]>
Commit | Line | Data |
---|---|---|
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 | ||
b221385b AB |
35 | /* |
36 | * This path almost never happens for VM activity - pages are normally | |
37 | * freed via pagevecs. But it gets used by networking. | |
38 | */ | |
39 | static void fastcall __page_cache_release(struct page *page) | |
40 | { | |
41 | if (PageLRU(page)) { | |
42 | unsigned long flags; | |
43 | struct zone *zone = page_zone(page); | |
44 | ||
45 | spin_lock_irqsave(&zone->lru_lock, flags); | |
46 | VM_BUG_ON(!PageLRU(page)); | |
47 | __ClearPageLRU(page); | |
48 | del_page_from_lru(zone, page); | |
49 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
50 | } | |
51 | free_hot_page(page); | |
52 | } | |
53 | ||
8519fb30 | 54 | static void put_compound_page(struct page *page) |
1da177e4 | 55 | { |
d85f3385 | 56 | page = compound_head(page); |
8519fb30 | 57 | if (put_page_testzero(page)) { |
33f2ef89 | 58 | compound_page_dtor *dtor; |
1da177e4 | 59 | |
33f2ef89 | 60 | dtor = get_compound_page_dtor(page); |
8519fb30 | 61 | (*dtor)(page); |
1da177e4 | 62 | } |
8519fb30 NP |
63 | } |
64 | ||
65 | void put_page(struct page *page) | |
66 | { | |
67 | if (unlikely(PageCompound(page))) | |
68 | put_compound_page(page); | |
69 | else if (put_page_testzero(page)) | |
1da177e4 LT |
70 | __page_cache_release(page); |
71 | } | |
72 | EXPORT_SYMBOL(put_page); | |
1da177e4 | 73 | |
1d7ea732 AZ |
74 | /** |
75 | * put_pages_list(): release a list of pages | |
76 | * | |
77 | * Release a list of pages which are strung together on page.lru. Currently | |
78 | * used by read_cache_pages() and related error recovery code. | |
79 | * | |
80 | * @pages: list of pages threaded on page->lru | |
81 | */ | |
82 | void put_pages_list(struct list_head *pages) | |
83 | { | |
84 | while (!list_empty(pages)) { | |
85 | struct page *victim; | |
86 | ||
87 | victim = list_entry(pages->prev, struct page, lru); | |
88 | list_del(&victim->lru); | |
89 | page_cache_release(victim); | |
90 | } | |
91 | } | |
92 | EXPORT_SYMBOL(put_pages_list); | |
93 | ||
1da177e4 LT |
94 | /* |
95 | * Writeback is about to end against a page which has been marked for immediate | |
96 | * reclaim. If it still appears to be reclaimable, move it to the tail of the | |
97 | * inactive list. The page still has PageWriteback set, which will pin it. | |
98 | * | |
99 | * We don't expect many pages to come through here, so don't bother batching | |
100 | * things up. | |
101 | * | |
102 | * To avoid placing the page at the tail of the LRU while PG_writeback is still | |
103 | * set, this function will clear PG_writeback before performing the page | |
104 | * motion. Do that inside the lru lock because once PG_writeback is cleared | |
105 | * we may not touch the page. | |
106 | * | |
107 | * Returns zero if it cleared PG_writeback. | |
108 | */ | |
109 | int rotate_reclaimable_page(struct page *page) | |
110 | { | |
111 | struct zone *zone; | |
112 | unsigned long flags; | |
113 | ||
114 | if (PageLocked(page)) | |
115 | return 1; | |
116 | if (PageDirty(page)) | |
117 | return 1; | |
118 | if (PageActive(page)) | |
119 | return 1; | |
120 | if (!PageLRU(page)) | |
121 | return 1; | |
122 | ||
123 | zone = page_zone(page); | |
124 | spin_lock_irqsave(&zone->lru_lock, flags); | |
125 | if (PageLRU(page) && !PageActive(page)) { | |
