMEM_DUMPCTL(cp, buf) \
2240 ((kmem_dumpctl_t *)P2ROUNDUP((uintptr_t)(buf) + (cp)->cache_bufsize, \
2241 sizeof (void *)))
2242
2243 /* set non zero for full report */
2244 uint_t kmem_dump_verbose = 0;
2245
2246 /* stats for overize heap */
2247 uint_t kmem_dump_oversize_allocs = 0;
2248 uint_t kmem_dump_oversize_max = 0;
2249
2250 static void
kmem_dumppr(char ** pp,char * e,const char * format,...)2251 kmem_dumppr(char **pp, char *e, const char *format, ...)
2252 {
2253 char *p = *pp;
2254
2255 if (p < e) {
2256 int n;
2257 va_list ap;
2258
2259 va_start(ap, format);
2260 n = vsnprintf(p, e - p, format, ap);
2261 va_end(ap);
2262 *pp = p + n;
2263 }
2264 }
2265
2266 /*
2267 * Called when dumpadm(1M) configures dump parameters.
2268 */
2269 void
kmem_dump_init(size_t size)2270 kmem_dump_init(size_t size)
2271 {
2272 /* Our caller ensures size is always set. */
2273 ASSERT3U(size, >, 0);
2274
2275 if (kmem_dump_start != NULL)
2276 kmem_free(kmem_dump_start, kmem_dump_size);
2277
2278 kmem_dump_start = kmem_alloc(size, KM_SLEEP);
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 }
2284
2285 /*
2286 * Set flag for each kmem_cache_t if is safe to use alternate dump
2287 * memory. Called just before panic crash dump starts. Set the flag
2288 * for the calling CPU.
2289 */
2290 void
kmem_dump_begin(void)2291 kmem_dump_begin(void)
2292 {
2293 kmem_cache_t *cp;
2294
2295 ASSERT(panicstr != NULL);
2296
2297 for (cp = list_head(&kmem_caches); cp != NULL;
2298 cp = list_next(&kmem_caches, cp)) {
2299 kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2300
2301 if (cp->cache_arena->vm_cflags & VMC_DUMPSAFE) {
2302 cp->cache_flags |= KMF_DUMPDIVERT;
2303 ccp->cc_flags |= KMF_DUMPDIVERT;
2304 ccp->cc_dump_rounds = ccp->cc_rounds;
2305 ccp->cc_dump_prounds = ccp->cc_prounds;
2306 ccp->cc_rounds = ccp->cc_prounds = -1;
2307 } else {
2308 cp->cache_flags |= KMF_DUMPUNSAFE;
2309 ccp->cc_flags |= KMF_DUMPUNSAFE;
2310 }
2311 }
2312 }
2313
2314 /*
2315 * finished dump intercept
2316 * print any warnings on the console
2317 * return verbose information to dumpsys() in the given buffer
2318 */
2319 size_t
kmem_dump_finish(char * buf,size_t size)2320 kmem_dump_finish(char *buf, size_t size)
2321 {
2322 int percent = 0;
2323 size_t used;
2324 char *e = buf + size;
2325 char *p = buf;
2326
2327 if (kmem_dump_curr == kmem_dump_end) {
2328 cmn_err(CE_WARN, "exceeded kmem_dump space of %lu "
2329 "bytes: kmem state in dump may be inconsistent",
2330 kmem_dump_size);
2331 }
2332
2333 if (kmem_dump_verbose == 0)
2334 return (0);
2335
2336 used = (char *)kmem_dump_curr - (char *)kmem_dump_start;
2337 percent = (used * 100) / kmem_dump_size;
2338
2339 kmem_dumppr(&p, e, "%% heap used,%d\n", percent);
2340 kmem_dumppr(&p, e, "used bytes,%ld\n", used);
2341 kmem_dumppr(&p, e, "heap size,%ld\n", kmem_dump_size);
2342 kmem_dumppr(&p, e, "Oversize allocs,%d\n",
2343 kmem_dump_oversize_allocs);
2344 kmem_dumppr(&p, e, "Oversize max size,%ld\n",
2345 kmem_dump_oversize_max);
2346
2347 /* return buffer size used */
2348 if (p < e)
2349 bzero(p, e - p);
2350 return (p - buf);
2351 }
2352
2353 /*
2354 * Allocate a constructed object from alternate dump memory.
2355 */
2356 void *
kmem_cache_alloc_dump(kmem_cache_t * cp,int kmflag)2357 kmem_cache_alloc_dump(kmem_cache_t *cp, int kmflag)
2358 {
2359 void *buf;
2360 void *curr;
2361 char *bufend;
2362
2363 /* return a constructed object */
2364 if ((buf = cp->cache_dump.kd_freelist) != NULL) {
2365 cp->cache_dump.kd_freelist = KMEM_DUMPCTL(cp, buf)->kdc_next;
2366 return (buf);
2367 }
2368
2369 /* create a new constructed object */
2370 curr = kmem_dump_curr;
2371 buf = (void *)P2ROUNDUP((uintptr_t)curr, cp->cache_align);
2372 bufend = (char *)KMEM_DUMPCTL(cp, buf) + sizeof (kmem_dumpctl_t);
2373
2374 /* hat layer objects cannot cross a page boundary */
2375 if (cp->cache_align < PAGESIZE) {
2376 char *page = (char *)P2ROUNDUP((uintptr_t)buf, PAGESIZE);
2377 if (bufend > page) {
2378 bufend += page - (char *)buf;
2379 buf = (void *)page;
2380 }
2381 }
2382
2383 /* fall back to normal alloc if reserved area is used up */
2384 if (bufend > (char *)kmem_dump_end) {
2385 kmem_dump_curr = kmem_dump_end;
2386 cp->cache_dump.kd_alloc_fails++;
2387 return (NULL);
2388 }
2389
2390 /*
2391 * Must advance curr pointer before calling a constructor that
2392 * may also allocate memory.
2393 */
2394 kmem_dump_curr = bufend;
2395
2396 /* run constructor */
2397 if (cp->cache_constructor != NULL &&
2398 cp->cache_constructor(buf, cp->cache_private, kmflag)
2399 != 0) {
2400 #ifdef DEBUG
2401 printf("name='%s' cache=0x%p: kmem cache constructor failed\n",
2402 cp->cache_name, (void *)cp);
2403 #endif
2404 /* reset curr pointer iff no allocs were done */
2405 if (kmem_dump_curr == bufend)
2406 kmem_dump_curr = curr;
2407
2408 cp->cache_dump.kd_alloc_fails++;
2409 /* fall back to normal alloc if the constructor fails */
2410 return (NULL);
2411 }
2412
2413 return (buf);
2414 }
2415
2416 /*
2417 * Free a constructed object in alternate dump memory.
2418 */
2419 int
kmem_cache_free_dump(kmem_cache_t * cp,void * buf)2420 kmem_cache_free_dump(kmem_cache_t *cp, void *buf)
2421 {
2422 /* save constructed buffers for next time */
2423 if ((char *)buf >= (char *)kmem_dump_start &&
2424 (char *)buf < (char *)kmem_dump_end) {
2425 KMEM_DUMPCTL(cp, buf)->kdc_next = cp->cache_dump.kd_freelist;
2426 cp->cache_dump.kd_freelist = buf;
2427 return (0);
2428 }
2429
2430 /* just drop buffers that were allocated before dump started */
2431 if (kmem_dump_curr < kmem_dump_end)
2432 return (0);
2433
2434 /* fall back to normal free if reserved area is used up */
2435 return (1);
2436 }
2437
2438 /*
2439 * Allocate a constructed object from cache cp.
2440 */
2441 void *
kmem_cache_alloc(kmem_cache_t * cp,int kmflag)2442 kmem_cache_alloc(kmem_cache_t *cp, int kmflag)
2443 {
2444 kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2445 kmem_magazine_t *fmp;
2446 void *buf;
2447
2448 mutex_enter(&ccp->cc_lock);
2449 for (;;) {
2450 /*
2451 * If there's an object available in the current CPU's
2452 * loaded magazine, just take it and return.
2453 */
2454 if (ccp->cc_rounds > 0) {
2455 buf = ccp->cc_loaded->mag_round[--ccp->cc_rounds];
2456 ccp->cc_alloc++;
2457 mutex_exit(&ccp->cc_lock);
2458 if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPUNSAFE)) {
2459 if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2460 ASSERT(!(ccp->cc_flags &
2461 KMF_DUMPDIVERT));
2462 cp->cache_dump.kd_unsafe++;
2463 }
2464 if ((ccp->cc_flags & KMF_BUFTAG) &&
2465 kmem_cache_alloc_debug(cp, buf, kmflag, 0,
2466 caller()) != 0) {
2467 if (kmflag & KM_NOSLEEP)
2468 return (NULL);
2469 mutex_enter(&ccp->cc_lock);
2470 continue;
2471 }
2472 }
2473 return (buf);
2474 }
2475
2476 /*
2477 * The loaded magazine is empty. If the previously loaded
2478 * magazine was full, exchange them and try again.
2479 */
2480 if (ccp->cc_prounds > 0) {
2481 kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2482 continue;
2483 }
2484
2485 /*
2486 * Return an alternate buffer at dump time to preserve
2487 * the heap.
2488 */
2489 if (ccp->cc_flags & (KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2490 if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2491 ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2492 /* log it so that we can warn about it */
2493 cp->cache_dump.kd_unsafe++;
2494 } else {
2495 if ((buf = kmem_cache_alloc_dump(cp, kmflag)) !=
2496 NULL) {
2497 mutex_exit(&ccp->cc_lock);
2498 return (buf);
2499 }
2500 break; /* fall back to slab layer */
2501 }
2502 }
2503
2504 /*
2505 * If the magazine layer is disabled, break out now.
2506 */
2507 if (ccp->cc_magsize == 0)
2508 break;
2509
2510 /*
2511 * Try to get a full magazine from the depot.
2512 */
2513 fmp = kmem_depot_alloc(cp, &cp->cache_full);
2514 if (fmp != NULL) {
2515 if (ccp->cc_ploaded != NULL)
2516 kmem_depot_free(cp, &cp->cache_empty,
2517 ccp->cc_ploaded);
2518 kmem_cpu_reload(ccp, fmp, ccp->cc_magsize);
2519 continue;
2520 }
2521
2522 /*
2523 * There are no full magazines in the depot,
2524 * so fall through to the slab layer.
2525 */
2526 break;
2527 }
2528 mutex_exit(&ccp->cc_lock);
2529
2530 /*
2531 * We couldn't allocate a constructed object from the magazine layer,
2532 * so get a raw buffer from the slab layer and apply its constructor.
2533 */
2534 buf = kmem_slab_alloc(cp, kmflag);
2535
2536 if (buf == NULL)
2537 return (NULL);
2538
2539 if (cp->cache_flags & KMF_BUFTAG) {
2540 /*
2541 * Make kmem_cache_alloc_debug() apply the constructor for us.
2542 */
2543 int rc = kmem_cache_alloc_debug(cp, buf, kmflag, 1, caller());
2544 if (rc != 0) {
2545 if (kmflag & KM_NOSLEEP)
2546 return (NULL);
2547 /*
2548 * kmem_cache_alloc_debug() detected corruption
2549 * but didn't panic (kmem_panic <= 0). We should not be
2550 * here because the constructor failed (indicated by a
2551 * return code of 1). Try again.
2552 */
2553 ASSERT(rc == -1);
2554 return (kmem_cache_alloc(cp, kmflag));
2555 }
2556 return (buf);
2557 }
2558
2559 if (cp->cache_constructor != NULL &&
2560 cp->cache_constructor(buf, cp->cache_private, kmflag) != 0) {
2561 atomic_inc_64(&cp->cache_alloc_fail);
2562 kmem_slab_free(cp, buf);
2563 return (NULL);
2564 }
2565
2566 return (buf);
2567 }
2568
2569 /*
2570 * The freed argument tells whether or not kmem_cache_free_debug() has already
2571 * been called so that we can avoid the duplicate free error. For example, a
2572 * buffer on a magazine has already been freed by the client but is still
2573 * constructed.
2574 */
2575 static void
kmem_slab_free_constructed(kmem_cache_t * cp,void * buf,boolean_t freed)2576 kmem_slab_free_constructed(kmem_cache_t *cp, void *buf, boolean_t freed)
2577 {
2578 if (!freed && (cp->cache_flags & KMF_BUFTAG))
2579 if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2580 return;
2581
2582 /*
2583 * Note that if KMF_DEADBEEF is in effect and KMF_LITE is not,
2584 * kmem_cache_free_debug() will have already applied the destructor.
2585 */
2586 if ((cp->cache_flags & (KMF_DEADBEEF | KMF_LITE)) != KMF_DEADBEEF &&
2587 cp->cache_destructor != NULL) {
2588 if (cp->cache_flags & KMF_DEADBEEF) { /* KMF_LITE implied */
2589 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2590 *(uint64_t *)buf = btp->bt_redzone;
2591 cp->cache_destructor(buf, cp->cache_private);
2592 *(uint64_t *)buf = KMEM_FREE_PATTERN;
2593 } else {
2594 cp->cache_destructor(buf, cp->cache_private);
2595 }
2596 }
2597
2598 kmem_slab_free(cp, buf);
2599 }
2600
2601 /*
2602 * Used when there's no room to free a buffer to the per-CPU cache.
2603 * Drops and re-acquires &ccp->cc_lock, and returns non-zero if the
2604 * caller should try freeing to the per-CPU cache again.
2605 * Note that we don't directly install the magazine in the cpu cache,
2606 * since its state may have changed wildly while the lock was dropped.
2607 */
2608 static int
kmem_cpucache_magazine_alloc(kmem_cpu_cache_t * ccp,kmem_cache_t * cp)2609 kmem_cpucache_magazine_alloc(kmem_cpu_cache_t *ccp, kmem_cache_t *cp)
2610 {
2611 kmem_magazine_t *emp;
2612 kmem_magtype_t *mtp;
2613
2614 ASSERT(MUTEX_HELD(&ccp->cc_lock));
2615 ASSERT(((uint_t)ccp->cc_rounds == ccp->cc_magsize ||
2616 ((uint_t)ccp->cc_rounds == -1)) &&
2617 ((uint_t)ccp->cc_prounds == ccp->cc_magsize ||
2618 ((uint_t)ccp->cc_prounds == -1)));
2619
2620 emp = kmem_depot_alloc(cp, &cp->cache_empty);
2621 if (emp != NULL) {
2622 if (ccp->cc_ploaded != NULL)
2623 kmem_depot_free(cp, &cp->cache_full,
2624 ccp->cc_ploaded);
2625 kmem_cpu_reload(ccp, emp, 0);
2626 return (1);
2627 }
2628 /*
2629 * There are no empty magazines in the depot,
2630 * so try to allocate a new one. We must drop all locks
2631 * across kmem_cache_alloc() because lower layers may
2632 * attempt to allocate from this cache.
2633 */
2634 mtp = cp->cache_magtype;
2635 mutex_exit(&ccp->cc_lock);
2636 emp = kmem_cache_alloc(mtp->mt_cache, KM_NOSLEEP);
2637 mutex_enter(&ccp->cc_lock);
2638
2639 if (emp != NULL) {
2640 /*
2641 * We successfully allocated an empty magazine.
2642 * However, we had to drop ccp->cc_lock to do it,
2643 * so the cache's magazine size may have changed.
2644 * If so, free the magazine and try again.
2645 */
2646 if (ccp->cc_magsize != mtp->mt_magsize) {
2647 mutex_exit(&ccp->cc_lock);
2648 kmem_cache_free(mtp->mt_cache, emp);
2649 mutex_enter(&ccp->cc_lock);
2650 return (1);
2651 }
2652
2653 /*
2654 * We got a magazine of the right size. Add it to
2655 * the depot and try the whole dance again.
2656 */
2657 kmem_depot_free(cp, &cp->cache_empty, emp);
2658 return (1);
2659 }
2660
2661 /*
2662 * We couldn't allocate an empty magazine,
2663 * so fall through to the slab layer.
2664 */
2665 return (0);
2666 }
2667
2668 /*
2669 * Free a constructed object to cache cp.
2670 */
2671 void
kmem_cache_free(kmem_cache_t * cp,void * buf)2672 kmem_cache_free(kmem_cache_t *cp, void *buf)
2673 {
2674 kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2675
2676 /*
2677 * The client must not free either of the buffers passed to the move
2678 * callback function.
2679 */
2680 ASSERT(cp->cache_defrag == NULL ||
2681 cp->cache_defrag->kmd_thread != curthread ||
2682 (buf != cp->cache_defrag->kmd_from_buf &&
2683 buf != cp->cache_defrag->kmd_to_buf));
2684
2685 if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2686 if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2687 ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2688 /* log it so that we can warn about it */
2689 cp->cache_dump.kd_unsafe++;
2690 } else if (KMEM_DUMPCC(ccp) && !kmem_cache_free_dump(cp, buf)) {
2691 return;
2692 }
2693 if (ccp->cc_flags & KMF_BUFTAG) {
2694 if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2695 return;
2696 }
2697 }
2698
2699 mutex_enter(&ccp->cc_lock);
2700 /*
2701 * Any changes to this logic should be reflected in kmem_slab_prefill()
2702 */
2703 for (;;) {
2704 /*
2705 * If there's a slot available in the current CPU's
2706 * loaded magazine, just put the object there and return.
