xref: /illumos-gate/usr/src/uts/common/os/kmem.c (revision baf00aa8)
1 /*
2  * CDDL HEADER START
3  *
4  * The contents of this file are subject to the terms of the
5  * Common Development and Distribution License (the "License").
6  * You may not use this file except in compliance with the License.
7  *
8  * You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
9  * or http://www.opensolaris.org/os/licensing.
10  * See the License for the specific language governing permissions
11  * and limitations under the License.
12  *
13  * When distributing Covered Code, include this CDDL HEADER in each
14  * file and include the License file at usr/src/OPENSOLARIS.LICENSE.
15  * If applicable, add the following below this CDDL HEADER, with the
16  * fields enclosed by brackets "[]" replaced with your own identifying
17  * information: Portions Copyright [yyyy] [name of copyright owner]
18  *
19  * CDDL HEADER END
20  */
21 /*
22  * Copyright (c) 1994, 2010, Oracle and/or its affiliates. All rights reserved.
23  * Copyright (c) 2012, 2017 by Delphix. All rights reserved.
24  * Copyright 2015 Nexenta Systems, Inc.  All rights reserved.
25  * Copyright 2018, Joyent, Inc.
26  * Copyright 2020 Oxide Computer Company
27  */
28 
29 /*
30  * Kernel memory allocator, as described in the following two papers and a
31  * statement about the consolidator:
32  *
33  * Jeff Bonwick,
34  * The Slab Allocator: An Object-Caching Kernel Memory Allocator.
35  * Proceedings of the Summer 1994 Usenix Conference.
36  * Available as /shared/sac/PSARC/1994/028/materials/kmem.pdf.
37  *
38  * Jeff Bonwick and Jonathan Adams,
39  * Magazines and vmem: Extending the Slab Allocator to Many CPUs and
40  * Arbitrary Resources.
41  * Proceedings of the 2001 Usenix Conference.
42  * Available as /shared/sac/PSARC/2000/550/materials/vmem.pdf.
43  *
44  * kmem Slab Consolidator Big Theory Statement:
45  *
46  * 1. Motivation
47  *
48  * As stated in Bonwick94, slabs provide the following advantages over other
49  * allocation structures in terms of memory fragmentation:
50  *
51  *  - Internal fragmentation (per-buffer wasted space) is minimal.
52  *  - Severe external fragmentation (unused buffers on the free list) is
53  *    unlikely.
54  *
55  * Segregating objects by size eliminates one source of external fragmentation,
56  * and according to Bonwick:
57  *
58  *   The other reason that slabs reduce external fragmentation is that all
59  *   objects in a slab are of the same type, so they have the same lifetime
60  *   distribution. The resulting segregation of short-lived and long-lived
61  *   objects at slab granularity reduces the likelihood of an entire page being
62  *   held hostage due to a single long-lived allocation [Barrett93, Hanson90].
63  *
64  * While unlikely, severe external fragmentation remains possible. Clients that
65  * allocate both short- and long-lived objects from the same cache cannot
66  * anticipate the distribution of long-lived objects within the allocator's slab
67  * implementation. Even a small percentage of long-lived objects distributed
68  * randomly across many slabs can lead to a worst case scenario where the client
69  * frees the majority of its objects and the system gets back almost none of the
70  * slabs. Despite the client doing what it reasonably can to help the system
71  * reclaim memory, the allocator cannot shake free enough slabs because of
72  * lonely allocations stubbornly hanging on. Although the allocator is in a
73  * position to diagnose the fragmentation, there is nothing that the allocator
74  * by itself can do about it. It only takes a single allocated object to prevent
75  * an entire slab from being reclaimed, and any object handed out by
76  * kmem_cache_alloc() is by definition in the client's control. Conversely,
77  * although the client is in a position to move a long-lived object, it has no
78  * way of knowing if the object is causing fragmentation, and if so, where to
79  * move it. A solution necessarily requires further cooperation between the
80  * allocator and the client.
81  *
82  * 2. Move Callback
83  *
84  * The kmem slab consolidator therefore adds a move callback to the
85  * allocator/client interface, improving worst-case external fragmentation in
86  * kmem caches that supply a function to move objects from one memory location
87  * to another. In a situation of low memory kmem attempts to consolidate all of
88  * a cache's slabs at once; otherwise it works slowly to bring external
89  * fragmentation within the 1/8 limit guaranteed for internal fragmentation,
90  * thereby helping to avoid a low memory situation in the future.
91  *
92  * The callback has the following signature:
93  *
94  *   kmem_cbrc_t move(void *old, void *new, size_t size, void *user_arg)
95  *
96  * It supplies the kmem client with two addresses: the allocated object that
97  * kmem wants to move and a buffer selected by kmem for the client to use as the
98  * copy destination. The callback is kmem's way of saying "Please get off of
99  * this buffer and use this one instead." kmem knows where it wants to move the
100  * object in order to best reduce fragmentation. All the client needs to know
101  * about the second argument (void *new) is that it is an allocated, constructed
102  * object ready to take the contents of the old object. When the move function
103  * is called, the system is likely to be low on memory, and the new object
104  * spares the client from having to worry about allocating memory for the
105  * requested move. The third argument supplies the size of the object, in case a
106  * single move function handles multiple caches whose objects differ only in
107  * size (such as zio_buf_512, zio_buf_1024, etc). Finally, the same optional
108  * user argument passed to the constructor, destructor, and reclaim functions is
109  * also passed to the move callback.
110  *
111  * 2.1 Setting the Move Callback
112  *
113  * The client sets the move callback after creating the cache and before
114  * allocating from it:
115  *
116  *	object_cache = kmem_cache_create(...);
117  *      kmem_cache_set_move(object_cache, object_move);
118  *
119  * 2.2 Move Callback Return Values
120  *
121  * Only the client knows about its own data and when is a good time to move it.
122  * The client is cooperating with kmem to return unused memory to the system,
123  * and kmem respectfully accepts this help at the client's convenience. When
124  * asked to move an object, the client can respond with any of the following:
125  *
126  *   typedef enum kmem_cbrc {
127  *           KMEM_CBRC_YES,
128  *           KMEM_CBRC_NO,
129  *           KMEM_CBRC_LATER,
130  *           KMEM_CBRC_DONT_NEED,
131  *           KMEM_CBRC_DONT_KNOW
132  *   } kmem_cbrc_t;
133  *
134  * The client must not explicitly kmem_cache_free() either of the objects passed
135  * to the callback, since kmem wants to free them directly to the slab layer
136  * (bypassing the per-CPU magazine layer). The response tells kmem which of the
137  * objects to free:
138  *
139  *       YES: (Did it) The client moved the object, so kmem frees the old one.
140  *        NO: (Never) The client refused, so kmem frees the new object (the
141  *            unused copy destination). kmem also marks the slab of the old
142  *            object so as not to bother the client with further callbacks for
143  *            that object as long as the slab remains on the partial slab list.
144  *            (The system won't be getting the slab back as long as the
145  *            immovable object holds it hostage, so there's no point in moving
146  *            any of its objects.)
147  *     LATER: The client is using the object and cannot move it now, so kmem
148  *            frees the new object (the unused copy destination). kmem still
149  *            attempts to move other objects off the slab, since it expects to
150  *            succeed in clearing the slab in a later callback. The client
151  *            should use LATER instead of NO if the object is likely to become
152  *            movable very soon.
153  * DONT_NEED: The client no longer needs the object, so kmem frees the old along
154  *            with the new object (the unused copy destination). This response
155  *            is the client's opportunity to be a model citizen and give back as
156  *            much as it can.
157  * DONT_KNOW: The client does not know about the object because
158  *            a) the client has just allocated the object and not yet put it
159  *               wherever it expects to find known objects
160  *            b) the client has removed the object from wherever it expects to
161  *               find known objects and is about to free it, or
162  *            c) the client has freed the object.
163  *            In all these cases (a, b, and c) kmem frees the new object (the
164  *            unused copy destination).  In the first case, the object is in
165  *            use and the correct action is that for LATER; in the latter two
166  *            cases, we know that the object is either freed or about to be
167  *            freed, in which case it is either already in a magazine or about
168  *            to be in one.  In these cases, we know that the object will either
169  *            be reallocated and reused, or it will end up in a full magazine
170  *            that will be reaped (thereby liberating the slab).  Because it
171  *            is prohibitively expensive to differentiate these cases, and
172  *            because the defrag code is executed when we're low on memory
173  *            (thereby biasing the system to reclaim full magazines) we treat
174  *            all DONT_KNOW cases as LATER and rely on cache reaping to
175  *            generally clean up full magazines.  While we take the same action
176  *            for these cases, we maintain their semantic distinction:  if
177  *            defragmentation is not occurring, it is useful to know if this
178  *            is due to objects in use (LATER) or objects in an unknown state
179  *            of transition (DONT_KNOW).
180  *
181  * 2.3 Object States
182  *
183  * Neither kmem nor the client can be assumed to know the object's whereabouts
184  * at the time of the callback. An object belonging to a kmem cache may be in
185  * any of the following states:
186  *
187  * 1. Uninitialized on the slab
188  * 2. Allocated from the slab but not constructed (still uninitialized)
189  * 3. Allocated from the slab, constructed, but not yet ready for business
190  *    (not in a valid state for the move callback)
191  * 4. In use (valid and known to the client)
192  * 5. About to be freed (no longer in a valid state for the move callback)
193  * 6. Freed to a magazine (still constructed)
194  * 7. Allocated from a magazine, not yet ready for business (not in a valid
195  *    state for the move callback), and about to return to state #4
196  * 8. Deconstructed on a magazine that is about to be freed
197  * 9. Freed to the slab
198  *
199  * Since the move callback may be called at any time while the object is in any
200  * of the above states (except state #1), the client needs a safe way to
201  * determine whether or not it knows about the object. Specifically, the client
202  * needs to know whether or not the object is in state #4, the only state in
203  * which a move is valid. If the object is in any other state, the client should
204  * immediately return KMEM_CBRC_DONT_KNOW, since it is unsafe to access any of
205  * the object's fields.
206  *
207  * Note that although an object may be in state #4 when kmem initiates the move
208  * request, the object may no longer be in that state by the time kmem actually
209  * calls the move function. Not only does the client free objects
210  * asynchronously, kmem itself puts move requests on a queue where thay are
211  * pending until kmem processes them from another context. Also, objects freed
212  * to a magazine appear allocated from the point of view of the slab layer, so
213  * kmem may even initiate requests for objects in a state other than state #4.
214  *
215  * 2.3.1 Magazine Layer
216  *
217  * An important insight revealed by the states listed above is that the magazine
218  * layer is populated only by kmem_cache_free(). Magazines of constructed
219  * objects are never populated directly from the slab layer (which contains raw,
220  * unconstructed objects). Whenever an allocation request cannot be satisfied
221  * from the magazine layer, the magazines are bypassed and the request is
222  * satisfied from the slab layer (creating a new slab if necessary). kmem calls
223  * the object constructor only when allocating from the slab layer, and only in
224  * response to kmem_cache_alloc() or to prepare the destination buffer passed in
225  * the move callback. kmem does not preconstruct objects in anticipation of
226  * kmem_cache_alloc().
227  *
228  * 2.3.2 Object Constructor and Destructor
229  *
230  * If the client supplies a destructor, it must be valid to call the destructor
231  * on a newly created object (immediately after the constructor).
232  *
233  * 2.4 Recognizing Known Objects
234  *
235  * There is a simple test to determine safely whether or not the client knows
236  * about a given object in the move callback. It relies on the fact that kmem
237  * guarantees that the object of the move callback has only been touched by the
238  * client itself or else by kmem. kmem does this by ensuring that none of the
239  * cache's slabs are freed to the virtual memory (VM) subsystem while a move
240  * callback is pending. When the last object on a slab is freed, if there is a
241  * pending move, kmem puts the slab on a per-cache dead list and defers freeing
242  * slabs on that list until all pending callbacks are completed. That way,
243  * clients can be certain that the object of a move callback is in one of the
244  * states listed above, making it possible to distinguish known objects (in
245  * state #4) using the two low order bits of any pointer member (with the
246  * exception of 'char *' or 'short *' which may not be 4-byte aligned on some
247  * platforms).
248  *
249  * The test works as long as the client always transitions objects from state #4
250  * (known, in use) to state #5 (about to be freed, invalid) by setting the low
251  * order bit of the client-designated pointer member. Since kmem only writes
252  * invalid memory patterns, such as 0xbaddcafe to uninitialized memory and
253  * 0xdeadbeef to freed memory, any scribbling on the object done by kmem is
254  * guaranteed to set at least one of the two low order bits. Therefore, given an
255  * object with a back pointer to a 'container_t *o_container', the client can
256  * test
257  *
258  *      container_t *container = object->o_container;
259  *      if ((uintptr_t)container & 0x3) {
260  *              return (KMEM_CBRC_DONT_KNOW);
261  *      }
262  *
263  * Typically, an object will have a pointer to some structure with a list or
264  * hash where objects from the cache are kept while in use. Assuming that the
265  * client has some way of knowing that the container structure is valid and will
266  * not go away during the move, and assuming that the structure includes a lock
267  * to protect whatever collection is used, then the client would continue as
268  * follows:
269  *
270  *	// Ensure that the container structure does not go away.
271  *      if (container_hold(container) == 0) {
272  *              return (KMEM_CBRC_DONT_KNOW);
273  *      }
274  *      mutex_enter(&container->c_objects_lock);
275  *      if (container != object->o_container) {
276  *              mutex_exit(&container->c_objects_lock);
277  *              container_rele(container);
278  *              return (KMEM_CBRC_DONT_KNOW);
279  *      }
280  *
281  * At this point the client knows that the object cannot be freed as long as
282  * c_objects_lock is held. Note that after acquiring the lock, the client must
283  * recheck the o_container pointer in case the object was removed just before
284  * acquiring the lock.
285  *
286  * When the client is about to free an object, it must first remove that object
287  * from the list, hash, or other structure where it is kept. At that time, to
288  * mark the object so it can be distinguished from the remaining, known objects,
289  * the client sets the designated low order bit:
290  *
291  *      mutex_enter(&container->c_objects_lock);
292  *      object->o_container = (void *)((uintptr_t)object->o_container | 0x1);
293  *      list_remove(&container->c_objects, object);
294  *      mutex_exit(&container->c_objects_lock);
295  *
296  * In the common case, the object is freed to the magazine layer, where it may
297  * be reused on a subsequent allocation without the overhead of calling the
298  * constructor. While in the magazine it appears allocated from the point of
299  * view of the slab layer, making it a candidate for the move callback. Most
300  * objects unrecognized by the client in the move callback fall into this
301  * category and are cheaply distinguished from known objects by the test
302  * described earlier. Because searching magazines is prohibitively expensive
303  * for kmem, clients that do not mark freed objects (and therefore return
304  * KMEM_CBRC_DONT_KNOW for large numbers of objects) may find defragmentation
305  * efficacy reduced.
306  *
307  * Invalidating the designated pointer member before freeing the object marks
308  * the object to be avoided in the callback, and conversely, assigning a valid
309  * value to the designated pointer member after allocating the object makes the
310  * object fair game for the callback:
311  *
312  *      ... allocate object ...
313  *      ... set any initial state not set by the constructor ...
314  *
315  *      mutex_enter(&container->c_objects_lock);
316  *      list_insert_tail(&container->c_objects, object);
317  *      membar_producer();
318  *      object->o_container = container;
319  *      mutex_exit(&container->c_objects_lock);
320  *
321  * Note that everything else must be valid before setting o_container makes the
322  * object fair game for the move callback. The membar_producer() call ensures
323  * that all the object's state is written to memory before setting the pointer
324  * that transitions the object from state #3 or #7 (allocated, constructed, not
325  * yet in use) to state #4 (in use, valid). That's important because the move
326  * function has to check the validity of the pointer before it can safely
327  * acquire the lock protecting the collection where it expects to find known
328  * objects.
329  *
330  * This method of distinguishing known objects observes the usual symmetry:
331  * invalidating the designated pointer is the first thing the client does before
332  * freeing the object, and setting the designated pointer is the last thing the
333  * client does after allocating the object. Of course, the client is not
334  * required to use this method. Fundamentally, how the client recognizes known
335  * objects is completely up to the client, but this method is recommended as an
336  * efficient and safe way to take advantage of the guarantees made by kmem. If
337  * the entire object is arbitrary data without any markable bits from a suitable
338  * pointer member, then the client must find some other method, such as
339  * searching a hash table of known objects.
340  *
341  * 2.5 Preventing Objects From Moving
342  *
343  * Besides a way to distinguish known objects, the other thing that the client
344  * needs is a strategy to ensure that an object will not move while the client
345  * is actively using it. The details of satisfying this requirement tend to be
346  * highly cache-specific. It might seem that the same rules that let a client
347  * remove an object safely should also decide when an object can be moved
348  * safely. However, any object state that makes a removal attempt invalid is
349  * likely to be long-lasting for objects that the client does not expect to
350  * remove. kmem knows nothing about the object state and is equally likely (from
351  * the client's point of view) to request a move for any object in the cache,
352  * whether prepared for removal or not. Even a low percentage of objects stuck
353  * in place by unremovability will defeat the consolidator if the stuck objects
354  * are the same long-lived allocations likely to hold slabs hostage.
355  * Fundamentally, the consolidator is not aimed at common cases. Severe external
356  * fragmentation is a worst case scenario manifested as sparsely allocated
357  * slabs, by definition a low percentage of the cache's objects. When deciding
358  * what makes an object movable, keep in mind the goal of the consolidator: to
359  * bring worst-case external fragmentation within the limits guaranteed for
360  * internal fragmentation. Removability is a poor criterion if it is likely to
361  * exclude more than an insignificant percentage of objects for long periods of
362  * time.
363  *
364  * A tricky general solution exists, and it has the advantage of letting you
365  * move any object at almost any moment, practically eliminating the likelihood
366  * that an object can hold a slab hostage. However, if there is a cache-specific
367  * way to ensure that an object is not actively in use in the vast majority of
368  * cases, a simpler solution that leverages this cache-specific knowledge is
369  * preferred.
370  *
371  * 2.5.1 Cache-Specific Solution
372  *
373  * As an example of a cache-specific solution, the ZFS znode cache takes
374  * advantage of the fact that the vast majority of znodes are only being
375  * referenced from the DNLC. (A typical case might be a few hundred in active
376  * use and a hundred thousand in the DNLC.) In the move callback, after the ZFS
377  * client has established that it recognizes the znode and can access its fields
378  * safely (using the method described earlier), it then tests whether the znode
379  * is referenced by anything other than the DNLC. If so, it assumes that the
380  * znode may be in active use and is unsafe to move, so it drops its locks and
381  * returns KMEM_CBRC_LATER. The advantage of this strategy is that everywhere
382  * else znodes are used, no change is needed to protect against the possibility
383  * of the znode moving. The disadvantage is that it remains possible for an
384  * application to hold a znode slab hostage with an open file descriptor.
385  * However, this case ought to be rare and the consolidator has a way to deal
386  * with it: If the client responds KMEM_CBRC_LATER repeatedly for the same
387  * object, kmem eventually stops believing it and treats the slab as if the
388  * client had responded KMEM_CBRC_NO. Having marked the hostage slab, kmem can
389  * then focus on getting it off of the partial slab list by allocating rather
390  * than freeing all of its objects. (Either way of getting a slab off the
391  * free list reduces fragmentation.)
392  *
393  * 2.5.2 General Solution
394  *
395  * The general solution, on the other hand, requires an explicit hold everywhere
396  * the object is used to prevent it from moving. To keep the client locking
397  * strategy as uncomplicated as possible, kmem guarantees the simplifying
398  * assumption that move callbacks are sequential, even across multiple caches.
399  * Internally, a global queue processed by a single thread supports all caches
400  * implementing the callback function. No matter how many caches supply a move
401  * function, the consolidator never moves more than one object at a time, so the
402  * client does not have to worry about tricky lock ordering involving several
403  * related objects from different kmem caches.
404  *
405  * The general solution implements the explicit hold as a read-write lock, which
406  * allows multiple readers to access an object from the cache simultaneously
407  * while a single writer is excluded from moving it. A single rwlock for the
408  * entire cache would lock out all threads from using any of the cache's objects
409  * even though only a single object is being moved, so to reduce contention,
410  * the client can fan out the single rwlock into an array of rwlocks hashed by
411  * the object address, making it probable that moving one object will not
412  * prevent other threads from using a different object. The rwlock cannot be a
413  * member of the object itself, because the possibility of the object moving
414  * makes it unsafe to access any of the object's fields until the lock is
415  * acquired.