1bfba4e8 | 126 | list_move_tail(&page->lru, &zone->inactive_list); |
f8891e5e | 127 | __count_vm_event(PGROTATED); |
1da177e4 LT |
128 | } |
129 | if (!test_clear_page_writeback(page)) | |
130 | BUG(); | |
131 | spin_unlock_irqrestore(&zone->lru_lock, flags); | |
132 | return 0; | |
133 | } | |
134 | ||
135 | /* | |
136 | * FIXME: speed this up? | |
137 | */ | |
138 | void fastcall activate_page(struct page *page) | |
139 | { | |
140 | struct zone *zone = page_zone(page); | |
141 | ||
142 | spin_lock_irq(&zone->lru_lock); | |
143 | if (PageLRU(page) && !PageActive(page)) { | |
144 | del_page_from_inactive_list(zone, page); | |
145 | SetPageActive(page); | |
146 | add_page_to_active_list(zone, page); | |
f8891e5e | 147 | __count_vm_event(PGACTIVATE); |
1da177e4 LT |
148 | } |
149 | spin_unlock_irq(&zone->lru_lock); | |
150 | } | |
151 | ||
152 | /* | |
153 | * Mark a page as having seen activity. | |
154 | * | |
155 | * inactive,unreferenced -> inactive,referenced | |
156 | * inactive,referenced -> active,unreferenced | |
157 | * active,unreferenced -> active,referenced | |
158 | */ | |
159 | void fastcall mark_page_accessed(struct page *page) | |
160 | { | |
161 | if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) { | |
162 | activate_page(page); | |
163 | ClearPageReferenced(page); | |
164 | } else if (!PageReferenced(page)) { | |
165 | SetPageReferenced(page); | |
166 | } | |
167 | } | |
168 | ||
169 | EXPORT_SYMBOL(mark_page_accessed); | |
170 | ||
171 | /** | |
172 | * lru_cache_add: add a page to the page lists | |
173 | * @page: the page to add | |
174 | */ | |
175 | static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, }; | |
176 | static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, }; | |
177 | ||
178 | void fastcall lru_cache_add(struct page *page) | |
179 | { | |
180 | struct pagevec *pvec = &get_cpu_var(lru_add_pvecs); | |
181 | ||
182 | page_cache_get(page); | |
183 | if (!pagevec_add(pvec, page)) | |
184 | __pagevec_lru_add(pvec); | |
185 | put_cpu_var(lru_add_pvecs); | |
186 | } | |
187 | ||
188 | void fastcall lru_cache_add_active(struct page *page) | |
189 | { | |
190 | struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs); | |
191 | ||
192 | page_cache_get(page); | |
193 | if (!pagevec_add(pvec, page)) | |
194 | __pagevec_lru_add_active(pvec); | |
195 | put_cpu_var(lru_add_active_pvecs); | |
196 | } | |
197 | ||
80bfed90 | 198 | static void __lru_add_drain(int cpu) |
1da177e4 | 199 | { |
80bfed90 | 200 | struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu); |
1da177e4 | 201 | |
80bfed90 | 202 | /* CPU is dead, so no locking needed. */ |
1da177e4 LT |
203 | if (pagevec_count(pvec)) |
204 | __pagevec_lru_add(pvec); | |
80bfed90 | 205 | pvec = &per_cpu(lru_add_active_pvecs, cpu); |
1da177e4 LT |
206 | if (pagevec_count(pvec)) |
207 | __pagevec_lru_add_active(pvec); | |
80bfed90 AM |
208 | } |
209 | ||
210 | void lru_add_drain(void) | |
211 | { | |
212 | __lru_add_drain(get_cpu()); | |
213 | put_cpu(); | |
1da177e4 LT |
214 | } |
215 | ||
053837fc | 216 | #ifdef CONFIG_NUMA |
c4028958 | 217 | static void lru_add_drain_per_cpu(struct work_struct *dummy) |
053837fc NP |
218 | { |
219 | lru_add_drain(); | |
220 | } | |
221 | ||
222 | /* | |
223 | * Returns 0 for success | |
224 | */ | |
225 | int lru_add_drain_all(void) | |
226 | { | |
