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1da177e4 LT |
1 | /* |
2 | * linux/mm/swap.c | |
3 | * | |
4 | * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds | |
5 | */ | |
6 | ||
7 | /* | |
8 | * This file contains the default values for the opereation of the | |
9 | * Linux VM subsystem. Fine-tuning documentation can be found in | |
10 | * Documentation/sysctl/vm.txt. | |
11 | * Started 18.12.91 | |
12 | * Swap aging added 23.2.95, Stephen Tweedie. | |
13 | * Buffermem limits added 12.3.98, Rik van Riel. | |
14 | */ | |
15 | ||
16 | #include <linux/mm.h> | |
17 | #include <linux/sched.h> | |
18 | #include <linux/kernel_stat.h> | |
19 | #include <linux/swap.h> | |
20 | #include <linux/mman.h> | |
21 | #include <linux/pagemap.h> | |
22 | #include <linux/pagevec.h> | |
23 | #include <linux/init.h> | |
24 | #include <linux/module.h> | |
25 | #include <linux/mm_inline.h> | |
26 | #include <linux/buffer_head.h> /* for try_to_release_page() */ | |
1da177e4 LT |
27 | #include <linux/percpu_counter.h> |
28 | #include <linux/percpu.h> | |
29 | #include <linux/cpu.h> | |
30 | #include <linux/notifier.h> | |
1da177e4 LT |
31 | |
32 | /* How many pages do we try to swap or page in/out together? */ | |
33 | int page_cluster; | |
34 | ||
902aaed0 HH |
35 | static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, }; |
36 | static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, }; | |
37 | static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs) = { 0, }; | |
38 | ||
b221385b AB |
39 | /* |
40 | * This path almost never happens for VM activity - pages are normally | |
41 | * freed via pagevecs. But it gets used by networking. | |
42 | */ | |
43 | static void fastcall __page_cache_release(struct page *page) | |
44 | { | |
45 | if (PageLRU(page)) { | |
46 | unsigned long flags; | |
47 | struct zone *zone = page_zone(page); | |
48 | ||
49 | spin_lock_irqsave(&zone->lru_lock, flags); | |
50 | VM_BUG_ON(!PageLRU(page)); | |
51 | __ClearPageLRU(page); | |
52 | del_page_from_lru(zone, page); | |
53 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
54 | } | |
55 | free_hot_page(page); | |
56 | } | |
57 | ||
8519fb30 | 58 | static void put_compound_page(struct page *page) |
1da177e4 | 59 | { |
d85f3385 | 60 | page = compound_head(page); |
8519fb30 | 61 | if (put_page_testzero(page)) { |
33f2ef89 | 62 | compound_page_dtor *dtor; |
1da177e4 | 63 | |
33f2ef89 | 64 | dtor = get_compound_page_dtor(page); |
8519fb30 | 65 | (*dtor)(page); |
1da177e4 | 66 | } |
8519fb30 NP |
67 | } |
68 | ||
69 | void put_page(struct page *page) | |
70 | { | |
71 | if (unlikely(PageCompound(page))) | |
72 | put_compound_page(page); | |
73 | else if (put_page_testzero(page)) | |
1da177e4 LT |
74 | __page_cache_release(page); |
75 | } | |
76 | EXPORT_SYMBOL(put_page); | |
1da177e4 | 77 | |
1d7ea732 AZ |
78 | /** |
79 | * put_pages_list(): release a list of pages | |
80 | * | |
81 | * Release a list of pages which are strung together on page.lru. Currently | |
82 | * used by read_cache_pages() and related error recovery code. | |
83 | * | |
84 | * @pages: list of pages threaded on page->lru | |
85 | */ | |
86 | void put_pages_list(struct list_head *pages) | |
87 | { | |