416  *
417  * Assuming a small, fixed number of locks, it's possible that multiple objects
418  * will hash to the same lock. A thread that needs to use multiple objects in
419  * the same function may acquire the same lock multiple times. Since rwlocks are
420  * reentrant for readers, and since there is never more than a single writer at
421  * a time (assuming that the client acquires the lock as a writer only when
422  * moving an object inside the callback), there would seem to be no problem.
423  * However, a client locking multiple objects in the same function must handle
424  * one case of potential deadlock: Assume that thread A needs to prevent both
425  * object 1 and object 2 from moving, and thread B, the callback, meanwhile
426  * tries to move object 3. It's possible, if objects 1, 2, and 3 all hash to the
427  * same lock, that thread A will acquire the lock for object 1 as a reader
428  * before thread B sets the lock's write-wanted bit, preventing thread A from
429  * reacquiring the lock for object 2 as a reader. Unable to make forward
430  * progress, thread A will never release the lock for object 1, resulting in
431  * deadlock.
432  *
433  * There are two ways of avoiding the deadlock just described. The first is to
434  * use rw_tryenter() rather than rw_enter() in the callback function when
435  * attempting to acquire the lock as a writer. If tryenter discovers that the
436  * same object (or another object hashed to the same lock) is already in use, it
437  * aborts the callback and returns KMEM_CBRC_LATER. The second way is to use
438  * rprwlock_t (declared in common/fs/zfs/sys/rprwlock.h) instead of rwlock_t,
439  * since it allows a thread to acquire the lock as a reader in spite of a
440  * waiting writer. This second approach insists on moving the object now, no
441  * matter how many readers the move function must wait for in order to do so,
442  * and could delay the completion of the callback indefinitely (blocking
443  * callbacks to other clients). In practice, a less insistent callback using
444  * rw_tryenter() returns KMEM_CBRC_LATER infrequently enough that there seems
445  * little reason to use anything else.
446  *
447  * Avoiding deadlock is not the only problem that an implementation using an
448  * explicit hold needs to solve. Locking the object in the first place (to
449  * prevent it from moving) remains a problem, since the object could move
450  * between the time you obtain a pointer to the object and the time you acquire
451  * the rwlock hashed to that pointer value. Therefore the client needs to
452  * recheck the value of the pointer after acquiring the lock, drop the lock if
453  * the value has changed, and try again. This requires a level of indirection:
454  * something that points to the object rather than the object itself, that the
455  * client can access safely while attempting to acquire the lock. (The object
456  * itself cannot be referenced safely because it can move at any time.)
457  * The following lock-acquisition function takes whatever is safe to reference
458  * (arg), follows its pointer to the object (using function f), and tries as
459  * often as necessary to acquire the hashed lock and verify that the object
460  * still has not moved:
461  *
462  *      object_t *
463  *      object_hold(object_f f, void *arg)
464  *      {
465  *              object_t *op;
466  *
467  *              op = f(arg);
468  *              if (op == NULL) {
469  *                      return (NULL);
470  *              }
471  *
472  *              rw_enter(OBJECT_RWLOCK(op), RW_READER);
473  *              while (op != f(arg)) {
474  *                      rw_exit(OBJECT_RWLOCK(op));
475  *                      op = f(arg);
476  *                      if (op == NULL) {
477  *                              break;
478  *                      }
479  *                      rw_enter(OBJECT_RWLOCK(op), RW_READER);
480  *              }
481  *
482  *              return (op);
483  *      }
484  *
485  * The OBJECT_RWLOCK macro hashes the object address to obtain the rwlock. The
486  * lock reacquisition loop, while necessary, almost never executes. The function
487  * pointer f (used to obtain the object pointer from arg) has the following type
488  * definition:
489  *
490  *      typedef object_t *(*object_f)(void *arg);
491  *
492  * An object_f implementation is likely to be as simple as accessing a structure
493  * member:
494  *
495  *      object_t *
496  *      s_object(void *arg)
497  *      {
498  *              something_t *sp = arg;
499  *              return (sp->s_object);
500  *      }
501  *
502  * The flexibility of a function pointer allows the path to the object to be
503  * arbitrarily complex and also supports the notion that depending on where you
504  * are using the object, you may need to get it from someplace different.
505  *
506  * The function that releases the explicit hold is simpler because it does not
507  * have to worry about the object moving:
508  *
509  *      void
510  *      object_rele(object_t *op)
511  *      {
512  *              rw_exit(OBJECT_RWLOCK(op));
513  *      }
514  *
515  * The caller is spared these details so that obtaining and releasing an
516  * explicit hold feels like a simple mutex_enter()/mutex_exit() pair. The caller
517  * of object_hold() only needs to know that the returned object pointer is valid
518  * if not NULL and that the object will not move until released.
519  *
520  * Although object_hold() prevents an object from moving, it does not prevent it
521  * from being freed. The caller must take measures before calling object_hold()
522  * (afterwards is too late) to ensure that the held object cannot be freed. The
523  * caller must do so without accessing the unsafe object reference, so any lock
524  * or reference count used to ensure the continued existence of the object must
525  * live outside the object itself.
526  *
527  * Obtaining a new object is a special case where an explicit hold is impossible
528  * for the caller. Any function that returns a newly allocated object (either as
529  * a return value, or as an in-out paramter) must return it already held; after
530  * the caller gets it is too late, since the object cannot be safely accessed
531  * without the level of indirection described earlier. The following
532  * object_alloc() example uses the same code shown earlier to transition a new
533  * object into the state of being recognized (by the client) as a known object.
534  * The function must acquire the hold (rw_enter) before that state transition
535  * makes the object movable:
536  *
537  *      static object_t *
538  *      object_alloc(container_t *container)
539  *      {
540  *              object_t *object = kmem_cache_alloc(object_cache, 0);
541  *              ... set any initial state not set by the constructor ...
542  *              rw_enter(OBJECT_RWLOCK(object), RW_READER);
543  *              mutex_enter(&container->c_objects_lock);
544  *              list_insert_tail(&container->c_objects, object);
545  *              membar_producer();
546  *              object->o_container = container;
547  *              mutex_exit(&container->c_objects_lock);
548  *              return (object);
549  *      }
550  *
551  * Functions that implicitly acquire an object hold (any function that calls
552  * object_alloc() to supply an object for the caller) need to be carefully noted
553  * so that the matching object_rele() is not neglected. Otherwise, leaked holds
554  * prevent all objects hashed to the affected rwlocks from ever being moved.
555  *
556  * The pointer to a held object can be hashed to the holding rwlock even after
557  * the object has been freed. Although it is possible to release the hold
558  * after freeing the object, you may decide to release the hold implicitly in
559  * whatever function frees the object, so as to release the hold as soon as
560  * possible, and for the sake of symmetry with the function that implicitly
561  * acquires the hold when it allocates the object. Here, object_free() releases
562  * the hold acquired by object_alloc(). Its implicit object_rele() forms a
563  * matching pair with object_hold():
564  *
565  *      void
566  *      object_free(object_t *object)
567  *      {
568  *              container_t *container;
569  *
570  *              ASSERT(object_held(object));
571  *              container = object->o_container;
572  *              mutex_enter(&container->c_objects_lock);
573  *              object->o_container =
574  *                  (void *)((uintptr_t)object->o_container | 0x1);
575  *              list_remove(&container->c_objects, object);
576  *              mutex_exit(&container->c_objects_lock);
577  *              object_rele(object);
578  *              kmem_cache_free(object_cache, object);
579  *      }
580  *
581  * Note that object_free() cannot safely accept an object pointer as an argument
582  * unless the object is already held. Any function that calls object_free()
583  * needs to be carefully noted since it similarly forms a matching pair with
584  * object_hold().
585  *
586  * To complete the picture, the following callback function implements the
587  * general solution by moving objects only if they are currently unheld:
588  *
589  *      static kmem_cbrc_t
590  *      object_move(void *buf, void *newbuf, size_t size, void *arg)
591  *      {
592  *              object_t *op = buf, *np = newbuf;
593  *              container_t *container;
594  *
595  *              container = op->o_container;
596  *              if ((uintptr_t)container & 0x3) {
597  *                      return (KMEM_CBRC_DONT_KNOW);
598  *              }
599  *
600  *	        // Ensure that the container structure does not go away.
601  *              if (container_hold(container) == 0) {
602  *                      return (KMEM_CBRC_DONT_KNOW);
603  *              }
604  *
605  *              mutex_enter(&container->c_objects_lock);
606  *              if (container != op->o_container) {
607  *                      mutex_exit(&container->c_objects_lock);
608  *                      container_rele(container);
609  *                      return (KMEM_CBRC_DONT_KNOW);
610  *              }
611  *
612  *              if (rw_tryenter(OBJECT_RWLOCK(op), RW_WRITER) == 0) {
613  *                      mutex_exit(&container->c_objects_lock);
614  *                      container_rele(container);
615  *                      return (KMEM_CBRC_LATER);
616  *              }
617  *
618  *              object_move_impl(op, np); // critical section
619  *              rw_exit(OBJECT_RWLOCK(op));
620  *
621  *              op->o_container = (void *)((uintptr_t)op->o_container | 0x1);
622  *              list_link_replace(&op->o_link_node, &np->o_link_node);
623  *              mutex_exit(&container->c_objects_lock);
624  *              container_rele(container);
625  *              return (KMEM_CBRC_YES);
626  *      }
627  *
628  * Note that object_move() must invalidate the designated o_container pointer of
629  * the old object in the same way that object_free() does, since kmem will free
630  * the object in response to the KMEM_CBRC_YES return value.
631  *
632  * The lock order in object_move() differs from object_alloc(), which locks
633  * OBJECT_RWLOCK first and &container->c_objects_lock second, but as long as the
634  * callback uses rw_tryenter() (preventing the deadlock described earlier), it's
635  * not a problem. Holding the lock on the object list in the example above
636  * through the entire callback not only prevents the object from going away, it
637  * also allows you to lock the list elsewhere and know that none of its elements
638  * will move during iteration.
639  *
640  * Adding an explicit hold everywhere an object from the cache is used is tricky
641  * and involves much more change to client code than a cache-specific solution
642  * that leverages existing state to decide whether or not an object is
643  * movable. However, this approach has the advantage that no object remains
644  * immovable for any significant length of time, making it extremely unlikely
645  * that long-lived allocations can continue holding slabs hostage; and it works
646  * for any cache.
647  *
648  * 3. Consolidator Implementation
649  *
650  * Once the client supplies a move function that a) recognizes known objects and
651  * b) avoids moving objects that are actively in use, the remaining work is up
652  * to the consolidator to decide which objects to move and when to issue
653  * callbacks.
654  *
655  * The consolidator relies on the fact that a cache's slabs are ordered by
656  * usage. Each slab has a fixed number of objects. Depending on the slab's
657  * "color" (the offset of the first object from the beginning of the slab;
658  * offsets are staggered to mitigate false sharing of cache lines) it is either
659  * the maximum number of objects per slab determined at cache creation time or
660  * else the number closest to the maximum that fits within the space remaining
661  * after the initial offset. A completely allocated slab may contribute some
662  * internal fragmentation (per-slab overhead) but no external fragmentation, so
663  * it is of no interest to the consolidator. At the other extreme, slabs whose
664  * objects have all been freed to the slab are released to the virtual memory
665  * (VM) subsystem (objects freed to magazines are still allocated as far as the
666  * slab is concerned). External fragmentation exists when there are slabs
667  * somewhere between these extremes. A partial slab has at least one but not all
668  * of its objects allocated. The more partial slabs, and the fewer allocated
669  * objects on each of them, the higher the fragmentation. Hence the
670  * consolidator's overall strategy is to reduce the number of partial slabs by
671  * moving allocated objects from the least allocated slabs to the most allocated
672  * slabs.
673  *
674  * Partial slabs are kept in an AVL tree ordered by usage. Completely allocated
675  * slabs are kept separately in an unordered list. Since the majority of slabs
676  * tend to be completely allocated (a typical unfragmented cache may have
677  * thousands of complete slabs and only a single partial slab), separating
678  * complete slabs improves the efficiency of partial slab ordering, since the
679  * complete slabs do not affect the depth or balance of the AVL tree. This
680  * ordered sequence of partial slabs acts as a "free list" supplying objects for
681  * allocation requests.
682  *
683  * Objects are always allocated from the first partial slab in the free list,
684  * where the allocation is most likely to eliminate a partial slab (by
685  * completely allocating it). Conversely, when a single object from a completely
686  * allocated slab is freed to the slab, that slab is added to the front of the
687  * free list. Since most free list activity involves highly allocated slabs
688  * coming and going at the front of the list, slabs tend naturally toward the
689  * ideal order: highly allocated at the front, sparsely allocated at the back.
690  * Slabs with few allocated objects are likely to become completely free if they
691  * keep a safe distance away from the front of the free list. Slab misorders
692  * interfere with the natural tendency of slabs to become completely free or
693  * completely allocated. For example, a slab with a single allocated object
694  * needs only a single free to escape the cache; its natural desire is
695  * frustrated when it finds itself at the front of the list where a second
696  * allocation happens just before the free could have released it. Another slab
697  * with all but one object allocated might have supplied the buffer instead, so
698  * that both (as opposed to neither) of the slabs would have been taken off the
699  * free list.
700  *
701  * Although slabs tend naturally toward the ideal order, misorders allowed by a
702  * simple list implementation defeat the consolidator's strategy of merging
703  * least- and most-allocated slabs. Without an AVL tree to guarantee order, kmem
704  * needs another way to fix misorders to optimize its callback strategy. One
705  * approach is to periodically scan a limited number of slabs, advancing a
706  * marker to hold the current scan position, and to move extreme misorders to
707  * the front or back of the free list and to the front or back of the current
708  * scan range. By making consecutive scan ranges overlap by one slab, the least
709  * allocated slab in the current range can be carried along from the end of one
710  * scan to the start of the next.
711  *
712  * Maintaining partial slabs in an AVL tree relieves kmem of this additional
713  * task, however. Since most of the cache's activity is in the magazine layer,
714  * and allocations from the slab layer represent only a startup cost, the
715  * overhead of maintaining a balanced tree is not a significant concern compared
716  * to the opportunity of reducing complexity by eliminating the partial slab
717  * scanner just described. The overhead of an AVL tree is minimized by
718  * maintaining only partial slabs in the tree and keeping completely allocated
719  * slabs separately in a list. To avoid increasing the size of the slab
720  * structure the AVL linkage pointers are reused for the slab's list linkage,
721  * since the slab will always be either partial or complete, never stored both
722  * ways at the same time. To further minimize the overhead of the AVL tree the
723  * compare function that orders partial slabs by usage divides the range of
724  * allocated object counts into bins such that counts within the same bin are
725  * considered equal. Binning partial slabs makes it less likely that allocating
726  * or freeing a single object will change the slab's order, requiring a tree
727  * reinsertion (an avl_remove() followed by an avl_add(), both potentially
728  * requiring some rebalancing of the tree). Allocation counts closest to
729  * completely free and completely allocated are left unbinned (finely sorted) to
730  * better support the consolidator's strategy of merging slabs at either
731  * extreme.
732  *
733  * 3.1 Assessing Fragmentation and Selecting Candidate Slabs
734  *
735  * The consolidator piggybacks on the kmem maintenance thread and is called on
736  * the same interval as kmem_cache_update(), once per cache every fifteen
737  * seconds. kmem maintains a running count of unallocated objects in the slab
738  * layer (cache_bufslab). The consolidator checks whether that number exceeds
739  * 12.5% (1/8) of the total objects in the cache (cache_buftotal), and whether
740  * there is a significant number of slabs in the cache (arbitrarily a minimum
741  * 101 total slabs). Unused objects that have fallen out of the magazine layer's
742  * working set are included in the assessment, and magazines in the depot are
743  * reaped if those objects would lift cache_bufslab above the fragmentation
744  * threshold. Once the consolidator decides that a cache is fragmented, it looks
745  * for a candidate slab to reclaim, starting at the end of the partial slab free
746  * list and scanning backwards. At first the consolidator is choosy: only a slab
747  * with fewer than 12.5% (1/8) of its objects allocated qualifies (or else a
748  * single allocated object, regardless of percentage). If there is difficulty
749  * finding a candidate slab, kmem raises the allocation threshold incrementally,
750  * up to a maximum 87.5% (7/8), so that eventually the consolidator will reduce
751  * external fragmentation (unused objects on the free list) below 12.5% (1/8),
752  * even in the worst case of every slab in the cache being almost 7/8 allocated.
753  * The threshold can also be lowered incrementally when candidate slabs are easy
754  * to find, and the threshold is reset to the minimum 1/8 as soon as the cache
755  * is no longer fragmented.
756  *
757  * 3.2 Generating Callbacks
758  *
759  * Once an eligible slab is chosen, a callback is generated for every allocated
760  * object on the slab, in the hope that the client will move everything off the
761  * slab and make it reclaimable. Objects selected as move destinations are
762  * chosen from slabs at the front of the free list. Assuming slabs in the ideal
763  * order (most allocated at the front, least allocated at the back) and a
764  * cooperative client, the consolidator will succeed in removing slabs from both
765  * ends of the free list, completely allocating on the one hand and completely
766  * freeing on the other. Objects selected as move destinations are allocated in
767  * the kmem maintenance thread where move requests are enqueued. A separate
768  * callback thread removes pending callbacks from the queue and calls the
769  * client. The separate thread ensures that client code (the move function) does
770  * not interfere with internal kmem maintenance tasks. A map of pending
771  * callbacks keyed by object address (the object to be moved) is checked to
772  * ensure that duplicate callbacks are not generated for the same object.
773  * Allocating the move destination (the object to move to) prevents subsequent
774  * callbacks from selecting the same destination as an earlier pending callback.
775  *
776  * Move requests can also be generated by kmem_cache_reap() when the system is
777  * desperate for memory and by kmem_cache_move_notify(), called by the client to
778  * notify kmem that a move refused earlier with KMEM_CBRC_LATER is now possible.
779  * The map of pending callbacks is protected by the same lock that protects the
780  * slab layer.
781  *
782  * When the system is desperate for memory, kmem does not bother to determine
783  * whether or not the cache exceeds the fragmentation threshold, but tries to
784  * consolidate as many slabs as possible. Normally, the consolidator chews
785  * slowly, one sparsely allocated slab at a time during each maintenance
786  * interval that the cache is fragmented. When desperate, the consolidator
787  * starts at the last partial slab and enqueues callbacks for every allocated
788  * object on every partial slab, working backwards until it reaches the first
789  * partial slab. The first partial slab, meanwhile, advances in pace with the
790  * consolidator as allocations to supply move destinations for the enqueued
791  * callbacks use up the highly allocated slabs at the front of the free list.
792  * Ideally, the overgrown free list collapses like an accordion, starting at
793  * both ends and ending at the center with a single partial slab.
794  *
795  * 3.3 Client Responses
796  *
797  * When the client returns KMEM_CBRC_NO in response to the move callback, kmem
798  * marks the slab that supplied the stuck object non-reclaimable and moves it to
799  * front of the free list. The slab remains marked as long as it remains on the
800  * free list, and it appears more allocated to the partial slab compare function
801  * than any unmarked slab, no matter how many of its objects are allocated.
802  * Since even one immovable object ties up the entire slab, the goal is to
803  * completely allocate any slab that cannot be completely freed. kmem does not
804  * bother generating callbacks to move objects from a marked slab unless the
805  * system is desperate.
806  *
807  * When the client responds KMEM_CBRC_LATER, kmem increments a count for the
808  * slab. If the client responds LATER too many times, kmem disbelieves and
809  * treats the response as a NO. The count is cleared when the slab is taken off
810  * the partial slab list or when the client moves one of the slab's objects.
811  *
812  * 4. Observability
813  *
814  * A kmem cache's external fragmentation is best observed with 'mdb -k' using
815  * the ::kmem_slabs dcmd. For a complete description of the command, enter
816  * '::help kmem_slabs' at the mdb prompt.