c4028958 | 227 | return schedule_on_each_cpu(lru_add_drain_per_cpu); |
053837fc NP |
228 | } |
229 | ||
230 | #else | |
231 | ||
232 | /* | |
233 | * Returns 0 for success | |
234 | */ | |
235 | int lru_add_drain_all(void) | |
236 | { | |
237 | lru_add_drain(); | |
238 | return 0; | |
239 | } | |
240 | #endif | |
241 | ||
1da177e4 LT |
242 | /* |
243 | * Batched page_cache_release(). Decrement the reference count on all the | |
244 | * passed pages. If it fell to zero then remove the page from the LRU and | |
245 | * free it. | |
246 | * | |
247 | * Avoid taking zone->lru_lock if possible, but if it is taken, retain it | |
248 | * for the remainder of the operation. | |
249 | * | |
250 | * The locking in this function is against shrink_cache(): we recheck the | |
251 | * page count inside the lock to see whether shrink_cache grabbed the page | |
252 | * via the LRU. If it did, give up: shrink_cache will free it. | |
253 | */ | |
254 | void release_pages(struct page **pages, int nr, int cold) | |
255 | { | |
256 | int i; | |
257 | struct pagevec pages_to_free; | |
258 | struct zone *zone = NULL; | |
259 | ||
260 | pagevec_init(&pages_to_free, cold); | |
261 | for (i = 0; i < nr; i++) { | |
262 | struct page *page = pages[i]; | |
1da177e4 | 263 | |
8519fb30 NP |
264 | if (unlikely(PageCompound(page))) { |
265 | if (zone) { | |
266 | spin_unlock_irq(&zone->lru_lock); | |
267 | zone = NULL; | |
268 | } | |
269 | put_compound_page(page); | |
270 | continue; | |
271 | } | |
272 | ||
b5810039 | 273 | if (!put_page_testzero(page)) |
1da177e4 LT |
274 | continue; |
275 | ||
46453a6e NP |
276 | if (PageLRU(page)) { |
277 | struct zone *pagezone = page_zone(page); | |
278 | if (pagezone != zone) { | |
279 | if (zone) | |
280 | spin_unlock_irq(&zone->lru_lock); | |
281 | zone = pagezone; | |
282 | spin_lock_irq(&zone->lru_lock); | |
283 | } | |
725d704e | 284 | VM_BUG_ON(!PageLRU(page)); |
67453911 | 285 | __ClearPageLRU(page); |
1da177e4 | 286 | del_page_from_lru(zone, page); |
46453a6e NP |
287 | } |
288 | ||
289 | if (!pagevec_add(&pages_to_free, page)) { | |
290 | if (zone) { | |
1da177e4 | 291 | spin_unlock_irq(&zone->lru_lock); |
46453a6e | 292 | zone = NULL; |
1da177e4 | 293 | } |
46453a6e NP |
294 | __pagevec_free(&pages_to_free); |
295 | pagevec_reinit(&pages_to_free); | |
296 | } | |
1da177e4 LT |
297 | } |
298 | if (zone) | |
299 | spin_unlock_irq(&zone->lru_lock); | |
300 | ||
301 | pagevec_free(&pages_to_free); | |
302 | } | |
303 | ||
304 | /* | |
305 | * The pages which we're about to release may be in the deferred lru-addition | |
306 | * queues. That would prevent them from really being freed right now. That's | |
307 | * OK from a correctness point of view but is inefficient - those pages may be | |
308 | * cache-warm and we want to give them back to the page allocator ASAP. | |
309 | * | |
310 | * So __pagevec_release() will drain those queues here. __pagevec_lru_add() | |
311 | * and __pagevec_lru_add_active() call release_pages() directly to avoid | |
312 | * mutual recursion. | |
313 | */ | |
314 | void __pagevec_release(struct pagevec *pvec) | |
315 | { | |
316 | lru_add_drain(); | |
317 | release_pages(pvec->pages, pagevec_count(pvec), pvec->cold); | |
318 | pagevec_reinit(pvec); | |
319 | } | |
320 | ||
7f285701 SF |
321 | EXPORT_SYMBOL(__pagevec_release); |
322 | ||
1da177e4 LT |
323 | /* |
