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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 LT |
56 | |
57 | /* | |
58 | * Writeback is about to end against a page which has been marked for immediate | |
59 | * reclaim. If it still appears to be reclaimable, move it to the tail of the | |
60 | * inactive list. The page still has PageWriteback set, which will pin it. | |
61 | * | |
62 | * We don't expect many pages to come through here, so don't bother batching | |
63 | * things up. | |
64 | * | |
65 | * To avoid placing the page at the tail of the LRU while PG_writeback is still | |
66 | * set, this function will clear PG_writeback before performing the page | |
67 | * motion. Do that inside the lru lock because once PG_writeback is cleared | |
68 | * we may not touch the page. | |
69 | * | |
70 | * Returns zero if it cleared PG_writeback. | |
71 | */ | |
72 | int rotate_reclaimable_page(struct page *page) | |
73 | { | |
74 | struct zone *zone; | |
75 | unsigned long flags; | |
76 | ||
77 | if (PageLocked(page)) | |
78 | return 1; | |
79 | if (PageDirty(page)) | |
80 | return 1; | |
81 | if (PageActive(page)) | |
82 | return 1; | |
83 | if (!PageLRU(page)) | |
84 | return 1; | |
85 | ||
86 | zone = page_zone(page); | |
87 | spin_lock_irqsave(&zone->lru_lock, flags); | |
88 | if (PageLRU(page) && !PageActive(page)) { | |
89 | list_del(&page->lru); | |
90 | list_add_tail(&page->lru, &zone->inactive_list); | |
91 | inc_page_state(pgrotated); | |
92 | } | |
93 | if (!test_clear_page_writeback(page)) | |
94 | BUG(); | |
95 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
96 | return 0; | |
97 | } | |
98 | ||
99 | /* | |
100 | * FIXME: speed this up? | |
101 | */ | |
102 | void fastcall activate_page(struct page *page) | |
103 | { | |
104 | struct zone *zone = page_zone(page); | |
105 | ||
106 | spin_lock_irq(&zone->lru_lock); | |
107 | if (PageLRU(page) && !PageActive(page)) { | |
108 | del_page_from_inactive_list(zone, page); | |
109 | SetPageActive(page); | |
110 | add_page_to_active_list(zone, page); | |
111 | inc_page_state(pgactivate); | |
112 | } | |
113 | spin_unlock_irq(&zone->lru_lock); | |
114 | } | |
115 | ||
116 | /* | |
117 | * Mark a page as having seen activity. | |
118 | * | |
119 | * inactive,unreferenced -> inactive,referenced | |
120 | * inactive,referenced -> active,unreferenced | |
121 | * active,unreferenced -> active,referenced | |
122 | */ | |
123 | void fastcall mark_page_accessed(struct page *page) | |
124 | { | |
125 | if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) { | |
126 | activate_page(page); | |
127 | ClearPageReferenced(page); | |
128 | } else if (!PageReferenced(page)) { | |
129 | SetPageReferenced(page); | |
130 | } | |
131 | } | |
132 | ||
133 | EXPORT_SYMBOL(mark_page_accessed); | |
134 | ||
135 | /** | |
136 | * lru_cache_add: add a page to the page lists | |
137 | * @page: the page to add | |
138 | */ | |
139 | static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, }; | |
140 | static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, }; | |
141 | ||
142 | void fastcall lru_cache_add(struct page *page) | |
143 | { | |
144 | struct pagevec *pvec = &get_cpu_var(lru_add_pvecs); | |
145 | ||
