blob: 47a659dedd44405a277190d3bf9b1655636573d5
1 | /* |
2 | * linux/mm/mempool.c |
3 | * |
4 | * memory buffer pool support. Such pools are mostly used |
5 | * for guaranteed, deadlock-free memory allocations during |
6 | * extreme VM load. |
7 | * |
8 | * started by Ingo Molnar, Copyright (C) 2001 |
9 | * debugging by David Rientjes, Copyright (C) 2015 |
10 | */ |
11 | |
12 | #include <linux/mm.h> |
13 | #include <linux/slab.h> |
14 | #include <linux/highmem.h> |
15 | #include <linux/kasan.h> |
16 | #include <linux/kmemleak.h> |
17 | #include <linux/export.h> |
18 | #include <linux/mempool.h> |
19 | #include <linux/blkdev.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_free_slab || pool->free == mempool_kfree) |
61 | __check_element(pool, element, ksize(element)); |
62 | |
63 | /* Mempools backed by page allocator */ |
64 | if (pool->free == mempool_free_pages) { |
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 | |
87 | /* Mempools backed by page allocator */ |
88 | if (pool->alloc == mempool_alloc_pages) { |
89 | int order = (int)(long)pool->pool_data; |
90 | void *addr = kmap_atomic((struct page *)element); |
91 | |
92 | __poison_element(addr, 1UL << (PAGE_SHIFT + order)); |
93 | kunmap_atomic(addr); |
94 | } |
95 | } |
96 | #else /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */ |
97 | static inline void check_element(mempool_t *pool, void *element) |
98 | { |
99 | } |
100 | static inline void poison_element(mempool_t *pool, void *element) |
101 | { |
102 | } |
103 | #endif /* CONFIG_DEBUG_SLAB || CONFIG_SLUB_DEBUG_ON */ |
104 | |
105 | static void kasan_poison_element(mempool_t *pool, void *element) |
106 | { |
107 | if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc) |
108 | kasan_poison_kfree(element); |
109 | if (pool->alloc == mempool_alloc_pages) |
110 | kasan_free_pages(element, (unsigned long)pool->pool_data); |
111 | } |
112 | |
113 | static void kasan_unpoison_element(mempool_t *pool, void *element, gfp_t flags) |
114 | { |
115 | if (pool->alloc == mempool_alloc_slab || pool->alloc == mempool_kmalloc) |
116 | kasan_unpoison_slab(element); |
117 | if (pool->alloc == mempool_alloc_pages) |
118 | kasan_alloc_pages(element, (unsigned long)pool->pool_data); |
119 | } |
120 | |
121 | static void add_element(mempool_t *pool, void *element) |
122 | { |
123 | BUG_ON(pool->curr_nr >= pool->min_nr); |
124 | poison_element(pool, element); |
125 | kasan_poison_element(pool, element); |
126 | pool->elements[pool->curr_nr++] = element; |
127 | } |
128 | |
129 | static void *remove_element(mempool_t *pool, gfp_t flags) |
130 | { |
131 | void *element = pool->elements[--pool->curr_nr]; |
132 | |
133 | BUG_ON(pool->curr_nr < 0); |
134 | kasan_unpoison_element(pool, element, flags); |
135 | check_element(pool, element); |
136 | return element; |
137 | } |
138 | |
139 | /** |
140 | * mempool_destroy - deallocate a memory pool |
141 | * @pool: pointer to the memory pool which was allocated via |
142 | * mempool_create(). |
143 | * |
144 | * Free all reserved elements in @pool and @pool itself. This function |
145 | * only sleeps if the free_fn() function sleeps. |
146 | */ |
147 | void mempool_destroy(mempool_t *pool) |
148 | { |
149 | if (unlikely(!pool)) |
150 | return; |
151 | |
152 | while (pool->curr_nr) { |
153 | void *element = remove_element(pool, GFP_KERNEL); |
154 | pool->free(element, pool->pool_data); |
155 | } |
156 | kfree(pool->elements); |
157 | kfree(pool); |
158 | } |
159 | EXPORT_SYMBOL(mempool_destroy); |
160 | |
161 | /** |
162 | * mempool_create - create a memory pool |
163 | * @min_nr: the minimum number of elements guaranteed to be |
164 | * allocated for this pool. |
165 | * @alloc_fn: user-defined element-allocation function. |
166 | * @free_fn: user-defined element-freeing function. |
167 | * @pool_data: optional private data available to the user-defined functions. |