2707 */
2708 if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2709 ccp->cc_loaded->mag_round[ccp->cc_rounds++] = buf;
2710 ccp->cc_free++;
2711 mutex_exit(&ccp->cc_lock);
2712 return;
2713 }
2714
2715 /*
2716 * The loaded magazine is full. If the previously loaded
2717 * magazine was empty, exchange them and try again.
2718 */
2719 if (ccp->cc_prounds == 0) {
2720 kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2721 continue;
2722 }
2723
2724 /*
2725 * If the magazine layer is disabled, break out now.
2726 */
2727 if (ccp->cc_magsize == 0)
2728 break;
2729
2730 if (!kmem_cpucache_magazine_alloc(ccp, cp)) {
2731 /*
2732 * We couldn't free our constructed object to the
2733 * magazine layer, so apply its destructor and free it
2734 * to the slab layer.
2735 */
2736 break;
2737 }
2738 }
2739 mutex_exit(&ccp->cc_lock);
2740 kmem_slab_free_constructed(cp, buf, B_TRUE);
2741 }
2742
2743 static void
kmem_slab_prefill(kmem_cache_t * cp,kmem_slab_t * sp)2744 kmem_slab_prefill(kmem_cache_t *cp, kmem_slab_t *sp)
2745 {
2746 kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2747 int cache_flags = cp->cache_flags;
2748
2749 kmem_bufctl_t *next, *head;
2750 size_t nbufs;
2751
2752 /*
2753 * Completely allocate the newly created slab and put the pre-allocated
2754 * buffers in magazines. Any of the buffers that cannot be put in
2755 * magazines must be returned to the slab.
2756 */
2757 ASSERT(MUTEX_HELD(&cp->cache_lock));
2758 ASSERT((cache_flags & (KMF_PREFILL|KMF_BUFTAG)) == KMF_PREFILL);
2759 ASSERT(cp->cache_constructor == NULL);
2760 ASSERT(sp->slab_cache == cp);
2761 ASSERT(sp->slab_refcnt == 1);
2762 ASSERT(sp->slab_head != NULL && sp->slab_chunks > sp->slab_refcnt);
2763 ASSERT(avl_find(&cp->cache_partial_slabs, sp, NULL) == NULL);
2764
2765 head = sp->slab_head;
2766 nbufs = (sp->slab_chunks - sp->slab_refcnt);
2767 sp->slab_head = NULL;
2768 sp->slab_refcnt += nbufs;
2769 cp->cache_bufslab -= nbufs;
2770 cp->cache_slab_alloc += nbufs;
2771 list_insert_head(&cp->cache_complete_slabs, sp);
2772 cp->cache_complete_slab_count++;
2773 mutex_exit(&cp->cache_lock);
2774 mutex_enter(&ccp->cc_lock);
2775
2776 while (head != NULL) {
2777 void *buf = KMEM_BUF(cp, head);
2778 /*
2779 * If there's a slot available in the current CPU's
2780 * loaded magazine, just put the object there and
2781 * continue.
2782 */
2783 if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2784 ccp->cc_loaded->mag_round[ccp->cc_rounds++] =
2785 buf;
2786 ccp->cc_free++;
2787 nbufs--;
2788 head = head->bc_next;
2789 continue;
2790 }
2791
2792 /*
2793 * The loaded magazine is full. If the previously
2794 * loaded magazine was empty, exchange them and try
2795 * again.
2796 */
2797 if (ccp->cc_prounds == 0) {
2798 kmem_cpu_reload(ccp, ccp->cc_ploaded,
2799 ccp->cc_prounds);
2800 continue;
2801 }
2802
2803 /*
2804 * If the magazine layer is disabled, break out now.
2805 */
2806
2807 if (ccp->cc_magsize == 0) {
2808 break;
2809 }
2810
2811 if (!kmem_cpucache_magazine_alloc(ccp, cp))
2812 break;
2813 }
2814 mutex_exit(&ccp->cc_lock);
2815 if (nbufs != 0) {
2816 ASSERT(head != NULL);
2817
2818 /*
2819 * If there was a failure, return remaining objects to
2820 * the slab
2821 */
2822 while (head != NULL) {
2823 ASSERT(nbufs != 0);
2824 next = head->bc_next;
2825 head->bc_next = NULL;
2826 kmem_slab_free(cp, KMEM_BUF(cp, head));
2827 head = next;
2828 nbufs--;
2829 }
2830 }
2831 ASSERT(head == NULL);
2832 ASSERT(nbufs == 0);
2833 mutex_enter(&cp->cache_lock);
2834 }
2835
2836 void *
kmem_zalloc(size_t size,int kmflag)2837 kmem_zalloc(size_t size, int kmflag)
2838 {
2839 size_t index;
2840 void *buf;
2841
2842 if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2843 kmem_cache_t *cp = kmem_alloc_table[index];
2844 buf = kmem_cache_alloc(cp, kmflag);
2845 if (buf != NULL) {
2846 if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2847 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2848 ((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2849 ((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2850
2851 if (cp->cache_flags & KMF_LITE) {
2852 KMEM_BUFTAG_LITE_ENTER(btp,
2853 kmem_lite_count, caller());
2854 }
2855 }
2856 bzero(buf, size);
2857 }
2858 } else {
2859 buf = kmem_alloc(size, kmflag);
2860 if (buf != NULL)
2861 bzero(buf, size);
2862 }
2863 return (buf);
2864 }
2865
2866 void *
kmem_alloc(size_t size,int kmflag)2867 kmem_alloc(size_t size, int kmflag)
2868 {
2869 size_t index;
2870 kmem_cache_t *cp;
2871 void *buf;
2872
2873 if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2874 cp = kmem_alloc_table[index];
2875 /* fall through to kmem_cache_alloc() */
2876
2877 } else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2878 kmem_big_alloc_table_max) {
2879 cp = kmem_big_alloc_table[index];
2880 /* fall through to kmem_cache_alloc() */
2881
2882 } else {
2883 if (size == 0)
2884 return (NULL);
2885
2886 buf = vmem_alloc(kmem_oversize_arena, size,
2887 kmflag & KM_VMFLAGS);
2888 if (buf == NULL)
2889 kmem_log_event(kmem_failure_log, NULL, NULL,
2890 (void *)size);
2891 else if (KMEM_DUMP(kmem_slab_cache)) {
2892 /* stats for dump intercept */
2893 kmem_dump_oversize_allocs++;
2894 if (size > kmem_dump_oversize_max)
2895 kmem_dump_oversize_max = size;
2896 }
2897 return (buf);
2898 }
2899
2900 buf = kmem_cache_alloc(cp, kmflag);
2901 if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp) && buf != NULL) {
2902 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2903 ((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2904 ((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2905
2906 if (cp->cache_flags & KMF_LITE) {
2907 KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller());
2908 }
2909 }
2910 return (buf);
2911 }
2912
2913 void
kmem_free(void * buf,size_t size)2914 kmem_free(void *buf, size_t size)
2915 {
2916 size_t index;
2917 kmem_cache_t *cp;
2918
2919 if ((index = (size - 1) >> KMEM_ALIGN_SHIFT) < KMEM_ALLOC_TABLE_MAX) {
2920 cp = kmem_alloc_table[index];
2921 /* fall through to kmem_cache_free() */
2922
2923 } else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2924 kmem_big_alloc_table_max) {
2925 cp = kmem_big_alloc_table[index];
2926 /* fall through to kmem_cache_free() */
2927
2928 } else {
2929 EQUIV(buf == NULL, size == 0);
2930 if (buf == NULL && size == 0)
2931 return;
2932 vmem_free(kmem_oversize_arena, buf, size);
2933 return;
2934 }
2935
2936 if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2937 kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2938 uint32_t *ip = (uint32_t *)btp;
2939 if (ip[1] != KMEM_SIZE_ENCODE(size)) {
2940 if (*(uint64_t *)buf == KMEM_FREE_PATTERN) {
2941 kmem_error(KMERR_DUPFREE, cp, buf);
2942 return;
2943 }
2944 if (KMEM_SIZE_VALID(ip[1])) {
2945 ip[0] = KMEM_SIZE_ENCODE(size);
2946 kmem_error(KMERR_BADSIZE, cp, buf);
2947 } else {
2948 kmem_error(KMERR_REDZONE, cp, buf);
2949 }
2950 return;
2951 }
2952 if (((uint8_t *)buf)[size] != KMEM_REDZONE_BYTE) {
2953 kmem_error(KMERR_REDZONE, cp, buf);
2954 return;
2955 }
2956 btp->bt_redzone = KMEM_REDZONE_PATTERN;
2957 if (cp->cache_flags & KMF_LITE) {
2958 KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count,
2959 caller());
2960 }
2961 }
2962 kmem_cache_free(cp, buf);
2963 }
2964
2965 void *
kmem_firewall_va_alloc(vmem_t * vmp,size_t size,int vmflag)2966 kmem_firewall_va_alloc(vmem_t *vmp, size_t size, int vmflag)
2967 {
2968 size_t realsize = size + vmp->vm_quantum;
2969 void *addr;
2970
2971 /*
2972 * Annoying edge case: if 'size' is just shy of ULONG_MAX, adding
2973 * vm_quantum will cause integer wraparound. Check for this, and
2974 * blow off the firewall page in this case. Note that such a
2975 * giant allocation (the entire kernel address space) can never
2976 * be satisfied, so it will either fail immediately (VM_NOSLEEP)
2977 * or sleep forever (VM_SLEEP). Thus, there is no need for a
2978 * corresponding check in kmem_firewall_va_free().
2979 */
2980 if (realsize < size)
2981 realsize = size;
2982
2983 /*
2984 * While boot still owns resource management, make sure that this
2985 * redzone virtual address allocation is properly accounted for in
2986 * OBPs "virtual-memory" "available" lists because we're
2987 * effectively claiming them for a red zone. If we don't do this,
2988 * the available lists become too fragmented and too large for the
2989 * current boot/kernel memory list interface.
2990 */
2991 addr = vmem_alloc(vmp, realsize, vmflag | VM_NEXTFIT);
2992
2993 if (addr != NULL && kvseg.s_base == NULL && realsize != size)
2994 (void) boot_virt_alloc((char *)addr + size, vmp->vm_quantum);
2995
2996 return (addr);
2997 }
2998
2999 void
kmem_firewall_va_free(vmem_t * vmp,void * addr,size_t size)3000 kmem_firewall_va_free(vmem_t *vmp, void *addr, size_t size)
3001 {
3002 ASSERT((kvseg.s_base == NULL ?
3003 va_to_pfn((char *)addr + size) :
3004 hat_getpfnum(kas.a_hat, (caddr_t)addr + size)) == PFN_INVALID);
3005
3006 vmem_free(vmp, addr, size + vmp->vm_quantum);
3007 }
3008
3009 /*
3010 * Try to allocate at least `size' bytes of memory without sleeping or
3011 * panicking. Return actual allocated size in `asize'. If allocation failed,
3012 * try final allocation with sleep or panic allowed.
3013 */
3014 void *
kmem_alloc_tryhard(size_t size,size_t * asize,int kmflag)3015 kmem_alloc_tryhard(size_t size, size_t *asize, int kmflag)
3016 {
3017 void *p;
3018
3019 *asize = P2ROUNDUP(size, KMEM_ALIGN);
3020 do {
3021 p = kmem_alloc(*asize, (kmflag | KM_NOSLEEP) & ~KM_PANIC);
3022 if (p != NULL)
3023 return (p);
3024 *asize += KMEM_ALIGN;
3025 } while (*asize <= PAGESIZE);
3026
3027 *asize = P2ROUNDUP(size, KMEM_ALIGN);
3028 return (kmem_alloc(*asize, kmflag));
3029 }
3030
3031 /*
3032 * Reclaim all unused memory from a cache.
3033 */
3034 static void
kmem_cache_reap(kmem_cache_t * cp)3035 kmem_cache_reap(kmem_cache_t *cp)
3036 {
3037 ASSERT(taskq_member(kmem_taskq, curthread));
3038 cp->cache_reap++;
3039
3040 /*
3041 * Ask the cache's owner to free some memory if possible.
3042 * The idea is to handle things like the inode cache, which
3043 * typically sits on a bunch of memory that it doesn't truly
3044 * *need*. Reclaim policy is entirely up to the owner; this
3045 * callback is just an advisory plea for help.
3046 */
3047 if (cp->cache_reclaim != NULL) {
3048 long delta;
3049
3050 /*
3051 * Reclaimed memory should be reapable (not included in the
3052 * depot's working set).
3053 */
3054 delta = cp->cache_full.ml_total;
3055 cp->cache_reclaim(cp->cache_private);
3056 delta = cp->cache_full.ml_total - delta;
3057 if (delta > 0) {
3058 mutex_enter(&cp->cache_depot_lock);
3059 cp->cache_full.ml_reaplimit += delta;
3060 cp->cache_full.ml_min += delta;
3061 mutex_exit(&cp->cache_depot_lock);
3062 }
3063 }
3064
3065 kmem_depot_ws_reap(cp);
3066
3067 if (cp->cache_defrag != NULL && !kmem_move_noreap) {
3068 kmem_cache_defrag(cp);
3069 }
3070 }
3071
3072 static void
kmem_reap_timeout(void * flag_arg)3073 kmem_reap_timeout(void *flag_arg)
3074 {
3075 uint32_t *flag = (uint32_t *)flag_arg;
3076
3077 ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3078 *flag = 0;
3079 }
3080
3081 static void
kmem_reap_done(void * flag)3082 kmem_reap_done(void *flag)
3083 {
3084 if (!callout_init_done) {
3085 /* can't schedule a timeout at this point */
3086 kmem_reap_timeout(flag);
3087 } else {
3088 (void) timeout(kmem_reap_timeout, flag, kmem_reap_interval);
3089 }
3090 }
3091
3092 static void
kmem_reap_start(void * flag)3093 kmem_reap_start(void *flag)
3094 {
3095 ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3096
3097 if (flag == &kmem_reaping) {
3098 kmem_cache_applyall(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3099 /*
3100 * if we have segkp under heap, reap segkp cache.
3101 */
3102 if (segkp_fromheap)
3103 segkp_cache_free();
3104 }
3105 else
3106 kmem_cache_applyall_id(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3107
3108 /*
3109 * We use taskq_dispatch() to schedule a timeout to clear
3110 * the flag so that kmem_reap() becomes self-throttling:
3111 * we won't reap again until the current reap completes *and*
3112 * at least kmem_reap_interval ticks have elapsed.
3113 */
3114 if (!taskq_dispatch(kmem_taskq, kmem_reap_done, flag, TQ_NOSLEEP))
3115 kmem_reap_done(flag);
3116 }
3117
3118 static void
kmem_reap_common(void * flag_arg)3119 kmem_reap_common(void *flag_arg)
3120 {
3121 uint32_t *flag = (uint32_t *)flag_arg;
3122
3123 if (MUTEX_HELD(&kmem_cache_lock) || kmem_taskq == NULL ||
3124 atomic_cas_32(flag, 0, 1) != 0)
3125 return;
3126
3127 /*
3128 * It may not be kosher to do memory allocation when a reap is called
3129 * (for example, if vmem_populate() is in the call chain). So we
3130 * start the reap going with a TQ_NOALLOC dispatch. If the dispatch
3131 * fails, we reset the flag, and the next reap will try again.
3132 */
3133 if (!taskq_dispatch(kmem_taskq, kmem_reap_start, flag, TQ_NOALLOC))
3134 *flag = 0;
3135 }
3136
3137 /*
3138 * Reclaim all unused memory from all caches. Called from the VM system
3139 * when memory gets tight.
3140 */
3141 void
kmem_reap(void)3142 kmem_reap(void)
3143 {
3144 kmem_reap_common(&kmem_reaping);
3145 }
3146
3147 /*
3148 * Reclaim all unused memory from identifier arenas, called when a vmem
3149 * arena not back by memory is exhausted. Since reaping memory-backed caches
3150 * cannot help with identifier exhaustion, we avoid both a large amount of
3151 * work and unwanted side-effects from reclaim callbacks.
3152 */
3153 void
kmem_reap_idspace(void)3154 kmem_reap_idspace(void)
3155 {
3156 kmem_reap_common(&kmem_reaping_idspace);
3157 }
3158
3159 /*
3160 * Purge all magazines from a cache and set its magazine limit to zero.
3161 * All calls are serialized by the kmem_taskq lock, except for the final
3162 * call from kmem_cache_destroy().
3163 */
3164 static void
kmem_cache_magazine_purge(kmem_cache_t * cp)3165 kmem_cache_magazine_purge(kmem_cache_t *cp)
3166 {
3167 kmem_cpu_cache_t *ccp;
3168 kmem_magazine_t *mp, *pmp;
3169 int rounds, prounds, cpu_seqid;
3170
3171 ASSERT(!list_link_active(&cp->cache_link) ||
3172 taskq_member(kmem_taskq, curthread));
3173 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
3174
3175 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3176 ccp = &cp->cache_cpu[cpu_seqid];
3177
3178 mutex_enter(&ccp->cc_lock);
3179 mp = ccp->cc_loaded;
3180 pmp = ccp->cc_ploaded;
3181 rounds = ccp->cc_rounds;
3182 prounds = ccp->cc_prounds;
3183 ccp->cc_loaded = NULL;
3184 ccp->cc_ploaded = NULL;
3185 ccp->cc_rounds = -1;
3186 ccp->cc_prounds = -1;
3187 ccp->cc_magsize = 0;
3188 mutex_exit(&ccp->cc_lock);
3189
3190 if (mp)
3191 kmem_magazine_destroy(cp, mp, rounds);
3192 if (pmp)
3193 kmem_magazine_destroy(cp, pmp, prounds);
3194 }
3195
3196 kmem_depot_ws_zero(cp);
3197 kmem_depot_ws_reap(cp);
3198 }
3199
3200 /*
3201 * Enable per-cpu magazines on a cache.
