blob: 54990476c049b2fa60c5e740a0533ea70df1f856 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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 */
10
11#include <linux/mm.h>
12#include <linux/slab.h>
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040013#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070014#include <linux/mempool.h>
15#include <linux/blkdev.h>
16#include <linux/writeback.h>
17
18static void add_element(mempool_t *pool, void *element)
19{
20 BUG_ON(pool->curr_nr >= pool->min_nr);
21 pool->elements[pool->curr_nr++] = element;
22}
23
24static void *remove_element(mempool_t *pool)
25{
26 BUG_ON(pool->curr_nr <= 0);
27 return pool->elements[--pool->curr_nr];
28}
29
Tejun Heo0565d312012-01-10 15:08:26 -080030/**
31 * mempool_destroy - deallocate a memory pool
32 * @pool: pointer to the memory pool which was allocated via
33 * mempool_create().
34 *
35 * Free all reserved elements in @pool and @pool itself. This function
36 * only sleeps if the free_fn() function sleeps.
37 */
38void mempool_destroy(mempool_t *pool)
Linus Torvalds1da177e2005-04-16 15:20:36 -070039{
40 while (pool->curr_nr) {
41 void *element = remove_element(pool);
42 pool->free(element, pool->pool_data);
43 }
44 kfree(pool->elements);
45 kfree(pool);
46}
Tejun Heo0565d312012-01-10 15:08:26 -080047EXPORT_SYMBOL(mempool_destroy);
Linus Torvalds1da177e2005-04-16 15:20:36 -070048
49/**
50 * mempool_create - create a memory pool
51 * @min_nr: the minimum number of elements guaranteed to be
52 * allocated for this pool.
53 * @alloc_fn: user-defined element-allocation function.
54 * @free_fn: user-defined element-freeing function.
55 * @pool_data: optional private data available to the user-defined functions.
56 *
57 * this function creates and allocates a guaranteed size, preallocated
Robert P. J. Day72fd4a32007-02-10 01:45:59 -080058 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
Linus Torvalds1da177e2005-04-16 15:20:36 -070059 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
Robert P. J. Day72fd4a32007-02-10 01:45:59 -080060 * functions might sleep - as long as the mempool_alloc() function is not called
Linus Torvalds1da177e2005-04-16 15:20:36 -070061 * from IRQ contexts.
62 */
Christoph Lameter19460892005-06-23 00:08:19 -070063mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
Linus Torvalds1da177e2005-04-16 15:20:36 -070064 mempool_free_t *free_fn, void *pool_data)
65{
Tejun Heoa91a5ac2012-06-04 20:40:53 -070066 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,
67 GFP_KERNEL, NUMA_NO_NODE);
Christoph Lameter19460892005-06-23 00:08:19 -070068}
69EXPORT_SYMBOL(mempool_create);
Linus Torvalds1da177e2005-04-16 15:20:36 -070070
Christoph Lameter19460892005-06-23 00:08:19 -070071mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
Tejun Heoa91a5ac2012-06-04 20:40:53 -070072 mempool_free_t *free_fn, void *pool_data,
73 gfp_t gfp_mask, int node_id)
Christoph Lameter19460892005-06-23 00:08:19 -070074{
75 mempool_t *pool;
Tejun Heoa91a5ac2012-06-04 20:40:53 -070076 pool = kmalloc_node(sizeof(*pool), gfp_mask | __GFP_ZERO, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 if (!pool)
78 return NULL;
Christoph Lameter19460892005-06-23 00:08:19 -070079 pool->elements = kmalloc_node(min_nr * sizeof(void *),
Tejun Heoa91a5ac2012-06-04 20:40:53 -070080 gfp_mask, node_id);
Linus Torvalds1da177e2005-04-16 15:20:36 -070081 if (!pool->elements) {
82 kfree(pool);
83 return NULL;
84 }
85 spin_lock_init(&pool->lock);
86 pool->min_nr = min_nr;
87 pool->pool_data = pool_data;
88 init_waitqueue_head(&pool->wait);
89 pool->alloc = alloc_fn;
90 pool->free = free_fn;
91
92 /*
93 * First pre-allocate the guaranteed number of buffers.