817  */
818 
819 #include <sys/kmem_impl.h>
820 #include <sys/vmem_impl.h>
821 #include <sys/param.h>
822 #include <sys/sysmacros.h>
823 #include <sys/vm.h>
824 #include <sys/proc.h>
825 #include <sys/tuneable.h>
826 #include <sys/systm.h>
827 #include <sys/cmn_err.h>
828 #include <sys/debug.h>
829 #include <sys/sdt.h>
830 #include <sys/mutex.h>
831 #include <sys/bitmap.h>
832 #include <sys/atomic.h>
833 #include <sys/kobj.h>
834 #include <sys/disp.h>
835 #include <vm/seg_kmem.h>
836 #include <sys/log.h>
837 #include <sys/callb.h>
838 #include <sys/taskq.h>
839 #include <sys/modctl.h>
840 #include <sys/reboot.h>
841 #include <sys/id32.h>
842 #include <sys/zone.h>
843 #include <sys/netstack.h>
844 #ifdef	DEBUG
845 #include <sys/random.h>
846 #endif
847 
848 extern void streams_msg_init(void);
849 extern int segkp_fromheap;
850 extern void segkp_cache_free(void);
851 extern int callout_init_done;
852 
853 struct kmem_cache_kstat {
854 	kstat_named_t	kmc_buf_size;
855 	kstat_named_t	kmc_align;
856 	kstat_named_t	kmc_chunk_size;
857 	kstat_named_t	kmc_slab_size;
858 	kstat_named_t	kmc_alloc;
859 	kstat_named_t	kmc_alloc_fail;
860 	kstat_named_t	kmc_free;
861 	kstat_named_t	kmc_depot_alloc;
862 	kstat_named_t	kmc_depot_free;
863 	kstat_named_t	kmc_depot_contention;
864 	kstat_named_t	kmc_slab_alloc;
865 	kstat_named_t	kmc_slab_free;
866 	kstat_named_t	kmc_buf_constructed;
867 	kstat_named_t	kmc_buf_avail;
868 	kstat_named_t	kmc_buf_inuse;
869 	kstat_named_t	kmc_buf_total;
870 	kstat_named_t	kmc_buf_max;
871 	kstat_named_t	kmc_slab_create;
872 	kstat_named_t	kmc_slab_destroy;
873 	kstat_named_t	kmc_vmem_source;
874 	kstat_named_t	kmc_hash_size;
875 	kstat_named_t	kmc_hash_lookup_depth;
876 	kstat_named_t	kmc_hash_rescale;
877 	kstat_named_t	kmc_full_magazines;
878 	kstat_named_t	kmc_empty_magazines;
879 	kstat_named_t	kmc_magazine_size;
880 	kstat_named_t	kmc_reap; /* number of kmem_cache_reap() calls */
881 	kstat_named_t	kmc_defrag; /* attempts to defrag all partial slabs */
882 	kstat_named_t	kmc_scan; /* attempts to defrag one partial slab */
883 	kstat_named_t	kmc_move_callbacks; /* sum of yes, no, later, dn, dk */
884 	kstat_named_t	kmc_move_yes;
885 	kstat_named_t	kmc_move_no;
886 	kstat_named_t	kmc_move_later;
887 	kstat_named_t	kmc_move_dont_need;
888 	kstat_named_t	kmc_move_dont_know; /* obj unrecognized by client ... */
889 	kstat_named_t	kmc_move_hunt_found; /* ... but found in mag layer */
890 	kstat_named_t	kmc_move_slabs_freed; /* slabs freed by consolidator */
891 	kstat_named_t	kmc_move_reclaimable; /* buffers, if consolidator ran */
892 } kmem_cache_kstat = {
893 	{ "buf_size",		KSTAT_DATA_UINT64 },
894 	{ "align",		KSTAT_DATA_UINT64 },
895 	{ "chunk_size",		KSTAT_DATA_UINT64 },
896 	{ "slab_size",		KSTAT_DATA_UINT64 },
897 	{ "alloc",		KSTAT_DATA_UINT64 },
898 	{ "alloc_fail",		KSTAT_DATA_UINT64 },
899 	{ "free",		KSTAT_DATA_UINT64 },
900 	{ "depot_alloc",	KSTAT_DATA_UINT64 },
901 	{ "depot_free",		KSTAT_DATA_UINT64 },
902 	{ "depot_contention",	KSTAT_DATA_UINT64 },
903 	{ "slab_alloc",		KSTAT_DATA_UINT64 },
904 	{ "slab_free",		KSTAT_DATA_UINT64 },
905 	{ "buf_constructed",	KSTAT_DATA_UINT64 },
906 	{ "buf_avail",		KSTAT_DATA_UINT64 },
907 	{ "buf_inuse",		KSTAT_DATA_UINT64 },
908 	{ "buf_total",		KSTAT_DATA_UINT64 },
909 	{ "buf_max",		KSTAT_DATA_UINT64 },
910 	{ "slab_create",	KSTAT_DATA_UINT64 },
911 	{ "slab_destroy",	KSTAT_DATA_UINT64 },
912 	{ "vmem_source",	KSTAT_DATA_UINT64 },
913 	{ "hash_size",		KSTAT_DATA_UINT64 },
914 	{ "hash_lookup_depth",	KSTAT_DATA_UINT64 },
915 	{ "hash_rescale",	KSTAT_DATA_UINT64 },
916 	{ "full_magazines",	KSTAT_DATA_UINT64 },
917 	{ "empty_magazines",	KSTAT_DATA_UINT64 },
918 	{ "magazine_size",	KSTAT_DATA_UINT64 },
919 	{ "reap",		KSTAT_DATA_UINT64 },
920 	{ "defrag",		KSTAT_DATA_UINT64 },
921 	{ "scan",		KSTAT_DATA_UINT64 },
922 	{ "move_callbacks",	KSTAT_DATA_UINT64 },
923 	{ "move_yes",		KSTAT_DATA_UINT64 },
924 	{ "move_no",		KSTAT_DATA_UINT64 },
925 	{ "move_later",		KSTAT_DATA_UINT64 },
926 	{ "move_dont_need",	KSTAT_DATA_UINT64 },
927 	{ "move_dont_know",	KSTAT_DATA_UINT64 },
928 	{ "move_hunt_found",	KSTAT_DATA_UINT64 },
929 	{ "move_slabs_freed",	KSTAT_DATA_UINT64 },
930 	{ "move_reclaimable",	KSTAT_DATA_UINT64 },
931 };
932 
933 static kmutex_t kmem_cache_kstat_lock;
934 
935 /*
936  * The default set of caches to back kmem_alloc().
937  * These sizes should be reevaluated periodically.
938  *
939  * We want allocations that are multiples of the coherency granularity
940  * (64 bytes) to be satisfied from a cache which is a multiple of 64
941  * bytes, so that it will be 64-byte aligned.  For all multiples of 64,
942  * the next kmem_cache_size greater than or equal to it must be a
943  * multiple of 64.
944  *
945  * We split the table into two sections:  size <= 4k and size > 4k.  This
946  * saves a lot of space and cache footprint in our cache tables.
947  */
948 static const int kmem_alloc_sizes[] = {
949 	1 * 8,
950 	2 * 8,
951 	3 * 8,
952 	4 * 8,		5 * 8,		6 * 8,		7 * 8,
953 	4 * 16,		5 * 16,		6 * 16,		7 * 16,
954 	4 * 32,		5 * 32,		6 * 32,		7 * 32,
955 	4 * 64,		5 * 64,		6 * 64,		7 * 64,
956 	4 * 128,	5 * 128,	6 * 128,	7 * 128,
957 	P2ALIGN(8192 / 7, 64),
958 	P2ALIGN(8192 / 6, 64),
959 	P2ALIGN(8192 / 5, 64),
960 	P2ALIGN(8192 / 4, 64),
961 	P2ALIGN(8192 / 3, 64),
962 	P2ALIGN(8192 / 2, 64),
963 };
964 
965 static const int kmem_big_alloc_sizes[] = {
966 	2 * 4096,	3 * 4096,
967 	2 * 8192,	3 * 8192,
968 	4 * 8192,	5 * 8192,	6 * 8192,	7 * 8192,
969 	8 * 8192,	9 * 8192,	10 * 8192,	11 * 8192,
970 	12 * 8192,	13 * 8192,	14 * 8192,	15 * 8192,
971 	16 * 8192
972 };
973 
974 #define	KMEM_MAXBUF		4096
975 #define	KMEM_BIG_MAXBUF_32BIT	32768
976 #define	KMEM_BIG_MAXBUF		131072
977 
978 #define	KMEM_BIG_MULTIPLE	4096	/* big_alloc_sizes must be a multiple */
979 #define	KMEM_BIG_SHIFT		12	/* lg(KMEM_BIG_MULTIPLE) */
980 
981 static kmem_cache_t *kmem_alloc_table[KMEM_MAXBUF >> KMEM_ALIGN_SHIFT];
982 static kmem_cache_t *kmem_big_alloc_table[KMEM_BIG_MAXBUF >> KMEM_BIG_SHIFT];
983 
984 #define	KMEM_ALLOC_TABLE_MAX	(KMEM_MAXBUF >> KMEM_ALIGN_SHIFT)
985 static size_t kmem_big_alloc_table_max = 0;	/* # of filled elements */
986 
987 static kmem_magtype_t kmem_magtype[] = {
988 	{ 1,	8,	3200,	65536	},
989 	{ 3,	16,	256,	32768	},
990 	{ 7,	32,	64,	16384	},
991 	{ 15,	64,	0,	8192	},
992 	{ 31,	64,	0,	4096	},
993 	{ 47,	64,	0,	2048	},
994 	{ 63,	64,	0,	1024	},
995 	{ 95,	64,	0,	512	},
996 	{ 143,	64,	0,	0	},
997 };
998 
999 static uint32_t kmem_reaping;
1000 static uint32_t kmem_reaping_idspace;
1001 
1002 /*
1003  * kmem tunables
1004  */
1005 clock_t kmem_reap_interval;	/* cache reaping rate [15 * HZ ticks] */
1006 int kmem_depot_contention = 3;	/* max failed tryenters per real interval */
1007 pgcnt_t kmem_reapahead = 0;	/* start reaping N pages before pageout */
1008 int kmem_panic = 1;		/* whether to panic on error */
1009 int kmem_logging = 1;		/* kmem_log_enter() override */
1010 uint32_t kmem_mtbf = 0;		/* mean time between failures [default: off] */
1011 size_t kmem_transaction_log_size; /* transaction log size [2% of memory] */
1012 size_t kmem_content_log_size;	/* content log size [2% of memory] */
1013 size_t kmem_failure_log_size;	/* failure log [4 pages per CPU] */
1014 size_t kmem_slab_log_size;	/* slab create log [4 pages per CPU] */
1015 size_t kmem_zerosized_log_size;	/* zero-sized log [4 pages per CPU] */
1016 size_t kmem_content_maxsave = 256; /* KMF_CONTENTS max bytes to log */
1017 size_t kmem_lite_minsize = 0;	/* minimum buffer size for KMF_LITE */
1018 size_t kmem_lite_maxalign = 1024; /* maximum buffer alignment for KMF_LITE */
1019 int kmem_lite_pcs = 4;		/* number of PCs to store in KMF_LITE mode */
1020 size_t kmem_maxverify;		/* maximum bytes to inspect in debug routines */
1021 size_t kmem_minfirewall;	/* hardware-enforced redzone threshold */
1022 
1023 #ifdef DEBUG
1024 int kmem_warn_zerosized = 1;	/* whether to warn on zero-sized KM_SLEEP */
1025 #else
1026 int kmem_warn_zerosized = 0;	/* whether to warn on zero-sized KM_SLEEP */
1027 #endif
1028 
1029 int kmem_panic_zerosized = 0;	/* whether to panic on zero-sized KM_SLEEP */
1030 
1031 #ifdef _LP64
1032 size_t	kmem_max_cached = KMEM_BIG_MAXBUF;	/* maximum kmem_alloc cache */
1033 #else
1034 size_t	kmem_max_cached = KMEM_BIG_MAXBUF_32BIT; /* maximum kmem_alloc cache */
1035 #endif
1036 
1037 #ifdef DEBUG
1038 int kmem_flags = KMF_AUDIT | KMF_DEADBEEF | KMF_REDZONE | KMF_CONTENTS;
1039 #else
1040 int kmem_flags = 0;
1041 #endif
1042 int kmem_ready;
1043 
1044 static kmem_cache_t	*kmem_slab_cache;
1045 static kmem_cache_t	*kmem_bufctl_cache;
1046 static kmem_cache_t	*kmem_bufctl_audit_cache;
1047 
1048 static kmutex_t		kmem_cache_lock;	/* inter-cache linkage only */
1049 static list_t		kmem_caches;
1050 
1051 static taskq_t		*kmem_taskq;
1052 static kmutex_t		kmem_flags_lock;
1053 static vmem_t		*kmem_metadata_arena;
1054 static vmem_t		*kmem_msb_arena;	/* arena for metadata caches */
1055 static vmem_t		*kmem_cache_arena;
1056 static vmem_t		*kmem_hash_arena;
1057 static vmem_t		*kmem_log_arena;
1058 static vmem_t		*kmem_oversize_arena;
1059 static vmem_t		*kmem_va_arena;
1060 static vmem_t		*kmem_default_arena;
1061 static vmem_t		*kmem_firewall_va_arena;
1062 static vmem_t		*kmem_firewall_arena;
1063 
1064 static int		kmem_zerosized;		/* # of zero-sized allocs */
1065 
1066 /*
1067  * kmem slab consolidator thresholds (tunables)
1068  */
1069 size_t kmem_frag_minslabs = 101;	/* minimum total slabs */
1070 size_t kmem_frag_numer = 1;		/* free buffers (numerator) */
1071 size_t kmem_frag_denom = KMEM_VOID_FRACTION; /* buffers (denominator) */
1072 /*
1073  * Maximum number of slabs from which to move buffers during a single
1074  * maintenance interval while the system is not low on memory.
1075  */
1076 size_t kmem_reclaim_max_slabs = 1;
1077 /*
1078  * Number of slabs to scan backwards from the end of the partial slab list
1079  * when searching for buffers to relocate.
1080  */
1081 size_t kmem_reclaim_scan_range = 12;
1082 
1083 /* consolidator knobs */
1084 boolean_t kmem_move_noreap;
1085 boolean_t kmem_move_blocked;
1086 boolean_t kmem_move_fulltilt;
1087 boolean_t kmem_move_any_partial;
1088 
1089 #ifdef	DEBUG
1090 /*
1091  * kmem consolidator debug tunables:
1092  * Ensure code coverage by occasionally running the consolidator even when the
1093  * caches are not fragmented (they may never be). These intervals are mean time
1094  * in cache maintenance intervals (kmem_cache_update).
1095  */
1096 uint32_t kmem_mtb_move = 60;	/* defrag 1 slab (~15min) */
1097 uint32_t kmem_mtb_reap = 1800;	/* defrag all slabs (~7.5hrs) */
1098 #endif	/* DEBUG */
1099 
1100 static kmem_cache_t	*kmem_defrag_cache;
1101 static kmem_cache_t	*kmem_move_cache;
1102 static taskq_t		*kmem_move_taskq;
1103 
1104 static void kmem_cache_scan(kmem_cache_t *);
1105 static void kmem_cache_defrag(kmem_cache_t *);
1106 static void kmem_slab_prefill(kmem_cache_t *, kmem_slab_t *);
1107 
1108 
1109 kmem_log_header_t	*kmem_transaction_log;
1110 kmem_log_header_t	*kmem_content_log;
1111 kmem_log_header_t	*kmem_failure_log;
1112 kmem_log_header_t	*kmem_slab_log;
1113 kmem_log_header_t	*kmem_zerosized_log;
1114 
1115 static int		kmem_lite_count; /* # of PCs in kmem_buftag_lite_t */
1116 
1117 #define	KMEM_BUFTAG_LITE_ENTER(bt, count, caller)			\
1118 	if ((count) > 0) {						\
1119 		pc_t *_s = ((kmem_buftag_lite_t *)(bt))->bt_history;	\
1120 		pc_t *_e;						\
1121 		/* memmove() the old entries down one notch */		\
1122 		for (_e = &_s[(count) - 1]; _e > _s; _e--)		\
1123 			*_e = *(_e - 1);				\
1124 		*_s = (uintptr_t)(caller);				\
1125 	}
1126 
1127 #define	KMERR_MODIFIED	0	/* buffer modified while on freelist */
1128 #define	KMERR_REDZONE	1	/* redzone violation (write past end of buf) */
1129 #define	KMERR_DUPFREE	2	/* freed a buffer twice */
1130 #define	KMERR_BADADDR	3	/* freed a bad (unallocated) address */
1131 #define	KMERR_BADBUFTAG	4	/* buftag corrupted */
1132 #define	KMERR_BADBUFCTL	5	/* bufctl corrupted */
1133 #define	KMERR_BADCACHE	6	/* freed a buffer to the wrong cache */
1134 #define	KMERR_BADSIZE	7	/* alloc size != free size */
1135 #define	KMERR_BADBASE	8	/* buffer base address wrong */
1136 
1137 struct {
1138 	hrtime_t	kmp_timestamp;	/* timestamp of panic */
1139 	int		kmp_error;	/* type of kmem error */
1140 	void		*kmp_buffer;	/* buffer that induced panic */
1141 	void		*kmp_realbuf;	/* real start address for buffer */
1142 	kmem_cache_t	*kmp_cache;	/* buffer's cache according to client */
1143 	kmem_cache_t	*kmp_realcache;	/* actual cache containing buffer */
1144 	kmem_slab_t	*kmp_slab;	/* slab accoring to kmem_findslab() */
1145 	kmem_bufctl_t	*kmp_bufctl;	/* bufctl */
1146 } kmem_panic_info;
1147 
1148 
1149 static void
copy_pattern(uint64_t pattern,void * buf_arg,size_t size)1150 copy_pattern(uint64_t pattern, void *buf_arg, size_t size)
1151 {
1152 	uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1153 	uint64_t *buf = buf_arg;
1154 
1155 	while (buf < bufend)
1156 		*buf++ = pattern;
1157 }
1158 
1159 static void *
verify_pattern(uint64_t pattern,void * buf_arg,size_t size)1160 verify_pattern(uint64_t pattern, void *buf_arg, size_t size)
1161 {
1162 	uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1163 	uint64_t *buf;
1164 
1165 	for (buf = buf_arg; buf < bufend; buf++)
1166 		if (*buf != pattern)
1167 			return (buf);
1168 	return (NULL);
1169 }
1170 
1171 static void *
verify_and_copy_pattern(uint64_t old,uint64_t new,void * buf_arg,size_t size)1172 verify_and_copy_pattern(uint64_t old, uint64_t new, void *buf_arg, size_t size)
1173 {
1174 	uint64_t *bufend = (uint64_t *)((char *)buf_arg + size);
1175 	uint64_t *buf;
1176 
1177 	for (buf = buf_arg; buf < bufend; buf++) {
1178 		if (*buf != old) {
1179 			copy_pattern(old, buf_arg,
1180 			    (char *)buf - (char *)buf_arg);
1181 			return (buf);
1182 		}
1183 		*buf = new;
1184 	}
1185 
1186 	return (NULL);
1187 }
1188 
1189 static void
kmem_cache_applyall(void (* func)(kmem_cache_t *),taskq_t * tq,int tqflag)1190 kmem_cache_applyall(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1191 {
1192 	kmem_cache_t *cp;
1193 
1194 	mutex_enter(&kmem_cache_lock);
1195 	for (cp = list_head(&kmem_caches); cp != NULL;
1196 	    cp = list_next(&kmem_caches, cp))
1197 		if (tq != NULL)
1198 			(void) taskq_dispatch(tq, (task_func_t *)func, cp,
1199 			    tqflag);
1200 		else
1201 			func(cp);
1202 	mutex_exit(&kmem_cache_lock);
1203 }
1204 
1205 static void
kmem_cache_applyall_id(void (* func)(kmem_cache_t *),taskq_t * tq,int tqflag)1206 kmem_cache_applyall_id(void (*func)(kmem_cache_t *), taskq_t *tq, int tqflag)
1207 {
1208 	kmem_cache_t *cp;
1209 
1210 	mutex_enter(&kmem_cache_lock);
1211 	for (cp = list_head(&kmem_caches); cp != NULL;
1212 	    cp = list_next(&kmem_caches, cp)) {
1213 		if (!(cp->cache_cflags & KMC_IDENTIFIER))
1214 			continue;
1215 		if (tq != NULL)
1216 			(void) taskq_dispatch(tq, (task_func_t *)func, cp,
1217 			    tqflag);
1218 		else
1219 			func(cp);
1220 	}
1221 	mutex_exit(&kmem_cache_lock);
1222 }
1223 
1224 /*
1225  * Debugging support.  Given a buffer address, find its slab.
