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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, gfp_t flags)
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, gfp_t flags)
131{
132 void *element = pool->elements[--pool->curr_nr];
133
134 BUG_ON(pool->curr_nr < 0);
135 kasan_unpoison_element(pool, element, flags);
136 check_element(pool, element);
137 return element;
138}
139
140/**
141 * mempool_destroy - deallocate a memory pool
142 * @pool: pointer to the memory pool which was allocated via
143 * mempool_create().
144 *
145 * Free all reserved elements in @pool and @pool itself. This function
146 * only sleeps if the free_fn() function sleeps.
147 */
148void mempool_destroy(mempool_t *pool)
149{
150 if (unlikely(!pool))
151 return;
152
153 while (pool->curr_nr) {
154 void *element = remove_element(pool, GFP_KERNEL);
155 pool->free(element, pool->pool_data);
156 }
157 kfree(pool->elements);
158 kfree(pool);
159}
160EXPORT_SYMBOL(mempool_destroy);
161
162/**
163 * mempool_create - create a memory pool
164 * @min_nr: the minimum number of elements guaranteed to be
165 * allocated for this pool.
166 * @alloc_fn: user-defined element-allocation function.
167 * @free_fn: user-defined element-freeing function.
168 * @pool_data: optional private data available to the user-defined functions.
169 *
170 * this function creates and allocates a guaranteed size, preallocated
171 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
172 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
173 * functions might sleep - as long as the mempool_alloc() function is not called
174 * from IRQ contexts.
175 */
176mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
177 mempool_free_t *free_fn, void *pool_data)
178{
179 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,
180 GFP_KERNEL, NUMA_NO_NODE);
181}
182EXPORT_SYMBOL(mempool_create);
183
184mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
185 mempool_free_t *free_fn, void *pool_data,
186 gfp_t gfp_mask, int node_id)
187{
188 mempool_t *pool;
189 pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
190 if (!pool)
191 return NULL;
192 pool->elements = kmalloc_array_node(min_nr, sizeof(void *),
193 gfp_mask, node_id);
194 if (!pool->elements) {
195 kfree(pool);
196 return NULL;
197 }
198 spin_lock_init(&pool->lock);
199 pool->min_nr = min_nr;
200 pool->pool_data = pool_data;
201 init_waitqueue_head(&pool->wait);
202 pool->alloc = alloc_fn;
203 pool->free = free_fn;
204
205 /*
206 * First pre-allocate the guaranteed number of buffers.
207 */
208 while (pool->curr_nr < pool->min_nr) {
209 void *element;
210
211 element = pool->alloc(gfp_mask, pool->pool_data);
212 if (unlikely(!element)) {
213 mempool_destroy(pool);
214 return NULL;
215 }
216 add_element(pool, element);
217 }
218 return pool;
219}
220EXPORT_SYMBOL(mempool_create_node);
221
222/**
223 * mempool_resize - resize an existing memory pool
224 * @pool: pointer to the memory pool which was allocated via
225 * mempool_create().
226 * @new_min_nr: the new minimum number of elements guaranteed to be
227 * allocated for this pool.
228 *
229 * This function shrinks/grows the pool. In the case of growing,
230 * it cannot be guaranteed that the pool will be grown to the new
231 * size immediately, but new mempool_free() calls will refill it.
232 * This function may sleep.
233 *
234 * Note, the caller must guarantee that no mempool_destroy is called
235 * while this function is running. mempool_alloc() & mempool_free()
236 * might be called (eg. from IRQ contexts) while this function executes.
