blob: dfd7d71d68418023b592c09a7d18c7a3ac4c5843 [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>
Paul Gortmakerb95f1b312011-10-16 02:01:52 -040024#include <linux/export.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070025#include <linux/mm_inline.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070026#include <linux/percpu_counter.h>
27#include <linux/percpu.h>
28#include <linux/cpu.h>
29#include <linux/notifier.h>
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -070030#include <linux/backing-dev.h>
Balbir Singh66e17072008-02-07 00:13:56 -080031#include <linux/memcontrol.h>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090032#include <linux/gfp.h>
Kent Overstreeta27bb332013-05-07 16:19:08 -070033#include <linux/uio.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070034
Lee Schermerhorn64d65192008-10-18 20:26:52 -070035#include "internal.h"
36
Linus Torvalds1da177e2005-04-16 15:20:36 -070037/* How many pages do we try to swap or page in/out together? */
38int page_cluster;
39
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -070040static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
Vegard Nossumf84f95042008-07-23 21:28:14 -070041static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
Minchan Kim31560182011-03-22 16:32:52 -070042static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -070043
Adrian Bunkb2213852006-09-25 23:31:02 -070044/*
45 * This path almost never happens for VM activity - pages are normally
46 * freed via pagevecs. But it gets used by networking.
47 */
Harvey Harrison920c7a52008-02-04 22:29:26 -080048static void __page_cache_release(struct page *page)
Adrian Bunkb2213852006-09-25 23:31:02 -070049{
50 if (PageLRU(page)) {
Adrian Bunkb2213852006-09-25 23:31:02 -070051 struct zone *zone = page_zone(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -070052 struct lruvec *lruvec;
53 unsigned long flags;
Adrian Bunkb2213852006-09-25 23:31:02 -070054
55 spin_lock_irqsave(&zone->lru_lock, flags);
Hugh Dickinsfa9add62012-05-29 15:07:09 -070056 lruvec = mem_cgroup_page_lruvec(page, zone);
Adrian Bunkb2213852006-09-25 23:31:02 -070057 VM_BUG_ON(!PageLRU(page));
58 __ClearPageLRU(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -070059 del_page_from_lru_list(page, lruvec, page_off_lru(page));
Adrian Bunkb2213852006-09-25 23:31:02 -070060 spin_unlock_irqrestore(&zone->lru_lock, flags);
61 }
Andrea Arcangeli91807062011-01-13 15:46:32 -080062}
63
64static void __put_single_page(struct page *page)
65{
66 __page_cache_release(page);
Li Hongfc916682010-03-05 13:41:54 -080067 free_hot_cold_page(page, 0);
Adrian Bunkb2213852006-09-25 23:31:02 -070068}
69
Andrea Arcangeli91807062011-01-13 15:46:32 -080070static void __put_compound_page(struct page *page)
71{
72 compound_page_dtor *dtor;
73
74 __page_cache_release(page);
75 dtor = get_compound_page_dtor(page);
76 (*dtor)(page);
77}
78
Nick Piggin8519fb32006-02-07 12:58:52 -080079static void put_compound_page(struct page *page)
80{
Andrea Arcangeli91807062011-01-13 15:46:32 -080081 if (unlikely(PageTail(page))) {
82 /* __split_huge_page_refcount can run under us */
Andrea Arcangeli70b50f92011-11-02 13:36:59 -070083 struct page *page_head = compound_trans_head(page);
84
85 if (likely(page != page_head &&
86 get_page_unless_zero(page_head))) {
Andrea Arcangeli91807062011-01-13 15:46:32 -080087 unsigned long flags;
Pravin B Shelar5bf5f032012-05-29 15:06:49 -070088
89 /*
90 * THP can not break up slab pages so avoid taking
91 * compound_lock(). Slab performs non-atomic bit ops
92 * on page->flags for better performance. In particular
93 * slab_unlock() in slub used to be a hot path. It is
94 * still hot on arches that do not support
95 * this_cpu_cmpxchg_double().
96 */
97 if (PageSlab(page_head)) {
98 if (PageTail(page)) {
99 if (put_page_testzero(page_head))
100 VM_BUG_ON(1);
101
102 atomic_dec(&page->_mapcount);
103 goto skip_lock_tail;
104 } else
105 goto skip_lock;
106 }
Andrea Arcangeli91807062011-01-13 15:46:32 -0800107 /*
Andrea Arcangeli70b50f92011-11-02 13:36:59 -0700108 * page_head wasn't a dangling pointer but it
109 * may not be a head page anymore by the time
110 * we obtain the lock. That is ok as long as it
111 * can't be freed from under us.
