xref: /illumos-gate/usr/src/uts/common/os/kmem.c (revision ed093b41a93e8563e6e1e5dae0768dda2a7bcc27)
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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(8) 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 /*
2823  * kmem_rezalloc() is currently considered private and subject to change until
2824  * we sort out how we want to handle realloc vs. reallocf style interfaces. We
2825  * have currently chosen realloc.
2826  */
2827 void *
kmem_rezalloc(void * oldbuf,size_t oldsize,size_t newsize,int kmflag)2828 kmem_rezalloc(void *oldbuf, size_t oldsize, size_t newsize, int kmflag)
2829 {
2830 	void *newbuf = kmem_alloc(newsize, kmflag);
2831 	if (newbuf == NULL) {
2832 		return (NULL);
2833 	}
2834 
2835 	bcopy(oldbuf, newbuf, MIN(oldsize, newsize));
2836 	if (newsize > oldsize) {
2837 		void *start = (void *)((uintptr_t)newbuf + oldsize);
2838 		bzero(start, newsize - oldsize);
2839 	}
2840 
2841 	if (oldbuf != NULL) {
2842 		ASSERT3U(oldsize, !=, 0);
2843 		kmem_free(oldbuf, oldsize);
2844 	}
2845 
2846 	return (newbuf);
2847 }
2848 
2849 void *
kmem_zalloc(size_t size,int kmflag)2850 kmem_zalloc(size_t size, int kmflag)
2851 {
2852 	size_t index;
2853 	void *buf;
2854 
2855 	if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2856 		kmem_cache_t *cp = kmem_alloc_table[index];
2857 		buf = kmem_cache_alloc(cp, kmflag);
2858 		if (buf != NULL) {
2859 			if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2860 				kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2861 				((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2862 				((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2863 
2864 				if (cp->cache_flags & KMF_LITE) {
2865 					KMEM_BUFTAG_LITE_ENTER(btp,
2866 					    kmem_lite_count, caller());
2867 				}
2868 			}
2869 			bzero(buf, size);
2870 		}
2871 	} else {
2872 		buf = kmem_alloc(size, kmflag);
2873 		if (buf != NULL)
2874 			bzero(buf, size);
2875 	}
2876 	return (buf);
2877 }
2878 
2879 void *
kmem_alloc(size_t size,int kmflag)2880 kmem_alloc(size_t size, int kmflag)
2881 {
2882 	size_t index;
2883 	kmem_cache_t *cp;
2884 	void *buf;
2885 
2886 	if ((index = ((size - 1) >> KMEM_ALIGN_SHIFT)) < KMEM_ALLOC_TABLE_MAX) {
2887 		cp = kmem_alloc_table[index];
2888 		/* fall through to kmem_cache_alloc() */
2889 
2890 	} else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2891 	    kmem_big_alloc_table_max) {
2892 		cp = kmem_big_alloc_table[index];
2893 		/* fall through to kmem_cache_alloc() */
2894 
2895 	} else {
2896 		if (size == 0) {
2897 			if (kmflag != KM_SLEEP && !(kmflag & KM_PANIC))
2898 				return (NULL);
2899 
2900 			/*
2901 			 * If this is a sleeping allocation or one that has
2902 			 * been specified to panic on allocation failure, we
2903 			 * consider it to be deprecated behavior to allocate
2904 			 * 0 bytes.  If we have been configured to panic under
2905 			 * this condition, we panic; if to warn, we warn -- and
2906 			 * regardless, we log to the kmem_zerosized_log that
2907 			 * that this condition has occurred (which gives us
2908 			 * enough information to be able to debug it).
2909 			 */
2910 			if (kmem_panic && kmem_panic_zerosized)
2911 				panic("attempted to kmem_alloc() size of 0");
2912 
2913 			if (kmem_warn_zerosized) {
2914 				cmn_err(CE_WARN, "kmem_alloc(): sleeping "
2915 				    "allocation with size of 0; "
2916 				    "see kmem_zerosized_log for details");
2917 			}
2918 
2919 			kmem_log_event(kmem_zerosized_log, NULL, NULL, NULL);
2920 
2921 			return (NULL);
2922 		}
2923 
2924 		buf = vmem_alloc(kmem_oversize_arena, size,
2925 		    kmflag & KM_VMFLAGS);
2926 		if (buf == NULL)
2927 			kmem_log_event(kmem_failure_log, NULL, NULL,
2928 			    (void *)size);
2929 		else if (KMEM_DUMP(kmem_slab_cache)) {
2930 			/* stats for dump intercept */
2931 			kmem_dump_oversize_allocs++;
2932 			if (size > kmem_dump_oversize_max)
2933 				kmem_dump_oversize_max = size;
2934 		}
2935 		return (buf);
2936 	}
2937 
2938 	buf = kmem_cache_alloc(cp, kmflag);
2939 	if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp) && buf != NULL) {
2940 		kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2941 		((uint8_t *)buf)[size] = KMEM_REDZONE_BYTE;
2942 		((uint32_t *)btp)[1] = KMEM_SIZE_ENCODE(size);
2943 
2944 		if (cp->cache_flags & KMF_LITE) {
2945 			KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count, caller());
2946 		}
2947 	}
2948 	return (buf);
2949 }
2950 
2951 void
kmem_free(void * buf,size_t size)2952 kmem_free(void *buf, size_t size)
2953 {
2954 	size_t index;
2955 	kmem_cache_t *cp;
2956 
2957 	if ((index = (size - 1) >> KMEM_ALIGN_SHIFT) < KMEM_ALLOC_TABLE_MAX) {
2958 		cp = kmem_alloc_table[index];
2959 		/* fall through to kmem_cache_free() */
2960 
2961 	} else if ((index = ((size - 1) >> KMEM_BIG_SHIFT)) <
2962 	    kmem_big_alloc_table_max) {
2963 		cp = kmem_big_alloc_table[index];
2964 		/* fall through to kmem_cache_free() */
2965 
2966 	} else {
2967 		EQUIV(buf == NULL, size == 0);
2968 		if (buf == NULL && size == 0)
2969 			return;
2970 		vmem_free(kmem_oversize_arena, buf, size);
2971 		return;
2972 	}
2973 
2974 	if ((cp->cache_flags & KMF_BUFTAG) && !KMEM_DUMP(cp)) {
2975 		kmem_buftag_t *btp = KMEM_BUFTAG(cp, buf);
2976 		uint32_t *ip = (uint32_t *)btp;
2977 		if (ip[1] != KMEM_SIZE_ENCODE(size)) {
2978 			if (*(uint64_t *)buf == KMEM_FREE_PATTERN) {
2979 				kmem_error(KMERR_DUPFREE, cp, buf);
2980 				return;
2981 			}
2982 			if (KMEM_SIZE_VALID(ip[1])) {
2983 				ip[0] = KMEM_SIZE_ENCODE(size);
2984 				kmem_error(KMERR_BADSIZE, cp, buf);
2985 			} else {
2986 				kmem_error(KMERR_REDZONE, cp, buf);
2987 			}
2988 			return;
2989 		}
2990 		if (((uint8_t *)buf)[size] != KMEM_REDZONE_BYTE) {
2991 			kmem_error(KMERR_REDZONE, cp, buf);
2992 			return;
2993 		}
2994 		btp->bt_redzone = KMEM_REDZONE_PATTERN;
2995 		if (cp->cache_flags & KMF_LITE) {
2996 			KMEM_BUFTAG_LITE_ENTER(btp, kmem_lite_count,
2997 			    caller());
2998 		}
2999 	}
3000 	kmem_cache_free(cp, buf);
3001 }
3002 
3003 void *
kmem_firewall_va_alloc(vmem_t * vmp,size_t size,int vmflag)3004 kmem_firewall_va_alloc(vmem_t *vmp, size_t size, int vmflag)
3005 {
3006 	size_t realsize = size + vmp->vm_quantum;
3007 	void *addr;
3008 
3009 	/*
3010 	 * Annoying edge case: if 'size' is just shy of ULONG_MAX, adding
3011 	 * vm_quantum will cause integer wraparound.  Check for this, and
3012 	 * blow off the firewall page in this case.  Note that such a
3013 	 * giant allocation (the entire kernel address space) can never
3014 	 * be satisfied, so it will either fail immediately (VM_NOSLEEP)
3015 	 * or sleep forever (VM_SLEEP).  Thus, there is no need for a
3016 	 * corresponding check in kmem_firewall_va_free().
3017 	 */
3018 	if (realsize < size)
3019 		realsize = size;
3020 
3021 	/*
3022 	 * While boot still owns resource management, make sure that this
3023 	 * redzone virtual address allocation is properly accounted for in
3024 	 * OBPs "virtual-memory" "available" lists because we're
3025 	 * effectively claiming them for a red zone.  If we don't do this,
3026 	 * the available lists become too fragmented and too large for the
3027 	 * current boot/kernel memory list interface.
3028 	 */
3029 	addr = vmem_alloc(vmp, realsize, vmflag | VM_NEXTFIT);
3030 
3031 	if (addr != NULL && kvseg.s_base == NULL && realsize != size)
3032 		(void) boot_virt_alloc((char *)addr + size, vmp->vm_quantum);
3033 
3034 	return (addr);
3035 }
3036 
3037 void
kmem_firewall_va_free(vmem_t * vmp,void * addr,size_t size)3038 kmem_firewall_va_free(vmem_t *vmp, void *addr, size_t size)
3039 {
3040 	ASSERT((kvseg.s_base == NULL ?
3041 	    va_to_pfn((char *)addr + size) :
3042 	    hat_getpfnum(kas.a_hat, (caddr_t)addr + size)) == PFN_INVALID);
3043 
3044 	vmem_free(vmp, addr, size + vmp->vm_quantum);
3045 }
3046 
3047 /*
3048  * Try to allocate at least `size' bytes of memory without sleeping or
3049  * panicking. Return actual allocated size in `asize'. If allocation failed,
3050  * try final allocation with sleep or panic allowed.
3051  */
3052 void *
kmem_alloc_tryhard(size_t size,size_t * asize,int kmflag)3053 kmem_alloc_tryhard(size_t size, size_t *asize, int kmflag)
3054 {
3055 	void *p;
3056 
3057 	*asize = P2ROUNDUP(size, KMEM_ALIGN);
3058 	do {
3059 		p = kmem_alloc(*asize, (kmflag | KM_NOSLEEP) & ~KM_PANIC);
3060 		if (p != NULL)
3061 			return (p);
3062 		*asize += KMEM_ALIGN;
3063 	} while (*asize <= PAGESIZE);
3064 
3065 	*asize = P2ROUNDUP(size, KMEM_ALIGN);
3066 	return (kmem_alloc(*asize, kmflag));
3067 }
3068 
3069 /*
3070  * Reclaim all unused memory from a cache.
3071  */
3072 static void
kmem_cache_reap(kmem_cache_t * cp)3073 kmem_cache_reap(kmem_cache_t *cp)
3074 {
3075 	ASSERT(taskq_member(kmem_taskq, curthread));
3076 	cp->cache_reap++;
3077 
3078 	/*
3079 	 * Ask the cache's owner to free some memory if possible.
3080 	 * The idea is to handle things like the inode cache, which
3081 	 * typically sits on a bunch of memory that it doesn't truly
3082 	 * *need*.  Reclaim policy is entirely up to the owner; this
3083 	 * callback is just an advisory plea for help.
3084 	 */
3085 	if (cp->cache_reclaim != NULL) {
3086 		long delta;
3087 
3088 		/*
3089 		 * Reclaimed memory should be reapable (not included in the
3090 		 * depot's working set).
3091 		 */
3092 		delta = cp->cache_full.ml_total;
3093 		cp->cache_reclaim(cp->cache_private);
3094 		delta = cp->cache_full.ml_total - delta;
3095 		if (delta > 0) {
3096 			mutex_enter(&cp->cache_depot_lock);
3097 			cp->cache_full.ml_reaplimit += delta;
3098 			cp->cache_full.ml_min += delta;
3099 			mutex_exit(&cp->cache_depot_lock);
3100 		}
3101 	}
3102 
3103 	kmem_depot_ws_reap(cp);
3104 
3105 	if (cp->cache_defrag != NULL && !kmem_move_noreap) {
3106 		kmem_cache_defrag(cp);
3107 	}
3108 }
3109 
3110 static void
kmem_reap_timeout(void * flag_arg)3111 kmem_reap_timeout(void *flag_arg)
3112 {
3113 	uint32_t *flag = (uint32_t *)flag_arg;
3114 
3115 	ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3116 	*flag = 0;
3117 }
3118 
3119 static void
kmem_reap_done(void * flag)3120 kmem_reap_done(void *flag)
3121 {
3122 	if (!callout_init_done) {
3123 		/* can't schedule a timeout at this point */
3124 		kmem_reap_timeout(flag);
3125 	} else {
3126 		(void) timeout(kmem_reap_timeout, flag, kmem_reap_interval);
3127 	}
3128 }
3129 
3130 static void
kmem_reap_start(void * flag)3131 kmem_reap_start(void *flag)
3132 {
3133 	ASSERT(flag == &kmem_reaping || flag == &kmem_reaping_idspace);
3134 
3135 	if (flag == &kmem_reaping) {
3136 		kmem_cache_applyall(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3137 		/*
3138 		 * if we have segkp under heap, reap segkp cache.
3139 		 */
3140 		if (segkp_fromheap)
3141 			segkp_cache_free();
3142 	}
3143 	else
3144 		kmem_cache_applyall_id(kmem_cache_reap, kmem_taskq, TQ_NOSLEEP);
3145 
3146 	/*
3147 	 * We use taskq_dispatch() to schedule a timeout to clear
3148 	 * the flag so that kmem_reap() becomes self-throttling:
3149 	 * we won't reap again until the current reap completes *and*
3150 	 * at least kmem_reap_interval ticks have elapsed.
3151 	 */
3152 	if (taskq_dispatch(kmem_taskq, kmem_reap_done, flag, TQ_NOSLEEP) ==
3153 	    TASKQID_INVALID)
3154 		kmem_reap_done(flag);
3155 }
3156 
3157 static void
kmem_reap_common(void * flag_arg)3158 kmem_reap_common(void *flag_arg)
3159 {
3160 	uint32_t *flag = (uint32_t *)flag_arg;
3161 
3162 	if (MUTEX_HELD(&kmem_cache_lock) || kmem_taskq == NULL ||
3163 	    atomic_cas_32(flag, 0, 1) != 0)
3164 		return;
3165 
3166 	/*
3167 	 * It may not be kosher to do memory allocation when a reap is called
3168 	 * (for example, if vmem_populate() is in the call chain).  So we
3169 	 * start the reap going with a TQ_NOALLOC dispatch.  If the dispatch
3170 	 * fails, we reset the flag, and the next reap will try again.
3171 	 */
3172 	if (taskq_dispatch(kmem_taskq, kmem_reap_start, flag, TQ_NOALLOC) ==
3173 	    TASKQID_INVALID)
3174 		*flag = 0;
3175 }
3176 
3177 /*
3178  * Reclaim all unused memory from all caches.  Called from the VM system
3179  * when memory gets tight.
3180  */
3181 void
kmem_reap(void)3182 kmem_reap(void)
3183 {
3184 	kmem_reap_common(&kmem_reaping);
3185 }
3186 
3187 /*
3188  * Reclaim all unused memory from identifier arenas, called when a vmem
3189  * arena not back by memory is exhausted.  Since reaping memory-backed caches
3190  * cannot help with identifier exhaustion, we avoid both a large amount of
3191  * work and unwanted side-effects from reclaim callbacks.