237 */
238int mempool_resize(mempool_t *pool, int new_min_nr)
239{
240 void *element;
241 void **new_elements;
242 unsigned long flags;
243
244 BUG_ON(new_min_nr <= 0);
245 might_sleep();
246
247 spin_lock_irqsave(&pool->lock, flags);
248 if (new_min_nr <= pool->min_nr) {
249 while (new_min_nr < pool->curr_nr) {
250 element = remove_element(pool, GFP_KERNEL);
251 spin_unlock_irqrestore(&pool->lock, flags);
252 pool->free(element, pool->pool_data);
253 spin_lock_irqsave(&pool->lock, flags);
254 }
255 pool->min_nr = new_min_nr;
256 goto out_unlock;
257 }
258 spin_unlock_irqrestore(&pool->lock, flags);
259
260 /* Grow the pool */
261 new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements),
262 GFP_KERNEL);
263 if (!new_elements)
264 return -ENOMEM;
265
266 spin_lock_irqsave(&pool->lock, flags);
267 if (unlikely(new_min_nr <= pool->min_nr)) {
268 /* Raced, other resize will do our work */
269 spin_unlock_irqrestore(&pool->lock, flags);
270 kfree(new_elements);
271 goto out;
272 }
273 memcpy(new_elements, pool->elements,
274 pool->curr_nr * sizeof(*new_elements));
275 kfree(pool->elements);
276 pool->elements = new_elements;
277 pool->min_nr = new_min_nr;
278
279 while (pool->curr_nr < pool->min_nr) {
280 spin_unlock_irqrestore(&pool->lock, flags);
281 element = pool->alloc(GFP_KERNEL, pool->pool_data);
282 if (!element)
283 goto out;
284 spin_lock_irqsave(&pool->lock, flags);
285 if (pool->curr_nr < pool->min_nr) {
286 add_element(pool, element);
287 } else {
288 spin_unlock_irqrestore(&pool->lock, flags);
289 pool->free(element, pool->pool_data); /* Raced */
290 goto out;
291 }
292 }
293out_unlock:
294 spin_unlock_irqrestore(&pool->lock, flags);
295out:
296 return 0;
297}
298EXPORT_SYMBOL(mempool_resize);
299
300/**
301 * mempool_alloc - allocate an element from a specific memory pool
302 * @pool: pointer to the memory pool which was allocated via
303 * mempool_create().
304 * @gfp_mask: the usual allocation bitmask.
305 *
306 * this function only sleeps if the alloc_fn() function sleeps or
307 * returns NULL. Note that due to preallocation, this function
308 * *never* fails when called from process contexts. (it might
309 * fail if called from an IRQ context.)
310 * Note: using __GFP_ZERO is not supported.
311 */
312void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
313{
314 void *element;
315 unsigned long flags;
316 wait_queue_entry_t wait;
317 gfp_t gfp_temp;
318
319 VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
320 might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
321
322 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
323 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
324 gfp_mask |= __GFP_NOWARN; /* failures are OK */
325
326 gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
327
328repeat_alloc:
329
330 element = pool->alloc(gfp_temp, pool->pool_data);
331 if (likely(element != NULL))
332 return element;
333
334 spin_lock_irqsave(&pool->lock, flags);
335 if (likely(pool->curr_nr)) {
336 element = remove_element(pool, gfp_temp);
337 spin_unlock_irqrestore(&pool->lock, flags);
338 /* paired with rmb in mempool_free(), read comment there */
339 smp_wmb();
340 /*
341 * Update the allocation stack trace as this is more useful
342 * for debugging.
343 */
344 kmemleak_update_trace(element);
345 return element;
346 }
347
348 /*
349 * We use gfp mask w/o direct reclaim or IO for the first round. If
350 * alloc failed with that and @pool was empty, retry immediately.
351 */
352 if (gfp_temp != gfp_mask) {
353 spin_unlock_irqrestore(&pool->lock, flags);
354 gfp_temp = gfp_mask;
355 goto repeat_alloc;
356 }
357
358 /* We must not sleep if !__GFP_DIRECT_RECLAIM */
359 if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
360 spin_unlock_irqrestore(&pool->lock, flags);
361 return NULL;
362 }
363
364 /* Let's wait for someone else to return an element to @pool */
365 init_wait(&wait);
366 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
367
368 spin_unlock_irqrestore(&pool->lock, flags);
369
370 /*
371 * FIXME: this should be io_schedule(). The timeout is there as a
372 * workaround for some DM problems in 2.6.18.
