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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/mempool.c
4 *
5 * memory buffer pool support. Such pools are mostly used
6 * for guaranteed, deadlock-free memory allocations during
7 * extreme VM load.
8 *
9 * started by Ingo Molnar, Copyright (C) 2001
10 * debugging by David Rientjes, Copyright (C) 2015
11 */
12
13#include <linux/mm.h>
14#include <linux/slab.h>
15#include <linux/highmem.h>
16#include <linux/kasan.h>
17#include <linux/kmemleak.h>
18#include <linux/export.h>
19#include <linux/mempool.h>
20#include <linux/blkdev.h>
21#include <linux/writeback.h>
22#include "slab.h"
23
24#if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
25static void poison_error(mempool_t *pool, void *element, size_t size,
26 size_t byte)
27{
28 const int nr = pool->curr_nr;
29 const int start = max_t(int, byte - (BITS_PER_LONG / 8), 0);
30 const int end = min_t(int, byte + (BITS_PER_LONG / 8), size);
31 int i;
32
33 pr_err("BUG: mempool element poison mismatch\n");
34 pr_err("Mempool %p size %zu\n", pool, size);
35 pr_err(" nr=%d @ %p: %s0x", nr, element, start > 0 ? "... " : "");
36 for (i = start; i < end; i++)
37 pr_cont("%x ", *(u8 *)(element + i));
38 pr_cont("%s\n", end < size ? "..." : "");
39 dump_stack();
40}
41
42static void __check_element(mempool_t *pool, void *element, size_t size)
43{
44 u8 *obj = element;
45 size_t i;
46
47 for (i = 0; i < size; i++) {
48 u8 exp = (i < size - 1) ? POISON_FREE : POISON_END;
49
50 if (obj[i] != exp) {
51 poison_error(pool, element, size, i);
52 return;
53 }
54 }
55 memset(obj, POISON_INUSE, size);
56}
57
58static void check_element(mempool_t *pool, void *element)
59{
60 /* Mempools backed by slab allocator */
61 if (pool->free == mempool_free_slab || pool->free == mempool_kfree)
62 __check_element(pool, element, ksize(element));
63
64 /* Mempools backed by page allocator */
65 if (pool->free == mempool_free_pages) {
66 int order = (int)(long)pool->pool_data;
67 void *addr = kmap_atomic((struct page *)element);
68
69 __check_element(pool, addr, 1UL << (PAGE_SHIFT + order));
70 kunmap_atomic(addr);
71 }
72}
73
74static void __poison_element(void *element, size_t size)
75{
76 u8 *obj = element;
77
78 memset(obj, POISON_FREE, size - 1);
79 obj[size - 1] = POISON_END;
80}
81
82static void poison_element(mempool_t *pool, void *element)
83{
84 /* Mempools backed by slab allocator */
85 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
86 __poison_element(element, ksize(element));
87
88 /* Mempools backed by page allocator */
89 if (pool->alloc == mempool_alloc_pages) {
90 int order = (int)(long)pool->pool_data;
91 void *addr = kmap_atomic((struct page *)element);
92
93 __poison_element(addr, 1UL << (PAGE_SHIFT + order));
94 kunmap_atomic(addr);
95 }
96}
97#else /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
98static inline void check_element(mempool_t *pool, void *element)
99{
100}
101static inline void poison_element(mempool_t *pool, void *element)
102{
103}
104#endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
105
106static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
107{
108 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
109 kasan_poison_kfree(element, _RET_IP_);
110 if (pool->alloc == mempool_alloc_pages)
111 kasan_free_pages(element, (unsigned long)pool->pool_data);
112}
113
114static void kasan_unpoison_element(mempool_t *pool, void *element)
115{
116 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
117 kasan_unpoison_slab(element);
118 if (pool->alloc == mempool_alloc_pages)
119 kasan_alloc_pages(element, (unsigned long)pool->pool_data);
120}
121
122static __always_inline void add_element(mempool_t *pool, void *element)
123{
124 BUG_ON(pool->curr_nr >= pool->min_nr);
125 poison_element(pool, element);
126 kasan_poison_element(pool, element);
127 pool->elements[pool->curr_nr++] = element;
128}
129
130static void *remove_element(mempool_t *pool)
131{
132 void *element = pool->elements[--pool->curr_nr];
133
134 BUG_ON(pool->curr_nr < 0);
135 kasan_unpoison_element(pool, element);
136 check_element(pool, element);
137 return element;
138}
139
140/**
141 * mempool_exit - exit a mempool initialized with mempool_init()
142 * @pool: pointer to the memory pool which was initialized with
143 * mempool_init().
144 *
145 * Free all reserved elements in @pool and @pool itself. This function
146 * only sleeps if the free_fn() function sleeps.
147 *
148 * May be called on a zeroed but uninitialized mempool (i.e. allocated with
149 * kzalloc()).