3192  */
3193 void
kmem_reap_idspace(void)3194 kmem_reap_idspace(void)
3195 {
3196 	kmem_reap_common(&kmem_reaping_idspace);
3197 }
3198 
3199 /*
3200  * Purge all magazines from a cache and set its magazine limit to zero.
3201  * All calls are serialized by the kmem_taskq lock, except for the final
3202  * call from kmem_cache_destroy().
3203  */
3204 static void
kmem_cache_magazine_purge(kmem_cache_t * cp)3205 kmem_cache_magazine_purge(kmem_cache_t *cp)
3206 {
3207 	kmem_cpu_cache_t *ccp;
3208 	kmem_magazine_t *mp, *pmp;
3209 	int rounds, prounds, cpu_seqid;
3210 
3211 	ASSERT(!list_link_active(&cp->cache_link) ||
3212 	    taskq_member(kmem_taskq, curthread));
3213 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
3214 
3215 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3216 		ccp = &cp->cache_cpu[cpu_seqid];
3217 
3218 		mutex_enter(&ccp->cc_lock);
3219 		mp = ccp->cc_loaded;
3220 		pmp = ccp->cc_ploaded;
3221 		rounds = ccp->cc_rounds;
3222 		prounds = ccp->cc_prounds;
3223 		ccp->cc_loaded = NULL;
3224 		ccp->cc_ploaded = NULL;
3225 		ccp->cc_rounds = -1;
3226 		ccp->cc_prounds = -1;
3227 		ccp->cc_magsize = 0;
3228 		mutex_exit(&ccp->cc_lock);
3229 
3230 		if (mp)
3231 			kmem_magazine_destroy(cp, mp, rounds);
3232 		if (pmp)
3233 			kmem_magazine_destroy(cp, pmp, prounds);
3234 	}
3235 
3236 	kmem_depot_ws_zero(cp);
3237 	kmem_depot_ws_reap(cp);
3238 }
3239 
3240 /*
3241  * Enable per-cpu magazines on a cache.
3242  */
3243 static void
kmem_cache_magazine_enable(kmem_cache_t * cp)3244 kmem_cache_magazine_enable(kmem_cache_t *cp)
3245 {
3246 	int cpu_seqid;
3247 
3248 	if (cp->cache_flags & KMF_NOMAGAZINE)
3249 		return;
3250 
3251 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3252 		kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3253 		mutex_enter(&ccp->cc_lock);
3254 		ccp->cc_magsize = cp->cache_magtype->mt_magsize;
3255 		mutex_exit(&ccp->cc_lock);
3256 	}
3257 
3258 }
3259 
3260 /*
3261  * Allow our caller to determine if there are running reaps.
3262  *
3263  * This call is very conservative and may return B_TRUE even when
3264  * reaping activity isn't active. If it returns B_FALSE, then reaping
3265  * activity is definitely inactive.
3266  */
3267 boolean_t
kmem_cache_reap_active(void)3268 kmem_cache_reap_active(void)
3269 {
3270 	return (!taskq_empty(kmem_taskq));
3271 }
3272 
3273 /*
3274  * Reap (almost) everything soon.
3275  *
3276  * Note: this does not wait for the reap-tasks to complete. Caller
3277  * should use kmem_cache_reap_active() (above) and/or moderation to
3278  * avoid scheduling too many reap-tasks.
3279  */
3280 void
kmem_cache_reap_soon(kmem_cache_t * cp)3281 kmem_cache_reap_soon(kmem_cache_t *cp)
3282 {
3283 	ASSERT(list_link_active(&cp->cache_link));
3284 
3285 	kmem_depot_ws_zero(cp);
3286 
3287 	(void) taskq_dispatch(kmem_taskq,
3288 	    (task_func_t *)kmem_depot_ws_reap, cp, TQ_SLEEP);
3289 }
3290 
3291 /*
3292  * Recompute a cache's magazine size.  The trade-off is that larger magazines
3293  * provide a higher transfer rate with the depot, while smaller magazines
3294  * reduce memory consumption.  Magazine resizing is an expensive operation;
3295  * it should not be done frequently.
3296  *
3297  * Changes to the magazine size are serialized by the kmem_taskq lock.
3298  *
3299  * Note: at present this only grows the magazine size.  It might be useful
3300  * to allow shrinkage too.
3301  */
3302 static void
kmem_cache_magazine_resize(kmem_cache_t * cp)3303 kmem_cache_magazine_resize(kmem_cache_t *cp)
3304 {
3305 	kmem_magtype_t *mtp = cp->cache_magtype;
3306 
3307 	ASSERT(taskq_member(kmem_taskq, curthread));
3308 
3309 	if (cp->cache_chunksize < mtp->mt_maxbuf) {
3310 		kmem_cache_magazine_purge(cp);
3311 		mutex_enter(&cp->cache_depot_lock);
3312 		cp->cache_magtype = ++mtp;
3313 		cp->cache_depot_contention_prev =
3314 		    cp->cache_depot_contention + INT_MAX;
3315 		mutex_exit(&cp->cache_depot_lock);
3316 		kmem_cache_magazine_enable(cp);
3317 	}
3318 }
3319 
3320 /*
3321  * Rescale a cache's hash table, so that the table size is roughly the
3322  * cache size.  We want the average lookup time to be extremely small.
3323  */
3324 static void
kmem_hash_rescale(kmem_cache_t * cp)3325 kmem_hash_rescale(kmem_cache_t *cp)
3326 {
3327 	kmem_bufctl_t **old_table, **new_table, *bcp;
3328 	size_t old_size, new_size, h;
3329 
3330 	ASSERT(taskq_member(kmem_taskq, curthread));
3331 
3332 	new_size = MAX(KMEM_HASH_INITIAL,
3333 	    1 << (highbit(3 * cp->cache_buftotal + 4) - 2));
3334 	old_size = cp->cache_hash_mask + 1;
3335 
3336 	if ((old_size >> 1) <= new_size && new_size <= (old_size << 1))
3337 		return;
3338 
3339 	new_table = vmem_alloc(kmem_hash_arena, new_size * sizeof (void *),
3340 	    VM_NOSLEEP);
3341 	if (new_table == NULL)
3342 		return;
3343 	bzero(new_table, new_size * sizeof (void *));
3344 
3345 	mutex_enter(&cp->cache_lock);
3346 
3347 	old_size = cp->cache_hash_mask + 1;
3348 	old_table = cp->cache_hash_table;
3349 
3350 	cp->cache_hash_mask = new_size - 1;
3351 	cp->cache_hash_table = new_table;
3352 	cp->cache_rescale++;
3353 
3354 	for (h = 0; h < old_size; h++) {
3355 		bcp = old_table[h];
3356 		while (bcp != NULL) {
3357 			void *addr = bcp->bc_addr;
3358 			kmem_bufctl_t *next_bcp = bcp->bc_next;
3359 			kmem_bufctl_t **hash_bucket = KMEM_HASH(cp, addr);
3360 			bcp->bc_next = *hash_bucket;
3361 			*hash_bucket = bcp;
3362 			bcp = next_bcp;
3363 		}
3364 	}
3365 
3366 	mutex_exit(&cp->cache_lock);
3367 
3368 	vmem_free(kmem_hash_arena, old_table, old_size * sizeof (void *));
3369 }
3370 
3371 /*
3372  * Perform periodic maintenance on a cache: hash rescaling, depot working-set
3373  * update, magazine resizing, and slab consolidation.
3374  */
3375 static void
kmem_cache_update(kmem_cache_t * cp)3376 kmem_cache_update(kmem_cache_t *cp)
3377 {
3378 	int need_hash_rescale = 0;
3379 	int need_magazine_resize = 0;
3380 
3381 	ASSERT(MUTEX_HELD(&kmem_cache_lock));
3382 
3383 	/*
3384 	 * If the cache has become much larger or smaller than its hash table,
3385 	 * fire off a request to rescale the hash table.
3386 	 */
3387 	mutex_enter(&cp->cache_lock);
3388 
3389 	if ((cp->cache_flags & KMF_HASH) &&
3390 	    (cp->cache_buftotal > (cp->cache_hash_mask << 1) ||
3391 	    (cp->cache_buftotal < (cp->cache_hash_mask >> 1) &&
3392 	    cp->cache_hash_mask > KMEM_HASH_INITIAL)))
3393 		need_hash_rescale = 1;
3394 
3395 	mutex_exit(&cp->cache_lock);
3396 
3397 	/*
3398 	 * Update the depot working set statistics.
3399 	 */
3400 	kmem_depot_ws_update(cp);
3401 
3402 	/*
3403 	 * If there's a lot of contention in the depot,
3404 	 * increase the magazine size.
3405 	 */
3406 	mutex_enter(&cp->cache_depot_lock);
3407 
3408 	if (cp->cache_chunksize < cp->cache_magtype->mt_maxbuf &&
3409 	    (int)(cp->cache_depot_contention -
3410 	    cp->cache_depot_contention_prev) > kmem_depot_contention)
3411 		need_magazine_resize = 1;
3412 
3413 	cp->cache_depot_contention_prev = cp->cache_depot_contention;
3414 
3415 	mutex_exit(&cp->cache_depot_lock);
3416 
3417 	if (need_hash_rescale)
3418 		(void) taskq_dispatch(kmem_taskq,
3419 		    (task_func_t *)kmem_hash_rescale, cp, TQ_NOSLEEP);
3420 
3421 	if (need_magazine_resize)
3422 		(void) taskq_dispatch(kmem_taskq,
3423 		    (task_func_t *)kmem_cache_magazine_resize, cp, TQ_NOSLEEP);
3424 
3425 	if (cp->cache_defrag != NULL)
3426 		(void) taskq_dispatch(kmem_taskq,
3427 		    (task_func_t *)kmem_cache_scan, cp, TQ_NOSLEEP);
3428 }
3429 
3430 static void kmem_update(void *);
3431 
3432 static void
kmem_update_timeout(void * dummy)3433 kmem_update_timeout(void *dummy)
3434 {
3435 	(void) timeout(kmem_update, dummy, kmem_reap_interval);
3436 }
3437 
3438 static void
kmem_update(void * dummy)3439 kmem_update(void *dummy)
3440 {
3441 	kmem_cache_applyall(kmem_cache_update, NULL, TQ_NOSLEEP);
3442 
3443 	/*
3444 	 * We use taskq_dispatch() to reschedule the timeout so that
3445 	 * kmem_update() becomes self-throttling: it won't schedule
3446 	 * new tasks until all previous tasks have completed.
3447 	 */
3448 	if (taskq_dispatch(kmem_taskq, kmem_update_timeout, dummy, TQ_NOSLEEP)
3449 	    == TASKQID_INVALID)
3450 		kmem_update_timeout(NULL);
3451 }
3452 
3453 static int
kmem_cache_kstat_update(kstat_t * ksp,int rw)3454 kmem_cache_kstat_update(kstat_t *ksp, int rw)
3455 {
3456 	struct kmem_cache_kstat *kmcp = &kmem_cache_kstat;
3457 	kmem_cache_t *cp = ksp->ks_private;
3458 	uint64_t cpu_buf_avail;
3459 	uint64_t buf_avail = 0;
3460 	int cpu_seqid;
3461 	long reap;
3462 
3463 	ASSERT(MUTEX_HELD(&kmem_cache_kstat_lock));
3464 
3465 	if (rw == KSTAT_WRITE)
3466 		return (EACCES);
3467 
3468 	mutex_enter(&cp->cache_lock);
3469 
3470 	kmcp->kmc_alloc_fail.value.ui64		= cp->cache_alloc_fail;
3471 	kmcp->kmc_alloc.value.ui64		= cp->cache_slab_alloc;
3472 	kmcp->kmc_free.value.ui64		= cp->cache_slab_free;
3473 	kmcp->kmc_slab_alloc.value.ui64		= cp->cache_slab_alloc;
3474 	kmcp->kmc_slab_free.value.ui64		= cp->cache_slab_free;
3475 
3476 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3477 		kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3478 
3479 		mutex_enter(&ccp->cc_lock);
3480 
3481 		cpu_buf_avail = 0;
3482 		if (ccp->cc_rounds > 0)
3483 			cpu_buf_avail += ccp->cc_rounds;
3484 		if (ccp->cc_prounds > 0)
3485 			cpu_buf_avail += ccp->cc_prounds;
3486 
3487 		kmcp->kmc_alloc.value.ui64	+= ccp->cc_alloc;
3488 		kmcp->kmc_free.value.ui64	+= ccp->cc_free;
3489 		buf_avail			+= cpu_buf_avail;
3490 
3491 		mutex_exit(&ccp->cc_lock);
3492 	}
3493 
3494 	mutex_enter(&cp->cache_depot_lock);
3495 
3496 	kmcp->kmc_depot_alloc.value.ui64	= cp->cache_full.ml_alloc;
3497 	kmcp->kmc_depot_free.value.ui64		= cp->cache_empty.ml_alloc;
3498 	kmcp->kmc_depot_contention.value.ui64	= cp->cache_depot_contention;
3499 	kmcp->kmc_full_magazines.value.ui64	= cp->cache_full.ml_total;
3500 	kmcp->kmc_empty_magazines.value.ui64	= cp->cache_empty.ml_total;
3501 	kmcp->kmc_magazine_size.value.ui64	=
3502 	    (cp->cache_flags & KMF_NOMAGAZINE) ?
3503 	    0 : cp->cache_magtype->mt_magsize;
3504 
3505 	kmcp->kmc_alloc.value.ui64		+= cp->cache_full.ml_alloc;
3506 	kmcp->kmc_free.value.ui64		+= cp->cache_empty.ml_alloc;
3507 	buf_avail += cp->cache_full.ml_total * cp->cache_magtype->mt_magsize;
3508 
3509 	reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
3510 	reap = MIN(reap, cp->cache_full.ml_total);
3511 
3512 	mutex_exit(&cp->cache_depot_lock);
3513 
3514 	kmcp->kmc_buf_size.value.ui64	= cp->cache_bufsize;
3515 	kmcp->kmc_align.value.ui64	= cp->cache_align;
3516 	kmcp->kmc_chunk_size.value.ui64	= cp->cache_chunksize;
3517 	kmcp->kmc_slab_size.value.ui64	= cp->cache_slabsize;
3518 	kmcp->kmc_buf_constructed.value.ui64 = buf_avail;
3519 	buf_avail += cp->cache_bufslab;
3520 	kmcp->kmc_buf_avail.value.ui64	= buf_avail;
3521 	kmcp->kmc_buf_inuse.value.ui64	= cp->cache_buftotal - buf_avail;
3522 	kmcp->kmc_buf_total.value.ui64	= cp->cache_buftotal;
3523 	kmcp->kmc_buf_max.value.ui64	= cp->cache_bufmax;
3524 	kmcp->kmc_slab_create.value.ui64	= cp->cache_slab_create;
3525 	kmcp->kmc_slab_destroy.value.ui64	= cp->cache_slab_destroy;
3526 	kmcp->kmc_hash_size.value.ui64	= (cp->cache_flags & KMF_HASH) ?