Andrea Arcangeli91807062011-01-13 15:46:32 -0800112 */
Andrea Arcangeli91807062011-01-13 15:46:32 -0800113 flags = compound_lock_irqsave(page_head);
114 if (unlikely(!PageTail(page))) {
115 /* __split_huge_page_refcount run before us */
116 compound_unlock_irqrestore(page_head, flags);
Pravin B Shelar5bf5f032012-05-29 15:06:49 -0700117skip_lock:
Andrea Arcangeli91807062011-01-13 15:46:32 -0800118 if (put_page_testzero(page_head))
119 __put_single_page(page_head);
Pravin B Shelar5bf5f032012-05-29 15:06:49 -0700120out_put_single:
Andrea Arcangeli91807062011-01-13 15:46:32 -0800121 if (put_page_testzero(page))
122 __put_single_page(page);
123 return;
124 }
125 VM_BUG_ON(page_head != page->first_page);
126 /*
127 * We can release the refcount taken by
Andrea Arcangeli70b50f92011-11-02 13:36:59 -0700128 * get_page_unless_zero() now that
129 * __split_huge_page_refcount() is blocked on
130 * the compound_lock.
Andrea Arcangeli91807062011-01-13 15:46:32 -0800131 */
132 if (put_page_testzero(page_head))
133 VM_BUG_ON(1);
134 /* __split_huge_page_refcount will wait now */
Andrea Arcangeli70b50f92011-11-02 13:36:59 -0700135 VM_BUG_ON(page_mapcount(page) <= 0);
136 atomic_dec(&page->_mapcount);
Andrea Arcangeli91807062011-01-13 15:46:32 -0800137 VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
Andrea Arcangeli70b50f92011-11-02 13:36:59 -0700138 VM_BUG_ON(atomic_read(&page->_count) != 0);
Andrea Arcangeli91807062011-01-13 15:46:32 -0800139 compound_unlock_irqrestore(page_head, flags);
Pravin B Shelar5bf5f032012-05-29 15:06:49 -0700140
141skip_lock_tail:
Andrea Arcangelia95a82e2011-01-13 15:46:33 -0800142 if (put_page_testzero(page_head)) {
143 if (PageHead(page_head))
144 __put_compound_page(page_head);
145 else
146 __put_single_page(page_head);
147 }
Andrea Arcangeli91807062011-01-13 15:46:32 -0800148 } else {
149 /* page_head is a dangling pointer */
150 VM_BUG_ON(PageTail(page));
151 goto out_put_single;
152 }
153 } else if (put_page_testzero(page)) {
154 if (PageHead(page))
155 __put_compound_page(page);
156 else
157 __put_single_page(page);
Nick Piggin8519fb32006-02-07 12:58:52 -0800158 }
159}
160
Linus Torvalds1da177e2005-04-16 15:20:36 -0700161void put_page(struct page *page)
162{
Nick Piggin8519fb32006-02-07 12:58:52 -0800163 if (unlikely(PageCompound(page)))
164 put_compound_page(page);
165 else if (put_page_testzero(page))
Andrea Arcangeli91807062011-01-13 15:46:32 -0800166 __put_single_page(page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700167}
168EXPORT_SYMBOL(put_page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700169
Andrea Arcangeli70b50f92011-11-02 13:36:59 -0700170/*
171 * This function is exported but must not be called by anything other
172 * than get_page(). It implements the slow path of get_page().
173 */
174bool __get_page_tail(struct page *page)
175{
176 /*
177 * This takes care of get_page() if run on a tail page
178 * returned by one of the get_user_pages/follow_page variants.
179 * get_user_pages/follow_page itself doesn't need the compound
180 * lock because it runs __get_page_tail_foll() under the
181 * proper PT lock that already serializes against
182 * split_huge_page().
183 */
184 unsigned long flags;
185 bool got = false;
186 struct page *page_head = compound_trans_head(page);
187
188 if (likely(page != page_head && get_page_unless_zero(page_head))) {
Pravin B Shelar5bf5f032012-05-29 15:06:49 -0700189
190 /* Ref to put_compound_page() comment. */
191 if (PageSlab(page_head)) {
192 if (likely(PageTail(page))) {
193 __get_page_tail_foll(page, false);
194 return true;
195 } else {
196 put_page(page_head);
197 return false;
198 }
199 }
200
Andrea Arcangeli70b50f92011-11-02 13:36:59 -0700201 /*
202 * page_head wasn't a dangling pointer but it
203 * may not be a head page anymore by the time
204 * we obtain the lock. That is ok as long as it
205 * can't be freed from under us.
206 */
207 flags = compound_lock_irqsave(page_head);
208 /* here __split_huge_page_refcount won't run anymore */
209 if (likely(PageTail(page))) {
210 __get_page_tail_foll(page, false);
211 got = true;
212 }
213 compound_unlock_irqrestore(page_head, flags);
214 if (unlikely(!got))
215 put_page(page_head);
216 }
217 return got;
218}
219EXPORT_SYMBOL(__get_page_tail);
220
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -0700221/**
Randy Dunlap76824862008-03-19 17:00:40 -0700222 * put_pages_list() - release a list of pages
223 * @pages: list of pages threaded on page->lru
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -0700224 *
225 * Release a list of pages which are strung together on page.lru. Currently
226 * used by read_cache_pages() and related error recovery code.
