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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) | |
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 | ||
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 | ||
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_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 */ | |
98 | static inline void check_element(mempool_t *pool, void *element) | |
99 | { | |
100 | } | |
101 | static inline void poison_element(mempool_t *pool, void *element) | |
102 | { | |
103 | } | |
104 | #endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */ | |
105 | ||
106 | static 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); | |
110 | if (pool->alloc == mempool_alloc_pages) | |
111 | kasan_free_pages(element, (unsigned long)pool->pool_data); | |
112 | } | |
113 | ||
114 | static 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 | ||
122 | static 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 | ||
130 | static 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 | */ | |
148 | void 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 | } | |
160 | EXPORT_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 | */ | |
176 | mempool_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 | } | |
182 | EXPORT_SYMBOL(mempool_create); | |
183 | ||
184 | mempool_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 | } | |
220 | EXPORT_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 | */ | |
238 | int 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 | } | |
293 | out_unlock: | |
294 | spin_unlock_irqrestore(&pool->lock, flags); | |
295 | out: | |
296 | return 0; | |
297 | } | |
298 | EXPORT_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 | */ | |
312 | void *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 | ||
328 | repeat_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 | } | |
379 | EXPORT_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 | */ | |
389 | void 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 | } | |
441 | EXPORT_SYMBOL(mempool_free); | |
442 | ||
443 | /* | |
444 | * A commonly used alloc and free fn. | |
445 | */ | |
446 | void *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 | } | |
452 | EXPORT_SYMBOL(mempool_alloc_slab); | |
453 | ||
454 | void mempool_free_slab(void *element, void *pool_data) | |
455 | { | |
456 | struct kmem_cache *mem = pool_data; | |
457 | kmem_cache_free(mem, element); | |
458 | } | |
459 | EXPORT_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 | */ | |
465 | void *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 | } | |
470 | EXPORT_SYMBOL(mempool_kmalloc); | |
471 | ||
472 | void mempool_kfree(void *element, void *pool_data) | |
473 | { | |
474 | kfree(element); | |
475 | } | |
476 | EXPORT_SYMBOL(mempool_kfree); | |
477 | ||
478 | /* | |
479 | * A simple mempool-backed page allocator that allocates pages | |
480 | * of the order specified by pool_data. | |
481 | */ | |
482 | void *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 | } | |
487 | EXPORT_SYMBOL(mempool_alloc_pages); | |
488 | ||
489 | void mempool_free_pages(void *element, void *pool_data) | |
490 | { | |
491 | int order = (int)(long)pool_data; | |
492 | __free_pages(element, order); | |
493 | } | |
494 | EXPORT_SYMBOL(mempool_free_pages); |