3527 	    cp->cache_hash_mask + 1 : 0;
3528 	kmcp->kmc_hash_lookup_depth.value.ui64	= cp->cache_lookup_depth;
3529 	kmcp->kmc_hash_rescale.value.ui64	= cp->cache_rescale;
3530 	kmcp->kmc_vmem_source.value.ui64	= cp->cache_arena->vm_id;
3531 	kmcp->kmc_reap.value.ui64	= cp->cache_reap;
3532 
3533 	if (cp->cache_defrag == NULL) {
3534 		kmcp->kmc_move_callbacks.value.ui64	= 0;
3535 		kmcp->kmc_move_yes.value.ui64		= 0;
3536 		kmcp->kmc_move_no.value.ui64		= 0;
3537 		kmcp->kmc_move_later.value.ui64		= 0;
3538 		kmcp->kmc_move_dont_need.value.ui64	= 0;
3539 		kmcp->kmc_move_dont_know.value.ui64	= 0;
3540 		kmcp->kmc_move_hunt_found.value.ui64	= 0;
3541 		kmcp->kmc_move_slabs_freed.value.ui64	= 0;
3542 		kmcp->kmc_defrag.value.ui64		= 0;
3543 		kmcp->kmc_scan.value.ui64		= 0;
3544 		kmcp->kmc_move_reclaimable.value.ui64	= 0;
3545 	} else {
3546 		int64_t reclaimable;
3547 
3548 		kmem_defrag_t *kd = cp->cache_defrag;
3549 		kmcp->kmc_move_callbacks.value.ui64	= kd->kmd_callbacks;
3550 		kmcp->kmc_move_yes.value.ui64		= kd->kmd_yes;
3551 		kmcp->kmc_move_no.value.ui64		= kd->kmd_no;
3552 		kmcp->kmc_move_later.value.ui64		= kd->kmd_later;
3553 		kmcp->kmc_move_dont_need.value.ui64	= kd->kmd_dont_need;
3554 		kmcp->kmc_move_dont_know.value.ui64	= kd->kmd_dont_know;
3555 		kmcp->kmc_move_hunt_found.value.ui64	= 0;
3556 		kmcp->kmc_move_slabs_freed.value.ui64	= kd->kmd_slabs_freed;
3557 		kmcp->kmc_defrag.value.ui64		= kd->kmd_defrags;
3558 		kmcp->kmc_scan.value.ui64		= kd->kmd_scans;
3559 
3560 		reclaimable = cp->cache_bufslab - (cp->cache_maxchunks - 1);
3561 		reclaimable = MAX(reclaimable, 0);
3562 		reclaimable += ((uint64_t)reap * cp->cache_magtype->mt_magsize);
3563 		kmcp->kmc_move_reclaimable.value.ui64	= reclaimable;
3564 	}
3565 
3566 	mutex_exit(&cp->cache_lock);
3567 	return (0);
3568 }
3569 
3570 /*
3571  * Return a named statistic about a particular cache.
3572  * This shouldn't be called very often, so it's currently designed for
3573  * simplicity (leverages existing kstat support) rather than efficiency.
3574  */
3575 uint64_t
kmem_cache_stat(kmem_cache_t * cp,char * name)3576 kmem_cache_stat(kmem_cache_t *cp, char *name)
3577 {
3578 	int i;
3579 	kstat_t *ksp = cp->cache_kstat;
3580 	kstat_named_t *knp = (kstat_named_t *)&kmem_cache_kstat;
3581 	uint64_t value = 0;
3582 
3583 	if (ksp != NULL) {
3584 		mutex_enter(&kmem_cache_kstat_lock);
3585 		(void) kmem_cache_kstat_update(ksp, KSTAT_READ);
3586 		for (i = 0; i < ksp->ks_ndata; i++) {
3587 			if (strcmp(knp[i].name, name) == 0) {
3588 				value = knp[i].value.ui64;
3589 				break;
3590 			}
3591 		}
3592 		mutex_exit(&kmem_cache_kstat_lock);
3593 	}
3594 	return (value);
3595 }
3596 
3597 /*
3598  * Return an estimate of currently available kernel heap memory.
3599  * On 32-bit systems, physical memory may exceed virtual memory,
3600  * we just truncate the result at 1GB.
3601  */
3602 size_t
kmem_avail(void)3603 kmem_avail(void)
3604 {
3605 	spgcnt_t rmem = availrmem - tune.t_minarmem;
3606 	spgcnt_t fmem = freemem - minfree;
3607 
3608 	return ((size_t)ptob(MIN(MAX(MIN(rmem, fmem), 0),
3609 	    1 << (30 - PAGESHIFT))));
3610 }
3611 
3612 /*
3613  * Return the maximum amount of memory that is (in theory) allocatable
3614  * from the heap. This may be used as an estimate only since there
3615  * is no guarentee this space will still be available when an allocation
3616  * request is made, nor that the space may be allocated in one big request
3617  * due to kernel heap fragmentation.
3618  */
3619 size_t
kmem_maxavail(void)3620 kmem_maxavail(void)
3621 {
3622 	spgcnt_t pmem = availrmem - tune.t_minarmem;
3623 	spgcnt_t vmem = btop(vmem_size(heap_arena, VMEM_FREE));
3624 
3625 	return ((size_t)ptob(MAX(MIN(pmem, vmem), 0)));
3626 }
3627 
3628 /*
3629  * Indicate whether memory-intensive kmem debugging is enabled.
3630  */
3631 int
kmem_debugging(void)3632 kmem_debugging(void)
3633 {
3634 	return (kmem_flags & (KMF_AUDIT | KMF_REDZONE));
3635 }
3636 
3637 /* binning function, sorts finely at the two extremes */
3638 #define	KMEM_PARTIAL_SLAB_WEIGHT(sp, binshift)				\
3639 	((((sp)->slab_refcnt <= (binshift)) ||				\
3640 	    (((sp)->slab_chunks - (sp)->slab_refcnt) <= (binshift)))	\
3641 	    ? -(sp)->slab_refcnt					\
3642 	    : -((binshift) + ((sp)->slab_refcnt >> (binshift))))
3643 
3644 /*
3645  * Minimizing the number of partial slabs on the freelist minimizes
3646  * fragmentation (the ratio of unused buffers held by the slab layer). There are
3647  * two ways to get a slab off of the freelist: 1) free all the buffers on the
3648  * slab, and 2) allocate all the buffers on the slab. It follows that we want
3649  * the most-used slabs at the front of the list where they have the best chance
3650  * of being completely allocated, and the least-used slabs at a safe distance
3651  * from the front to improve the odds that the few remaining buffers will all be
3652  * freed before another allocation can tie up the slab. For that reason a slab
3653  * with a higher slab_refcnt sorts less than than a slab with a lower
3654  * slab_refcnt.
3655  *
3656  * However, if a slab has at least one buffer that is deemed unfreeable, we
3657  * would rather have that slab at the front of the list regardless of
3658  * slab_refcnt, since even one unfreeable buffer makes the entire slab
3659  * unfreeable. If the client returns KMEM_CBRC_NO in response to a cache_move()
3660  * callback, the slab is marked unfreeable for as long as it remains on the
3661  * freelist.
3662  */
3663 static int
kmem_partial_slab_cmp(const void * p0,const void * p1)3664 kmem_partial_slab_cmp(const void *p0, const void *p1)
3665 {
3666 	const kmem_cache_t *cp;
3667 	const kmem_slab_t *s0 = p0;
3668 	const kmem_slab_t *s1 = p1;
3669 	int w0, w1;
3670 	size_t binshift;
3671 
3672 	ASSERT(KMEM_SLAB_IS_PARTIAL(s0));
3673 	ASSERT(KMEM_SLAB_IS_PARTIAL(s1));
3674 	ASSERT(s0->slab_cache == s1->slab_cache);
3675 	cp = s1->slab_cache;
3676 	ASSERT(MUTEX_HELD(&cp->cache_lock));
3677 	binshift = cp->cache_partial_binshift;
3678 
3679 	/* weight of first slab */
3680 	w0 = KMEM_PARTIAL_SLAB_WEIGHT(s0, binshift);
3681 	if (s0->slab_flags & KMEM_SLAB_NOMOVE) {
3682 		w0 -= cp->cache_maxchunks;
3683 	}
3684 
3685 	/* weight of second slab */
3686 	w1 = KMEM_PARTIAL_SLAB_WEIGHT(s1, binshift);
3687 	if (s1->slab_flags & KMEM_SLAB_NOMOVE) {
3688 		w1 -= cp->cache_maxchunks;
3689 	}
3690 
3691 	if (w0 < w1)
3692 		return (-1);
3693 	if (w0 > w1)
3694 		return (1);
3695 
3696 	/* compare pointer values */
3697 	if ((uintptr_t)s0 < (uintptr_t)s1)
3698 		return (-1);
3699 	if ((uintptr_t)s0 > (uintptr_t)s1)
3700 		return (1);
3701 
3702 	return (0);
3703 }
3704 
3705 /*
3706  * It must be valid to call the destructor (if any) on a newly created object.
3707  * That is, the constructor (if any) must leave the object in a valid state for
3708  * the destructor.
3709  */
3710 kmem_cache_t *
kmem_cache_create(char * name,size_t bufsize,size_t align,int (* constructor)(void *,void *,int),void (* destructor)(void *,void *),void (* reclaim)(void *),void * private,vmem_t * vmp,int cflags)3711 kmem_cache_create(
3712 	char *name,		/* descriptive name for this cache */
3713 	size_t bufsize,		/* size of the objects it manages */
3714 	size_t align,		/* required object alignment */
3715 	int (*constructor)(void *, void *, int), /* object constructor */
3716 	void (*destructor)(void *, void *),	/* object destructor */
3717 	void (*reclaim)(void *), /* memory reclaim callback */
3718 	void *private,		/* pass-thru arg for constr/destr/reclaim */
3719 	vmem_t *vmp,		/* vmem source for slab allocation */
3720 	int cflags)		/* cache creation flags */
3721 {
3722 	int cpu_seqid;
3723 	size_t chunksize;
3724 	kmem_cache_t *cp;
3725 	kmem_magtype_t *mtp;
3726 	size_t csize = KMEM_CACHE_SIZE(max_ncpus);
3727 
3728 #ifdef	DEBUG
3729 	/*
3730 	 * Cache names should conform to the rules for valid C identifiers
3731 	 */
3732 	if (!strident_valid(name)) {
3733 		cmn_err(CE_CONT,
3734 		    "kmem_cache_create: '%s' is an invalid cache name\n"
3735 		    "cache names must conform to the rules for "
3736 		    "C identifiers\n", name);
3737 	}
3738 #endif	/* DEBUG */
3739 
3740 	if (vmp == NULL)
3741 		vmp = kmem_default_arena;
3742 
3743 	/*
3744 	 * If this kmem cache has an identifier vmem arena as its source, mark
3745 	 * it such to allow kmem_reap_idspace().
3746 	 */
3747 	ASSERT(!(cflags & KMC_IDENTIFIER));   /* consumer should not set this */
3748 	if (vmp->vm_cflags & VMC_IDENTIFIER)
3749 		cflags |= KMC_IDENTIFIER;
3750 
3751 	/*
3752 	 * Get a kmem_cache structure.  We arrange that cp->cache_cpu[]
3753 	 * is aligned on a KMEM_CPU_CACHE_SIZE boundary to prevent
3754 	 * false sharing of per-CPU data.
3755 	 */
3756 	cp = vmem_xalloc(kmem_cache_arena, csize, KMEM_CPU_CACHE_SIZE,
3757 	    P2NPHASE(csize, KMEM_CPU_CACHE_SIZE), 0, NULL, NULL, VM_SLEEP);
3758 	bzero(cp, csize);
3759 	list_link_init(&cp->cache_link);
3760 
3761 	if (align == 0)
3762 		align = KMEM_ALIGN;
3763 
3764 	/*
3765 	 * If we're not at least KMEM_ALIGN aligned, we can't use free
3766 	 * memory to hold bufctl information (because we can't safely
3767 	 * perform word loads and stores on it).
3768 	 */
3769 	if (align < KMEM_ALIGN)
3770 		cflags |= KMC_NOTOUCH;
3771 
3772 	if (!ISP2(align) || align > vmp->vm_quantum)
3773 		panic("kmem_cache_create: bad alignment %lu", align);
3774 
3775 	mutex_enter(&kmem_flags_lock);
3776 	if (kmem_flags & KMF_RANDOMIZE)
3777 		kmem_flags = (((kmem_flags | ~KMF_RANDOM) + 1) & KMF_RANDOM) |
3778 		    KMF_RANDOMIZE;
3779 	cp->cache_flags = (kmem_flags | cflags) & KMF_DEBUG;
3780 	mutex_exit(&kmem_flags_lock);
3781 
3782 	/*
3783 	 * Make sure all the various flags are reasonable.
3784 	 */
3785 	ASSERT(!(cflags & KMC_NOHASH) || !(cflags & KMC_NOTOUCH));
3786 
3787 	if (cp->cache_flags & KMF_LITE) {
3788 		if (bufsize >= kmem_lite_minsize &&
3789 		    align <= kmem_lite_maxalign &&
3790 		    P2PHASE(bufsize, kmem_lite_maxalign) != 0) {
3791 			cp->cache_flags |= KMF_BUFTAG;
3792 			cp->cache_flags &= ~(KMF_AUDIT | KMF_FIREWALL);
3793 		} else {
3794 			cp->cache_flags &= ~KMF_DEBUG;
3795 		}
3796 	}
3797 
3798 	if (cp->cache_flags & KMF_DEADBEEF)
3799 		cp->cache_flags |= KMF_REDZONE;
3800 
3801 	if ((cflags & KMC_QCACHE) && (cp->cache_flags & KMF_AUDIT))
3802 		cp->cache_flags |= KMF_NOMAGAZINE;
3803 
3804 	if (cflags & KMC_NODEBUG)
3805 		cp->cache_flags &= ~KMF_DEBUG;
3806 
3807 	if (cflags & KMC_NOTOUCH)
3808 		cp->cache_flags &= ~KMF_TOUCH;
3809 
3810 	if (cflags & KMC_PREFILL)
3811 		cp->cache_flags |= KMF_PREFILL;
3812 
3813 	if (cflags & KMC_NOHASH)
3814 		cp->cache_flags &= ~(KMF_AUDIT | KMF_FIREWALL);
3815 
3816 	if (cflags & KMC_NOMAGAZINE)
3817 		cp->cache_flags |= KMF_NOMAGAZINE;
3818 
3819 	if ((cp->cache_flags & KMF_AUDIT) && !(cflags & KMC_NOTOUCH))
3820 		cp->cache_flags |= KMF_REDZONE;
3821 
3822 	if (!(cp->cache_flags & KMF_AUDIT))
3823 		cp->cache_flags &= ~KMF_CONTENTS;
3824 
3825 	if ((cp->cache_flags & KMF_BUFTAG) && bufsize >= kmem_minfirewall &&
3826 	    !(cp->cache_flags & KMF_LITE) && !(cflags & KMC_NOHASH))
3827 		cp->cache_flags |= KMF_FIREWALL;
3828 
3829 	if (vmp != kmem_default_arena || kmem_firewall_arena == NULL)
3830 		cp->cache_flags &= ~KMF_FIREWALL;
3831 
3832 	if (cp->cache_flags & KMF_FIREWALL) {
3833 		cp->cache_flags &= ~KMF_BUFTAG;
3834 		cp->cache_flags |= KMF_NOMAGAZINE;
3835 		ASSERT(vmp == kmem_default_arena);
3836 		vmp = kmem_firewall_arena;
3837 	}
3838 
3839 	/*
3840 	 * Set cache properties.