88 | while (!list_empty(pages)) { | |
89 | struct page *victim; | |
90 | ||
91 | victim = list_entry(pages->prev, struct page, lru); | |
92 | list_del(&victim->lru); | |
93 | page_cache_release(victim); | |
94 | } | |
95 | } | |
96 | EXPORT_SYMBOL(put_pages_list); | |
97 | ||
902aaed0 HH |
98 | /* |
99 | * pagevec_move_tail() must be called with IRQ disabled. | |
100 | * Otherwise this may cause nasty races. | |
101 | */ | |
102 | static void pagevec_move_tail(struct pagevec *pvec) | |
103 | { | |
104 | int i; | |
105 | int pgmoved = 0; | |
106 | struct zone *zone = NULL; | |
107 | ||
108 | for (i = 0; i < pagevec_count(pvec); i++) { | |
109 | struct page *page = pvec->pages[i]; | |
110 | struct zone *pagezone = page_zone(page); | |
111 | ||
112 | if (pagezone != zone) { | |
113 | if (zone) | |
114 | spin_unlock(&zone->lru_lock); | |
115 | zone = pagezone; | |
116 | spin_lock(&zone->lru_lock); | |
117 | } | |
118 | if (PageLRU(page) && !PageActive(page)) { | |
119 | list_move_tail(&page->lru, &zone->inactive_list); | |
120 | pgmoved++; | |
121 | } | |
122 | } | |
123 | if (zone) | |
124 | spin_unlock(&zone->lru_lock); | |
125 | __count_vm_events(PGROTATED, pgmoved); | |
126 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
127 | pagevec_reinit(pvec); | |
128 | } | |
129 | ||
1da177e4 LT |
130 | /* |
131 | * Writeback is about to end against a page which has been marked for immediate | |
132 | * reclaim. If it still appears to be reclaimable, move it to the tail of the | |
902aaed0 | 133 | * inactive list. |
1da177e4 LT |
134 | * |
135 | * Returns zero if it cleared PG_writeback. | |
136 | */ | |
137 | int rotate_reclaimable_page(struct page *page) | |
138 | { | |
902aaed0 | 139 | struct pagevec *pvec; |
1da177e4 LT |
140 | unsigned long flags; |
141 | ||
142 | if (PageLocked(page)) | |
143 | return 1; | |
144 | if (PageDirty(page)) | |
145 | return 1; | |
146 | if (PageActive(page)) | |
147 | return 1; | |
148 | if (!PageLRU(page)) | |
149 | return 1; | |
150 | ||
902aaed0 HH |
151 | page_cache_get(page); |
152 | local_irq_save(flags); | |
153 | pvec = &__get_cpu_var(lru_rotate_pvecs); | |
154 | if (!pagevec_add(pvec, page)) | |
155 | pagevec_move_tail(pvec); | |
156 | local_irq_restore(flags); | |
157 | ||
1da177e4 LT |
158 | if (!test_clear_page_writeback(page)) |
159 | BUG(); | |
902aaed0 | 160 | |
1da177e4 LT |
161 | return 0; |
162 | } | |
163 | ||
164 | /* | |
165 | * FIXME: speed this up? | |
166 | */ | |
167 | void fastcall activate_page(struct page *page) | |
168 | { | |
169 | struct zone *zone = page_zone(page); | |
170 | ||
171 | spin_lock_irq(&zone->lru_lock); | |
172 | if (PageLRU(page) && !PageActive(page)) { | |
173 | del_page_from_inactive_list(zone, page); | |
174 | SetPageActive(page); | |
175 | add_page_to_active_list(zone, page); | |
f8891e5e | 176 | __count_vm_event(PGACTIVATE); |
1da177e4 LT |
177 | } |
178 | spin_unlock_irq(&zone->lru_lock); | |
179 | } | |
180 | ||
181 | /* | |
182 | * Mark a page as having seen activity. | |
183 | * | |
184 | * inactive,unreferenced -> inactive,referenced | |
185 | * inactive,referenced -> active,unreferenced | |
186 | * active,unreferenced -> active,referenced | |
187 | */ | |
