Line data Source code
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)
25 : static 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 :
42 : static 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 :
58 : static 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 : } else if (pool->free == mempool_free_pages) {
64 : /* Mempools backed by page allocator */
65 : int order = (int)(long)pool->pool_data;
66 : void *addr = kmap_atomic((struct page *)element);
67 :
68 : __check_element(pool, addr, 1UL << (PAGE_SHIFT + order));
69 : kunmap_atomic(addr);
70 : }
71 : }
72 :
73 : static void __poison_element(void *element, size_t size)
74 : {
75 : u8 *obj = element;
76 :
77 : memset(obj, POISON_FREE, size - 1);
78 : obj[size - 1] = POISON_END;
79 : }
80 :
81 : static void poison_element(mempool_t *pool, void *element)
82 : {
83 : /* Mempools backed by slab allocator */
84 : if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc) {
85 : __poison_element(element, ksize(element));
86 : } else if (pool->alloc == mempool_alloc_pages) {
87 : /* Mempools backed by page allocator */
88 : int order = (int)(long)pool->pool_data;
89 : void *addr = kmap_atomic((struct page *)element);
90 :
91 : __poison_element(addr, 1UL << (PAGE_SHIFT + order));
92 : kunmap_atomic(addr);
93 : }
94 : }
95 : #else /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
96 0 : static inline void check_element(mempool_t *pool, void *element)
97 : {
98 0 : }
99 : static inline void poison_element(mempool_t *pool, void *element)
100 : {
101 : }
102 : #endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
103 :
104 300 : static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
105 : {
106 2 : if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
107 298 : kasan_slab_free_mempool(element);
108 2 : else if (pool->alloc == mempool_alloc_pages)
109 2 : kasan_free_pages(element, (unsigned long)pool->pool_data);
110 : }
111 :
112 0 : static void kasan_unpoison_element(mempool_t *pool, void *element)
113 : {
114 0 : if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
115 0 : kasan_unpoison_range(element, __ksize(element));
116 0 : else if (pool->alloc == mempool_alloc_pages)
117 0 : kasan_alloc_pages(element, (unsigned long)pool->pool_data);
118 0 : }
119 :
120 300 : static __always_inline void add_element(mempool_t *pool, void *element)
121 : {
122 0 : BUG_ON(pool->curr_nr >= pool->min_nr);
123 300 : poison_element(pool, element);
124 300 : kasan_poison_element(pool, element);
125 300 : pool->elements[pool->curr_nr++] = element;
126 300 : }
127 :
128 0 : static void *remove_element(mempool_t *pool)
129 : {
130 0 : void *element = pool->elements[--pool->curr_nr];
131 :
132 0 : BUG_ON(pool->curr_nr < 0);
133 0 : kasan_unpoison_element(pool, element);
134 0 : check_element(pool, element);
135 0 : return element;
136 : }
137 :
138 : /**
139 : * mempool_exit - exit a mempool initialized with mempool_init()
140 : * @pool: pointer to the memory pool which was initialized with
141 : * mempool_init().
142 : *
143 : * Free all reserved elements in @pool and @pool itself. This function
144 : * only sleeps if the free_fn() function sleeps.
145 : *
146 : * May be called on a zeroed but uninitialized mempool (i.e. allocated with
147 : * kzalloc()).
148 : */
149 0 : void mempool_exit(mempool_t *pool)
150 : {
151 0 : while (pool->curr_nr) {
152 0 : void *element = remove_element(pool);
153 0 : pool->free(element, pool->pool_data);
154 : }
155 0 : kfree(pool->elements);
156 0 : pool->elements = NULL;
157 0 : }
158 : EXPORT_SYMBOL(mempool_exit);
159 :
160 : /**
161 : * mempool_destroy - deallocate a memory pool
162 : * @pool: pointer to the memory pool which was allocated via
163 : * mempool_create().
164 : *
165 : * Free all reserved elements in @pool and @pool itself. This function
166 : * only sleeps if the free_fn() function sleeps.
167 : */
168 0 : void mempool_destroy(mempool_t *pool)
169 : {
170 0 : if (unlikely(!pool))
171 : return;
172 :
173 0 : mempool_exit(pool);
174 0 : kfree(pool);
175 : }
176 : EXPORT_SYMBOL(mempool_destroy);
177 :
178 24 : int mempool_init_node(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
179 : mempool_free_t *free_fn, void *pool_data,
180 : gfp_t gfp_mask, int node_id)
181 : {
182 24 : spin_lock_init(&pool->lock);
183 24 : pool->min_nr = min_nr;
184 24 : pool->pool_data = pool_data;
185 24 : pool->alloc = alloc_fn;
186 24 : pool->free = free_fn;
187 24 : init_waitqueue_head(&pool->wait);
188 :
189 24 : pool->elements = kmalloc_array_node(min_nr, sizeof(void *),
190 : gfp_mask, node_id);
191 24 : if (!pool->elements)
192 : return -ENOMEM;
193 :
194 : /*
195 : * First pre-allocate the guaranteed number of buffers.