3841 	 */
3842 	(void) strncpy(cp->cache_name, name, KMEM_CACHE_NAMELEN);
3843 	strident_canon(cp->cache_name, KMEM_CACHE_NAMELEN + 1);
3844 	cp->cache_bufsize = bufsize;
3845 	cp->cache_align = align;
3846 	cp->cache_constructor = constructor;
3847 	cp->cache_destructor = destructor;
3848 	cp->cache_reclaim = reclaim;
3849 	cp->cache_private = private;
3850 	cp->cache_arena = vmp;
3851 	cp->cache_cflags = cflags;
3852 
3853 	/*
3854 	 * Determine the chunk size.
3855 	 */
3856 	chunksize = bufsize;
3857 
3858 	if (align >= KMEM_ALIGN) {
3859 		chunksize = P2ROUNDUP(chunksize, KMEM_ALIGN);
3860 		cp->cache_bufctl = chunksize - KMEM_ALIGN;
3861 	}
3862 
3863 	if (cp->cache_flags & KMF_BUFTAG) {
3864 		cp->cache_bufctl = chunksize;
3865 		cp->cache_buftag = chunksize;
3866 		if (cp->cache_flags & KMF_LITE)
3867 			chunksize += KMEM_BUFTAG_LITE_SIZE(kmem_lite_count);
3868 		else
3869 			chunksize += sizeof (kmem_buftag_t);
3870 	}
3871 
3872 	if (cp->cache_flags & KMF_DEADBEEF) {
3873 		cp->cache_verify = MIN(cp->cache_buftag, kmem_maxverify);
3874 		if (cp->cache_flags & KMF_LITE)
3875 			cp->cache_verify = sizeof (uint64_t);
3876 	}
3877 
3878 	cp->cache_contents = MIN(cp->cache_bufctl, kmem_content_maxsave);
3879 
3880 	cp->cache_chunksize = chunksize = P2ROUNDUP(chunksize, align);
3881 
3882 	/*
3883 	 * Now that we know the chunk size, determine the optimal slab size.
3884 	 */
3885 	if (vmp == kmem_firewall_arena) {
3886 		cp->cache_slabsize = P2ROUNDUP(chunksize, vmp->vm_quantum);
3887 		cp->cache_mincolor = cp->cache_slabsize - chunksize;
3888 		cp->cache_maxcolor = cp->cache_mincolor;
3889 		cp->cache_flags |= KMF_HASH;
3890 		ASSERT(!(cp->cache_flags & KMF_BUFTAG));
3891 	} else if ((cflags & KMC_NOHASH) || (!(cflags & KMC_NOTOUCH) &&
3892 	    !(cp->cache_flags & KMF_AUDIT) &&
3893 	    chunksize < vmp->vm_quantum / KMEM_VOID_FRACTION)) {
3894 		cp->cache_slabsize = vmp->vm_quantum;
3895 		cp->cache_mincolor = 0;
3896 		cp->cache_maxcolor =
3897 		    (cp->cache_slabsize - sizeof (kmem_slab_t)) % chunksize;
3898 		ASSERT(chunksize + sizeof (kmem_slab_t) <= cp->cache_slabsize);
3899 		ASSERT(!(cp->cache_flags & KMF_AUDIT));
3900 	} else {
3901 		size_t chunks, bestfit, waste, slabsize;
3902 		size_t minwaste = LONG_MAX;
3903 
3904 		bestfit = 0;
3905 		for (chunks = 1; chunks <= KMEM_VOID_FRACTION; chunks++) {
3906 			slabsize = P2ROUNDUP(chunksize * chunks,
3907 			    vmp->vm_quantum);
3908 			chunks = slabsize / chunksize;
3909 			waste = (slabsize % chunksize) / chunks;
3910 			if (waste < minwaste) {
3911 				minwaste = waste;
3912 				bestfit = slabsize;
3913 			}
3914 		}
3915 		if (cflags & KMC_QCACHE)
3916 			bestfit = VMEM_QCACHE_SLABSIZE(vmp->vm_qcache_max);
3917 		cp->cache_slabsize = bestfit;
3918 		cp->cache_mincolor = 0;
3919 		cp->cache_maxcolor = bestfit % chunksize;
3920 		cp->cache_flags |= KMF_HASH;
3921 	}
3922 
3923 	cp->cache_maxchunks = (cp->cache_slabsize / cp->cache_chunksize);
3924 	cp->cache_partial_binshift = highbit(cp->cache_maxchunks / 16) + 1;
3925 
3926 	/*
3927 	 * Disallowing prefill when either the DEBUG or HASH flag is set or when
3928 	 * there is a constructor avoids some tricky issues with debug setup
3929 	 * that may be revisited later. We cannot allow prefill in a
3930 	 * metadata cache because of potential recursion.
3931 	 */
3932 	if (vmp == kmem_msb_arena ||
3933 	    cp->cache_flags & (KMF_HASH | KMF_BUFTAG) ||
3934 	    cp->cache_constructor != NULL)
3935 		cp->cache_flags &= ~KMF_PREFILL;
3936 
3937 	if (cp->cache_flags & KMF_HASH) {
3938 		ASSERT(!(cflags & KMC_NOHASH));
3939 		cp->cache_bufctl_cache = (cp->cache_flags & KMF_AUDIT) ?
3940 		    kmem_bufctl_audit_cache : kmem_bufctl_cache;
3941 	}
3942 
3943 	if (cp->cache_maxcolor >= vmp->vm_quantum)
3944 		cp->cache_maxcolor = vmp->vm_quantum - 1;
3945 
3946 	cp->cache_color = cp->cache_mincolor;
3947 
3948 	/*
3949 	 * Initialize the rest of the slab layer.
3950 	 */
3951 	mutex_init(&cp->cache_lock, NULL, MUTEX_DEFAULT, NULL);
3952 
3953 	avl_create(&cp->cache_partial_slabs, kmem_partial_slab_cmp,
3954 	    sizeof (kmem_slab_t), offsetof(kmem_slab_t, slab_link));
3955 	/* LINTED: E_TRUE_LOGICAL_EXPR */
3956 	ASSERT(sizeof (list_node_t) <= sizeof (avl_node_t));
3957 	/* reuse partial slab AVL linkage for complete slab list linkage */
3958 	list_create(&cp->cache_complete_slabs,
3959 	    sizeof (kmem_slab_t), offsetof(kmem_slab_t, slab_link));
3960 
3961 	if (cp->cache_flags & KMF_HASH) {
3962 		cp->cache_hash_table = vmem_alloc(kmem_hash_arena,
3963 		    KMEM_HASH_INITIAL * sizeof (void *), VM_SLEEP);
3964 		bzero(cp->cache_hash_table,
3965 		    KMEM_HASH_INITIAL * sizeof (void *));
3966 		cp->cache_hash_mask = KMEM_HASH_INITIAL - 1;
3967 		cp->cache_hash_shift = highbit((ulong_t)chunksize) - 1;
3968 	}
3969 
3970 	/*
3971 	 * Initialize the depot.
3972 	 */
3973 	mutex_init(&cp->cache_depot_lock, NULL, MUTEX_DEFAULT, NULL);
3974 
3975 	for (mtp = kmem_magtype; chunksize <= mtp->mt_minbuf; mtp++)
3976 		continue;
3977 
3978 	cp->cache_magtype = mtp;
3979 
3980 	/*
3981 	 * Initialize the CPU layer.
3982 	 */
3983 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++) {
3984 		kmem_cpu_cache_t *ccp = &cp->cache_cpu[cpu_seqid];
3985 		mutex_init(&ccp->cc_lock, NULL, MUTEX_DEFAULT, NULL);
3986 		ccp->cc_flags = cp->cache_flags;
3987 		ccp->cc_rounds = -1;
3988 		ccp->cc_prounds = -1;
3989 	}
3990 
3991 	/*
3992 	 * Create the cache's kstats.
3993 	 */
3994 	if ((cp->cache_kstat = kstat_create("unix", 0, cp->cache_name,
3995 	    "kmem_cache", KSTAT_TYPE_NAMED,
3996 	    sizeof (kmem_cache_kstat) / sizeof (kstat_named_t),
3997 	    KSTAT_FLAG_VIRTUAL)) != NULL) {
3998 		cp->cache_kstat->ks_data = &kmem_cache_kstat;
3999 		cp->cache_kstat->ks_update = kmem_cache_kstat_update;
4000 		cp->cache_kstat->ks_private = cp;
4001 		cp->cache_kstat->ks_lock = &kmem_cache_kstat_lock;
4002 		kstat_install(cp->cache_kstat);
4003 	}
4004 
4005 	/*
4006 	 * Add the cache to the global list.  This makes it visible
4007 	 * to kmem_update(), so the cache must be ready for business.
4008 	 */
4009 	mutex_enter(&kmem_cache_lock);
4010 	list_insert_tail(&kmem_caches, cp);
4011 	mutex_exit(&kmem_cache_lock);
4012 
4013 	if (kmem_ready)
4014 		kmem_cache_magazine_enable(cp);
4015 
4016 	return (cp);
4017 }
4018 
4019 static int
kmem_move_cmp(const void * buf,const void * p)4020 kmem_move_cmp(const void *buf, const void *p)
4021 {
4022 	const kmem_move_t *kmm = p;
4023 	uintptr_t v1 = (uintptr_t)buf;
4024 	uintptr_t v2 = (uintptr_t)kmm->kmm_from_buf;
4025 	return (v1 < v2 ? -1 : (v1 > v2 ? 1 : 0));
4026 }
4027 
4028 static void
kmem_reset_reclaim_threshold(kmem_defrag_t * kmd)4029 kmem_reset_reclaim_threshold(kmem_defrag_t *kmd)
4030 {
4031 	kmd->kmd_reclaim_numer = 1;
4032 }
4033 
4034 /*
4035  * Initially, when choosing candidate slabs for buffers to move, we want to be
4036  * very selective and take only slabs that are less than
4037  * (1 / KMEM_VOID_FRACTION) allocated. If we have difficulty finding candidate
4038  * slabs, then we raise the allocation ceiling incrementally. The reclaim
4039  * threshold is reset to (1 / KMEM_VOID_FRACTION) as soon as the cache is no
4040  * longer fragmented.
4041  */
4042 static void
kmem_adjust_reclaim_threshold(kmem_defrag_t * kmd,int direction)4043 kmem_adjust_reclaim_threshold(kmem_defrag_t *kmd, int direction)
4044 {
4045 	if (direction > 0) {
4046 		/* make it easier to find a candidate slab */
4047 		if (kmd->kmd_reclaim_numer < (KMEM_VOID_FRACTION - 1)) {
4048 			kmd->kmd_reclaim_numer++;
4049 		}
4050 	} else {
4051 		/* be more selective */
4052 		if (kmd->kmd_reclaim_numer > 1) {
4053 			kmd->kmd_reclaim_numer--;
4054 		}
4055 	}
4056 }
4057 
4058 void
kmem_cache_set_move(kmem_cache_t * cp,kmem_cbrc_t (* move)(void *,void *,size_t,void *))4059 kmem_cache_set_move(kmem_cache_t *cp,
4060     kmem_cbrc_t (*move)(void *, void *, size_t, void *))
4061 {
4062 	kmem_defrag_t *defrag;
4063 
4064 	ASSERT(move != NULL);
4065 	/*
4066 	 * The consolidator does not support NOTOUCH caches because kmem cannot
4067 	 * initialize their slabs with the 0xbaddcafe memory pattern, which sets
4068 	 * a low order bit usable by clients to distinguish uninitialized memory
4069 	 * from known objects (see kmem_slab_create).
4070 	 */
4071 	ASSERT(!(cp->cache_cflags & KMC_NOTOUCH));
4072 	ASSERT(!(cp->cache_cflags & KMC_IDENTIFIER));
4073 
4074 	/*
4075 	 * We should not be holding anyone's cache lock when calling
4076 	 * kmem_cache_alloc(), so allocate in all cases before acquiring the
4077 	 * lock.
4078 	 */
4079 	defrag = kmem_cache_alloc(kmem_defrag_cache, KM_SLEEP);
4080 
4081 	mutex_enter(&cp->cache_lock);
4082 
4083 	if (KMEM_IS_MOVABLE(cp)) {
4084 		if (cp->cache_move == NULL) {
4085 			ASSERT(cp->cache_slab_alloc == 0);
4086 
4087 			cp->cache_defrag = defrag;
4088 			defrag = NULL; /* nothing to free */
4089 			bzero(cp->cache_defrag, sizeof (kmem_defrag_t));
4090 			avl_create(&cp->cache_defrag->kmd_moves_pending,
4091 			    kmem_move_cmp, sizeof (kmem_move_t),
4092 			    offsetof(kmem_move_t, kmm_entry));
4093 			/* LINTED: E_TRUE_LOGICAL_EXPR */
4094 			ASSERT(sizeof (list_node_t) <= sizeof (avl_node_t));
4095 			/* reuse the slab's AVL linkage for deadlist linkage */
4096 			list_create(&cp->cache_defrag->kmd_deadlist,
4097 			    sizeof (kmem_slab_t),
4098 			    offsetof(kmem_slab_t, slab_link));
4099 			kmem_reset_reclaim_threshold(cp->cache_defrag);
4100 		}
4101 		cp->cache_move = move;
4102 	}
4103 
4104 	mutex_exit(&cp->cache_lock);
4105 
4106 	if (defrag != NULL) {
4107 		kmem_cache_free(kmem_defrag_cache, defrag); /* unused */
4108 	}
4109 }
4110 
4111 void
kmem_cache_destroy(kmem_cache_t * cp)4112 kmem_cache_destroy(kmem_cache_t *cp)
4113 {
4114 	int cpu_seqid;
4115 
4116 	/*
4117 	 * Remove the cache from the global cache list so that no one else
4118 	 * can schedule tasks on its behalf, wait for any pending tasks to
4119 	 * complete, purge the cache, and then destroy it.
4120 	 */
4121 	mutex_enter(&kmem_cache_lock);
4122 	list_remove(&kmem_caches, cp);
4123 	mutex_exit(&kmem_cache_lock);
4124 
4125 	if (kmem_taskq != NULL)
4126 		taskq_wait(kmem_taskq);
4127 
4128 	if (kmem_move_taskq != NULL && cp->cache_defrag != NULL)
4129 		taskq_wait(kmem_move_taskq);
4130 
4131 	kmem_cache_magazine_purge(cp);
4132 
4133 	mutex_enter(&cp->cache_lock);
4134 	if (cp->cache_buftotal != 0)
4135 		cmn_err(CE_WARN, "kmem_cache_destroy: '%s' (%p) not empty",
4136 		    cp->cache_name, (void *)cp);
4137 	if (cp->cache_defrag != NULL) {
4138 		avl_destroy(&cp->cache_defrag->kmd_moves_pending);
4139 		list_destroy(&cp->cache_defrag->kmd_deadlist);
4140 		kmem_cache_free(kmem_defrag_cache, cp->cache_defrag);
4141 		cp->cache_defrag = NULL;
4142 	}
4143 	/*
4144 	 * The cache is now dead.  There should be no further activity.  We
4145 	 * enforce this by setting land mines in the constructor, destructor,
4146 	 * reclaim, and move routines that induce a kernel text fault if
4147 	 * invoked.
