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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 */
10
11#include <linux/mm.h>
12#include <linux/slab.h>
13#include <linux/module.h>
14#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
30static void free_pool(mempool_t *pool)
31{
32 while (pool->curr_nr) {
33 void *element = remove_element(pool);
34 pool->free(element, pool->pool_data);
35 }
36 kfree(pool->elements);
37 kfree(pool);
38}
39
40/**
41 * mempool_create - create a memory pool
42 * @min_nr: the minimum number of elements guaranteed to be
43 * allocated for this pool.
44 * @alloc_fn: user-defined element-allocation function.
45 * @free_fn: user-defined element-freeing function.
46 * @pool_data: optional private data available to the user-defined functions.
47 *
48 * this function creates and allocates a guaranteed size, preallocated
49 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
50 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
51 * functions might sleep - as long as the mempool_alloc() function is not called
52 * from IRQ contexts.
53 */
54mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
55 mempool_free_t *free_fn, void *pool_data)
56{
57 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,-1);
58}
59EXPORT_SYMBOL(mempool_create);
60
61mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
62 mempool_free_t *free_fn, void *pool_data, int node_id)
63{
64 mempool_t *pool;
65 pool = kmalloc_node(sizeof(*pool), GFP_KERNEL | __GFP_ZERO, node_id);
66 if (!pool)
67 return NULL;
68 pool->elements = kmalloc_node(min_nr * sizeof(void *),
69 GFP_KERNEL, node_id);
70 if (!pool->elements) {
71 kfree(pool);
72 return NULL;
73 }
74 spin_lock_init(&pool->lock);
75 pool->min_nr = min_nr;
76 pool->pool_data = pool_data;
77 init_waitqueue_head(&pool->wait);
78 pool->alloc = alloc_fn;
79 pool->free = free_fn;
80
81 /*
82 * First pre-allocate the guaranteed number of buffers.
83 */
84 while (pool->curr_nr < pool->min_nr) {
85 void *element;
86
87 element = pool->alloc(GFP_KERNEL, pool->pool_data);
88 if (unlikely(!element)) {
89 free_pool(pool);
90 return NULL;
91 }
92 add_element(pool, element);
93 }
94 return pool;
95}
96EXPORT_SYMBOL(mempool_create_node);
97
98/**
99 * mempool_resize - resize an existing memory pool
100 * @pool: pointer to the memory pool which was allocated via
101 * mempool_create().
102 * @new_min_nr: the new minimum number of elements guaranteed to be
103 * allocated for this pool.
104 * @gfp_mask: the usual allocation bitmask.
105 *
106 * This function shrinks/grows the pool. In the case of growing,
107 * it cannot be guaranteed that the pool will be grown to the new
108 * size immediately, but new mempool_free() calls will refill it.
109 *
110 * Note, the caller must guarantee that no mempool_destroy is called
111 * while this function is running. mempool_alloc() & mempool_free()
112 * might be called (eg. from IRQ contexts) while this function executes.
113 */
114int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask)
115{
116 void *element;
117 void **new_elements;
118 unsigned long flags;
119
120 BUG_ON(new_min_nr <= 0);
121
122 spin_lock_irqsave(&pool->lock, flags);
123 if (new_min_nr <= pool->min_nr) {
124 while (new_min_nr < pool->curr_nr) {
125 element = remove_element(pool);
126 spin_unlock_irqrestore(&pool->lock, flags);
127 pool->free(element, pool->pool_data);
128 spin_lock_irqsave(&pool->lock, flags);
129 }
130 pool->min_nr = new_min_nr;
131 goto out_unlock;
132 }
133 spin_unlock_irqrestore(&pool->lock, flags);
134
135 /* Grow the pool */
136 new_elements = kmalloc(new_min_nr * sizeof(*new_elements), gfp_mask);
137 if (!new_elements)
138 return -ENOMEM;
139
140 spin_lock_irqsave(&pool->lock, flags);
141 if (unlikely(new_min_nr <= pool->min_nr)) {
142 /* Raced, other resize will do our work */
143 spin_unlock_irqrestore(&pool->lock, flags);
144 kfree(new_elements);
145 goto out;
146 }
147 memcpy(new_elements, pool->elements,
148 pool->curr_nr * sizeof(*new_elements));
149 kfree(pool->elements);
150 pool->elements = new_elements;
151 pool->min_nr = new_min_nr;
152
153 while (pool->curr_nr < pool->min_nr) {
154 spin_unlock_irqrestore(&pool->lock, flags);
155 element = pool->alloc(gfp_mask, pool->pool_data);
156 if (!element)
157 goto out;
158 spin_lock_irqsave(&pool->lock, flags);
159 if (pool->curr_nr < pool->min_nr) {
160 add_element(pool, element);
161 } else {
162 spin_unlock_irqrestore(&pool->lock, flags);
163 pool->free(element, pool->pool_data); /* Raced */
164 goto out;
165 }
166 }
167out_unlock:
168 spin_unlock_irqrestore(&pool->lock, flags);
169out:
170 return 0;
171}
172EXPORT_SYMBOL(mempool_resize);
173
174/**
175 * mempool_destroy - deallocate a memory pool
176 * @pool: pointer to the memory pool which was allocated via
177 * mempool_create().