196 : */
197 324 : while (pool->curr_nr < pool->min_nr) {
198 300 : void *element;
199 :
200 300 : element = pool->alloc(gfp_mask, pool->pool_data);
201 300 : if (unlikely(!element)) {
202 0 : mempool_exit(pool);
203 0 : return -ENOMEM;
204 : }
205 624 : add_element(pool, element);
206 : }
207 :
208 : return 0;
209 : }
210 : EXPORT_SYMBOL(mempool_init_node);
211 :
212 : /**
213 : * mempool_init - initialize a memory pool
214 : * @pool: pointer to the memory pool that should be initialized
215 : * @min_nr: the minimum number of elements guaranteed to be
216 : * allocated for this pool.
217 : * @alloc_fn: user-defined element-allocation function.
218 : * @free_fn: user-defined element-freeing function.
219 : * @pool_data: optional private data available to the user-defined functions.
220 : *
221 : * Like mempool_create(), but initializes the pool in (i.e. embedded in another
222 : * structure).
223 : *
224 : * Return: %0 on success, negative error code otherwise.
225 : */
226 15 : int mempool_init(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
227 : mempool_free_t *free_fn, void *pool_data)
228 : {
229 15 : return mempool_init_node(pool, min_nr, alloc_fn, free_fn,
230 : pool_data, GFP_KERNEL, NUMA_NO_NODE);
231 :
232 : }
233 : EXPORT_SYMBOL(mempool_init);
234 :
235 : /**
236 : * mempool_create - create a memory pool
237 : * @min_nr: the minimum number of elements guaranteed to be
238 : * allocated for this pool.
239 : * @alloc_fn: user-defined element-allocation function.
240 : * @free_fn: user-defined element-freeing function.
241 : * @pool_data: optional private data available to the user-defined functions.
242 : *
243 : * this function creates and allocates a guaranteed size, preallocated
244 : * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
245 : * functions. This function might sleep. Both the alloc_fn() and the free_fn()
246 : * functions might sleep - as long as the mempool_alloc() function is not called
247 : * from IRQ contexts.
248 : *
249 : * Return: pointer to the created memory pool object or %NULL on error.
250 : */
251 9 : mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
252 : mempool_free_t *free_fn, void *pool_data)
253 : {
254 9 : return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,
255 : GFP_KERNEL, NUMA_NO_NODE);
256 : }
257 : EXPORT_SYMBOL(mempool_create);
258 :
259 9 : mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
260 : mempool_free_t *free_fn, void *pool_data,
261 : gfp_t gfp_mask, int node_id)
262 : {
263 9 : mempool_t *pool;
264 :
265 9 : pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
266 9 : if (!pool)
267 : return NULL;
268 :
269 9 : if (mempool_init_node(pool, min_nr, alloc_fn, free_fn, pool_data,
270 : gfp_mask, node_id)) {
271 0 : kfree(pool);
272 0 : return NULL;
273 : }
274 :
275 : return pool;
276 : }
277 : EXPORT_SYMBOL(mempool_create_node);
278 :
279 : /**
280 : * mempool_resize - resize an existing memory pool
281 : * @pool: pointer to the memory pool which was allocated via
282 : * mempool_create().
283 : * @new_min_nr: the new minimum number of elements guaranteed to be
284 : * allocated for this pool.
285 : *
286 : * This function shrinks/grows the pool. In the case of growing,
287 : * it cannot be guaranteed that the pool will be grown to the new
288 : * size immediately, but new mempool_free() calls will refill it.
289 : * This function may sleep.
290 : *
291 : * Note, the caller must guarantee that no mempool_destroy is called
292 : * while this function is running. mempool_alloc() & mempool_free()
293 : * might be called (eg. from IRQ contexts) while this function executes.
294 : *
295 : * Return: %0 on success, negative error code otherwise.
