blob: 8adb9feb61e10b7385e01d3410d8cb0f0a4807e1 [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/*
Simon Arlott183ff222007-10-20 01:27:18 +02008 * This file contains the default values for the operation of the
Linus Torvalds1da177e2005-04-16 15:20:36 -07009 * 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() */
Linus Torvalds1da177e2005-04-16 15:20:36 -070027#include <linux/percpu_counter.h>
28#include <linux/percpu.h>
29#include <linux/cpu.h>
30#include <linux/notifier.h>
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -070031#include <linux/backing-dev.h>
Balbir Singh66e17072008-02-07 00:13:56 -080032#include <linux/memcontrol.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070033
Lee Schermerhorn64d65192008-10-18 20:26:52 -070034#include "internal.h"
35
Linus Torvalds1da177e2005-04-16 15:20:36 -070036/* How many pages do we try to swap or page in/out together? */
37int page_cluster;
38
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -070039static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
Vegard Nossumf84f95042008-07-23 21:28:14 -070040static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -070041
Adrian Bunkb2213852006-09-25 23:31:02 -070042/*
43 * This path almost never happens for VM activity - pages are normally
44 * freed via pagevecs. But it gets used by networking.
45 */
Harvey Harrison920c7a52008-02-04 22:29:26 -080046static void __page_cache_release(struct page *page)
Adrian Bunkb2213852006-09-25 23:31:02 -070047{
48 if (PageLRU(page)) {
49 unsigned long flags;
50 struct zone *zone = page_zone(page);
51
52 spin_lock_irqsave(&zone->lru_lock, flags);
53 VM_BUG_ON(!PageLRU(page));
54 __ClearPageLRU(page);
55 del_page_from_lru(zone, page);
56 spin_unlock_irqrestore(&zone->lru_lock, flags);
57 }
58 free_hot_page(page);
59}
60
Nick Piggin8519fb32006-02-07 12:58:52 -080061static void put_compound_page(struct page *page)
62{
Christoph Lameterd85f3382007-05-06 14:49:39 -070063 page = compound_head(page);
Nick Piggin8519fb32006-02-07 12:58:52 -080064 if (put_page_testzero(page)) {
Andy Whitcroft33f2ef82006-12-06 20:33:32 -080065 compound_page_dtor *dtor;
Nick Piggin8519fb32006-02-07 12:58:52 -080066
Andy Whitcroft33f2ef82006-12-06 20:33:32 -080067 dtor = get_compound_page_dtor(page);
Nick Piggin8519fb32006-02-07 12:58:52 -080068 (*dtor)(page);
69 }
70}
71
Linus Torvalds1da177e2005-04-16 15:20:36 -070072void put_page(struct page *page)
73{
Nick Piggin8519fb32006-02-07 12:58:52 -080074 if (unlikely(PageCompound(page)))
75 put_compound_page(page);
76 else if (put_page_testzero(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -070077 __page_cache_release(page);
78}
79EXPORT_SYMBOL(put_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -070080
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -070081/**
Randy Dunlap76824862008-03-19 17:00:40 -070082 * put_pages_list() - release a list of pages
83 * @pages: list of pages threaded on page->lru
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -070084 *
85 * Release a list of pages which are strung together on page.lru. Currently
86 * used by read_cache_pages() and related error recovery code.
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -070087 */
88void put_pages_list(struct list_head *pages)
89{
90 while (!list_empty(pages)) {
91 struct page *victim;
92
93 victim = list_entry(pages->prev, struct page, lru);
94 list_del(&victim->lru);
95 page_cache_release(victim);
96 }
97}
98EXPORT_SYMBOL(put_pages_list);
99
Linus Torvalds1da177e2005-04-16 15:20:36 -0700100/*
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700101 * pagevec_move_tail() must be called with IRQ disabled.
102 * Otherwise this may cause nasty races.
