Commit | Line | Data |
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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() */ | |
27 | #include <linux/module.h> | |
28 | #include <linux/percpu_counter.h> | |
29 | #include <linux/percpu.h> | |
30 | #include <linux/cpu.h> | |
31 | #include <linux/notifier.h> | |
32 | #include <linux/init.h> | |
33 | ||
34 | /* How many pages do we try to swap or page in/out together? */ | |
35 | int page_cluster; | |
36 | ||
8519fb30 | 37 | static void put_compound_page(struct page *page) |
1da177e4 | 38 | { |
8519fb30 NP |
39 | page = (struct page *)page_private(page); |
40 | if (put_page_testzero(page)) { | |
41 | void (*dtor)(struct page *page); | |
1da177e4 | 42 | |
41d78ba5 | 43 | dtor = (void (*)(struct page *))page[1].lru.next; |
8519fb30 | 44 | (*dtor)(page); |
1da177e4 | 45 | } |
8519fb30 NP |
46 | } |
47 | ||
48 | void put_page(struct page *page) | |
49 | { | |
50 | if (unlikely(PageCompound(page))) | |
51 | put_compound_page(page); | |
52 | else if (put_page_testzero(page)) | |
1da177e4 LT |
53 | __page_cache_release(page); |
54 | } | |
55 | EXPORT_SYMBOL(put_page); | |
1da177e4 | 56 | |
1d7ea732 AZ |
57 | /** |
58 | * put_pages_list(): release a list of pages | |
59 | * | |
60 | * Release a list of pages which are strung together on page.lru. Currently | |
61 | * used by read_cache_pages() and related error recovery code. | |
62 | * | |
63 | * @pages: list of pages threaded on page->lru | |
64 | */ | |
65 | void put_pages_list(struct list_head *pages) | |
66 | { | |
67 | while (!list_empty(pages)) { | |
68 | struct page *victim; | |
69 | ||
70 | victim = list_entry(pages->prev, struct page, lru); | |
71 | list_del(&victim->lru); | |
72 | page_cache_release(victim); | |
73 | } | |
74 | } | |
75 | EXPORT_SYMBOL(put_pages_list); | |
76 | ||
1da177e4 LT |
77 | /* |
78 | * Writeback is about to end against a page which has been marked for immediate | |
79 | * reclaim. If it still appears to be reclaimable, move it to the tail of the | |
80 | * inactive list. The page still has PageWriteback set, which will pin it. | |
81 | * | |
82 | * We don't expect many pages to come through here, so don't bother batching | |
83 | * things up. | |
84 | * | |
85 | * To avoid placing the page at the tail of the LRU while PG_writeback is still | |
86 | * set, this function will clear PG_writeback before performing the page | |
87 | * motion. Do that inside the lru lock because once PG_writeback is cleared | |
88 | * we may not touch the page. | |
89 | * | |
90 | * Returns zero if it cleared PG_writeback. | |
91 | */ | |
92 | int rotate_reclaimable_page(struct page *page) | |
93 | { | |
94 | struct zone *zone; | |
95 | unsigned long flags; | |
96 | ||
97 | if (PageLocked(page)) | |
98 | return 1; | |
99 | if (PageDirty(page)) | |
100 | return 1; | |
101 | if (PageActive(page)) | |
102 | return 1; | |
103 | if (!PageLRU(page)) | |
104 | return 1; | |
105 | ||
106 | zone = page_zone(page); | |
107 | spin_lock_irqsave(&zone->lru_lock, flags); | |
108 | if (PageLRU(page) && !PageActive(page)) { | |
1bfba4e8 | 109 | list_move_tail(&page->lru, &zone->inactive_list); |
f8891e5e | 110 | __count_vm_event(PGROTATED); |
1da177e4 LT |
111 | } |
112 | if (!test_clear_page_writeback(page)) | |
113 | BUG(); | |
114 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
115 | return 0; | |
116 | } | |
117 | ||