150 */
151void mempool_exit(mempool_t *pool)
152{
153 while (pool->curr_nr) {
154 void *element = remove_element(pool);
155 pool->free(element, pool->pool_data);
156 }
157 kfree(pool->elements);
158 pool->elements = NULL;
159}
160EXPORT_SYMBOL(mempool_exit);
161
162/**
163 * mempool_destroy - deallocate a memory pool
164 * @pool: pointer to the memory pool which was allocated via
165 * mempool_create().
166 *
167 * Free all reserved elements in @pool and @pool itself. This function
168 * only sleeps if the free_fn() function sleeps.
169 */
170void mempool_destroy(mempool_t *pool)
171{
172 if (unlikely(!pool))
173 return;
174
175 mempool_exit(pool);
176 kfree(pool);
177}
178EXPORT_SYMBOL(mempool_destroy);
179
180int mempool_init_node(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
181 mempool_free_t *free_fn, void *pool_data,
182 gfp_t gfp_mask, int node_id)
183{
184 spin_lock_init(&pool->lock);
185 pool->min_nr = min_nr;
186 pool->pool_data = pool_data;
187 pool->alloc = alloc_fn;
188 pool->free = free_fn;
189 init_waitqueue_head(&pool->wait);
190
191 pool->elements = kmalloc_array_node(min_nr, sizeof(void *),
192 gfp_mask, node_id);
193 if (!pool->elements)
194 return -ENOMEM;
195
196 /*
197 * First pre-allocate the guaranteed number of buffers.
198 */
199 while (pool->curr_nr < pool->min_nr) {
200 void *element;
201
202 element = pool->alloc(gfp_mask, pool->pool_data);
203 if (unlikely(!element)) {
204 mempool_exit(pool);
205 return -ENOMEM;
206 }
207 add_element(pool, element);
208 }
209
210 return 0;
211}
212EXPORT_SYMBOL(mempool_init_node);
213
214/**
215 * mempool_init - initialize a memory pool
216 * @pool: pointer to the memory pool that should be initialized
217 * @min_nr: the minimum number of elements guaranteed to be
218 * allocated for this pool.
219 * @alloc_fn: user-defined element-allocation function.
220 * @free_fn: user-defined element-freeing function.
221 * @pool_data: optional private data available to the user-defined functions.
222 *
223 * Like mempool_create(), but initializes the pool in (i.e. embedded in another
224 * structure).
225 *
226 * Return: %0 on success, negative error code otherwise.
227 */
228int mempool_init(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
229 mempool_free_t *free_fn, void *pool_data)
230{
231 return mempool_init_node(pool, min_nr, alloc_fn, free_fn,
232 pool_data, GFP_KERNEL, NUMA_NO_NODE);
233
234}
235EXPORT_SYMBOL(mempool_init);
236
237/**
238 * mempool_create - create a memory pool
239 * @min_nr: the minimum number of elements guaranteed to be
240 * allocated for this pool.
241 * @alloc_fn: user-defined element-allocation function.
242 * @free_fn: user-defined element-freeing function.
243 * @pool_data: optional private data available to the user-defined functions.
244 *
245 * this function creates and allocates a guaranteed size, preallocated
246 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
247 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
248 * functions might sleep - as long as the mempool_alloc() function is not called
249 * from IRQ contexts.
250 *
251 * Return: pointer to the created memory pool object or %NULL on error.
252 */
253mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
254 mempool_free_t *free_fn, void *pool_data)
255{
256 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,
257 GFP_KERNEL, NUMA_NO_NODE);
258}
259EXPORT_SYMBOL(mempool_create);
260
261mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
262 mempool_free_t *free_fn, void *pool_data,
263 gfp_t gfp_mask, int node_id)
264{
265 mempool_t *pool;
266
267 pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
268 if (!pool)
269 return NULL;
270
271 if (mempool_init_node(pool, min_nr, alloc_fn, free_fn, pool_data,
272 gfp_mask, node_id)) {
273 kfree(pool);
274 return NULL;
275 }
276
277 return pool;
278}
279EXPORT_SYMBOL(mempool_create_node);
280
281/**
282 * mempool_resize - resize an existing memory pool
283 * @pool: pointer to the memory pool which was allocated via
284 * mempool_create().
285 * @new_min_nr: the new minimum number of elements guaranteed to be
286 * allocated for this pool.
287 *
288 * This function shrinks/grows the pool. In the case of growing,
289 * it cannot be guaranteed that the pool will be grown to the new
290 * size immediately, but new mempool_free() calls will refill it.
291 * This function may sleep.
292 *
293 * Note, the caller must guarantee that no mempool_destroy is called
294 * while this function is running. mempool_alloc() & mempool_free()
295 * might be called (eg. from IRQ contexts) while this function executes.
296 *
297 * Return: %0 on success, negative error code otherwise.