168 | * |
169 | * this function creates and allocates a guaranteed size, preallocated |
170 | * memory pool. The pool can be used from the mempool_alloc() and mempool_free() |
171 | * functions. This function might sleep. Both the alloc_fn() and the free_fn() |
172 | * functions might sleep - as long as the mempool_alloc() function is not called |
173 | * from IRQ contexts. |
174 | */ |
175 | mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn, |
176 | mempool_free_t *free_fn, void *pool_data) |
177 | { |
178 | return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data, |
179 | GFP_KERNEL, NUMA_NO_NODE); |
180 | } |
181 | EXPORT_SYMBOL(mempool_create); |
182 | |
183 | mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn, |
184 | mempool_free_t *free_fn, void *pool_data, |
185 | gfp_t gfp_mask, int node_id) |
186 | { |
187 | mempool_t *pool; |
188 | pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id); |
189 | if (!pool) |
190 | return NULL; |
191 | pool->elements = kmalloc_node(min_nr * sizeof(void *), |
192 | gfp_mask, node_id); |
193 | if (!pool->elements) { |
194 | kfree(pool); |
195 | return NULL; |
196 | } |
197 | spin_lock_init(&pool->lock); |
198 | pool->min_nr = min_nr; |
199 | pool->pool_data = pool_data; |
200 | init_waitqueue_head(&pool->wait); |
201 | pool->alloc = alloc_fn; |
202 | pool->free = free_fn; |
203 | |
204 | /* |
205 | * First pre-allocate the guaranteed number of buffers. |
206 | */ |
207 | while (pool->curr_nr < pool->min_nr) { |
208 | void *element; |
209 | |
210 | element = pool->alloc(gfp_mask, pool->pool_data); |
211 | if (unlikely(!element)) { |
212 | mempool_destroy(pool); |
213 | return NULL; |
214 | } |
215 | add_element(pool, element); |
216 | } |
217 | return pool; |
218 | } |
219 | EXPORT_SYMBOL(mempool_create_node); |
220 | |
221 | /** |
222 | * mempool_resize - resize an existing memory pool |
223 | * @pool: pointer to the memory pool which was allocated via |
224 | * mempool_create(). |
225 | * @new_min_nr: the new minimum number of elements guaranteed to be |
226 | * allocated for this pool. |
227 | * |
228 | * This function shrinks/grows the pool. In the case of growing, |
229 | * it cannot be guaranteed that the pool will be grown to the new |
230 | * size immediately, but new mempool_free() calls will refill it. |
231 | * This function may sleep. |
232 | * |
233 | * Note, the caller must guarantee that no mempool_destroy is called |
234 | * while this function is running. mempool_alloc() & mempool_free() |
235 | * might be called (eg. from IRQ contexts) while this function executes. |
236 | */ |
237 | int mempool_resize(mempool_t *pool, int new_min_nr) |
238 | { |
239 | void *element; |
240 | void **new_elements; |
241 | unsigned long flags; |
242 | |
243 | BUG_ON(new_min_nr <= 0); |
244 | might_sleep(); |
245 | |
246 | spin_lock_irqsave(&pool->lock, flags); |
247 | if (new_min_nr <= pool->min_nr) { |
248 | while (new_min_nr < pool->curr_nr) { |
249 | element = remove_element(pool, GFP_KERNEL); |
250 | spin_unlock_irqrestore(&pool->lock, flags); |
251 | pool->free(element, pool->pool_data); |
252 | spin_lock_irqsave(&pool->lock, flags); |
253 | } |
254 | pool->min_nr = new_min_nr; |
255 | goto out_unlock; |
256 | } |
257 | spin_unlock_irqrestore(&pool->lock, flags); |
258 | |
259 | /* Grow the pool */ |
260 | new_elements = kmalloc_array(new_min_nr, sizeof(*new_elements), |
261 | GFP_KERNEL); |
262 | if (!new_elements) |
263 | return -ENOMEM; |
264 | |
265 | spin_lock_irqsave(&pool->lock, flags); |
266 | if (unlikely(new_min_nr <= pool->min_nr)) { |
267 | /* Raced, other resize will do our work */ |
268 | spin_unlock_irqrestore(&pool->lock, flags); |
269 | kfree(new_elements); |
270 | goto out; |
271 | } |
272 | memcpy(new_elements, pool->elements, |
273 | pool->curr_nr * sizeof(*new_elements)); |
274 | kfree(pool->elements); |