188 | void fastcall mark_page_accessed(struct page *page) | |
189 | { | |
190 | if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) { | |
191 | activate_page(page); | |
192 | ClearPageReferenced(page); | |
193 | } else if (!PageReferenced(page)) { | |
194 | SetPageReferenced(page); | |
195 | } | |
196 | } | |
197 | ||
198 | EXPORT_SYMBOL(mark_page_accessed); | |
199 | ||
200 | /** | |
201 | * lru_cache_add: add a page to the page lists | |
202 | * @page: the page to add | |
203 | */ | |
1da177e4 LT |
204 | void fastcall lru_cache_add(struct page *page) |
205 | { | |
206 | struct pagevec *pvec = &get_cpu_var(lru_add_pvecs); | |
207 | ||
208 | page_cache_get(page); | |
209 | if (!pagevec_add(pvec, page)) | |
210 | __pagevec_lru_add(pvec); | |
211 | put_cpu_var(lru_add_pvecs); | |
212 | } | |
213 | ||
214 | void fastcall lru_cache_add_active(struct page *page) | |
215 | { | |
216 | struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs); | |
217 | ||
218 | page_cache_get(page); | |
219 | if (!pagevec_add(pvec, page)) | |
220 | __pagevec_lru_add_active(pvec); | |
221 | put_cpu_var(lru_add_active_pvecs); | |
222 | } | |
223 | ||
902aaed0 HH |
224 | /* |
225 | * Drain pages out of the cpu's pagevecs. | |
226 | * Either "cpu" is the current CPU, and preemption has already been | |
227 | * disabled; or "cpu" is being hot-unplugged, and is already dead. | |
228 | */ | |
229 | static void drain_cpu_pagevecs(int cpu) | |
1da177e4 | 230 | { |
902aaed0 | 231 | struct pagevec *pvec; |
1da177e4 | 232 | |
902aaed0 | 233 | pvec = &per_cpu(lru_add_pvecs, cpu); |
1da177e4 LT |
234 | if (pagevec_count(pvec)) |
235 | __pagevec_lru_add(pvec); | |
902aaed0 | 236 | |
80bfed90 | 237 | pvec = &per_cpu(lru_add_active_pvecs, cpu); |
1da177e4 LT |
238 | if (pagevec_count(pvec)) |
239 | __pagevec_lru_add_active(pvec); | |
902aaed0 HH |
240 | |
241 | pvec = &per_cpu(lru_rotate_pvecs, cpu); | |
242 | if (pagevec_count(pvec)) { | |
243 | unsigned long flags; | |
244 | ||
245 | /* No harm done if a racing interrupt already did this */ | |
246 | local_irq_save(flags); | |
247 | pagevec_move_tail(pvec); | |
248 | local_irq_restore(flags); | |
249 | } | |
80bfed90 AM |
250 | } |
251 | ||
252 | void lru_add_drain(void) | |
253 | { | |
902aaed0 | 254 | drain_cpu_pagevecs(get_cpu()); |
80bfed90 | 255 | put_cpu(); |
1da177e4 LT |
256 | } |
257 | ||
053837fc | 258 | #ifdef CONFIG_NUMA |
c4028958 | 259 | static void lru_add_drain_per_cpu(struct work_struct *dummy) |
053837fc NP |
260 | { |
261 | lru_add_drain(); | |
262 | } | |
263 | ||
264 | /* | |
265 | * Returns 0 for success | |
266 | */ | |
267 | int lru_add_drain_all(void) | |
268 | { | |
c4028958 | 269 | return schedule_on_each_cpu(lru_add_drain_per_cpu); |
053837fc NP |
270 | } |
271 | ||
272 | #else | |
273 | ||
274 | /* | |
275 | * Returns 0 for success | |
276 | */ | |
277 | int lru_add_drain_all(void) | |
278 | { | |
279 | lru_add_drain(); | |
280 | return 0; | |
281 | } | |
282 | #endif | |
283 | ||
1da177e4 LT |
284 | /* |
285 | * Batched page_cache_release(). Decrement the reference count on all the | |
286 | * passed pages. If it fell to zero then remove the page from the LRU and | |
287 | * free it. | |
288 | * | |
289 | * Avoid taking zone->lru_lock if possible, but if it is taken, retain it | |