146 | page_cache_get(page); | |
147 | if (!pagevec_add(pvec, page)) | |
148 | __pagevec_lru_add(pvec); | |
149 | put_cpu_var(lru_add_pvecs); | |
150 | } | |
151 | ||
152 | void fastcall lru_cache_add_active(struct page *page) | |
153 | { | |
154 | struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs); | |
155 | ||
156 | page_cache_get(page); | |
157 | if (!pagevec_add(pvec, page)) | |
158 | __pagevec_lru_add_active(pvec); | |
159 | put_cpu_var(lru_add_active_pvecs); | |
160 | } | |
161 | ||
80bfed90 | 162 | static void __lru_add_drain(int cpu) |
1da177e4 | 163 | { |
80bfed90 | 164 | struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu); |
1da177e4 | 165 | |
80bfed90 | 166 | /* CPU is dead, so no locking needed. */ |
1da177e4 LT |
167 | if (pagevec_count(pvec)) |
168 | __pagevec_lru_add(pvec); | |
80bfed90 | 169 | pvec = &per_cpu(lru_add_active_pvecs, cpu); |
1da177e4 LT |
170 | if (pagevec_count(pvec)) |
171 | __pagevec_lru_add_active(pvec); | |
80bfed90 AM |
172 | } |
173 | ||
174 | void lru_add_drain(void) | |
175 | { | |
176 | __lru_add_drain(get_cpu()); | |
177 | put_cpu(); | |
1da177e4 LT |
178 | } |
179 | ||
053837fc NP |
180 | #ifdef CONFIG_NUMA |
181 | static void lru_add_drain_per_cpu(void *dummy) | |
182 | { | |
183 | lru_add_drain(); | |
184 | } | |
185 | ||
186 | /* | |
187 | * Returns 0 for success | |
188 | */ | |
189 | int lru_add_drain_all(void) | |
190 | { | |
191 | return schedule_on_each_cpu(lru_add_drain_per_cpu, NULL); | |
192 | } | |
193 | ||
194 | #else | |
195 | ||
196 | /* | |
197 | * Returns 0 for success | |
198 | */ | |
199 | int lru_add_drain_all(void) | |
200 | { | |
201 | lru_add_drain(); | |
202 | return 0; | |
203 | } | |
204 | #endif | |
205 | ||
1da177e4 LT |
206 | /* |
207 | * This path almost never happens for VM activity - pages are normally | |
208 | * freed via pagevecs. But it gets used by networking. | |
209 | */ | |
210 | void fastcall __page_cache_release(struct page *page) | |
211 | { | |
212 | unsigned long flags; | |
213 | struct zone *zone = page_zone(page); | |
214 | ||
215 | spin_lock_irqsave(&zone->lru_lock, flags); | |
216 | if (TestClearPageLRU(page)) | |
217 | del_page_from_lru(zone, page); | |
218 | if (page_count(page) != 0) | |
219 | page = NULL; | |
220 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
221 | if (page) | |
222 | free_hot_page(page); | |
223 | } | |
224 | ||
225 | EXPORT_SYMBOL(__page_cache_release); | |
226 | ||
227 | /* | |
228 | * Batched page_cache_release(). Decrement the reference count on all the | |
229 | * passed pages. If it fell to zero then remove the page from the LRU and | |
230 | * free it. | |
231 | * | |
232 | * Avoid taking zone->lru_lock if possible, but if it is taken, retain it | |
233 | * for the remainder of the operation. | |
234 | * | |
235 | * The locking in this function is against shrink_cache(): we recheck the | |
236 | * page count inside the lock to see whether shrink_cache grabbed the page | |
237 | * via the LRU. If it did, give up: shrink_cache will free it. | |
238 | */ | |
239 | void release_pages(struct page **pages, int nr, int cold) | |
240 | { | |
241 | int i; | |
242 | struct pagevec pages_to_free; | |
243 | struct zone *zone = NULL; | |
244 | ||