103 */
104static void pagevec_move_tail(struct pagevec *pvec)
105{
106 int i;
107 int pgmoved = 0;
108 struct zone *zone = NULL;
109
110 for (i = 0; i < pagevec_count(pvec); i++) {
111 struct page *page = pvec->pages[i];
112 struct zone *pagezone = page_zone(page);
113
114 if (pagezone != zone) {
115 if (zone)
116 spin_unlock(&zone->lru_lock);
117 zone = pagezone;
118 spin_lock(&zone->lru_lock);
119 }
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700120 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700121 int lru = page_is_file_cache(page);
122 list_move_tail(&page->lru, &zone->lru[lru].list);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700123 pgmoved++;
124 }
125 }
126 if (zone)
127 spin_unlock(&zone->lru_lock);
128 __count_vm_events(PGROTATED, pgmoved);
129 release_pages(pvec->pages, pvec->nr, pvec->cold);
130 pagevec_reinit(pvec);
131}
132
133/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700134 * Writeback is about to end against a page which has been marked for immediate
135 * reclaim. If it still appears to be reclaimable, move it to the tail of the
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700136 * inactive list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700137 */
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700138void rotate_reclaimable_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700139{
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700140 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700141 !PageUnevictable(page) && PageLRU(page)) {
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700142 struct pagevec *pvec;
143 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700144
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700145 page_cache_get(page);
146 local_irq_save(flags);
147 pvec = &__get_cpu_var(lru_rotate_pvecs);
148 if (!pagevec_add(pvec, page))
149 pagevec_move_tail(pvec);
150 local_irq_restore(flags);
151 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700152}
153
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800154static void update_page_reclaim_stat(struct zone *zone, struct page *page,
155 int file, int rotated)
156{
157 struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat;
158 struct zone_reclaim_stat *memcg_reclaim_stat;
159
160 memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page);
161
162 reclaim_stat->recent_scanned[file]++;
163 if (rotated)
164 reclaim_stat->recent_rotated[file]++;
165
166 if (!memcg_reclaim_stat)
167 return;
168
169 memcg_reclaim_stat->recent_scanned[file]++;
170 if (rotated)
171 memcg_reclaim_stat->recent_rotated[file]++;
172}
173
Linus Torvalds1da177e2005-04-16 15:20:36 -0700174/*
175 * FIXME: speed this up?
176 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800177void activate_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700178{
179 struct zone *zone = page_zone(page);
180
181 spin_lock_irq(&zone->lru_lock);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700182 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700183 int file = page_is_file_cache(page);
184 int lru = LRU_BASE + file;
185 del_page_from_lru_list(zone, page, lru);
186
Linus Torvalds1da177e2005-04-16 15:20:36 -0700187 SetPageActive(page);
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700188 lru += LRU_ACTIVE;
189 add_page_to_lru_list(zone, page, lru);
Christoph Lameterf8891e52006-06-30 01:55:45 -0700190 __count_vm_event(PGACTIVATE);
Rik van Riel4f98a2f2008-10-18 20:26:32 -0700191
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800192 update_page_reclaim_stat(zone, page, !!file, 1);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700193 }
194 spin_unlock_irq(&zone->lru_lock);
195}
196
197/*
198 * Mark a page as having seen activity.
199 *
200 * inactive,unreferenced -> inactive,referenced
201 * inactive,referenced -> active,unreferenced
202 * active,unreferenced -> active,referenced
203 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800204void mark_page_accessed(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700205{
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700206 if (!PageActive(page) && !PageUnevictable(page) &&
207 PageReferenced(page) && PageLRU(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700208 activate_page(page);
209 ClearPageReferenced(page);
210 } else if (!PageReferenced(page)) {
211 SetPageReferenced(page);
212 }
213}
214
215EXPORT_SYMBOL(mark_page_accessed);
216
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700217void __lru_cache_add(struct page *page, enum lru_list lru)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700218{
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700219 struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700220
221 page_cache_get(page);
222 if (!pagevec_add(pvec, page))
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700223 ____pagevec_lru_add(pvec, lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700224 put_cpu_var(lru_add_pvecs);
225}
226
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700227/**
228 * lru_cache_add_lru - add a page to a page list
229 * @page: the page to be added to the LRU.
230 * @lru: the LRU list to which the page is added.
231 */
232void lru_cache_add_lru(struct page *page, enum lru_list lru)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700233{
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700234 if (PageActive(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700235 VM_BUG_ON(PageUnevictable(page));
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700236 ClearPageActive(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700237 } else if (PageUnevictable(page)) {
238 VM_BUG_ON(PageActive(page));
239 ClearPageUnevictable(page);
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700240 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700241
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700242 VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page));
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700243 __lru_cache_add(page, lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700244}
245
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700246/**
247 * add_page_to_unevictable_list - add a page to the unevictable list
248 * @page: the page to be added to the unevictable list
249 *
250 * Add page directly to its zone's unevictable list. To avoid races with
251 * tasks that might be making the page evictable, through eg. munlock,
252 * munmap or exit, while it's not on the lru, we want to add the page
253 * while it's locked or otherwise "invisible" to other tasks. This is
254 * difficult to do when using the pagevec cache, so bypass that.