1226  */
1227 static kmem_slab_t *
kmem_findslab(kmem_cache_t * cp,void * buf)1228 kmem_findslab(kmem_cache_t *cp, void *buf)
1229 {
1230 	kmem_slab_t *sp;
1231 
1232 	mutex_enter(&cp->cache_lock);
1233 	for (sp = list_head(&cp->cache_complete_slabs); sp != NULL;
1234 	    sp = list_next(&cp->cache_complete_slabs, sp)) {
1235 		if (KMEM_SLAB_MEMBER(sp, buf)) {
1236 			mutex_exit(&cp->cache_lock);
1237 			return (sp);
1238 		}
1239 	}
1240 	for (sp = avl_first(&cp->cache_partial_slabs); sp != NULL;
1241 	    sp = AVL_NEXT(&cp->cache_partial_slabs, sp)) {
1242 		if (KMEM_SLAB_MEMBER(sp, buf)) {
1243 			mutex_exit(&cp->cache_lock);
1244 			return (sp);
1245 		}
1246 	}
1247 	mutex_exit(&cp->cache_lock);
1248 
1249 	return (NULL);
1250 }
1251 
1252 static void
kmem_error(int error,kmem_cache_t * cparg,void * bufarg)1253 kmem_error(int error, kmem_cache_t *cparg, void *bufarg)
1254 {
1255 	kmem_buftag_t *btp = NULL;
1256 	kmem_bufctl_t *bcp = NULL;
1257 	kmem_cache_t *cp = cparg;
1258 	kmem_slab_t *sp;
1259 	uint64_t *off;
1260 	void *buf = bufarg;
1261 
1262 	kmem_logging = 0;	/* stop logging when a bad thing happens */
1263 
1264 	kmem_panic_info.kmp_timestamp = gethrtime();
1265 
1266 	sp = kmem_findslab(cp, buf);
1267 	if (sp == NULL) {
1268 		for (cp = list_tail(&kmem_caches); cp != NULL;
1269 		    cp = list_prev(&kmem_caches, cp)) {
1270 			if ((sp = kmem_findslab(cp, buf)) != NULL)
1271 				break;
1272 		}
1273 	}
1274 
1275 	if (sp == NULL) {
1276 		cp = NULL;
1277 		error = KMERR_BADADDR;
1278 	} else {
1279 		if (cp != cparg)
1280 			error = KMERR_BADCACHE;
1281 		else
1282 			buf = (char *)bufarg - ((uintptr_t)bufarg -
1283 			    (uintptr_t)sp->slab_base) % cp->cache_chunksize;
1284 		if (buf != bufarg)
1285 			error = KMERR_BADBASE;
1286 		if (cp->cache_flags & KMF_BUFTAG)
1287 			btp = KMEM_BUFTAG(cp, buf);
1288 		if (cp->cache_flags & KMF_HASH) {
1289 			mutex_enter(&cp->cache_lock);
1290 			for (bcp = *KMEM_HASH(cp, buf); bcp; bcp = bcp->bc_next)
1291 				if (bcp->bc_addr == buf)
1292 					break;
1293 			mutex_exit(&cp->cache_lock);
1294 			if (bcp == NULL && btp != NULL)
1295 				bcp = btp->bt_bufctl;
1296 			if (kmem_findslab(cp->cache_bufctl_cache, bcp) ==
1297 			    NULL || P2PHASE((uintptr_t)bcp, KMEM_ALIGN) ||
1298 			    bcp->bc_addr != buf) {
1299 				error = KMERR_BADBUFCTL;
1300 				bcp = NULL;
1301 			}
1302 		}
1303 	}
1304 
1305 	kmem_panic_info.kmp_error = error;
1306 	kmem_panic_info.kmp_buffer = bufarg;
1307 	kmem_panic_info.kmp_realbuf = buf;
1308 	kmem_panic_info.kmp_cache = cparg;
1309 	kmem_panic_info.kmp_realcache = cp;
1310 	kmem_panic_info.kmp_slab = sp;
1311 	kmem_panic_info.kmp_bufctl = bcp;
1312 
1313 	printf("kernel memory allocator: ");
1314 
1315 	switch (error) {
1316 
1317 	case KMERR_MODIFIED:
1318 		printf("buffer modified after being freed\n");
1319 		off = verify_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1320 		if (off == NULL)	/* shouldn't happen */
1321 			off = buf;
1322 		printf("modification occurred at offset 0x%lx "
1323 		    "(0x%llx replaced by 0x%llx)\n",
1324 		    (uintptr_t)off - (uintptr_t)buf,
1325 		    (longlong_t)KMEM_FREE_PATTERN, (longlong_t)*off);
1326 		break;
1327 
1328 	case KMERR_REDZONE:
1329 		printf("redzone violation: write past end of buffer\n");
1330 		break;
1331 
1332 	case KMERR_BADADDR:
1333 		printf("invalid free: buffer not in cache\n");
1334 		break;
1335 
1336 	case KMERR_DUPFREE:
1337 		printf("duplicate free: buffer freed twice\n");
1338 		break;
1339 
1340 	case KMERR_BADBUFTAG:
1341 		printf("boundary tag corrupted\n");
1342 		printf("bcp ^ bxstat = %lx, should be %lx\n",
1343 		    (intptr_t)btp->bt_bufctl ^ btp->bt_bxstat,
1344 		    KMEM_BUFTAG_FREE);
1345 		break;
1346 
1347 	case KMERR_BADBUFCTL:
1348 		printf("bufctl corrupted\n");
1349 		break;
1350 
1351 	case KMERR_BADCACHE:
1352 		printf("buffer freed to wrong cache\n");
1353 		printf("buffer was allocated from %s,\n", cp->cache_name);
1354 		printf("caller attempting free to %s.\n", cparg->cache_name);
1355 		break;
1356 
1357 	case KMERR_BADSIZE:
1358 		printf("bad free: free size (%u) != alloc size (%u)\n",
1359 		    KMEM_SIZE_DECODE(((uint32_t *)btp)[0]),
1360 		    KMEM_SIZE_DECODE(((uint32_t *)btp)[1]));
1361 		break;
1362 
1363 	case KMERR_BADBASE:
1364 		printf("bad free: free address (%p) != alloc address (%p)\n",
1365 		    bufarg, buf);
1366 		break;
1367 	}
1368 
1369 	printf("buffer=%p  bufctl=%p  cache: %s\n",
1370 	    bufarg, (void *)bcp, cparg->cache_name);
1371 
1372 	if (bcp != NULL && (cp->cache_flags & KMF_AUDIT) &&
1373 	    error != KMERR_BADBUFCTL) {
1374 		int d;
1375 		timestruc_t ts;
1376 		kmem_bufctl_audit_t *bcap = (kmem_bufctl_audit_t *)bcp;
1377 
1378 		hrt2ts(kmem_panic_info.kmp_timestamp - bcap->bc_timestamp, &ts);
1379 		printf("previous transaction on buffer %p:\n", buf);
1380 		printf("thread=%p  time=T-%ld.%09ld  slab=%p  cache: %s\n",
1381 		    (void *)bcap->bc_thread, ts.tv_sec, ts.tv_nsec,
1382 		    (void *)sp, cp->cache_name);
1383 		for (d = 0; d < MIN(bcap->bc_depth, KMEM_STACK_DEPTH); d++) {
1384 			ulong_t off;
1385 			char *sym = kobj_getsymname(bcap->bc_stack[d], &off);
1386 			printf("%s+%lx\n", sym ? sym : "?", off);
1387 		}
1388 	}
1389 	if (kmem_panic > 0)
1390 		panic("kernel heap corruption detected");
1391 	if (kmem_panic == 0)
1392 		debug_enter(NULL);
1393 	kmem_logging = 1;	/* resume logging */
1394 }
1395 
1396 static kmem_log_header_t *
kmem_log_init(size_t logsize)1397 kmem_log_init(size_t logsize)
1398 {
1399 	kmem_log_header_t *lhp;
1400 	int nchunks = 4 * max_ncpus;
1401 	size_t lhsize = (size_t)&((kmem_log_header_t *)0)->lh_cpu[max_ncpus];
1402 	int i;
1403 
1404 	/*
1405 	 * Make sure that lhp->lh_cpu[] is nicely aligned
1406 	 * to prevent false sharing of cache lines.
1407 	 */
1408 	lhsize = P2ROUNDUP(lhsize, KMEM_ALIGN);
1409 	lhp = vmem_xalloc(kmem_log_arena, lhsize, 64, P2NPHASE(lhsize, 64), 0,
1410 	    NULL, NULL, VM_SLEEP);
1411 	bzero(lhp, lhsize);
1412 
1413 	mutex_init(&lhp->lh_lock, NULL, MUTEX_DEFAULT, NULL);
1414 	lhp->lh_nchunks = nchunks;
1415 	lhp->lh_chunksize = P2ROUNDUP(logsize / nchunks + 1, PAGESIZE);
1416 	lhp->lh_base = vmem_alloc(kmem_log_arena,
1417 	    lhp->lh_chunksize * nchunks, VM_SLEEP);
1418 	lhp->lh_free = vmem_alloc(kmem_log_arena,
1419 	    nchunks * sizeof (int), VM_SLEEP);
1420 	bzero(lhp->lh_base, lhp->lh_chunksize * nchunks);
1421 
1422 	for (i = 0; i < max_ncpus; i++) {
1423 		kmem_cpu_log_header_t *clhp = &lhp->lh_cpu[i];
1424 		mutex_init(&clhp->clh_lock, NULL, MUTEX_DEFAULT, NULL);
1425 		clhp->clh_chunk = i;
1426 	}
1427 
1428 	for (i = max_ncpus; i < nchunks; i++)
1429 		lhp->lh_free[i] = i;
1430 
1431 	lhp->lh_head = max_ncpus;
1432 	lhp->lh_tail = 0;
1433 
1434 	return (lhp);
1435 }
1436 
1437 static void *
kmem_log_enter(kmem_log_header_t * lhp,void * data,size_t size)1438 kmem_log_enter(kmem_log_header_t *lhp, void *data, size_t size)
1439 {
1440 	void *logspace;
1441 	kmem_cpu_log_header_t *clhp;
1442 
1443 	if (lhp == NULL || kmem_logging == 0 || panicstr)
1444 		return (NULL);
1445 
1446 	clhp = &lhp->lh_cpu[CPU->cpu_seqid];
1447 
1448 	mutex_enter(&clhp->clh_lock);
1449 	clhp->clh_hits++;
1450 	if (size > clhp->clh_avail) {
1451 		mutex_enter(&lhp->lh_lock);
1452 		lhp->lh_hits++;
1453 		lhp->lh_free[lhp->lh_tail] = clhp->clh_chunk;
1454 		lhp->lh_tail = (lhp->lh_tail + 1) % lhp->lh_nchunks;
1455 		clhp->clh_chunk = lhp->lh_free[lhp->lh_head];
1456 		lhp->lh_head = (lhp->lh_head + 1) % lhp->lh_nchunks;
1457 		clhp->clh_current = lhp->lh_base +
1458 		    clhp->clh_chunk * lhp->lh_chunksize;
1459 		clhp->clh_avail = lhp->lh_chunksize;
1460 		if (size > lhp->lh_chunksize)
1461 			size = lhp->lh_chunksize;
1462 		mutex_exit(&lhp->lh_lock);
1463 	}
1464 	logspace = clhp->clh_current;
1465 	clhp->clh_current += size;
1466 	clhp->clh_avail -= size;
1467 	bcopy(data, logspace, size);
1468 	mutex_exit(&clhp->clh_lock);
1469 	return (logspace);
1470 }
1471 
1472 #define	KMEM_AUDIT(lp, cp, bcp)						\
1473 {									\
1474 	kmem_bufctl_audit_t *_bcp = (kmem_bufctl_audit_t *)(bcp);	\
1475 	_bcp->bc_timestamp = gethrtime();				\
1476 	_bcp->bc_thread = curthread;					\
1477 	_bcp->bc_depth = getpcstack(_bcp->bc_stack, KMEM_STACK_DEPTH);	\
1478 	_bcp->bc_lastlog = kmem_log_enter((lp), _bcp, sizeof (*_bcp));	\
1479 }
1480 
1481 static void
kmem_log_event(kmem_log_header_t * lp,kmem_cache_t * cp,kmem_slab_t * sp,void * addr)1482 kmem_log_event(kmem_log_header_t *lp, kmem_cache_t *cp,
1483     kmem_slab_t *sp, void *addr)
1484 {
1485 	kmem_bufctl_audit_t bca;
1486 
1487 	bzero(&bca, sizeof (kmem_bufctl_audit_t));
1488 	bca.bc_addr = addr;
1489 	bca.bc_slab = sp;
1490 	bca.bc_cache = cp;
1491 	KMEM_AUDIT(lp, cp, &bca);
1492 }
1493 
1494 /*
1495  * Create a new slab for cache cp.
1496  */
1497 static kmem_slab_t *
kmem_slab_create(kmem_cache_t * cp,int kmflag)1498 kmem_slab_create(kmem_cache_t *cp, int kmflag)
1499 {
1500 	size_t slabsize = cp->cache_slabsize;
1501 	size_t chunksize = cp->cache_chunksize;
1502 	int cache_flags = cp->cache_flags;
1503 	size_t color, chunks;
1504 	char *buf, *slab;
1505 	kmem_slab_t *sp;
1506 	kmem_bufctl_t *bcp;
1507 	vmem_t *vmp = cp->cache_arena;
1508 
1509 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1510 
1511 	color = cp->cache_color + cp->cache_align;
1512 	if (color > cp->cache_maxcolor)
1513 		color = cp->cache_mincolor;
1514 	cp->cache_color = color;
1515 
1516 	slab = vmem_alloc(vmp, slabsize, kmflag & KM_VMFLAGS);
1517 
1518 	if (slab == NULL)
1519 		goto vmem_alloc_failure;
1520 
1521 	ASSERT(P2PHASE((uintptr_t)slab, vmp->vm_quantum) == 0);
1522 
1523 	/*
1524 	 * Reverify what was already checked in kmem_cache_set_move(), since the
1525 	 * consolidator depends (for correctness) on slabs being initialized
1526 	 * with the 0xbaddcafe memory pattern (setting a low order bit usable by
1527 	 * clients to distinguish uninitialized memory from known objects).
1528 	 */
1529 	ASSERT((cp->cache_move == NULL) || !(cp->cache_cflags & KMC_NOTOUCH));
1530 	if (!(cp->cache_cflags & KMC_NOTOUCH))
1531 		copy_pattern(KMEM_UNINITIALIZED_PATTERN, slab, slabsize);
1532 
1533 	if (cache_flags & KMF_HASH) {
1534 		if ((sp = kmem_cache_alloc(kmem_slab_cache, kmflag)) == NULL)
1535 			goto slab_alloc_failure;
1536 		chunks = (slabsize - color) / chunksize;
1537 	} else {
1538 		sp = KMEM_SLAB(cp, slab);
1539 		chunks = (slabsize - sizeof (kmem_slab_t) - color) / chunksize;
1540 	}
1541 
1542 	sp->slab_cache	= cp;
1543 	sp->slab_head	= NULL;
1544 	sp->slab_refcnt	= 0;
1545 	sp->slab_base	= buf = slab + color;
1546 	sp->slab_chunks	= chunks;
1547 	sp->slab_stuck_offset = (uint32_t)-1;
1548 	sp->slab_later_count = 0;
1549 	sp->slab_flags = 0;
1550 
1551 	ASSERT(chunks > 0);
1552 	while (chunks-- != 0) {
1553 		if (cache_flags & KMF_HASH) {
1554 			bcp = kmem_cache_alloc(cp->cache_bufctl_cache, kmflag);
1555 			if (bcp == NULL)
1556 				goto bufctl_alloc_failure;
1557 			if (cache_flags & KMF_AUDIT) {
1558 				kmem_bufctl_audit_t *bcap =
1559 				    (kmem_bufctl_audit_t *)bcp;
1560 				bzero(bcap, sizeof (kmem_bufctl_audit_t));
1561 				bcap->bc_cache = cp;
1562 			}
1563 			bcp->bc_addr = buf;
1564 			bcp->bc_slab = sp;
1565 		} else {
1566 			bcp = KMEM_BUFCTL(cp, buf);
1567 		}
1568 		if (cache_flags & KMF_BUFTAG) {
1569 			kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1570 			btp->bt_redzone = KMEM_REDZONE_PATTERN;
1571 			btp->bt_bufctl = bcp;
1572 			btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1573 			if (cache_flags & KMF_DEADBEEF) {
1574 				copy_pattern(KMEM_FREE_PATTERN, buf,
1575 				    cp->cache_verify);
1576 			}
1577 		}
1578 		bcp->bc_next = sp->slab_head;
1579 		sp->slab_head = bcp;
1580 		buf += chunksize;
1581 	}
1582 
1583 	kmem_log_event(kmem_slab_log, cp, sp, slab);
1584 
1585 	return (sp);
1586 
1587 bufctl_alloc_failure:
1588 
1589 	while ((bcp = sp->slab_head) != NULL) {
1590 		sp->slab_head = bcp->bc_next;
1591 		kmem_cache_free(cp->cache_bufctl_cache, bcp);
1592 	}
1593 	kmem_cache_free(kmem_slab_cache, sp);
1594 
1595 slab_alloc_failure:
1596 
1597 	vmem_free(vmp, slab, slabsize);
1598 
1599 vmem_alloc_failure:
1600 
1601 	kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1602 	atomic_inc_64(&cp->cache_alloc_fail);
1603 
1604 	return (NULL);
1605 }
1606 
1607 /*
1608  * Destroy a slab.
1609  */
1610 static void
kmem_slab_destroy(kmem_cache_t * cp,kmem_slab_t * sp)1611 kmem_slab_destroy(kmem_cache_t *cp, kmem_slab_t *sp)
1612 {
1613 	vmem_t *vmp = cp->cache_arena;
1614 	void *slab = (void *)P2ALIGN((uintptr_t)sp->slab_base, vmp->vm_quantum);
1615 
1616 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
1617 	ASSERT(sp->slab_refcnt == 0);
1618 
1619 	if (cp->cache_flags & KMF_HASH) {
1620 		kmem_bufctl_t *bcp;
1621 		while ((bcp = sp->slab_head) != NULL) {
1622 			sp->slab_head = bcp->bc_next;
1623 			kmem_cache_free(cp->cache_bufctl_cache, bcp);
1624 		}
1625 		kmem_cache_free(kmem_slab_cache, sp);
1626 	}
1627 	vmem_free(vmp, slab, cp->cache_slabsize);
1628 }
1629 
1630 static void *
kmem_slab_alloc_impl(kmem_cache_t * cp,kmem_slab_t * sp,boolean_t prefill)1631 kmem_slab_alloc_impl(kmem_cache_t *cp, kmem_slab_t *sp, boolean_t prefill)
1632 {
1633 	kmem_bufctl_t *bcp, **hash_bucket;
1634 	void *buf;
1635 	boolean_t new_slab = (sp->slab_refcnt == 0);
1636 
1637 	ASSERT(MUTEX_HELD(&cp->cache_lock));
1638 	/*
1639 	 * kmem_slab_alloc() drops cache_lock when it creates a new slab, so we
1640 	 * can't ASSERT(avl_is_empty(&cp->cache_partial_slabs)) here when the
1641 	 * slab is newly created.
1642 	 */
1643 	ASSERT(new_slab || (KMEM_SLAB_IS_PARTIAL(sp) &&
1644 	    (sp == avl_first(&cp->cache_partial_slabs))));
1645 	ASSERT(sp->slab_cache == cp);
1646 
1647 	cp->cache_slab_alloc++;
1648 	cp->cache_bufslab--;
1649 	sp->slab_refcnt++;
1650 
1651 	bcp = sp->slab_head;
1652 	sp->slab_head = bcp->bc_next;
1653 
1654 	if (cp->cache_flags & KMF_HASH) {
1655 		/*
1656 		 * Add buffer to allocated-address hash table.