4148 	 */
4149 	cp->cache_constructor = (int (*)(void *, void *, int))1;
4150 	cp->cache_destructor = (void (*)(void *, void *))2;
4151 	cp->cache_reclaim = (void (*)(void *))3;
4152 	cp->cache_move = (kmem_cbrc_t (*)(void *, void *, size_t, void *))4;
4153 	mutex_exit(&cp->cache_lock);
4154 
4155 	kstat_delete(cp->cache_kstat);
4156 
4157 	if (cp->cache_hash_table != NULL)
4158 		vmem_free(kmem_hash_arena, cp->cache_hash_table,
4159 		    (cp->cache_hash_mask + 1) * sizeof (void *));
4160 
4161 	for (cpu_seqid = 0; cpu_seqid < max_ncpus; cpu_seqid++)
4162 		mutex_destroy(&cp->cache_cpu[cpu_seqid].cc_lock);
4163 
4164 	mutex_destroy(&cp->cache_depot_lock);
4165 	mutex_destroy(&cp->cache_lock);
4166 
4167 	vmem_free(kmem_cache_arena, cp, KMEM_CACHE_SIZE(max_ncpus));
4168 }
4169 
4170 /*ARGSUSED*/
4171 static int
kmem_cpu_setup(cpu_setup_t what,int id,void * arg)4172 kmem_cpu_setup(cpu_setup_t what, int id, void *arg)
4173 {
4174 	ASSERT(MUTEX_HELD(&cpu_lock));
4175 	if (what == CPU_UNCONFIG) {
4176 		kmem_cache_applyall(kmem_cache_magazine_purge,
4177 		    kmem_taskq, TQ_SLEEP);
4178 		kmem_cache_applyall(kmem_cache_magazine_enable,
4179 		    kmem_taskq, TQ_SLEEP);
4180 	}
4181 	return (0);
4182 }
4183 
4184 static void
kmem_alloc_caches_create(const int * array,size_t count,kmem_cache_t ** alloc_table,size_t maxbuf,uint_t shift)4185 kmem_alloc_caches_create(const int *array, size_t count,
4186     kmem_cache_t **alloc_table, size_t maxbuf, uint_t shift)
4187 {
4188 	char name[KMEM_CACHE_NAMELEN + 1];
4189 	size_t table_unit = (1 << shift); /* range of one alloc_table entry */
4190 	size_t size = table_unit;
4191 	int i;
4192 
4193 	for (i = 0; i < count; i++) {
4194 		size_t cache_size = array[i];
4195 		size_t align = KMEM_ALIGN;
4196 		kmem_cache_t *cp;
4197 
4198 		/* if the table has an entry for maxbuf, we're done */
4199 		if (size > maxbuf)
4200 			break;
4201 
4202 		/* cache size must be a multiple of the table unit */
4203 		ASSERT(P2PHASE(cache_size, table_unit) == 0);
4204 
4205 		/*
4206 		 * If they allocate a multiple of the coherency granularity,
4207 		 * they get a coherency-granularity-aligned address.
4208 		 */
4209 		if (IS_P2ALIGNED(cache_size, 64))
4210 			align = 64;
4211 		if (IS_P2ALIGNED(cache_size, PAGESIZE))
4212 			align = PAGESIZE;
4213 		(void) snprintf(name, sizeof (name),
4214 		    "kmem_alloc_%lu", cache_size);
4215 		cp = kmem_cache_create(name, cache_size, align,
4216 		    NULL, NULL, NULL, NULL, NULL, KMC_KMEM_ALLOC);
4217 
4218 		while (size <= cache_size) {
4219 			alloc_table[(size - 1) >> shift] = cp;
4220 			size += table_unit;
4221 		}
4222 	}
4223 
4224 	ASSERT(size > maxbuf);		/* i.e. maxbuf <= max(cache_size) */
4225 }
4226 
4227 static void
kmem_cache_init(int pass,int use_large_pages)4228 kmem_cache_init(int pass, int use_large_pages)
4229 {
4230 	int i;
4231 	size_t maxbuf;
4232 	kmem_magtype_t *mtp;
4233 
4234 	for (i = 0; i < sizeof (kmem_magtype) / sizeof (*mtp); i++) {
4235 		char name[KMEM_CACHE_NAMELEN + 1];
4236 
4237 		mtp = &kmem_magtype[i];
4238 		(void) sprintf(name, "kmem_magazine_%d", mtp->mt_magsize);
4239 		mtp->mt_cache = kmem_cache_create(name,
4240 		    (mtp->mt_magsize + 1) * sizeof (void *),
4241 		    mtp->mt_align, NULL, NULL, NULL, NULL,
4242 		    kmem_msb_arena, KMC_NOHASH);
4243 	}
4244 
4245 	kmem_slab_cache = kmem_cache_create("kmem_slab_cache",
4246 	    sizeof (kmem_slab_t), 0, NULL, NULL, NULL, NULL,
4247 	    kmem_msb_arena, KMC_NOHASH);
4248 
4249 	kmem_bufctl_cache = kmem_cache_create("kmem_bufctl_cache",
4250 	    sizeof (kmem_bufctl_t), 0, NULL, NULL, NULL, NULL,
4251 	    kmem_msb_arena, KMC_NOHASH);
4252 
4253 	kmem_bufctl_audit_cache = kmem_cache_create("kmem_bufctl_audit_cache",
4254 	    sizeof (kmem_bufctl_audit_t), 0, NULL, NULL, NULL, NULL,
4255 	    kmem_msb_arena, KMC_NOHASH);
4256 
4257 	if (pass == 2) {
4258 		kmem_va_arena = vmem_create("kmem_va",
4259 		    NULL, 0, PAGESIZE,
4260 		    vmem_alloc, vmem_free, heap_arena,
4261 		    8 * PAGESIZE, VM_SLEEP);
4262 
4263 		if (use_large_pages) {
4264 			kmem_default_arena = vmem_xcreate("kmem_default",
4265 			    NULL, 0, PAGESIZE,
4266 			    segkmem_alloc_lp, segkmem_free_lp, kmem_va_arena,
4267 			    0, VMC_DUMPSAFE | VM_SLEEP);
4268 		} else {
4269 			kmem_default_arena = vmem_create("kmem_default",
4270 			    NULL, 0, PAGESIZE,
4271 			    segkmem_alloc, segkmem_free, kmem_va_arena,
4272 			    0, VMC_DUMPSAFE | VM_SLEEP);
4273 		}
4274 
4275 		/* Figure out what our maximum cache size is */
4276 		maxbuf = kmem_max_cached;
4277 		if (maxbuf <= KMEM_MAXBUF) {
4278 			maxbuf = 0;
4279 			kmem_max_cached = KMEM_MAXBUF;
4280 		} else {
4281 			size_t size = 0;
4282 			size_t max =
4283 			    sizeof (kmem_big_alloc_sizes) / sizeof (int);
4284 			/*
4285 			 * Round maxbuf up to an existing cache size.  If maxbuf
4286 			 * is larger than the largest cache, we truncate it to
4287 			 * the largest cache's size.
4288 			 */
4289 			for (i = 0; i < max; i++) {
4290 				size = kmem_big_alloc_sizes[i];
4291 				if (maxbuf <= size)
4292 					break;
4293 			}
4294 			kmem_max_cached = maxbuf = size;
4295 		}
4296 
4297 		/*
4298 		 * The big alloc table may not be completely overwritten, so
4299 		 * we clear out any stale cache pointers from the first pass.
4300 		 */
4301 		bzero(kmem_big_alloc_table, sizeof (kmem_big_alloc_table));
4302 	} else {
4303 		/*
4304 		 * During the first pass, the kmem_alloc_* caches
4305 		 * are treated as metadata.
4306 		 */
4307 		kmem_default_arena = kmem_msb_arena;
4308 		maxbuf = KMEM_BIG_MAXBUF_32BIT;
4309 	}
4310 
4311 	/*
4312 	 * Set up the default caches to back kmem_alloc()
4313 	 */
4314 	kmem_alloc_caches_create(
4315 	    kmem_alloc_sizes, sizeof (kmem_alloc_sizes) / sizeof (int),
4316 	    kmem_alloc_table, KMEM_MAXBUF, KMEM_ALIGN_SHIFT);
4317 
4318 	kmem_alloc_caches_create(
4319 	    kmem_big_alloc_sizes, sizeof (kmem_big_alloc_sizes) / sizeof (int),
4320 	    kmem_big_alloc_table, maxbuf, KMEM_BIG_SHIFT);
4321 
4322 	kmem_big_alloc_table_max = maxbuf >> KMEM_BIG_SHIFT;
4323 }
4324 
4325 void
kmem_init(void)4326 kmem_init(void)
4327 {
4328 	kmem_cache_t *cp;
4329 	int old_kmem_flags = kmem_flags;
4330 	int use_large_pages = 0;
4331 	size_t maxverify, minfirewall;
4332 
4333 	kstat_init();
4334 
4335 	/*
4336 	 * Don't do firewalled allocations if the heap is less than 1TB
4337 	 * (i.e. on a 32-bit kernel)
4338 	 * The resulting VM_NEXTFIT allocations would create too much
4339 	 * fragmentation in a small heap.
4340 	 */
4341 #if defined(_LP64)
4342 	maxverify = minfirewall = PAGESIZE / 2;
4343 #else
4344 	maxverify = minfirewall = ULONG_MAX;
4345 #endif
4346 
4347 	/* LINTED */
4348 	ASSERT(sizeof (kmem_cpu_cache_t) == KMEM_CPU_CACHE_SIZE);
4349 
4350 	list_create(&kmem_caches, sizeof (kmem_cache_t),
4351 	    offsetof(kmem_cache_t, cache_link));
4352 
4353 	kmem_metadata_arena = vmem_create("kmem_metadata", NULL, 0, PAGESIZE,
4354 	    vmem_alloc, vmem_free, heap_arena, 8 * PAGESIZE,
4355 	    VM_SLEEP | VMC_NO_QCACHE);
4356 
4357 	kmem_msb_arena = vmem_create("kmem_msb", NULL, 0,
4358 	    PAGESIZE, segkmem_alloc, segkmem_free, kmem_metadata_arena, 0,
4359 	    VMC_DUMPSAFE | VM_SLEEP);
4360 
4361 	kmem_cache_arena = vmem_create("kmem_cache", NULL, 0, KMEM_ALIGN,
4362 	    segkmem_alloc, segkmem_free, kmem_metadata_arena, 0, VM_SLEEP);
4363 
4364 	kmem_hash_arena = vmem_create("kmem_hash", NULL, 0, KMEM_ALIGN,
4365 	    segkmem_alloc, segkmem_free, kmem_metadata_arena, 0, VM_SLEEP);
4366 
4367 	kmem_log_arena = vmem_create("kmem_log", NULL, 0, KMEM_ALIGN,
4368 	    segkmem_alloc, segkmem_free, heap_arena, 0, VM_SLEEP);
4369 
4370 	kmem_firewall_va_arena = vmem_create("kmem_firewall_va",
4371 	    NULL, 0, PAGESIZE,
4372 	    kmem_firewall_va_alloc, kmem_firewall_va_free, heap_arena,
4373 	    0, VM_SLEEP);
4374 
4375 	kmem_firewall_arena = vmem_create("kmem_firewall", NULL, 0, PAGESIZE,
4376 	    segkmem_alloc, segkmem_free, kmem_firewall_va_arena, 0,
4377 	    VMC_DUMPSAFE | VM_SLEEP);
4378 
4379 	/* temporary oversize arena for mod_read_system_file */
4380 	kmem_oversize_arena = vmem_create("kmem_oversize", NULL, 0, PAGESIZE,
4381 	    segkmem_alloc, segkmem_free, heap_arena, 0, VM_SLEEP);
4382 
4383 	kmem_reap_interval = 15 * hz;
4384 
4385 	/*
4386 	 * Read /etc/system.  This is a chicken-and-egg problem because
4387 	 * kmem_flags may be set in /etc/system, but mod_read_system_file()
4388 	 * needs to use the allocator.  The simplest solution is to create
4389 	 * all the standard kmem caches, read /etc/system, destroy all the
4390 	 * caches we just created, and then create them all again in light
4391 	 * of the (possibly) new kmem_flags and other kmem tunables.
4392 	 */
4393 	kmem_cache_init(1, 0);
4394 
4395 	mod_read_system_file(boothowto & RB_ASKNAME);
4396 
4397 	while ((cp = list_tail(&kmem_caches)) != NULL)
4398 		kmem_cache_destroy(cp);
4399 
4400 	vmem_destroy(kmem_oversize_arena);
4401 
4402 	if (old_kmem_flags & KMF_STICKY)
4403 		kmem_flags = old_kmem_flags;
4404 
4405 	if (!(kmem_flags & KMF_AUDIT))
4406 		vmem_seg_size = offsetof(vmem_seg_t, vs_thread);
4407 
4408 	if (kmem_maxverify == 0)
4409 		kmem_maxverify = maxverify;
4410 
4411 	if (kmem_minfirewall == 0)
4412 		kmem_minfirewall = minfirewall;
4413 
4414 	/*
4415 	 * give segkmem a chance to figure out if we are using large pages
4416 	 * for the kernel heap
4417 	 */
4418 	use_large_pages = segkmem_lpsetup();
4419 
4420 	/*
4421 	 * To protect against corruption, we keep the actual number of callers
4422 	 * KMF_LITE records seperate from the tunable.  We arbitrarily clamp
4423 	 * to 16, since the overhead for small buffers quickly gets out of
4424 	 * hand.
4425 	 *
4426 	 * The real limit would depend on the needs of the largest KMC_NOHASH
4427 	 * cache.
4428 	 */
4429 	kmem_lite_count = MIN(MAX(0, kmem_lite_pcs), 16);
4430 	kmem_lite_pcs = kmem_lite_count;
4431 
4432 	/*
4433 	 * Normally, we firewall oversized allocations when possible, but
4434 	 * if we are using large pages for kernel memory, and we don't have
4435 	 * any non-LITE debugging flags set, we want to allocate oversized
4436 	 * buffers from large pages, and so skip the firewalling.
4437 	 */
4438 	if (use_large_pages &&
4439 	    ((kmem_flags & KMF_LITE) || !(kmem_flags & KMF_DEBUG))) {
4440 		kmem_oversize_arena = vmem_xcreate("kmem_oversize", NULL, 0,
4441 		    PAGESIZE, segkmem_alloc_lp, segkmem_free_lp, heap_arena,
4442 		    0, VMC_DUMPSAFE | VM_SLEEP);
4443 	} else {
4444 		kmem_oversize_arena = vmem_create("kmem_oversize",
4445 		    NULL, 0, PAGESIZE,
4446 		    segkmem_alloc, segkmem_free, kmem_minfirewall < ULONG_MAX?