324 | * pagevec_release() for pages which are known to not be on the LRU | |
325 | * | |
326 | * This function reinitialises the caller's pagevec. | |
327 | */ | |
328 | void __pagevec_release_nonlru(struct pagevec *pvec) | |
329 | { | |
330 | int i; | |
331 | struct pagevec pages_to_free; | |
332 | ||
333 | pagevec_init(&pages_to_free, pvec->cold); | |
1da177e4 LT |
334 | for (i = 0; i < pagevec_count(pvec); i++) { |
335 | struct page *page = pvec->pages[i]; | |
336 | ||
725d704e | 337 | VM_BUG_ON(PageLRU(page)); |
1da177e4 LT |
338 | if (put_page_testzero(page)) |
339 | pagevec_add(&pages_to_free, page); | |
340 | } | |
341 | pagevec_free(&pages_to_free); | |
342 | pagevec_reinit(pvec); | |
343 | } | |
344 | ||
345 | /* | |
346 | * Add the passed pages to the LRU, then drop the caller's refcount | |
347 | * on them. Reinitialises the caller's pagevec. | |
348 | */ | |
349 | void __pagevec_lru_add(struct pagevec *pvec) | |
350 | { | |
351 | int i; | |
352 | struct zone *zone = NULL; | |
353 | ||
354 | for (i = 0; i < pagevec_count(pvec); i++) { | |
355 | struct page *page = pvec->pages[i]; | |
356 | struct zone *pagezone = page_zone(page); | |
357 | ||
358 | if (pagezone != zone) { | |
359 | if (zone) | |
360 | spin_unlock_irq(&zone->lru_lock); | |
361 | zone = pagezone; | |
362 | spin_lock_irq(&zone->lru_lock); | |
363 | } | |
725d704e | 364 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 365 | SetPageLRU(page); |
1da177e4 LT |
366 | add_page_to_inactive_list(zone, page); |
367 | } | |
368 | if (zone) | |
369 | spin_unlock_irq(&zone->lru_lock); | |
370 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
371 | pagevec_reinit(pvec); | |
372 | } | |
373 | ||
374 | EXPORT_SYMBOL(__pagevec_lru_add); | |
375 | ||
376 | void __pagevec_lru_add_active(struct pagevec *pvec) | |
377 | { | |
378 | int i; | |
379 | struct zone *zone = NULL; | |
380 | ||
381 | for (i = 0; i < pagevec_count(pvec); i++) { | |
382 | struct page *page = pvec->pages[i]; | |
383 | struct zone *pagezone = page_zone(page); | |
384 | ||
385 | if (pagezone != zone) { | |
386 | if (zone) | |
387 | spin_unlock_irq(&zone->lru_lock); | |
388 | zone = pagezone; | |
389 | spin_lock_irq(&zone->lru_lock); | |
390 | } | |
725d704e | 391 | VM_BUG_ON(PageLRU(page)); |
8d438f96 | 392 | SetPageLRU(page); |
725d704e | 393 | VM_BUG_ON(PageActive(page)); |
4c84cacf | 394 | SetPageActive(page); |
1da177e4 LT |
395 | add_page_to_active_list(zone, page); |
396 | } | |
397 | if (zone) | |
398 | spin_unlock_irq(&zone->lru_lock); | |
399 | release_pages(pvec->pages, pvec->nr, pvec->cold); | |
400 | pagevec_reinit(pvec); | |
401 | } | |
402 | ||
403 | /* | |
404 | * Try to drop buffers from the pages in a pagevec | |
405 | */ | |
406 | void pagevec_strip(struct pagevec *pvec) | |
407 | { | |
408 | int i; | |
409 | ||
410 | for (i = 0; i < pagevec_count(pvec); i++) { | |
411 | struct page *page = pvec->pages[i]; | |
412 | ||
413 | if (PagePrivate(page) && !TestSetPageLocked(page)) { | |
5b40dc78 CL |
414 | if (PagePrivate(page)) |
415 | try_to_release_page(page, 0); | |
1da177e4 LT |
416 | unlock_page(page); |
417 | } | |
418 | } | |
419 | } | |
420 | ||
421 | /** | |
422 | * pagevec_lookup - gang pagecache lookup | |
423 | * @pvec: Where the resulting pages are placed | |
424 | * @mapping: The address_space to search | |
425 | * @start: The starting page index | |