373 */
374 io_schedule_timeout(5*HZ);
375
376 finish_wait(&pool->wait, &wait);
377 goto repeat_alloc;
378}
379EXPORT_SYMBOL(mempool_alloc);
380
381/**
382 * mempool_free - return an element to the pool.
383 * @element: pool element pointer.
384 * @pool: pointer to the memory pool which was allocated via
385 * mempool_create().
386 *
387 * this function only sleeps if the free_fn() function sleeps.
388 */
389void mempool_free(void *element, mempool_t *pool)
390{
391 unsigned long flags;
392
393 if (unlikely(element == NULL))
394 return;
395
396 /*
397 * Paired with the wmb in mempool_alloc(). The preceding read is
398 * for @element and the following @pool->curr_nr. This ensures
399 * that the visible value of @pool->curr_nr is from after the
400 * allocation of @element. This is necessary for fringe cases
401 * where @element was passed to this task without going through
402 * barriers.
403 *
404 * For example, assume @p is %NULL at the beginning and one task
405 * performs "p = mempool_alloc(...);" while another task is doing
406 * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
407 * may end up using curr_nr value which is from before allocation
408 * of @p without the following rmb.
409 */
410 smp_rmb();
411
412 /*
413 * For correctness, we need a test which is guaranteed to trigger
414 * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
415 * without locking achieves that and refilling as soon as possible
416 * is desirable.
417 *
418 * Because curr_nr visible here is always a value after the
419 * allocation of @element, any task which decremented curr_nr below
420 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
421 * incremented to min_nr afterwards. If curr_nr gets incremented
422 * to min_nr after the allocation of @element, the elements
423 * allocated after that are subject to the same guarantee.
424 *
425 * Waiters happen iff curr_nr is 0 and the above guarantee also
426 * ensures that there will be frees which return elements to the
427 * pool waking up the waiters.
428 */
429 if (unlikely(pool->curr_nr < pool->min_nr)) {
430 spin_lock_irqsave(&pool->lock, flags);
431 if (likely(pool->curr_nr < pool->min_nr)) {
432 add_element(pool, element);
433 spin_unlock_irqrestore(&pool->lock, flags);
434 wake_up(&pool->wait);
435 return;
436 }
437 spin_unlock_irqrestore(&pool->lock, flags);
438 }
439 pool->free(element, pool->pool_data);
440}
441EXPORT_SYMBOL(mempool_free);
442
443/*
444 * A commonly used alloc and free fn.
445 */
446void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
447{
448 struct kmem_cache *mem = pool_data;
449 VM_BUG_ON(mem->ctor);
450 return kmem_cache_alloc(mem, gfp_mask);
451}
452EXPORT_SYMBOL(mempool_alloc_slab);
453
454void mempool_free_slab(void *element, void *pool_data)
455{
456 struct kmem_cache *mem = pool_data;
457 kmem_cache_free(mem, element);
458}
459EXPORT_SYMBOL(mempool_free_slab);
460
461/*
462 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
463 * specified by pool_data
464 */
465void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
466{
467 size_t size = (size_t)pool_data;
468 return kmalloc(size, gfp_mask);
469}
470EXPORT_SYMBOL(mempool_kmalloc);
471
472void mempool_kfree(void *element, void *pool_data)
473{
474 kfree(element);
475}
476EXPORT_SYMBOL(mempool_kfree);
477
478/*
479 * A simple mempool-backed page allocator that allocates pages
480 * of the order specified by pool_data.