275 | pool->elements = new_elements; |
276 | pool->min_nr = new_min_nr; |
277 | |
278 | while (pool->curr_nr < pool->min_nr) { |
279 | spin_unlock_irqrestore(&pool->lock, flags); |
280 | element = pool->alloc(GFP_KERNEL, pool->pool_data); |
281 | if (!element) |
282 | goto out; |
283 | spin_lock_irqsave(&pool->lock, flags); |
284 | if (pool->curr_nr < pool->min_nr) { |
285 | add_element(pool, element); |
286 | } else { |
287 | spin_unlock_irqrestore(&pool->lock, flags); |
288 | pool->free(element, pool->pool_data); /* Raced */ |
289 | goto out; |
290 | } |
291 | } |
292 | out_unlock: |
293 | spin_unlock_irqrestore(&pool->lock, flags); |
294 | out: |
295 | return 0; |
296 | } |
297 | EXPORT_SYMBOL(mempool_resize); |
298 | |
299 | /** |
300 | * mempool_alloc - allocate an element from a specific memory pool |
301 | * @pool: pointer to the memory pool which was allocated via |
302 | * mempool_create(). |
303 | * @gfp_mask: the usual allocation bitmask. |
304 | * |
305 | * this function only sleeps if the alloc_fn() function sleeps or |
306 | * returns NULL. Note that due to preallocation, this function |
307 | * *never* fails when called from process contexts. (it might |
308 | * fail if called from an IRQ context.) |
309 | * Note: using __GFP_ZERO is not supported. |
310 | */ |
311 | void *mempool_alloc(mempool_t *pool, gfp_t gfp_mask) |
312 | { |
313 | void *element; |
314 | unsigned long flags; |
315 | wait_queue_t wait; |
316 | gfp_t gfp_temp; |
317 | |
318 | VM_WARN_ON_ONCE(gfp_mask & __GFP_ZERO); |
319 | might_sleep_if(gfp_mask & __GFP_DIRECT_RECLAIM); |
320 | |
321 | gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */ |
322 | gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */ |
323 | gfp_mask |= __GFP_NOWARN; /* failures are OK */ |
324 | |
325 | gfp_temp = gfp_mask & ~(__GFP_DIRECT_RECLAIM|__GFP_IO); |
326 | |
327 | repeat_alloc: |
328 | |
329 | element = pool->alloc(gfp_temp, pool->pool_data); |
330 | if (likely(element != NULL)) |
331 | return element; |
332 | |
333 | spin_lock_irqsave(&pool->lock, flags); |
334 | if (likely(pool->curr_nr)) { |
335 | element = remove_element(pool, gfp_temp); |
336 | spin_unlock_irqrestore(&pool->lock, flags); |
337 | /* paired with rmb in mempool_free(), read comment there */ |
338 | smp_wmb(); |
339 | /* |
340 | * Update the allocation stack trace as this is more useful |
341 | * for debugging. |
342 | */ |
343 | kmemleak_update_trace(element); |
344 | return element; |
345 | } |
346 | |
347 | /* |
348 | * We use gfp mask w/o direct reclaim or IO for the first round. If |
349 | * alloc failed with that and @pool was empty, retry immediately. |
350 | */ |
351 | if (gfp_temp != gfp_mask) { |
352 | spin_unlock_irqrestore(&pool->lock, flags); |
353 | gfp_temp = gfp_mask; |
354 | goto repeat_alloc; |
355 | } |
356 | |
357 | /* We must not sleep if !__GFP_DIRECT_RECLAIM */ |
358 | if (!(gfp_mask & __GFP_DIRECT_RECLAIM)) { |
359 | spin_unlock_irqrestore(&pool->lock, flags); |
360 | return NULL; |
361 | } |
362 | |
363 | /* Let's wait for someone else to return an element to @pool */ |
364 | init_wait(&wait); |
365 | prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE); |
366 | |
367 | spin_unlock_irqrestore(&pool->lock, flags); |
368 | |
369 | /* |
370 | * FIXME: this should be io_schedule(). The timeout is there as a |
371 | * workaround for some DM problems in 2.6.18. |
372 | */ |
373 | io_schedule_timeout(5*HZ); |
374 | |
375 | finish_wait(&pool->wait, &wait); |
376 | goto repeat_alloc; |
377 | } |
378 | EXPORT_SYMBOL(mempool_alloc); |
379 | |
380 | /** |
381 | * mempool_free - return an element to the pool. |
382 | * @element: pool element pointer. |
383 | * @pool: pointer to the memory pool which was allocated via |
384 | * mempool_create(). |
385 | * |
386 | * this function only sleeps if the free_fn() function sleeps. |
387 | */ |