3202 */
3203 static void
kmem_cache_magazine_enable(kmem_cache_t * cp)3204 kmem_cache_magazine_enable(kmem_cache_t *cp)
3205 {
3206 int cpu_seqid;
3207
3208 if (cp->cache_flags & KMF_NOMAGAZINE)
3209 return;
3210
3211 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3212 kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3213 mutex_enter(&ccp->cc_lock);
3214 ccp->cc_magsize = cp->cache_magtype->mt_magsize;
3215 mutex_exit(&ccp->cc_lock);
3216 }
3217
3218 }
3219
3220 /*
3221 * Reap (almost) everything right now.
3222 */
3223 void
kmem_cache_reap_now(kmem_cache_t * cp)3224 kmem_cache_reap_now(kmem_cache_t *cp)
3225 {
3226 ASSERT(list_link_active(&cp->cache_link));
3227
3228 kmem_depot_ws_zero(cp);
3229
3230 (void) taskq_dispatch(kmem_taskq,
3231 (task_func_t *)kmem_depot_ws_reap, cp, TQ_SLEEP);
3232 taskq_wait(kmem_taskq);
3233 }
3234
3235 /*
3236 * Recompute a cache's magazine size. The trade-off is that larger magazines
3237 * provide a higher transfer rate with the depot, while smaller magazines
3238 * reduce memory consumption. Magazine resizing is an expensive operation;
3239 * it should not be done frequently.
3240 *
3241 * Changes to the magazine size are serialized by the kmem_taskq lock.
3242 *
3243 * Note: at present this only grows the magazine size. It might be useful
3244 * to allow shrinkage too.
3245 */
3246 static void
kmem_cache_magazine_resize(kmem_cache_t * cp)3247 kmem_cache_magazine_resize(kmem_cache_t *cp)
3248 {
3249 kmem_magtype_t *mtp = cp->cache_magtype;
3250
3251 ASSERT(taskq_member(kmem_taskq, curthread));
3252
3253 if (cp->cache_chunksize < mtp->mt_maxbuf) {
3254 kmem_cache_magazine_purge(cp);
3255 mutex_enter(&cp->cache_depot_lock);
3256 cp->cache_magtype = ++mtp;
3257 cp->cache_depot_contention_prev =
3258 cp->cache_depot_contention + INT_MAX;
3259 mutex_exit(&cp->cache_depot_lock);
3260 kmem_cache_magazine_enable(cp);
3261 }
3262 }
3263
3264 /*
3265 * Rescale a cache's hash table, so that the table size is roughly the
3266 * cache size. We want the average lookup time to be extremely small.
3267 */
3268 static void
kmem_hash_rescale(kmem_cache_t * cp)3269 kmem_hash_rescale(kmem_cache_t *cp)
3270 {
3271 kmem_bufctl_t **old_table, **new_table, *bcp;
3272 size_t old_size, new_size, h;
3273
3274 ASSERT(taskq_member(kmem_taskq, curthread));
3275
3276 new_size = MAX(KMEM_HASH_INITIAL,
3277 1 << (highbit(3 * cp->cache_buftotal + 4) - 2));
3278 old_size = cp->cache_hash_mask + 1;
3279
3280 if ((old_size >> 1) <= new_size && new_size <= (old_size << 1))
3281 return;
3282
3283 new_table = vmem_alloc(kmem_hash_arena, new_size * sizeof (void *),
3284 VM_NOSLEEP);
3285 if (new_table == NULL)
3286 return;
3287 bzero(new_table, new_size * sizeof (void *));
3288
3289 mutex_enter(&cp->cache_lock);
3290
3291 old_size = cp->cache_hash_mask + 1;
3292 old_table = cp->cache_hash_table;
3293
3294 cp->cache_hash_mask = new_size - 1;
3295 cp->cache_hash_table = new_table;
3296 cp->cache_rescale++;
3297
3298 for (h = 0; h < old_size; h++) {
3299 bcp = old_table[h];
3300 while (bcp != NULL) {
3301 void *addr = bcp->bc_addr;
3302 kmem_bufctl_t *next_bcp = bcp->bc_next;
3303 kmem_bufctl_t **hash_bucket = KMEM_HASH(cp, addr);
3304 bcp->bc_next = *hash_bucket;
3305 *hash_bucket = bcp;
3306 bcp = next_bcp;
3307 }
3308 }
3309
3310 mutex_exit(&cp->cache_lock);
3311
3312 vmem_free(kmem_hash_arena, old_table, old_size * sizeof (void *));
3313 }
3314
3315 /*
3316 * Perform periodic maintenance on a cache: hash rescaling, depot working-set
3317 * update, magazine resizing, and slab consolidation.
3318 */
3319 static void
kmem_cache_update(kmem_cache_t * cp)3320 kmem_cache_update(kmem_cache_t *cp)
3321 {
3322 int need_hash_rescale = 0;
3323 int need_magazine_resize = 0;
3324
3325 ASSERT(MUTEX_HELD(&kmem_cache_lock));
3326
3327 /*
3328 * If the cache has become much larger or smaller than its hash table,
3329 * fire off a request to rescale the hash table.
3330 */
3331 mutex_enter(&cp->cache_lock);
3332
3333 if ((cp->cache_flags & KMF_HASH) &&
3334 (cp->cache_buftotal > (cp->cache_hash_mask << 1) ||
3335 (cp->cache_buftotal < (cp->cache_hash_mask >> 1) &&
3336 cp->cache_hash_mask > KMEM_HASH_INITIAL)))
3337 need_hash_rescale = 1;
3338
3339 mutex_exit(&cp->cache_lock);
3340
3341 /*
3342 * Update the depot working set statistics.
3343 */
3344 kmem_depot_ws_update(cp);
3345
3346 /*
3347 * If there's a lot of contention in the depot,
3348 * increase the magazine size.
3349 */
3350 mutex_enter(&cp->cache_depot_lock);
3351
3352 if (cp->cache_chunksize < cp->cache_magtype->mt_maxbuf &&
3353 (int)(cp->cache_depot_contention -
3354 cp->cache_depot_contention_prev) > kmem_depot_contention)
3355 need_magazine_resize = 1;
3356
3357 cp->cache_depot_contention_prev = cp->cache_depot_contention;
3358
3359 mutex_exit(&cp->cache_depot_lock);
3360
3361 if (need_hash_rescale)
3362 (void) taskq_dispatch(kmem_taskq,
3363 (task_func_t *)kmem_hash_rescale, cp, TQ_NOSLEEP);
3364
3365 if (need_magazine_resize)
3366 (void) taskq_dispatch(kmem_taskq,
3367 (task_func_t *)kmem_cache_magazine_resize, cp, TQ_NOSLEEP);
3368
3369 if (cp->cache_defrag != NULL)
3370 (void) taskq_dispatch(kmem_taskq,
3371 (task_func_t *)kmem_cache_scan, cp, TQ_NOSLEEP);
3372 }
3373
3374 static void kmem_update(void *);
3375
3376 static void
kmem_update_timeout(void * dummy)3377 kmem_update_timeout(void *dummy)
3378 {
3379 (void) timeout(kmem_update, dummy, kmem_reap_interval);
3380 }
3381
3382 static void
kmem_update(void * dummy)3383 kmem_update(void *dummy)
3384 {
3385 kmem_cache_applyall(kmem_cache_update, NULL, TQ_NOSLEEP);
3386
3387 /*
3388 * We use taskq_dispatch() to reschedule the timeout so that
3389 * kmem_update() becomes self-throttling: it won't schedule
3390 * new tasks until all previous tasks have completed.
3391 */
3392 if (!taskq_dispatch(kmem_taskq, kmem_update_timeout, dummy, TQ_NOSLEEP))
3393 kmem_update_timeout(NULL);
3394 }
3395
3396 static int
kmem_cache_kstat_update(kstat_t * ksp,int rw)3397 kmem_cache_kstat_update(kstat_t *ksp, int rw)
3398 {
3399 struct kmem_cache_kstat *kmcp = &kmem_cache_kstat;
3400 kmem_cache_t *cp = ksp->ks_private;
3401 uint64_t cpu_buf_avail;
3402 uint64_t buf_avail = 0;
3403 int cpu_seqid;
3404 long reap;
3405
3406 ASSERT(MUTEX_HELD(&kmem_cache_kstat_lock));
3407
3408 if (rw == KSTAT_WRITE)
3409 return (EACCES);
3410
3411 mutex_enter(&cp->cache_lock);
3412
3413 kmcp->kmc_alloc_fail.value.ui64 = cp->cache_alloc_fail;
3414 kmcp->kmc_alloc.value.ui64 = cp->cache_slab_alloc;
3415 kmcp->kmc_free.value.ui64 = cp->cache_slab_free;
3416 kmcp->kmc_slab_alloc.value.ui64 = cp->cache_slab_alloc;
3417 kmcp->kmc_slab_free.value.ui64 = cp->cache_slab_free;
3418
3419 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3420 kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3421
3422 mutex_enter(&ccp->cc_lock);
3423
3424 cpu_buf_avail = 0;
3425 if (ccp->cc_rounds > 0)
3426 cpu_buf_avail += ccp->cc_rounds;
3427 if (ccp->cc_prounds > 0)
3428 cpu_buf_avail += ccp->cc_prounds;
3429
3430 kmcp->kmc_alloc.value.ui64 += ccp->cc_alloc;
3431 kmcp->kmc_free.value.ui64 += ccp->cc_free;
3432 buf_avail += cpu_buf_avail;
3433
3434 mutex_exit(&ccp->cc_lock);
3435 }
3436
3437 mutex_enter(&cp->cache_depot_lock);
3438
3439 kmcp->kmc_depot_alloc.value.ui64 = cp->cache_full.ml_alloc;
3440 kmcp->kmc_depot_free.value.ui64 = cp->cache_empty.ml_alloc;
3441 kmcp->kmc_depot_contention.value.ui64 = cp->cache_depot_contention;
3442 kmcp->kmc_full_magazines.value.ui64 = cp->cache_full.ml_total;
3443 kmcp->kmc_empty_magazines.value.ui64 = cp->cache_empty.ml_total;
3444 kmcp->kmc_magazine_size.value.ui64 =
3445 (cp->cache_flags & KMF_NOMAGAZINE) ?
3446 0 : cp->cache_magtype->mt_magsize;
3447
3448 kmcp->kmc_alloc.value.ui64 += cp->cache_full.ml_alloc;
3449 kmcp->kmc_free.value.ui64 += cp->cache_empty.ml_alloc;
3450 buf_avail += cp->cache_full.ml_total * cp->cache_magtype->mt_magsize;
3451
3452 reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
3453 reap = MIN(reap, cp->cache_full.ml_total);
3454
3455 mutex_exit(&cp->cache_depot_lock);
3456
3457 kmcp->kmc_buf_size.value.ui64 = cp->cache_bufsize;
3458 kmcp->kmc_align.value.ui64 = cp->cache_align;
3459 kmcp->kmc_chunk_size.value.ui64 = cp->cache_chunksize;
3460 kmcp->kmc_slab_size.value.ui64 = cp->cache_slabsize;
3461 kmcp->kmc_buf_constructed.value.ui64 = buf_avail;
3462 buf_avail += cp->cache_bufslab;
3463 kmcp->kmc_buf_avail.value.ui64 = buf_avail;
3464 kmcp->kmc_buf_inuse.value.ui64 = cp->cache_buftotal - buf_avail;
3465 kmcp->kmc_buf_total.value.ui64 = cp->cache_buftotal;
3466 kmcp->kmc_buf_max.value.ui64 = cp->cache_bufmax;
3467 kmcp->kmc_slab_create.value.ui64 = cp->cache_slab_create;
3468 kmcp->kmc_slab_destroy.value.ui64 = cp->cache_slab_destroy;
3469 kmcp->kmc_hash_size.value.ui64 = (cp->cache_flags & KMF_HASH) ?
3470 cp->cache_hash_mask + 1 : 0;
3471 kmcp->kmc_hash_lookup_depth.value.ui64 = cp->cache_lookup_depth;
3472 kmcp->kmc_hash_rescale.value.ui64 = cp->cache_rescale;
3473 kmcp->kmc_vmem_source.value.ui64 = cp->cache_arena->vm_id;
3474 kmcp->kmc_reap.value.ui64 = cp->cache_reap;
3475
3476 if (cp->cache_defrag == NULL) {
3477 kmcp->kmc_move_callbacks.value.ui64 = 0;
3478 kmcp->kmc_move_yes.value.ui64 = 0;
3479 kmcp->kmc_move_no.value.ui64 = 0;
3480 kmcp->kmc_move_later.value.ui64 = 0;
3481 kmcp->kmc_move_dont_need.value.ui64 = 0;
3482 kmcp->kmc_move_dont_know.value.ui64 = 0;
3483 kmcp->kmc_move_hunt_found.value.ui64 = 0;
3484 kmcp->kmc_move_slabs_freed.value.ui64 = 0;
3485 kmcp->kmc_defrag.value.ui64 = 0;
3486 kmcp->kmc_scan.value.ui64 = 0;
3487 kmcp->kmc_move_reclaimable.value.ui64 = 0;
3488 } else {
3489 int64_t reclaimable;
3490
3491 kmem_defrag_t *kd = cp->cache_defrag;
3492 kmcp->kmc_move_callbacks.value.ui64 = kd->kmd_callbacks;
3493 kmcp->kmc_move_yes.value.ui64 = kd->kmd_yes;
3494 kmcp->kmc_move_no.value.ui64 = kd->kmd_no;
3495 kmcp->kmc_move_later.value.ui64 = kd->kmd_later;
3496 kmcp->kmc_move_dont_need.value.ui64 = kd->kmd_dont_need;
3497 kmcp->kmc_move_dont_know.value.ui64 = kd->kmd_dont_know;
3498 kmcp->kmc_move_hunt_found.value.ui64 = kd->kmd_hunt_found;
3499 kmcp->kmc_move_slabs_freed.value.ui64 = kd->kmd_slabs_freed;
3500 kmcp->kmc_defrag.value.ui64 = kd->kmd_defrags;
3501 kmcp->kmc_scan.value.ui64 = kd->kmd_scans;
3502
3503 reclaimable = cp->cache_bufslab - (cp->cache_maxchunks - 1);
3504 reclaimable = MAX(reclaimable, 0);
3505 reclaimable += ((uint64_t)reap * cp->cache_magtype->mt_magsize);
3506 kmcp->kmc_move_reclaimable.value.ui64 = reclaimable;
3507 }
3508
3509 mutex_exit(&cp->cache_lock);
3510 return (0);
3511 }
3512
3513 /*
3514 * Return a named statistic about a particular cache.
3515 * This shouldn't be called very often, so it's currently designed for
3516 * simplicity (leverages existing kstat support) rather than efficiency.
3517 */
3518 uint64_t
kmem_cache_stat(kmem_cache_t * cp,char * name)3519 kmem_cache_stat(kmem_cache_t *cp, char *name)
3520 {
3521 int i;
3522 kstat_t *ksp = cp->cache_kstat;
3523 kstat_named_t *knp = (kstat_named_t *)&kmem_cache_kstat;
3524 uint64_t value = 0;
3525
3526 if (ksp != NULL) {
3527 mutex_enter(&kmem_cache_kstat_lock);
3528 (void) kmem_cache_kstat_update(ksp, KSTAT_READ);
3529 for (i = 0; i < ksp->ks_ndata; i++) {
3530 if (strcmp(knp[i].name, name) == 0) {
3531 value = knp[i].value.ui64;
3532 break;
3533 }
3534 }
3535 mutex_exit(&kmem_cache_kstat_lock);
3536 }
3537 return (value);
3538 }
3539
3540 /*
3541 * Return an estimate of currently available kernel heap memory.
3542 * On 32-bit systems, physical memory may exceed virtual memory,
3543 * we just truncate the result at 1GB.
3544 */
3545 size_t
kmem_avail(void)3546 kmem_avail(void)
3547 {
3548 spgcnt_t rmem = availrmem - tune.t_minarmem;
3549 spgcnt_t fmem = freemem - minfree;
3550
3551 return ((size_t)ptob(MIN(MAX(MIN(rmem, fmem), 0),
3552 1 << (30 - PAGESHIFT))));
3553 }
3554
3555 /*
3556 * Return the maximum amount of memory that is (in theory) allocatable
3557 * from the heap. This may be used as an estimate only since there
3558 * is no guarentee this space will still be available when an allocation
3559 * request is made, nor that the space may be allocated in one big request
3560 * due to kernel heap fragmentation.
3561 */
3562 size_t
kmem_maxavail(void)3563 kmem_maxavail(void)
3564 {
3565 spgcnt_t pmem = availrmem - tune.t_minarmem;
3566 spgcnt_t vmem = btop(vmem_size(heap_arena, VMEM_FREE));
3567
3568 return ((size_t)ptob(MAX(MIN(pmem, vmem), 0)));
3569 }
3570
3571 /*
3572 * Indicate whether memory-intensive kmem debugging is enabled.