290 | * for the remainder of the operation. | |
291 | * | |
292 | * The locking in this function is against shrink_cache(): we recheck the | |
293 | * page count inside the lock to see whether shrink_cache grabbed the page | |
294 | * via the LRU. If it did, give up: shrink_cache will free it. | |
295 | */ | |
296 | void release_pages(struct page **pages, int nr, int cold) | |
297 | { | |
298 | int i; | |
299 | struct pagevec pages_to_free; | |
300 | struct zone *zone = NULL; | |
902aaed0 | 301 | unsigned long uninitialized_var(flags); |
1da177e4 LT |
302 | |
303 | pagevec_init(&pages_to_free, cold); | |
304 | for (i = 0; i < nr; i++) { | |
305 | struct page *page = pages[i]; | |
1da177e4 | 306 | |
8519fb30 NP |
307 | if (unlikely(PageCompound(page))) { |
308 | if (zone) { | |
902aaed0 | 309 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
8519fb30 NP |
310 | zone = NULL; |
311 | } | |
312 | put_compound_page(page); | |
313 | continue; | |
314 | } | |
315 | ||
b5810039 | 316 | if (!put_page_testzero(page)) |
1da177e4 LT |
317 | continue; |
318 | ||
46453a6e NP |
319 | if (PageLRU(page)) { |
320 | struct zone *pagezone = page_zone(page); | |
321 | if (pagezone != zone) { | |
322 | if (zone) | |
902aaed0 HH |
323 | spin_unlock_irqrestore(&zone->lru_lock, |
324 | flags); | |
46453a6e | 325 | zone = pagezone; |
902aaed0 | 326 | spin_lock_irqsave(&zone->lru_lock, flags); |
46453a6e | 327 | } |
725d704e | 328 | VM_BUG_ON(!PageLRU(page)); |
67453911 | 329 | __ClearPageLRU(page); |
1da177e4 | 330 | del_page_from_lru(zone, page); |
46453a6e NP |
331 | } |
332 | ||
333 | if (!pagevec_add(&pages_to_free, page)) { | |
334 | if (zone) { | |
902aaed0 | 335 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
46453a6e | 336 | zone = NULL; |
1da177e4 | 337 | } |
46453a6e NP |
338 | __pagevec_free(&pages_to_free); |
339 | pagevec_reinit(&pages_to_free); | |
340 | } | |
1da177e4 LT |
341 | } |
342 | if (zone) | |
902aaed0 | 343 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
1da177e4 LT |
344 | |
345 | pagevec_free(&pages_to_free); | |
346 | } | |
347 | ||
348 | /* | |
349 | * The pages which we're about to release may be in the deferred lru-addition | |
350 | * queues. That would prevent them from really being freed right now. That's | |
351 | * OK from a correctness point of view but is inefficient - those pages may be | |
352 | * cache-warm and we want to give them back to the page allocator ASAP. | |
353 | * | |
354 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() | |
355 | * and __pagevec_lru_add_active() call release_pages() directly to avoid | |
356 | * mutual recursion. | |
357 | */ | |
358 | void __pagevec_release(struct pagevec *pvec) | |
359 | { | |
360 | lru_add_drain(); | |
361 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); | |
362 | pagevec_reinit(pvec); | |
363 | } | |
364 | ||
7f285701 SF |
365 | EXPORT_SYMBOL(__pagevec_release); |
366 | ||
1da177e4 LT |
367 | /* |
368 | * pagevec_release() for pages which are known to not be on the LRU | |
369 | * | |
370 | * This function reinitialises the caller's pagevec. | |
371 | */ | |
372 | void __pagevec_release_nonlru(struct pagevec *pvec) | |
373 | { | |