4447 		    kmem_firewall_va_arena : heap_arena, 0, VMC_DUMPSAFE |
4448 		    VM_SLEEP);
4449 	}
4450 
4451 	kmem_cache_init(2, use_large_pages);
4452 
4453 	if (kmem_flags & (KMF_AUDIT | KMF_RANDOMIZE)) {
4454 		if (kmem_transaction_log_size == 0)
4455 			kmem_transaction_log_size = kmem_maxavail() / 50;
4456 		kmem_transaction_log = kmem_log_init(kmem_transaction_log_size);
4457 	}
4458 
4459 	if (kmem_flags & (KMF_CONTENTS | KMF_RANDOMIZE)) {
4460 		if (kmem_content_log_size == 0)
4461 			kmem_content_log_size = kmem_maxavail() / 50;
4462 		kmem_content_log = kmem_log_init(kmem_content_log_size);
4463 	}
4464 
4465 	kmem_failure_log = kmem_log_init(kmem_failure_log_size);
4466 	kmem_slab_log = kmem_log_init(kmem_slab_log_size);
4467 	kmem_zerosized_log = kmem_log_init(kmem_zerosized_log_size);
4468 
4469 	/*
4470 	 * Initialize STREAMS message caches so allocb() is available.
4471 	 * This allows us to initialize the logging framework (cmn_err(9F),
4472 	 * strlog(9F), etc) so we can start recording messages.
4473 	 */
4474 	streams_msg_init();
4475 
4476 	/*
4477 	 * Initialize the ZSD framework in Zones so modules loaded henceforth
4478 	 * can register their callbacks.
4479 	 */
4480 	zone_zsd_init();
4481 
4482 	log_init();
4483 	taskq_init();
4484 
4485 	/*
4486 	 * Warn about invalid or dangerous values of kmem_flags.
4487 	 * Always warn about unsupported values.
4488 	 */
4489 	if (((kmem_flags & ~(KMF_AUDIT | KMF_DEADBEEF | KMF_REDZONE |
4490 	    KMF_CONTENTS | KMF_LITE)) != 0) ||
4491 	    ((kmem_flags & KMF_LITE) && kmem_flags != KMF_LITE))
4492 		cmn_err(CE_WARN, "kmem_flags set to unsupported value 0x%x.",
4493 		    kmem_flags);
4494 
4495 #ifdef DEBUG
4496 	if ((kmem_flags & KMF_DEBUG) == 0)
4497 		cmn_err(CE_NOTE, "kmem debugging disabled.");
4498 #else
4499 	/*
4500 	 * For non-debug kernels, the only "normal" flags are 0, KMF_LITE,
4501 	 * KMF_REDZONE, and KMF_CONTENTS (the last because it is only enabled
4502 	 * if KMF_AUDIT is set). We should warn the user about the performance
4503 	 * penalty of KMF_AUDIT or KMF_DEADBEEF if they are set and KMF_LITE
4504 	 * isn't set (since that disables AUDIT).
4505 	 */
4506 	if (!(kmem_flags & KMF_LITE) &&
4507 	    (kmem_flags & (KMF_AUDIT | KMF_DEADBEEF)) != 0)
4508 		cmn_err(CE_WARN, "High-overhead kmem debugging features "
4509 		    "enabled (kmem_flags = 0x%x).  Performance degradation "
4510 		    "and large memory overhead possible.", kmem_flags);
4511 #endif /* not DEBUG */
4512 
4513 	kmem_cache_applyall(kmem_cache_magazine_enable, NULL, TQ_SLEEP);
4514 
4515 	kmem_ready = 1;
4516 
4517 	/*
4518 	 * Initialize the platform-specific aligned/DMA memory allocator.
4519 	 */
4520 	ka_init();
4521 
4522 	/*
4523 	 * Initialize 32-bit ID cache.
4524 	 */
4525 	id32_init();
4526 
4527 	/*
4528 	 * Initialize the networking stack so modules loaded can
4529 	 * register their callbacks.
4530 	 */
4531 	netstack_init();
4532 }
4533 
4534 static void
kmem_move_init(void)4535 kmem_move_init(void)
4536 {
4537 	kmem_defrag_cache = kmem_cache_create("kmem_defrag_cache",
4538 	    sizeof (kmem_defrag_t), 0, NULL, NULL, NULL, NULL,
4539 	    kmem_msb_arena, KMC_NOHASH);
4540 	kmem_move_cache = kmem_cache_create("kmem_move_cache",
4541 	    sizeof (kmem_move_t), 0, NULL, NULL, NULL, NULL,
4542 	    kmem_msb_arena, KMC_NOHASH);
4543 
4544 	/*
4545 	 * kmem guarantees that move callbacks are sequential and that even
4546 	 * across multiple caches no two moves ever execute simultaneously.
4547 	 * Move callbacks are processed on a separate taskq so that client code
4548 	 * does not interfere with internal maintenance tasks.
4549 	 */
4550 	kmem_move_taskq = taskq_create_instance("kmem_move_taskq", 0, 1,
4551 	    minclsyspri, 100, INT_MAX, TASKQ_PREPOPULATE);
4552 }
4553 
4554 void
kmem_thread_init(void)4555 kmem_thread_init(void)
4556 {
4557 	kmem_move_init();
4558 
4559 	/*
4560 	 * This taskq is used for various kmem maintenance functions, including
4561 	 * kmem_reap().   When maintenance is required on every cache,
4562 	 * kmem_cache_applyall() dispatches one task per cache onto this queue.
4563 	 *
4564 	 * In the case of kmem_reap(), the system may be under increasingly
4565 	 * dire memory pressure and may not be able to allocate a new task
4566 	 * entry.  The count of entries to prepopulate (below) should cover at
4567 	 * least as many caches as we generally expect to exist on the system
4568 	 * so that they may all be scheduled for reaping under those
4569 	 * conditions.
4570 	 */
4571 	kmem_taskq = taskq_create_instance("kmem_taskq", 0, 1, minclsyspri,
4572 	    600, INT_MAX, TASKQ_PREPOPULATE);
4573 }
4574 
4575 void
kmem_mp_init(void)4576 kmem_mp_init(void)
4577 {
4578 	mutex_enter(&cpu_lock);
4579 	register_cpu_setup_func(kmem_cpu_setup, NULL);
4580 	mutex_exit(&cpu_lock);
4581 
4582 	kmem_update_timeout(NULL);
4583 
4584 	taskq_mp_init();
4585 }
4586 
4587 /*
4588  * Return the slab of the allocated buffer, or NULL if the buffer is not
4589  * allocated. This function may be called with a known slab address to determine
4590  * whether or not the buffer is allocated, or with a NULL slab address to obtain
4591  * an allocated buffer's slab.
4592  */
4593 static kmem_slab_t *
kmem_slab_allocated(kmem_cache_t * cp,kmem_slab_t * sp,void * buf)4594 kmem_slab_allocated(kmem_cache_t *cp, kmem_slab_t *sp, void *buf)
4595 {
4596 	kmem_bufctl_t *bcp, *bufbcp;
4597 
4598 	ASSERT(MUTEX_HELD(&cp->cache_lock));
4599 	ASSERT(sp == NULL || KMEM_SLAB_MEMBER(sp, buf));
4600 
4601 	if (cp->cache_flags & KMF_HASH) {
4602 		for (bcp = *KMEM_HASH(cp, buf);
4603 		    (bcp != NULL) && (bcp->bc_addr != buf);
4604 		    bcp = bcp->bc_next) {
4605 			continue;
4606 		}
4607 		ASSERT(sp != NULL && bcp != NULL ? sp == bcp->bc_slab : 1);
4608 		return (bcp == NULL ? NULL : bcp->bc_slab);
4609 	}
4610 
4611 	if (sp == NULL) {
4612 		sp = KMEM_SLAB(cp, buf);
4613 	}
4614 	bufbcp = KMEM_BUFCTL(cp, buf);
4615 	for (bcp = sp->slab_head;
4616 	    (bcp != NULL) && (bcp != bufbcp);
4617 	    bcp = bcp->bc_next) {
4618 		continue;
4619 	}
4620 	return (bcp == NULL ? sp : NULL);
4621 }
4622 
4623 static boolean_t
kmem_slab_is_reclaimable(kmem_cache_t * cp,kmem_slab_t * sp,int flags)4624 kmem_slab_is_reclaimable(kmem_cache_t *cp, kmem_slab_t *sp, int flags)
4625 {
4626 	long refcnt = sp->slab_refcnt;
4627 
4628 	ASSERT(cp->cache_defrag != NULL);
4629 
4630 	/*
4631 	 * For code coverage we want to be able to move an object within the
4632 	 * same slab (the only partial slab) even if allocating the destination
4633 	 * buffer resulted in a completely allocated slab.
4634 	 */
4635 	if (flags & KMM_DEBUG) {
4636 		return ((flags & KMM_DESPERATE) ||
4637 		    ((sp->slab_flags & KMEM_SLAB_NOMOVE) == 0));
4638 	}
4639 
4640 	/* If we're desperate, we don't care if the client said NO. */
4641 	if (flags & KMM_DESPERATE) {
4642 		return (refcnt < sp->slab_chunks); /* any partial */
4643 	}
4644 
4645 	if (sp->slab_flags & KMEM_SLAB_NOMOVE) {
4646 		return (B_FALSE);
4647 	}
4648 
4649 	if ((refcnt == 1) || kmem_move_any_partial) {
4650 		return (refcnt < sp->slab_chunks);
4651 	}
4652 
4653 	/*
4654 	 * The reclaim threshold is adjusted at each kmem_cache_scan() so that
4655 	 * slabs with a progressively higher percentage of used buffers can be
4656 	 * reclaimed until the cache as a whole is no longer fragmented.
4657 	 *
4658 	 *	sp->slab_refcnt   kmd_reclaim_numer
4659 	 *	--------------- < ------------------
4660 	 *	sp->slab_chunks   KMEM_VOID_FRACTION
4661 	 */
4662 	return ((refcnt * KMEM_VOID_FRACTION) <
4663 	    (sp->slab_chunks * cp->cache_defrag->kmd_reclaim_numer));
4664 }
4665 
4666 /*
4667  * May be called from the kmem_move_taskq, from kmem_cache_move_notify_task(),
4668  * or when the buffer is freed.
4669  */
4670 static void
kmem_slab_move_yes(kmem_cache_t * cp,kmem_slab_t * sp,void * from_buf)4671 kmem_slab_move_yes(kmem_cache_t *cp, kmem_slab_t *sp, void *from_buf)
4672 {
4673 	ASSERT(MUTEX_HELD(&cp->cache_lock));
4674 	ASSERT(KMEM_SLAB_MEMBER(sp, from_buf));
4675 
4676 	if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4677 		return;
4678 	}
4679 
4680 	if (sp->slab_flags & KMEM_SLAB_NOMOVE) {
4681 		if (KMEM_SLAB_OFFSET(sp, from_buf) == sp->slab_stuck_offset) {
4682 			avl_remove(&cp->cache_partial_slabs, sp);
4683 			sp->slab_flags &= ~KMEM_SLAB_NOMOVE;
4684 			sp->slab_stuck_offset = (uint32_t)-1;
4685 			avl_add(&cp->cache_partial_slabs, sp);
4686 		}
4687 	} else {
4688 		sp->slab_later_count = 0;
4689 		sp->slab_stuck_offset = (uint32_t)-1;
4690 	}
4691 }
4692 
4693 static void
kmem_slab_move_no(kmem_cache_t * cp,kmem_slab_t * sp,void * from_buf)4694 kmem_slab_move_no(kmem_cache_t *cp, kmem_slab_t *sp, void *from_buf)
4695 {
4696 	ASSERT(taskq_member(kmem_move_taskq, curthread));
4697 	ASSERT(MUTEX_HELD(&cp->cache_lock));
4698 	ASSERT(KMEM_SLAB_MEMBER(sp, from_buf));
4699 
4700 	if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4701 		return;
4702 	}
4703 
4704 	avl_remove(&cp->cache_partial_slabs, sp);
4705 	sp->slab_later_count = 0;
4706 	sp->slab_flags |= KMEM_SLAB_NOMOVE;
4707 	sp->slab_stuck_offset = KMEM_SLAB_OFFSET(sp, from_buf);
4708 	avl_add(&cp->cache_partial_slabs, sp);
4709 }
4710 
4711 static void kmem_move_end(kmem_cache_t *, kmem_move_t *);
4712 
4713 /*
4714  * The move callback takes two buffer addresses, the buffer to be moved, and a
4715  * newly allocated and constructed buffer selected by kmem as the destination.
4716  * It also takes the size of the buffer and an optional user argument specified
4717  * at cache creation time. kmem guarantees that the buffer to be moved has not
4718  * been unmapped by the virtual memory subsystem. Beyond that, it cannot
4719  * guarantee the present whereabouts of the buffer to be moved, so it is up to
4720  * the client to safely determine whether or not it is still using the buffer.
4721  * The client must not free either of the buffers passed to the move callback,
4722  * since kmem wants to free them directly to the slab layer. The client response
4723  * tells kmem which of the two buffers to free:
4724  *
4725  * YES		kmem frees the old buffer (the move was successful)
4726  * NO		kmem frees the new buffer, marks the slab of the old buffer
4727  *              non-reclaimable to avoid bothering the client again
4728  * LATER	kmem frees the new buffer, increments slab_later_count
4729  * DONT_KNOW	kmem frees the new buffer
4730  * DONT_NEED	kmem frees both the old buffer and the new buffer
4731  *
4732  * The pending callback argument now being processed contains both of the
4733  * buffers (old and new) passed to the move callback function, the slab of the
4734  * old buffer, and flags related to the move request, such as whether or not the
4735  * system was desperate for memory.
4736  *
4737  * Slabs are not freed while there is a pending callback, but instead are kept
4738  * on a deadlist, which is drained after the last callback completes. This means
4739  * that slabs are safe to access until kmem_move_end(), no matter how many of
4740  * their buffers have been freed. Once slab_refcnt reaches zero, it stays at
4741  * zero for as long as the slab remains on the deadlist and until the slab is
4742  * freed.
4743  */
4744 static void
kmem_move_buffer(kmem_move_t * callback)4745 kmem_move_buffer(kmem_move_t *callback)
4746 {
4747 	kmem_cbrc_t response;
4748 	kmem_slab_t *sp = callback->kmm_from_slab;
4749 	kmem_cache_t *cp = sp->slab_cache;
4750 	boolean_t free_on_slab;
4751 
4752 	ASSERT(taskq_member(kmem_move_taskq, curthread));
4753 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4754 	ASSERT(KMEM_SLAB_MEMBER(sp, callback->kmm_from_buf));
4755 
4756 	/*
4757 	 * The number of allocated buffers on the slab may have changed since we
4758 	 * last checked the slab's reclaimability (when the pending move was
4759 	 * enqueued), or the client may have responded NO when asked to move
4760 	 * another buffer on the same slab.
4761 	 */
4762 	if (!kmem_slab_is_reclaimable(cp, sp, callback->kmm_flags)) {
4763 		kmem_slab_free(cp, callback->kmm_to_buf);
4764 		kmem_move_end(cp, callback);
4765 		return;
4766 	}
4767 
4768 	/*
4769 	 * Checking the slab layer is easy, so we might as well do that here
4770 	 * in case we can avoid bothering the client.
4771 	 */
4772 	mutex_enter(&cp->cache_lock);
4773 	free_on_slab = (kmem_slab_allocated(cp, sp,
4774 	    callback->kmm_from_buf) == NULL);
4775 	mutex_exit(&cp->cache_lock);
4776 
4777 	if (free_on_slab) {
4778 		kmem_slab_free(cp, callback->kmm_to_buf);
4779 		kmem_move_end(cp, callback);
4780 		return;
4781 	}
4782 
4783 	if (cp->cache_flags & KMF_BUFTAG) {
4784 		/*
4785 		 * Make kmem_cache_alloc_debug() apply the constructor for us.