178 *
179 * this function only sleeps if the free_fn() function sleeps. The caller
180 * has to guarantee that all elements have been returned to the pool (ie:
181 * freed) prior to calling mempool_destroy().
182 */
183void mempool_destroy(mempool_t *pool)
184{
185 /* Check for outstanding elements */
186 BUG_ON(pool->curr_nr != pool->min_nr);
187 free_pool(pool);
188}
189EXPORT_SYMBOL(mempool_destroy);
190
191/**
192 * mempool_alloc - allocate an element from a specific memory pool
193 * @pool: pointer to the memory pool which was allocated via
194 * mempool_create().
195 * @gfp_mask: the usual allocation bitmask.
196 *
197 * this function only sleeps if the alloc_fn() function sleeps or
198 * returns NULL. Note that due to preallocation, this function
199 * *never* fails when called from process contexts. (it might
200 * fail if called from an IRQ context.)
201 */
202void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
203{
204 void *element;
205 unsigned long flags;
206 wait_queue_t wait;
207 gfp_t gfp_temp;
208
209 might_sleep_if(gfp_mask & __GFP_WAIT);
210
211 gfp_mask |= __GFP_NOMEMALLOC; /* don't allocate emergency reserves */
212 gfp_mask |= __GFP_NORETRY; /* don't loop in __alloc_pages */
213 gfp_mask |= __GFP_NOWARN; /* failures are OK */
214
215 gfp_temp = gfp_mask & ~(__GFP_WAIT|__GFP_IO);
216
217repeat_alloc:
218
219 element = pool->alloc(gfp_temp, pool->pool_data);
220 if (likely(element != NULL))
221 return element;
222
223 spin_lock_irqsave(&pool->lock, flags);
224 if (likely(pool->curr_nr)) {
225 element = remove_element(pool);
226 spin_unlock_irqrestore(&pool->lock, flags);
227 return element;
228 }
229 spin_unlock_irqrestore(&pool->lock, flags);
230
231 /* We must not sleep in the GFP_ATOMIC case */
232 if (!(gfp_mask & __GFP_WAIT))
233 return NULL;
234
235 /* Now start performing page reclaim */
236 gfp_temp = gfp_mask;
237 init_wait(&wait);
238 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
239 smp_mb();
240 if (!pool->curr_nr) {
241 /*
242 * FIXME: this should be io_schedule(). The timeout is there
243 * as a workaround for some DM problems in 2.6.18.
244 */
245 io_schedule_timeout(5*HZ);
246 }
247 finish_wait(&pool->wait, &wait);
248
249 goto repeat_alloc;
250}
251EXPORT_SYMBOL(mempool_alloc);
252
253/**
254 * mempool_free - return an element to the pool.
255 * @element: pool element pointer.
256 * @pool: pointer to the memory pool which was allocated via
257 * mempool_create().
258 *
259 * this function only sleeps if the free_fn() function sleeps.
260 */
261void mempool_free(void *element, mempool_t *pool)
262{
263 unsigned long flags;
264
265 if (unlikely(element == NULL))
266 return;
267
268 smp_mb();
269 if (pool->curr_nr < pool->min_nr) {
270 spin_lock_irqsave(&pool->lock, flags);
271 if (pool->curr_nr < pool->min_nr) {
272 add_element(pool, element);
273 spin_unlock_irqrestore(&pool->lock, flags);
274 wake_up(&pool->wait);
275 return;
276 }
277 spin_unlock_irqrestore(&pool->lock, flags);
278 }
279 pool->free(element, pool->pool_data);
280}
281EXPORT_SYMBOL(mempool_free);
282
283/*
284 * A commonly used alloc and free fn.
285 */
286void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
287{
288 struct kmem_cache *mem = pool_data;
289 return kmem_cache_alloc(mem, gfp_mask);
290}
291EXPORT_SYMBOL(mempool_alloc_slab);
292
293void mempool_free_slab(void *element, void *pool_data)
294{
295 struct kmem_cache *mem = pool_data;
296 kmem_cache_free(mem, element);
297}
298EXPORT_SYMBOL(mempool_free_slab);
299
300/*
301 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
302 * specified by pool_data
303 */
304void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
305{
306 size_t size = (size_t)pool_data;
307 return kmalloc(size, gfp_mask);
308}
309EXPORT_SYMBOL(mempool_kmalloc);
310
311void mempool_kfree(void *element, void *pool_data)
312{
313 kfree(element);
314}
315EXPORT_SYMBOL(mempool_kfree);
316
317/*
318 * A simple mempool-backed page allocator that allocates pages
319 * of the order specified by pool_data.