3573 */
3574 int
kmem_debugging(void)3575 kmem_debugging(void)
3576 {
3577 return (kmem_flags & (KMF_AUDIT | KMF_REDZONE));
3578 }
3579
3580 /* binning function, sorts finely at the two extremes */
3581 #define KMEM_PARTIAL_SLAB_WEIGHT(sp, binshift) \
3582 ((((sp)->slab_refcnt <= (binshift)) || \
3583 (((sp)->slab_chunks - (sp)->slab_refcnt) <= (binshift))) \
3584 ? -(sp)->slab_refcnt \
3585 : -((binshift) + ((sp)->slab_refcnt >> (binshift))))
3586
3587 /*
3588 * Minimizing the number of partial slabs on the freelist minimizes
3589 * fragmentation (the ratio of unused buffers held by the slab layer). There are
3590 * two ways to get a slab off of the freelist: 1) free all the buffers on the
3591 * slab, and 2) allocate all the buffers on the slab. It follows that we want
3592 * the most-used slabs at the front of the list where they have the best chance
3593 * of being completely allocated, and the least-used slabs at a safe distance
3594 * from the front to improve the odds that the few remaining buffers will all be
3595 * freed before another allocation can tie up the slab. For that reason a slab
3596 * with a higher slab_refcnt sorts less than than a slab with a lower
3597 * slab_refcnt.
3598 *
3599 * However, if a slab has at least one buffer that is deemed unfreeable, we
3600 * would rather have that slab at the front of the list regardless of
3601 * slab_refcnt, since even one unfreeable buffer makes the entire slab
3602 * unfreeable. If the client returns KMEM_CBRC_NO in response to a cache_move()
3603 * callback, the slab is marked unfreeable for as long as it remains on the
3604 * freelist.
3605 */
3606 static int
kmem_partial_slab_cmp(const void * p0,const void * p1)3607 kmem_partial_slab_cmp(const void *p0, const void *p1)
3608 {
3609 const kmem_cache_t *cp;
3610 const kmem_slab_t *s0 = p0;
3611 const kmem_slab_t *s1 = p1;
3612 int w0, w1;
3613 size_t binshift;
3614
3615 ASSERT(KMEM_SLAB_IS_PARTIAL(s0));
3616 ASSERT(KMEM_SLAB_IS_PARTIAL(s1));
3617 ASSERT(s0->slab_cache == s1->slab_cache);
3618 cp = s1->slab_cache;
3619 ASSERT(MUTEX_HELD(&cp->cache_lock));
3620 binshift = cp->cache_partial_binshift;
3621
3622 /* weight of first slab */
3623 w0 = KMEM_PARTIAL_SLAB_WEIGHT(s0, binshift);
3624 if (s0->slab_flags & KMEM_SLAB_NOMOVE) {
3625 w0 -= cp->cache_maxchunks;
3626 }
3627
3628 /* weight of second slab */
3629 w1 = KMEM_PARTIAL_SLAB_WEIGHT(s1, binshift);
3630 if (s1->slab_flags & KMEM_SLAB_NOMOVE) {
3631 w1 -= cp->cache_maxchunks;
3632 }
3633
3634 if (w0 < w1)
3635 return (-1);
3636 if (w0 > w1)
3637 return (1);
3638
3639 /* compare pointer values */
3640 if ((uintptr_t)s0 < (uintptr_t)s1)
3641 return (-1);
3642 if ((uintptr_t)s0 > (uintptr_t)s1)
3643 return (1);
3644
3645 return (0);
3646 }
3647
3648 /*
3649 * It must be valid to call the destructor (if any) on a newly created object.
3650 * That is, the constructor (if any) must leave the object in a valid state for
3651 * the destructor.
3652 */
3653 kmem_cache_t *
kmem_cache_create(char * name,size_t bufsize,size_t align,int (* constructor)(void *,void *,int),void (* destructor)(void *,void *),void (* reclaim)(void *),void * private,vmem_t * vmp,int cflags)3654 kmem_cache_create(
3655 char *name, /* descriptive name for this cache */
3656 size_t bufsize, /* size of the objects it manages */
3657 size_t align, /* required object alignment */
3658 int (*constructor)(void *, void *, int), /* object constructor */
3659 void (*destructor)(void *, void *), /* object destructor */
3660 void (*reclaim)(void *), /* memory reclaim callback */
3661 void *private, /* pass-thru arg for constr/destr/reclaim */
3662 vmem_t *vmp, /* vmem source for slab allocation */
3663 int cflags) /* cache creation flags */
3664 {
3665 int cpu_seqid;
3666 size_t chunksize;
3667 kmem_cache_t *cp;
3668 kmem_magtype_t *mtp;
3669 size_t csize = KMEM_CACHE_SIZE(max_ncpus);
3670
3671 #ifdef DEBUG
3672 /*
3673 * Cache names should conform to the rules for valid C identifiers
3674 */
3675 if (!strident_valid(name)) {
3676 cmn_err(CE_CONT,
3677 "kmem_cache_create: '%s' is an invalid cache name\n"
3678 "cache names must conform to the rules for "
3679 "C identifiers\n", name);
3680 }
3681 #endif /* DEBUG */
3682
3683 if (vmp == NULL)
3684 vmp = kmem_default_arena;
3685
3686 /*
3687 * If this kmem cache has an identifier vmem arena as its source, mark
3688 * it such to allow kmem_reap_idspace().
3689 */
3690 ASSERT(!(cflags & KMC_IDENTIFIER)); /* consumer should not set this */
3691 if (vmp->vm_cflags & VMC_IDENTIFIER)
3692 cflags |= KMC_IDENTIFIER;
3693
3694 /*
3695 * Get a kmem_cache structure. We arrange that cp->cache_cpu[]
3696 * is aligned on a KMEM_CPU_CACHE_SIZE boundary to prevent
3697 * false sharing of per-CPU data.
3698 */
3699 cp = vmem_xalloc(kmem_cache_arena, csize, KMEM_CPU_CACHE_SIZE,
3700 P2NPHASE(csize, KMEM_CPU_CACHE_SIZE), 0, NULL, NULL, VM_SLEEP);
3701 bzero(cp, csize);
3702 list_link_init(&cp->cache_link);
3703
3704 if (align == 0)
3705 align = KMEM_ALIGN;
3706
3707 /*
3708 * If we're not at least KMEM_ALIGN aligned, we can't use free
3709 * memory to hold bufctl information (because we can't safely
3710 * perform word loads and stores on it).
3711 */
3712 if (align < KMEM_ALIGN)
3713 cflags |= KMC_NOTOUCH;
3714
3715 if (!ISP2(align) || align > vmp->vm_quantum)
3716 panic("kmem_cache_create: bad alignment %lu", align);
3717
3718 mutex_enter(&kmem_flags_lock);
3719 if (kmem_flags & KMF_RANDOMIZE)
3720 kmem_flags = (((kmem_flags | ~KMF_RANDOM) + 1) & KMF_RANDOM) |
3721 KMF_RANDOMIZE;
3722 cp->cache_flags = (kmem_flags | cflags) & KMF_DEBUG;
3723 mutex_exit(&kmem_flags_lock);
3724
3725 /*
3726 * Make sure all the various flags are reasonable.
3727 */
3728 ASSERT(!(cflags & KMC_NOHASH) || !(cflags & KMC_NOTOUCH));
3729
3730 if (cp->cache_flags & KMF_LITE) {
3731 if (bufsize >= kmem_lite_minsize &&
3732 align <= kmem_lite_maxalign &&
3733 P2PHASE(bufsize, kmem_lite_maxalign) != 0) {
3734 cp->cache_flags |= KMF_BUFTAG;
3735 cp->cache_flags &= ~(KMF_AUDIT | KMF_FIREWALL);
3736 } else {
3737 cp->cache_flags &= ~KMF_DEBUG;
3738 }
3739 }
3740
3741 if (cp->cache_flags & KMF_DEADBEEF)
3742 cp->cache_flags |= KMF_REDZONE;
3743
3744 if ((cflags & KMC_QCACHE) && (cp->cache_flags & KMF_AUDIT))
3745 cp->cache_flags |= KMF_NOMAGAZINE;
3746
3747 if (cflags & KMC_NODEBUG)
3748 cp->cache_flags &= ~KMF_DEBUG;
3749
3750 if (cflags & KMC_NOTOUCH)
3751 cp->cache_flags &= ~KMF_TOUCH;
3752
3753 if (cflags & KMC_PREFILL)
3754 cp->cache_flags |= KMF_PREFILL;
3755
3756 if (cflags & KMC_NOHASH)
3757 cp->cache_flags &= ~(KMF_AUDIT | KMF_FIREWALL);
3758
3759 if (cflags & KMC_NOMAGAZINE)
3760 cp->cache_flags |= KMF_NOMAGAZINE;
3761
3762 if ((cp->cache_flags & KMF_AUDIT) && !(cflags & KMC_NOTOUCH))
3763 cp->cache_flags |= KMF_REDZONE;
3764
3765 if (!(cp->cache_flags & KMF_AUDIT))
3766 cp->cache_flags &= ~KMF_CONTENTS;
3767
3768 if ((cp->cache_flags & KMF_BUFTAG) && bufsize >= kmem_minfirewall &&
3769 !(cp->cache_flags & KMF_LITE) && !(cflags & KMC_NOHASH))
3770 cp->cache_flags |= KMF_FIREWALL;
3771
3772 if (vmp != kmem_default_arena || kmem_firewall_arena == NULL)
3773 cp->cache_flags &= ~KMF_FIREWALL;
3774
3775 if (cp->cache_flags & KMF_FIREWALL) {
3776 cp->cache_flags &= ~KMF_BUFTAG;
3777 cp->cache_flags |= KMF_NOMAGAZINE;
3778 ASSERT(vmp == kmem_default_arena);
3779 vmp = kmem_firewall_arena;
3780 }
3781
3782 /*
3783 * Set cache properties.
3784 */
3785 (void) strncpy(cp->cache_name, name, KMEM_CACHE_NAMELEN);
3786 strident_canon(cp->cache_name, KMEM_CACHE_NAMELEN + 1);
3787 cp->cache_bufsize = bufsize;
3788 cp->cache_align = align;
3789 cp->cache_constructor = constructor;
3790 cp->cache_destructor = destructor;
3791 cp->cache_reclaim = reclaim;
3792 cp->cache_private = private;
3793 cp->cache_arena = vmp;
3794 cp->cache_cflags = cflags;
3795
3796 /*
3797 * Determine the chunk size.
3798 */
3799 chunksize = bufsize;
3800
3801 if (align >= KMEM_ALIGN) {
3802 chunksize = P2ROUNDUP(chunksize, KMEM_ALIGN);
3803 cp->cache_bufctl = chunksize - KMEM_ALIGN;
3804 }
3805
3806 if (cp->cache_flags & KMF_BUFTAG) {
3807 cp->cache_bufctl = chunksize;
3808 cp->cache_buftag = chunksize;
3809 if (cp->cache_flags & KMF_LITE)
3810 chunksize += KMEM_BUFTAG_LITE_SIZE(kmem_lite_count);
3811 else
3812 chunksize += sizeof (kmem_buftag_t);
3813 }
3814
3815 if (cp->cache_flags & KMF_DEADBEEF) {
3816 cp->cache_verify = MIN(cp->cache_buftag, kmem_maxverify);
3817 if (cp->cache_flags & KMF_LITE)
3818 cp->cache_verify = sizeof (uint64_t);
3819 }
3820
3821 cp->cache_contents = MIN(cp->cache_bufctl, kmem_content_maxsave);
3822
3823 cp->cache_chunksize = chunksize = P2ROUNDUP(chunksize, align);
3824
3825 /*
3826 * Now that we know the chunk size, determine the optimal slab size.
3827 */
3828 if (vmp == kmem_firewall_arena) {
3829 cp->cache_slabsize = P2ROUNDUP(chunksize, vmp->vm_quantum);
3830 cp->cache_mincolor = cp->cache_slabsize - chunksize;
3831 cp->cache_maxcolor = cp->cache_mincolor;
3832 cp->cache_flags |= KMF_HASH;
3833 ASSERT(!(cp->cache_flags & KMF_BUFTAG));
3834 } else if ((cflags & KMC_NOHASH) || (!(cflags & KMC_NOTOUCH) &&
3835 !(cp->cache_flags & KMF_AUDIT) &&
3836 chunksize < vmp->vm_quantum / KMEM_VOID_FRACTION)) {
3837 cp->cache_slabsize = vmp->vm_quantum;
3838 cp->cache_mincolor = 0;
3839 cp->cache_maxcolor =
3840 (cp->cache_slabsize - sizeof (kmem_slab_t)) % chunksize;
3841 ASSERT(chunksize + sizeof (kmem_slab_t) <= cp->cache_slabsize);
3842 ASSERT(!(cp->cache_flags & KMF_AUDIT));
3843 } else {
3844 size_t chunks, bestfit, waste, slabsize;
3845 size_t minwaste = LONG_MAX;
3846
3847 for (chunks = 1; chunks <= KMEM_VOID_FRACTION; chunks++) {
3848 slabsize = P2ROUNDUP(chunksize * chunks,
3849 vmp->vm_quantum);
3850 chunks = slabsize / chunksize;
3851 waste = (slabsize % chunksize) / chunks;
3852 if (waste < minwaste) {
3853 minwaste = waste;
3854 bestfit = slabsize;
3855 }
3856 }
3857 if (cflags & KMC_QCACHE)
3858 bestfit = VMEM_QCACHE_SLABSIZE(vmp->vm_qcache_max);
3859 cp->cache_slabsize = bestfit;
3860 cp->cache_mincolor = 0;
3861 cp->cache_maxcolor = bestfit % chunksize;
3862 cp->cache_flags |= KMF_HASH;
3863 }
3864
3865 cp->cache_maxchunks = (cp->cache_slabsize / cp->cache_chunksize);
3866 cp->cache_partial_binshift = highbit(cp->cache_maxchunks / 16) + 1;
3867
3868 /*
3869 * Disallowing prefill when either the DEBUG or HASH flag is set or when
3870 * there is a constructor avoids some tricky issues with debug setup
3871 * that may be revisited later. We cannot allow prefill in a
3872 * metadata cache because of potential recursion.
3873 */
3874 if (vmp == kmem_msb_arena ||
3875 cp->cache_flags & (KMF_HASH | KMF_BUFTAG) ||
3876 cp->cache_constructor != NULL)
3877 cp->cache_flags &= ~KMF_PREFILL;
3878
3879 if (cp->cache_flags & KMF_HASH) {
3880 ASSERT(!(cflags & KMC_NOHASH));
3881 cp->cache_bufctl_cache = (cp->cache_flags & KMF_AUDIT) ?
3882 kmem_bufctl_audit_cache : kmem_bufctl_cache;
3883 }
3884
3885 if (cp->cache_maxcolor >= vmp->vm_quantum)
3886 cp->cache_maxcolor = vmp->vm_quantum - 1;
3887
3888 cp->cache_color = cp->cache_mincolor;
3889
3890 /*
3891 * Initialize the rest of the slab layer.
3892 */
3893 mutex_init(&cp->cache_lock, NULL, MUTEX_DEFAULT, NULL);
3894
3895 avl_create(&cp->cache_partial_slabs, kmem_partial_slab_cmp,
3896 sizeof (kmem_slab_t), offsetof(kmem_slab_t, slab_link));
3897 /* LINTED: E_TRUE_LOGICAL_EXPR */
3898 ASSERT(sizeof (list_node_t) <= sizeof (avl_node_t));
3899 /* reuse partial slab AVL linkage for complete slab list linkage */
3900 list_create(&cp->cache_complete_slabs,
3901 sizeof (kmem_slab_t), offsetof(kmem_slab_t, slab_link));
3902
3903 if (cp->cache_flags & KMF_HASH) {
3904 cp->cache_hash_table = vmem_alloc(kmem_hash_arena,
3905 KMEM_HASH_INITIAL * sizeof (void *), VM_SLEEP);
3906 bzero(cp->cache_hash_table,
3907 KMEM_HASH_INITIAL * sizeof (void *));
3908 cp->cache_hash_mask = KMEM_HASH_INITIAL - 1;
3909 cp->cache_hash_shift = highbit((ulong_t)chunksize) - 1;
3910 }
3911
3912 /*
3913 * Initialize the depot.
3914 */
3915 mutex_init(&cp->cache_depot_lock, NULL, MUTEX_DEFAULT, NULL);
3916
3917 for (mtp = kmem_magtype; chunksize <= mtp->mt_minbuf; mtp++)
3918 continue;
3919
3920 cp->cache_magtype = mtp;
3921
3922 /*
3923 * Initialize the CPU layer.
3924 */
3925 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3926 kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3927 mutex_init(&ccp->cc_lock, NULL, MUTEX_DEFAULT, NULL);
3928 ccp->cc_flags = cp->cache_flags;
3929 ccp->cc_rounds = -1;
3930 ccp->cc_prounds = -1;
3931 }
3932
3933 /*
3934 * Create the cache's kstats.
3935 */
3936 if ((cp->cache_kstat = kstat_create("unix", 0, cp->cache_name,
3937 "kmem_cache", KSTAT_TYPE_NAMED,
3938 sizeof (kmem_cache_kstat) / sizeof (kstat_named_t),
3939 KSTAT_FLAG_VIRTUAL)) != NULL) {
3940 cp->cache_kstat->ks_data = &kmem_cache_kstat;
3941 cp->cache_kstat->ks_update = kmem_cache_kstat_update;
3942 cp->cache_kstat->ks_private = cp;
3943 cp->cache_kstat->ks_lock = &kmem_cache_kstat_lock;
3944 kstat_install(cp->cache_kstat);
3945 }
3946
3947 /*
3948 * Add the cache to the global list. This makes it visible
3949 * to kmem_update(), so the cache must be ready for business.