1657 		 */
1658 		buf = bcp->bc_addr;
1659 		hash_bucket = KMEM_HASH(cp, buf);
1660 		bcp->bc_next = *hash_bucket;
1661 		*hash_bucket = bcp;
1662 		if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1663 			KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1664 		}
1665 	} else {
1666 		buf = KMEM_BUF(cp, bcp);
1667 	}
1668 
1669 	ASSERT(KMEM_SLAB_MEMBER(sp, buf));
1670 
1671 	if (sp->slab_head == NULL) {
1672 		ASSERT(KMEM_SLAB_IS_ALL_USED(sp));
1673 		if (new_slab) {
1674 			ASSERT(sp->slab_chunks == 1);
1675 		} else {
1676 			ASSERT(sp->slab_chunks > 1); /* the slab was partial */
1677 			avl_remove(&cp->cache_partial_slabs, sp);
1678 			sp->slab_later_count = 0; /* clear history */
1679 			sp->slab_flags &= ~KMEM_SLAB_NOMOVE;
1680 			sp->slab_stuck_offset = (uint32_t)-1;
1681 		}
1682 		list_insert_head(&cp->cache_complete_slabs, sp);
1683 		cp->cache_complete_slab_count++;
1684 		return (buf);
1685 	}
1686 
1687 	ASSERT(KMEM_SLAB_IS_PARTIAL(sp));
1688 	/*
1689 	 * Peek to see if the magazine layer is enabled before
1690 	 * we prefill.  We're not holding the cpu cache lock,
1691 	 * so the peek could be wrong, but there's no harm in it.
1692 	 */
1693 	if (new_slab && prefill && (cp->cache_flags & KMF_PREFILL) &&
1694 	    (KMEM_CPU_CACHE(cp)->cc_magsize != 0))  {
1695 		kmem_slab_prefill(cp, sp);
1696 		return (buf);
1697 	}
1698 
1699 	if (new_slab) {
1700 		avl_add(&cp->cache_partial_slabs, sp);
1701 		return (buf);
1702 	}
1703 
1704 	/*
1705 	 * The slab is now more allocated than it was, so the
1706 	 * order remains unchanged.
1707 	 */
1708 	ASSERT(!avl_update(&cp->cache_partial_slabs, sp));
1709 	return (buf);
1710 }
1711 
1712 /*
1713  * Allocate a raw (unconstructed) buffer from cp's slab layer.
1714  */
1715 static void *
kmem_slab_alloc(kmem_cache_t * cp,int kmflag)1716 kmem_slab_alloc(kmem_cache_t *cp, int kmflag)
1717 {
1718 	kmem_slab_t *sp;
1719 	void *buf;
1720 	boolean_t test_destructor;
1721 
1722 	mutex_enter(&cp->cache_lock);
1723 	test_destructor = (cp->cache_slab_alloc == 0);
1724 	sp = avl_first(&cp->cache_partial_slabs);
1725 	if (sp == NULL) {
1726 		ASSERT(cp->cache_bufslab == 0);
1727 
1728 		/*
1729 		 * The freelist is empty.  Create a new slab.
1730 		 */
1731 		mutex_exit(&cp->cache_lock);
1732 		if ((sp = kmem_slab_create(cp, kmflag)) == NULL) {
1733 			return (NULL);
1734 		}
1735 		mutex_enter(&cp->cache_lock);
1736 		cp->cache_slab_create++;
1737 		if ((cp->cache_buftotal += sp->slab_chunks) > cp->cache_bufmax)
1738 			cp->cache_bufmax = cp->cache_buftotal;
1739 		cp->cache_bufslab += sp->slab_chunks;
1740 	}
1741 
1742 	buf = kmem_slab_alloc_impl(cp, sp, B_TRUE);
1743 	ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1744 	    (cp->cache_complete_slab_count +
1745 	    avl_numnodes(&cp->cache_partial_slabs) +
1746 	    (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1747 	mutex_exit(&cp->cache_lock);
1748 
1749 	if (test_destructor && cp->cache_destructor != NULL) {
1750 		/*
1751 		 * On the first kmem_slab_alloc(), assert that it is valid to
1752 		 * call the destructor on a newly constructed object without any
1753 		 * client involvement.
1754 		 */
1755 		if ((cp->cache_constructor == NULL) ||
1756 		    cp->cache_constructor(buf, cp->cache_private,
1757 		    kmflag) == 0) {
1758 			cp->cache_destructor(buf, cp->cache_private);
1759 		}
1760 		copy_pattern(KMEM_UNINITIALIZED_PATTERN, buf,
1761 		    cp->cache_bufsize);
1762 		if (cp->cache_flags & KMF_DEADBEEF) {
1763 			copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1764 		}
1765 	}
1766 
1767 	return (buf);
1768 }
1769 
1770 static void kmem_slab_move_yes(kmem_cache_t *, kmem_slab_t *, void *);
1771 
1772 /*
1773  * Free a raw (unconstructed) buffer to cp's slab layer.
1774  */
1775 static void
kmem_slab_free(kmem_cache_t * cp,void * buf)1776 kmem_slab_free(kmem_cache_t *cp, void *buf)
1777 {
1778 	kmem_slab_t *sp;
1779 	kmem_bufctl_t *bcp, **prev_bcpp;
1780 
1781 	ASSERT(buf != NULL);
1782 
1783 	mutex_enter(&cp->cache_lock);
1784 	cp->cache_slab_free++;
1785 
1786 	if (cp->cache_flags & KMF_HASH) {
1787 		/*
1788 		 * Look up buffer in allocated-address hash table.
1789 		 */
1790 		prev_bcpp = KMEM_HASH(cp, buf);
1791 		while ((bcp = *prev_bcpp) != NULL) {
1792 			if (bcp->bc_addr == buf) {
1793 				*prev_bcpp = bcp->bc_next;
1794 				sp = bcp->bc_slab;
1795 				break;
1796 			}
1797 			cp->cache_lookup_depth++;
1798 			prev_bcpp = &bcp->bc_next;
1799 		}
1800 	} else {
1801 		bcp = KMEM_BUFCTL(cp, buf);
1802 		sp = KMEM_SLAB(cp, buf);
1803 	}
1804 
1805 	if (bcp == NULL || sp->slab_cache != cp || !KMEM_SLAB_MEMBER(sp, buf)) {
1806 		mutex_exit(&cp->cache_lock);
1807 		kmem_error(KMERR_BADADDR, cp, buf);
1808 		return;
1809 	}
1810 
1811 	if (KMEM_SLAB_OFFSET(sp, buf) == sp->slab_stuck_offset) {
1812 		/*
1813 		 * If this is the buffer that prevented the consolidator from
1814 		 * clearing the slab, we can reset the slab flags now that the
1815 		 * buffer is freed. (It makes sense to do this in
1816 		 * kmem_cache_free(), where the client gives up ownership of the
1817 		 * buffer, but on the hot path the test is too expensive.)
1818 		 */
1819 		kmem_slab_move_yes(cp, sp, buf);
1820 	}
1821 
1822 	if ((cp->cache_flags & (KMF_AUDIT | KMF_BUFTAG)) == KMF_AUDIT) {
1823 		if (cp->cache_flags & KMF_CONTENTS)
1824 			((kmem_bufctl_audit_t *)bcp)->bc_contents =
1825 			    kmem_log_enter(kmem_content_log, buf,
1826 			    cp->cache_contents);
1827 		KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1828 	}
1829 
1830 	bcp->bc_next = sp->slab_head;
1831 	sp->slab_head = bcp;
1832 
1833 	cp->cache_bufslab++;
1834 	ASSERT(sp->slab_refcnt >= 1);
1835 
1836 	if (--sp->slab_refcnt == 0) {
1837 		/*
1838 		 * There are no outstanding allocations from this slab,
1839 		 * so we can reclaim the memory.
1840 		 */
1841 		if (sp->slab_chunks == 1) {
1842 			list_remove(&cp->cache_complete_slabs, sp);
1843 			cp->cache_complete_slab_count--;
1844 		} else {
1845 			avl_remove(&cp->cache_partial_slabs, sp);
1846 		}
1847 
1848 		cp->cache_buftotal -= sp->slab_chunks;
1849 		cp->cache_bufslab -= sp->slab_chunks;
1850 		/*
1851 		 * Defer releasing the slab to the virtual memory subsystem
1852 		 * while there is a pending move callback, since we guarantee
1853 		 * that buffers passed to the move callback have only been
1854 		 * touched by kmem or by the client itself. Since the memory
1855 		 * patterns baddcafe (uninitialized) and deadbeef (freed) both
1856 		 * set at least one of the two lowest order bits, the client can
1857 		 * test those bits in the move callback to determine whether or
1858 		 * not it knows about the buffer (assuming that the client also
1859 		 * sets one of those low order bits whenever it frees a buffer).
1860 		 */
1861 		if (cp->cache_defrag == NULL ||
1862 		    (avl_is_empty(&cp->cache_defrag->kmd_moves_pending) &&
1863 		    !(sp->slab_flags & KMEM_SLAB_MOVE_PENDING))) {
1864 			cp->cache_slab_destroy++;
1865 			mutex_exit(&cp->cache_lock);
1866 			kmem_slab_destroy(cp, sp);
1867 		} else {
1868 			list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
1869 			/*
1870 			 * Slabs are inserted at both ends of the deadlist to
1871 			 * distinguish between slabs freed while move callbacks
1872 			 * are pending (list head) and a slab freed while the
1873 			 * lock is dropped in kmem_move_buffers() (list tail) so
1874 			 * that in both cases slab_destroy() is called from the
1875 			 * right context.
1876 			 */
1877 			if (sp->slab_flags & KMEM_SLAB_MOVE_PENDING) {
1878 				list_insert_tail(deadlist, sp);
1879 			} else {
1880 				list_insert_head(deadlist, sp);
1881 			}
1882 			cp->cache_defrag->kmd_deadcount++;
1883 			mutex_exit(&cp->cache_lock);
1884 		}
1885 		return;
1886 	}
1887 
1888 	if (bcp->bc_next == NULL) {
1889 		/* Transition the slab from completely allocated to partial. */
1890 		ASSERT(sp->slab_refcnt == (sp->slab_chunks - 1));
1891 		ASSERT(sp->slab_chunks > 1);
1892 		list_remove(&cp->cache_complete_slabs, sp);
1893 		cp->cache_complete_slab_count--;
1894 		avl_add(&cp->cache_partial_slabs, sp);
1895 	} else {
1896 		(void) avl_update_gt(&cp->cache_partial_slabs, sp);
1897 	}
1898 
1899 	ASSERT((cp->cache_slab_create - cp->cache_slab_destroy) ==
1900 	    (cp->cache_complete_slab_count +
1901 	    avl_numnodes(&cp->cache_partial_slabs) +
1902 	    (cp->cache_defrag == NULL ? 0 : cp->cache_defrag->kmd_deadcount)));
1903 	mutex_exit(&cp->cache_lock);
1904 }
1905 
1906 /*
1907  * Return -1 if kmem_error, 1 if constructor fails, 0 if successful.
1908  */
1909 static int
kmem_cache_alloc_debug(kmem_cache_t * cp,void * buf,int kmflag,int construct,caddr_t caller)1910 kmem_cache_alloc_debug(kmem_cache_t *cp, void *buf, int kmflag, int construct,
1911     caddr_t caller)
1912 {
1913 	kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1914 	kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
1915 	uint32_t mtbf;
1916 
1917 	if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
1918 		kmem_error(KMERR_BADBUFTAG, cp, buf);
1919 		return (-1);
1920 	}
1921 
1922 	btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_ALLOC;
1923 
1924 	if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
1925 		kmem_error(KMERR_BADBUFCTL, cp, buf);
1926 		return (-1);
1927 	}
1928 
1929 	if (cp->cache_flags & KMF_DEADBEEF) {
1930 		if (!construct && (cp->cache_flags & KMF_LITE)) {
1931 			if (*(uint64_t *)buf != KMEM_FREE_PATTERN) {
1932 				kmem_error(KMERR_MODIFIED, cp, buf);
1933 				return (-1);
1934 			}
1935 			if (cp->cache_constructor != NULL)
1936 				*(uint64_t *)buf = btp->bt_redzone;
1937 			else
1938 				*(uint64_t *)buf = KMEM_UNINITIALIZED_PATTERN;
1939 		} else {
1940 			construct = 1;
1941 			if (verify_and_copy_pattern(KMEM_FREE_PATTERN,
1942 			    KMEM_UNINITIALIZED_PATTERN, buf,
1943 			    cp->cache_verify)) {
1944 				kmem_error(KMERR_MODIFIED, cp, buf);
1945 				return (-1);
1946 			}
1947 		}
1948 	}
1949 	btp->bt_redzone = KMEM_REDZONE_PATTERN;
1950 
1951 	if ((mtbf = kmem_mtbf | cp->cache_mtbf) != 0 &&
1952 	    gethrtime() % mtbf == 0 &&
1953 	    (kmflag & (KM_NOSLEEP | KM_PANIC)) == KM_NOSLEEP) {
1954 		kmem_log_event(kmem_failure_log, cp, NULL, NULL);
1955 		if (!construct && cp->cache_destructor != NULL)
1956 			cp->cache_destructor(buf, cp->cache_private);
1957 	} else {
1958 		mtbf = 0;
1959 	}
1960 
1961 	if (mtbf || (construct && cp->cache_constructor != NULL &&
1962 	    cp->cache_constructor(buf, cp->cache_private, kmflag) != 0)) {
1963 		atomic_inc_64(&cp->cache_alloc_fail);
1964 		btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
1965 		if (cp->cache_flags & KMF_DEADBEEF)
1966 			copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
1967 		kmem_slab_free(cp, buf);
1968 		return (1);
1969 	}
1970 
1971 	if (cp->cache_flags & KMF_AUDIT) {
1972 		KMEM_AUDIT(kmem_transaction_log, cp, bcp);
1973 	}
1974 
1975 	if ((cp->cache_flags & KMF_LITE) &&
1976 	    !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
1977 		KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
1978 	}
1979 
1980 	return (0);
1981 }
1982 
1983 static int
kmem_cache_free_debug(kmem_cache_t * cp,void * buf,caddr_t caller)1984 kmem_cache_free_debug(kmem_cache_t *cp, void *buf, caddr_t caller)
1985 {
1986 	kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
1987 	kmem_bufctl_audit_t *bcp = (kmem_bufctl_audit_t *)btp->bt_bufctl;
1988 	kmem_slab_t *sp;
1989 
1990 	if (btp->bt_bxstat != ((intptr_t)bcp ^ KMEM_BUFTAG_ALLOC)) {
1991 		if (btp->bt_bxstat == ((intptr_t)bcp ^ KMEM_BUFTAG_FREE)) {
1992 			kmem_error(KMERR_DUPFREE, cp, buf);
1993 			return (-1);
1994 		}
1995 		sp = kmem_findslab(cp, buf);
1996 		if (sp == NULL || sp->slab_cache != cp)
1997 			kmem_error(KMERR_BADADDR, cp, buf);
1998 		else
1999 			kmem_error(KMERR_REDZONE, cp, buf);
2000 		return (-1);
2001 	}
2002 
2003 	btp->bt_bxstat = (intptr_t)bcp ^ KMEM_BUFTAG_FREE;
2004 
2005 	if ((cp->cache_flags & KMF_HASH) && bcp->bc_addr != buf) {
2006 		kmem_error(KMERR_BADBUFCTL, cp, buf);
2007 		return (-1);
2008 	}
2009 
2010 	if (btp->bt_redzone != KMEM_REDZONE_PATTERN) {
2011 		kmem_error(KMERR_REDZONE, cp, buf);
2012 		return (-1);
2013 	}
2014 
2015 	if (cp->cache_flags & KMF_AUDIT) {
2016 		if (cp->cache_flags & KMF_CONTENTS)
2017 			bcp->bc_contents = kmem_log_enter(kmem_content_log,
2018 			    buf, cp->cache_contents);
2019 		KMEM_AUDIT(kmem_transaction_log, cp, bcp);
2020 	}
2021 
2022 	if ((cp->cache_flags & KMF_LITE) &&
2023 	    !(cp->cache_cflags & KMC_KMEM_ALLOC)) {
2024 		KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller);
2025 	}
2026 
2027 	if (cp->cache_flags & KMF_DEADBEEF) {
2028 		if (cp->cache_flags & KMF_LITE)
2029 			btp->bt_redzone = *(uint64_t *)buf;
2030 		else if (cp->cache_destructor != NULL)
2031 			cp->cache_destructor(buf, cp->cache_private);
2032 
2033 		copy_pattern(KMEM_FREE_PATTERN, buf, cp->cache_verify);
2034 	}
2035 
2036 	return (0);
2037 }
2038 
2039 /*
2040  * Free each object in magazine mp to cp's slab layer, and free mp itself.
2041  */
2042 static void
kmem_magazine_destroy(kmem_cache_t * cp,kmem_magazine_t * mp,int nrounds)2043 kmem_magazine_destroy(kmem_cache_t *cp, kmem_magazine_t *mp, int nrounds)
2044 {
2045 	int round;
2046 
2047 	ASSERT(!list_link_active(&cp->cache_link) ||
2048 	    taskq_member(kmem_taskq, curthread));
2049 
2050 	for (round = 0; round < nrounds; round++) {
2051 		void *buf = mp->mag_round[round];
2052 
2053 		if (cp->cache_flags & KMF_DEADBEEF) {
2054 			if (verify_pattern(KMEM_FREE_PATTERN, buf,
2055 			    cp->cache_verify) != NULL) {
2056 				kmem_error(KMERR_MODIFIED, cp, buf);
2057 				continue;
2058 			}
2059 			if ((cp->cache_flags & KMF_LITE) &&
2060 			    cp->cache_destructor != NULL) {
2061 				kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2062 				*(uint64_t *)buf = btp->bt_redzone;
2063 				cp->cache_destructor(buf, cp->cache_private);
2064 				*(uint64_t *)buf = KMEM_FREE_PATTERN;
2065 			}
2066 		} else if (cp->cache_destructor != NULL) {
2067 			cp->cache_destructor(buf, cp->cache_private);
2068 		}
2069 
2070 		kmem_slab_free(cp, buf);
2071 	}
2072 	ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2073 	kmem_cache_free(cp->cache_magtype->mt_cache, mp);
2074 }
2075 
2076 /*
2077  * Allocate a magazine from the depot.
2078  */
2079 static kmem_magazine_t *
kmem_depot_alloc(kmem_cache_t * cp,kmem_maglist_t * mlp)2080 kmem_depot_alloc(kmem_cache_t *cp, kmem_maglist_t *mlp)
2081 {
2082 	kmem_magazine_t *mp;
2083 
2084 	/*
2085 	 * If we can't get the depot lock without contention,
2086 	 * update our contention count.  We use the depot
2087 	 * contention rate to determine whether we need to
2088 	 * increase the magazine size for better scalability.
2089 	 */
2090 	if (!mutex_tryenter(&cp->cache_depot_lock)) {
2091 		mutex_enter(&cp->cache_depot_lock);
2092 		cp->cache_depot_contention++;
2093 	}
2094 
2095 	if ((mp = mlp->ml_list) != NULL) {
2096 		ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2097 		mlp->ml_list = mp->mag_next;
2098 		if (--mlp->ml_total < mlp->ml_min)
2099 			mlp->ml_min = mlp->ml_total;
2100 		mlp->ml_alloc++;
2101 	}
2102 
2103 	mutex_exit(&cp->cache_depot_lock);
2104 
2105 	return (mp);
2106 }
2107 
2108 /*
2109  * Free a magazine to the depot.
2110  */
2111 static void
kmem_depot_free(kmem_cache_t * cp,kmem_maglist_t * mlp,kmem_magazine_t * mp)2112 kmem_depot_free(kmem_cache_t *cp, kmem_maglist_t *mlp, kmem_magazine_t *mp)
2113 {
2114 	mutex_enter(&cp->cache_depot_lock);
2115 	ASSERT(KMEM_MAGAZINE_VALID(cp, mp));
2116 	mp->mag_next = mlp->ml_list;
2117 	mlp->ml_list = mp;
2118 	mlp->ml_total++;
2119 	mutex_exit(&cp->cache_depot_lock);
2120 }
2121 
2122 /*
2123  * Update the working set statistics for cp's depot.