255 */
256void add_page_to_unevictable_list(struct page *page)
257{
258 struct zone *zone = page_zone(page);
259
260 spin_lock_irq(&zone->lru_lock);
261 SetPageUnevictable(page);
262 SetPageLRU(page);
263 add_page_to_lru_list(zone, page, LRU_UNEVICTABLE);
264 spin_unlock_irq(&zone->lru_lock);
265}
266
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700267/*
268 * Drain pages out of the cpu's pagevecs.
269 * Either "cpu" is the current CPU, and preemption has already been
270 * disabled; or "cpu" is being hot-unplugged, and is already dead.
271 */
272static void drain_cpu_pagevecs(int cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700273{
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700274 struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700275 struct pagevec *pvec;
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700276 int lru;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700277
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700278 for_each_lru(lru) {
279 pvec = &pvecs[lru - LRU_BASE];
280 if (pagevec_count(pvec))
281 ____pagevec_lru_add(pvec, lru);
282 }
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700283
284 pvec = &per_cpu(lru_rotate_pvecs, cpu);
285 if (pagevec_count(pvec)) {
286 unsigned long flags;
287
288 /* No harm done if a racing interrupt already did this */
289 local_irq_save(flags);
290 pagevec_move_tail(pvec);
291 local_irq_restore(flags);
292 }
Andrew Morton80bfed92006-01-06 00:11:14 -0800293}
294
295void lru_add_drain(void)
296{
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700297 drain_cpu_pagevecs(get_cpu());
Andrew Morton80bfed92006-01-06 00:11:14 -0800298 put_cpu();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700299}
300
David Howellsc4028952006-11-22 14:57:56 +0000301static void lru_add_drain_per_cpu(struct work_struct *dummy)
Nick Piggin053837f2006-01-18 17:42:27 -0800302{
303 lru_add_drain();
304}
305
306/*
307 * Returns 0 for success
308 */
309int lru_add_drain_all(void)
310{
David Howellsc4028952006-11-22 14:57:56 +0000311 return schedule_on_each_cpu(lru_add_drain_per_cpu);
Nick Piggin053837f2006-01-18 17:42:27 -0800312}
313
Linus Torvalds1da177e2005-04-16 15:20:36 -0700314/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700315 * Batched page_cache_release(). Decrement the reference count on all the
316 * passed pages. If it fell to zero then remove the page from the LRU and
317 * free it.
318 *
319 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
320 * for the remainder of the operation.
321 *
Fernando Luis Vazquez Caoab33dc02008-07-29 22:33:40 -0700322 * The locking in this function is against shrink_inactive_list(): we recheck
323 * the page count inside the lock to see whether shrink_inactive_list()
324 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
325 * will free it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700326 */
327void release_pages(struct page **pages, int nr, int cold)
328{
329 int i;
330 struct pagevec pages_to_free;
331 struct zone *zone = NULL;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700332 unsigned long uninitialized_var(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700333
334 pagevec_init(&pages_to_free, cold);
335 for (i = 0; i < nr; i++) {
336 struct page *page = pages[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700337
Nick Piggin8519fb32006-02-07 12:58:52 -0800338 if (unlikely(PageCompound(page))) {
339 if (zone) {
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700340 spin_unlock_irqrestore(&zone->lru_lock, flags);
Nick Piggin8519fb32006-02-07 12:58:52 -0800341 zone = NULL;
342 }
343 put_compound_page(page);
344 continue;
345 }
346
Nick Pigginb5810032005-10-29 18:16:12 -0700347 if (!put_page_testzero(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700348 continue;
349
Nick Piggin46453a62006-03-22 00:07:58 -0800350 if (PageLRU(page)) {
351 struct zone *pagezone = page_zone(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700352
Nick Piggin46453a62006-03-22 00:07:58 -0800353 if (pagezone != zone) {
354 if (zone)
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700355 spin_unlock_irqrestore(&zone->lru_lock,
356 flags);
Nick Piggin46453a62006-03-22 00:07:58 -0800357 zone = pagezone;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700358 spin_lock_irqsave(&zone->lru_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700359 }
Nick Piggin725d7042006-09-25 23:30:55 -0700360 VM_BUG_ON(!PageLRU(page));
Nick Piggin67453912006-03-22 00:08:00 -0800361 __ClearPageLRU(page);
Nick Piggin46453a62006-03-22 00:07:58 -0800362 del_page_from_lru(zone, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700363 }
Nick Piggin46453a62006-03-22 00:07:58 -0800364
365 if (!pagevec_add(&pages_to_free, page)) {
366 if (zone) {
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700367 spin_unlock_irqrestore(&zone->lru_lock, flags);
Nick Piggin46453a62006-03-22 00:07:58 -0800368 zone = NULL;
369 }
370 __pagevec_free(&pages_to_free);
371 pagevec_reinit(&pages_to_free);
372 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700373 }
374 if (zone)
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700375 spin_unlock_irqrestore(&zone->lru_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700376
377 pagevec_free(&pages_to_free);
378}
379
380/*
381 * The pages which we're about to release may be in the deferred lru-addition
382 * queues. That would prevent them from really being freed right now. That's
383 * OK from a correctness point of view but is inefficient - those pages may be
384 * cache-warm and we want to give them back to the page allocator ASAP.