Alexander Zarochentsev1d7ea732006-08-13 23:24:27 -0700227 */
228void put_pages_list(struct list_head *pages)
229{
230 while (!list_empty(pages)) {
231 struct page *victim;
232
233 victim = list_entry(pages->prev, struct page, lru);
234 list_del(&victim->lru);
235 page_cache_release(victim);
236 }
237}
238EXPORT_SYMBOL(put_pages_list);
239
Mel Gorman18022c52012-07-31 16:44:51 -0700240/*
241 * get_kernel_pages() - pin kernel pages in memory
242 * @kiov: An array of struct kvec structures
243 * @nr_segs: number of segments to pin
244 * @write: pinning for read/write, currently ignored
245 * @pages: array that receives pointers to the pages pinned.
246 * Should be at least nr_segs long.
247 *
248 * Returns number of pages pinned. This may be fewer than the number
249 * requested. If nr_pages is 0 or negative, returns 0. If no pages
250 * were pinned, returns -errno. Each page returned must be released
251 * with a put_page() call when it is finished with.
252 */
253int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
254 struct page **pages)
255{
256 int seg;
257
258 for (seg = 0; seg < nr_segs; seg++) {
259 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
260 return seg;
261
Mel Gorman5a178112012-07-31 16:45:02 -0700262 pages[seg] = kmap_to_page(kiov[seg].iov_base);
Mel Gorman18022c52012-07-31 16:44:51 -0700263 page_cache_get(pages[seg]);
264 }
265
266 return seg;
267}
268EXPORT_SYMBOL_GPL(get_kernel_pages);
269
270/*
271 * get_kernel_page() - pin a kernel page in memory
272 * @start: starting kernel address
273 * @write: pinning for read/write, currently ignored
274 * @pages: array that receives pointer to the page pinned.
275 * Must be at least nr_segs long.
276 *
277 * Returns 1 if page is pinned. If the page was not pinned, returns
278 * -errno. The page returned must be released with a put_page() call
279 * when it is finished with.
280 */
281int get_kernel_page(unsigned long start, int write, struct page **pages)
282{
283 const struct kvec kiov = {
284 .iov_base = (void *)start,
285 .iov_len = PAGE_SIZE
286 };
287
288 return get_kernel_pages(&kiov, 1, write, pages);
289}
290EXPORT_SYMBOL_GPL(get_kernel_page);
291
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700292static void pagevec_lru_move_fn(struct pagevec *pvec,
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700293 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
294 void *arg)
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700295{
296 int i;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700297 struct zone *zone = NULL;
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700298 struct lruvec *lruvec;
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700299 unsigned long flags = 0;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700300
301 for (i = 0; i < pagevec_count(pvec); i++) {
302 struct page *page = pvec->pages[i];
303 struct zone *pagezone = page_zone(page);
304
305 if (pagezone != zone) {
306 if (zone)
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700307 spin_unlock_irqrestore(&zone->lru_lock, flags);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700308 zone = pagezone;
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700309 spin_lock_irqsave(&zone->lru_lock, flags);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700310 }
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700311
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700312 lruvec = mem_cgroup_page_lruvec(page, zone);
313 (*move_fn)(page, lruvec, arg);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700314 }
315 if (zone)
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700316 spin_unlock_irqrestore(&zone->lru_lock, flags);
Linus Torvalds83896fb2011-01-17 14:42:34 -0800317 release_pages(pvec->pages, pvec->nr, pvec->cold);
318 pagevec_reinit(pvec);
Shaohua Lid8505de2011-01-13 15:47:33 -0800319}
320
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700321static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
322 void *arg)
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700323{
324 int *pgmoved = arg;
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700325
326 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
327 enum lru_list lru = page_lru_base_type(page);
Johannes Weiner925b7672012-01-12 17:18:15 -0800328 list_move_tail(&page->lru, &lruvec->lists[lru]);
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700329 (*pgmoved)++;
330 }
331}
332
333/*
334 * pagevec_move_tail() must be called with IRQ disabled.
335 * Otherwise this may cause nasty races.