320 */
321void *mempool_alloc_pages(gfp_t gfp_mask, void *pool_data)
322{
323 int order = (int)(long)pool_data;
324 return alloc_pages(gfp_mask, order);
325}
326EXPORT_SYMBOL(mempool_alloc_pages);
327
328void mempool_free_pages(void *element, void *pool_data)
329{
330 int order = (int)(long)pool_data;
331 __free_pages(element, order);
332}
333EXPORT_SYMBOL(mempool_free_pages);
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 */
10
11#include <linux/mm.h>
12#include <linux/slab.h>
13#include <linux/export.h>
14#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
30/**
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)
39{
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}
47EXPORT_SYMBOL(mempool_destroy);
48
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
58 * memory pool. The pool can be used from the mempool_alloc() and mempool_free()
59 * functions. This function might sleep. Both the alloc_fn() and the free_fn()
60 * functions might sleep - as long as the mempool_alloc() function is not called
61 * from IRQ contexts.
62 */
63mempool_t *mempool_create(int min_nr, mempool_alloc_t *alloc_fn,
64 mempool_free_t *free_fn, void *pool_data)
65{
66 return mempool_create_node(min_nr,alloc_fn,free_fn, pool_data,
67 GFP_KERNEL, NUMA_NO_NODE);
68}
69EXPORT_SYMBOL(mempool_create);
70
71mempool_t *mempool_create_node(int min_nr, mempool_alloc_t *alloc_fn,
72 mempool_free_t *free_fn, void *pool_data,
73 gfp_t gfp_mask, int node_id)
74{
75 mempool_t *pool;
76 pool = kzalloc_node(sizeof(*pool), gfp_mask, node_id);
77 if (!pool)
78 return NULL;
79 pool->elements = kmalloc_node(min_nr * sizeof(void *),
80 gfp_mask, node_id);
81 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
98 element = pool->alloc(gfp_mask, pool->pool_data);
99 if (unlikely(!element)) {
100 mempool_destroy(pool);
101 return NULL;
102 }
103 add_element(pool, element);
104 }
105 return pool;
106}
107EXPORT_SYMBOL(mempool_create_node);
108
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 */
125int mempool_resize(mempool_t *pool, int new_min_nr, gfp_t gfp_mask)
126{
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/**
186 * 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 *
191 * this function only sleeps if the alloc_fn() function sleeps or
192 * 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 */
196void * mempool_alloc(mempool_t *pool, gfp_t gfp_mask)
197{
198 void *element;
199 unsigned long flags;
200 wait_queue_t wait;
201 gfp_t gfp_temp;
202
203 might_sleep_if(gfp_mask & __GFP_WAIT);
204
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 */
208
209 gfp_temp = gfp_mask & ~(__GFP_WAIT|__GFP_IO);
210
211repeat_alloc:
212
213 element = pool->alloc(gfp_temp, pool->pool_data);
214 if (likely(element != NULL))
215 return element;
216
217 spin_lock_irqsave(&pool->lock, flags);
218 if (likely(pool->curr_nr)) {
219 element = remove_element(pool);
220 spin_unlock_irqrestore(&pool->lock, flags);
221 /* paired with rmb in mempool_free(), read comment there */
222 smp_wmb();
223 return element;
224 }
225
226 /*
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 */
237 if (!(gfp_mask & __GFP_WAIT)) {
238 spin_unlock_irqrestore(&pool->lock, flags);
239 return NULL;
240 }
241
242 /* Let's wait for someone else to return an element to @pool */
243 init_wait(&wait);
244 prepare_to_wait(&pool->wait, &wait, TASK_UNINTERRUPTIBLE);
245
246 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);
255 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
271 if (unlikely(element == NULL))
272 return;
273
274 /*
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 */
307 if (unlikely(pool->curr_nr < pool->min_nr)) {
308 spin_lock_irqsave(&pool->lock, flags);
309 if (likely(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 */
324void *mempool_alloc_slab(gfp_t gfp_mask, void *pool_data)
325{
326 struct kmem_cache *mem = pool_data;
327 return kmem_cache_alloc(mem, gfp_mask);
328}
329EXPORT_SYMBOL(mempool_alloc_slab);
330
331void mempool_free_slab(void *element, void *pool_data)
332{
333 struct kmem_cache *mem = pool_data;
334 kmem_cache_free(mem, element);
335}
336EXPORT_SYMBOL(mempool_free_slab);
337
338/*
339 * A commonly used alloc and free fn that kmalloc/kfrees the amount of memory
340 * specified by pool_data
341 */
342void *mempool_kmalloc(gfp_t gfp_mask, void *pool_data)
343{
344 size_t size = (size_t)pool_data;
345 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/*
356 * 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);