3950 */
3951 mutex_enter(&kmem_cache_lock);
3952 list_insert_tail(&kmem_caches, cp);
3953 mutex_exit(&kmem_cache_lock);
3954
3955 if (kmem_ready)
3956 kmem_cache_magazine_enable(cp);
3957
3958 return (cp);
3959 }
3960
3961 static int
kmem_move_cmp(const void * buf,const void * p)3962 kmem_move_cmp(const void *buf, const void *p)
3963 {
3964 const kmem_move_t *kmm = p;
3965 uintptr_t v1 = (uintptr_t)buf;
3966 uintptr_t v2 = (uintptr_t)kmm->kmm_from_buf;
3967 return (v1 < v2 ? -1 : (v1 > v2 ? 1 : 0));
3968 }
3969
3970 static void
kmem_reset_reclaim_threshold(kmem_defrag_t * kmd)3971 kmem_reset_reclaim_threshold(kmem_defrag_t *kmd)
3972 {
3973 kmd->kmd_reclaim_numer = 1;
3974 }
3975
3976 /*
3977 * Initially, when choosing candidate slabs for buffers to move, we want to be
3978 * very selective and take only slabs that are less than
3979 * (1 / KMEM_VOID_FRACTION) allocated. If we have difficulty finding candidate
3980 * slabs, then we raise the allocation ceiling incrementally. The reclaim
3981 * threshold is reset to (1 / KMEM_VOID_FRACTION) as soon as the cache is no
3982 * longer fragmented.
3983 */
3984 static void
kmem_adjust_reclaim_threshold(kmem_defrag_t * kmd,int direction)3985 kmem_adjust_reclaim_threshold(kmem_defrag_t *kmd, int direction)
3986 {
3987 if (direction > 0) {
3988 /* make it easier to find a candidate slab */
3989 if (kmd->kmd_reclaim_numer < (KMEM_VOID_FRACTION - 1)) {
3990 kmd->kmd_reclaim_numer++;
3991 }
3992 } else {
3993 /* be more selective */
3994 if (kmd->kmd_reclaim_numer > 1) {
3995 kmd->kmd_reclaim_numer--;
3996 }
3997 }
3998 }
3999
4000 void
kmem_cache_set_move(kmem_cache_t * cp,kmem_cbrc_t (* move)(void *,void *,size_t,void *))4001 kmem_cache_set_move(kmem_cache_t *cp,
4002 kmem_cbrc_t (*move)(void *, void *, size_t, void *))
4003 {
4004 kmem_defrag_t *defrag;
4005
4006 ASSERT(move != NULL);
4007 /*
4008 * The consolidator does not support NOTOUCH caches because kmem cannot
4009 * initialize their slabs with the 0xbaddcafe memory pattern, which sets
4010 * a low order bit usable by clients to distinguish uninitialized memory
4011 * from known objects (see kmem_slab_create).
4012 */
4013 ASSERT(!(cp->cache_cflags & KMC_NOTOUCH));
4014 ASSERT(!(cp->cache_cflags & KMC_IDENTIFIER));
4015
4016 /*
4017 * We should not be holding anyone's cache lock when calling
4018 * kmem_cache_alloc(), so allocate in all cases before acquiring the
4019 * lock.
4020 */
4021 defrag = kmem_cache_alloc(kmem_defrag_cache, KM_SLEEP);
4022
4023 mutex_enter(&cp->cache_lock);
4024
4025 if (KMEM_IS_MOVABLE(cp)) {
4026 if (cp->cache_move == NULL) {
4027 ASSERT(cp->cache_slab_alloc == 0);
4028
4029 cp->cache_defrag = defrag;
4030 defrag = NULL; /* nothing to free */
4031 bzero(cp->cache_defrag, sizeof (kmem_defrag_t));
4032 avl_create(&cp->cache_defrag->kmd_moves_pending,
4033 kmem_move_cmp, sizeof (kmem_move_t),
4034 offsetof(kmem_move_t, kmm_entry));
4035 /* LINTED: E_TRUE_LOGICAL_EXPR */
4036 ASSERT(sizeof (list_node_t) <= sizeof (avl_node_t));
4037 /* reuse the slab's AVL linkage for deadlist linkage */
4038 list_create(&cp->cache_defrag->kmd_deadlist,
4039 sizeof (kmem_slab_t),
4040 offsetof(kmem_slab_t, slab_link));
4041 kmem_reset_reclaim_threshold(cp->cache_defrag);
4042 }
4043 cp->cache_move = move;
4044 }
4045
4046 mutex_exit(&cp->cache_lock);
4047
4048 if (defrag != NULL) {
4049 kmem_cache_free(kmem_defrag_cache, defrag); /* unused */
4050 }
4051 }
4052
4053 void
kmem_cache_destroy(kmem_cache_t * cp)4054 kmem_cache_destroy(kmem_cache_t *cp)
4055 {
4056 int cpu_seqid;
4057
4058 /*
4059 * Remove the cache from the global cache list so that no one else
4060 * can schedule tasks on its behalf, wait for any pending tasks to
4061 * complete, purge the cache, and then destroy it.
4062 */
4063 mutex_enter(&kmem_cache_lock);
4064 list_remove(&kmem_caches, cp);
4065 mutex_exit(&kmem_cache_lock);
4066
4067 if (kmem_taskq != NULL)
4068 taskq_wait(kmem_taskq);
4069 if (kmem_move_taskq != NULL)
4070 taskq_wait(kmem_move_taskq);
4071
4072 kmem_cache_magazine_purge(cp);
4073
4074 mutex_enter(&cp->cache_lock);
4075 if (cp->cache_buftotal != 0)
4076 cmn_err(CE_WARN, "kmem_cache_destroy: '%s' (%p) not empty",
4077 cp->cache_name, (void *)cp);
4078 if (cp->cache_defrag != NULL) {
4079 avl_destroy(&cp->cache_defrag->kmd_moves_pending);
4080 list_destroy(&cp->cache_defrag->kmd_deadlist);
4081 kmem_cache_free(kmem_defrag_cache, cp->cache_defrag);
4082 cp->cache_defrag = NULL;
4083 }
4084 /*
4085 * The cache is now dead. There should be no further activity. We
4086 * enforce this by setting land mines in the constructor, destructor,
4087 * reclaim, and move routines that induce a kernel text fault if
4088 * invoked.
4089 */
4090 cp->cache_constructor = (int (*)(void *, void *, int))1;
4091 cp->cache_destructor = (void (*)(void *, void *))2;
4092 cp->cache_reclaim = (void (*)(void *))3;
4093 cp->cache_move = (kmem_cbrc_t (*)(void *, void *, size_t, void *))4;
4094 mutex_exit(&cp->cache_lock);
4095
4096 kstat_delete(cp->cache_kstat);
4097
4098 if (cp->cache_hash_table != NULL)
4099 vmem_free(kmem_hash_arena, cp->cache_hash_table,
4100 (cp->cache_hash_mask + 1) * sizeof (void *));
4101
4102 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++)
4103 mutex_destroy(&cp->cache_cpu[cpu_seqid].cc_lock);
4104
4105 mutex_destroy(&cp->cache_depot_lock);
4106 mutex_destroy(&cp->cache_lock);
4107
4108 vmem_free(kmem_cache_arena, cp, KMEM_CACHE_SIZE(max_ncpus));
4109 }
4110
4111 /*ARGSUSED*/
4112 static int
kmem_cpu_setup(cpu_setup_t what,int id,void * arg)4113 kmem_cpu_setup(cpu_setup_t what, int id, void *arg)
4114 {
4115 ASSERT(MUTEX_HELD(&cpu_lock));
4116 if (what == CPU_UNCONFIG) {
4117 kmem_cache_applyall(kmem_cache_magazine_purge,
4118 kmem_taskq, TQ_SLEEP);
4119 kmem_cache_applyall(kmem_cache_magazine_enable,
4120 kmem_taskq, TQ_SLEEP);
4121 }
4122 return (0);
4123 }
4124
4125 static void
kmem_alloc_caches_create(const int * array,size_t count,kmem_cache_t ** alloc_table,size_t maxbuf,uint_t shift)4126 kmem_alloc_caches_create(const int *array, size_t count,
4127 kmem_cache_t **alloc_table, size_t maxbuf, uint_t shift)
4128 {
4129 char name[KMEM_CACHE_NAMELEN + 1];
4130 size_t table_unit = (1 << shift); /* range of one alloc_table entry */
4131 size_t size = table_unit;
4132 int i;
4133
4134 for (i = 0; i < count; i++) {
4135 size_t cache_size = array[i];
4136 size_t align = KMEM_ALIGN;
4137 kmem_cache_t *cp;
4138
4139 /* if the table has an entry for maxbuf, we're done */
4140 if (size > maxbuf)
4141 break;
4142
4143 /* cache size must be a multiple of the table unit */
4144 ASSERT(P2PHASE(cache_size, table_unit) == 0);
4145
4146 /*
4147 * If they allocate a multiple of the coherency granularity,
4148 * they get a coherency-granularity-aligned address.
4149 */
4150 if (IS_P2ALIGNED(cache_size, 64))
4151 align = 64;
4152 if (IS_P2ALIGNED(cache_size, PAGESIZE))
4153 align = PAGESIZE;
4154 (void) snprintf(name, sizeof (name),
4155 "kmem_alloc_%lu", cache_size);
4156 cp = kmem_cache_create(name, cache_size, align,
4157 NULL, NULL, NULL, NULL, NULL, KMC_KMEM_ALLOC);
4158
4159 while (size <= cache_size) {
4160 alloc_table[(size - 1) >> shift] = cp;
4161 size += table_unit;
4162 }
4163 }
4164
4165 ASSERT(size > maxbuf); /* i.e. maxbuf <= max(cache_size) */
4166 }
4167
4168 static void
kmem_cache_init(int pass,int use_large_pages)4169 kmem_cache_init(int pass, int use_large_pages)
4170 {
4171 int i;
4172 size_t maxbuf;
4173 kmem_magtype_t *mtp;
4174
4175 for (i = 0; i < sizeof (kmem_magtype) / sizeof (*mtp); i++) {
4176 char name[KMEM_CACHE_NAMELEN + 1];
4177
4178 mtp = &kmem_magtype[i];
4179 (void) sprintf(name, "kmem_magazine_%d", mtp->mt_magsize);
4180 mtp->mt_cache = kmem_cache_create(name,
4181 (mtp->mt_magsize + 1) * sizeof (void *),
4182 mtp->mt_align, NULL, NULL, NULL, NULL,
4183 kmem_msb_arena, KMC_NOHASH);
4184 }
4185
4186 kmem_slab_cache = kmem_cache_create("kmem_slab_cache",
4187 sizeof (kmem_slab_t), 0, NULL, NULL, NULL, NULL,
4188 kmem_msb_arena, KMC_NOHASH);
4189
4190 kmem_bufctl_cache = kmem_cache_create("kmem_bufctl_cache",
4191 sizeof (kmem_bufctl_t), 0, NULL, NULL, NULL, NULL,
4192 kmem_msb_arena, KMC_NOHASH);
4193
4194 kmem_bufctl_audit_cache = kmem_cache_create("kmem_bufctl_audit_cache",
4195 sizeof (kmem_bufctl_audit_t), 0, NULL, NULL, NULL, NULL,
4196 kmem_msb_arena, KMC_NOHASH);
4197
4198 if (pass == 2) {
4199 kmem_va_arena = vmem_create("kmem_va",
4200 NULL, 0, PAGESIZE,
4201 vmem_alloc, vmem_free, heap_arena,
4202 8 * PAGESIZE, VM_SLEEP);
4203
4204 if (use_large_pages) {
4205 kmem_default_arena = vmem_xcreate("kmem_default",
4206 NULL, 0, PAGESIZE,
4207 segkmem_alloc_lp, segkmem_free_lp, kmem_va_arena,
4208 0, VMC_DUMPSAFE | VM_SLEEP);
4209 } else {
4210 kmem_default_arena = vmem_create("kmem_default",
4211 NULL, 0, PAGESIZE,
4212 segkmem_alloc, segkmem_free, kmem_va_arena,
4213 0, VMC_DUMPSAFE | VM_SLEEP);
4214 }
4215
4216 /* Figure out what our maximum cache size is */
4217 maxbuf = kmem_max_cached;
4218 if (maxbuf <= KMEM_MAXBUF) {
4219 maxbuf = 0;
4220 kmem_max_cached = KMEM_MAXBUF;
4221 } else {
4222 size_t size = 0;
4223 size_t max =
4224 sizeof (kmem_big_alloc_sizes) / sizeof (int);
4225 /*
4226 * Round maxbuf up to an existing cache size. If maxbuf
4227 * is larger than the largest cache, we truncate it to
4228 * the largest cache's size.
4229 */
4230 for (i = 0; i < max; i++) {
4231 size = kmem_big_alloc_sizes[i];
4232 if (maxbuf <= size)
4233 break;
4234 }
4235 kmem_max_cached = maxbuf = size;
4236 }
4237
4238 /*
4239 * The big alloc table may not be completely overwritten, so
4240 * we clear out any stale cache pointers from the first pass.
4241 */
4242 bzero(kmem_big_alloc_table, sizeof (kmem_big_alloc_table));
4243 } else {
4244 /*
4245 * During the first pass, the kmem_alloc_* caches
4246 * are treated as metadata.
4247 */
4248 kmem_default_arena = kmem_msb_arena;
4249 maxbuf = KMEM_BIG_MAXBUF_32BIT;
4250 }
4251
4252 /*
4253 * Set up the default caches to back kmem_alloc()
4254 */
4255 kmem_alloc_caches_create(
4256 kmem_alloc_sizes, sizeof (kmem_alloc_sizes) / sizeof (int),
4257 kmem_alloc_table, KMEM_MAXBUF, KMEM_ALIGN_SHIFT);
4258
4259 kmem_alloc_caches_create(
4260 kmem_big_alloc_sizes, sizeof (kmem_big_alloc_sizes) / sizeof (int),
4261 kmem_big_alloc_table, maxbuf, KMEM_BIG_SHIFT);
4262
4263 kmem_big_alloc_table_max = maxbuf >> KMEM_BIG_SHIFT;
4264 }
4265
4266 void
kmem_init(void)4267 kmem_init(void)
4268 {
4269 kmem_cache_t *cp;
4270 int old_kmem_flags = kmem_flags;
4271 int use_large_pages = 0;
4272 size_t maxverify, minfirewall;
4273
4274 kstat_init();
4275
4276 /*
4277 * Don't do firewalled allocations if the heap is less than 1TB
4278 * (i.e. on a 32-bit kernel)
4279 * The resulting VM_NEXTFIT allocations would create too much
4280 * fragmentation in a small heap.
4281 */
4282 #if defined(_LP64)
4283 maxverify = minfirewall = PAGESIZE / 2;
4284 #else
4285 maxverify = minfirewall = ULONG_MAX;
4286 #endif
4287
4288 /* LINTED */
4289 ASSERT(sizeof (kmem_cpu_cache_t) == KMEM_CPU_CACHE_SIZE);
4290
4291 list_create(&kmem_caches, sizeof (kmem_cache_t),
4292 offsetof(kmem_cache_t, cache_link));
4293
4294 kmem_metadata_arena = vmem_create("kmem_metadata", NULL, 0, PAGESIZE,
4295 vmem_alloc, vmem_free, heap_arena, 8 * PAGESIZE,
4296 VM_SLEEP | VMC_NO_QCACHE);
4297
4298 kmem_msb_arena = vmem_create("kmem_msb", NULL, 0,
4299 PAGESIZE, segkmem_alloc, segkmem_free, kmem_metadata_arena, 0,
4300 VMC_DUMPSAFE | VM_SLEEP);
4301
4302 kmem_cache_arena = vmem_create("kmem_cache", NULL, 0, KMEM_ALIGN,
4303 segkmem_alloc, segkmem_free, kmem_metadata_arena, 0, VM_SLEEP);
4304
4305 kmem_hash_arena = vmem_create("kmem_hash", NULL, 0, KMEM_ALIGN,
4306 segkmem_alloc, segkmem_free, kmem_metadata_arena, 0, VM_SLEEP);
4307
4308 kmem_log_arena = vmem_create("kmem_log", NULL, 0, KMEM_ALIGN,
4309 segkmem_alloc, segkmem_free, heap_arena, 0, VM_SLEEP);
4310
4311 kmem_firewall_va_arena = vmem_create("kmem_firewall_va",
4312 NULL, 0, PAGESIZE,
4313 kmem_firewall_va_alloc, kmem_firewall_va_free, heap_arena,
4314 0, VM_SLEEP);
4315
4316 kmem_firewall_arena = vmem_create("kmem_firewall", NULL, 0, PAGESIZE,
4317 segkmem_alloc, segkmem_free, kmem_firewall_va_arena, 0,
4318 VMC_DUMPSAFE | VM_SLEEP);
4319
4320 /* temporary oversize arena for mod_read_system_file */
4321 kmem_oversize_arena = vmem_create("kmem_oversize", NULL, 0, PAGESIZE,
4322 segkmem_alloc, segkmem_free, heap_arena, 0, VM_SLEEP);
4323
4324 kmem_reap_interval = 15 * hz;
4325
4326 /*
4327 * Read /etc/system. This is a chicken-and-egg problem because
4328 * kmem_flags may be set in /etc/system, but mod_read_system_file()
4329 * needs to use the allocator. The simplest solution is to create
4330 * all the standard kmem caches, read /etc/system, destroy all the
4331 * caches we just created, and then create them all again in light
4332 * of the (possibly) new kmem_flags and other kmem tunables.