118 | /* | |
119 | * FIXME: speed this up? | |
120 | */ | |
121 | void fastcall activate_page(struct page *page) | |
122 | { | |
123 | struct zone *zone = page_zone(page); | |
124 | ||
125 | spin_lock_irq(&zone->lru_lock); | |
126 | if (PageLRU(page) && !PageActive(page)) { | |
127 | del_page_from_inactive_list(zone, page); | |
128 | SetPageActive(page); | |
129 | add_page_to_active_list(zone, page); | |
f8891e5e | 130 | __count_vm_event(PGACTIVATE); |
1da177e4 LT |
131 | } |
132 | spin_unlock_irq(&zone->lru_lock); | |
133 | } | |
134 | ||
135 | /* | |
136 | * Mark a page as having seen activity. | |
137 | * | |
138 | * inactive,unreferenced -> inactive,referenced | |
139 | * inactive,referenced -> active,unreferenced | |
140 | * active,unreferenced -> active,referenced | |
141 | */ | |
142 | void fastcall mark_page_accessed(struct page *page) | |
143 | { | |
144 | if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) { | |
145 | activate_page(page); | |
146 | ClearPageReferenced(page); | |
147 | } else if (!PageReferenced(page)) { | |
148 | SetPageReferenced(page); | |
149 | } | |
150 | } | |
151 | ||
152 | EXPORT_SYMBOL(mark_page_accessed); | |
153 | ||
154 | /** | |
155 | * lru_cache_add: add a page to the page lists | |
156 | * @page: the page to add | |
157 | */ | |
158 | static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, }; | |
159 | static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, }; | |
160 | ||
161 | void fastcall lru_cache_add(struct page *page) | |
162 | { | |
163 | struct pagevec *pvec = &get_cpu_var(lru_add_pvecs); | |
164 | ||
165 | page_cache_get(page); | |
166 | if (!pagevec_add(pvec, page)) | |
167 | __pagevec_lru_add(pvec); | |
168 | put_cpu_var(lru_add_pvecs); | |
169 | } | |
170 | ||
171 | void fastcall lru_cache_add_active(struct page *page) | |
172 | { | |
173 | struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs); | |
174 | ||
175 | page_cache_get(page); | |
176 | if (!pagevec_add(pvec, page)) | |
177 | __pagevec_lru_add_active(pvec); | |
178 | put_cpu_var(lru_add_active_pvecs); | |
179 | } | |
180 | ||
80bfed90 | 181 | static void __lru_add_drain(int cpu) |
1da177e4 | 182 | { |
80bfed90 | 183 | struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu); |
1da177e4 | 184 | |
80bfed90 | 185 | /* CPU is dead, so no locking needed. */ |
1da177e4 LT |
186 | if (pagevec_count(pvec)) |
187 | __pagevec_lru_add(pvec); | |
80bfed90 | 188 | pvec = &per_cpu(lru_add_active_pvecs, cpu); |
1da177e4 LT |
189 | if (pagevec_count(pvec)) |
190 | __pagevec_lru_add_active(pvec); | |
80bfed90 AM |
191 | } |
192 | ||
193 | void lru_add_drain(void) | |
194 | { | |
195 | __lru_add_drain(get_cpu()); | |
196 | put_cpu(); | |
1da177e4 LT |
197 | } |
198 | ||
053837fc NP |
199 | #ifdef CONFIG_NUMA |
200 | static void lru_add_drain_per_cpu(void *dummy) | |
201 | { | |
202 | lru_add_drain(); | |
203 | } | |
204 | ||
205 | /* | |
206 | * Returns 0 for success | |
207 | */ | |
208 | int lru_add_drain_all(void) | |
209 | { | |
210 | return schedule_on_each_cpu(lru_add_drain_per_cpu, NULL); | |
211 | } | |
212 | ||
213 | #else | |
214 | ||
215 | /* | |
216 | * Returns 0 for success | |
217 | */ | |
218 | int lru_add_drain_all(void) | |
219 | { | |
220 | lru_add_drain(); | |
221 | return 0; | |
222 | } | |
223 | #endif | |
224 | ||
1da177e4 LT |
225 | /* |
226 | * This path almost never happens for VM activity - pages are normally | |