481 */
482void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
483{
484 int order = (int)(long)pool_data;
485 return alloc_pages(gfp_mask, order);
486}
487EXPORT_SYMBOL(mempool_alloc_pages);
488
489void mempool_free_pages(void *element, void *pool_data)
490{
491 int order = (int)(long)pool_data;
492 __free_pages(element, order);
493}
494EXPORT_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#if defined(CONFIG_DEBUG_SLAB) || defined(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 /* Mempools backed by slab allocator */
60 if (pool->free == mempool_kfree) {
61 __check_element(pool, element, (size_t)pool->pool_data);
62 } else if (pool->free == mempool_free_slab) {
63 __check_element(pool, element, kmem_cache_size(pool->pool_data));
64 } else if (pool->free == mempool_free_pages) {
65 /* Mempools backed by page allocator */
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_kmalloc) {
86 __poison_element(element, (size_t)pool->pool_data);
87 } else if (pool->alloc == mempool_alloc_slab) {
88 __poison_element(element, kmem_cache_size(pool->pool_data));
89 } else if (pool->alloc == mempool_alloc_pages) {
90 /* Mempools backed by page allocator */
91 int order = (int)(long)pool->pool_data;
92 void *addr = kmap_atomic((struct page *)element);
93
94 __poison_element(addr, 1UL << (PAGE_SHIFT + order));
95 kunmap_atomic(addr);
96 }
97}
98#else /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
99static inline void check_element(mempool_t *pool, void *element)
100{
101}
102static inline void poison_element(mempool_t *pool, void *element)
103{
104}
105#endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
106
107static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
108{
109 if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
110 kasan_slab_free_mempool(element);
111 else if (pool->alloc == mempool_alloc_pages)
112 kasan_poison_pages(element, (unsigned long)pool->pool_data,
113 false);
114}
115
116static void kasan_unpoison_element(mempool_t *pool, void *element)
117{
118 if (pool->alloc == mempool_kmalloc)
119 kasan_unpoison_range(element, (size_t)pool->pool_data);
120 else if (pool->alloc == mempool_alloc_slab)
121 kasan_unpoison_range(element, kmem_cache_size(pool->pool_data));
122 else if (pool->alloc == mempool_alloc_pages)
123 kasan_unpoison_pages(element, (unsigned long)pool->pool_data,
124 false);
125}
126
127static __always_inline void add_element(mempool_t *pool, void *element)
128{
129 BUG_ON(pool->curr_nr >= pool->min_nr);
130 poison_element(pool, element);
131 kasan_poison_element(pool, element);
132 pool->elements[pool->curr_nr++] = element;
133}
134
135static void *remove_element(mempool_t *pool)
136{
137 void *element = pool->elements[--pool->curr_nr];
138
139 BUG_ON(pool->curr_nr < 0);
140 kasan_unpoison_element(pool, element);
141 check_element(pool, element);
142 return element;
143}
144
145/**
146 * mempool_exit - exit a mempool initialized with mempool_init()
147 * @pool: pointer to the memory pool which was initialized with
148 * mempool_init().
149 *
150 * Free all reserved elements in @pool and @pool itself. This function
151 * only sleeps if the free_fn() function sleeps.
152 *
153 * May be called on a zeroed but uninitialized mempool (i.e. allocated with
154 * kzalloc()).
155 */
156void mempool_exit(mempool_t *pool)
157{
158 while (pool->curr_nr) {
159 void *element = remove_element(pool);
160 pool->free(element, pool->pool_data);
161 }
162 kfree(pool->elements);
163 pool->elements = NULL;
164}
165EXPORT_SYMBOL(mempool_exit);
166
167/**
168 * mempool_destroy - deallocate a memory pool
169 * @pool: pointer to the memory pool which was allocated via
170 * mempool_create().
171 *
172 * Free all reserved elements in @pool and @pool itself. This function
173 * only sleeps if the free_fn() function sleeps.
174 */
175void mempool_destroy(mempool_t *pool)
176{
177 if (unlikely(!pool))
178 return;
179
180 mempool_exit(pool);
181 kfree(pool);
182}
183EXPORT_SYMBOL(mempool_destroy);
184
185int mempool_init_node(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
186 mempool_free_t *free_fn, void *pool_data,
187 gfp_t gfp_mask, int node_id)
188{
189 spin_lock_init(&pool->lock);
190 pool->min_nr = min_nr;
191 pool->pool_data = pool_data;
192 pool->alloc = alloc_fn;
193 pool->free = free_fn;
194 init_waitqueue_head(&pool->wait);
195
196 pool->elements = kmalloc_array_node(min_nr, sizeof(void *),
197 gfp_mask, node_id);
198 if (!pool->elements)
199 return -ENOMEM;
200
201 /*
202 * First pre-allocate the guaranteed number of buffers.