4786 		 */
4787 		if (kmem_cache_alloc_debug(cp, callback->kmm_to_buf,
4788 		    KM_NOSLEEP, 1, caller()) != 0) {
4789 			kmem_move_end(cp, callback);
4790 			return;
4791 		}
4792 	} else if (cp->cache_constructor != NULL &&
4793 	    cp->cache_constructor(callback->kmm_to_buf, cp->cache_private,
4794 	    KM_NOSLEEP) != 0) {
4795 		atomic_inc_64(&cp->cache_alloc_fail);
4796 		kmem_slab_free(cp, callback->kmm_to_buf);
4797 		kmem_move_end(cp, callback);
4798 		return;
4799 	}
4800 
4801 	cp->cache_defrag->kmd_callbacks++;
4802 	cp->cache_defrag->kmd_thread = curthread;
4803 	cp->cache_defrag->kmd_from_buf = callback->kmm_from_buf;
4804 	cp->cache_defrag->kmd_to_buf = callback->kmm_to_buf;
4805 	DTRACE_PROBE2(kmem__move__start, kmem_cache_t *, cp, kmem_move_t *,
4806 	    callback);
4807 
4808 	response = cp->cache_move(callback->kmm_from_buf,
4809 	    callback->kmm_to_buf, cp->cache_bufsize, cp->cache_private);
4810 
4811 	DTRACE_PROBE3(kmem__move__end, kmem_cache_t *, cp, kmem_move_t *,
4812 	    callback, kmem_cbrc_t, response);
4813 	cp->cache_defrag->kmd_thread = NULL;
4814 	cp->cache_defrag->kmd_from_buf = NULL;
4815 	cp->cache_defrag->kmd_to_buf = NULL;
4816 
4817 	if (response == KMEM_CBRC_YES) {
4818 		cp->cache_defrag->kmd_yes++;
4819 		kmem_slab_free_constructed(cp, callback->kmm_from_buf, B_FALSE);
4820 		/* slab safe to access until kmem_move_end() */
4821 		if (sp->slab_refcnt == 0)
4822 			cp->cache_defrag->kmd_slabs_freed++;
4823 		mutex_enter(&cp->cache_lock);
4824 		kmem_slab_move_yes(cp, sp, callback->kmm_from_buf);
4825 		mutex_exit(&cp->cache_lock);
4826 		kmem_move_end(cp, callback);
4827 		return;
4828 	}
4829 
4830 	switch (response) {
4831 	case KMEM_CBRC_NO:
4832 		cp->cache_defrag->kmd_no++;
4833 		mutex_enter(&cp->cache_lock);
4834 		kmem_slab_move_no(cp, sp, callback->kmm_from_buf);
4835 		mutex_exit(&cp->cache_lock);
4836 		break;
4837 	case KMEM_CBRC_LATER:
4838 		cp->cache_defrag->kmd_later++;
4839 		mutex_enter(&cp->cache_lock);
4840 		if (!KMEM_SLAB_IS_PARTIAL(sp)) {
4841 			mutex_exit(&cp->cache_lock);
4842 			break;
4843 		}
4844 
4845 		if (++sp->slab_later_count >= KMEM_DISBELIEF) {
4846 			kmem_slab_move_no(cp, sp, callback->kmm_from_buf);
4847 		} else if (!(sp->slab_flags & KMEM_SLAB_NOMOVE)) {
4848 			sp->slab_stuck_offset = KMEM_SLAB_OFFSET(sp,
4849 			    callback->kmm_from_buf);
4850 		}
4851 		mutex_exit(&cp->cache_lock);
4852 		break;
4853 	case KMEM_CBRC_DONT_NEED:
4854 		cp->cache_defrag->kmd_dont_need++;
4855 		kmem_slab_free_constructed(cp, callback->kmm_from_buf, B_FALSE);
4856 		if (sp->slab_refcnt == 0)
4857 			cp->cache_defrag->kmd_slabs_freed++;
4858 		mutex_enter(&cp->cache_lock);
4859 		kmem_slab_move_yes(cp, sp, callback->kmm_from_buf);
4860 		mutex_exit(&cp->cache_lock);
4861 		break;
4862 	case KMEM_CBRC_DONT_KNOW:
4863 		/*
4864 		 * If we don't know if we can move this buffer or not, we'll
4865 		 * just assume that we can't:  if the buffer is in fact free,
4866 		 * then it is sitting in one of the per-CPU magazines or in
4867 		 * a full magazine in the depot layer.  Either way, because
4868 		 * defrag is induced in the same logic that reaps a cache,
4869 		 * it's likely that full magazines will be returned to the
4870 		 * system soon (thereby accomplishing what we're trying to
4871 		 * accomplish here: return those magazines to their slabs).
4872 		 * Given this, any work that we might do now to locate a buffer
4873 		 * in a magazine is wasted (and expensive!) work; we bump
4874 		 * a counter in this case and otherwise assume that we can't
4875 		 * move it.
4876 		 */
4877 		cp->cache_defrag->kmd_dont_know++;
4878 		break;
4879 	default:
4880 		panic("'%s' (%p) unexpected move callback response %d\n",
4881 		    cp->cache_name, (void *)cp, response);
4882 	}
4883 
4884 	kmem_slab_free_constructed(cp, callback->kmm_to_buf, B_FALSE);
4885 	kmem_move_end(cp, callback);
4886 }
4887 
4888 /* Return B_FALSE if there is insufficient memory for the move request. */
4889 static boolean_t
kmem_move_begin(kmem_cache_t * cp,kmem_slab_t * sp,void * buf,int flags)4890 kmem_move_begin(kmem_cache_t *cp, kmem_slab_t *sp, void *buf, int flags)
4891 {
4892 	void *to_buf;
4893 	avl_index_t index;
4894 	kmem_move_t *callback, *pending;
4895 	ulong_t n;
4896 
4897 	ASSERT(taskq_member(kmem_taskq, curthread));
4898 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4899 	ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
4900 
4901 	callback = kmem_cache_alloc(kmem_move_cache, KM_NOSLEEP);
4902 
4903 	if (callback == NULL)
4904 		return (B_FALSE);
4905 
4906 	callback->kmm_from_slab = sp;
4907 	callback->kmm_from_buf = buf;
4908 	callback->kmm_flags = flags;
4909 
4910 	mutex_enter(&cp->cache_lock);
4911 
4912 	n = avl_numnodes(&cp->cache_partial_slabs);
4913 	if ((n == 0) || ((n == 1) && !(flags & KMM_DEBUG))) {
4914 		mutex_exit(&cp->cache_lock);
4915 		kmem_cache_free(kmem_move_cache, callback);
4916 		return (B_TRUE); /* there is no need for the move request */
4917 	}
4918 
4919 	pending = avl_find(&cp->cache_defrag->kmd_moves_pending, buf, &index);
4920 	if (pending != NULL) {
4921 		/*
4922 		 * If the move is already pending and we're desperate now,
4923 		 * update the move flags.
4924 		 */
4925 		if (flags & KMM_DESPERATE) {
4926 			pending->kmm_flags |= KMM_DESPERATE;
4927 		}
4928 		mutex_exit(&cp->cache_lock);
4929 		kmem_cache_free(kmem_move_cache, callback);
4930 		return (B_TRUE);
4931 	}
4932 
4933 	to_buf = kmem_slab_alloc_impl(cp, avl_first(&cp->cache_partial_slabs),
4934 	    B_FALSE);
4935 	callback->kmm_to_buf = to_buf;
4936 	avl_insert(&cp->cache_defrag->kmd_moves_pending, callback, index);
4937 
4938 	mutex_exit(&cp->cache_lock);
4939 
4940 	if (taskq_dispatch(kmem_move_taskq, (task_func_t *)kmem_move_buffer,
4941 	    callback, TQ_NOSLEEP) == TASKQID_INVALID) {
4942 		mutex_enter(&cp->cache_lock);
4943 		avl_remove(&cp->cache_defrag->kmd_moves_pending, callback);
4944 		mutex_exit(&cp->cache_lock);
4945 		kmem_slab_free(cp, to_buf);
4946 		kmem_cache_free(kmem_move_cache, callback);
4947 		return (B_FALSE);
4948 	}
4949 
4950 	return (B_TRUE);
4951 }
4952 
4953 static void
kmem_move_end(kmem_cache_t * cp,kmem_move_t * callback)4954 kmem_move_end(kmem_cache_t *cp, kmem_move_t *callback)
4955 {
4956 	avl_index_t index;
4957 
4958 	ASSERT(cp->cache_defrag != NULL);
4959 	ASSERT(taskq_member(kmem_move_taskq, curthread));
4960 	ASSERT(MUTEX_NOT_HELD(&cp->cache_lock));
4961 
4962 	mutex_enter(&cp->cache_lock);
4963 	VERIFY(avl_find(&cp->cache_defrag->kmd_moves_pending,
4964 	    callback->kmm_from_buf, &index) != NULL);
4965 	avl_remove(&cp->cache_defrag->kmd_moves_pending, callback);
4966 	if (avl_is_empty(&cp->cache_defrag->kmd_moves_pending)) {
4967 		list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
4968 		kmem_slab_t *sp;
4969 
4970 		/*
4971 		 * The last pending move completed. Release all slabs from the
4972 		 * front of the dead list except for any slab at the tail that
4973 		 * needs to be released from the context of kmem_move_buffers().
4974 		 * kmem deferred unmapping the buffers on these slabs in order
4975 		 * to guarantee that buffers passed to the move callback have
4976 		 * been touched only by kmem or by the client itself.
4977 		 */
4978 		while ((sp = list_remove_head(deadlist)) != NULL) {
4979 			if (sp->slab_flags & KMEM_SLAB_MOVE_PENDING) {
4980 				list_insert_tail(deadlist, sp);
4981 				break;
4982 			}
4983 			cp->cache_defrag->kmd_deadcount--;
4984 			cp->cache_slab_destroy++;
4985 			mutex_exit(&cp->cache_lock);
4986 			kmem_slab_destroy(cp, sp);
4987 			mutex_enter(&cp->cache_lock);
4988 		}
4989 	}
4990 	mutex_exit(&cp->cache_lock);
4991 	kmem_cache_free(kmem_move_cache, callback);
4992 }
4993 
4994 /*
4995  * Move buffers from least used slabs first by scanning backwards from the end
4996  * of the partial slab list. Scan at most max_scan candidate slabs and move
4997  * buffers from at most max_slabs slabs (0 for all partial slabs in both cases).
4998  * If desperate to reclaim memory, move buffers from any partial slab, otherwise
4999  * skip slabs with a ratio of allocated buffers at or above the current
5000  * threshold. Return the number of unskipped slabs (at most max_slabs, -1 if the
5001  * scan is aborted) so that the caller can adjust the reclaimability threshold
5002  * depending on how many reclaimable slabs it finds.
5003  *
5004  * kmem_move_buffers() drops and reacquires cache_lock every time it issues a
5005  * move request, since it is not valid for kmem_move_begin() to call
5006  * kmem_cache_alloc() or taskq_dispatch() with cache_lock held.
5007  */
5008 static int
kmem_move_buffers(kmem_cache_t * cp,size_t max_scan,size_t max_slabs,int flags)5009 kmem_move_buffers(kmem_cache_t *cp, size_t max_scan, size_t max_slabs,
5010     int flags)
5011 {
5012 	kmem_slab_t *sp;
5013 	void *buf;
5014 	int i, j; /* slab index, buffer index */
5015 	int s; /* reclaimable slabs */
5016 	int b; /* allocated (movable) buffers on reclaimable slab */
5017 	boolean_t success;
5018 	int refcnt;
5019 	int nomove;
5020 
5021 	ASSERT(taskq_member(kmem_taskq, curthread));
5022 	ASSERT(MUTEX_HELD(&cp->cache_lock));
5023 	ASSERT(kmem_move_cache != NULL);
5024 	ASSERT(cp->cache_move != NULL && cp->cache_defrag != NULL);
5025 	ASSERT((flags & KMM_DEBUG) ? !avl_is_empty(&cp->cache_partial_slabs) :
5026 	    avl_numnodes(&cp->cache_partial_slabs) > 1);
5027 
5028 	if (kmem_move_blocked) {
5029 		return (0);
5030 	}
5031 
5032 	if (kmem_move_fulltilt) {
5033 		flags |= KMM_DESPERATE;
5034 	}
5035 
5036 	if (max_scan == 0 || (flags & KMM_DESPERATE)) {
5037 		/*
5038 		 * Scan as many slabs as needed to find the desired number of
5039 		 * candidate slabs.
5040 		 */
5041 		max_scan = (size_t)-1;
5042 	}
5043 
5044 	if (max_slabs == 0 || (flags & KMM_DESPERATE)) {
5045 		/* Find as many candidate slabs as possible. */
5046 		max_slabs = (size_t)-1;
5047 	}
5048 
5049 	sp = avl_last(&cp->cache_partial_slabs);
5050 	ASSERT(KMEM_SLAB_IS_PARTIAL(sp));
5051 	for (i = 0, s = 0; (i < max_scan) && (s < max_slabs) && (sp != NULL) &&
5052 	    ((sp != avl_first(&cp->cache_partial_slabs)) ||
5053 	    (flags & KMM_DEBUG));
5054 	    sp = AVL_PREV(&cp->cache_partial_slabs, sp), i++) {
5055 
5056 		if (!kmem_slab_is_reclaimable(cp, sp, flags)) {
5057 			continue;
5058 		}
5059 		s++;
5060 
5061 		/* Look for allocated buffers to move. */
5062 		for (j = 0, b = 0, buf = sp->slab_base;
5063 		    (j < sp->slab_chunks) && (b < sp->slab_refcnt);
5064 		    buf = (((char *)buf) + cp->cache_chunksize), j++) {
5065 
5066 			if (kmem_slab_allocated(cp, sp, buf) == NULL) {
5067 				continue;
5068 			}
5069 
5070 			b++;
5071 
5072 			/*
5073 			 * Prevent the slab from being destroyed while we drop
5074 			 * cache_lock and while the pending move is not yet
5075 			 * registered. Flag the pending move while
5076 			 * kmd_moves_pending may still be empty, since we can't
5077 			 * yet rely on a non-zero pending move count to prevent
5078 			 * the slab from being destroyed.
5079 			 */
5080 			ASSERT(!(sp->slab_flags & KMEM_SLAB_MOVE_PENDING));
5081 			sp->slab_flags |= KMEM_SLAB_MOVE_PENDING;
5082 			/*
5083 			 * Recheck refcnt and nomove after reacquiring the lock,
5084 			 * since these control the order of partial slabs, and
5085 			 * we want to know if we can pick up the scan where we
5086 			 * left off.
5087 			 */
5088 			refcnt = sp->slab_refcnt;
5089 			nomove = (sp->slab_flags & KMEM_SLAB_NOMOVE);
5090 			mutex_exit(&cp->cache_lock);
5091 
5092 			success = kmem_move_begin(cp, sp, buf, flags);
5093 
5094 			/*
5095 			 * Now, before the lock is reacquired, kmem could
5096 			 * process all pending move requests and purge the
5097 			 * deadlist, so that upon reacquiring the lock, sp has
5098 			 * been remapped. Or, the client may free all the
5099 			 * objects on the slab while the pending moves are still
5100 			 * on the taskq. Therefore, the KMEM_SLAB_MOVE_PENDING
5101 			 * flag causes the slab to be put at the end of the
5102 			 * deadlist and prevents it from being destroyed, since
5103 			 * we plan to destroy it here after reacquiring the
5104 			 * lock.