4333 */
4334 kmem_cache_init(1, 0);
4335
4336 mod_read_system_file(boothowto & RB_ASKNAME);
4337
4338 while ((cp = list_tail(&kmem_caches)) != NULL)
4339 kmem_cache_destroy(cp);
4340
4341 vmem_destroy(kmem_oversize_arena);
4342
4343 if (old_kmem_flags & KMF_STICKY)
4344 kmem_flags = old_kmem_flags;
4345
4346 if (!(kmem_flags & KMF_AUDIT))
4347 vmem_seg_size = offsetof(vmem_seg_t, vs_thread);
4348
4349 if (kmem_maxverify == 0)
4350 kmem_maxverify = maxverify;
4351
4352 if (kmem_minfirewall == 0)
4353 kmem_minfirewall = minfirewall;
4354
4355 /*
4356 * give segkmem a chance to figure out if we are using large pages
4357 * for the kernel heap
4358 */
4359 use_large_pages = segkmem_lpsetup();
4360
4361 /*
4362 * To protect against corruption, we keep the actual number of callers
4363 * KMF_LITE records seperate from the tunable. We arbitrarily clamp
4364 * to 16, since the overhead for small buffers quickly gets out of
4365 * hand.
4366 *
4367 * The real limit would depend on the needs of the largest KMC_NOHASH
4368 * cache.
4369 */
4370 kmem_lite_count = MIN(MAX(0, kmem_lite_pcs), 16);
4371 kmem_lite_pcs = kmem_lite_count;
4372
4373 /*
4374 * Normally, we firewall oversized allocations when possible, but
4375 * if we are using large pages for kernel memory, and we don't have
4376 * any non-LITE debugging flags set, we want to allocate oversized
4377 * buffers from large pages, and so skip the firewalling.
4378 */
4379 if (use_large_pages &&
4380 ((kmem_flags & KMF_LITE) || !(kmem_flags & KMF_DEBUG))) {
4381 kmem_oversize_arena = vmem_xcreate("kmem_oversize", NULL, 0,
4382 PAGESIZE, segkmem_alloc_lp, segkmem_free_lp, heap_arena,
4383 0, VMC_DUMPSAFE | VM_SLEEP);
4384 } else {
4385 kmem_oversize_arena = vmem_create("kmem_oversize",
4386 NULL, 0, PAGESIZE,
4387 segkmem_alloc, segkmem_free, kmem_minfirewall < ULONG_MAX?
4388 kmem_firewall_va_arena : heap_arena, 0, VMC_DUMPSAFE |
4389 VM_SLEEP);
4390 }
4391
4392 kmem_cache_init(2, use_large_pages);
4393
4394 if (kmem_flags & (KMF_AUDIT | KMF_RANDOMIZE)) {
4395 if (kmem_transaction_log_size == 0)
4396 kmem_transaction_log_size = kmem_maxavail() / 50;
4397 kmem_transaction_log = kmem_log_init(kmem_transaction_log_size);
4398 }
4399
4400 if (kmem_flags & (KMF_CONTENTS | KMF_RANDOMIZE)) {
4401 if (kmem_content_log_size == 0)
4402 kmem_content_log_size = kmem_maxavail() / 50;
4403 kmem_content_log = kmem_log_init(kmem_content_log_size);
4404 }
4405
4406 kmem_failure_log = kmem_log_init(kmem_failure_log_size);
4407
4408 kmem_slab_log = kmem_log_init(kmem_slab_log_size);
4409
4410 /*
4411 * Initialize STREAMS message caches so allocb() is available.
4412 * This allows us to initialize the logging framework (cmn_err(9F),
4413 * strlog(9F), etc) so we can start recording messages.
4414 */
4415 streams_msg_init();
4416
4417 /*
4418 * Initialize the ZSD framework in Zones so modules loaded henceforth
4419 * can register their callbacks.
4420 */
4421 zone_zsd_init();
4422
4423 log_init();
4424 taskq_init();
4425
4426 /*
4427 * Warn about invalid or dangerous values of kmem_flags.
4428 * Always warn about unsupported values.
4429 */
4430 if (((kmem_flags & ~(KMF_AUDIT | KMF_DEADBEEF | KMF_REDZONE |
4431 KMF_CONTENTS | KMF_LITE)) != 0) ||
4432 ((kmem_flags & KMF_LITE) && kmem_flags != KMF_LITE))
4433 cmn_err(CE_WARN, "kmem_flags set to unsupported value 0x%x. "
4434 "See the Solaris Tunable Parameters Reference Manual.",
4435 kmem_flags);
4436
4437 #ifdef DEBUG
4438 if ((kmem_flags & KMF_DEBUG) == 0)
4439 cmn_err(CE_NOTE, "kmem debugging disabled.");
4440 #else
4441 /*
4442 * For non-debug kernels, the only "normal" flags are 0, KMF_LITE,
4443 * KMF_REDZONE, and KMF_CONTENTS (the last because it is only enabled
4444 * if KMF_AUDIT is set). We should warn the user about the performance
4445 * penalty of KMF_AUDIT or KMF_DEADBEEF if they are set and KMF_LITE
4446 * isn't set (since that disables AUDIT).
4447 */
4448 if (!(kmem_flags & KMF_LITE) &&
4449 (kmem_flags & (KMF_AUDIT | KMF_DEADBEEF)) != 0)
4450 cmn_err(CE_WARN, "High-overhead kmem debugging features "
4451 "enabled (kmem_flags = 0x%x). Performance degradation "
4452 "and large memory overhead possible. See the Solaris "
4453 "Tunable Parameters Reference Manual.", kmem_flags);
4454 #endif /* not DEBUG */
4455
4456 kmem_cache_applyall(kmem_cache_magazine_enable, NULL, TQ_SLEEP);
4457
4458 kmem_ready = 1;
4459
4460 /*
4461 * Initialize the platform-specific aligned/DMA memory allocator.
4462 */
4463 ka_init();
4464
4465 /*
4466 * Initialize 32-bit ID cache.
4467 */
4468 id32_init();
4469
4470 /*
4471 * Initialize the networking stack so modules loaded can
4472 * register their callbacks.
4473 */
4474 netstack_init();
4475 }
4476
4477 static void
kmem_move_init(void)4478 kmem_move_init(void)
4479 {
4480 kmem_defrag_cache = kmem_cache_create("kmem_defrag_cache",
4481 sizeof (kmem_defrag_t), 0, NULL, NULL, NULL, NULL,
4482 kmem_msb_arena, KMC_NOHASH);
4483 kmem_move_cache = kmem_cache_create("kmem_move_cache",
4484 sizeof (kmem_move_t), 0, NULL, NULL, NULL, NULL,
4485 kmem_msb_arena, KMC_NOHASH);
4486
4487 /*
4488 * kmem guarantees that move callbacks are sequential and that even
4489 * across multiple caches no two moves ever execute simultaneously.
4490 * Move callbacks are processed on a separate taskq so that client code
4491 * does not interfere with internal maintenance tasks.
4492 */
4493 kmem_move_taskq = taskq_create_instance("kmem_move_taskq", 0, 1,
4494 minclsyspri, 100, INT_MAX, TASKQ_PREPOPULATE);
4495 }
4496
4497 void
kmem_thread_init(void)4498 kmem_thread_init(void)
4499 {
4500 kmem_move_init();
4501 kmem_taskq = taskq_create_instance("kmem_taskq", 0, 1, minclsyspri,
4502 300, INT_MAX, TASKQ_PREPOPULATE);
4503 }
4504
4505 void
kmem_mp_init(void)4506 kmem_mp_init(void)
4507 {
4508 mutex_enter(&cpu_lock);
4509 register_cpu_setup_func(kmem_cpu_setup, NULL);
4510 mutex_exit(&cpu_lock);
4511
4512 kmem_update_timeout(NULL);
4513
4514 taskq_mp_init();
4515 }
4516
4517 /*
4518 * Return the slab of the allocated buffer, or NULL if the buffer is not
4519 * allocated. This function may be called with a known slab address to determine
4520 * whether or not the buffer is allocated, or with a NULL slab address to obtain
4521 * an allocated buffer's slab.
4522 */
4523 static kmem_slab_t *
kmem_slab_allocated(kmem_cache_t * cp,kmem_slab_t * sp,void * buf)4524 kmem_slab_allocated(kmem_cache_t *cp, kmem_slab_t *sp, void *buf)
4525 {
4526 kmem_bufctl_t *bcp, *bufbcp;
4527
4528 ASSERT(MUTEX_HELD(&cp->cache_lock));
4529 ASSERT(sp == NULL || KMEM_SLAB_MEMBER(sp, buf));
4530
4531 if (cp->cache_flags & KMF_HASH) {
4532 for (bcp = *KMEM_HASH(cp, buf);
4533 (bcp != NULL) && (bcp->bc_addr != buf);
4534 bcp = bcp->bc_next) {
4535 continue;
4536 }
4537 ASSERT(sp != NULL && bcp != NULL ? sp == bcp->bc_slab : 1);
4538 return (bcp == NULL ? NULL : bcp->bc_slab);
4539 }
4540
4541 if (sp == NULL) {
4542 sp = KMEM_SLAB(cp, buf);
4543 }
4544 bufbcp = KMEM_BUFCTL(cp, buf);
4545 for (bcp = sp->slab_head;
4546 (bcp != NULL) && (bcp != bufbcp);
4547 bcp = bcp->bc_next) {
4548 continue;
4549 }
4550 return (bcp == NULL ? sp : NULL);
4551 }
4552
4553 static boolean_t
kmem_slab_is_reclaimable(kmem_cache_t * cp,kmem_slab_t * sp,int flags)4554 kmem_slab_is_reclaimable(kmem_cache_t *cp, kmem_slab_t *sp, int flags)
4555 {
4556 long refcnt = sp->slab_refcnt;
4557
4558 ASSERT(cp->cache_defrag != NULL);
4559
4560 /*
4561 * For code coverage we want to be able to move an object within the
4562 * same slab (the only partial slab) even if allocating the destination
4563 * buffer resulted in a completely allocated slab.
4564 */
4565 if (flags & KMM_DEBUG) {
4566 return ((flags & KMM_DESPERATE) ||
4567 ((sp->slab_flags & KMEM_SLAB_NOMOVE) == 0));
4568 }
4569
4570 /* If we're desperate, we don't care if the client said NO. */
4571 if (flags & KMM_DESPERATE) {
4572 return (refcnt < sp->slab_chunks); /* any partial */
4573 }
4574
4575 if (sp->slab_flags & KMEM_SLAB_NOMOVE) {
4576 return (B_FALSE);
4577 }
4578
4579 if ((refcnt == 1) || kmem_move_any_partial) {
4580 return (refcnt < sp->slab_chunks);
4581 }
4582
4583 /*
4584 * The reclaim threshold is adjusted at each kmem_cache_scan() so that
4585 * slabs with a progressively higher percentage of used buffers can be
4586 * reclaimed until the cache as a whole is no longer fragmented.
4587 *
4588 * sp->slab_refcnt kmd_reclaim_numer
4589 * --------------- < ------------------
4590 * sp->slab_chunks KMEM_VOID_FRACTION
4591 */
4592 return ((refcnt * KMEM_VOID_FRACTION) <
4593 (sp->slab_chunks * cp->cache_defrag->kmd_reclaim_numer));
4594 }
4595
4596 static void *
kmem_hunt_mag(kmem_cache_t * cp,kmem_magazine_t * m,int n,void * buf,void * tbuf)4597 kmem_hunt_mag(kmem_cache_t *cp, kmem_magazine_t *m, int n, void *buf,
4598 void *tbuf)
4599 {
4600 int i; /* magazine round index */
4601
4602 for (i = 0; i < n; i++) {
4603 if (buf == m->mag_round[i]) {
4604 if (cp->cache_flags & KMF_BUFTAG) {
4605 (void) kmem_cache_free_debug(cp, tbuf,
4606 caller());
4607 }
4608 m->mag_round[i] = tbuf;
4609 return (buf);
4610 }
4611 }
4612
4613 return (NULL);
4614 }
4615
4616 /*
4617 * Hunt the magazine layer for the given buffer. If found, the buffer is
4618 * removed from the magazine layer and returned, otherwise NULL is returned.
4619 * The state of the returned buffer is freed and constructed.
4620 */
4621 static void *
kmem_hunt_mags(kmem_cache_t * cp,void * buf)4622 kmem_hunt_mags(kmem_cache_t *cp, void *buf)
4623 {
4624 kmem_cpu_cache_t *ccp;
4625 kmem_magazine_t *m;
4626 int cpu_seqid;
4627 int n; /* magazine rounds */
4628 void *tbuf; /* temporary swap buffer */
4629
4630 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4631
4632 /*
4633 * Allocated a buffer to swap with the one we hope to pull out of a
4634 * magazine when found.
4635 */
4636 tbuf = kmem_cache_alloc(cp, KM_NOSLEEP);
4637 if (tbuf == NULL) {
4638 KMEM_STAT_ADD(kmem_move_stats.kms_hunt_alloc_fail);
4639 return (NULL);
4640 }
4641 if (tbuf == buf) {
4642 KMEM_STAT_ADD(kmem_move_stats.kms_hunt_lucky);
4643 if (cp->cache_flags & KMF_BUFTAG) {
4644 (void) kmem_cache_free_debug(cp, buf, caller());
4645 }
4646 return (buf);
4647 }
4648
4649 /* Hunt the depot. */
4650 mutex_enter(&cp->cache_depot_lock);
4651 n = cp->cache_magtype->mt_magsize;
4652 for (m = cp->cache_full.ml_list; m != NULL; m = m->mag_next) {
4653 if (kmem_hunt_mag(cp, m, n, buf, tbuf) != NULL) {
4654 mutex_exit(&cp->cache_depot_lock);
4655 return (buf);
4656 }
4657 }
4658 mutex_exit(&cp->cache_depot_lock);
4659
4660 /* Hunt the per-CPU magazines. */
4661 for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
4662 ccp = &cp->cache_cpu[cpu_seqid];
4663
4664 mutex_enter(&ccp->cc_lock);
4665 m = ccp->cc_loaded;
4666 n = ccp->cc_rounds;
4667 if (kmem_hunt_mag(cp, m, n, buf, tbuf) != NULL) {
4668 mutex_exit(&ccp->cc_lock);
4669 return (buf);
4670 }
4671 m = ccp->cc_ploaded;
4672 n = ccp->cc_prounds;
4673 if (kmem_hunt_mag(cp, m, n, buf, tbuf) != NULL) {
4674 mutex_exit(&ccp->cc_lock);
4675 return (buf);
4676 }
4677 mutex_exit(&ccp->cc_lock);
4678 }
4679
4680 kmem_cache_free(cp, tbuf);
4681 return (NULL);
4682 }
4683
4684 /*
4685 * May be called from the kmem_move_taskq, from kmem_cache_move_notify_task(),
4686 * or when the buffer is freed.
4687 */
4688 static void
kmem_slab_move_yes(kmem_cache_t * cp,kmem_slab_t * sp,void * from_buf)4689 kmem_slab_move_yes(kmem_cache_t *cp, kmem_slab_t *sp, void *from_buf)
4690 {
4691 ASSERT(MUTEX_HELD(&cp->cache_lock));
4692 ASSERT(KMEM_SLAB_MEMBER(sp, from_buf));
4693
4694 if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4695 return;
4696 }
4697
4698 if (sp->slab_flags & KMEM_SLAB_NOMOVE) {
4699 if (KMEM_SLAB_OFFSET(sp, from_buf) == sp->slab_stuck_offset) {
4700 avl_remove(&cp->cache_partial_slabs, sp);
4701 sp->slab_flags &= ~KMEM_SLAB_NOMOVE;
4702 sp->slab_stuck_offset = (uint32_t)-1;
4703 avl_add(&cp->cache_partial_slabs, sp);
4704 }
4705 } else {
4706 sp->slab_later_count = 0;
4707 sp->slab_stuck_offset = (uint32_t)-1;
4708 }
4709 }
4710
4711 static void
kmem_slab_move_no(kmem_cache_t * cp,kmem_slab_t * sp,void * from_buf)4712 kmem_slab_move_no(kmem_cache_t *cp, kmem_slab_t *sp, void *from_buf)
4713 {
4714 ASSERT(taskq_member(kmem_move_taskq, curthread));
4715 ASSERT(MUTEX_HELD(&cp->cache_lock));
4716 ASSERT(KMEM_SLAB_MEMBER(sp, from_buf));
4717
4718 if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4719 return;
4720 }
4721
4722 avl_remove(&cp->cache_partial_slabs, sp);
4723 sp->slab_later_count = 0;
4724 sp->slab_flags |= KMEM_SLAB_NOMOVE;
4725 sp->slab_stuck_offset = KMEM_SLAB_OFFSET(sp, from_buf);
4726 avl_add(&cp->cache_partial_slabs, sp);
4727 }
4728
4729 static void kmem_move_end(kmem_cache_t *, kmem_move_t *);
4730
4731 /*
4732 * The move callback takes two buffer addresses, the buffer to be moved, and a
4733 * newly allocated and constructed buffer selected by kmem as the destination.