298 */
299int mempool_resize(mempool_t *pool, int new_min_nr)
300{
301 void *element;
302 void **new_elements;
303 unsigned long flags;
304
305 BUG_ON(new_min_nr <= 0);
306 might_sleep();
307
308 spin_lock_irqsave(&pool->lock, flags);
309 if (new_min_nr <= pool->min_nr) {
310 while (new_min_nr < pool->curr_nr) {
311 element = remove_element(pool);
312 spin_unlock_irqrestore(&pool->lock, flags);
313 pool->free(element, pool->pool_data);
314 spin_lock_irqsave(&pool->lock, flags);
315 }
316 pool->min_nr = new_min_nr;
317 goto out_unlock;
318 }
319 spin_unlock_irqrestore(&pool->lock, flags);
320
321 /* Grow the pool */
322 new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements),
323 GFP_KERNEL);
324 if (!new_elements)
325 return -ENOMEM;
326
327 spin_lock_irqsave(&pool->lock, flags);
328 if (unlikely(new_min_nr <= pool->min_nr)) {
329 /* Raced, other resize will do our work */
330 spin_unlock_irqrestore(&pool->lock, flags);
331 kfree(new_elements);
332 goto out;
333 }
334 memcpy(new_elements, pool->elements,
335 pool->curr_nr * sizeof(*new_elements));
336 kfree(pool->elements);
337 pool->elements = new_elements;
338 pool->min_nr = new_min_nr;
339
340 while (pool->curr_nr < pool->min_nr) {
341 spin_unlock_irqrestore(&pool->lock, flags);
342 element = pool->alloc(GFP_KERNEL, pool->pool_data);
343 if (!element)
344 goto out;
345 spin_lock_irqsave(&pool->lock, flags);
346 if (pool->curr_nr < pool->min_nr) {
347 add_element(pool, element);
348 } else {
349 spin_unlock_irqrestore(&pool->lock, flags);
350 pool->free(element, pool->pool_data); /* Raced */
351 goto out;
352 }
353 }
354out_unlock:
355 spin_unlock_irqrestore(&pool->lock, flags);
356out:
357 return 0;
358}
359EXPORT_SYMBOL(mempool_resize);
360
361/**
362 * mempool_alloc - allocate an element from a specific memory pool
363 * @pool: pointer to the memory pool which was allocated via
364 * mempool_create().
365 * @gfp_mask: the usual allocation bitmask.
366 *
367 * this function only sleeps if the alloc_fn() function sleeps or
368 * returns NULL. Note that due to preallocation, this function
369 * *never* fails when called from process contexts. (it might
370 * fail if called from an IRQ context.)
371 * Note: using __GFP_ZERO is not supported.
372 *
373 * Return: pointer to the allocated element or %NULL on error.
374 */
375void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
376{
377 void *element;
378 unsigned long flags;
379 wait_queue_entry_t wait;
380 gfp_t gfp_temp;
381
382 VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
383 might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
384
385 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
386 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
387 gfp_mask |= __GFP_NOWARN; /* failures are OK */
388
389 gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
390
391repeat_alloc:
392
393 element = pool->alloc(gfp_temp, pool->pool_data);
394 if (likely(element != NULL))
395 return element;
396
397 spin_lock_irqsave(&pool->lock, flags);
398 if (likely(pool->curr_nr)) {
399 element = remove_element(pool);
400 spin_unlock_irqrestore(&pool->lock, flags);
401 /* paired with rmb in mempool_free(), read comment there */
402 smp_wmb();
403 /*
404 * Update the allocation stack trace as this is more useful
405 * for debugging.
406 */
407 kmemleak_update_trace(element);
408 return element;
409 }
410
411 /*
412 * We use gfp mask w/o direct reclaim or IO for the first round. If
413 * alloc failed with that and @pool was empty, retry immediately.
414 */
415 if (gfp_temp != gfp_mask) {
416 spin_unlock_irqrestore(&pool->lock, flags);
417 gfp_temp = gfp_mask;
418 goto repeat_alloc;
419 }
420
421 /* We must not sleep if !__GFP_DIRECT_RECLAIM */
422 if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
423 spin_unlock_irqrestore(&pool->lock, flags);
424 return NULL;
425 }
426
427 /* Let's wait for someone else to return an element to @pool */
428 init_wait(&wait);
429 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
430
431 spin_unlock_irqrestore(&pool->lock, flags);
432
433 /*
434 * FIXME: this should be io_schedule(). The timeout is there as a
435 * workaround for some DM problems in 2.6.18.
436 */
437 io_schedule_timeout(5*HZ);
438
439 finish_wait(&pool->wait, &wait);
440 goto repeat_alloc;
441}
442EXPORT_SYMBOL(mempool_alloc);
443
444/**
445 * mempool_free - return an element to the pool.
446 * @element: pool element pointer.
447 * @pool: pointer to the memory pool which was allocated via
448 * mempool_create().
449 *
450 * this function only sleeps if the free_fn() function sleeps.