245 | pagevec_init(&pages_to_free, cold); | |
246 | for (i = 0; i < nr; i++) { | |
247 | struct page *page = pages[i]; | |
248 | struct zone *pagezone; | |
249 | ||
8519fb30 NP |
250 | if (unlikely(PageCompound(page))) { |
251 | if (zone) { | |
252 | spin_unlock_irq(&zone->lru_lock); | |
253 | zone = NULL; | |
254 | } | |
255 | put_compound_page(page); | |
256 | continue; | |
257 | } | |
258 | ||
b5810039 | 259 | if (!put_page_testzero(page)) |
1da177e4 LT |
260 | continue; |
261 | ||
262 | pagezone = page_zone(page); | |
263 | if (pagezone != zone) { | |
264 | if (zone) | |
265 | spin_unlock_irq(&zone->lru_lock); | |
266 | zone = pagezone; | |
267 | spin_lock_irq(&zone->lru_lock); | |
268 | } | |
269 | if (TestClearPageLRU(page)) | |
270 | del_page_from_lru(zone, page); | |
271 | if (page_count(page) == 0) { | |
272 | if (!pagevec_add(&pages_to_free, page)) { | |
273 | spin_unlock_irq(&zone->lru_lock); | |
274 | __pagevec_free(&pages_to_free); | |
275 | pagevec_reinit(&pages_to_free); | |
276 | zone = NULL; /* No lock is held */ | |
277 | } | |
278 | } | |
279 | } | |
280 | if (zone) | |
281 | spin_unlock_irq(&zone->lru_lock); | |
282 | ||
283 | pagevec_free(&pages_to_free); | |
284 | } | |
285 | ||
286 | /* | |
287 | * The pages which we're about to release may be in the deferred lru-addition | |
288 | * queues. That would prevent them from really being freed right now. That's | |
289 | * OK from a correctness point of view but is inefficient - those pages may be | |
290 | * cache-warm and we want to give them back to the page allocator ASAP. | |
291 | * | |
292 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() | |
293 | * and __pagevec_lru_add_active() call release_pages() directly to avoid | |
294 | * mutual recursion. | |
295 | */ | |
296 | void __pagevec_release(struct pagevec *pvec) | |
297 | { | |
298 | lru_add_drain(); | |
299 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); | |
300 | pagevec_reinit(pvec); | |
301 | } | |
302 | ||
7f285701 SF |
303 | EXPORT_SYMBOL(__pagevec_release); |
304 | ||
1da177e4 LT |
305 | /* |
306 | * pagevec_release() for pages which are known to not be on the LRU | |
307 | * | |
308 | * This function reinitialises the caller's pagevec. | |
309 | */ | |
310 | void __pagevec_release_nonlru(struct pagevec *pvec) | |
311 | { | |
312 | int i; | |
313 | struct pagevec pages_to_free; | |
314 | ||
315 | pagevec_init(&pages_to_free, pvec->cold); | |
1da177e4 LT |
316 | for (i = 0; i < pagevec_count(pvec); i++) { |
317 | struct page *page = pvec->pages[i]; | |
318 | ||
319 | BUG_ON(PageLRU(page)); | |
320 | if (put_page_testzero(page)) | |
321 | pagevec_add(&pages_to_free, page); | |
322 | } | |
323 | pagevec_free(&pages_to_free); | |
324 | pagevec_reinit(pvec); | |
325 | } | |
326 | ||
327 | /* | |
328 | * Add the passed pages to the LRU, then drop the caller's refcount | |
329 | * on them. Reinitialises the caller's pagevec. | |
330 | */ | |
331 | void __pagevec_lru_add(struct pagevec *pvec) | |
332 | { | |
333 | int i; | |
334 | struct zone *zone = NULL; | |
335 | ||
336 | for (i = 0; i < pagevec_count(pvec); i++) { | |
337 | struct page *page = pvec->pages[i]; | |
338 | struct zone *pagezone = page_zone(page); | |
339 | ||
340 | if (pagezone != zone) { | |