227 | * freed via pagevecs. But it gets used by networking. | |
228 | */ | |
229 | void fastcall __page_cache_release(struct page *page) | |
230 | { | |
46453a6e NP |
231 | if (PageLRU(page)) { |
232 | unsigned long flags; | |
233 | struct zone *zone = page_zone(page); | |
1da177e4 | 234 | |
46453a6e | 235 | spin_lock_irqsave(&zone->lru_lock, flags); |
8d438f96 | 236 | BUG_ON(!PageLRU(page)); |
67453911 | 237 | __ClearPageLRU(page); |
1da177e4 | 238 | del_page_from_lru(zone, page); |
46453a6e NP |
239 | spin_unlock_irqrestore(&zone->lru_lock, flags); |
240 | } | |
241 | free_hot_page(page); | |
1da177e4 | 242 | } |
1da177e4 LT |
243 | EXPORT_SYMBOL(__page_cache_release); |
244 | ||
245 | /* | |
246 | * Batched page_cache_release(). Decrement the reference count on all the | |
247 | * passed pages. If it fell to zero then remove the page from the LRU and | |
248 | * free it. | |
249 | * | |
250 | * Avoid taking zone->lru_lock if possible, but if it is taken, retain it | |
251 | * for the remainder of the operation. | |
252 | * | |
253 | * The locking in this function is against shrink_cache(): we recheck the | |
254 | * page count inside the lock to see whether shrink_cache grabbed the page | |
255 | * via the LRU. If it did, give up: shrink_cache will free it. | |
256 | */ | |
257 | void release_pages(struct page **pages, int nr, int cold) | |
258 | { | |
259 | int i; | |
260 | struct pagevec pages_to_free; | |
261 | struct zone *zone = NULL; | |
262 | ||
263 | pagevec_init(&pages_to_free, cold); | |
264 | for (i = 0; i < nr; i++) { | |
265 | struct page *page = pages[i]; | |
1da177e4 | 266 | |
8519fb30 NP |
267 | if (unlikely(PageCompound(page))) { |
268 | if (zone) { | |
269 | spin_unlock_irq(&zone->lru_lock); | |
270 | zone = NULL; | |
271 | } | |
272 | put_compound_page(page); | |
273 | continue; | |
274 | } | |
275 | ||
b5810039 | 276 | if (!put_page_testzero(page)) |
1da177e4 LT |
277 | continue; |
278 | ||
46453a6e NP |
279 | if (PageLRU(page)) { |
280 | struct zone *pagezone = page_zone(page); | |
281 | if (pagezone != zone) { | |
282 | if (zone) | |
283 | spin_unlock_irq(&zone->lru_lock); | |
284 | zone = pagezone; | |
285 | spin_lock_irq(&zone->lru_lock); | |
286 | } | |
8d438f96 | 287 | BUG_ON(!PageLRU(page)); |
67453911 | 288 | __ClearPageLRU(page); |
1da177e4 | 289 | del_page_from_lru(zone, page); |
46453a6e NP |
290 | } |
291 | ||
292 | if (!pagevec_add(&pages_to_free, page)) { | |
293 | if (zone) { | |
1da177e4 | 294 | spin_unlock_irq(&zone->lru_lock); |
46453a6e | 295 | zone = NULL; |
1da177e4 | 296 | } |
46453a6e NP |
297 | __pagevec_free(&pages_to_free); |
298 | pagevec_reinit(&pages_to_free); | |
299 | } | |
1da177e4 LT |
300 | } |
301 | if (zone) | |
302 | spin_unlock_irq(&zone->lru_lock); | |
303 | ||
304 | pagevec_free(&pages_to_free); | |
305 | } | |
306 | ||
307 | /* | |
308 | * The pages which we're about to release may be in the deferred lru-addition | |
309 | * queues. That would prevent them from really being freed right now. That's | |
310 | * OK from a correctness point of view but is inefficient - those pages may be | |
311 | * cache-warm and we want to give them back to the page allocator ASAP. | |
312 | * | |
313 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() | |
314 | * and __pagevec_lru_add_active() call release_pages() directly to avoid | |
315 | * mutual recursion. | |