451 */
452void mempool_free(void *element, mempool_t *pool)
453{
454 unsigned long flags;
455
456 if (unlikely(element == NULL))
457 return;
458
459 /*
460 * Paired with the wmb in mempool_alloc(). The preceding read is
461 * for @element and the following @pool->curr_nr. This ensures
462 * that the visible value of @pool->curr_nr is from after the
463 * allocation of @element. This is necessary for fringe cases
464 * where @element was passed to this task without going through
465 * barriers.
466 *
467 * For example, assume @p is %NULL at the beginning and one task
468 * performs "p = mempool_alloc(...);" while another task is doing
469 * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
470 * may end up using curr_nr value which is from before allocation
471 * of @p without the following rmb.
472 */
473 smp_rmb();
474
475 /*
476 * For correctness, we need a test which is guaranteed to trigger
477 * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
478 * without locking achieves that and refilling as soon as possible
479 * is desirable.
480 *
481 * Because curr_nr visible here is always a value after the
482 * allocation of @element, any task which decremented curr_nr below
483 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
484 * incremented to min_nr afterwards. If curr_nr gets incremented
485 * to min_nr after the allocation of @element, the elements
486 * allocated after that are subject to the same guarantee.
487 *
488 * Waiters happen iff curr_nr is 0 and the above guarantee also
489 * ensures that there will be frees which return elements to the
490 * pool waking up the waiters.
491 */
492 if (unlikely(pool->curr_nr < pool->min_nr)) {
493 spin_lock_irqsave(&pool->lock, flags);
494 if (likely(pool->curr_nr < pool->min_nr)) {
495 add_element(pool, element);
496 spin_unlock_irqrestore(&pool->lock, flags);
497 wake_up(&pool->wait);
498 return;
499 }
500 spin_unlock_irqrestore(&pool->lock, flags);
501 }
502 pool->free(element, pool->pool_data);
503}
504EXPORT_SYMBOL(mempool_free);
505
506/*
507 * A commonly used alloc and free fn.
508 */
509void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
510{
511 struct kmem_cache *mem = pool_data;
512 VM_BUG_ON(mem->ctor);
513 return kmem_cache_alloc(mem, gfp_mask);
514}
515EXPORT_SYMBOL(mempool_alloc_slab);
516
517void mempool_free_slab(void *element, void *pool_data)
518{
519 struct kmem_cache *mem = pool_data;
520 kmem_cache_free(mem, element);
521}
522EXPORT_SYMBOL(mempool_free_slab);
523
524/*
525 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
526 * specified by pool_data
527 */
528void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
529{
530 size_t size = (size_t)pool_data;
531 return kmalloc(size, gfp_mask);
532}
533EXPORT_SYMBOL(mempool_kmalloc);
534
535void mempool_kfree(void *element, void *pool_data)
536{
537 kfree(element);
538}
539EXPORT_SYMBOL(mempool_kfree);
540
541/*
542 * A simple mempool-backed page allocator that allocates pages
543 * of the order specified by pool_data.
544 */
545void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
546{
547 int order = (int)(long)pool_data;
548 return alloc_pages(gfp_mask, order);
549}
550EXPORT_SYMBOL(mempool_alloc_pages);
551
552void mempool_free_pages(void *element, void *pool_data)
553{
554 int order = (int)(long)pool_data;
555 __free_pages(element, order);
556}
557EXPORT_SYMBOL(mempool_free_pages);
1// SPDX-License-Identifier: GPL-2.0
2/*
3 * linux/mm/mempool.c
4 *
5 * memory buffer pool support. Such pools are mostly used
6 * for guaranteed, deadlock-free memory allocations during
7 * extreme VM load.