374 | int i; | |
375 | struct pagevec pages_to_free; | |
376 | ||
377 | pagevec_init(&pages_to_free, pvec->cold); | |
1da177e4 LT |
378 | for (i = 0; i < pagevec_count(pvec); i++) { |
379 | struct page *page = pvec->pages[i]; | |
380 | ||
725d704e | 381 | VM_BUG_ON(PageLRU(page)); |
1da177e4 LT |
382 | if (put_page_testzero(page)) |
383 | pagevec_add(&pages_to_free, page); | |
384 | } | |
385 | pagevec_free(&pages_to_free); | |
386 | pagevec_reinit(pvec); | |
387 | } | |
388 | ||
389 | /* | |
390 | * Add the passed pages to the LRU, then drop the caller's refcount | |
391 | * on them. Reinitialises the caller's pagevec. | |
392 | */ | |
393 | void __pagevec_lru_add(struct pagevec *pvec) | |
394 | { | |
395 | int i; | |
396 | struct zone *zone = NULL; | |
397 | ||
398 | for (i = 0; i < pagevec_count(pvec); i++) { | |
399 | struct page *page = pvec->pages[i]; | |
400 | struct zone *pagezone = page_zone(page); | |
401 | ||
402 | if (pagezone != zone) { | |
403 | if (zone) | |
404 | spin_unlock_irq(&zone->lru_lock); | |
405 | zone = pagezone; | |
406 | spin_lock_irq(&zone->lru_lock); | |
407 | } | |
725d704e | 408 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 409 | SetPageLRU(page); |
1da177e4 LT |
410 | add_page_to_inactive_list(zone, page); |
411 | } | |
412 | if (zone) | |
413 | spin_unlock_irq(&zone->lru_lock); | |
414 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
415 | pagevec_reinit(pvec); | |
416 | } | |
417 | ||
418 | EXPORT_SYMBOL(__pagevec_lru_add); | |
419 | ||
420 | void __pagevec_lru_add_active(struct pagevec *pvec) | |
421 | { | |
422 | int i; | |
423 | struct zone *zone = NULL; | |
424 | ||
425 | for (i = 0; i < pagevec_count(pvec); i++) { | |
426 | struct page *page = pvec->pages[i]; | |
427 | struct zone *pagezone = page_zone(page); | |
428 | ||
429 | if (pagezone != zone) { | |
430 | if (zone) | |
431 | spin_unlock_irq(&zone->lru_lock); | |
432 | zone = pagezone; | |
433 | spin_lock_irq(&zone->lru_lock); | |
434 | } | |
725d704e | 435 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 436 | SetPageLRU(page); |
725d704e | 437 | VM_BUG_ON(PageActive(page)); |
4c84cacf | 438 | SetPageActive(page); |
1da177e4 LT |
439 | add_page_to_active_list(zone, page); |
440 | } | |
441 | if (zone) | |
442 | spin_unlock_irq(&zone->lru_lock); | |
443 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
444 | pagevec_reinit(pvec); | |
445 | } | |
446 | ||
447 | /* | |
448 | * Try to drop buffers from the pages in a pagevec | |
449 | */ | |
450 | void pagevec_strip(struct pagevec *pvec) | |
451 | { | |
452 | int i; | |
453 | ||
454 | for (i = 0; i < pagevec_count(pvec); i++) { | |
455 | struct page *page = pvec->pages[i]; | |
456 | ||
457 | if (PagePrivate(page) && !TestSetPageLocked(page)) { | |
5b40dc78 CL |
458 | if (PagePrivate(page)) |
459 | try_to_release_page(page, 0); | |
1da177e4 LT |
460 | unlock_page(page); |
461 | } | |
462 | } | |
463 | } | |
464 | ||
465 | /** | |
466 | * pagevec_lookup - gang pagecache lookup | |
467 | * @pvec: Where the resulting pages are placed | |
468 | * @mapping: The address_space to search | |
469 | * @start: The starting page index | |
470 | * @nr_pages: The maximum number of pages | |
471 | * | |