296 : */
297 0 : int mempool_resize(mempool_t *pool, int new_min_nr)
298 : {
299 0 : void *element;
300 0 : void **new_elements;
301 0 : unsigned long flags;
302 :
303 0 : BUG_ON(new_min_nr <= 0);
304 0 : might_sleep();
305 :
306 0 : spin_lock_irqsave(&pool->lock, flags);
307 0 : if (new_min_nr <= pool->min_nr) {
308 0 : while (new_min_nr < pool->curr_nr) {
309 0 : element = remove_element(pool);
310 0 : spin_unlock_irqrestore(&pool->lock, flags);
311 0 : pool->free(element, pool->pool_data);
312 0 : spin_lock_irqsave(&pool->lock, flags);
313 : }
314 0 : pool->min_nr = new_min_nr;
315 0 : goto out_unlock;
316 : }
317 0 : spin_unlock_irqrestore(&pool->lock, flags);
318 :
319 : /* Grow the pool */
320 0 : new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements),
321 : GFP_KERNEL);
322 0 : if (!new_elements)
323 : return -ENOMEM;
324 :
325 0 : spin_lock_irqsave(&pool->lock, flags);
326 0 : if (unlikely(new_min_nr <= pool->min_nr)) {
327 : /* Raced, other resize will do our work */
328 0 : spin_unlock_irqrestore(&pool->lock, flags);
329 0 : kfree(new_elements);
330 0 : goto out;
331 : }
332 0 : memcpy(new_elements, pool->elements,
333 0 : pool->curr_nr * sizeof(*new_elements));
334 0 : kfree(pool->elements);
335 0 : pool->elements = new_elements;
336 0 : pool->min_nr = new_min_nr;
337 :
338 0 : while (pool->curr_nr < pool->min_nr) {
339 0 : spin_unlock_irqrestore(&pool->lock, flags);
340 0 : element = pool->alloc(GFP_KERNEL, pool->pool_data);
341 0 : if (!element)
342 0 : goto out;
343 0 : spin_lock_irqsave(&pool->lock, flags);
344 0 : if (pool->curr_nr < pool->min_nr) {
345 0 : add_element(pool, element);
346 : } else {
347 0 : spin_unlock_irqrestore(&pool->lock, flags);
348 0 : pool->free(element, pool->pool_data); /* Raced */
349 0 : goto out;
350 : }
351 : }
352 0 : out_unlock:
353 0 : spin_unlock_irqrestore(&pool->lock, flags);
354 : out:
355 : return 0;
356 : }
357 : EXPORT_SYMBOL(mempool_resize);
358 :
359 : /**
360 : * mempool_alloc - allocate an element from a specific memory pool
361 : * @pool: pointer to the memory pool which was allocated via
362 : * mempool_create().
363 : * @gfp_mask: the usual allocation bitmask.
364 : *
365 : * this function only sleeps if the alloc_fn() function sleeps or
366 : * returns NULL. Note that due to preallocation, this function
367 : * *never* fails when called from process contexts. (it might
368 : * fail if called from an IRQ context.)
369 : * Note: using __GFP_ZERO is not supported.
370 : *
371 : * Return: pointer to the allocated element or %NULL on error.
372 : */
373 8650 : void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
374 : {
375 8650 : void *element;
376 8650 : unsigned long flags;
377 8650 : wait_queue_entry_t wait;
378 8650 : gfp_t gfp_temp;
379 :
380 8650 : VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO);
381 8650 : might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM);
382 :
383 8650 : gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
384 8650 : gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
385 8650 : gfp_mask |= __GFP_NOWARN; /* failures are OK */
386 :
387 8650 : gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
388 :
389 : repeat_alloc:
390 :
391 8650 : element = pool->alloc(gfp_temp, pool->pool_data);
392 8650 : if (likely(element != NULL))
393 8650 : return element;
394 :
395 0 : spin_lock_irqsave(&pool->lock, flags);
396 0 : if (likely(pool->curr_nr)) {
397 0 : element = remove_element(pool);
398 0 : spin_unlock_irqrestore(&pool->lock, flags);
399 : /* paired with rmb in mempool_free(), read comment there */
400 0 : smp_wmb();
401 : /*
402 : * Update the allocation stack trace as this is more useful
403 : * for debugging.
404 : */
405 0 : kmemleak_update_trace(element);
406 0 : return element;
407 : }
408 :
409 : /*
410 : * We use gfp mask w/o direct reclaim or IO for the first round. If
411 : * alloc failed with that and @pool was empty, retry immediately.
412 : */
413 0 : if (gfp_temp != gfp_mask) {
414 0 : spin_unlock_irqrestore(&pool->lock, flags);
415 0 : gfp_temp = gfp_mask;
416 0 : goto repeat_alloc;
417 : }
418 :
419 : /* We must not sleep if !__GFP_DIRECT_RECLAIM */
420 0 : if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
421 0 : spin_unlock_irqrestore(&pool->lock, flags);
422 0 : return NULL;
423 : }
424 :
425 : /* Let's wait for someone else to return an element to @pool */
426 0 : init_wait(&wait);
427 0 : prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
428 :
429 0 : spin_unlock_irqrestore(&pool->lock, flags);
430 :
431 : /*
432 : * FIXME: this should be io_schedule(). The timeout is there as a
433 : * workaround for some DM problems in 2.6.18.