2124  */
2125 static void
kmem_depot_ws_update(kmem_cache_t * cp)2126 kmem_depot_ws_update(kmem_cache_t *cp)
2127 {
2128 	mutex_enter(&cp->cache_depot_lock);
2129 	cp->cache_full.ml_reaplimit = cp->cache_full.ml_min;
2130 	cp->cache_full.ml_min = cp->cache_full.ml_total;
2131 	cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_min;
2132 	cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2133 	mutex_exit(&cp->cache_depot_lock);
2134 }
2135 
2136 /*
2137  * Set the working set statistics for cp's depot to zero.  (Everything is
2138  * eligible for reaping.)
2139  */
2140 static void
kmem_depot_ws_zero(kmem_cache_t * cp)2141 kmem_depot_ws_zero(kmem_cache_t *cp)
2142 {
2143 	mutex_enter(&cp->cache_depot_lock);
2144 	cp->cache_full.ml_reaplimit = cp->cache_full.ml_total;
2145 	cp->cache_full.ml_min = cp->cache_full.ml_total;
2146 	cp->cache_empty.ml_reaplimit = cp->cache_empty.ml_total;
2147 	cp->cache_empty.ml_min = cp->cache_empty.ml_total;
2148 	mutex_exit(&cp->cache_depot_lock);
2149 }
2150 
2151 /*
2152  * The number of bytes to reap before we call kpreempt(). The default (1MB)
2153  * causes us to preempt reaping up to hundreds of times per second. Using a
2154  * larger value (1GB) causes this to have virtually no effect.
2155  */
2156 size_t kmem_reap_preempt_bytes = 1024 * 1024;
2157 
2158 /*
2159  * Reap all magazines that have fallen out of the depot's working set.
2160  */
2161 static void
kmem_depot_ws_reap(kmem_cache_t * cp)2162 kmem_depot_ws_reap(kmem_cache_t *cp)
2163 {
2164 	size_t bytes = 0;
2165 	long reap;
2166 	kmem_magazine_t *mp;
2167 
2168 	ASSERT(!list_link_active(&cp->cache_link) ||
2169 	    taskq_member(kmem_taskq, curthread));
2170 
2171 	reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
2172 	while (reap-- &&
2173 	    (mp = kmem_depot_alloc(cp, &cp->cache_full)) != NULL) {
2174 		kmem_magazine_destroy(cp, mp, cp->cache_magtype->mt_magsize);
2175 		bytes += cp->cache_magtype->mt_magsize * cp->cache_bufsize;
2176 		if (bytes > kmem_reap_preempt_bytes) {
2177 			kpreempt(KPREEMPT_SYNC);
2178 			bytes = 0;
2179 		}
2180 	}
2181 
2182 	reap = MIN(cp->cache_empty.ml_reaplimit, cp->cache_empty.ml_min);
2183 	while (reap-- &&
2184 	    (mp = kmem_depot_alloc(cp, &cp->cache_empty)) != NULL) {
2185 		kmem_magazine_destroy(cp, mp, 0);
2186 		bytes += cp->cache_magtype->mt_magsize * cp->cache_bufsize;
2187 		if (bytes > kmem_reap_preempt_bytes) {
2188 			kpreempt(KPREEMPT_SYNC);
2189 			bytes = 0;
2190 		}
2191 	}
2192 }
2193 
2194 static void
kmem_cpu_reload(kmem_cpu_cache_t * ccp,kmem_magazine_t * mp,int rounds)2195 kmem_cpu_reload(kmem_cpu_cache_t *ccp, kmem_magazine_t *mp, int rounds)
2196 {
2197 	ASSERT((ccp->cc_loaded == NULL && ccp->cc_rounds == -1) ||
2198 	    (ccp->cc_loaded && ccp->cc_rounds + rounds == ccp->cc_magsize));
2199 	ASSERT(ccp->cc_magsize > 0);
2200 
2201 	ccp->cc_ploaded = ccp->cc_loaded;
2202 	ccp->cc_prounds = ccp->cc_rounds;
2203 	ccp->cc_loaded = mp;
2204 	ccp->cc_rounds = rounds;
2205 }
2206 
2207 /*
2208  * Intercept kmem alloc/free calls during crash dump in order to avoid
2209  * changing kmem state while memory is being saved to the dump device.
2210  * Otherwise, ::kmem_verify will report "corrupt buffers".  Note that
2211  * there are no locks because only one CPU calls kmem during a crash
2212  * dump. To enable this feature, first create the associated vmem
2213  * arena with VMC_DUMPSAFE.
2214  */
2215 static void *kmem_dump_start;	/* start of pre-reserved heap */
2216 static void *kmem_dump_end;	/* end of heap area */
2217 static void *kmem_dump_curr;	/* current free heap pointer */
2218 static size_t kmem_dump_size;	/* size of heap area */
2219 
2220 /* append to each buf created in the pre-reserved heap */
2221 typedef struct kmem_dumpctl {
2222 	void	*kdc_next;	/* cache dump free list linkage */
2223 } kmem_dumpctl_t;
2224 
2225 #define	KMEM_DUMPCTL(cp, buf)	\
2226 	((kmem_dumpctl_t *)P2ROUNDUP((uintptr_t)(buf) + (cp)->cache_bufsize, \
2227 	    sizeof (void *)))
2228 
2229 /* set non zero for full report */
2230 uint_t kmem_dump_verbose = 0;
2231 
2232 /* stats for overize heap */
2233 uint_t kmem_dump_oversize_allocs = 0;
2234 uint_t kmem_dump_oversize_max = 0;
2235 
2236 static void
kmem_dumppr(char ** pp,char * e,const char * format,...)2237 kmem_dumppr(char **pp, char *e, const char *format, ...)
2238 {
2239 	char *p = *pp;
2240 
2241 	if (p < e) {
2242 		int n;
2243 		va_list ap;
2244 
2245 		va_start(ap, format);
2246 		n = vsnprintf(p, e - p, format, ap);
2247 		va_end(ap);
2248 		*pp = p + n;
2249 	}
2250 }
2251 
2252 /*
2253  * Called when dumpadm(1M) configures dump parameters.
2254  */
2255 void
kmem_dump_init(size_t size)2256 kmem_dump_init(size_t size)
2257 {
2258 	/* Our caller ensures size is always set. */
2259 	ASSERT3U(size, >, 0);
2260 
2261 	if (kmem_dump_start != NULL)
2262 		kmem_free(kmem_dump_start, kmem_dump_size);
2263 
2264 	kmem_dump_start = kmem_alloc(size, KM_SLEEP);
2265 	kmem_dump_size = size;
2266 	kmem_dump_curr = kmem_dump_start;
2267 	kmem_dump_end = (void *)((char *)kmem_dump_start + size);
2268 	copy_pattern(KMEM_UNINITIALIZED_PATTERN, kmem_dump_start, size);
2269 }
2270 
2271 /*
2272  * Set flag for each kmem_cache_t if is safe to use alternate dump
2273  * memory. Called just before panic crash dump starts. Set the flag
2274  * for the calling CPU.
2275  */
2276 void
kmem_dump_begin(void)2277 kmem_dump_begin(void)
2278 {
2279 	kmem_cache_t *cp;
2280 
2281 	ASSERT(panicstr != NULL);
2282 
2283 	for (cp = list_head(&kmem_caches); cp != NULL;
2284 	    cp = list_next(&kmem_caches, cp)) {
2285 		kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2286 
2287 		if (cp->cache_arena->vm_cflags & VMC_DUMPSAFE) {
2288 			cp->cache_flags |= KMF_DUMPDIVERT;
2289 			ccp->cc_flags |= KMF_DUMPDIVERT;
2290 			ccp->cc_dump_rounds = ccp->cc_rounds;
2291 			ccp->cc_dump_prounds = ccp->cc_prounds;
2292 			ccp->cc_rounds = ccp->cc_prounds = -1;
2293 		} else {
2294 			cp->cache_flags |= KMF_DUMPUNSAFE;
2295 			ccp->cc_flags |= KMF_DUMPUNSAFE;
2296 		}
2297 	}
2298 }
2299 
2300 /*
2301  * finished dump intercept
2302  * print any warnings on the console
2303  * return verbose information to dumpsys() in the given buffer
2304  */
2305 size_t
kmem_dump_finish(char * buf,size_t size)2306 kmem_dump_finish(char *buf, size_t size)
2307 {
2308 	int percent = 0;
2309 	size_t used;
2310 	char *e = buf + size;
2311 	char *p = buf;
2312 
2313 	if (kmem_dump_curr == kmem_dump_end) {
2314 		cmn_err(CE_WARN, "exceeded kmem_dump space of %lu "
2315 		    "bytes: kmem state in dump may be inconsistent",
2316 		    kmem_dump_size);
2317 	}
2318 
2319 	if (kmem_dump_verbose == 0)
2320 		return (0);
2321 
2322 	used = (char *)kmem_dump_curr - (char *)kmem_dump_start;
2323 	percent = (used * 100) / kmem_dump_size;
2324 
2325 	kmem_dumppr(&p, e, "%% heap used,%d\n", percent);
2326 	kmem_dumppr(&p, e, "used bytes,%ld\n", used);
2327 	kmem_dumppr(&p, e, "heap size,%ld\n", kmem_dump_size);
2328 	kmem_dumppr(&p, e, "Oversize allocs,%d\n",
2329 	    kmem_dump_oversize_allocs);
2330 	kmem_dumppr(&p, e, "Oversize max size,%ld\n",
2331 	    kmem_dump_oversize_max);
2332 
2333 	/* return buffer size used */
2334 	if (p < e)
2335 		bzero(p, e - p);
2336 	return (p - buf);
2337 }
2338 
2339 /*
2340  * Allocate a constructed object from alternate dump memory.
2341  */
2342 void *
kmem_cache_alloc_dump(kmem_cache_t * cp,int kmflag)2343 kmem_cache_alloc_dump(kmem_cache_t *cp, int kmflag)
2344 {
2345 	void *buf;
2346 	void *curr;
2347 	char *bufend;
2348 
2349 	/* return a constructed object */
2350 	if ((buf = cp->cache_dump.kd_freelist) != NULL) {
2351 		cp->cache_dump.kd_freelist = KMEM_DUMPCTL(cp, buf)->kdc_next;
2352 		return (buf);
2353 	}
2354 
2355 	/* create a new constructed object */
2356 	curr = kmem_dump_curr;
2357 	buf = (void *)P2ROUNDUP((uintptr_t)curr, cp->cache_align);
2358 	bufend = (char *)KMEM_DUMPCTL(cp, buf) + sizeof (kmem_dumpctl_t);
2359 
2360 	/* hat layer objects cannot cross a page boundary */
2361 	if (cp->cache_align < PAGESIZE) {
2362 		char *page = (char *)P2ROUNDUP((uintptr_t)buf, PAGESIZE);
2363 		if (bufend > page) {
2364 			bufend += page - (char *)buf;
2365 			buf = (void *)page;
2366 		}
2367 	}
2368 
2369 	/* fall back to normal alloc if reserved area is used up */
2370 	if (bufend > (char *)kmem_dump_end) {
2371 		kmem_dump_curr = kmem_dump_end;
2372 		cp->cache_dump.kd_alloc_fails++;
2373 		return (NULL);
2374 	}
2375 
2376 	/*
2377 	 * Must advance curr pointer before calling a constructor that
2378 	 * may also allocate memory.
2379 	 */
2380 	kmem_dump_curr = bufend;
2381 
2382 	/* run constructor */
2383 	if (cp->cache_constructor != NULL &&
2384 	    cp->cache_constructor(buf, cp->cache_private, kmflag)
2385 	    != 0) {
2386 #ifdef DEBUG
2387 		printf("name='%s' cache=0x%p: kmem cache constructor failed\n",
2388 		    cp->cache_name, (void *)cp);
2389 #endif
2390 		/* reset curr pointer iff no allocs were done */
2391 		if (kmem_dump_curr == bufend)
2392 			kmem_dump_curr = curr;
2393 
2394 		cp->cache_dump.kd_alloc_fails++;
2395 		/* fall back to normal alloc if the constructor fails */
2396 		return (NULL);
2397 	}
2398 
2399 	return (buf);
2400 }
2401 
2402 /*
2403  * Free a constructed object in alternate dump memory.
2404  */
2405 int
kmem_cache_free_dump(kmem_cache_t * cp,void * buf)2406 kmem_cache_free_dump(kmem_cache_t *cp, void *buf)
2407 {
2408 	/* save constructed buffers for next time */
2409 	if ((char *)buf >= (char *)kmem_dump_start &&
2410 	    (char *)buf < (char *)kmem_dump_end) {
2411 		KMEM_DUMPCTL(cp, buf)->kdc_next = cp->cache_dump.kd_freelist;
2412 		cp->cache_dump.kd_freelist = buf;
2413 		return (0);
2414 	}
2415 
2416 	/* just drop buffers that were allocated before dump started */
2417 	if (kmem_dump_curr < kmem_dump_end)
2418 		return (0);
2419 
2420 	/* fall back to normal free if reserved area is used up */
2421 	return (1);
2422 }
2423 
2424 /*
2425  * Allocate a constructed object from cache cp.
2426  */
2427 void *
kmem_cache_alloc(kmem_cache_t * cp,int kmflag)2428 kmem_cache_alloc(kmem_cache_t *cp, int kmflag)
2429 {
2430 	kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2431 	kmem_magazine_t *fmp;
2432 	void *buf;
2433 
2434 	mutex_enter(&ccp->cc_lock);
2435 	for (;;) {
2436 		/*
2437 		 * If there's an object available in the current CPU's
2438 		 * loaded magazine, just take it and return.
2439 		 */
2440 		if (ccp->cc_rounds > 0) {
2441 			buf = ccp->cc_loaded->mag_round[--ccp->cc_rounds];
2442 			ccp->cc_alloc++;
2443 			mutex_exit(&ccp->cc_lock);
2444 			if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPUNSAFE)) {
2445 				if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2446 					ASSERT(!(ccp->cc_flags &
2447 					    KMF_DUMPDIVERT));
2448 					cp->cache_dump.kd_unsafe++;
2449 				}
2450 				if ((ccp->cc_flags & KMF_BUFTAG) &&
2451 				    kmem_cache_alloc_debug(cp, buf, kmflag, 0,
2452 				    caller()) != 0) {
2453 					if (kmflag & KM_NOSLEEP)
2454 						return (NULL);
2455 					mutex_enter(&ccp->cc_lock);
2456 					continue;
2457 				}
2458 			}
2459 			return (buf);
2460 		}
2461 
2462 		/*
2463 		 * The loaded magazine is empty.  If the previously loaded
2464 		 * magazine was full, exchange them and try again.
2465 		 */
2466 		if (ccp->cc_prounds > 0) {
2467 			kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2468 			continue;
2469 		}
2470 
2471 		/*
2472 		 * Return an alternate buffer at dump time to preserve
2473 		 * the heap.
2474 		 */
2475 		if (ccp->cc_flags & (KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2476 			if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2477 				ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2478 				/* log it so that we can warn about it */
2479 				cp->cache_dump.kd_unsafe++;
2480 			} else {
2481 				if ((buf = kmem_cache_alloc_dump(cp, kmflag)) !=
2482 				    NULL) {
2483 					mutex_exit(&ccp->cc_lock);
2484 					return (buf);
2485 				}
2486 				break;		/* fall back to slab layer */
2487 			}
2488 		}
2489 
2490 		/*
2491 		 * If the magazine layer is disabled, break out now.
2492 		 */
2493 		if (ccp->cc_magsize == 0)
2494 			break;
2495 
2496 		/*
2497 		 * Try to get a full magazine from the depot.
2498 		 */
2499 		fmp = kmem_depot_alloc(cp, &cp->cache_full);
2500 		if (fmp != NULL) {
2501 			if (ccp->cc_ploaded != NULL)
2502 				kmem_depot_free(cp, &cp->cache_empty,
2503 				    ccp->cc_ploaded);
2504 			kmem_cpu_reload(ccp, fmp, ccp->cc_magsize);
2505 			continue;
2506 		}
2507 
2508 		/*
2509 		 * There are no full magazines in the depot,
2510 		 * so fall through to the slab layer.
2511 		 */
2512 		break;
2513 	}
2514 	mutex_exit(&ccp->cc_lock);
2515 
2516 	/*
2517 	 * We couldn't allocate a constructed object from the magazine layer,
2518 	 * so get a raw buffer from the slab layer and apply its constructor.
2519 	 */
2520 	buf = kmem_slab_alloc(cp, kmflag);
2521 
2522 	if (buf == NULL)
2523 		return (NULL);
2524 
2525 	if (cp->cache_flags & KMF_BUFTAG) {
2526 		/*
2527 		 * Make kmem_cache_alloc_debug() apply the constructor for us.
2528 		 */
2529 		int rc = kmem_cache_alloc_debug(cp, buf, kmflag, 1, caller());
2530 		if (rc != 0) {
2531 			if (kmflag & KM_NOSLEEP)
2532 				return (NULL);
2533 			/*
2534 			 * kmem_cache_alloc_debug() detected corruption
2535 			 * but didn't panic (kmem_panic <= 0). We should not be
2536 			 * here because the constructor failed (indicated by a
2537 			 * return code of 1). Try again.
2538 			 */
2539 			ASSERT(rc == -1);
2540 			return (kmem_cache_alloc(cp, kmflag));
2541 		}
2542 		return (buf);
2543 	}
2544 
2545 	if (cp->cache_constructor != NULL &&
2546 	    cp->cache_constructor(buf, cp->cache_private, kmflag) != 0) {
2547 		atomic_inc_64(&cp->cache_alloc_fail);
2548 		kmem_slab_free(cp, buf);
2549 		return (NULL);
2550 	}
2551 
2552 	return (buf);
2553 }
2554 
2555 /*
2556  * The freed argument tells whether or not kmem_cache_free_debug() has already
2557  * been called so that we can avoid the duplicate free error. For example, a
2558  * buffer on a magazine has already been freed by the client but is still
2559  * constructed.
2560  */
2561 static void
kmem_slab_free_constructed(kmem_cache_t * cp,void * buf,boolean_t freed)2562 kmem_slab_free_constructed(kmem_cache_t *cp, void *buf, boolean_t freed)
2563 {
2564 	if (!freed && (cp->cache_flags & KMF_BUFTAG))
2565 		if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2566 			return;
2567 
2568 	/*
2569 	 * Note that if KMF_DEADBEEF is in effect and KMF_LITE is not,
2570 	 * kmem_cache_free_debug() will have already applied the destructor.
2571 	 */
2572 	if ((cp->cache_flags & (KMF_DEADBEEF | KMF_LITE)) != KMF_DEADBEEF &&
2573 	    cp->cache_destructor != NULL) {
2574 		if (cp->cache_flags & KMF_DEADBEEF) {	/* KMF_LITE implied */
2575 			kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2576 			*(uint64_t *)buf = btp->bt_redzone;
2577 			cp->cache_destructor(buf, cp->cache_private);
2578 			*(uint64_t *)buf = KMEM_FREE_PATTERN;
2579 		} else {
2580 			cp->cache_destructor(buf, cp->cache_private);
2581 		}
2582 	}
2583 
2584 	kmem_slab_free(cp, buf);
2585 }
2586 
2587 /*
2588  * Used when there's no room to free a buffer to the per-CPU cache.
2589  * Drops and re-acquires &ccp->cc_lock, and returns non-zero if the
2590  * caller should try freeing to the per-CPU cache again.
2591  * Note that we don't directly install the magazine in the cpu cache,
2592  * since its state may have changed wildly while the lock was dropped.
2593  */
2594 static int
kmem_cpucache_magazine_alloc(kmem_cpu_cache_t * ccp,kmem_cache_t * cp)2595 kmem_cpucache_magazine_alloc(kmem_cpu_cache_t *ccp, kmem_cache_t *cp)
2596 {
2597 	kmem_magazine_t *emp;
2598 	kmem_magtype_t *mtp;
2599 
2600 	ASSERT(MUTEX_HELD(&ccp->cc_lock));
2601 	ASSERT(((uint_t)ccp->cc_rounds == ccp->cc_magsize ||
2602 	    ((uint_t)ccp->cc_rounds == -1)) &&
2603 	    ((uint_t)ccp->cc_prounds == ccp->cc_magsize ||
2604 	    ((uint_t)ccp->cc_prounds == -1)));
2605 
2606 	emp = kmem_depot_alloc(cp, &cp->cache_empty);
2607 	if (emp != NULL) {
2608 		if (ccp->cc_ploaded != NULL)
2609 			kmem_depot_free(cp, &cp->cache_full,
2610 			    ccp->cc_ploaded);
2611 		kmem_cpu_reload(ccp, emp, 0);
2612 		return (1);
2613 	}
2614 	/*
2615 	 * There are no empty magazines in the depot,
2616 	 * so try to allocate a new one.  We must drop all locks
2617 	 * across kmem_cache_alloc() because lower layers may
2618 	 * attempt to allocate from this cache.