336 */
337static void pagevec_move_tail(struct pagevec *pvec)
338{
339 int pgmoved = 0;
340
341 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
342 __count_vm_events(PGROTATED, pgmoved);
343}
344
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700345/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700346 * Writeback is about to end against a page which has been marked for immediate
347 * reclaim. If it still appears to be reclaimable, move it to the tail of the
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700348 * inactive list.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700349 */
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700350void rotate_reclaimable_page(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700351{
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700352 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700353 !PageUnevictable(page) && PageLRU(page)) {
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700354 struct pagevec *pvec;
355 unsigned long flags;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700356
Miklos Szerediac6aadb2008-04-28 02:12:38 -0700357 page_cache_get(page);
358 local_irq_save(flags);
359 pvec = &__get_cpu_var(lru_rotate_pvecs);
360 if (!pagevec_add(pvec, page))
361 pagevec_move_tail(pvec);
362 local_irq_restore(flags);
363 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700364}
365
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700366static void update_page_reclaim_stat(struct lruvec *lruvec,
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800367 int file, int rotated)
368{
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700369 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800370
371 reclaim_stat->recent_scanned[file]++;
372 if (rotated)
373 reclaim_stat->recent_rotated[file]++;
KOSAKI Motohiro3e2f41f2009-01-07 18:08:20 -0800374}
375
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700376static void __activate_page(struct page *page, struct lruvec *lruvec,
377 void *arg)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700378{
Linus Torvalds7a608572011-01-17 14:42:19 -0800379 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
380 int file = page_is_file_cache(page);
381 int lru = page_lru_base_type(page);
Linus Torvalds7a608572011-01-17 14:42:19 -0800382
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700383 del_page_from_lru_list(page, lruvec, lru);
Linus Torvalds7a608572011-01-17 14:42:19 -0800384 SetPageActive(page);
385 lru += LRU_ACTIVE;
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700386 add_page_to_lru_list(page, lruvec, lru);
Linus Torvalds7a608572011-01-17 14:42:19 -0800387
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700388 __count_vm_event(PGACTIVATE);
389 update_page_reclaim_stat(lruvec, file, 1);
Linus Torvalds7a608572011-01-17 14:42:19 -0800390 }
Shaohua Lieb709b02011-05-24 17:12:55 -0700391}
392
393#ifdef CONFIG_SMP
394static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
395
396static void activate_page_drain(int cpu)
397{
398 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
399
400 if (pagevec_count(pvec))
401 pagevec_lru_move_fn(pvec, __activate_page, NULL);
402}
403
404void activate_page(struct page *page)
405{
406 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
407 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
408
409 page_cache_get(page);
410 if (!pagevec_add(pvec, page))
411 pagevec_lru_move_fn(pvec, __activate_page, NULL);
412 put_cpu_var(activate_page_pvecs);
413 }
414}
415
416#else
417static inline void activate_page_drain(int cpu)
418{
419}
420
421void activate_page(struct page *page)
422{
423 struct zone *zone = page_zone(page);
424
425 spin_lock_irq(&zone->lru_lock);
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700426 __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700427 spin_unlock_irq(&zone->lru_lock);
428}
Shaohua Lieb709b02011-05-24 17:12:55 -0700429#endif
Linus Torvalds1da177e2005-04-16 15:20:36 -0700430
431/*
432 * Mark a page as having seen activity.
433 *
434 * inactive,unreferenced -> inactive,referenced
435 * inactive,referenced -> active,unreferenced
436 * active,unreferenced -> active,referenced
437 */
Harvey Harrison920c7a52008-02-04 22:29:26 -0800438void mark_page_accessed(struct page *page)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700439{
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700440 if (!PageActive(page) && !PageUnevictable(page) &&
441 PageReferenced(page) && PageLRU(page)) {
Linus Torvalds1da177e2005-04-16 15:20:36 -0700442 activate_page(page);
443 ClearPageReferenced(page);
444 } else if (!PageReferenced(page)) {
445 SetPageReferenced(page);
446 }
447}
Linus Torvalds1da177e2005-04-16 15:20:36 -0700448EXPORT_SYMBOL(mark_page_accessed);
449
Robin Dongd741c9c2012-10-08 16:29:05 -0700450/*
451 * Order of operations is important: flush the pagevec when it's already
452 * full, not when adding the last page, to make sure that last page is
453 * not added to the LRU directly when passed to this function. Because
454 * mark_page_accessed() (called after this when writing) only activates
455 * pages that are on the LRU, linear writes in subpage chunks would see
456 * every PAGEVEC_SIZE page activated, which is unexpected.
457 */
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700458void __lru_cache_add(struct page *page, enum lru_list lru)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700459{
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700460 struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700461
462 page_cache_get(page);
Robin Dongd741c9c2012-10-08 16:29:05 -0700463 if (!pagevec_space(pvec))
Hugh Dickins5095ae832012-01-12 17:19:58 -0800464 __pagevec_lru_add(pvec, lru);
Robin Dongd741c9c2012-10-08 16:29:05 -0700465 pagevec_add(pvec, page);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700466 put_cpu_var(lru_add_pvecs);
467}
Miklos Szeredi47846b02010-05-25 15:06:06 +0200468EXPORT_SYMBOL(__lru_cache_add);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700469
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700470/**
471 * lru_cache_add_lru - add a page to a page list
472 * @page: the page to be added to the LRU.