203 */
204 while (pool->curr_nr < pool->min_nr) {
205 void *element;
206
207 element = pool->alloc(gfp_mask, pool->pool_data);
208 if (unlikely(!element)) {
209 mempool_exit(pool);
210 return -ENOMEM;
211 }
212 add_element(pool, element);
213 }
214
215 return 0;
216}
217EXPORT_SYMBOL(mempool_init_node);
218
219/**
220 * mempool_init - initialize a memory pool
221 * @pool: pointer to the memory pool that should be initialized
222 * @min_nr: the minimum number of elements guaranteed to be
223 * allocated for this pool.
224 * @alloc_fn: user-defined element-allocation function.
225 * @free_fn: user-defined element-freeing function.
226 * @pool_data: optional private data available to the user-defined functions.
227 *
228 * Like mempool_create(), but initializes the pool in (i.e. embedded in another
229 * structure).
230 *
231 * Return: %0 on success, negative error code otherwise.
232 */
233int mempool_init(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
234 mempool_free_t *free_fn, void *pool_data)
235{
236 return mempool_init_node(pool, min_nr, alloc_fn, free_fn,
237 pool_data, GFP_KERNEL, NUMA_NO_NODE);
238
239}
240EXPORT_SYMBOL(mempool_init);
241
242/**
243 * mempool_create - create a memory pool
244 * @min_nr: the minimum number of elements guaranteed to be
245 * allocated for this pool.
246 * @alloc_fn: user-defined element-allocation function.
247 * @free_fn: user-defined element-freeing function.
248 * @pool_data: optional private data available to the user-defined functions.
249 *
250 * this function creates and allocates a guaranteed size, preallocated
251 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
252 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
253 * functions might sleep - as long as the mempool_alloc() function is not called
254 * from IRQ contexts.
255 *
256 * Return: pointer to the created memory pool object or %NULL on error.
257 */
258mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
259 mempool_free_t *free_fn, void *pool_data)
260{
261 return mempool_create_node(min_nr, alloc_fn, free_fn, pool_data,
262 GFP_KERNEL, NUMA_NO_NODE);
263}
264EXPORT_SYMBOL(mempool_create);
265
266mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
267 mempool_free_t *free_fn, void *pool_data,
268 gfp_t gfp_mask, int node_id)
269{
270 mempool_t *pool;
271
272 pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
273 if (!pool)
274 return NULL;
275
276 if (mempool_init_node(pool, min_nr, alloc_fn, free_fn, pool_data,
277 gfp_mask, node_id)) {
278 kfree(pool);
279 return NULL;
280 }
281
282 return pool;
283}
284EXPORT_SYMBOL(mempool_create_node);
285
286/**
287 * mempool_resize - resize an existing memory pool
288 * @pool: pointer to the memory pool which was allocated via
289 * mempool_create().
290 * @new_min_nr: the new minimum number of elements guaranteed to be
291 * allocated for this pool.
292 *
293 * This function shrinks/grows the pool. In the case of growing,
294 * it cannot be guaranteed that the pool will be grown to the new
295 * size immediately, but new mempool_free() calls will refill it.
296 * This function may sleep.
297 *
298 * Note, the caller must guarantee that no mempool_destroy is called
299 * while this function is running. mempool_alloc() & mempool_free()
300 * might be called (eg. from IRQ contexts) while this function executes.
301 *
302 * Return: %0 on success, negative error code otherwise.