2619 	 */
2620 	mtp = cp->cache_magtype;
2621 	mutex_exit(&ccp->cc_lock);
2622 	emp = kmem_cache_alloc(mtp->mt_cache, KM_NOSLEEP);
2623 	mutex_enter(&ccp->cc_lock);
2624 
2625 	if (emp != NULL) {
2626 		/*
2627 		 * We successfully allocated an empty magazine.
2628 		 * However, we had to drop ccp->cc_lock to do it,
2629 		 * so the cache's magazine size may have changed.
2630 		 * If so, free the magazine and try again.
2631 		 */
2632 		if (ccp->cc_magsize != mtp->mt_magsize) {
2633 			mutex_exit(&ccp->cc_lock);
2634 			kmem_cache_free(mtp->mt_cache, emp);
2635 			mutex_enter(&ccp->cc_lock);
2636 			return (1);
2637 		}
2638 
2639 		/*
2640 		 * We got a magazine of the right size.  Add it to
2641 		 * the depot and try the whole dance again.
2642 		 */
2643 		kmem_depot_free(cp, &cp->cache_empty, emp);
2644 		return (1);
2645 	}
2646 
2647 	/*
2648 	 * We couldn't allocate an empty magazine,
2649 	 * so fall through to the slab layer.
2650 	 */
2651 	return (0);
2652 }
2653 
2654 /*
2655  * Free a constructed object to cache cp.
2656  */
2657 void
kmem_cache_free(kmem_cache_t * cp,void * buf)2658 kmem_cache_free(kmem_cache_t *cp, void *buf)
2659 {
2660 	kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2661 
2662 	/*
2663 	 * The client must not free either of the buffers passed to the move
2664 	 * callback function.
2665 	 */
2666 	ASSERT(cp->cache_defrag == NULL ||
2667 	    cp->cache_defrag->kmd_thread != curthread ||
2668 	    (buf != cp->cache_defrag->kmd_from_buf &&
2669 	    buf != cp->cache_defrag->kmd_to_buf));
2670 
2671 	if (ccp->cc_flags & (KMF_BUFTAG | KMF_DUMPDIVERT | KMF_DUMPUNSAFE)) {
2672 		if (ccp->cc_flags & KMF_DUMPUNSAFE) {
2673 			ASSERT(!(ccp->cc_flags & KMF_DUMPDIVERT));
2674 			/* log it so that we can warn about it */
2675 			cp->cache_dump.kd_unsafe++;
2676 		} else if (KMEM_DUMPCC(ccp) && !kmem_cache_free_dump(cp, buf)) {
2677 			return;
2678 		}
2679 		if (ccp->cc_flags & KMF_BUFTAG) {
2680 			if (kmem_cache_free_debug(cp, buf, caller()) == -1)
2681 				return;
2682 		}
2683 	}
2684 
2685 	mutex_enter(&ccp->cc_lock);
2686 	/*
2687 	 * Any changes to this logic should be reflected in kmem_slab_prefill()
2688 	 */
2689 	for (;;) {
2690 		/*
2691 		 * If there's a slot available in the current CPU's
2692 		 * loaded magazine, just put the object there and return.
2693 		 */
2694 		if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2695 			ccp->cc_loaded->mag_round[ccp->cc_rounds++] = buf;
2696 			ccp->cc_free++;
2697 			mutex_exit(&ccp->cc_lock);
2698 			return;
2699 		}
2700 
2701 		/*
2702 		 * The loaded magazine is full.  If the previously loaded
2703 		 * magazine was empty, exchange them and try again.
2704 		 */
2705 		if (ccp->cc_prounds == 0) {
2706 			kmem_cpu_reload(ccp, ccp->cc_ploaded, ccp->cc_prounds);
2707 			continue;
2708 		}
2709 
2710 		/*
2711 		 * If the magazine layer is disabled, break out now.
2712 		 */
2713 		if (ccp->cc_magsize == 0)
2714 			break;
2715 
2716 		if (!kmem_cpucache_magazine_alloc(ccp, cp)) {
2717 			/*
2718 			 * We couldn't free our constructed object to the
2719 			 * magazine layer, so apply its destructor and free it
2720 			 * to the slab layer.
2721 			 */
2722 			break;
2723 		}
2724 	}
2725 	mutex_exit(&ccp->cc_lock);
2726 	kmem_slab_free_constructed(cp, buf, B_TRUE);
2727 }
2728 
2729 static void
kmem_slab_prefill(kmem_cache_t * cp,kmem_slab_t * sp)2730 kmem_slab_prefill(kmem_cache_t *cp, kmem_slab_t *sp)
2731 {
2732 	kmem_cpu_cache_t *ccp = KMEM_CPU_CACHE(cp);
2733 	int cache_flags = cp->cache_flags;
2734 
2735 	kmem_bufctl_t *next, *head;
2736 	size_t nbufs;
2737 
2738 	/*
2739 	 * Completely allocate the newly created slab and put the pre-allocated
2740 	 * buffers in magazines. Any of the buffers that cannot be put in
2741 	 * magazines must be returned to the slab.
2742 	 */
2743 	ASSERT(MUTEX_HELD(&cp->cache_lock));
2744 	ASSERT((cache_flags & (KMF_PREFILL|KMF_BUFTAG)) == KMF_PREFILL);
2745 	ASSERT(cp->cache_constructor == NULL);
2746 	ASSERT(sp->slab_cache == cp);
2747 	ASSERT(sp->slab_refcnt == 1);
2748 	ASSERT(sp->slab_head != NULL && sp->slab_chunks > sp->slab_refcnt);
2749 	ASSERT(avl_find(&cp->cache_partial_slabs, sp, NULL) == NULL);
2750 
2751 	head = sp->slab_head;
2752 	nbufs = (sp->slab_chunks - sp->slab_refcnt);
2753 	sp->slab_head = NULL;
2754 	sp->slab_refcnt += nbufs;
2755 	cp->cache_bufslab -= nbufs;
2756 	cp->cache_slab_alloc += nbufs;
2757 	list_insert_head(&cp->cache_complete_slabs, sp);
2758 	cp->cache_complete_slab_count++;
2759 	mutex_exit(&cp->cache_lock);
2760 	mutex_enter(&ccp->cc_lock);
2761 
2762 	while (head != NULL) {
2763 		void *buf = KMEM_BUF(cp, head);
2764 		/*
2765 		 * If there's a slot available in the current CPU's
2766 		 * loaded magazine, just put the object there and
2767 		 * continue.
2768 		 */
2769 		if ((uint_t)ccp->cc_rounds < ccp->cc_magsize) {
2770 			ccp->cc_loaded->mag_round[ccp->cc_rounds++] =
2771 			    buf;
2772 			ccp->cc_free++;
2773 			nbufs--;
2774 			head = head->bc_next;
2775 			continue;
2776 		}
2777 
2778 		/*
2779 		 * The loaded magazine is full.  If the previously
2780 		 * loaded magazine was empty, exchange them and try
2781 		 * again.
2782 		 */
2783 		if (ccp->cc_prounds == 0) {
2784 			kmem_cpu_reload(ccp, ccp->cc_ploaded,
2785 			    ccp->cc_prounds);
2786 			continue;
2787 		}
2788 
2789 		/*
2790 		 * If the magazine layer is disabled, break out now.
2791 		 */
2792 
2793 		if (ccp->cc_magsize == 0) {
2794 			break;
2795 		}
2796 
2797 		if (!kmem_cpucache_magazine_alloc(ccp, cp))
2798 			break;
2799 	}
2800 	mutex_exit(&ccp->cc_lock);
2801 	if (nbufs != 0) {
2802 		ASSERT(head != NULL);
2803 
2804 		/*
2805 		 * If there was a failure, return remaining objects to
2806 		 * the slab
2807 		 */
2808 		while (head != NULL) {
2809 			ASSERT(nbufs != 0);
2810 			next = head->bc_next;
2811 			head->bc_next = NULL;
2812 			kmem_slab_free(cp, KMEM_BUF(cp, head));
2813 			head = next;
2814 			nbufs--;
2815 		}
2816 	}
2817 	ASSERT(head == NULL);
2818 	ASSERT(nbufs == 0);
2819 	mutex_enter(&cp->cache_lock);
2820 }
2821 
2822 void *
kmem_zalloc(size_t size,int kmflag)2823 kmem_zalloc(size_t size, int kmflag)
2824 {
2825 	size_t index;
2826 	void *buf;
2827 
2828 	if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2829 		kmem_cache_t *cp = kmem_alloc_table[index];
2830 		buf = kmem_cache_alloc(cp, kmflag);
2831 		if (buf != NULL) {
2832 			if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2833 				kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2834 				((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2835 				((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2836 
2837 				if (cp->cache_flags & KMF_LITE) {
2838 					KMEM_BUFTAG_LITE_ENTER(btp,
2839 					    kmem_lite_count, caller());
2840 				}
2841 			}
2842 			bzero(buf, size);
2843 		}
2844 	} else {
2845 		buf = kmem_alloc(size, kmflag);
2846 		if (buf != NULL)
2847 			bzero(buf, size);
2848 	}
2849 	return (buf);
2850 }
2851 
2852 void *
kmem_alloc(size_t size,int kmflag)2853 kmem_alloc(size_t size, int kmflag)
2854 {
2855 	size_t index;
2856 	kmem_cache_t *cp;
2857 	void *buf;
2858 
2859 	if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2860 		cp = kmem_alloc_table[index];
2861 		/* fall through to kmem_cache_alloc() */
2862 
2863 	} else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2864 	    kmem_big_alloc_table_max) {
2865 		cp = kmem_big_alloc_table[index];
2866 		/* fall through to kmem_cache_alloc() */
2867 
2868 	} else {
2869 		if (size == 0) {
2870 			if (kmflag != KM_SLEEP && !(kmflag & KM_PANIC))
2871 				return (NULL);
2872 
2873 			/*
2874 			 * If this is a sleeping allocation or one that has
2875 			 * been specified to panic on allocation failure, we
2876 			 * consider it to be deprecated behavior to allocate
2877 			 * 0 bytes.  If we have been configured to panic under
2878 			 * this condition, we panic; if to warn, we warn -- and
2879 			 * regardless, we log to the kmem_zerosized_log that
2880 			 * that this condition has occurred (which gives us
2881 			 * enough information to be able to debug it).
2882 			 */
2883 			if (kmem_panic && kmem_panic_zerosized)
2884 				panic("attempted to kmem_alloc() size of 0");
2885 
2886 			if (kmem_warn_zerosized) {
2887 				cmn_err(CE_WARN, "kmem_alloc(): sleeping "
2888 				    "allocation with size of 0; "
2889 				    "see kmem_zerosized_log for details");
2890 			}
2891 
2892 			kmem_log_event(kmem_zerosized_log, NULL, NULL, NULL);
2893 
2894 			return (NULL);
2895 		}
2896 
2897 		buf = vmem_alloc(kmem_oversize_arena, size,
2898 		    kmflag & KM_VMFLAGS);
2899 		if (buf == NULL)
2900 			kmem_log_event(kmem_failure_log, NULL, NULL,
2901 			    (void *)size);
2902 		else if (KMEM_DUMP(kmem_slab_cache)) {
2903 			/* stats for dump intercept */
2904 			kmem_dump_oversize_allocs++;
2905 			if (size > kmem_dump_oversize_max)
2906 				kmem_dump_oversize_max = size;
2907 		}
2908 		return (buf);
2909 	}
2910 
2911 	buf = kmem_cache_alloc(cp, kmflag);
2912 	if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp) && buf != NULL) {
2913 		kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2914 		((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2915 		((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2916 
2917 		if (cp->cache_flags & KMF_LITE) {
2918 			KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller());
2919 		}
2920 	}
2921 	return (buf);
2922 }
2923 
2924 void
kmem_free(void * buf,size_t size)2925 kmem_free(void *buf, size_t size)
2926 {
2927 	size_t index;
2928 	kmem_cache_t *cp;
2929 
2930 	if ((index = (size - 1) >> KMEM_ALIGN_SHIFT) < KMEM_ALLOC_TABLE_MAX) {
2931 		cp = kmem_alloc_table[index];
2932 		/* fall through to kmem_cache_free() */
2933 
2934 	} else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2935 	    kmem_big_alloc_table_max) {
2936 		cp = kmem_big_alloc_table[index];
2937 		/* fall through to kmem_cache_free() */
2938 
2939 	} else {
2940 		EQUIV(buf == NULL, size == 0);
2941 		if (buf == NULL && size == 0)
2942 			return;
2943 		vmem_free(kmem_oversize_arena, buf, size);
2944 		return;
2945 	}
2946 
2947 	if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2948 		kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2949 		uint32_t *ip = (uint32_t *)btp;
2950 		if (ip[1] != KMEM_SIZE_ENCODE(size)) {
2951 			if (*(uint64_t *)buf == KMEM_FREE_PATTERN) {
2952 				kmem_error(KMERR_DUPFREE, cp, buf);
2953 				return;
2954 			}
2955 			if (KMEM_SIZE_VALID(ip[1])) {
2956 				ip[0] = KMEM_SIZE_ENCODE(size);
2957 				kmem_error(KMERR_BADSIZE, cp, buf);
2958 			} else {
2959 				kmem_error(KMERR_REDZONE, cp, buf);
2960 			}
2961 			return;
2962 		}
2963 		if (((uint8_t *)buf)[size] != KMEM_REDZONE_BYTE) {
2964 			kmem_error(KMERR_REDZONE, cp, buf);
2965 			return;
2966 		}
2967 		btp->bt_redzone = KMEM_REDZONE_PATTERN;
2968 		if (cp->cache_flags & KMF_LITE) {
2969 			KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count,
2970 			    caller());
2971 		}
2972 	}
2973 	kmem_cache_free(cp, buf);
2974 }
2975 
2976 void *
kmem_firewall_va_alloc(vmem_t * vmp,size_t size,int vmflag)2977 kmem_firewall_va_alloc(vmem_t *vmp, size_t size, int vmflag)
2978 {
2979 	size_t realsize = size + vmp->vm_quantum;
2980 	void *addr;
2981 
2982 	/*
2983 	 * Annoying edge case: if 'size' is just shy of ULONG_MAX, adding
2984 	 * vm_quantum will cause integer wraparound.  Check for this, and
2985 	 * blow off the firewall page in this case.  Note that such a
2986 	 * giant allocation (the entire kernel address space) can never
2987 	 * be satisfied, so it will either fail immediately (VM_NOSLEEP)
2988 	 * or sleep forever (VM_SLEEP).  Thus, there is no need for a
2989 	 * corresponding check in kmem_firewall_va_free().
2990 	 */
2991 	if (realsize < size)
2992 		realsize = size;
2993 
2994 	/*
2995 	 * While boot still owns resource management, make sure that this
2996 	 * redzone virtual address allocation is properly accounted for in
2997 	 * OBPs "virtual-memory" "available" lists because we're
2998 	 * effectively claiming them for a red zone.  If we don't do this,
2999 	 * the available lists become too fragmented and too large for the
3000 	 * current boot/kernel memory list interface.
3001 	 */
3002 	addr = vmem_alloc(vmp, realsize, vmflag | VM_NEXTFIT);
3003 
3004 	if (addr != NULL && kvseg.s_base == NULL && realsize != size)
3005 		(void) boot_virt_alloc((char *)addr + size, vmp->vm_quantum);
3006 
3007 	return (addr);
3008 }
3009 
3010 void
kmem_firewall_va_free(vmem_t * vmp,void * addr,size_t size)3011 kmem_firewall_va_free(vmem_t *vmp, void *addr, size_t size)
3012 {
3013 	ASSERT((kvseg.s_base == NULL ?
3014 	    va_to_pfn((char *)addr + size) :
3015 	    hat_getpfnum(kas.a_hat, (caddr_t)addr + size)) == PFN_INVALID);
3016 
3017 	vmem_free(vmp, addr, size + vmp->vm_quantum);
3018 }
3019 
3020 /*
3021  * Try to allocate at least `size' bytes of memory without sleeping or
3022  * panicking. Return actual allocated size in `asize'. If allocation failed,
3023  * try final allocation with sleep or panic allowed.
3024  */
3025 void *
kmem_alloc_tryhard(size_t size,size_t * asize,int kmflag)3026 kmem_alloc_tryhard(size_t size, size_t *asize, int kmflag)
3027 {
3028 	void *p;
3029 
3030 	*asize = P2ROUNDUP(size, KMEM_ALIGN);
3031 	do {
3032 		p = kmem_alloc(*asize, (kmflag | KM_NOSLEEP) & ~KM_PANIC);
3033 		if (p != NULL)
3034 			return (p);
3035 		*asize += KMEM_ALIGN;
3036 	} while (*asize <= PAGESIZE);
3037 
3038 	*asize = P2ROUNDUP(size, KMEM_ALIGN);
3039 	return (kmem_alloc(*asize, kmflag));
3040 }
3041 
3042 /*
3043  * Reclaim all unused memory from a cache.
3044  */
3045 static void
kmem_cache_reap(kmem_cache_t * cp)3046 kmem_cache_reap(kmem_cache_t *cp)
3047 {
3048 	ASSERT(taskq_member(kmem_taskq, curthread));
3049 	cp->cache_reap++;
3050 
3051 	/*
3052 	 * Ask the cache's owner to free some memory if possible.
3053 	 * The idea is to handle things like the inode cache, which
3054 	 * typically sits on a bunch of memory that it doesn't truly
3055 	 * *need*.  Reclaim policy is entirely up to the owner; this
3056 	 * callback is just an advisory plea for help.
3057 	 */
3058 	if (cp->cache_reclaim != NULL) {
3059 		long delta;
3060 
3061 		/*
3062 		 * Reclaimed memory should be reapable (not included in the
3063 		 * depot's working set).
3064 		 */
3065 		delta = cp->cache_full.ml_total;
3066 		cp->cache_reclaim(cp->cache_private);
3067 		delta = cp->cache_full.ml_total - delta;
3068 		if (delta > 0) {
3069 			mutex_enter(&cp->cache_depot_lock);
3070 			cp->cache_full.ml_reaplimit += delta;
3071 			cp->cache_full.ml_min += delta;
3072 			mutex_exit(&cp->cache_depot_lock);
3073 		}
3074 	}
3075 
3076 	kmem_depot_ws_reap(cp);
3077 
3078 	if (cp->cache_defrag != NULL && !kmem_move_noreap) {
3079 		kmem_cache_defrag(cp);
3080 	}
3081 }
3082 
3083 static void
kmem_reap_timeout(void * flag_arg)3084 kmem_reap_timeout(void *flag_arg)
3085 {
3086 	uint32_t *flag = (uint32_t *)flag_arg;
3087 
3088 	ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3089 	*flag = 0;
3090 }
3091 
3092 static void
kmem_reap_done(void * flag)3093 kmem_reap_done(void *flag)
3094 {
3095 	if (!callout_init_done) {
3096 		/* can't schedule a timeout at this point */
3097 		kmem_reap_timeout(flag);
3098 	} else {
3099 		(void) timeout(kmem_reap_timeout, flag, kmem_reap_interval);
3100 	}
3101 }
3102 
3103 static void
kmem_reap_start(void * flag)3104 kmem_reap_start(void *flag)
3105 {
3106 	ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3107 
3108 	if (flag == &kmem_reaping) {
3109 		kmem_cache_applyall(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3110 		/*
3111 		 * if we have segkp under heap, reap segkp cache.
3112 		 */
3113 		if (segkp_fromheap)
3114 			segkp_cache_free();
3115 	}
3116 	else
3117 		kmem_cache_applyall_id(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3118 
3119 	/*
3120 	 * We use taskq_dispatch() to schedule a timeout to clear
3121 	 * the flag so that kmem_reap() becomes self-throttling:
3122 	 * we won't reap again until the current reap completes *and*
3123 	 * at least kmem_reap_interval ticks have elapsed.