341 | if (zone) | |
342 | spin_unlock_irq(&zone->lru_lock); | |
343 | zone = pagezone; | |
344 | spin_lock_irq(&zone->lru_lock); | |
345 | } | |
346 | if (TestSetPageLRU(page)) | |
347 | BUG(); | |
348 | add_page_to_inactive_list(zone, page); | |
349 | } | |
350 | if (zone) | |
351 | spin_unlock_irq(&zone->lru_lock); | |
352 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
353 | pagevec_reinit(pvec); | |
354 | } | |
355 | ||
356 | EXPORT_SYMBOL(__pagevec_lru_add); | |
357 | ||
358 | void __pagevec_lru_add_active(struct pagevec *pvec) | |
359 | { | |
360 | int i; | |
361 | struct zone *zone = NULL; | |
362 | ||
363 | for (i = 0; i < pagevec_count(pvec); i++) { | |
364 | struct page *page = pvec->pages[i]; | |
365 | struct zone *pagezone = page_zone(page); | |
366 | ||
367 | if (pagezone != zone) { | |
368 | if (zone) | |
369 | spin_unlock_irq(&zone->lru_lock); | |
370 | zone = pagezone; | |
371 | spin_lock_irq(&zone->lru_lock); | |
372 | } | |
373 | if (TestSetPageLRU(page)) | |
374 | BUG(); | |
375 | if (TestSetPageActive(page)) | |
376 | BUG(); | |
377 | add_page_to_active_list(zone, page); | |
378 | } | |
379 | if (zone) | |
380 | spin_unlock_irq(&zone->lru_lock); | |
381 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
382 | pagevec_reinit(pvec); | |
383 | } | |
384 | ||
385 | /* | |
386 | * Try to drop buffers from the pages in a pagevec | |
387 | */ | |
388 | void pagevec_strip(struct pagevec *pvec) | |
389 | { | |
390 | int i; | |
391 | ||
392 | for (i = 0; i < pagevec_count(pvec); i++) { | |
393 | struct page *page = pvec->pages[i]; | |
394 | ||
395 | if (PagePrivate(page) && !TestSetPageLocked(page)) { | |
396 | try_to_release_page(page, 0); | |
397 | unlock_page(page); | |
398 | } | |
399 | } | |
400 | } | |
401 | ||
402 | /** | |
403 | * pagevec_lookup - gang pagecache lookup | |
404 | * @pvec: Where the resulting pages are placed | |
405 | * @mapping: The address_space to search | |
406 | * @start: The starting page index | |
407 | * @nr_pages: The maximum number of pages | |
408 | * | |
409 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages | |
410 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a | |
411 | * reference against the pages in @pvec. | |
412 | * | |
413 | * The search returns a group of mapping-contiguous pages with ascending | |
414 | * indexes. There may be holes in the indices due to not-present pages. | |
415 | * | |
416 | * pagevec_lookup() returns the number of pages which were found. | |
417 | */ | |
418 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, | |
419 | pgoff_t start, unsigned nr_pages) | |
420 | { | |
421 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); | |
422 | return pagevec_count(pvec); | |
423 | } | |
424 | ||
78539fdf CH |
425 | EXPORT_SYMBOL(pagevec_lookup); |
426 | ||
1da177e4 LT |
427 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, |
428 | pgoff_t *index, int tag, unsigned nr_pages) | |
429 | { | |
430 | pvec->nr = find_get_pages_tag(mapping, index, tag, | |
431 | nr_pages, pvec->pages); | |
432 | return pagevec_count(pvec); | |
433 | } | |
434 | ||
7f285701 | 435 | EXPORT_SYMBOL(pagevec_lookup_tag); |
1da177e4 LT |
436 | |
437 | #ifdef CONFIG_SMP | |
438 | /* | |