4734 * It also takes the size of the buffer and an optional user argument specified
4735 * at cache creation time. kmem guarantees that the buffer to be moved has not
4736 * been unmapped by the virtual memory subsystem. Beyond that, it cannot
4737 * guarantee the present whereabouts of the buffer to be moved, so it is up to
4738 * the client to safely determine whether or not it is still using the buffer.
4739 * The client must not free either of the buffers passed to the move callback,
4740 * since kmem wants to free them directly to the slab layer. The client response
4741 * tells kmem which of the two buffers to free:
4742 *
4743 * YES kmem frees the old buffer (the move was successful)
4744 * NO kmem frees the new buffer, marks the slab of the old buffer
4745 * non-reclaimable to avoid bothering the client again
4746 * LATER kmem frees the new buffer, increments slab_later_count
4747 * DONT_KNOW kmem frees the new buffer, searches mags for the old buffer
4748 * DONT_NEED kmem frees both the old buffer and the new buffer
4749 *
4750 * The pending callback argument now being processed contains both of the
4751 * buffers (old and new) passed to the move callback function, the slab of the
4752 * old buffer, and flags related to the move request, such as whether or not the
4753 * system was desperate for memory.
4754 *
4755 * Slabs are not freed while there is a pending callback, but instead are kept
4756 * on a deadlist, which is drained after the last callback completes. This means
4757 * that slabs are safe to access until kmem_move_end(), no matter how many of
4758 * their buffers have been freed. Once slab_refcnt reaches zero, it stays at
4759 * zero for as long as the slab remains on the deadlist and until the slab is
4760 * freed.
4761 */
4762 static void
kmem_move_buffer(kmem_move_t * callback)4763 kmem_move_buffer(kmem_move_t *callback)
4764 {
4765 kmem_cbrc_t response;
4766 kmem_slab_t *sp = callback->kmm_from_slab;
4767 kmem_cache_t *cp = sp->slab_cache;
4768 boolean_t free_on_slab;
4769
4770 ASSERT(taskq_member(kmem_move_taskq, curthread));
4771 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4772 ASSERT(KMEM_SLAB_MEMBER(sp, callback->kmm_from_buf));
4773
4774 /*
4775 * The number of allocated buffers on the slab may have changed since we
4776 * last checked the slab's reclaimability (when the pending move was
4777 * enqueued), or the client may have responded NO when asked to move
4778 * another buffer on the same slab.
4779 */
4780 if (!kmem_slab_is_reclaimable(cp, sp, callback->kmm_flags)) {
4781 KMEM_STAT_ADD(kmem_move_stats.kms_no_longer_reclaimable);
4782 KMEM_STAT_COND_ADD((callback->kmm_flags & KMM_NOTIFY),
4783 kmem_move_stats.kms_notify_no_longer_reclaimable);
4784 kmem_slab_free(cp, callback->kmm_to_buf);
4785 kmem_move_end(cp, callback);
4786 return;
4787 }
4788
4789 /*
4790 * Hunting magazines is expensive, so we'll wait to do that until the
4791 * client responds KMEM_CBRC_DONT_KNOW. However, checking the slab layer
4792 * is cheap, so we might as well do that here in case we can avoid
4793 * bothering the client.
4794 */
4795 mutex_enter(&cp->cache_lock);
4796 free_on_slab = (kmem_slab_allocated(cp, sp,
4797 callback->kmm_from_buf) == NULL);
4798 mutex_exit(&cp->cache_lock);
4799
4800 if (free_on_slab) {
4801 KMEM_STAT_ADD(kmem_move_stats.kms_hunt_found_slab);
4802 kmem_slab_free(cp, callback->kmm_to_buf);
4803 kmem_move_end(cp, callback);
4804 return;
4805 }
4806
4807 if (cp->cache_flags & KMF_BUFTAG) {
4808 /*
4809 * Make kmem_cache_alloc_debug() apply the constructor for us.
4810 */
4811 if (kmem_cache_alloc_debug(cp, callback->kmm_to_buf,
4812 KM_NOSLEEP, 1, caller()) != 0) {
4813 KMEM_STAT_ADD(kmem_move_stats.kms_alloc_fail);
4814 kmem_move_end(cp, callback);
4815 return;
4816 }
4817 } else if (cp->cache_constructor != NULL &&
4818 cp->cache_constructor(callback->kmm_to_buf, cp->cache_private,
4819 KM_NOSLEEP) != 0) {
4820 atomic_inc_64(&cp->cache_alloc_fail);
4821 KMEM_STAT_ADD(kmem_move_stats.kms_constructor_fail);
4822 kmem_slab_free(cp, callback->kmm_to_buf);
4823 kmem_move_end(cp, callback);
4824 return;
4825 }
4826
4827 KMEM_STAT_ADD(kmem_move_stats.kms_callbacks);
4828 KMEM_STAT_COND_ADD((callback->kmm_flags & KMM_NOTIFY),
4829 kmem_move_stats.kms_notify_callbacks);
4830 cp->cache_defrag->kmd_callbacks++;
4831 cp->cache_defrag->kmd_thread = curthread;
4832 cp->cache_defrag->kmd_from_buf = callback->kmm_from_buf;
4833 cp->cache_defrag->kmd_to_buf = callback->kmm_to_buf;
4834 DTRACE_PROBE2(kmem__move__start, kmem_cache_t *, cp, kmem_move_t *,
4835 callback);
4836
4837 response = cp->cache_move(callback->kmm_from_buf,
4838 callback->kmm_to_buf, cp->cache_bufsize, cp->cache_private);
4839
4840 DTRACE_PROBE3(kmem__move__end, kmem_cache_t *, cp, kmem_move_t *,
4841 callback, kmem_cbrc_t, response);
4842 cp->cache_defrag->kmd_thread = NULL;
4843 cp->cache_defrag->kmd_from_buf = NULL;
4844 cp->cache_defrag->kmd_to_buf = NULL;
4845
4846 if (response == KMEM_CBRC_YES) {
4847 KMEM_STAT_ADD(kmem_move_stats.kms_yes);
4848 cp->cache_defrag->kmd_yes++;
4849 kmem_slab_free_constructed(cp, callback->kmm_from_buf, B_FALSE);
4850 /* slab safe to access until kmem_move_end() */
4851 if (sp->slab_refcnt == 0)
4852 cp->cache_defrag->kmd_slabs_freed++;
4853 mutex_enter(&cp->cache_lock);
4854 kmem_slab_move_yes(cp, sp, callback->kmm_from_buf);
4855 mutex_exit(&cp->cache_lock);
4856 kmem_move_end(cp, callback);
4857 return;
4858 }
4859
4860 switch (response) {
4861 case KMEM_CBRC_NO:
4862 KMEM_STAT_ADD(kmem_move_stats.kms_no);
4863 cp->cache_defrag->kmd_no++;
4864 mutex_enter(&cp->cache_lock);
4865 kmem_slab_move_no(cp, sp, callback->kmm_from_buf);
4866 mutex_exit(&cp->cache_lock);
4867 break;
4868 case KMEM_CBRC_LATER:
4869 KMEM_STAT_ADD(kmem_move_stats.kms_later);
4870 cp->cache_defrag->kmd_later++;
4871 mutex_enter(&cp->cache_lock);
4872 if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4873 mutex_exit(&cp->cache_lock);
4874 break;
4875 }
4876
4877 if (++sp->slab_later_count >= KMEM_DISBELIEF) {
4878 KMEM_STAT_ADD(kmem_move_stats.kms_disbelief);
4879 kmem_slab_move_no(cp, sp, callback->kmm_from_buf);
4880 } else if (!(sp->slab_flags & KMEM_SLAB_NOMOVE)) {
4881 sp->slab_stuck_offset = KMEM_SLAB_OFFSET(sp,
4882 callback->kmm_from_buf);
4883 }
4884 mutex_exit(&cp->cache_lock);
4885 break;
4886 case KMEM_CBRC_DONT_NEED:
4887 KMEM_STAT_ADD(kmem_move_stats.kms_dont_need);
4888 cp->cache_defrag->kmd_dont_need++;
4889 kmem_slab_free_constructed(cp, callback->kmm_from_buf, B_FALSE);
4890 if (sp->slab_refcnt == 0)
4891 cp->cache_defrag->kmd_slabs_freed++;
4892 mutex_enter(&cp->cache_lock);
4893 kmem_slab_move_yes(cp, sp, callback->kmm_from_buf);
4894 mutex_exit(&cp->cache_lock);
4895 break;
4896 case KMEM_CBRC_DONT_KNOW:
4897 KMEM_STAT_ADD(kmem_move_stats.kms_dont_know);
4898 cp->cache_defrag->kmd_dont_know++;
4899 if (kmem_hunt_mags(cp, callback->kmm_from_buf) != NULL) {
4900 KMEM_STAT_ADD(kmem_move_stats.kms_hunt_found_mag);
4901 cp->cache_defrag->kmd_hunt_found++;
4902 kmem_slab_free_constructed(cp, callback->kmm_from_buf,
4903 B_TRUE);
4904 if (sp->slab_refcnt == 0)
4905 cp->cache_defrag->kmd_slabs_freed++;
4906 mutex_enter(&cp->cache_lock);
4907 kmem_slab_move_yes(cp, sp, callback->kmm_from_buf);
4908 mutex_exit(&cp->cache_lock);
4909 }
4910 break;
4911 default:
4912 panic("'%s' (%p) unexpected move callback response %d\n",
4913 cp->cache_name, (void *)cp, response);
4914 }
4915
4916 kmem_slab_free_constructed(cp, callback->kmm_to_buf, B_FALSE);
4917 kmem_move_end(cp, callback);
4918 }
4919
4920 /* Return B_FALSE if there is insufficient memory for the move request. */
4921 static boolean_t
kmem_move_begin(kmem_cache_t * cp,kmem_slab_t * sp,void * buf,int flags)4922 kmem_move_begin(kmem_cache_t *cp, kmem_slab_t *sp, void *buf, int flags)
4923 {
4924 void *to_buf;
4925 avl_index_t index;
4926 kmem_move_t *callback, *pending;
4927 ulong_t n;
4928
4929 ASSERT(taskq_member(kmem_taskq, curthread));
4930 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4931 ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
4932
4933 callback = kmem_cache_alloc(kmem_move_cache, KM_NOSLEEP);
4934 if (callback == NULL) {
4935 KMEM_STAT_ADD(kmem_move_stats.kms_callback_alloc_fail);
4936 return (B_FALSE);
4937 }
4938
4939 callback->kmm_from_slab = sp;
4940 callback->kmm_from_buf = buf;
4941 callback->kmm_flags = flags;
4942
4943 mutex_enter(&cp->cache_lock);
4944
4945 n = avl_numnodes(&cp->cache_partial_slabs);
4946 if ((n == 0) || ((n == 1) && !(flags & KMM_DEBUG))) {
4947 mutex_exit(&cp->cache_lock);
4948 kmem_cache_free(kmem_move_cache, callback);
4949 return (B_TRUE); /* there is no need for the move request */
4950 }
4951
4952 pending = avl_find(&cp->cache_defrag->kmd_moves_pending, buf, &index);
4953 if (pending != NULL) {
4954 /*
4955 * If the move is already pending and we're desperate now,
4956 * update the move flags.
4957 */
4958 if (flags & KMM_DESPERATE) {
4959 pending->kmm_flags |= KMM_DESPERATE;
4960 }
4961 mutex_exit(&cp->cache_lock);
4962 KMEM_STAT_ADD(kmem_move_stats.kms_already_pending);
4963 kmem_cache_free(kmem_move_cache, callback);
4964 return (B_TRUE);
4965 }
4966
4967 to_buf = kmem_slab_alloc_impl(cp, avl_first(&cp->cache_partial_slabs),
4968 B_FALSE);
4969 callback->kmm_to_buf = to_buf;
4970 avl_insert(&cp->cache_defrag->kmd_moves_pending, callback, index);
4971
4972 mutex_exit(&cp->cache_lock);
4973
4974 if (!taskq_dispatch(kmem_move_taskq, (task_func_t *)kmem_move_buffer,
4975 callback, TQ_NOSLEEP)) {
4976 KMEM_STAT_ADD(kmem_move_stats.kms_callback_taskq_fail);
4977 mutex_enter(&cp->cache_lock);
4978 avl_remove(&cp->cache_defrag->kmd_moves_pending, callback);
4979 mutex_exit(&cp->cache_lock);
4980 kmem_slab_free(cp, to_buf);
4981 kmem_cache_free(kmem_move_cache, callback);
4982 return (B_FALSE);
4983 }
4984
4985 return (B_TRUE);
4986 }
4987
4988 static void
kmem_move_end(kmem_cache_t * cp,kmem_move_t * callback)4989 kmem_move_end(kmem_cache_t *cp, kmem_move_t *callback)
4990 {
4991 avl_index_t index;
4992
4993 ASSERT(cp->cache_defrag != NULL);
4994 ASSERT(taskq_member(kmem_move_taskq, curthread));
4995 ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4996
4997 mutex_enter(&cp->cache_lock);
4998 VERIFY(avl_find(&cp->cache_defrag->kmd_moves_pending,
4999 callback->kmm_from_buf, &index) != NULL);
5000 avl_remove(&cp->cache_defrag->kmd_moves_pending, callback);
5001 if (avl_is_empty(&cp->cache_defrag->kmd_moves_pending)) {
5002 list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
5003 kmem_slab_t *sp;
5004
5005 /*
5006 * The last pending move completed. Release all slabs from the
5007 * front of the dead list except for any slab at the tail that
5008 * needs to be released from the context of kmem_move_buffers().
5009 * kmem deferred unmapping the buffers on these slabs in order
5010 * to guarantee that buffers passed to the move callback have
5011 * been touched only by kmem or by the client itself.
5012 */
5013 while ((sp = list_remove_head(deadlist)) != NULL) {
5014 if (sp->slab_flags & KMEM_SLAB_MOVE_PENDING) {
5015 list_insert_tail(deadlist, sp);
5016 break;
5017 }
5018 cp->cache_defrag->kmd_deadcount--;
5019 cp->cache_slab_destroy++;
5020 mutex_exit(&cp->cache_lock);
5021 kmem_slab_destroy(cp, sp);
5022 KMEM_STAT_ADD(kmem_move_stats.kms_dead_slabs_freed);
5023 mutex_enter(&cp->cache_lock);
5024 }
5025 }
5026 mutex_exit(&cp->cache_lock);
5027 kmem_cache_free(kmem_move_cache, callback);
5028 }
5029
5030 /*
5031 * Move buffers from least used slabs first by scanning backwards from the end
5032 * of the partial slab list. Scan at most max_scan candidate slabs and move
5033 * buffers from at most max_slabs slabs (0 for all partial slabs in both cases).
5034 * If desperate to reclaim memory, move buffers from any partial slab, otherwise
5035 * skip slabs with a ratio of allocated buffers at or above the current
5036 * threshold. Return the number of unskipped slabs (at most max_slabs, -1 if the
5037 * scan is aborted) so that the caller can adjust the reclaimability threshold
5038 * depending on how many reclaimable slabs it finds.
5039 *
5040 * kmem_move_buffers() drops and reacquires cache_lock every time it issues a
5041 * move request, since it is not valid for kmem_move_begin() to call
5042 * kmem_cache_alloc() or taskq_dispatch() with cache_lock held.
5043 */
5044 static int
kmem_move_buffers(kmem_cache_t * cp,size_t max_scan,size_t max_slabs,int flags)5045 kmem_move_buffers(kmem_cache_t *cp, size_t max_scan, size_t max_slabs,
5046 int flags)
5047 {
5048 kmem_slab_t *sp;
5049 void *buf;
5050 int i, j; /* slab index, buffer index */
5051 int s; /* reclaimable slabs */
5052 int b; /* allocated (movable) buffers on reclaimable slab */
5053 boolean_t success;
5054 int refcnt;
5055 int nomove;
5056
5057 ASSERT(taskq_member(kmem_taskq, curthread));
5058 ASSERT(MUTEX_HELD(&cp->cache_lock));
5059 ASSERT(kmem_move_cache != NULL);
5060 ASSERT(cp->cache_move != NULL && cp->cache_defrag != NULL);
5061 ASSERT((flags & KMM_DEBUG) ? !avl_is_empty(&cp->cache_partial_slabs) :
5062 avl_numnodes(&cp->cache_partial_slabs) > 1);
5063
5064 if (kmem_move_blocked) {
5065 return (0);
5066 }
5067
5068 if (kmem_move_fulltilt) {
5069 flags |= KMM_DESPERATE;
5070 }
5071
5072 if (max_scan == 0 || (flags & KMM_DESPERATE)) {
5073 /*
5074 * Scan as many slabs as needed to find the desired number of
5075 * candidate slabs.
5076 */
5077 max_scan = (size_t)-1;
5078 }
5079
5080 if (max_slabs == 0 || (flags & KMM_DESPERATE)) {
5081 /* Find as many candidate slabs as possible. */
5082 max_slabs = (size_t)-1;
5083 }
5084
5085 sp = avl_last(&cp->cache_partial_slabs);
5086 ASSERT(KMEM_SLAB_IS_PARTIAL(sp));
5087 for (i = 0, s = 0; (i < max_scan) && (s < max_slabs) && (sp != NULL) &&
5088 ((sp != avl_first(&cp->cache_partial_slabs)) ||
5089 (flags & KMM_DEBUG));
5090 sp = AVL_PREV(&cp->cache_partial_slabs, sp), i++) {
5091
5092 if (!kmem_slab_is_reclaimable(cp, sp, flags)) {
5093 continue;
5094 }
5095 s++;
5096
5097 /* Look for allocated buffers to move. */
5098 for (j = 0, b = 0, buf = sp->slab_base;
5099 (j < sp->slab_chunks) && (b < sp->slab_refcnt);
5100 buf = (((char *)buf) + cp->cache_chunksize), j++) {
5101
5102 if (kmem_slab_allocated(cp, sp, buf) == NULL) {
5103 continue;
5104 }
5105
5106 b++;
5107
5108 /*
5109 * Prevent the slab from being destroyed while we drop
5110 * cache_lock and while the pending move is not yet
5111 * registered. Flag the pending move while
5112 * kmd_moves_pending may still be empty, since we can't
5113 * yet rely on a non-zero pending move count to prevent
5114 * the slab from being destroyed.