473 * @lru: the LRU list to which the page is added.
474 */
475void lru_cache_add_lru(struct page *page, enum lru_list lru)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700476{
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700477 if (PageActive(page)) {
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700478 VM_BUG_ON(PageUnevictable(page));
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700479 ClearPageActive(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700480 } else if (PageUnevictable(page)) {
481 VM_BUG_ON(PageActive(page));
482 ClearPageUnevictable(page);
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700483 }
Linus Torvalds1da177e2005-04-16 15:20:36 -0700484
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700485 VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page));
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700486 __lru_cache_add(page, lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700487}
488
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700489/**
490 * add_page_to_unevictable_list - add a page to the unevictable list
491 * @page: the page to be added to the unevictable list
492 *
493 * Add page directly to its zone's unevictable list. To avoid races with
494 * tasks that might be making the page evictable, through eg. munlock,
495 * munmap or exit, while it's not on the lru, we want to add the page
496 * while it's locked or otherwise "invisible" to other tasks. This is
497 * difficult to do when using the pagevec cache, so bypass that.
498 */
499void add_page_to_unevictable_list(struct page *page)
500{
501 struct zone *zone = page_zone(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700502 struct lruvec *lruvec;
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700503
504 spin_lock_irq(&zone->lru_lock);
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700505 lruvec = mem_cgroup_page_lruvec(page, zone);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700506 SetPageUnevictable(page);
507 SetPageLRU(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700508 add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700509 spin_unlock_irq(&zone->lru_lock);
510}
511
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700512/*
Minchan Kim31560182011-03-22 16:32:52 -0700513 * If the page can not be invalidated, it is moved to the
514 * inactive list to speed up its reclaim. It is moved to the
515 * head of the list, rather than the tail, to give the flusher
516 * threads some time to write it out, as this is much more
517 * effective than the single-page writeout from reclaim.
Minchan Kim278df9f2011-03-22 16:32:54 -0700518 *
519 * If the page isn't page_mapped and dirty/writeback, the page
520 * could reclaim asap using PG_reclaim.
521 *
522 * 1. active, mapped page -> none
523 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
524 * 3. inactive, mapped page -> none
525 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
526 * 5. inactive, clean -> inactive, tail
527 * 6. Others -> none
528 *
529 * In 4, why it moves inactive's head, the VM expects the page would
530 * be write it out by flusher threads as this is much more effective
531 * than the single-page writeout from reclaim.
Minchan Kim31560182011-03-22 16:32:52 -0700532 */
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700533static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
534 void *arg)
Minchan Kim31560182011-03-22 16:32:52 -0700535{
536 int lru, file;
Minchan Kim278df9f2011-03-22 16:32:54 -0700537 bool active;
Minchan Kim31560182011-03-22 16:32:52 -0700538
Minchan Kim278df9f2011-03-22 16:32:54 -0700539 if (!PageLRU(page))
Minchan Kim31560182011-03-22 16:32:52 -0700540 return;
541
Minchan Kimbad49d92011-05-11 15:13:30 -0700542 if (PageUnevictable(page))
543 return;
544
Minchan Kim31560182011-03-22 16:32:52 -0700545 /* Some processes are using the page */
546 if (page_mapped(page))
547 return;
548
Minchan Kim278df9f2011-03-22 16:32:54 -0700549 active = PageActive(page);
Minchan Kim31560182011-03-22 16:32:52 -0700550 file = page_is_file_cache(page);
551 lru = page_lru_base_type(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700552
553 del_page_from_lru_list(page, lruvec, lru + active);
Minchan Kim31560182011-03-22 16:32:52 -0700554 ClearPageActive(page);
555 ClearPageReferenced(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700556 add_page_to_lru_list(page, lruvec, lru);
Minchan Kim31560182011-03-22 16:32:52 -0700557
Minchan Kim278df9f2011-03-22 16:32:54 -0700558 if (PageWriteback(page) || PageDirty(page)) {
559 /*
560 * PG_reclaim could be raced with end_page_writeback
561 * It can make readahead confusing. But race window
562 * is _really_ small and it's non-critical problem.
563 */
564 SetPageReclaim(page);
565 } else {
566 /*
567 * The page's writeback ends up during pagevec
568 * We moves tha page into tail of inactive.
569 */
Johannes Weiner925b7672012-01-12 17:18:15 -0800570 list_move_tail(&page->lru, &lruvec->lists[lru]);
Minchan Kim278df9f2011-03-22 16:32:54 -0700571 __count_vm_event(PGROTATED);
572 }
573
574 if (active)
575 __count_vm_event(PGDEACTIVATE);
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700576 update_page_reclaim_stat(lruvec, file, 0);
Minchan Kim31560182011-03-22 16:32:52 -0700577}
578
Minchan Kim31560182011-03-22 16:32:52 -0700579/*
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700580 * Drain pages out of the cpu's pagevecs.
