blob: 218c52a24a216831a347736cde51045563854770 [file] [log] [blame]
Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
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? */
35int page_cluster;
36
Adrian Bunkb2213852006-09-25 23:31:02 -070037/*
38 * This path almost never happens for VM activity - pages are normally
39 * freed via pagevecs. But it gets used by networking.
40 */
41static void fastcall __page_cache_release(struct page *page)
42{
43 if (PageLRU(page)) {
44 unsigned long flags;
45 struct zone *zone = page_zone(page);
46
47 spin_lock_irqsave(&zone->lru_lock, flags);
48 VM_BUG_ON(!PageLRU(page));
49 __ClearPageLRU(page);
50 del_page_from_lru(zone, page);
51 spin_unlock_irqrestore(&zone->lru_lock, flags);
52 }
53 free_hot_page(page);
54}
55
Nick Piggin8519fb32006-02-07 12:58:52 -080056static void put_compound_page(struct page *page)
57{
Christoph Lameterd85f3382007-05-06 14:49:39 -070058 page = compound_head(page);
Nick Piggin8519fb32006-02-07 12:58:52 -080059 if (put_page_testzero(page)) {
Andy Whitcroft33f2ef82006-12-06 20:33:32 -080060 compound_page_dtor *dtor;
Nick Piggin8519fb32006-02-07 12:58:52 -080061
Andy Whitcroft33f2ef82006-12-06 20:33:32 -080062 dtor = get_compound_page_dtor(page);
Nick Piggin8519fb32006-02-07 12:58:52 -080063 (*dtor)(page);
64 }
65}
66
Linus Torvalds1da177e2005-04-16 15:20:36 -070067void put_page(struct page *page)
68{
Nick Piggin8519fb32006-02-07 12:58:52 -080069 if (unlikely(PageCompound(page)))
70 put_compound_page(page);
71 else if (put_page_testzero(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -070072 __page_cache_release(page);
73}
74EXPORT_SYMBOL(put_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070075
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -070076/**
77 * put_pages_list(): release a list of pages
78 *
79 * Release a list of pages which are strung together on page.lru. Currently
80 * used by read_cache_pages() and related error recovery code.
81 *
82 * @pages: list of pages threaded on page->lru
83 */
84void put_pages_list(struct list_head *pages)
85{
86 while (!list_empty(pages)) {
87 struct page *victim;
88
89 victim = list_entry(pages->prev, struct page, lru);
90 list_del(&victim->lru);
91 page_cache_release(victim);
92 }
93}
94EXPORT_SYMBOL(put_pages_list);
95
Linus Torvalds1da177e2005-04-16 15:20:36 -070096/*
97 * Writeback is about to end against a page which has been marked for immediate
98 * reclaim. If it still appears to be reclaimable, move it to the tail of the
99 * inactive list. The page still has PageWriteback set, which will pin it.
100 *
101 * We don't expect many pages to come through here, so don't bother batching
102 * things up.
103 *
104 * To avoid placing the page at the tail of the LRU while PG_writeback is still
105 * set, this function will clear PG_writeback before performing the page
106 * motion. Do that inside the lru lock because once PG_writeback is cleared
107 * we may not touch the page.
108 *
109 * Returns zero if it cleared PG_writeback.
110 */
111int rotate_reclaimable_page(struct page *page)
112{
113 struct zone *zone;
114 unsigned long flags;
115
116 if (PageLocked(page))
117 return 1;
118 if (PageDirty(page))
119 return 1;
120 if (PageActive(page))
121 return 1;
122 if (!PageLRU(page))
123 return 1;
124
125 zone = page_zone(page);
126 spin_lock_irqsave(&zone->lru_lock, flags);
127 if (PageLRU(page) && !PageActive(page)) {
Akinobu Mita1bfba4e2006-06-26 00:24:40 -0700128 list_move_tail(&page->lru, &zone->inactive_list);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700129 __count_vm_event(PGROTATED);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700130 }
131 if (!test_clear_page_writeback(page))
132 BUG();
133 spin_unlock_irqrestore(&zone->lru_lock, flags);
134 return 0;
135}
136
137/*
138 * FIXME: speed this up?
139 */
140void fastcall activate_page(struct page *page)
141{
142 struct zone *zone = page_zone(page);
143
144 spin_lock_irq(&zone->lru_lock);
145 if (PageLRU(page) && !PageActive(page)) {
146 del_page_from_inactive_list(zone, page);
147 SetPageActive(page);
148 add_page_to_active_list(zone, page);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700149 __count_vm_event(PGACTIVATE);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700150 }
151 spin_unlock_irq(&zone->lru_lock);
152}
153
154/*
155 * Mark a page as having seen activity.