303 */
304int mempool_resize(mempool_t *pool, int new_min_nr)
305{
306 void *element;
307 void **new_elements;
308 unsigned long flags;
309
310 BUG_ON(new_min_nr <= 0);
311 might_sleep();
312
313 spin_lock_irqsave(&pool->lock, flags);
314 if (new_min_nr <= pool->min_nr) {
315 while (new_min_nr < pool->curr_nr) {
316 element = remove_element(pool);
317 spin_unlock_irqrestore(&pool->lock, flags);
318 pool->free(element, pool->pool_data);
319 spin_lock_irqsave(&pool->lock, flags);
320 }
321 pool->min_nr = new_min_nr;
322 goto out_unlock;
323 }
324 spin_unlock_irqrestore(&pool->lock, flags);
325
326 /* Grow the pool */
327 new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements),
328 GFP_KERNEL);
329 if (!new_elements)
330 return -ENOMEM;
331
332 spin_lock_irqsave(&pool->lock, flags);
333 if (unlikely(new_min_nr <= pool->min_nr)) {
334 /* Raced, other resize will do our work */
335 spin_unlock_irqrestore(&pool->lock, flags);
336 kfree(new_elements);
337 goto out;
338 }
339 memcpy(new_elements, pool->elements,
340 pool->curr_nr * sizeof(*new_elements));
341 kfree(pool->elements);
342 pool->elements = new_elements;
343 pool->min_nr = new_min_nr;
344
345 while (pool->curr_nr < pool->min_nr) {
346 spin_unlock_irqrestore(&pool->lock, flags);
347 element = pool->alloc(GFP_KERNEL, pool->pool_data);
348 if (!element)
349 goto out;
350 spin_lock_irqsave(&pool->lock, flags);
351 if (pool->curr_nr < pool->min_nr) {
352 add_element(pool, element);
353 } else {
354 spin_unlock_irqrestore(&pool->lock, flags);
355 pool->free(element, pool->pool_data); /* Raced */
356 goto out;
357 }
358 }
359out_unlock:
360 spin_unlock_irqrestore(&pool->lock, flags);
361out:
362 return 0;
363}
364EXPORT_SYMBOL(mempool_resize);
365
366/**
367 * mempool_alloc - allocate an element from a specific memory pool
368 * @pool: pointer to the memory pool which was allocated via
369 * mempool_create().
370 * @gfp_mask: the usual allocation bitmask.
371 *
372 * this function only sleeps if the alloc_fn() function sleeps or
373 * returns NULL. Note that due to preallocation, this function
374 * *never* fails when called from process contexts. (it might
375 * fail if called from an IRQ context.)
376 * Note: using __GFP_ZERO is not supported.
377 *
378 * Return: pointer to the allocated element or %NULL on error.
379 */
380void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
381{
382 void *element;
383 unsigned long flags;
384 wait_queue_entry_t wait;
385 gfp_t gfp_temp;
386
387 VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
388 might_alloc(gfp_mask);
389
390 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
391 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
392 gfp_mask |= __GFP_NOWARN; /* failures are OK */
393
394 gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
395
396repeat_alloc:
397
398 element = pool->alloc(gfp_temp, pool->pool_data);
399 if (likely(element != NULL))
400 return element;
401
402 spin_lock_irqsave(&pool->lock, flags);
403 if (likely(pool->curr_nr)) {
404 element = remove_element(pool);
405 spin_unlock_irqrestore(&pool->lock, flags);
406 /* paired with rmb in mempool_free(), read comment there */
407 smp_wmb();
408 /*
409 * Update the allocation stack trace as this is more useful
410 * for debugging.
411 */
412 kmemleak_update_trace(element);
413 return element;
414 }
415
416 /*
417 * We use gfp mask w/o direct reclaim or IO for the first round. If
418 * alloc failed with that and @pool was empty, retry immediately.
419 */
420 if (gfp_temp != gfp_mask) {
421 spin_unlock_irqrestore(&pool->lock, flags);
422 gfp_temp = gfp_mask;
423 goto repeat_alloc;
424 }
425
426 /* We must not sleep if !__GFP_DIRECT_RECLAIM */
427 if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
428 spin_unlock_irqrestore(&pool->lock, flags);
429 return NULL;
430 }
431
432 /* Let's wait for someone else to return an element to @pool */
433 init_wait(&wait);
434 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
435
436 spin_unlock_irqrestore(&pool->lock, flags);
437
438 /*
439 * FIXME: this should be io_schedule(). The timeout is there as a
440 * workaround for some DM problems in 2.6.18.