581 * Either "cpu" is the current CPU, and preemption has already been
582 * disabled; or "cpu" is being hot-unplugged, and is already dead.
583 */
Konstantin Khlebnikovf0cb3c72012-03-21 16:34:06 -0700584void lru_add_drain_cpu(int cpu)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700585{
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700586 struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu);
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700587 struct pagevec *pvec;
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700588 int lru;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700589
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700590 for_each_lru(lru) {
591 pvec = &pvecs[lru - LRU_BASE];
592 if (pagevec_count(pvec))
Hugh Dickins5095ae832012-01-12 17:19:58 -0800593 __pagevec_lru_add(pvec, lru);
KOSAKI Motohirof04e9eb2008-10-18 20:26:19 -0700594 }
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700595
596 pvec = &per_cpu(lru_rotate_pvecs, cpu);
597 if (pagevec_count(pvec)) {
598 unsigned long flags;
599
600 /* No harm done if a racing interrupt already did this */
601 local_irq_save(flags);
602 pagevec_move_tail(pvec);
603 local_irq_restore(flags);
604 }
Minchan Kim31560182011-03-22 16:32:52 -0700605
606 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
607 if (pagevec_count(pvec))
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700608 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
Shaohua Lieb709b02011-05-24 17:12:55 -0700609
610 activate_page_drain(cpu);
Minchan Kim31560182011-03-22 16:32:52 -0700611}
612
613/**
614 * deactivate_page - forcefully deactivate a page
615 * @page: page to deactivate
616 *
617 * This function hints the VM that @page is a good reclaim candidate,
618 * for example if its invalidation fails due to the page being dirty
619 * or under writeback.
620 */
621void deactivate_page(struct page *page)
622{
Minchan Kim821ed6b2011-05-24 17:12:31 -0700623 /*
624 * In a workload with many unevictable page such as mprotect, unevictable
625 * page deactivation for accelerating reclaim is pointless.
626 */
627 if (PageUnevictable(page))
628 return;
629
Minchan Kim31560182011-03-22 16:32:52 -0700630 if (likely(get_page_unless_zero(page))) {
631 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
632
633 if (!pagevec_add(pvec, page))
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700634 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
Minchan Kim31560182011-03-22 16:32:52 -0700635 put_cpu_var(lru_deactivate_pvecs);
636 }
Andrew Morton80bfed92006-01-06 00:11:14 -0800637}
638
639void lru_add_drain(void)
640{
Konstantin Khlebnikovf0cb3c72012-03-21 16:34:06 -0700641 lru_add_drain_cpu(get_cpu());
Andrew Morton80bfed92006-01-06 00:11:14 -0800642 put_cpu();
Linus Torvalds1da177e2005-04-16 15:20:36 -0700643}
644
David Howellsc4028952006-11-22 14:57:56 +0000645static void lru_add_drain_per_cpu(struct work_struct *dummy)
Nick Piggin053837f2006-01-18 17:42:27 -0800646{
647 lru_add_drain();
648}
649
650/*
651 * Returns 0 for success
652 */
653int lru_add_drain_all(void)
654{
David Howellsc4028952006-11-22 14:57:56 +0000655 return schedule_on_each_cpu(lru_add_drain_per_cpu);
Nick Piggin053837f2006-01-18 17:42:27 -0800656}
657
Linus Torvalds1da177e2005-04-16 15:20:36 -0700658/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700659 * Batched page_cache_release(). Decrement the reference count on all the
660 * passed pages. If it fell to zero then remove the page from the LRU and
661 * free it.
662 *
663 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
664 * for the remainder of the operation.
665 *
Fernando Luis Vazquez Caoab33dc02008-07-29 22:33:40 -0700666 * The locking in this function is against shrink_inactive_list(): we recheck
667 * the page count inside the lock to see whether shrink_inactive_list()
668 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
669 * will free it.
