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/writeback.h>
21 : #include "slab.h"
22 :
23 : #if defined(CONFIG_DEBUG_SLAB) || defined(CONFIG_SLUB_DEBUG_ON)
24 : static 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 :
41 : static 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 :
57 : static 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 :
74 : static 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 :
82 : static 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 */
99 : static inline void check_element(mempool_t *pool, void *element)
100 : {
101 : }
102 : static inline void poison_element(mempool_t *pool, void *element)
103 : {
104 : }
105 : #endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */
106 :
107 : static __always_inline void kasan_poison_element(mempool_t *pool, void *element)
108 : {
109 : if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc)
110 12 : 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 :
116 : static void kasan_unpoison_element(mempool_t *pool, void *element)
117 : {
118 0 : if (pool->alloc == mempool_kmalloc)
119 : kasan_unpoison_range(element, (size_t)pool->pool_data);
120 0 : else if (pool->alloc == mempool_alloc_slab)
121 0 : 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 :
127 : static __always_inline void add_element(mempool_t *pool, void *element)
128 : {
129 12 : BUG_ON(pool->curr_nr >= pool->min_nr);
130 12 : poison_element(pool, element);
131 12 : kasan_poison_element(pool, element);
132 12 : pool->elements[pool->curr_nr++] = element;
133 : }
134 :
135 0 : static void *remove_element(mempool_t *pool)
136 : {
137 0 : void *element = pool->elements[--pool->curr_nr];
138 :
139 0 : BUG_ON(pool->curr_nr < 0);
140 0 : kasan_unpoison_element(pool, element);
141 0 : check_element(pool, element);
142 0 : 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 : */
156 0 : void mempool_exit(mempool_t *pool)
157 : {
158 0 : while (pool->curr_nr) {
159 0 : void *element = remove_element(pool);
160 0 : pool->free(element, pool->pool_data);
161 : }
162 0 : kfree(pool->elements);
163 0 : pool->elements = NULL;
164 0 : }
165 : EXPORT_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 : */
175 0 : void mempool_destroy(mempool_t *pool)
176 : {
177 0 : if (unlikely(!pool))
178 : return;
179 :
180 0 : mempool_exit(pool);
181 0 : kfree(pool);
182 : }
183 : EXPORT_SYMBOL(mempool_destroy);
184 :
185 4 : int 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 4 : spin_lock_init(&pool->lock);
190 4 : pool->min_nr = min_nr;
191 4 : pool->pool_data = pool_data;
192 4 : pool->alloc = alloc_fn;
193 4 : pool->free = free_fn;
194 4 : init_waitqueue_head(&pool->wait);
195 :
196 4 : pool->elements = kmalloc_array_node(min_nr, sizeof(void *),
197 : gfp_mask, node_id);
198 4 : if (!pool->elements)
199 : return -ENOMEM;
200 :
201 : /*
202 : * First pre-allocate the guaranteed number of buffers.
203 : */
204 16 : while (pool->curr_nr < pool->min_nr) {
205 : void *element;
206 :
207 12 : element = pool->alloc(gfp_mask, pool->pool_data);
208 12 : if (unlikely(!element)) {
209 0 : mempool_exit(pool);
210 0 : return -ENOMEM;
211 : }
212 : add_element(pool, element);
213 : }
214 :
215 : return 0;
216 : }
217 : EXPORT_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 : */
233 4 : int mempool_init(mempool_t *pool, int min_nr, mempool_alloc_t *alloc_fn,
234 : mempool_free_t *free_fn, void *pool_data)
235 : {
236 4 : return mempool_init_node(pool, min_nr, alloc_fn, free_fn,
237 : pool_data, GFP_KERNEL, NUMA_NO_NODE);
238 :
239 : }
240 : EXPORT_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 : */
258 0 : mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
259 : mempool_free_t *free_fn, void *pool_data)
260 : {
261 0 : return mempool_create_node(min_nr, alloc_fn, free_fn, pool_data,
262 : GFP_KERNEL, NUMA_NO_NODE);
263 : }
264 : EXPORT_SYMBOL(mempool_create);
265 :
266 0 : mempool_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 0 : pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
273 0 : if (!pool)
274 : return NULL;
275 :
276 0 : if (mempool_init_node(pool, min_nr, alloc_fn, free_fn, pool_data,
277 : gfp_mask, node_id)) {
278 0 : kfree(pool);
279 0 : return NULL;
280 : }
281 :
282 : return pool;
283 : }
284 : EXPORT_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 : */
304 0 : int mempool_resize(mempool_t *pool, int new_min_nr)
305 : {
306 : void *element;
307 : void **new_elements;
308 : unsigned long flags;
309 :
310 0 : BUG_ON(new_min_nr <= 0);
311 : might_sleep();
312 :
313 0 : spin_lock_irqsave(&pool->lock, flags);
314 0 : if (new_min_nr <= pool->min_nr) {
315 0 : while (new_min_nr < pool->curr_nr) {
316 0 : element = remove_element(pool);
317 0 : spin_unlock_irqrestore(&pool->lock, flags);
318 0 : pool->free(element, pool->pool_data);
319 0 : spin_lock_irqsave(&pool->lock, flags);
320 : }
321 0 : pool->min_nr = new_min_nr;
322 0 : goto out_unlock;
323 : }
324 0 : spin_unlock_irqrestore(&pool->lock, flags);
325 :
326 : /* Grow the pool */
327 0 : new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements),