385 *
386 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
387 * and __pagevec_lru_add_active() call release_pages() directly to avoid
388 * mutual recursion.
389 */
390void __pagevec_release(struct pagevec *pvec)
391{
392 lru_add_drain();
393 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
394 pagevec_reinit(pvec);
395}
396
Steve French7f285702005-11-01 10:22:55 -0800397EXPORT_SYMBOL(__pagevec_release);
398
Linus Torvalds1da177e2005-04-16 15:20:36 -0700399/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700400 * Add the passed pages to the LRU, then drop the caller's refcount
401 * on them. Reinitialises the caller's pagevec.
402 */
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700403void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700404{
405 int i;
406 struct zone *zone = NULL;
KOSAKI Motohiro6e901572009-01-07 18:08:15 -0800407
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700408 VM_BUG_ON(is_unevictable_lru(lru));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700409
410 for (i = 0; i < pagevec_count(pvec); i++) {
411 struct page *page = pvec->pages[i];
412 struct zone *pagezone = page_zone(page);
Rik van Riel9ff473b2008-12-02 10:31:52 -0800413 int file;
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800414 int active;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700415
416 if (pagezone != zone) {
417 if (zone)
418 spin_unlock_irq(&zone->lru_lock);
419 zone = pagezone;
420 spin_lock_irq(&zone->lru_lock);
421 }
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700422 VM_BUG_ON(PageActive(page));
423 VM_BUG_ON(PageUnevictable(page));
Nick Piggin725d7042006-09-25 23:30:55 -0700424 VM_BUG_ON(PageLRU(page));
Nick Piggin8d438f92006-03-22 00:07:59 -0800425 SetPageLRU(page);
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800426 active = is_active_lru(lru);
Rik van Riel9ff473b2008-12-02 10:31:52 -0800427 file = is_file_lru(lru);
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800428 if (active)
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700429 SetPageActive(page);
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800430 update_page_reclaim_stat(zone, page, file, active);
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700431 add_page_to_lru_list(zone, page, lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700432 }
433 if (zone)
434 spin_unlock_irq(&zone->lru_lock);
435 release_pages(pvec->pages, pvec->nr, pvec->cold);
436 pagevec_reinit(pvec);
437}
438
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700439EXPORT_SYMBOL(____pagevec_lru_add);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700440
441/*
442 * Try to drop buffers from the pages in a pagevec
443 */
444void pagevec_strip(struct pagevec *pvec)
445{
446 int i;
447
448 for (i = 0; i < pagevec_count(pvec); i++) {
449 struct page *page = pvec->pages[i];
450
Nick Piggin529ae9a2008-08-02 12:01:03 +0200451 if (PagePrivate(page) && trylock_page(page)) {
Christoph Lameter5b40dc72006-03-16 23:04:07 -0800452 if (PagePrivate(page))
453 try_to_release_page(page, 0);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700454 unlock_page(page);
455 }
456 }
457}
458
459/**
Rik van Riel68a223942008-10-18 20:26:23 -0700460 * pagevec_swap_free - try to free swap space from the pages in a pagevec
461 * @pvec: pagevec with swapcache pages to free the swap space of
462 *
463 * The caller needs to hold an extra reference to each page and
464 * not hold the page lock on the pages. This function uses a
465 * trylock on the page lock so it may not always free the swap
466 * space associated with a page.