316 | */ | |
317 | void __pagevec_release(struct pagevec *pvec) | |
318 | { | |
319 | lru_add_drain(); | |
320 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); | |
321 | pagevec_reinit(pvec); | |
322 | } | |
323 | ||
7f285701 SF |
324 | EXPORT_SYMBOL(__pagevec_release); |
325 | ||
1da177e4 LT |
326 | /* |
327 | * pagevec_release() for pages which are known to not be on the LRU | |
328 | * | |
329 | * This function reinitialises the caller's pagevec. | |
330 | */ | |
331 | void __pagevec_release_nonlru(struct pagevec *pvec) | |
332 | { | |
333 | int i; | |
334 | struct pagevec pages_to_free; | |
335 | ||
336 | pagevec_init(&pages_to_free, pvec->cold); | |
1da177e4 LT |
337 | for (i = 0; i < pagevec_count(pvec); i++) { |
338 | struct page *page = pvec->pages[i]; | |
339 | ||
340 | BUG_ON(PageLRU(page)); | |
341 | if (put_page_testzero(page)) | |
342 | pagevec_add(&pages_to_free, page); | |
343 | } | |
344 | pagevec_free(&pages_to_free); | |
345 | pagevec_reinit(pvec); | |
346 | } | |
347 | ||
348 | /* | |
349 | * Add the passed pages to the LRU, then drop the caller's refcount | |
350 | * on them. Reinitialises the caller's pagevec. | |
351 | */ | |
352 | void __pagevec_lru_add(struct pagevec *pvec) | |
353 | { | |
354 | int i; | |
355 | struct zone *zone = NULL; | |
356 | ||
357 | for (i = 0; i < pagevec_count(pvec); i++) { | |
358 | struct page *page = pvec->pages[i]; | |
359 | struct zone *pagezone = page_zone(page); | |
360 | ||
361 | if (pagezone != zone) { | |
362 | if (zone) | |
363 | spin_unlock_irq(&zone->lru_lock); | |
364 | zone = pagezone; | |
365 | spin_lock_irq(&zone->lru_lock); | |
366 | } | |
8d438f96 NP |
367 | BUG_ON(PageLRU(page)); |
368 | SetPageLRU(page); | |
1da177e4 LT |
369 | add_page_to_inactive_list(zone, page); |
370 | } | |
371 | if (zone) | |
372 | spin_unlock_irq(&zone->lru_lock); | |
373 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
374 | pagevec_reinit(pvec); | |
375 | } | |
376 | ||
377 | EXPORT_SYMBOL(__pagevec_lru_add); | |
378 | ||
379 | void __pagevec_lru_add_active(struct pagevec *pvec) | |
380 | { | |
381 | int i; | |
382 | struct zone *zone = NULL; | |
383 | ||
384 | for (i = 0; i < pagevec_count(pvec); i++) { | |
385 | struct page *page = pvec->pages[i]; | |
386 | struct zone *pagezone = page_zone(page); | |
387 | ||
388 | if (pagezone != zone) { | |
389 | if (zone) | |
390 | spin_unlock_irq(&zone->lru_lock); | |
391 | zone = pagezone; | |
392 | spin_lock_irq(&zone->lru_lock); | |
393 | } | |
8d438f96 NP |
394 | BUG_ON(PageLRU(page)); |
395 | SetPageLRU(page); | |
4c84cacf NP |
396 | BUG_ON(PageActive(page)); |
397 | SetPageActive(page); | |
1da177e4 LT |
398 | add_page_to_active_list(zone, page); |
399 | } | |
400 | if (zone) | |
401 | spin_unlock_irq(&zone->lru_lock); | |
402 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
403 | pagevec_reinit(pvec); | |
404 | } | |
405 | ||
406 | /* | |
407 | * Try to drop buffers from the pages in a pagevec | |
408 | */ | |
409 | void pagevec_strip(struct pagevec *pvec) | |
410 | { | |
411 | int i; | |
412 | ||
413 | for (i = 0; i < pagevec_count(pvec); i++) { | |
414 | struct page *page = pvec->pages[i]; | |
415 | ||
416 | if (PagePrivate(page) && !TestSetPageLocked(page)) { | |
5b40dc78 CL |
417 | if (PagePrivate(page)) |
418 | try_to_release_page(page, 0); | |
1da177e4 LT |
419 | unlock_page(page); |
420 | } | |
421 | } | |