8 *
9 * started by Ingo Molnar, Copyright (C) 2001
10 * debugging by David Rientjes, Copyright (C) 2015
11 */
12
13#include <linux/mm.h>
14#include <linux/slab.h>
15#include <linux/highmem.h>
16#include <linux/kasan.h>
17#include <linux/kmemleak.h>
18#include <linux/export.h>
19#include <linux/mempool.h>
20#include <linux/writeback.h>
21#include "slab.h"
22
23#ifdef CONFIG_SLUB_DEBUG_ON
24static void poison_error(mempool_t *pool, void *element, size_t size,
25 size_t byte)
26{
27 const int nr = pool->curr_nr;
28 const int start = max_t(int, byte - (BITS_PER_LONG / 8), 0);
29 const int end = min_t(int, byte + (BITS_PER_LONG / 8), size);
30 int i;
31
32 pr_err("BUG: mempool element poison mismatch\n");
33 pr_err("Mempool %p size %zu\n", pool, size);
34 pr_err(" nr=%d @ %p: %s0x", nr, element, start > 0 ? "... " : "");
35 for (i = start; i < end; i++)
36 pr_cont("%x ", *(u8 *)(element + i));
37 pr_cont("%s\n", end < size ? "..." : "");
38 dump_stack();
39}
40
41static void __check_element(mempool_t *pool, void *element, size_t size)
42{
43 u8 *obj = element;
44 size_t i;
45
46 for (i = 0; i < size; i++) {
47 u8 exp = (i < size - 1) ? POISON_FREE : POISON_END;
48
49 if (obj[i] != exp) {
50 poison_error(pool, element, size, i);
51 return;
52 }
53 }
54 memset(obj, POISON_INUSE, size);
55}
56
57static void check_element(mempool_t *pool, void *element)
58{
59 /* Skip checking: KASAN might save its metadata in the element. */
60 if (kasan_enabled())
61 return;
62
63 /* Mempools backed by slab allocator */
64 if (pool->free == mempool_kfree) {
65 __check_element(pool, element, (size_t)pool->pool_data);
66 } else if (pool->free == mempool_free_slab) {
67 __check_element(pool, element, kmem_cache_size(pool->pool_data));
68 } else if (pool->free == mempool_free_pages) {
69 /* Mempools backed by page allocator */
70 int order = (int)(long)pool->pool_data;
71 void *addr = kmap_local_page((struct page *)element);
72
73 __check_element(pool, addr, 1UL << (PAGE_SHIFT + order));
74 kunmap_local(addr);
75 }
76}
77
78static void __poison_element(void *element, size_t size)
79{
80 u8 *obj = element;
81
82 memset(obj, POISON_FREE, size - 1);
83 obj[size - 1] = POISON_END;
84}
85
86static void poison_element(mempool_t *pool, void *element)
87{
88 /* Skip poisoning: KASAN might save its metadata in the element. */
89 if (kasan_enabled())
90 return;
91
92 /* Mempools backed by slab allocator */
93 if (pool->alloc == mempool_kmalloc) {
94 __poison_element(element, (size_t)pool->pool_data);
95 } else if (pool->alloc == mempool_alloc_slab) {
96 __poison_element(element, kmem_cache_size(pool->pool_data));
97 } else if (pool->alloc == mempool_alloc_pages) {
98 /* Mempools backed by page allocator */
99 int order = (int)(long)pool->pool_data;
100 void *addr = kmap_local_page((struct page *)element);
101
102 __poison_element(addr, 1UL << (PAGE_SHIFT + order));
103 kunmap_local(addr);
104 }
105}
106#else /* CONFIG_SLUB_DEBUG_ON */
107static inline void check_element(mempool_t *pool, void *element)
108{
109}
110static inline void poison_element(mempool_t *pool, void *element)
111{
112}
113#endif /* CONFIG_SLUB_DEBUG_ON */
114
115static __always_inline bool kasan_poison_element(mempool_t *pool, void *element)
116{
117 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
118 return kasan_mempool_poison_object(element);
119 else if (pool->alloc == mempool_alloc_pages)
120 return kasan_mempool_poison_pages(element,
121 (unsigned long)pool->pool_data);
122 return true;
123}
124
125static void kasan_unpoison_element(mempool_t *pool, void *element)
126{
127 if (pool->alloc == mempool_kmalloc)
128 kasan_mempool_unpoison_object(element, (size_t)pool->pool_data);
129 else if (pool->alloc == mempool_alloc_slab)
130 kasan_mempool_unpoison_object(element,
131 kmem_cache_size(pool->pool_data));
132 else if (pool->alloc == mempool_alloc_pages)
133 kasan_mempool_unpoison_pages(element,
134 (unsigned long)pool->pool_data);
135}
136
137static __always_inline void add_element(mempool_t *pool, void *element)
138{
139 BUG_ON(pool->curr_nr >= pool->min_nr);
140 poison_element(pool, element);
141 if (kasan_poison_element(pool, element))
142 pool->elements[pool->curr_nr++] = element;
143}
144
145static void *remove_element(mempool_t *pool)
146{
147 void *element = pool->elements[--pool->curr_nr];
148
149 BUG_ON(pool->curr_nr < 0);
150 kasan_unpoison_element(pool, element);
151 check_element(pool, element);
152 return element;
153}
154
155/**
156 * mempool_exit - exit a mempool initialized with mempool_init()
157 * @pool: pointer to the memory pool which was initialized with
158 * mempool_init().
159 *
160 * Free all reserved elements in @pool and @pool itself. This function
161 * only sleeps if the free_fn() function sleeps.
162 *
163 * May be called on a zeroed but uninitialized mempool (i.e. allocated with
164 * kzalloc()).
165 */
166void mempool_exit(mempool_t *pool)
167{
168 while (pool->curr_nr) {
169 void *element = remove_element(pool);
170 pool->free(element, pool->pool_data);
171 }
172 kfree(pool->elements);
173 pool->elements = NULL;
174}
175EXPORT_SYMBOL(mempool_exit);
176
177/**
178 * mempool_destroy - deallocate a memory pool
179 * @pool: pointer to the memory pool which was allocated via
180 * mempool_create().