439 | * We tolerate a little inaccuracy to avoid ping-ponging the counter between | |
440 | * CPUs | |
441 | */ | |
442 | #define ACCT_THRESHOLD max(16, NR_CPUS * 2) | |
443 | ||
444 | static DEFINE_PER_CPU(long, committed_space) = 0; | |
445 | ||
446 | void vm_acct_memory(long pages) | |
447 | { | |
448 | long *local; | |
449 | ||
450 | preempt_disable(); | |
451 | local = &__get_cpu_var(committed_space); | |
452 | *local += pages; | |
453 | if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) { | |
454 | atomic_add(*local, &vm_committed_space); | |
455 | *local = 0; | |
456 | } | |
457 | preempt_enable(); | |
458 | } | |
1da177e4 LT |
459 | |
460 | #ifdef CONFIG_HOTPLUG_CPU | |
1da177e4 LT |
461 | |
462 | /* Drop the CPU's cached committed space back into the central pool. */ | |
463 | static int cpu_swap_callback(struct notifier_block *nfb, | |
464 | unsigned long action, | |
465 | void *hcpu) | |
466 | { | |
467 | long *committed; | |
468 | ||
469 | committed = &per_cpu(committed_space, (long)hcpu); | |
470 | if (action == CPU_DEAD) { | |
471 | atomic_add(*committed, &vm_committed_space); | |
472 | *committed = 0; | |
80bfed90 | 473 | __lru_add_drain((long)hcpu); |
1da177e4 LT |
474 | } |
475 | return NOTIFY_OK; | |
476 | } | |
477 | #endif /* CONFIG_HOTPLUG_CPU */ | |
478 | #endif /* CONFIG_SMP */ | |
479 | ||
480 | #ifdef CONFIG_SMP | |
481 | void percpu_counter_mod(struct percpu_counter *fbc, long amount) | |
482 | { | |
483 | long count; | |
484 | long *pcount; | |
485 | int cpu = get_cpu(); | |
486 | ||
487 | pcount = per_cpu_ptr(fbc->counters, cpu); | |
488 | count = *pcount + amount; | |
489 | if (count >= FBC_BATCH || count <= -FBC_BATCH) { | |
490 | spin_lock(&fbc->lock); | |
491 | fbc->count += count; | |
e2bab3d9 | 492 | *pcount = 0; |
1da177e4 | 493 | spin_unlock(&fbc->lock); |
e2bab3d9 AM |
494 | } else { |
495 | *pcount = count; | |
1da177e4 | 496 | } |
1da177e4 LT |
497 | put_cpu(); |
498 | } | |
499 | EXPORT_SYMBOL(percpu_counter_mod); | |
e2bab3d9 AM |
500 | |
501 | /* | |
502 | * Add up all the per-cpu counts, return the result. This is a more accurate | |
503 | * but much slower version of percpu_counter_read_positive() | |
504 | */ | |
505 | long percpu_counter_sum(struct percpu_counter *fbc) | |
506 | { | |
507 | long ret; | |
508 | int cpu; | |
509 | ||
510 | spin_lock(&fbc->lock); | |
511 | ret = fbc->count; | |
512 | for_each_cpu(cpu) { | |
513 | long *pcount = per_cpu_ptr(fbc->counters, cpu); | |
514 | ret += *pcount; | |
515 | } | |
516 | spin_unlock(&fbc->lock); | |
517 | return ret < 0 ? 0 : ret; | |
518 | } | |
519 | EXPORT_SYMBOL(percpu_counter_sum); | |
1da177e4 LT |
520 | #endif |
521 | ||
522 | /* | |
523 | * Perform any setup for the swap system | |
524 | */ | |
525 | void __init swap_setup(void) | |
526 | { | |
527 | unsigned long megs = num_physpages >> (20 - PAGE_SHIFT); | |
528 | ||
529 | /* Use a smaller cluster for small-memory machines */ | |
530 | if (megs < 16) | |
531 | page_cluster = 2; | |
532 | else | |
533 | page_cluster = 3; | |
534 | /* | |
535 | * Right now other parts of the system means that we | |
536 | * _really_ don't want to cluster much more | |
537 | */ | |
538 | hotcpu_notifier(cpu_swap_callback, 0); | |
539 | } |