5105 			 */
5106 			mutex_enter(&cp->cache_lock);
5107 			ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
5108 			sp->slab_flags &= ~KMEM_SLAB_MOVE_PENDING;
5109 
5110 			if (sp->slab_refcnt == 0) {
5111 				list_t *deadlist =
5112 				    &cp->cache_defrag->kmd_deadlist;
5113 				list_remove(deadlist, sp);
5114 
5115 				if (!avl_is_empty(
5116 				    &cp->cache_defrag->kmd_moves_pending)) {
5117 					/*
5118 					 * A pending move makes it unsafe to
5119 					 * destroy the slab, because even though
5120 					 * the move is no longer needed, the
5121 					 * context where that is determined
5122 					 * requires the slab to exist.
5123 					 * Fortunately, a pending move also
5124 					 * means we don't need to destroy the
5125 					 * slab here, since it will get
5126 					 * destroyed along with any other slabs
5127 					 * on the deadlist after the last
5128 					 * pending move completes.
5129 					 */
5130 					list_insert_head(deadlist, sp);
5131 					return (-1);
5132 				}
5133 
5134 				/*
5135 				 * Destroy the slab now if it was completely
5136 				 * freed while we dropped cache_lock and there
5137 				 * are no pending moves. Since slab_refcnt
5138 				 * cannot change once it reaches zero, no new
5139 				 * pending moves from that slab are possible.
5140 				 */
5141 				cp->cache_defrag->kmd_deadcount--;
5142 				cp->cache_slab_destroy++;
5143 				mutex_exit(&cp->cache_lock);
5144 				kmem_slab_destroy(cp, sp);
5145 				mutex_enter(&cp->cache_lock);
5146 				/*
5147 				 * Since we can't pick up the scan where we left
5148 				 * off, abort the scan and say nothing about the
5149 				 * number of reclaimable slabs.
5150 				 */
5151 				return (-1);
5152 			}
5153 
5154 			if (!success) {
5155 				/*
5156 				 * Abort the scan if there is not enough memory
5157 				 * for the request and say nothing about the
5158 				 * number of reclaimable slabs.
5159 				 */
5160 				return (-1);
5161 			}
5162 
5163 			/*
5164 			 * The slab's position changed while the lock was
5165 			 * dropped, so we don't know where we are in the
5166 			 * sequence any more.
5167 			 */
5168 			if (sp->slab_refcnt != refcnt) {
5169 				/*
5170 				 * If this is a KMM_DEBUG move, the slab_refcnt
5171 				 * may have changed because we allocated a
5172 				 * destination buffer on the same slab. In that
5173 				 * case, we're not interested in counting it.
5174 				 */
5175 				return (-1);
5176 			}
5177 			if ((sp->slab_flags & KMEM_SLAB_NOMOVE) != nomove)
5178 				return (-1);
5179 
5180 			/*
5181 			 * Generating a move request allocates a destination
5182 			 * buffer from the slab layer, bumping the first partial
5183 			 * slab if it is completely allocated. If the current
5184 			 * slab becomes the first partial slab as a result, we
5185 			 * can't continue to scan backwards.
5186 			 *
5187 			 * If this is a KMM_DEBUG move and we allocated the
5188 			 * destination buffer from the last partial slab, then
5189 			 * the buffer we're moving is on the same slab and our
5190 			 * slab_refcnt has changed, causing us to return before
5191 			 * reaching here if there are no partial slabs left.
5192 			 */
5193 			ASSERT(!avl_is_empty(&cp->cache_partial_slabs));
5194 			if (sp == avl_first(&cp->cache_partial_slabs)) {
5195 				/*
5196 				 * We're not interested in a second KMM_DEBUG
5197 				 * move.
5198 				 */
5199 				goto end_scan;
5200 			}
5201 		}
5202 	}
5203 end_scan:
5204 
5205 	return (s);
5206 }
5207 
5208 typedef struct kmem_move_notify_args {
5209 	kmem_cache_t *kmna_cache;
5210 	void *kmna_buf;
5211 } kmem_move_notify_args_t;
5212 
5213 static void
kmem_cache_move_notify_task(void * arg)5214 kmem_cache_move_notify_task(void *arg)
5215 {
5216 	kmem_move_notify_args_t *args = arg;
5217 	kmem_cache_t *cp = args->kmna_cache;
5218 	void *buf = args->kmna_buf;
5219 	kmem_slab_t *sp;
5220 
5221 	ASSERT(taskq_member(kmem_taskq, curthread));
5222 	ASSERT(list_link_active(&cp->cache_link));
5223 
5224 	kmem_free(args, sizeof (kmem_move_notify_args_t));
5225 	mutex_enter(&cp->cache_lock);
5226 	sp = kmem_slab_allocated(cp, NULL, buf);
5227 
5228 	/* Ignore the notification if the buffer is no longer allocated. */
5229 	if (sp == NULL) {
5230 		mutex_exit(&cp->cache_lock);
5231 		return;
5232 	}
5233 
5234 	/* Ignore the notification if there's no reason to move the buffer. */
5235 	if (avl_numnodes(&cp->cache_partial_slabs) > 1) {
5236 		/*
5237 		 * So far the notification is not ignored. Ignore the
5238 		 * notification if the slab is not marked by an earlier refusal
5239 		 * to move a buffer.
5240 		 */
5241 		if (!(sp->slab_flags & KMEM_SLAB_NOMOVE) &&
5242 		    (sp->slab_later_count == 0)) {
5243 			mutex_exit(&cp->cache_lock);
5244 			return;
5245 		}
5246 
5247 		kmem_slab_move_yes(cp, sp, buf);
5248 		ASSERT(!(sp->slab_flags & KMEM_SLAB_MOVE_PENDING));
5249 		sp->slab_flags |= KMEM_SLAB_MOVE_PENDING;
5250 		mutex_exit(&cp->cache_lock);
5251 		/* see kmem_move_buffers() about dropping the lock */
5252 		(void) kmem_move_begin(cp, sp, buf, KMM_NOTIFY);
5253 		mutex_enter(&cp->cache_lock);
5254 		ASSERT(sp->slab_flags & KMEM_SLAB_MOVE_PENDING);
5255 		sp->slab_flags &= ~KMEM_SLAB_MOVE_PENDING;
5256 		if (sp->slab_refcnt == 0) {
5257 			list_t *deadlist = &cp->cache_defrag->kmd_deadlist;
5258 			list_remove(deadlist, sp);
5259 
5260 			if (!avl_is_empty(
5261 			    &cp->cache_defrag->kmd_moves_pending)) {
5262 				list_insert_head(deadlist, sp);
5263 				mutex_exit(&cp->cache_lock);
5264 				return;
5265 			}
5266 
5267 			cp->cache_defrag->kmd_deadcount--;
5268 			cp->cache_slab_destroy++;
5269 			mutex_exit(&cp->cache_lock);
5270 			kmem_slab_destroy(cp, sp);
5271 			return;
5272 		}
5273 	} else {
5274 		kmem_slab_move_yes(cp, sp, buf);
5275 	}
5276 	mutex_exit(&cp->cache_lock);
5277 }
5278 
5279 void
kmem_cache_move_notify(kmem_cache_t * cp,void * buf)5280 kmem_cache_move_notify(kmem_cache_t *cp, void *buf)
5281 {
5282 	kmem_move_notify_args_t *args;
5283 
5284 	args = kmem_alloc(sizeof (kmem_move_notify_args_t), KM_NOSLEEP);
5285 	if (args != NULL) {
5286 		args->kmna_cache = cp;
5287 		args->kmna_buf = buf;
5288 		if (taskq_dispatch(kmem_taskq,
5289 		    (task_func_t *)kmem_cache_move_notify_task, args,
5290 		    TQ_NOSLEEP) == TASKQID_INVALID)
5291 			kmem_free(args, sizeof (kmem_move_notify_args_t));
5292 	}
5293 }
5294 
5295 static void
kmem_cache_defrag(kmem_cache_t * cp)5296 kmem_cache_defrag(kmem_cache_t *cp)
5297 {
5298 	size_t n;
5299 
5300 	ASSERT(cp->cache_defrag != NULL);
5301 
5302 	mutex_enter(&cp->cache_lock);
5303 	n = avl_numnodes(&cp->cache_partial_slabs);
5304 	if (n > 1) {
5305 		/* kmem_move_buffers() drops and reacquires cache_lock */
5306 		cp->cache_defrag->kmd_defrags++;
5307 		(void) kmem_move_buffers(cp, n, 0, KMM_DESPERATE);
5308 	}
5309 	mutex_exit(&cp->cache_lock);
5310 }
5311 
5312 /* Is this cache above the fragmentation threshold? */
5313 static boolean_t
kmem_cache_frag_threshold(kmem_cache_t * cp,uint64_t nfree)5314 kmem_cache_frag_threshold(kmem_cache_t *cp, uint64_t nfree)
5315 {
5316 	/*
5317 	 *	nfree		kmem_frag_numer
5318 	 * ------------------ > ---------------
5319 	 * cp->cache_buftotal	kmem_frag_denom
5320 	 */
5321 	return ((nfree * kmem_frag_denom) >
5322 	    (cp->cache_buftotal * kmem_frag_numer));
5323 }
5324 
5325 static boolean_t
kmem_cache_is_fragmented(kmem_cache_t * cp,boolean_t * doreap)5326 kmem_cache_is_fragmented(kmem_cache_t *cp, boolean_t *doreap)
5327 {
5328 	boolean_t fragmented;
5329 	uint64_t nfree;
5330 
5331 	ASSERT(MUTEX_HELD(&cp->cache_lock));
5332 	*doreap = B_FALSE;
5333 
5334 	if (kmem_move_fulltilt) {
5335 		if (avl_numnodes(&cp->cache_partial_slabs) > 1) {
5336 			return (B_TRUE);
5337 		}
5338 	} else {
5339 		if ((cp->cache_complete_slab_count + avl_numnodes(
5340 		    &cp->cache_partial_slabs)) < kmem_frag_minslabs) {
5341 			return (B_FALSE);
5342 		}
5343 	}
5344 
5345 	nfree = cp->cache_bufslab;
5346 	fragmented = ((avl_numnodes(&cp->cache_partial_slabs) > 1) &&
5347 	    kmem_cache_frag_threshold(cp, nfree));
5348 
5349 	/*
5350 	 * Free buffers in the magazine layer appear allocated from the point of
5351 	 * view of the slab layer. We want to know if the slab layer would
5352 	 * appear fragmented if we included free buffers from magazines that
5353 	 * have fallen out of the working set.
5354 	 */
5355 	if (!fragmented) {
5356 		long reap;
5357 
5358 		mutex_enter(&cp->cache_depot_lock);
5359 		reap = MIN(cp->cache_full.ml_reaplimit, cp->cache_full.ml_min);
5360 		reap = MIN(reap, cp->cache_full.ml_total);
5361 		mutex_exit(&cp->cache_depot_lock);
5362 
5363 		nfree += ((uint64_t)reap * cp->cache_magtype->mt_magsize);
5364 		if (kmem_cache_frag_threshold(cp, nfree)) {
5365 			*doreap = B_TRUE;
5366 		}
5367 	}
5368 
5369 	return (fragmented);
5370 }
5371 
5372 /* Called periodically from kmem_taskq */
5373 static void
kmem_cache_scan(kmem_cache_t * cp)5374 kmem_cache_scan(kmem_cache_t *cp)
5375 {
5376 	boolean_t reap = B_FALSE;
5377 	kmem_defrag_t *kmd;
5378 
5379 	ASSERT(taskq_member(kmem_taskq, curthread));
5380 
5381 	mutex_enter(&cp->cache_lock);
5382 
5383 	kmd = cp->cache_defrag;
5384 	if (kmd->kmd_consolidate > 0) {
5385 		kmd->kmd_consolidate--;
5386 		mutex_exit(&cp->cache_lock);
5387 		kmem_cache_reap(cp);
5388 		return;
5389 	}
5390 
5391 	if (kmem_cache_is_fragmented(cp, &reap)) {
5392 		int slabs_found;
5393 
5394 		/*
5395 		 * Consolidate reclaimable slabs from the end of the partial
5396 		 * slab list (scan at most kmem_reclaim_scan_range slabs to find
5397 		 * reclaimable slabs). Keep track of how many candidate slabs we
5398 		 * looked for and how many we actually found so we can adjust
5399 		 * the definition of a candidate slab if we're having trouble
5400 		 * finding them.
5401 		 *
5402 		 * kmem_move_buffers() drops and reacquires cache_lock.
5403 		 */
5404 		kmd->kmd_scans++;
5405 		slabs_found = kmem_move_buffers(cp, kmem_reclaim_scan_range,
5406 		    kmem_reclaim_max_slabs, 0);
5407 		if (slabs_found >= 0) {
5408 			kmd->kmd_slabs_sought += kmem_reclaim_max_slabs;
5409 			kmd->kmd_slabs_found += slabs_found;
5410 		}
5411 
5412 		if (++kmd->kmd_tries >= kmem_reclaim_scan_range) {
5413 			kmd->kmd_tries = 0;
5414 
5415 			/*
5416 			 * If we had difficulty finding candidate slabs in
5417 			 * previous scans, adjust the threshold so that
5418 			 * candidates are easier to find.
5419 			 */
5420 			if (kmd->kmd_slabs_found == kmd->kmd_slabs_sought) {
5421 				kmem_adjust_reclaim_threshold(kmd, -1);
5422 			} else if ((kmd->kmd_slabs_found * 2) <
5423 			    kmd->kmd_slabs_sought) {
5424 				kmem_adjust_reclaim_threshold(kmd, 1);
5425 			}
5426 			kmd->kmd_slabs_sought = 0;
5427 			kmd->kmd_slabs_found = 0;
5428 		}
5429 	} else {
5430 		kmem_reset_reclaim_threshold(cp->cache_defrag);
5431 #ifdef	DEBUG
5432 		if (!avl_is_empty(&cp->cache_partial_slabs)) {
5433 			/*
5434 			 * In a debug kernel we want the consolidator to
5435 			 * run occasionally even when there is plenty of
5436 			 * memory.
5437 			 */
5438 			uint16_t debug_rand;
5439 
5440 			(void) random_get_bytes((uint8_t *)&debug_rand, 2);
5441 			if (!kmem_move_noreap &&
5442 			    ((debug_rand % kmem_mtb_reap) == 0)) {
5443 				mutex_exit(&cp->cache_lock);
5444 				kmem_cache_reap(cp);
5445 				return;
5446 			} else if ((debug_rand % kmem_mtb_move) == 0) {
5447 				kmd->kmd_scans++;
5448 				(void) kmem_move_buffers(cp,
5449 				    kmem_reclaim_scan_range, 1, KMM_DEBUG);
5450 			}
5451 		}
5452 #endif	/* DEBUG */
5453 	}
5454 
5455 	mutex_exit(&cp->cache_lock);
5456 
5457 	if (reap)
5458 		kmem_depot_ws_reap(cp);
5459 }
5460