181 *
182 * Free all reserved elements in @pool and @pool itself. This function
183 * only sleeps if the free_fn() function sleeps.
184 */
185void mempool_destroy(mempool_t *pool)
186{
187 if (unlikely(!pool))
188 return;
189
190 mempool_exit(pool);
191 kfree(pool);
192}
193EXPORT_SYMBOL(mempool_destroy);
194
195int mempool_init_node(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
196 mempool_free_t *free_fn, void *pool_data,
197 gfp_t gfp_mask, int node_id)
198{
199 spin_lock_init(&pool->lock);
200 pool->min_nr = min_nr;
201 pool->pool_data = pool_data;
202 pool->alloc = alloc_fn;
203 pool->free = free_fn;
204 init_waitqueue_head(&pool->wait);
205
206 pool->elements = kmalloc_array_node(min_nr, sizeof(void *),
207 gfp_mask, node_id);
208 if (!pool->elements)
209 return -ENOMEM;
210
211 /*
212 * First pre-allocate the guaranteed number of buffers.
213 */
214 while (pool->curr_nr < pool->min_nr) {
215 void *element;
216
217 element = pool->alloc(gfp_mask, pool->pool_data);
218 if (unlikely(!element)) {
219 mempool_exit(pool);
220 return -ENOMEM;
221 }
222 add_element(pool, element);
223 }
224
225 return 0;
226}
227EXPORT_SYMBOL(mempool_init_node);
228
229/**
230 * mempool_init - initialize a memory pool
231 * @pool: pointer to the memory pool that should be initialized
232 * @min_nr: the minimum number of elements guaranteed to be
233 * allocated for this pool.
234 * @alloc_fn: user-defined element-allocation function.
235 * @free_fn: user-defined element-freeing function.
236 * @pool_data: optional private data available to the user-defined functions.
237 *
238 * Like mempool_create(), but initializes the pool in (i.e. embedded in another
239 * structure).
240 *
241 * Return: %0 on success, negative error code otherwise.
242 */
243int mempool_init(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
244 mempool_free_t *free_fn, void *pool_data)
245{
246 return mempool_init_node(pool, min_nr, alloc_fn, free_fn,
247 pool_data, GFP_KERNEL, NUMA_NO_NODE);
248
249}
250EXPORT_SYMBOL(mempool_init);
251
252/**
253 * mempool_create - create a memory pool
254 * @min_nr: the minimum number of elements guaranteed to be
255 * allocated for this pool.
256 * @alloc_fn: user-defined element-allocation function.
257 * @free_fn: user-defined element-freeing function.
258 * @pool_data: optional private data available to the user-defined functions.
259 *
260 * this function creates and allocates a guaranteed size, preallocated
261 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
262 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
263 * functions might sleep - as long as the mempool_alloc() function is not called
264 * from IRQ contexts.
265 *
266 * Return: pointer to the created memory pool object or %NULL on error.
267 */
268mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
269 mempool_free_t *free_fn, void *pool_data)
270{
271 return mempool_create_node(min_nr, alloc_fn, free_fn, pool_data,
272 GFP_KERNEL, NUMA_NO_NODE);
273}
274EXPORT_SYMBOL(mempool_create);
275
276mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
277 mempool_free_t *free_fn, void *pool_data,
278 gfp_t gfp_mask, int node_id)
279{
280 mempool_t *pool;
281
282 pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
283 if (!pool)
284 return NULL;
285
286 if (mempool_init_node(pool, min_nr, alloc_fn, free_fn, pool_data,
287 gfp_mask, node_id)) {
288 kfree(pool);
289 return NULL;
290 }
291
292 return pool;
293}
294EXPORT_SYMBOL(mempool_create_node);
295
296/**
297 * mempool_resize - resize an existing memory pool
298 * @pool: pointer to the memory pool which was allocated via
299 * mempool_create().
300 * @new_min_nr: the new minimum number of elements guaranteed to be
301 * allocated for this pool.
302 *
303 * This function shrinks/grows the pool. In the case of growing,
304 * it cannot be guaranteed that the pool will be grown to the new
305 * size immediately, but new mempool_free() calls will refill it.
306 * This function may sleep.
307 *
308 * Note, the caller must guarantee that no mempool_destroy is called
309 * while this function is running. mempool_alloc() & mempool_free()
310 * might be called (eg. from IRQ contexts) while this function executes.
311 *
312 * Return: %0 on success, negative error code otherwise.