422 | } | |
423 | ||
424 | /** | |
425 | * pagevec_lookup - gang pagecache lookup | |
426 | * @pvec: Where the resulting pages are placed | |
427 | * @mapping: The address_space to search | |
428 | * @start: The starting page index | |
429 | * @nr_pages: The maximum number of pages | |
430 | * | |
431 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages | |
432 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a | |
433 | * reference against the pages in @pvec. | |
434 | * | |
435 | * The search returns a group of mapping-contiguous pages with ascending | |
436 | * indexes. There may be holes in the indices due to not-present pages. | |
437 | * | |
438 | * pagevec_lookup() returns the number of pages which were found. | |
439 | */ | |
440 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, | |
441 | pgoff_t start, unsigned nr_pages) | |
442 | { | |
443 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); | |
444 | return pagevec_count(pvec); | |
445 | } | |
446 | ||
78539fdf CH |
447 | EXPORT_SYMBOL(pagevec_lookup); |
448 | ||
1da177e4 LT |
449 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, |
450 | pgoff_t *index, int tag, unsigned nr_pages) | |
451 | { | |
452 | pvec->nr = find_get_pages_tag(mapping, index, tag, | |
453 | nr_pages, pvec->pages); | |
454 | return pagevec_count(pvec); | |
455 | } | |
456 | ||
7f285701 | 457 | EXPORT_SYMBOL(pagevec_lookup_tag); |
1da177e4 LT |
458 | |
459 | #ifdef CONFIG_SMP | |
460 | /* | |
461 | * We tolerate a little inaccuracy to avoid ping-ponging the counter between | |
462 | * CPUs | |
463 | */ | |
464 | #define ACCT_THRESHOLD max(16, NR_CPUS * 2) | |
465 | ||
466 | static DEFINE_PER_CPU(long, committed_space) = 0; | |
467 | ||
468 | void vm_acct_memory(long pages) | |
469 | { | |
470 | long *local; | |
471 | ||
472 | preempt_disable(); | |
473 | local = &__get_cpu_var(committed_space); | |
474 | *local += pages; | |
475 | if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) { | |
476 | atomic_add(*local, &vm_committed_space); | |
477 | *local = 0; | |
478 | } | |
479 | preempt_enable(); | |
480 | } | |
1da177e4 LT |
481 | |
482 | #ifdef CONFIG_HOTPLUG_CPU | |
1da177e4 LT |
483 | |
484 | /* Drop the CPU's cached committed space back into the central pool. */ | |
485 | static int cpu_swap_callback(struct notifier_block *nfb, | |
486 | unsigned long action, | |
487 | void *hcpu) | |
488 | { | |
489 | long *committed; | |
490 | ||
491 | committed = &per_cpu(committed_space, (long)hcpu); | |
492 | if (action == CPU_DEAD) { | |
493 | atomic_add(*committed, &vm_committed_space); | |
494 | *committed = 0; | |
80bfed90 | 495 | __lru_add_drain((long)hcpu); |
1da177e4 LT |
496 | } |
497 | return NOTIFY_OK; | |
498 | } | |
499 | #endif /* CONFIG_HOTPLUG_CPU */ | |
500 | #endif /* CONFIG_SMP */ | |
501 | ||
1da177e4 LT |
502 | /* |
503 | * Perform any setup for the swap system | |
504 | */ | |
505 | void __init swap_setup(void) | |
506 | { | |
507 | unsigned long megs = num_physpages >> (20 - PAGE_SHIFT); | |
508 | ||
509 | /* Use a smaller cluster for small-memory machines */ | |
510 | if (megs < 16) | |
511 | page_cluster = 2; | |
512 | else | |
513 | page_cluster = 3; | |
514 | /* | |
515 | * Right now other parts of the system means that we | |
516 | * _really_ don't want to cluster much more | |
517 | */ | |
518 | hotcpu_notifier(cpu_swap_callback, 0); | |
519 | } |