5115 */
5116 ASSERT(!(sp->slab_flags & KMEM_SLAB_MOVE_PENDING));
5117 sp->slab_flags |= KMEM_SLAB_MOVE_PENDING;
5118 /*
5119 * Recheck refcnt and nomove after reacquiring the lock,
5120 * since these control the order of partial slabs, and
5121 * we want to know if we can pick up the scan where we
5122 * left off.
5123 */
5124 refcnt = sp->slab_refcnt;
5125 nomove = (sp->slab_flags & KMEM_SLAB_NOMOVE);
5126 mutex_exit(&cp->cache_lock);
5127
5128 success = kmem_move_begin(cp, sp, buf, flags);
5129
5130 /*
5131 * Now, before the lock is reacquired, kmem could
5132 * process all pending move requests and purge the
5133 * deadlist, so that upon reacquiring the lock, sp has
5134 * been remapped. Or, the client may free all the
5135 * objects on the slab while the pending moves are still
5136 * on the taskq. Therefore, the KMEM_SLAB_MOVE_PENDING
5137 * flag causes the slab to be put at the end of the
5138 * deadlist and prevents it from being destroyed, since
5139 * we plan to destroy it here after reacquiring the
5140 * lock.
5141 */
5142 mutex_enter(&cp->cache_lock);
5143 ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
5144 sp->slab_flags &= ~KMEM_SLAB_MOVE_PENDING;
5145
5146 if (sp->slab_refcnt == 0) {
5147 list_t *deadlist =
5148 &cp->cache_defrag->kmd_deadlist;
5149 list_remove(deadlist, sp);
5150
5151 if (!avl_is_empty(
5152 &cp->cache_defrag->kmd_moves_pending)) {
5153 /*
5154 * A pending move makes it unsafe to
5155 * destroy the slab, because even though
5156 * the move is no longer needed, the
5157 * context where that is determined
5158 * requires the slab to exist.
5159 * Fortunately, a pending move also
5160 * means we don't need to destroy the
5161 * slab here, since it will get
5162 * destroyed along with any other slabs
5163 * on the deadlist after the last
5164 * pending move completes.
5165 */
5166 list_insert_head(deadlist, sp);
5167 KMEM_STAT_ADD(kmem_move_stats.
5168 kms_endscan_slab_dead);
5169 return (-1);
5170 }
5171
5172 /*
5173 * Destroy the slab now if it was completely
5174 * freed while we dropped cache_lock and there
5175 * are no pending moves. Since slab_refcnt
5176 * cannot change once it reaches zero, no new
5177 * pending moves from that slab are possible.
5178 */
5179 cp->cache_defrag->kmd_deadcount--;
5180 cp->cache_slab_destroy++;
5181 mutex_exit(&cp->cache_lock);
5182 kmem_slab_destroy(cp, sp);
5183 KMEM_STAT_ADD(kmem_move_stats.
5184 kms_dead_slabs_freed);
5185 KMEM_STAT_ADD(kmem_move_stats.
5186 kms_endscan_slab_destroyed);
5187 mutex_enter(&cp->cache_lock);
5188 /*
5189 * Since we can't pick up the scan where we left
5190 * off, abort the scan and say nothing about the
5191 * number of reclaimable slabs.
5192 */
5193 return (-1);
5194 }
5195
5196 if (!success) {
5197 /*
5198 * Abort the scan if there is not enough memory
5199 * for the request and say nothing about the
5200 * number of reclaimable slabs.
5201 */
5202 KMEM_STAT_COND_ADD(s < max_slabs,
5203 kmem_move_stats.kms_endscan_nomem);
5204 return (-1);
5205 }
5206
5207 /*
5208 * The slab's position changed while the lock was
5209 * dropped, so we don't know where we are in the
5210 * sequence any more.
5211 */
5212 if (sp->slab_refcnt != refcnt) {
5213 /*
5214 * If this is a KMM_DEBUG move, the slab_refcnt
5215 * may have changed because we allocated a
5216 * destination buffer on the same slab. In that
5217 * case, we're not interested in counting it.
5218 */
5219 KMEM_STAT_COND_ADD(!(flags & KMM_DEBUG) &&
5220 (s < max_slabs),
5221 kmem_move_stats.kms_endscan_refcnt_changed);
5222 return (-1);
5223 }
5224 if ((sp->slab_flags & KMEM_SLAB_NOMOVE) != nomove) {
5225 KMEM_STAT_COND_ADD(s < max_slabs,
5226 kmem_move_stats.kms_endscan_nomove_changed);
5227 return (-1);
5228 }
5229
5230 /*
5231 * Generating a move request allocates a destination
5232 * buffer from the slab layer, bumping the first partial
5233 * slab if it is completely allocated. If the current
5234 * slab becomes the first partial slab as a result, we
5235 * can't continue to scan backwards.
5236 *
5237 * If this is a KMM_DEBUG move and we allocated the
5238 * destination buffer from the last partial slab, then
5239 * the buffer we're moving is on the same slab and our
5240 * slab_refcnt has changed, causing us to return before
5241 * reaching here if there are no partial slabs left.
5242 */
5243 ASSERT(!avl_is_empty(&cp->cache_partial_slabs));
5244 if (sp == avl_first(&cp->cache_partial_slabs)) {
5245 /*
5246 * We're not interested in a second KMM_DEBUG
5247 * move.
5248 */
5249 goto end_scan;
5250 }
5251 }
5252 }
5253 end_scan:
5254
5255 KMEM_STAT_COND_ADD(!(flags & KMM_DEBUG) &&
5256 (s < max_slabs) &&
5257 (sp == avl_first(&cp->cache_partial_slabs)),
5258 kmem_move_stats.kms_endscan_freelist);
5259
5260 return (s);
5261 }
5262
5263 typedef struct kmem_move_notify_args {
5264 kmem_cache_t *kmna_cache;
5265 void *kmna_buf;
5266 } kmem_move_notify_args_t;
5267
5268 static void
kmem_cache_move_notify_task(void * arg)5269 kmem_cache_move_notify_task(void *arg)
5270 {
5271 kmem_move_notify_args_t *args = arg;
5272 kmem_cache_t *cp = args->kmna_cache;
5273 void *buf = args->kmna_buf;
5274 kmem_slab_t *sp;
5275
5276 ASSERT(taskq_member(kmem_taskq, curthread));
5277 ASSERT(list_link_active(&cp->cache_link));
5278
5279 kmem_free(args, sizeof (kmem_move_notify_args_t));
5280 mutex_enter(&cp->cache_lock);
5281 sp = kmem_slab_allocated(cp, NULL, buf);
5282
5283 /* Ignore the notification if the buffer is no longer allocated. */
5284 if (sp == NULL) {
5285 mutex_exit(&cp->cache_lock);
5286 return;
5287 }
5288
5289 /* Ignore the notification if there's no reason to move the buffer. */
5290 if (avl_numnodes(&cp->cache_partial_slabs) > 1) {
5291 /*
5292 * So far the notification is not ignored. Ignore the
5293 * notification if the slab is not marked by an earlier refusal
5294 * to move a buffer.
5295 */
5296 if (!(sp->slab_flags & KMEM_SLAB_NOMOVE) &&
5297 (sp->slab_later_count == 0)) {
5298 mutex_exit(&cp->cache_lock);
5299 return;
5300 }
5301
5302 kmem_slab_move_yes(cp, sp, buf);
5303 ASSERT(!(sp->slab_flags & KMEM_SLAB_MOVE_PENDING));
5304 sp->slab_flags |= KMEM_SLAB_MOVE_PENDING;
5305 mutex_exit(&cp->cache_lock);
5306 /* see kmem_move_buffers() about dropping the lock */
5307 (void) kmem_move_begin(cp, sp, buf, KMM_NOTIFY);
5308 mutex_enter(&cp->cache_lock);
5309 ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
5310 sp->slab_flags &= ~KMEM_SLAB_MOVE_PENDING;
5311 if (sp->slab_refcnt == 0) {
5312 list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
5313 list_remove(deadlist, sp);
5314
5315 if (!avl_is_empty(
5316 &cp->cache_defrag->kmd_moves_pending)) {
5317 list_insert_head(deadlist, sp);
5318 mutex_exit(&cp->cache_lock);
5319 KMEM_STAT_ADD(kmem_move_stats.
5320 kms_notify_slab_dead);
5321 return;
5322 }
5323
5324 cp->cache_defrag->kmd_deadcount--;
5325 cp->cache_slab_destroy++;
5326 mutex_exit(&cp->cache_lock);
5327 kmem_slab_destroy(cp, sp);
5328 KMEM_STAT_ADD(kmem_move_stats.kms_dead_slabs_freed);
5329 KMEM_STAT_ADD(kmem_move_stats.
5330 kms_notify_slab_destroyed);
5331 return;
5332 }
5333 } else {
5334 kmem_slab_move_yes(cp, sp, buf);
5335 }
5336 mutex_exit(&cp->cache_lock);
5337 }
5338
5339 void
kmem_cache_move_notify(kmem_cache_t * cp,void * buf)5340 kmem_cache_move_notify(kmem_cache_t *cp, void *buf)
5341 {
5342 kmem_move_notify_args_t *args;
5343
5344 KMEM_STAT_ADD(kmem_move_stats.kms_notify);
5345 args = kmem_alloc(sizeof (kmem_move_notify_args_t), KM_NOSLEEP);
5346 if (args != NULL) {
5347 args->kmna_cache = cp;
5348 args->kmna_buf = buf;
5349 if (!taskq_dispatch(kmem_taskq,
5350 (task_func_t *)kmem_cache_move_notify_task, args,
5351 TQ_NOSLEEP))
5352 kmem_free(args, sizeof (kmem_move_notify_args_t));
5353 }
5354 }
5355
5356 static void
kmem_cache_defrag(kmem_cache_t * cp)5357 kmem_cache_defrag(kmem_cache_t *cp)
5358 {
5359 size_t n;
5360
5361 ASSERT(cp->cache_defrag != NULL);
5362
5363 mutex_enter(&cp->cache_lock);
5364 n = avl_numnodes(&cp->cache_partial_slabs);
5365 if (n > 1) {
5366 /* kmem_move_buffers() drops and reacquires cache_lock */
5367 KMEM_STAT_ADD(kmem_move_stats.kms_defrags);
5368 cp->cache_defrag->kmd_defrags++;
5369 (void) kmem_move_buffers(cp, n, 0, KMM_DESPERATE);
5370 }
5371 mutex_exit(&cp->cache_lock);
5372 }
5373
5374 /* Is this cache above the fragmentation threshold? */
5375 static boolean_t
kmem_cache_frag_threshold(kmem_cache_t * cp,uint64_t nfree)5376 kmem_cache_frag_threshold(kmem_cache_t *cp, uint64_t nfree)
5377 {
5378 /*
5379 * nfree kmem_frag_numer
5380 * ------------------ > ---------------
5381 * cp->cache_buftotal kmem_frag_denom
5382 */
5383 return ((nfree * kmem_frag_denom) >
5384 (cp->cache_buftotal * kmem_frag_numer));
5385 }
5386
5387 static boolean_t
kmem_cache_is_fragmented(kmem_cache_t * cp,boolean_t * doreap)5388 kmem_cache_is_fragmented(kmem_cache_t *cp, boolean_t *doreap)
5389 {
5390 boolean_t fragmented;
5391 uint64_t nfree;
5392
5393 ASSERT(MUTEX_HELD(&cp->cache_lock));
5394 *doreap = B_FALSE;
5395
5396 if (kmem_move_fulltilt) {
5397 if (avl_numnodes(&cp->cache_partial_slabs) > 1) {
5398 return (B_TRUE);
5399 }
5400 } else {
5401 if ((cp->cache_complete_slab_count + avl_numnodes(
5402 &cp->cache_partial_slabs)) < kmem_frag_minslabs) {
5403 return (B_FALSE);
5404 }
5405 }
5406
5407 nfree = cp->cache_bufslab;
5408 fragmented = ((avl_numnodes(&cp->cache_partial_slabs) > 1) &&
5409 kmem_cache_frag_threshold(cp, nfree));
5410
5411 /*
5412 * Free buffers in the magazine layer appear allocated from the point of
5413 * view of the slab layer. We want to know if the slab layer would
5414 * appear fragmented if we included free buffers from magazines that
5415 * have fallen out of the working set.
5416 */
5417 if (!fragmented) {
5418 long reap;
5419
5420 mutex_enter(&cp->cache_depot_lock);
5421 reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
5422 reap = MIN(reap, cp->cache_full.ml_total);
5423 mutex_exit(&cp->cache_depot_lock);
5424
5425 nfree += ((uint64_t)reap * cp->cache_magtype->mt_magsize);
5426 if (kmem_cache_frag_threshold(cp, nfree)) {
5427 *doreap = B_TRUE;
5428 }
5429 }
5430
5431 return (fragmented);
5432 }
5433
5434 /* Called periodically from kmem_taskq */
5435 static void
kmem_cache_scan(kmem_cache_t * cp)5436 kmem_cache_scan(kmem_cache_t *cp)
5437 {
5438 boolean_t reap = B_FALSE;
5439 kmem_defrag_t *kmd;
5440
5441 ASSERT(taskq_member(kmem_taskq, curthread));
5442
5443 mutex_enter(&cp->cache_lock);
5444
5445 kmd = cp->cache_defrag;
5446 if (kmd->kmd_consolidate > 0) {
5447 kmd->kmd_consolidate--;
5448 mutex_exit(&cp->cache_lock);
5449 kmem_cache_reap(cp);
5450 return;
5451 }
5452
5453 if (kmem_cache_is_fragmented(cp, &reap)) {
5454 size_t slabs_found;
5455
5456 /*
5457 * Consolidate reclaimable slabs from the end of the partial
5458 * slab list (scan at most kmem_reclaim_scan_range slabs to find
5459 * reclaimable slabs). Keep track of how many candidate slabs we
5460 * looked for and how many we actually found so we can adjust
5461 * the definition of a candidate slab if we're having trouble
5462 * finding them.
5463 *
5464 * kmem_move_buffers() drops and reacquires cache_lock.
5465 */
5466 KMEM_STAT_ADD(kmem_move_stats.kms_scans);
5467 kmd->kmd_scans++;
5468 slabs_found = kmem_move_buffers(cp, kmem_reclaim_scan_range,
5469 kmem_reclaim_max_slabs, 0);
5470 if (slabs_found >= 0) {
5471 kmd->kmd_slabs_sought += kmem_reclaim_max_slabs;
5472 kmd->kmd_slabs_found += slabs_found;
5473 }
5474
5475 if (++kmd->kmd_tries >= kmem_reclaim_scan_range) {
5476 kmd->kmd_tries = 0;
5477
5478 /*
5479 * If we had difficulty finding candidate slabs in
5480 * previous scans, adjust the threshold so that
5481 * candidates are easier to find.
5482 */
5483 if (kmd->kmd_slabs_found == kmd->kmd_slabs_sought) {
5484 kmem_adjust_reclaim_threshold(kmd, -1);
5485 } else if ((kmd->kmd_slabs_found * 2) <
5486 kmd->kmd_slabs_sought) {
5487 kmem_adjust_reclaim_threshold(kmd, 1);
5488 }
5489 kmd->kmd_slabs_sought = 0;
5490 kmd->kmd_slabs_found = 0;
5491 }
5492 } else {
5493 kmem_reset_reclaim_threshold(cp->cache_defrag);
5494 #ifdef DEBUG
5495 if (!avl_is_empty(&cp->cache_partial_slabs)) {
5496 /*
5497 * In a debug kernel we want the consolidator to
5498 * run occasionally even when there is plenty of
5499 * memory.
5500 */
5501 uint16_t debug_rand;
5502
5503 (void) random_get_bytes((uint8_t *)&debug_rand, 2);
5504 if (!kmem_move_noreap &&
5505 ((debug_rand % kmem_mtb_reap) == 0)) {
5506 mutex_exit(&cp->cache_lock);
5507 KMEM_STAT_ADD(kmem_move_stats.kms_debug_reaps);
5508 kmem_cache_reap(cp);
5509 return;
5510 } else if ((debug_rand % kmem_mtb_move) == 0) {
5511 KMEM_STAT_ADD(kmem_move_stats.kms_scans);
5512 KMEM_STAT_ADD(kmem_move_stats.kms_debug_scans);
5513 kmd->kmd_scans++;
5514 (void) kmem_move_buffers(cp,
5515 kmem_reclaim_scan_range, 1, KMM_DEBUG);
5516 }
5517 }
5518 #endif /* DEBUG */
5519 }
5520
5521 mutex_exit(&cp->cache_lock);
5522
5523 if (reap) {
5524 KMEM_STAT_ADD(kmem_move_stats.kms_scan_depot_ws_reaps);
5525 kmem_depot_ws_reap(cp);
5526 }
5527 }
5528