441 */
442 io_schedule_timeout(5*HZ);
443
444 finish_wait(&pool->wait, &wait);
445 goto repeat_alloc;
446}
447EXPORT_SYMBOL(mempool_alloc);
448
449/**
450 * mempool_free - return an element to the pool.
451 * @element: pool element pointer.
452 * @pool: pointer to the memory pool which was allocated via
453 * mempool_create().
454 *
455 * this function only sleeps if the free_fn() function sleeps.
456 */
457void mempool_free(void *element, mempool_t *pool)
458{
459 unsigned long flags;
460
461 if (unlikely(element == NULL))
462 return;
463
464 /*
465 * Paired with the wmb in mempool_alloc(). The preceding read is
466 * for @element and the following @pool->curr_nr. This ensures
467 * that the visible value of @pool->curr_nr is from after the
468 * allocation of @element. This is necessary for fringe cases
469 * where @element was passed to this task without going through
470 * barriers.
471 *
472 * For example, assume @p is %NULL at the beginning and one task
473 * performs "p = mempool_alloc(...);" while another task is doing
474 * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
475 * may end up using curr_nr value which is from before allocation
476 * of @p without the following rmb.
477 */
478 smp_rmb();
479
480 /*
481 * For correctness, we need a test which is guaranteed to trigger
482 * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
483 * without locking achieves that and refilling as soon as possible
484 * is desirable.
485 *
486 * Because curr_nr visible here is always a value after the
487 * allocation of @element, any task which decremented curr_nr below
488 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
489 * incremented to min_nr afterwards. If curr_nr gets incremented
490 * to min_nr after the allocation of @element, the elements
491 * allocated after that are subject to the same guarantee.
492 *
493 * Waiters happen iff curr_nr is 0 and the above guarantee also
494 * ensures that there will be frees which return elements to the
495 * pool waking up the waiters.
496 */
497 if (unlikely(READ_ONCE(pool->curr_nr) < pool->min_nr)) {
498 spin_lock_irqsave(&pool->lock, flags);
499 if (likely(pool->curr_nr < pool->min_nr)) {
500 add_element(pool, element);
501 spin_unlock_irqrestore(&pool->lock, flags);
502 wake_up(&pool->wait);
503 return;
504 }
505 spin_unlock_irqrestore(&pool->lock, flags);
506 }
507 pool->free(element, pool->pool_data);
508}
509EXPORT_SYMBOL(mempool_free);
510
511/*
512 * A commonly used alloc and free fn.
513 */
514void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
515{
516 struct kmem_cache *mem = pool_data;
517 VM_BUG_ON(mem->ctor);
518 return kmem_cache_alloc(mem, gfp_mask);
519}
520EXPORT_SYMBOL(mempool_alloc_slab);
521
522void mempool_free_slab(void *element, void *pool_data)
523{
524 struct kmem_cache *mem = pool_data;
525 kmem_cache_free(mem, element);
526}
527EXPORT_SYMBOL(mempool_free_slab);
528
529/*
530 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
531 * specified by pool_data
532 */
533void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
534{
535 size_t size = (size_t)pool_data;
536 return kmalloc(size, gfp_mask);
537}
538EXPORT_SYMBOL(mempool_kmalloc);
539
540void mempool_kfree(void *element, void *pool_data)
541{
542 kfree(element);
543}
544EXPORT_SYMBOL(mempool_kfree);
545
546/*
547 * A simple mempool-backed page allocator that allocates pages
548 * of the order specified by pool_data.
549 */
550void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
551{
552 int order = (int)(long)pool_data;
553 return alloc_pages(gfp_mask, order);
554}
555EXPORT_SYMBOL(mempool_alloc_pages);
556
557void mempool_free_pages(void *element, void *pool_data)
558{
559 int order = (int)(long)pool_data;
560 __free_pages(element, order);
561}
562EXPORT_SYMBOL(mempool_free_pages);