156 *
157 * inactive,unreferenced -> inactive,referenced
158 * inactive,referenced -> active,unreferenced
159 * active,unreferenced -> active,referenced
160 */
161void fastcall mark_page_accessed(struct page *page)
162{
163 if (!PageActive(page) && PageReferenced(page) && PageLRU(page)) {
164 activate_page(page);
165 ClearPageReferenced(page);
166 } else if (!PageReferenced(page)) {
167 SetPageReferenced(page);
168 }
169}
170
171EXPORT_SYMBOL(mark_page_accessed);
172
173/**
174 * lru_cache_add: add a page to the page lists
175 * @page: the page to add
176 */
177static DEFINE_PER_CPU(struct pagevec, lru_add_pvecs) = { 0, };
178static DEFINE_PER_CPU(struct pagevec, lru_add_active_pvecs) = { 0, };
179
180void fastcall lru_cache_add(struct page *page)
181{
182 struct pagevec *pvec = &get_cpu_var(lru_add_pvecs);
183
184 page_cache_get(page);
185 if (!pagevec_add(pvec, page))
186 __pagevec_lru_add(pvec);
187 put_cpu_var(lru_add_pvecs);
188}
189
190void fastcall lru_cache_add_active(struct page *page)
191{
192 struct pagevec *pvec = &get_cpu_var(lru_add_active_pvecs);
193
194 page_cache_get(page);
195 if (!pagevec_add(pvec, page))
196 __pagevec_lru_add_active(pvec);
197 put_cpu_var(lru_add_active_pvecs);
198}
199
Andrew Morton80bfed92006-01-06 00:11:14 -0800200static void __lru_add_drain(int cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700201{
Andrew Morton80bfed92006-01-06 00:11:14 -0800202 struct pagevec *pvec = &per_cpu(lru_add_pvecs, cpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700203
Andrew Morton80bfed92006-01-06 00:11:14 -0800204 /* CPU is dead, so no locking needed. */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205 if (pagevec_count(pvec))
206 __pagevec_lru_add(pvec);
Andrew Morton80bfed92006-01-06 00:11:14 -0800207 pvec = &per_cpu(lru_add_active_pvecs, cpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 if (pagevec_count(pvec))
209 __pagevec_lru_add_active(pvec);
Andrew Morton80bfed92006-01-06 00:11:14 -0800210}
211
212void lru_add_drain(void)
213{
214 __lru_add_drain(get_cpu());
215 put_cpu();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700216}
217
Nick Piggin053837f2006-01-18 17:42:27 -0800218#ifdef CONFIG_NUMA
David Howellsc4028952006-11-22 14:57:56 +0000219static void lru_add_drain_per_cpu(struct work_struct *dummy)
Nick Piggin053837f2006-01-18 17:42:27 -0800220{
221 lru_add_drain();
222}
223
224/*
225 * Returns 0 for success
226 */
227int lru_add_drain_all(void)
228{
David Howellsc4028952006-11-22 14:57:56 +0000229 return schedule_on_each_cpu(lru_add_drain_per_cpu);
Nick Piggin053837f2006-01-18 17:42:27 -0800230}
231
232#else
233
234/*
235 * Returns 0 for success
236 */
237int lru_add_drain_all(void)
238{
239 lru_add_drain();
240 return 0;
241}
242#endif
243
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700245 * Batched page_cache_release(). Decrement the reference count on all the
246 * passed pages. If it fell to zero then remove the page from the LRU and
247 * free it.
248 *
249 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
250 * for the remainder of the operation.
251 *
252 * The locking in this function is against shrink_cache(): we recheck the
253 * page count inside the lock to see whether shrink_cache grabbed the page
254 * via the LRU. If it did, give up: shrink_cache will free it.