94 */
95 while (pool->curr_nr < pool->min_nr) {
96 void *element;
97
Tejun Heoa91a5ac2012-06-04 20:40:53 -070098 element = pool->alloc(gfp_mask, pool->pool_data);
Linus Torvalds1da177e2005-04-16 15:20:36 -070099 if (unlikely(!element)) {
Tejun Heo0565d312012-01-10 15:08:26 -0800100 mempool_destroy(pool);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700101 return NULL;
102 }
103 add_element(pool, element);
104 }
105 return pool;
106}
Christoph Lameter19460892005-06-23 00:08:19 -0700107EXPORT_SYMBOL(mempool_create_node);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700108
109/**
110 * mempool_resize - resize an existing memory pool
111 * @pool: pointer to the memory pool which was allocated via
112 * mempool_create().
113 * @new_min_nr: the new minimum number of elements guaranteed to be
114 * allocated for this pool.
115 * @gfp_mask: the usual allocation bitmask.
116 *
117 * This function shrinks/grows the pool. In the case of growing,
118 * it cannot be guaranteed that the pool will be grown to the new
119 * size immediately, but new mempool_free() calls will refill it.
120 *
121 * Note, the caller must guarantee that no mempool_destroy is called
122 * while this function is running. mempool_alloc() & mempool_free()
123 * might be called (eg. from IRQ contexts) while this function executes.
124 */
Al Virodd0fc662005-10-07 07:46:04 +0100125int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700126{
127 void *element;
128 void **new_elements;
129 unsigned long flags;
130
131 BUG_ON(new_min_nr <= 0);
132
133 spin_lock_irqsave(&pool->lock, flags);
134 if (new_min_nr <= pool->min_nr) {
135 while (new_min_nr < pool->curr_nr) {
136 element = remove_element(pool);
137 spin_unlock_irqrestore(&pool->lock, flags);
138 pool->free(element, pool->pool_data);
139 spin_lock_irqsave(&pool->lock, flags);
140 }
141 pool->min_nr = new_min_nr;
142 goto out_unlock;
143 }
144 spin_unlock_irqrestore(&pool->lock, flags);
145
146 /* Grow the pool */
147 new_elements = kmalloc(new_min_nr * sizeof(*new_elements), gfp_mask);
148 if (!new_elements)
149 return -ENOMEM;
150
151 spin_lock_irqsave(&pool->lock, flags);
152 if (unlikely(new_min_nr <= pool->min_nr)) {
153 /* Raced, other resize will do our work */
154 spin_unlock_irqrestore(&pool->lock, flags);
155 kfree(new_elements);
156 goto out;
157 }
158 memcpy(new_elements, pool->elements,
159 pool->curr_nr * sizeof(*new_elements));
160 kfree(pool->elements);
161 pool->elements = new_elements;
162 pool->min_nr = new_min_nr;
163
164 while (pool->curr_nr < pool->min_nr) {
165 spin_unlock_irqrestore(&pool->lock, flags);
166 element = pool->alloc(gfp_mask, pool->pool_data);
167 if (!element)
168 goto out;
169 spin_lock_irqsave(&pool->lock, flags);
170 if (pool->curr_nr < pool->min_nr) {
171 add_element(pool, element);
172 } else {
173 spin_unlock_irqrestore(&pool->lock, flags);
174 pool->free(element, pool->pool_data); /* Raced */
175 goto out;
176 }
177 }
178out_unlock:
179 spin_unlock_irqrestore(&pool->lock, flags);
180out:
181 return 0;
182}
183EXPORT_SYMBOL(mempool_resize);
184
185/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700186 * mempool_alloc - allocate an element from a specific memory pool
187 * @pool: pointer to the memory pool which was allocated via
188 * mempool_create().
189 * @gfp_mask: the usual allocation bitmask.