Linus Torvalds1da177e2005-04-16 15:20:36 -0700670 */
671void release_pages(struct page **pages, int nr, int cold)
672{
673 int i;
Konstantin Khlebnikovcc598502012-01-10 15:07:04 -0800674 LIST_HEAD(pages_to_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700675 struct zone *zone = NULL;
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700676 struct lruvec *lruvec;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700677 unsigned long uninitialized_var(flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700678
Linus Torvalds1da177e2005-04-16 15:20:36 -0700679 for (i = 0; i < nr; i++) {
680 struct page *page = pages[i];
Linus Torvalds1da177e2005-04-16 15:20:36 -0700681
Nick Piggin8519fb32006-02-07 12:58:52 -0800682 if (unlikely(PageCompound(page))) {
683 if (zone) {
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700684 spin_unlock_irqrestore(&zone->lru_lock, flags);
Nick Piggin8519fb32006-02-07 12:58:52 -0800685 zone = NULL;
686 }
687 put_compound_page(page);
688 continue;
689 }
690
Nick Pigginb5810032005-10-29 18:16:12 -0700691 if (!put_page_testzero(page))
Linus Torvalds1da177e2005-04-16 15:20:36 -0700692 continue;
693
Nick Piggin46453a62006-03-22 00:07:58 -0800694 if (PageLRU(page)) {
695 struct zone *pagezone = page_zone(page);
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700696
Nick Piggin46453a62006-03-22 00:07:58 -0800697 if (pagezone != zone) {
698 if (zone)
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700699 spin_unlock_irqrestore(&zone->lru_lock,
700 flags);
Nick Piggin46453a62006-03-22 00:07:58 -0800701 zone = pagezone;
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700702 spin_lock_irqsave(&zone->lru_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700703 }
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700704
705 lruvec = mem_cgroup_page_lruvec(page, zone);
Nick Piggin725d7042006-09-25 23:30:55 -0700706 VM_BUG_ON(!PageLRU(page));
Nick Piggin67453912006-03-22 00:08:00 -0800707 __ClearPageLRU(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700708 del_page_from_lru_list(page, lruvec, page_off_lru(page));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700709 }
Nick Piggin46453a62006-03-22 00:07:58 -0800710
Konstantin Khlebnikovcc598502012-01-10 15:07:04 -0800711 list_add(&page->lru, &pages_to_free);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700712 }
713 if (zone)
Hisashi Hifumi902aaed2007-10-16 01:24:52 -0700714 spin_unlock_irqrestore(&zone->lru_lock, flags);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700715
Konstantin Khlebnikovcc598502012-01-10 15:07:04 -0800716 free_hot_cold_page_list(&pages_to_free, cold);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700717}
Miklos Szeredi0be85572010-10-27 15:34:46 -0700718EXPORT_SYMBOL(release_pages);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700719
720/*
721 * The pages which we're about to release may be in the deferred lru-addition
722 * queues. That would prevent them from really being freed right now. That's
723 * OK from a correctness point of view but is inefficient - those pages may be
724 * cache-warm and we want to give them back to the page allocator ASAP.
725 *
726 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
727 * and __pagevec_lru_add_active() call release_pages() directly to avoid
728 * mutual recursion.
729 */
730void __pagevec_release(struct pagevec *pvec)
731{
732 lru_add_drain();
733 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
734 pagevec_reinit(pvec);
735}
Steve French7f285702005-11-01 10:22:55 -0800736EXPORT_SYMBOL(__pagevec_release);
737
Hugh Dickins12d27102012-01-12 17:19:52 -0800738#ifdef CONFIG_TRANSPARENT_HUGEPAGE
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800739/* used by __split_huge_page_refcount() */
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700740void lru_add_page_tail(struct page *page, struct page *page_tail,
Shaohua Li5bc7b8a2013-04-29 15:08:36 -0700741 struct lruvec *lruvec, struct list_head *list)
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800742{
Hugh Dickins75121022012-03-05 14:59:18 -0800743 int uninitialized_var(active);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800744 enum lru_list lru;
745 const int file = 0;
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800746
747 VM_BUG_ON(!PageHead(page));
748 VM_BUG_ON(PageCompound(page_tail));
749 VM_BUG_ON(PageLRU(page_tail));
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700750 VM_BUG_ON(NR_CPUS != 1 &&
751 !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800752
Shaohua Li5bc7b8a2013-04-29 15:08:36 -0700753 if (!list)
754 SetPageLRU(page_tail);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800755
Hugh Dickins39b5f292012-10-08 16:33:18 -0700756 if (page_evictable(page_tail)) {
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800757 if (PageActive(page)) {
758 SetPageActive(page_tail);
759 active = 1;
760 lru = LRU_ACTIVE_ANON;
761 } else {
762 active = 0;
763 lru = LRU_INACTIVE_ANON;
764 }
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800765 } else {
766 SetPageUnevictable(page_tail);
Hugh Dickins12d27102012-01-12 17:19:52 -0800767 lru = LRU_UNEVICTABLE;
768 }
769
770 if (likely(PageLRU(page)))
771 list_add_tail(&page_tail->lru, &page->lru);
Shaohua Li5bc7b8a2013-04-29 15:08:36 -0700772 else if (list) {
773 /* page reclaim is reclaiming a huge page */
774 get_page(page_tail);
775 list_add_tail(&page_tail->lru, list);
776 } else {
Hugh Dickins12d27102012-01-12 17:19:52 -0800777 struct list_head *list_head;
778 /*
779 * Head page has not yet been counted, as an hpage,
780 * so we must account for each subpage individually.