388 | void mempool_free(void *element, mempool_t *pool) |
389 | { |
390 | unsigned long flags; |
391 | |
392 | if (unlikely(element == NULL)) |
393 | return; |
394 | |
395 | /* |
396 | * Paired with the wmb in mempool_alloc(). The preceding read is |
397 | * for @element and the following @pool->curr_nr. This ensures |
398 | * that the visible value of @pool->curr_nr is from after the |
399 | * allocation of @element. This is necessary for fringe cases |
400 | * where @element was passed to this task without going through |
401 | * barriers. |
402 | * |
403 | * For example, assume @p is %NULL at the beginning and one task |
404 | * performs "p = mempool_alloc(...);" while another task is doing |
405 | * "while (!p) cpu_relax(); mempool_free(p, ...);". This function |
406 | * may end up using curr_nr value which is from before allocation |
407 | * of @p without the following rmb. |
408 | */ |
409 | smp_rmb(); |
410 | |
411 | /* |
412 | * For correctness, we need a test which is guaranteed to trigger |
413 | * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr |
414 | * without locking achieves that and refilling as soon as possible |
415 | * is desirable. |
416 | * |
417 | * Because curr_nr visible here is always a value after the |
418 | * allocation of @element, any task which decremented curr_nr below |
419 | * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets |
420 | * incremented to min_nr afterwards. If curr_nr gets incremented |
421 | * to min_nr after the allocation of @element, the elements |
422 | * allocated after that are subject to the same guarantee. |
423 | * |
424 | * Waiters happen iff curr_nr is 0 and the above guarantee also |
425 | * ensures that there will be frees which return elements to the |
426 | * pool waking up the waiters. |
427 | */ |
428 | if (unlikely(pool->curr_nr < pool->min_nr)) { |
429 | spin_lock_irqsave(&pool->lock, flags); |
430 | if (likely(pool->curr_nr < pool->min_nr)) { |
431 | add_element(pool, element); |
432 | spin_unlock_irqrestore(&pool->lock, flags); |
433 | wake_up(&pool->wait); |
434 | return; |
435 | } |
436 | spin_unlock_irqrestore(&pool->lock, flags); |
437 | } |
438 | pool->free(element, pool->pool_data); |
439 | } |
440 | EXPORT_SYMBOL(mempool_free); |
441 | |
442 | /* |
443 | * A commonly used alloc and free fn. |
444 | */ |
445 | void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data) |
446 | { |
447 | struct kmem_cache *mem = pool_data; |
448 | VM_BUG_ON(mem->ctor); |
449 | return kmem_cache_alloc(mem, gfp_mask); |
450 | } |
451 | EXPORT_SYMBOL(mempool_alloc_slab); |
452 | |
453 | void mempool_free_slab(void *element, void *pool_data) |
454 | { |
455 | struct kmem_cache *mem = pool_data; |
456 | kmem_cache_free(mem, element); |
457 | } |
458 | EXPORT_SYMBOL(mempool_free_slab); |
459 | |
460 | /* |
461 | * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory |
462 | * specified by pool_data |
463 | */ |
464 | void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data) |
465 | { |
466 | size_t size = (size_t)pool_data; |
467 | return kmalloc(size, gfp_mask); |
468 | } |
469 | EXPORT_SYMBOL(mempool_kmalloc); |
470 | |
471 | void mempool_kfree(void *element, void *pool_data) |
472 | { |
473 | kfree(element); |
474 | } |
475 | EXPORT_SYMBOL(mempool_kfree); |
476 | |
477 | /* |
478 | * A simple mempool-backed page allocator that allocates pages |
479 | * of the order specified by pool_data. |
480 | */ |
481 | void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data) |
482 | { |
483 | int order = (int)(long)pool_data; |
484 | return alloc_pages(gfp_mask, order); |
485 | } |
486 | EXPORT_SYMBOL(mempool_alloc_pages); |
487 | |
488 | void mempool_free_pages(void *element, void *pool_data) |
489 | { |
490 | int order = (int)(long)pool_data; |
491 | __free_pages(element, order); |
492 | } |
493 | EXPORT_SYMBOL(mempool_free_pages); |
494 |