426 | * @nr_pages: The maximum number of pages | |
427 | * | |
428 | * pagevec_lookup() will search for and return a group of up to @nr_pages pages | |
429 | * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a | |
430 | * reference against the pages in @pvec. | |
431 | * | |
432 | * The search returns a group of mapping-contiguous pages with ascending | |
433 | * indexes. There may be holes in the indices due to not-present pages. | |
434 | * | |
435 | * pagevec_lookup() returns the number of pages which were found. | |
436 | */ | |
437 | unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping, | |
438 | pgoff_t start, unsigned nr_pages) | |
439 | { | |
440 | pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages); | |
441 | return pagevec_count(pvec); | |
442 | } | |
443 | ||
78539fdf CH |
444 | EXPORT_SYMBOL(pagevec_lookup); |
445 | ||
1da177e4 LT |
446 | unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping, |
447 | pgoff_t *index, int tag, unsigned nr_pages) | |
448 | { | |
449 | pvec->nr = find_get_pages_tag(mapping, index, tag, | |
450 | nr_pages, pvec->pages); | |
451 | return pagevec_count(pvec); | |
452 | } | |
453 | ||
7f285701 | 454 | EXPORT_SYMBOL(pagevec_lookup_tag); |
1da177e4 LT |
455 | |
456 | #ifdef CONFIG_SMP | |
457 | /* | |
458 | * We tolerate a little inaccuracy to avoid ping-ponging the counter between | |
459 | * CPUs | |
460 | */ | |
461 | #define ACCT_THRESHOLD max(16, NR_CPUS * 2) | |
462 | ||
463 | static DEFINE_PER_CPU(long, committed_space) = 0; | |
464 | ||
465 | void vm_acct_memory(long pages) | |
466 | { | |
467 | long *local; | |
468 | ||
469 | preempt_disable(); | |
470 | local = &__get_cpu_var(committed_space); | |
471 | *local += pages; | |
472 | if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) { | |
473 | atomic_add(*local, &vm_committed_space); | |
474 | *local = 0; | |
475 | } | |
476 | preempt_enable(); | |
477 | } | |
1da177e4 LT |
478 | |
479 | #ifdef CONFIG_HOTPLUG_CPU | |
1da177e4 LT |
480 | |
481 | /* Drop the CPU's cached committed space back into the central pool. */ | |
482 | static int cpu_swap_callback(struct notifier_block *nfb, | |
483 | unsigned long action, | |
484 | void *hcpu) | |
485 | { | |
486 | long *committed; | |
487 | ||
488 | committed = &per_cpu(committed_space, (long)hcpu); | |
8bb78442 | 489 | if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) { |
1da177e4 LT |
490 | atomic_add(*committed, &vm_committed_space); |
491 | *committed = 0; | |
80bfed90 | 492 | __lru_add_drain((long)hcpu); |
1da177e4 LT |
493 | } |
494 | return NOTIFY_OK; | |
495 | } | |
496 | #endif /* CONFIG_HOTPLUG_CPU */ | |
497 | #endif /* CONFIG_SMP */ | |
498 | ||
1da177e4 LT |
499 | /* |
500 | * Perform any setup for the swap system | |
501 | */ | |
502 | void __init swap_setup(void) | |
503 | { | |
504 | unsigned long megs = num_physpages >> (20 - PAGE_SHIFT); | |
505 | ||
506 | /* Use a smaller cluster for small-memory machines */ | |
507 | if (megs < 16) | |
508 | page_cluster = 2; | |
509 | else | |
510 | page_cluster = 3; | |
511 | /* | |
512 | * Right now other parts of the system means that we | |
513 | * _really_ don't want to cluster much more | |
514 | */ | |
02316067 | 515 | #ifdef CONFIG_HOTPLUG_CPU |
1da177e4 | 516 | hotcpu_notifier(cpu_swap_callback, 0); |
02316067 | 517 | #endif |
1da177e4 | 518 | } |