313 */
314int mempool_resize(mempool_t *pool, int new_min_nr)
315{
316 void *element;
317 void **new_elements;
318 unsigned long flags;
319
320 BUG_ON(new_min_nr <= 0);
321 might_sleep();
322
323 spin_lock_irqsave(&pool->lock, flags);
324 if (new_min_nr <= pool->min_nr) {
325 while (new_min_nr < pool->curr_nr) {
326 element = remove_element(pool);
327 spin_unlock_irqrestore(&pool->lock, flags);
328 pool->free(element, pool->pool_data);
329 spin_lock_irqsave(&pool->lock, flags);
330 }
331 pool->min_nr = new_min_nr;
332 goto out_unlock;
333 }
334 spin_unlock_irqrestore(&pool->lock, flags);
335
336 /* Grow the pool */
337 new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements),
338 GFP_KERNEL);
339 if (!new_elements)
340 return -ENOMEM;
341
342 spin_lock_irqsave(&pool->lock, flags);
343 if (unlikely(new_min_nr <= pool->min_nr)) {
344 /* Raced, other resize will do our work */
345 spin_unlock_irqrestore(&pool->lock, flags);
346 kfree(new_elements);
347 goto out;
348 }
349 memcpy(new_elements, pool->elements,
350 pool->curr_nr * sizeof(*new_elements));
351 kfree(pool->elements);
352 pool->elements = new_elements;
353 pool->min_nr = new_min_nr;
354
355 while (pool->curr_nr < pool->min_nr) {
356 spin_unlock_irqrestore(&pool->lock, flags);
357 element = pool->alloc(GFP_KERNEL, pool->pool_data);
358 if (!element)
359 goto out;
360 spin_lock_irqsave(&pool->lock, flags);
361 if (pool->curr_nr < pool->min_nr) {
362 add_element(pool, element);
363 } else {
364 spin_unlock_irqrestore(&pool->lock, flags);
365 pool->free(element, pool->pool_data); /* Raced */
366 goto out;
367 }
368 }
369out_unlock:
370 spin_unlock_irqrestore(&pool->lock, flags);
371out:
372 return 0;
373}
374EXPORT_SYMBOL(mempool_resize);
375
376/**
377 * mempool_alloc - allocate an element from a specific memory pool
378 * @pool: pointer to the memory pool which was allocated via
379 * mempool_create().
380 * @gfp_mask: the usual allocation bitmask.
381 *
382 * this function only sleeps if the alloc_fn() function sleeps or
383 * returns NULL. Note that due to preallocation, this function
384 * *never* fails when called from process contexts. (it might
385 * fail if called from an IRQ context.)
386 * Note: using __GFP_ZERO is not supported.
387 *
388 * Return: pointer to the allocated element or %NULL on error.
389 */
390void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
391{
392 void *element;
393 unsigned long flags;
394 wait_queue_entry_t wait;
395 gfp_t gfp_temp;
396
397 VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
398 might_alloc(gfp_mask);
399
400 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
401 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
402 gfp_mask |= __GFP_NOWARN; /* failures are OK */
403
404 gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
405
406repeat_alloc:
407
408 element = pool->alloc(gfp_temp, pool->pool_data);
409 if (likely(element != NULL))
410 return element;
411
412 spin_lock_irqsave(&pool->lock, flags);
413 if (likely(pool->curr_nr)) {
414 element = remove_element(pool);
415 spin_unlock_irqrestore(&pool->lock, flags);
416 /* paired with rmb in mempool_free(), read comment there */
417 smp_wmb();
418 /*
419 * Update the allocation stack trace as this is more useful
420 * for debugging.
421 */
422 kmemleak_update_trace(element);
423 return element;
424 }
425
426 /*
427 * We use gfp mask w/o direct reclaim or IO for the first round. If
428 * alloc failed with that and @pool was empty, retry immediately.
429 */
430 if (gfp_temp != gfp_mask) {
431 spin_unlock_irqrestore(&pool->lock, flags);
432 gfp_temp = gfp_mask;
433 goto repeat_alloc;
434 }
435
436 /* We must not sleep if !__GFP_DIRECT_RECLAIM */
437 if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
438 spin_unlock_irqrestore(&pool->lock, flags);
439 return NULL;
440 }
441
442 /* Let's wait for someone else to return an element to @pool */
443 init_wait(&wait);
444 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
445
446 spin_unlock_irqrestore(&pool->lock, flags);
447
448 /*
449 * FIXME: this should be io_schedule(). The timeout is there as a
450 * workaround for some DM problems in 2.6.18.
451 */
452 io_schedule_timeout(5*HZ);
453
454 finish_wait(&pool->wait, &wait);
455 goto repeat_alloc;
456}
457EXPORT_SYMBOL(mempool_alloc);
458
459/**
460 * mempool_alloc_preallocated - allocate an element from preallocated elements
461 * belonging to a specific memory pool
462 * @pool: pointer to the memory pool which was allocated via
463 * mempool_create().
464 *
465 * This function is similar to mempool_alloc, but it only attempts allocating
466 * an element from the preallocated elements. It does not sleep and immediately
467 * returns if no preallocated elements are available.
468 *
469 * Return: pointer to the allocated element or %NULL if no elements are
470 * available.