190 *
Robert P. J. Day72fd4a32007-02-10 01:45:59 -0800191 * this function only sleeps if the alloc_fn() function sleeps or
Linus Torvalds1da177e2005-04-16 15:20:36 -0700192 * returns NULL. Note that due to preallocation, this function
193 * *never* fails when called from process contexts. (it might
194 * fail if called from an IRQ context.)
195 */
Al Virodd0fc662005-10-07 07:46:04 +0100196void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700197{
198 void *element;
199 unsigned long flags;
Benjamin LaHaise01890a42005-06-23 00:10:01 -0700200 wait_queue_t wait;
Al Viro6daa0e22005-10-21 03:18:50 -0400201 gfp_t gfp_temp;
Nick Piggin20a77772005-05-01 08:58:37 -0700202
203 might_sleep_if(gfp_mask & __GFP_WAIT);
Nick Pigginb84a35b2005-05-01 08:58:36 -0700204
205 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
206 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
207 gfp_mask |= __GFP_NOWARN; /* failures are OK */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208
Nick Piggin20a77772005-05-01 08:58:37 -0700209 gfp_temp = gfp_mask & ~(__GFP_WAIT|__GFP_IO);
210
Linus Torvalds1da177e2005-04-16 15:20:36 -0700211repeat_alloc:
Nick Piggin20a77772005-05-01 08:58:37 -0700212
213 element = pool->alloc(gfp_temp, pool->pool_data);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700214 if (likely(element != NULL))
215 return element;
216
Linus Torvalds1da177e2005-04-16 15:20:36 -0700217 spin_lock_irqsave(&pool->lock, flags);
218 if (likely(pool->curr_nr)) {
219 element = remove_element(pool);
220 spin_unlock_irqrestore(&pool->lock, flags);
Tejun Heo5b990542012-01-10 15:08:23 -0800221 /* paired with rmb in mempool_free(), read comment there */
222 smp_wmb();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700223 return element;
224 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700225
Tejun Heo1ebb7042012-01-10 15:08:28 -0800226 /*
227 * We use gfp mask w/o __GFP_WAIT or IO for the first round. If
228 * alloc failed with that and @pool was empty, retry immediately.
229 */
230 if (gfp_temp != gfp_mask) {
231 spin_unlock_irqrestore(&pool->lock, flags);
232 gfp_temp = gfp_mask;
233 goto repeat_alloc;
234 }
235
236 /* We must not sleep if !__GFP_WAIT */
Tejun Heo5b990542012-01-10 15:08:23 -0800237 if (!(gfp_mask & __GFP_WAIT)) {
238 spin_unlock_irqrestore(&pool->lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700239 return NULL;
Tejun Heo5b990542012-01-10 15:08:23 -0800240 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241
Tejun Heo5b990542012-01-10 15:08:23 -0800242 /* Let's wait for someone else to return an element to @pool */
Benjamin LaHaise01890a42005-06-23 00:10:01 -0700243 init_wait(&wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245
Tejun Heo5b990542012-01-10 15:08:23 -0800246 spin_unlock_irqrestore(&pool->lock, flags);
247
248 /*
249 * FIXME: this should be io_schedule(). The timeout is there as a
250 * workaround for some DM problems in 2.6.18.
251 */
252 io_schedule_timeout(5*HZ);
253
254 finish_wait(&pool->wait, &wait);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700255 goto repeat_alloc;
256}
257EXPORT_SYMBOL(mempool_alloc);
258
259/**
260 * mempool_free - return an element to the pool.
261 * @element: pool element pointer.
262 * @pool: pointer to the memory pool which was allocated via
263 * mempool_create().
264 *
265 * this function only sleeps if the free_fn() function sleeps.
266 */
267void mempool_free(void *element, mempool_t *pool)
268{
269 unsigned long flags;
270
Rusty Russellc80e7a82007-07-15 23:42:00 -0700271 if (unlikely(element == NULL))
272 return;
273
Tejun Heo5b990542012-01-10 15:08:23 -0800274 /*
275 * Paired with the wmb in mempool_alloc(). The preceding read is
276 * for @element and the following @pool->curr_nr. This ensures
277 * that the visible value of @pool->curr_nr is from after the
278 * allocation of @element. This is necessary for fringe cases
279 * where @element was passed to this task without going through
280 * barriers.