472 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages | |
473 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a | |
474 | * reference against the pages in @pvec. | |
475 | * | |
476 | * The search returns a group of mapping-contiguous pages with ascending | |
477 | * indexes. There may be holes in the indices due to not-present pages. | |
478 | * | |
479 | * pagevec_lookup() returns the number of pages which were found. | |
480 | */ | |
481 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, | |
482 | pgoff_t start, unsigned nr_pages) | |
483 | { | |
484 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); | |
485 | return pagevec_count(pvec); | |
486 | } | |
487 | ||
78539fdf CH |
488 | EXPORT_SYMBOL(pagevec_lookup); |
489 | ||
1da177e4 LT |
490 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, |
491 | pgoff_t *index, int tag, unsigned nr_pages) | |
492 | { | |
493 | pvec->nr = find_get_pages_tag(mapping, index, tag, | |
494 | nr_pages, pvec->pages); | |
495 | return pagevec_count(pvec); | |
496 | } | |
497 | ||
7f285701 | 498 | EXPORT_SYMBOL(pagevec_lookup_tag); |
1da177e4 LT |
499 | |
500 | #ifdef CONFIG_SMP | |
501 | /* | |
502 | * We tolerate a little inaccuracy to avoid ping-ponging the counter between | |
503 | * CPUs | |
504 | */ | |
505 | #define ACCT_THRESHOLD max(16, NR_CPUS * 2) | |
506 | ||
507 | static DEFINE_PER_CPU(long, committed_space) = 0; | |
508 | ||
509 | void vm_acct_memory(long pages) | |
510 | { | |
511 | long *local; | |
512 | ||
513 | preempt_disable(); | |
514 | local = &__get_cpu_var(committed_space); | |
515 | *local += pages; | |
516 | if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) { | |
517 | atomic_add(*local, &vm_committed_space); | |
518 | *local = 0; | |
519 | } | |
520 | preempt_enable(); | |
521 | } | |
1da177e4 LT |
522 | |
523 | #ifdef CONFIG_HOTPLUG_CPU | |
1da177e4 LT |
524 | |
525 | /* Drop the CPU's cached committed space back into the central pool. */ | |
526 | static int cpu_swap_callback(struct notifier_block *nfb, | |
527 | unsigned long action, | |
528 | void *hcpu) | |
529 | { | |
530 | long *committed; | |
531 | ||
532 | committed = &per_cpu(committed_space, (long)hcpu); | |
8bb78442 | 533 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { |
1da177e4 LT |
534 | atomic_add(*committed, &vm_committed_space); |
535 | *committed = 0; | |
902aaed0 | 536 | drain_cpu_pagevecs((long)hcpu); |
1da177e4 LT |
537 | } |
538 | return NOTIFY_OK; | |
539 | } | |
540 | #endif /* CONFIG_HOTPLUG_CPU */ | |
541 | #endif /* CONFIG_SMP */ | |
542 | ||
1da177e4 LT |
543 | /* |
544 | * Perform any setup for the swap system | |
545 | */ | |
546 | void __init swap_setup(void) | |
547 | { | |
548 | unsigned long megs = num_physpages >> (20 - PAGE_SHIFT); | |
549 | ||
550 | /* Use a smaller cluster for small-memory machines */ | |
551 | if (megs < 16) | |
552 | page_cluster = 2; | |
553 | else | |
554 | page_cluster = 3; | |
555 | /* | |
556 | * Right now other parts of the system means that we | |
557 | * _really_ don't want to cluster much more | |
558 | */ | |
02316067 | 559 | #ifdef CONFIG_HOTPLUG_CPU |
1da177e4 | 560 | hotcpu_notifier(cpu_swap_callback, 0); |
02316067 | 561 | #endif |
1da177e4 | 562 | } |