781 *
782 * Use the standard add function to put page_tail on the list,
783 * but then correct its position so they all end up in order.
784 */
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700785 add_page_to_lru_list(page_tail, lruvec, lru);
Hugh Dickins12d27102012-01-12 17:19:52 -0800786 list_head = page_tail->lru.prev;
787 list_move_tail(&page_tail->lru, list_head);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800788 }
Hugh Dickins75121022012-03-05 14:59:18 -0800789
790 if (!PageUnevictable(page))
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700791 update_page_reclaim_stat(lruvec, file, active);
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800792}
Hugh Dickins12d27102012-01-12 17:19:52 -0800793#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
Andrea Arcangeli71e3aac2011-01-13 15:46:52 -0800794
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700795static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
796 void *arg)
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700797{
798 enum lru_list lru = (enum lru_list)arg;
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700799 int file = is_file_lru(lru);
800 int active = is_active_lru(lru);
801
802 VM_BUG_ON(PageActive(page));
803 VM_BUG_ON(PageUnevictable(page));
804 VM_BUG_ON(PageLRU(page));
805
806 SetPageLRU(page);
807 if (active)
808 SetPageActive(page);
Hugh Dickinsfa9add62012-05-29 15:07:09 -0700809 add_page_to_lru_list(page, lruvec, lru);
810 update_page_reclaim_stat(lruvec, file, active);
Shaohua Li3dd7ae82011-03-22 16:33:45 -0700811}
812
Linus Torvalds1da177e2005-04-16 15:20:36 -0700813/*
Linus Torvalds1da177e2005-04-16 15:20:36 -0700814 * Add the passed pages to the LRU, then drop the caller's refcount
815 * on them. Reinitialises the caller's pagevec.
816 */
Hugh Dickins5095ae832012-01-12 17:19:58 -0800817void __pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
Linus Torvalds1da177e2005-04-16 15:20:36 -0700818{
Lee Schermerhorn894bc312008-10-18 20:26:39 -0700819 VM_BUG_ON(is_unevictable_lru(lru));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700820
Hugh Dickins5095ae832012-01-12 17:19:58 -0800821 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, (void *)lru);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700822}
Hugh Dickins5095ae832012-01-12 17:19:58 -0800823EXPORT_SYMBOL(__pagevec_lru_add);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700824
Linus Torvalds1da177e2005-04-16 15:20:36 -0700825/**
826 * pagevec_lookup - gang pagecache lookup
827 * @pvec: Where the resulting pages are placed
828 * @mapping: The address_space to search
829 * @start: The starting page index
830 * @nr_pages: The maximum number of pages
831 *
832 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
833 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
834 * reference against the pages in @pvec.
835 *
836 * The search returns a group of mapping-contiguous pages with ascending
837 * indexes. There may be holes in the indices due to not-present pages.
838 *
839 * pagevec_lookup() returns the number of pages which were found.
840 */
841unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
842 pgoff_t start, unsigned nr_pages)
843{
844 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
845 return pagevec_count(pvec);
846}
Christoph Hellwig78539fd2006-01-11 20:47:41 +1100847EXPORT_SYMBOL(pagevec_lookup);
848
Linus Torvalds1da177e2005-04-16 15:20:36 -0700849unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
850 pgoff_t *index, int tag, unsigned nr_pages)
851{
852 pvec->nr = find_get_pages_tag(mapping, index, tag,
853 nr_pages, pvec->pages);
854 return pagevec_count(pvec);
855}
Steve French7f285702005-11-01 10:22:55 -0800856EXPORT_SYMBOL(pagevec_lookup_tag);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700857
Linus Torvalds1da177e2005-04-16 15:20:36 -0700858/*
859 * Perform any setup for the swap system
860 */
861void __init swap_setup(void)
862{
Jan Beulich44813742009-09-21 17:03:05 -0700863 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700864#ifdef CONFIG_SWAP
Shaohua Li33806f02013-02-22 16:34:37 -0800865 int i;
866
867 bdi_init(swapper_spaces[0].backing_dev_info);
868 for (i = 0; i < MAX_SWAPFILES; i++) {
869 spin_lock_init(&swapper_spaces[i].tree_lock);
870 INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear);
871 }
Peter Zijlstrae0bf68d2007-10-16 23:25:46 -0700872#endif
873
Linus Torvalds1da177e2005-04-16 15:20:36 -0700874 /* Use a smaller cluster for small-memory machines */
875 if (megs < 16)
876 page_cluster = 2;
877 else
878 page_cluster = 3;
879 /*
880 * Right now other parts of the system means that we
881 * _really_ don't want to cluster much more
882 */
Linus Torvalds1da177e2005-04-16 15:20:36 -0700883}