281 *
282 * For example, assume @p is %NULL at the beginning and one task
283 * performs "p = mempool_alloc(...);" while another task is doing
284 * "while (!p) cpu_relax(); mempool_free(p, ...);". This function
285 * may end up using curr_nr value which is from before allocation
286 * of @p without the following rmb.
287 */
288 smp_rmb();
289
290 /*
291 * For correctness, we need a test which is guaranteed to trigger
292 * if curr_nr + #allocated == min_nr. Testing curr_nr < min_nr
293 * without locking achieves that and refilling as soon as possible
294 * is desirable.
295 *
296 * Because curr_nr visible here is always a value after the
297 * allocation of @element, any task which decremented curr_nr below
298 * min_nr is guaranteed to see curr_nr < min_nr unless curr_nr gets
299 * incremented to min_nr afterwards. If curr_nr gets incremented
300 * to min_nr after the allocation of @element, the elements
301 * allocated after that are subject to the same guarantee.
302 *
303 * Waiters happen iff curr_nr is 0 and the above guarantee also
304 * ensures that there will be frees which return elements to the
305 * pool waking up the waiters.
306 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700307 if (pool->curr_nr < pool->min_nr) {
308 spin_lock_irqsave(&pool->lock, flags);
309 if (pool->curr_nr < pool->min_nr) {
310 add_element(pool, element);
311 spin_unlock_irqrestore(&pool->lock, flags);
312 wake_up(&pool->wait);
313 return;
314 }
315 spin_unlock_irqrestore(&pool->lock, flags);
316 }
317 pool->free(element, pool->pool_data);
318}
319EXPORT_SYMBOL(mempool_free);
320
321/*
322 * A commonly used alloc and free fn.
323 */
Al Virodd0fc662005-10-07 07:46:04 +0100324void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325{
Pekka Enbergfcc234f2006-03-22 00:08:13 -0800326 struct kmem_cache *mem = pool_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700327 return kmem_cache_alloc(mem, gfp_mask);
328}
329EXPORT_SYMBOL(mempool_alloc_slab);
330
331void mempool_free_slab(void *element, void *pool_data)
332{
Pekka Enbergfcc234f2006-03-22 00:08:13 -0800333 struct kmem_cache *mem = pool_data;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700334 kmem_cache_free(mem, element);
335}
336EXPORT_SYMBOL(mempool_free_slab);
Matthew Dobson6e0678f2006-03-26 01:37:44 -0800337
338/*
Matthew Dobson53184082006-03-26 01:37:46 -0800339 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
Simon Arlott183ff222007-10-20 01:27:18 +0200340 * specified by pool_data
Matthew Dobson53184082006-03-26 01:37:46 -0800341 */
342void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
343{
Figo.zhang5e2f89b2009-08-08 21:01:22 +0800344 size_t size = (size_t)pool_data;
Matthew Dobson53184082006-03-26 01:37:46 -0800345 return kmalloc(size, gfp_mask);
346}
347EXPORT_SYMBOL(mempool_kmalloc);
348
349void mempool_kfree(void *element, void *pool_data)
350{
351 kfree(element);
352}
353EXPORT_SYMBOL(mempool_kfree);
354
355/*
Matthew Dobson6e0678f2006-03-26 01:37:44 -0800356 * A simple mempool-backed page allocator that allocates pages
357 * of the order specified by pool_data.
358 */
359void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
360{
361 int order = (int)(long)pool_data;
362 return alloc_pages(gfp_mask, order);
363}
364EXPORT_SYMBOL(mempool_alloc_pages);
365
366void mempool_free_pages(void *element, void *pool_data)
367{
368 int order = (int)(long)pool_data;
369 __free_pages(element, order);
370}
371EXPORT_SYMBOL(mempool_free_pages);