328 : GFP_KERNEL);
329 0 : if (!new_elements)
330 : return -ENOMEM;
331 :
332 0 : spin_lock_irqsave(&pool->lock, flags);
333 0 : if (unlikely(new_min_nr <= pool->min_nr)) {
334 : /* Raced, other resize will do our work */
335 0 : spin_unlock_irqrestore(&pool->lock, flags);
336 0 : kfree(new_elements);
337 0 : goto out;
338 : }
339 0 : memcpy(new_elements, pool->elements,
340 0 : pool->curr_nr * sizeof(*new_elements));
341 0 : kfree(pool->elements);
342 0 : pool->elements = new_elements;
343 0 : pool->min_nr = new_min_nr;
344 :
345 0 : while (pool->curr_nr < pool->min_nr) {
346 0 : spin_unlock_irqrestore(&pool->lock, flags);
347 0 : element = pool->alloc(GFP_KERNEL, pool->pool_data);
348 0 : if (!element)
349 : goto out;
350 0 : spin_lock_irqsave(&pool->lock, flags);
351 0 : if (pool->curr_nr < pool->min_nr) {
352 : add_element(pool, element);
353 : } else {
354 0 : spin_unlock_irqrestore(&pool->lock, flags);
355 0 : pool->free(element, pool->pool_data); /* Raced */
356 0 : goto out;
357 : }
358 : }
359 : out_unlock:
360 0 : spin_unlock_irqrestore(&pool->lock, flags);
361 : out:
362 : return 0;
363 : }
364 : EXPORT_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 : */
380 0 : void *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 0 : might_alloc(gfp_mask);
389 :
390 0 : gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
391 0 : gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
392 0 : gfp_mask |= __GFP_NOWARN; /* failures are OK */
393 :
394 0 : gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO);
395 :
396 : repeat_alloc:
397 :
398 0 : element = pool->alloc(gfp_temp, pool->pool_data);
399 0 : if (likely(element != NULL))
400 : return element;
401 :
402 0 : spin_lock_irqsave(&pool->lock, flags);
403 0 : if (likely(pool->curr_nr)) {
404 0 : element = remove_element(pool);
405 0 : spin_unlock_irqrestore(&pool->lock, flags);
406 : /* paired with rmb in mempool_free(), read comment there */
407 0 : smp_wmb();
408 : /*
409 : * Update the allocation stack trace as this is more useful
410 : * for debugging.
411 : */
412 0 : kmemleak_update_trace(element);
413 0 : 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 0 : if (gfp_temp != gfp_mask) {
421 0 : spin_unlock_irqrestore(&pool->lock, flags);
422 0 : gfp_temp = gfp_mask;
423 0 : goto repeat_alloc;
424 : }
425 :
426 : /* We must not sleep if !__GFP_DIRECT_RECLAIM */
427 0 : if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) {
428 0 : spin_unlock_irqrestore(&pool->lock, flags);
429 0 : return NULL;
430 : }
431 :
432 : /* Let's wait for someone else to return an element to @pool */
433 0 : init_wait(&wait);
434 0 : prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
435 :
436 0 : 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 0 : io_schedule_timeout(5*HZ);
443 :
444 0 : finish_wait(&pool->wait, &wait);
445 0 : goto repeat_alloc;
446 : }
447 : EXPORT_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 : */
457 0 : void mempool_free(void *element, mempool_t *pool)
458 : {
459 : unsigned long flags;
460 :
461 0 : 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 0 : 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 0 : if (unlikely(READ_ONCE(pool->curr_nr) < pool->min_nr)) {
498 0 : spin_lock_irqsave(&pool->lock, flags);
499 0 : if (likely(pool->curr_nr < pool->min_nr)) {
500 0 : add_element(pool, element);
501 0 : spin_unlock_irqrestore(&pool->lock, flags);
502 0 : wake_up(&pool->wait);
503 0 : return;
504 : }
505 0 : spin_unlock_irqrestore(&pool->lock, flags);
506 : }
507 0 : pool->free(element, pool->pool_data);
508 : }
509 : EXPORT_SYMBOL(mempool_free);
510 :
511 : /*
512 : * A commonly used alloc and free fn.
513 : */
514 12 : void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
515 : {
516 12 : struct kmem_cache *mem = pool_data;
517 : VM_BUG_ON(mem->ctor);
518 12 : return kmem_cache_alloc(mem, gfp_mask);
519 : }
520 : EXPORT_SYMBOL(mempool_alloc_slab);
521 :
522 0 : void mempool_free_slab(void *element, void *pool_data)
523 : {
524 0 : struct kmem_cache *mem = pool_data;
525 0 : kmem_cache_free(mem, element);
526 0 : }
527 : EXPORT_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 : */
533 0 : void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
534 : {
535 0 : size_t size = (size_t)pool_data;
536 0 : return kmalloc(size, gfp_mask);
537 : }
538 : EXPORT_SYMBOL(mempool_kmalloc);
539 :
540 0 : void mempool_kfree(void *element, void *pool_data)
541 : {
542 0 : kfree(element);
543 0 : }
544 : EXPORT_SYMBOL(mempool_kfree);
545 :
546 : /*
547 : * A simple mempool-backed page allocator that allocates pages
548 : * of the order specified by pool_data.
549 : */
550 0 : void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
551 : {
552 0 : int order = (int)(long)pool_data;
553 0 : return alloc_pages(gfp_mask, order);
554 : }
555 : EXPORT_SYMBOL(mempool_alloc_pages);
556 :
557 0 : void mempool_free_pages(void *element, void *pool_data)
558 : {
559 0 : int order = (int)(long)pool_data;
560 0 : __free_pages(element, order);
561 0 : }
562 : EXPORT_SYMBOL(mempool_free_pages);
|