434 : */
435 0 : io_schedule_timeout(5*HZ);
436 :
437 0 : finish_wait(&pool->wait, &wait);
438 0 : goto repeat_alloc;
439 : }
440 : EXPORT_SYMBOL(mempool_alloc);
441 :
442 : /**
443 : * mempool_free - return an element to the pool.
444 : * @element: pool element pointer.
445 : * @pool: pointer to the memory pool which was allocated via
446 : * mempool_create().
447 : *
448 : * this function only sleeps if the free_fn() function sleeps.
449 : */
450 8650 : void mempool_free(void *element, mempool_t *pool)
451 : {
452 8650 : unsigned long flags;
453 :
454 8650 : if (unlikely(element == NULL))
455 : return;
456 :
457 : /*
458 : * Paired with the wmb in mempool_alloc(). The preceding read is
459 : * for @element and the following @pool->curr_nr. This ensures
460 : * that the visible value of @pool->curr_nr is from after the
461 : * allocation of @element. This is necessary for fringe cases
462 : * where @element was passed to this task without going through
463 : * barriers.
464 : *
465 : * For example, assume @p is %NULL at the beginning and one task
466 : * performs "p = mempool_alloc(...);" while another task is doing
467 : * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
468 : * may end up using curr_nr value which is from before allocation
469 : * of @p without the following rmb.
470 : */
471 8650 : smp_rmb();
472 :
473 : /*
474 : * For correctness, we need a test which is guaranteed to trigger
475 : * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
476 : * without locking achieves that and refilling as soon as possible
477 : * is desirable.
478 : *
479 : * Because curr_nr visible here is always a value after the
480 : * allocation of @element, any task which decremented curr_nr below
481 : * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
482 : * incremented to min_nr afterwards. If curr_nr gets incremented
483 : * to min_nr after the allocation of @element, the elements
484 : * allocated after that are subject to the same guarantee.
485 : *
486 : * Waiters happen iff curr_nr is 0 and the above guarantee also
487 : * ensures that there will be frees which return elements to the
488 : * pool waking up the waiters.
489 : */
490 8650 : if (unlikely(READ_ONCE(pool->curr_nr) < pool->min_nr)) {
491 0 : spin_lock_irqsave(&pool->lock, flags);
492 0 : if (likely(pool->curr_nr < pool->min_nr)) {
493 0 : add_element(pool, element);
494 0 : spin_unlock_irqrestore(&pool->lock, flags);
495 0 : wake_up(&pool->wait);
496 0 : return;
497 : }
498 0 : spin_unlock_irqrestore(&pool->lock, flags);
499 : }
500 8650 : pool->free(element, pool->pool_data);
501 : }
502 : EXPORT_SYMBOL(mempool_free);
503 :
504 : /*
505 : * A commonly used alloc and free fn.
506 : */
507 8948 : void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
508 : {
509 8948 : struct kmem_cache *mem = pool_data;
510 8948 : VM_BUG_ON(mem->ctor);
511 8948 : return kmem_cache_alloc(mem, gfp_mask);
512 : }
513 : EXPORT_SYMBOL(mempool_alloc_slab);
514 :
515 8650 : void mempool_free_slab(void *element, void *pool_data)
516 : {
517 8650 : struct kmem_cache *mem = pool_data;
518 8650 : kmem_cache_free(mem, element);
519 8650 : }
520 : EXPORT_SYMBOL(mempool_free_slab);
521 :
522 : /*
523 : * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
524 : * specified by pool_data
525 : */
526 0 : void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
527 : {
528 0 : size_t size = (size_t)pool_data;
529 0 : return kmalloc(size, gfp_mask);
530 : }
531 : EXPORT_SYMBOL(mempool_kmalloc);
532 :
533 0 : void mempool_kfree(void *element, void *pool_data)
534 : {
535 0 : kfree(element);
536 0 : }
537 : EXPORT_SYMBOL(mempool_kfree);
538 :
539 : /*
540 : * A simple mempool-backed page allocator that allocates pages
541 : * of the order specified by pool_data.
542 : */
543 2 : void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
544 : {
545 2 : int order = (int)(long)pool_data;
546 2 : return alloc_pages(gfp_mask, order);
547 : }
548 : EXPORT_SYMBOL(mempool_alloc_pages);
549 :
550 0 : void mempool_free_pages(void *element, void *pool_data)
551 : {
552 0 : int order = (int)(long)pool_data;
553 0 : __free_pages(element, order);
554 0 : }
555 : EXPORT_SYMBOL(mempool_free_pages);
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