467 */
468void pagevec_swap_free(struct pagevec *pvec)
469{
470 int i;
471
472 for (i = 0; i < pagevec_count(pvec); i++) {
473 struct page *page = pvec->pages[i];
474
475 if (PageSwapCache(page) && trylock_page(page)) {
Hugh Dickinsa2c43ee2009-01-06 14:39:36 -0800476 try_to_free_swap(page);
Rik van Riel68a223942008-10-18 20:26:23 -0700477 unlock_page(page);
478 }
479 }
480}
481
482/**
Linus Torvalds1da177e2005-04-16 15:20:36 -0700483 * pagevec_lookup - gang pagecache lookup
484 * @pvec: Where the resulting pages are placed
485 * @mapping: The address_space to search
486 * @start: The starting page index
487 * @nr_pages: The maximum number of pages
488 *
489 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
490 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
491 * reference against the pages in @pvec.
492 *
493 * The search returns a group of mapping-contiguous pages with ascending
494 * indexes. There may be holes in the indices due to not-present pages.
495 *
496 * pagevec_lookup() returns the number of pages which were found.
497 */
498unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
499 pgoff_t start, unsigned nr_pages)
500{
501 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
502 return pagevec_count(pvec);
503}
504
Christoph Hellwig78539fd2006-01-11 20:47:41 +1100505EXPORT_SYMBOL(pagevec_lookup);
506
Linus Torvalds1da177e2005-04-16 15:20:36 -0700507unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
508 pgoff_t *index, int tag, unsigned nr_pages)
509{
510 pvec->nr = find_get_pages_tag(mapping, index, tag,
511 nr_pages, pvec->pages);
512 return pagevec_count(pvec);
513}
514
Steve French7f285702005-11-01 10:22:55 -0800515EXPORT_SYMBOL(pagevec_lookup_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700516
517#ifdef CONFIG_SMP
518/*
519 * We tolerate a little inaccuracy to avoid ping-ponging the counter between
520 * CPUs
521 */
522#define ACCT_THRESHOLD max(16, NR_CPUS * 2)
523
Vegard Nossumf84f95042008-07-23 21:28:14 -0700524static DEFINE_PER_CPU(long, committed_space);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700525
526void vm_acct_memory(long pages)
527{
528 long *local;
529
530 preempt_disable();
531 local = &__get_cpu_var(committed_space);
532 *local += pages;
533 if (*local > ACCT_THRESHOLD || *local < -ACCT_THRESHOLD) {
Alan Cox80119ef2008-05-23 13:04:31 -0700534 atomic_long_add(*local, &vm_committed_space);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700535 *local = 0;
536 }
537 preempt_enable();
538}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700539
540#ifdef CONFIG_HOTPLUG_CPU
Linus Torvalds1da177e2005-04-16 15:20:36 -0700541
542/* Drop the CPU's cached committed space back into the central pool. */
543static int cpu_swap_callback(struct notifier_block *nfb,
544 unsigned long action,
545 void *hcpu)
546{
547 long *committed;
548
549 committed = &per_cpu(committed_space, (long)hcpu);
Rafael J. Wysocki8bb78442007-05-09 02:35:10 -0700550 if (action == CPU_DEAD || action == CPU_DEAD_FROZEN) {
Alan Cox80119ef2008-05-23 13:04:31 -0700551 atomic_long_add(*committed, &vm_committed_space);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700552 *committed = 0;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700553 drain_cpu_pagevecs((long)hcpu);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700554 }
555 return NOTIFY_OK;
556}
557#endif /* CONFIG_HOTPLUG_CPU */
558#endif /* CONFIG_SMP */
559
Linus Torvalds1da177e2005-04-16 15:20:36 -0700560/*
561 * Perform any setup for the swap system
562 */
563void __init swap_setup(void)
564{
565 unsigned long megs = num_physpages >> (20 - PAGE_SHIFT);
566
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700567#ifdef CONFIG_SWAP
568 bdi_init(swapper_space.backing_dev_info);
569#endif
570
Linus Torvalds1da177e2005-04-16 15:20:36 -0700571 /* Use a smaller cluster for small-memory machines */
572 if (megs < 16)
573 page_cluster = 2;
574 else
575 page_cluster = 3;
576 /*
577 * Right now other parts of the system means that we
578 * _really_ don't want to cluster much more
579 */
Ingo Molnar02316062006-12-06 20:38:17 -0800580#ifdef CONFIG_HOTPLUG_CPU
Linus Torvalds1da177e2005-04-16 15:20:36 -0700581 hotcpu_notifier(cpu_swap_callback, 0);
Ingo Molnar02316062006-12-06 20:38:17 -0800582#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700583}