471 */
472void *mempool_alloc_preallocated(mempool_t *pool)
473{
474 void *element;
475 unsigned long flags;
476
477 spin_lock_irqsave(&pool->lock, flags);
478 if (likely(pool->curr_nr)) {
479 element = remove_element(pool);
480 spin_unlock_irqrestore(&pool->lock, flags);
481 /* paired with rmb in mempool_free(), read comment there */
482 smp_wmb();
483 /*
484 * Update the allocation stack trace as this is more useful
485 * for debugging.
486 */
487 kmemleak_update_trace(element);
488 return element;
489 }
490 spin_unlock_irqrestore(&pool->lock, flags);
491
492 return NULL;
493}
494EXPORT_SYMBOL(mempool_alloc_preallocated);
495
496/**
497 * mempool_free - return an element to the pool.
498 * @element: pool element pointer.
499 * @pool: pointer to the memory pool which was allocated via
500 * mempool_create().
501 *
502 * this function only sleeps if the free_fn() function sleeps.
503 */
504void mempool_free(void *element, mempool_t *pool)
505{
506 unsigned long flags;
507
508 if (unlikely(element == NULL))
509 return;
510
511 /*
512 * Paired with the wmb in mempool_alloc(). The preceding read is
513 * for @element and the following @pool->curr_nr. This ensures
514 * that the visible value of @pool->curr_nr is from after the
515 * allocation of @element. This is necessary for fringe cases
516 * where @element was passed to this task without going through
517 * barriers.
518 *
519 * For example, assume @p is %NULL at the beginning and one task
520 * performs "p = mempool_alloc(...);" while another task is doing
521 * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
522 * may end up using curr_nr value which is from before allocation
523 * of @p without the following rmb.
524 */
525 smp_rmb();
526
527 /*
528 * For correctness, we need a test which is guaranteed to trigger
529 * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
530 * without locking achieves that and refilling as soon as possible
531 * is desirable.
532 *
533 * Because curr_nr visible here is always a value after the
534 * allocation of @element, any task which decremented curr_nr below
535 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
536 * incremented to min_nr afterwards. If curr_nr gets incremented
537 * to min_nr after the allocation of @element, the elements
538 * allocated after that are subject to the same guarantee.
539 *
540 * Waiters happen iff curr_nr is 0 and the above guarantee also
541 * ensures that there will be frees which return elements to the
542 * pool waking up the waiters.
543 */
544 if (unlikely(READ_ONCE(pool->curr_nr) < pool->min_nr)) {
545 spin_lock_irqsave(&pool->lock, flags);
546 if (likely(pool->curr_nr < pool->min_nr)) {
547 add_element(pool, element);
548 spin_unlock_irqrestore(&pool->lock, flags);
549 wake_up(&pool->wait);
550 return;
551 }
552 spin_unlock_irqrestore(&pool->lock, flags);
553 }
554 pool->free(element, pool->pool_data);
555}
556EXPORT_SYMBOL(mempool_free);
557
558/*
559 * A commonly used alloc and free fn.
560 */
561void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
562{
563 struct kmem_cache *mem = pool_data;
564 VM_BUG_ON(mem->ctor);
565 return kmem_cache_alloc(mem, gfp_mask);
566}
567EXPORT_SYMBOL(mempool_alloc_slab);
568
569void mempool_free_slab(void *element, void *pool_data)
570{
571 struct kmem_cache *mem = pool_data;
572 kmem_cache_free(mem, element);
573}
574EXPORT_SYMBOL(mempool_free_slab);
575
576/*
577 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
578 * specified by pool_data
579 */
580void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
581{
582 size_t size = (size_t)pool_data;
583 return kmalloc(size, gfp_mask);
584}
585EXPORT_SYMBOL(mempool_kmalloc);
586
587void mempool_kfree(void *element, void *pool_data)
588{
589 kfree(element);
590}
591EXPORT_SYMBOL(mempool_kfree);
592
593void *mempool_kvmalloc(gfp_t gfp_mask, void *pool_data)
594{
595 size_t size = (size_t)pool_data;
596 return kvmalloc(size, gfp_mask);
597}
598EXPORT_SYMBOL(mempool_kvmalloc);
599
600void mempool_kvfree(void *element, void *pool_data)
601{
602 kvfree(element);
603}
604EXPORT_SYMBOL(mempool_kvfree);
605
606/*
607 * A simple mempool-backed page allocator that allocates pages
608 * of the order specified by pool_data.
609 */
610void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
611{
612 int order = (int)(long)pool_data;
613 return alloc_pages(gfp_mask, order);
614}
615EXPORT_SYMBOL(mempool_alloc_pages);
616
617void mempool_free_pages(void *element, void *pool_data)
618{
619 int order = (int)(long)pool_data;
620 __free_pages(element, order);
621}
622EXPORT_SYMBOL(mempool_free_pages);