255 */
256void release_pages(struct page **pages, int nr, int cold)
257{
258 int i;
259 struct pagevec pages_to_free;
260 struct zone *zone = NULL;
261
262 pagevec_init(&pages_to_free, cold);
263 for (i = 0; i < nr; i++) {
264 struct page *page = pages[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700265
Nick Piggin8519fb32006-02-07 12:58:52 -0800266 if (unlikely(PageCompound(page))) {
267 if (zone) {
268 spin_unlock_irq(&zone->lru_lock);
269 zone = NULL;
270 }
271 put_compound_page(page);
272 continue;
273 }
274
Nick Pigginb5810032005-10-29 18:16:12 -0700275 if (!put_page_testzero(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700276 continue;
277
Nick Piggin46453a62006-03-22 00:07:58 -0800278 if (PageLRU(page)) {
279 struct zone *pagezone = page_zone(page);
280 if (pagezone != zone) {
281 if (zone)
282 spin_unlock_irq(&zone->lru_lock);
283 zone = pagezone;
284 spin_lock_irq(&zone->lru_lock);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700285 }
Nick Piggin725d7042006-09-25 23:30:55 -0700286 VM_BUG_ON(!PageLRU(page));
Nick Piggin67453912006-03-22 00:08:00 -0800287 __ClearPageLRU(page);
Nick Piggin46453a62006-03-22 00:07:58 -0800288 del_page_from_lru(zone, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700289 }
Nick Piggin46453a62006-03-22 00:07:58 -0800290
291 if (!pagevec_add(&pages_to_free, page)) {
292 if (zone) {
293 spin_unlock_irq(&zone->lru_lock);
294 zone = NULL;
295 }
296 __pagevec_free(&pages_to_free);
297 pagevec_reinit(&pages_to_free);
298 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299 }
300 if (zone)
301 spin_unlock_irq(&zone->lru_lock);
302
303 pagevec_free(&pages_to_free);
304}
305
306/*
307 * The pages which we're about to release may be in the deferred lru-addition
308 * queues. That would prevent them from really being freed right now. That's
309 * OK from a correctness point of view but is inefficient - those pages may be
310 * cache-warm and we want to give them back to the page allocator ASAP.
311 *
312 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
313 * and __pagevec_lru_add_active() call release_pages() directly to avoid
314 * mutual recursion.
315 */
316void __pagevec_release(struct pagevec *pvec)
317{
318 lru_add_drain();
319 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
320 pagevec_reinit(pvec);
321}
322
Steve French7f285702005-11-01 10:22:55 -0800323EXPORT_SYMBOL(__pagevec_release);
324
Linus Torvalds1da177e2005-04-16 15:20:36 -0700325/*
326 * pagevec_release() for pages which are known to not be on the LRU
327 *
328 * This function reinitialises the caller's pagevec.
329 */
330void __pagevec_release_nonlru(struct pagevec *pvec)
331{
332 int i;
333 struct pagevec pages_to_free;
334
335 pagevec_init(&pages_to_free, pvec->cold);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700336 for (i = 0; i < pagevec_count(pvec); i++) {
337 struct page *page = pvec->pages[i];
338
Nick Piggin725d7042006-09-25 23:30:55 -0700339 VM_BUG_ON(PageLRU(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700340 if (put_page_testzero(page))
341 pagevec_add(&pages_to_free, page);
342 }
343 pagevec_free(&pages_to_free);
344 pagevec_reinit(pvec);
345}
346
347/*
348 * Add the passed pages to the LRU, then drop the caller's refcount
349 * on them. Reinitialises the caller's pagevec.
350 */
351void __pagevec_lru_add(struct pagevec *pvec)
352{
353 int i;
354 struct zone *zone = NULL;
355
356 for (i = 0; i < pagevec_count(pvec); i++) {
357 struct page *page = pvec->pages[i];
358 struct zone *pagezone = page_zone(page);
359
360 if (pagezone != zone) {
361 if (zone)
362 spin_unlock_irq(&zone->lru_lock);
363 zone = pagezone;
364 spin_lock_irq(&zone->lru_lock);
365 }
Nick Piggin725d7042006-09-25 23:30:55 -0700366 VM_BUG_ON(PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -0800367 SetPageLRU(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700368 add_page_to_inactive_list(zone, page);
369 }
370 if (zone)
371 spin_unlock_irq(&zone->lru_lock);
372 release_pages(pvec->pages, pvec->nr, pvec->cold);
373 pagevec_reinit(pvec);
374}
375
376EXPORT_SYMBOL(__pagevec_lru_add);
377
378void __pagevec_lru_add_active(struct pagevec *pvec)
379{
380 int i;
381 struct zone *zone = NULL;
382
383 for (i = 0; i < pagevec_count(pvec); i++) {
384 struct page *page = pvec->pages[i];
385 struct zone *pagezone = page_zone(page);
386
387 if (pagezone != zone) {