3124 	 */
3125 	if (taskq_dispatch(kmem_taskq, kmem_reap_done, flag, TQ_NOSLEEP) ==
3126 	    TASKQID_INVALID)
3127 		kmem_reap_done(flag);
3128 }
3129 
3130 static void
kmem_reap_common(void * flag_arg)3131 kmem_reap_common(void *flag_arg)
3132 {
3133 	uint32_t *flag = (uint32_t *)flag_arg;
3134 
3135 	if (MUTEX_HELD(&kmem_cache_lock) || kmem_taskq == NULL ||
3136 	    atomic_cas_32(flag, 0, 1) != 0)
3137 		return;
3138 
3139 	/*
3140 	 * It may not be kosher to do memory allocation when a reap is called
3141 	 * (for example, if vmem_populate() is in the call chain).  So we
3142 	 * start the reap going with a TQ_NOALLOC dispatch.  If the dispatch
3143 	 * fails, we reset the flag, and the next reap will try again.
3144 	 */
3145 	if (taskq_dispatch(kmem_taskq, kmem_reap_start, flag, TQ_NOALLOC) ==
3146 	    TASKQID_INVALID)
3147 		*flag = 0;
3148 }
3149 
3150 /*
3151  * Reclaim all unused memory from all caches.  Called from the VM system
3152  * when memory gets tight.
3153  */
3154 void
kmem_reap(void)3155 kmem_reap(void)
3156 {
3157 	kmem_reap_common(&kmem_reaping);
3158 }
3159 
3160 /*
3161  * Reclaim all unused memory from identifier arenas, called when a vmem
3162  * arena not back by memory is exhausted.  Since reaping memory-backed caches
3163  * cannot help with identifier exhaustion, we avoid both a large amount of
3164  * work and unwanted side-effects from reclaim callbacks.
3165  */
3166 void
kmem_reap_idspace(void)3167 kmem_reap_idspace(void)
3168 {
3169 	kmem_reap_common(&kmem_reaping_idspace);
3170 }
3171 
3172 /*
3173  * Purge all magazines from a cache and set its magazine limit to zero.
3174  * All calls are serialized by the kmem_taskq lock, except for the final
3175  * call from kmem_cache_destroy().
3176  */
3177 static void
kmem_cache_magazine_purge(kmem_cache_t * cp)3178 kmem_cache_magazine_purge(kmem_cache_t *cp)
3179 {
3180 	kmem_cpu_cache_t *ccp;
3181 	kmem_magazine_t *mp, *pmp;
3182 	int rounds, prounds, cpu_seqid;
3183 
3184 	ASSERT(!list_link_active(&cp->cache_link) ||
3185 	    taskq_member(kmem_taskq, curthread));
3186 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
3187 
3188 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3189 		ccp = &cp->cache_cpu[cpu_seqid];
3190 
3191 		mutex_enter(&ccp->cc_lock);
3192 		mp = ccp->cc_loaded;
3193 		pmp = ccp->cc_ploaded;
3194 		rounds = ccp->cc_rounds;
3195 		prounds = ccp->cc_prounds;
3196 		ccp->cc_loaded = NULL;
3197 		ccp->cc_ploaded = NULL;
3198 		ccp->cc_rounds = -1;
3199 		ccp->cc_prounds = -1;
3200 		ccp->cc_magsize = 0;
3201 		mutex_exit(&ccp->cc_lock);
3202 
3203 		if (mp)
3204 			kmem_magazine_destroy(cp, mp, rounds);
3205 		if (pmp)
3206 			kmem_magazine_destroy(cp, pmp, prounds);
3207 	}
3208 
3209 	kmem_depot_ws_zero(cp);
3210 	kmem_depot_ws_reap(cp);
3211 }
3212 
3213 /*
3214  * Enable per-cpu magazines on a cache.
3215  */
3216 static void
kmem_cache_magazine_enable(kmem_cache_t * cp)3217 kmem_cache_magazine_enable(kmem_cache_t *cp)
3218 {
3219 	int cpu_seqid;
3220 
3221 	if (cp->cache_flags & KMF_NOMAGAZINE)
3222 		return;
3223 
3224 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3225 		kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3226 		mutex_enter(&ccp->cc_lock);
3227 		ccp->cc_magsize = cp->cache_magtype->mt_magsize;
3228 		mutex_exit(&ccp->cc_lock);
3229 	}
3230 
3231 }
3232 
3233 /*
3234  * Allow our caller to determine if there are running reaps.
3235  *
3236  * This call is very conservative and may return B_TRUE even when
3237  * reaping activity isn't active. If it returns B_FALSE, then reaping
3238  * activity is definitely inactive.
3239  */
3240 boolean_t
kmem_cache_reap_active(void)3241 kmem_cache_reap_active(void)
3242 {
3243 	return (!taskq_empty(kmem_taskq));
3244 }
3245 
3246 /*
3247  * Reap (almost) everything soon.
3248  *
3249  * Note: this does not wait for the reap-tasks to complete. Caller
3250  * should use kmem_cache_reap_active() (above) and/or moderation to
3251  * avoid scheduling too many reap-tasks.
3252  */
3253 void
kmem_cache_reap_soon(kmem_cache_t * cp)3254 kmem_cache_reap_soon(kmem_cache_t *cp)
3255 {
3256 	ASSERT(list_link_active(&cp->cache_link));
3257 
3258 	kmem_depot_ws_zero(cp);
3259 
3260 	(void) taskq_dispatch(kmem_taskq,
3261 	    (task_func_t *)kmem_depot_ws_reap, cp, TQ_SLEEP);
3262 }
3263 
3264 /*
3265  * Recompute a cache's magazine size.  The trade-off is that larger magazines
3266  * provide a higher transfer rate with the depot, while smaller magazines
3267  * reduce memory consumption.  Magazine resizing is an expensive operation;
3268  * it should not be done frequently.
3269  *
3270  * Changes to the magazine size are serialized by the kmem_taskq lock.
3271  *
3272  * Note: at present this only grows the magazine size.  It might be useful
3273  * to allow shrinkage too.
3274  */
3275 static void
kmem_cache_magazine_resize(kmem_cache_t * cp)3276 kmem_cache_magazine_resize(kmem_cache_t *cp)
3277 {
3278 	kmem_magtype_t *mtp = cp->cache_magtype;
3279 
3280 	ASSERT(taskq_member(kmem_taskq, curthread));
3281 
3282 	if (cp->cache_chunksize < mtp->mt_maxbuf) {
3283 		kmem_cache_magazine_purge(cp);
3284 		mutex_enter(&cp->cache_depot_lock);
3285 		cp->cache_magtype = ++mtp;
3286 		cp->cache_depot_contention_prev =
3287 		    cp->cache_depot_contention + INT_MAX;
3288 		mutex_exit(&cp->cache_depot_lock);
3289 		kmem_cache_magazine_enable(cp);
3290 	}
3291 }
3292 
3293 /*
3294  * Rescale a cache's hash table, so that the table size is roughly the
3295  * cache size.  We want the average lookup time to be extremely small.
3296  */
3297 static void
kmem_hash_rescale(kmem_cache_t * cp)3298 kmem_hash_rescale(kmem_cache_t *cp)
3299 {
3300 	kmem_bufctl_t **old_table, **new_table, *bcp;
3301 	size_t old_size, new_size, h;
3302 
3303 	ASSERT(taskq_member(kmem_taskq, curthread));
3304 
3305 	new_size = MAX(KMEM_HASH_INITIAL,
3306 	    1 << (highbit(3 * cp->cache_buftotal + 4) - 2));
3307 	old_size = cp->cache_hash_mask + 1;
3308 
3309 	if ((old_size >> 1) <= new_size && new_size <= (old_size << 1))
3310 		return;
3311 
3312 	new_table = vmem_alloc(kmem_hash_arena, new_size * sizeof (void *),
3313 	    VM_NOSLEEP);
3314 	if (new_table == NULL)
3315 		return;
3316 	bzero(new_table, new_size * sizeof (void *));
3317 
3318 	mutex_enter(&cp->cache_lock);
3319 
3320 	old_size = cp->cache_hash_mask + 1;
3321 	old_table = cp->cache_hash_table;
3322 
3323 	cp->cache_hash_mask = new_size - 1;
3324 	cp->cache_hash_table = new_table;
3325 	cp->cache_rescale++;
3326 
3327 	for (h = 0; h < old_size; h++) {
3328 		bcp = old_table[h];
3329 		while (bcp != NULL) {
3330 			void *addr = bcp->bc_addr;
3331 			kmem_bufctl_t *next_bcp = bcp->bc_next;
3332 			kmem_bufctl_t **hash_bucket = KMEM_HASH(cp, addr);
3333 			bcp->bc_next = *hash_bucket;
3334 			*hash_bucket = bcp;
3335 			bcp = next_bcp;
3336 		}
3337 	}
3338 
3339 	mutex_exit(&cp->cache_lock);
3340 
3341 	vmem_free(kmem_hash_arena, old_table, old_size * sizeof (void *));
3342 }
3343 
3344 /*
3345  * Perform periodic maintenance on a cache: hash rescaling, depot working-set
3346  * update, magazine resizing, and slab consolidation.
3347  */
3348 static void
kmem_cache_update(kmem_cache_t * cp)3349 kmem_cache_update(kmem_cache_t *cp)
3350 {
3351 	int need_hash_rescale = 0;
3352 	int need_magazine_resize = 0;
3353 
3354 	ASSERT(MUTEX_HELD(&kmem_cache_lock));
3355 
3356 	/*
3357 	 * If the cache has become much larger or smaller than its hash table,
3358 	 * fire off a request to rescale the hash table.
3359 	 */
3360 	mutex_enter(&cp->cache_lock);
3361 
3362 	if ((cp->cache_flags & KMF_HASH) &&
3363 	    (cp->cache_buftotal > (cp->cache_hash_mask << 1) ||
3364 	    (cp->cache_buftotal < (cp->cache_hash_mask >> 1) &&
3365 	    cp->cache_hash_mask > KMEM_HASH_INITIAL)))
3366 		need_hash_rescale = 1;
3367 
3368 	mutex_exit(&cp->cache_lock);
3369 
3370 	/*
3371 	 * Update the depot working set statistics.
3372 	 */
3373 	kmem_depot_ws_update(cp);
3374 
3375 	/*
3376 	 * If there's a lot of contention in the depot,
3377 	 * increase the magazine size.
3378 	 */
3379 	mutex_enter(&cp->cache_depot_lock);
3380 
3381 	if (cp->cache_chunksize < cp->cache_magtype->mt_maxbuf &&
3382 	    (int)(cp->cache_depot_contention -
3383 	    cp->cache_depot_contention_prev) > kmem_depot_contention)
3384 		need_magazine_resize = 1;
3385 
3386 	cp->cache_depot_contention_prev = cp->cache_depot_contention;
3387 
3388 	mutex_exit(&cp->cache_depot_lock);
3389 
3390 	if (need_hash_rescale)
3391 		(void) taskq_dispatch(kmem_taskq,
3392 		    (task_func_t *)kmem_hash_rescale, cp, TQ_NOSLEEP);
3393 
3394 	if (need_magazine_resize)
3395 		(void) taskq_dispatch(kmem_taskq,
3396 		    (task_func_t *)kmem_cache_magazine_resize, cp, TQ_NOSLEEP);
3397 
3398 	if (cp->cache_defrag != NULL)
3399 		(void) taskq_dispatch(kmem_taskq,
3400 		    (task_func_t *)kmem_cache_scan, cp, TQ_NOSLEEP);
3401 }
3402 
3403 static void kmem_update(void *);
3404 
3405 static void
kmem_update_timeout(void * dummy)3406 kmem_update_timeout(void *dummy)
3407 {
3408 	(void) timeout(kmem_update, dummy, kmem_reap_interval);
3409 }
3410 
3411 static void
kmem_update(void * dummy)3412 kmem_update(void *dummy)
3413 {
3414 	kmem_cache_applyall(kmem_cache_update, NULL, TQ_NOSLEEP);
3415 
3416 	/*
3417 	 * We use taskq_dispatch() to reschedule the timeout so that
3418 	 * kmem_update() becomes self-throttling: it won't schedule
3419 	 * new tasks until all previous tasks have completed.
3420 	 */
3421 	if (taskq_dispatch(kmem_taskq, kmem_update_timeout, dummy, TQ_NOSLEEP)
3422 	    == TASKQID_INVALID)
3423 		kmem_update_timeout(NULL);
3424 }
3425 
3426 static int
kmem_cache_kstat_update(kstat_t * ksp,int rw)3427 kmem_cache_kstat_update(kstat_t *ksp, int rw)
3428 {
3429 	struct kmem_cache_kstat *kmcp = &kmem_cache_kstat;
3430 	kmem_cache_t *cp = ksp->ks_private;
3431 	uint64_t cpu_buf_avail;
3432 	uint64_t buf_avail = 0;
3433 	int cpu_seqid;
3434 	long reap;
3435 
3436 	ASSERT(MUTEX_HELD(&kmem_cache_kstat_lock));
3437 
3438 	if (rw == KSTAT_WRITE)
3439 		return (EACCES);
3440 
3441 	mutex_enter(&cp->cache_lock);
3442 
3443 	kmcp->kmc_alloc_fail.value.ui64		= cp->cache_alloc_fail;
3444 	kmcp->kmc_alloc.value.ui64		= cp->cache_slab_alloc;
3445 	kmcp->kmc_free.value.ui64		= cp->cache_slab_free;
3446 	kmcp->kmc_slab_alloc.value.ui64		= cp->cache_slab_alloc;
3447 	kmcp->kmc_slab_free.value.ui64		= cp->cache_slab_free;
3448 
3449 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3450 		kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3451 
3452 		mutex_enter(&ccp->cc_lock);
3453 
3454 		cpu_buf_avail = 0;
3455 		if (ccp->cc_rounds > 0)
3456 			cpu_buf_avail += ccp->cc_rounds;
3457 		if (ccp->cc_prounds > 0)
3458 			cpu_buf_avail += ccp->cc_prounds;
3459 
3460 		kmcp->kmc_alloc.value.ui64	+= ccp->cc_alloc;
3461 		kmcp->kmc_free.value.ui64	+= ccp->cc_free;
3462 		buf_avail			+= cpu_buf_avail;
3463 
3464 		mutex_exit(&ccp->cc_lock);
3465 	}
3466 
3467 	mutex_enter(&cp->cache_depot_lock);
3468 
3469 	kmcp->kmc_depot_alloc.value.ui64	= cp->cache_full.ml_alloc;
3470 	kmcp->kmc_depot_free.value.ui64		= cp->cache_empty.ml_alloc;
3471 	kmcp->kmc_depot_contention.value.ui64	= cp->cache_depot_contention;
3472 	kmcp->kmc_full_magazines.value.ui64	= cp->cache_full.ml_total;
3473 	kmcp->kmc_empty_magazines.value.ui64	= cp->cache_empty.ml_total;
3474 	kmcp->kmc_magazine_size.value.ui64	=
3475 	    (cp->cache_flags & KMF_NOMAGAZINE) ?
3476 	    0 : cp->cache_magtype->mt_magsize;
3477 
3478 	kmcp->kmc_alloc.value.ui64		+= cp->cache_full.ml_alloc;
3479 	kmcp->kmc_free.value.ui64		+= cp->cache_empty.ml_alloc;
3480 	buf_avail += cp->cache_full.ml_total * cp->cache_magtype->mt_magsize;
3481 
3482 	reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
3483 	reap = MIN(reap, cp->cache_full.ml_total);
3484 
3485 	mutex_exit(&cp->cache_depot_lock);
3486 
3487 	kmcp->kmc_buf_size.value.ui64	= cp->cache_bufsize;
3488 	kmcp->kmc_align.value.ui64	= cp->cache_align;
3489 	kmcp->kmc_chunk_size.value.ui64	= cp->cache_chunksize;
3490 	kmcp->kmc_slab_size.value.ui64	= cp->cache_slabsize;
3491 	kmcp->kmc_buf_constructed.value.ui64 = buf_avail;
3492 	buf_avail += cp->cache_bufslab;
3493 	kmcp->kmc_buf_avail.value.ui64	= buf_avail;
3494 	kmcp->kmc_buf_inuse.value.ui64	= cp->cache_buftotal - buf_avail;
3495 	kmcp->kmc_buf_total.value.ui64	= cp->cache_buftotal;
3496 	kmcp->kmc_buf_max.value.ui64	= cp->cache_bufmax;
3497 	kmcp->kmc_slab_create.value.ui64	= cp->cache_slab_create;
3498 	kmcp->kmc_slab_destroy.value.ui64	= cp->cache_slab_destroy;
3499 	kmcp->kmc_hash_size.value.ui64	= (cp->cache_flags & KMF_HASH) ?
3500 	    cp->cache_hash_mask + 1 : 0;
3501 	kmcp->kmc_hash_lookup_depth.value.ui64	= cp->cache_lookup_depth;
3502 	kmcp->kmc_hash_rescale.value.ui64	= cp->cache_rescale;
3503 	kmcp->kmc_vmem_source.value.ui64	= cp->cache_arena->vm_id;
3504 	kmcp->kmc_reap.value.ui64	= cp->cache_reap;
3505 
3506 	if (cp->cache_defrag == NULL) {
3507 		kmcp->kmc_move_callbacks.value.ui64	= 0;
3508 		kmcp->kmc_move_yes.value.ui64		= 0;
3509 		kmcp->kmc_move_no.value.ui64		= 0;
3510 		kmcp->kmc_move_later.value.ui64		= 0;
3511 		kmcp->kmc_move_dont_need.value.ui64	= 0;
3512 		kmcp->kmc_move_dont_know.value.ui64	= 0;
3513 		kmcp->kmc_move_hunt_found.value.ui64	= 0;
3514 		kmcp->kmc_move_slabs_freed.value.ui64	= 0;
3515 		kmcp->kmc_defrag.value.ui64		= 0;
3516 		kmcp->kmc_scan.value.ui64		= 0;
3517 		kmcp->kmc_move_reclaimable.value.ui64	= 0;
3518 	} else {
3519 		int64_t reclaimable;
3520 
3521 		kmem_defrag_t *kd = cp->cache_defrag;
3522 		kmcp->kmc_move_callbacks.value.ui64	= kd->kmd_callbacks;
3523 		kmcp->kmc_move_yes.value.ui64		= kd->kmd_yes;
3524 		kmcp->kmc_move_no.value.ui64		= kd->kmd_no;
3525 		kmcp->kmc_move_later.value.ui64		= kd->kmd_later;
3526 		kmcp->kmc_move_dont_need.value.ui64	= kd->kmd_dont_need;
3527 		kmcp->kmc_move_dont_know.value.ui64	= kd->kmd_dont_know;
3528 		kmcp->kmc_move_hunt_found.value.ui64	= 0;
3529 		kmcp->kmc_move_slabs_freed.value.ui64	= kd->kmd_slabs_freed;
3530 		kmcp->kmc_defrag.value.ui64		= kd->kmd_defrags;
3531 		kmcp->kmc_scan.value.ui64		= kd->kmd_scans;
3532 
3533 		reclaimable = cp->cache_bufslab - (cp->cache_maxchunks - 1);
3534 		reclaimable = MAX(reclaimable, 0);
3535 		reclaimable += ((uint64_t)reap * cp->cache_magtype->mt_magsize);
3536 		kmcp->kmc_move_reclaimable.value.ui64	= reclaimable;
3537 	}
3538 
3539 	mutex_exit(&cp->cache_lock);
3540 	return (0);
3541 }
3542 
3543 /*
3544  * Return a named statistic about a particular cache.
3545  * This shouldn't be called very often, so it's currently designed for
3546  * simplicity (leverages existing kstat support) rather than efficiency.
3547  */
3548 uint64_t
kmem_cache_stat(kmem_cache_t * cp,char * name)3549 kmem_cache_stat(kmem_cache_t *cp, char *name)
3550 {
3551 	int i;
3552 	kstat_t *ksp = cp->cache_kstat;
3553 	kstat_named_t *knp = (kstat_named_t *)&kmem_cache_kstat;
3554 	uint64_t value = 0;
3555 
3556 	if (