388 if (zone)
389 spin_unlock_irq(&zone->lru_lock);
390 zone = pagezone;
391 spin_lock_irq(&zone->lru_lock);
392 }
Nick Piggin725d7042006-09-25 23:30:55 -0700393 VM_BUG_ON(PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -0800394 SetPageLRU(page);
Nick Piggin725d7042006-09-25 23:30:55 -0700395 VM_BUG_ON(PageActive(page));
Nick Piggin4c84cac2006-03-22 00:08:00 -0800396 SetPageActive(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700397 add_page_to_active_list(zone, page);
398 }
399 if (zone)
400 spin_unlock_irq(&zone->lru_lock);
401 release_pages(pvec->pages, pvec->nr, pvec->cold);
402 pagevec_reinit(pvec);
403}
404
405/*
406 * Try to drop buffers from the pages in a pagevec
407 */
408void pagevec_strip(struct pagevec *pvec)
409{
410 int i;
411
412 for (i = 0; i < pagevec_count(pvec); i++) {
413 struct page *page = pvec->pages[i];
414
415 if (PagePrivate(page) && !TestSetPageLocked(page)) {
Christoph Lameter5b40dc72006-03-16 23:04:07 -0800416 if (PagePrivate(page))
417 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700418 unlock_page(page);
419 }
420 }
421}
422
423/**
424 * pagevec_lookup - gang pagecache lookup
425 * @pvec: Where the resulting pages are placed
426 * @mapping: The address_space to search
427 * @start: The starting page index
428 * @nr_pages: The maximum number of pages
429 *
430 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
431 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
432 * reference against the pages in @pvec.
433 *
434 * The search returns a group of mapping-contiguous pages with ascending
435 * indexes. There may be holes in the indices due to not-present pages.
436 *
437 * pagevec_lookup() returns the number of pages which were found.
438 */
439unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
440 pgoff_t start, unsigned nr_pages)
441{
442 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
443 return pagevec_count(pvec);
444}
445
Christoph Hellwig78539fd2006-01-11 20:47:41 +1100446EXPORT_SYMBOL(pagevec_lookup);
447
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
449 pgoff_t *index, int tag, unsigned nr_pages)
450{
451 pvec->nr = find_get_pages_tag(mapping, index, tag,
452 nr_pages, pvec->pages);
453 return pagevec_count(pvec);
454}
455
Steve French7f285702005-11-01 10:22:55 -0800456EXPORT_SYMBOL(pagevec_lookup_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700457
458#ifdef CONFIG_SMP
459/*
460 * We tolerate a little inaccuracy to avoid ping-ponging the counter between
461 * CPUs
462 */
463#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
464
465static DEFINE_PER_CPU(long, committed_space) = 0;
466
467void vm_acct_memory(long pages)
468{
469 long *local;
470
471 preempt_disable();
472 local = &__get_cpu_var(committed_space);
473 *local += pages;
474 if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) {
475 atomic_add(*local, &vm_committed_space);
476 *local = 0;
477 }
478 preempt_enable();
479}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700480
481#ifdef CONFIG_HOTPLUG_CPU
Linus Torvalds1da177e2005-04-16 15:20:36 -0700482
483/* Drop the CPU's cached committed space back into the central pool. */
484static int cpu_swap_callback(struct notifier_block *nfb,
485 unsigned long action,
486 void *hcpu)
487{
488 long *committed;
489
490 committed = &per_cpu(committed_space, (long)hcpu);
491 if (action == CPU_DEAD) {
492 atomic_add(*committed, &vm_committed_space);
493 *committed = 0;
Andrew Morton80bfed92006-01-06 00:11:14 -0800494 __lru_add_drain((long)hcpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700495 }
496 return NOTIFY_OK;
497}
498#endif /* CONFIG_HOTPLUG_CPU */
499#endif /* CONFIG_SMP */
500
Linus Torvalds1da177e2005-04-16 15:20:36 -0700501/*
502 * Perform any setup for the swap system
503 */
504void __init swap_setup(void)
505{
506 unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
507
508 /* Use a smaller cluster for small-memory machines */
509 if (megs < 16)
510 page_cluster = 2;
511 else
512 page_cluster = 3;
513 /*
514 * Right now other parts of the system means that we
515 * _really_ don't want to cluster much more
516 */
Ingo Molnar02316062006-12-06 20:38:17 -0800517#ifdef CONFIG_HOTPLUG_CPU
Linus Torvalds1da177e2005-04-16 15:20:36 -0700518 hotcpu_notifier(cpu_swap_callback, 0);
Ingo Molnar02316062006-12-06 20:38:17 -0800519#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700520}