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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 operation 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/percpu_counter.h>
28#include <linux/percpu.h>
29#include <linux/cpu.h>
30#include <linux/notifier.h>
31#include <linux/backing-dev.h>
32#include <linux/memcontrol.h>
33#include <linux/gfp.h>
34
35#include "internal.h"
36
37/* How many pages do we try to swap or page in/out together? */
38int page_cluster;
39
40static DEFINE_PER_CPU(struct pagevec[NR_LRU_LISTS], lru_add_pvecs);
41static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
42static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
43
44/*
45 * This path almost never happens for VM activity - pages are normally
46 * freed via pagevecs. But it gets used by networking.
47 */
48static void __page_cache_release(struct page *page)
49{
50 if (PageLRU(page)) {
51 unsigned long flags;
52 struct zone *zone = page_zone(page);
53
54 spin_lock_irqsave(&zone->lru_lock, flags);
55 VM_BUG_ON(!PageLRU(page));
56 __ClearPageLRU(page);
57 del_page_from_lru(zone, page);
58 spin_unlock_irqrestore(&zone->lru_lock, flags);
59 }
60}
61
62static void __put_single_page(struct page *page)
63{
64 __page_cache_release(page);
65 free_hot_cold_page(page, 0);
66}
67
68static void __put_compound_page(struct page *page)
69{
70 compound_page_dtor *dtor;
71
72 __page_cache_release(page);
73 dtor = get_compound_page_dtor(page);
74 (*dtor)(page);
75}
76
77static void put_compound_page(struct page *page)
78{
79 if (unlikely(PageTail(page))) {
80 /* __split_huge_page_refcount can run under us */
81 struct page *page_head = page->first_page;
82 smp_rmb();
83 /*
84 * If PageTail is still set after smp_rmb() we can be sure
85 * that the page->first_page we read wasn't a dangling pointer.
86 * See __split_huge_page_refcount() smp_wmb().
87 */
88 if (likely(PageTail(page) && get_page_unless_zero(page_head))) {
89 unsigned long flags;
90 /*
91 * Verify that our page_head wasn't converted
92 * to a a regular page before we got a
93 * reference on it.
94 */
95 if (unlikely(!PageHead(page_head))) {
96 /* PageHead is cleared after PageTail */
97 smp_rmb();
98 VM_BUG_ON(PageTail(page));
99 goto out_put_head;
100 }
101 /*
102 * Only run compound_lock on a valid PageHead,
103 * after having it pinned with
104 * get_page_unless_zero() above.
105 */
106 smp_mb();
107 /* page_head wasn't a dangling pointer */
108 flags = compound_lock_irqsave(page_head);
109 if (unlikely(!PageTail(page))) {
110 /* __split_huge_page_refcount run before us */
111 compound_unlock_irqrestore(page_head, flags);
112 VM_BUG_ON(PageHead(page_head));
113 out_put_head:
114 if (put_page_testzero(page_head))
115 __put_single_page(page_head);
116 out_put_single:
117 if (put_page_testzero(page))
118 __put_single_page(page);
119 return;
120 }
121 VM_BUG_ON(page_head != page->first_page);
122 /*
123 * We can release the refcount taken by
124 * get_page_unless_zero now that
125 * split_huge_page_refcount is blocked on the
126 * compound_lock.
127 */
128 if (put_page_testzero(page_head))
129 VM_BUG_ON(1);
130 /* __split_huge_page_refcount will wait now */
131 VM_BUG_ON(atomic_read(&page->_count) <= 0);
132 atomic_dec(&page->_count);
133 VM_BUG_ON(atomic_read(&page_head->_count) <= 0);
134 compound_unlock_irqrestore(page_head, flags);
135 if (put_page_testzero(page_head)) {
136 if (PageHead(page_head))
137 __put_compound_page(page_head);
138 else
139 __put_single_page(page_head);
140 }
141 } else {
142 /* page_head is a dangling pointer */
143 VM_BUG_ON(PageTail(page));
144 goto out_put_single;
145 }
146 } else if (put_page_testzero(page)) {
147 if (PageHead(page))
148 __put_compound_page(page);
149 else
150 __put_single_page(page);
151 }
152}
153
154void put_page(struct page *page)
155{
156 if (unlikely(PageCompound(page)))
157 put_compound_page(page);
158 else if (put_page_testzero(page))
159 __put_single_page(page);
160}
161EXPORT_SYMBOL(put_page);
162
163/**
164 * put_pages_list() - release a list of pages
165 * @pages: list of pages threaded on page->lru
166 *
167 * Release a list of pages which are strung together on page.lru. Currently
168 * used by read_cache_pages() and related error recovery code.
169 */
170void put_pages_list(struct list_head *pages)
171{
172 while (!list_empty(pages)) {
173 struct page *victim;
174
175 victim = list_entry(pages->prev, struct page, lru);
176 list_del(&victim->lru);
177 page_cache_release(victim);
178 }
179}
180EXPORT_SYMBOL(put_pages_list);
181
182static void pagevec_lru_move_fn(struct pagevec *pvec,
183 void (*move_fn)(struct page *page, void *arg),
184 void *arg)
185{
186 int i;
187 struct zone *zone = NULL;
188 unsigned long flags = 0;
189
190 for (i = 0; i < pagevec_count(pvec); i++) {
191 struct page *page = pvec->pages[i];
192 struct zone *pagezone = page_zone(page);
193
194 if (pagezone != zone) {
195 if (zone)
196 spin_unlock_irqrestore(&zone->lru_lock, flags);
197 zone = pagezone;
198 spin_lock_irqsave(&zone->lru_lock, flags);
199 }
200
201 (*move_fn)(page, arg);
202 }
203 if (zone)
204 spin_unlock_irqrestore(&zone->lru_lock, flags);
205 release_pages(pvec->pages, pvec->nr, pvec->cold);
206 pagevec_reinit(pvec);
207}
208
209static void pagevec_move_tail_fn(struct page *page, void *arg)
210{
211 int *pgmoved = arg;
212 struct zone *zone = page_zone(page);
213
214 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
215 enum lru_list lru = page_lru_base_type(page);
216 list_move_tail(&page->lru, &zone->lru[lru].list);
217 mem_cgroup_rotate_reclaimable_page(page);
218 (*pgmoved)++;
219 }
220}
221
222/*
223 * pagevec_move_tail() must be called with IRQ disabled.
224 * Otherwise this may cause nasty races.
225 */
226static void pagevec_move_tail(struct pagevec *pvec)
227{
228 int pgmoved = 0;
229
230 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
231 __count_vm_events(PGROTATED, pgmoved);
232}
233
234/*
235 * Writeback is about to end against a page which has been marked for immediate
236 * reclaim. If it still appears to be reclaimable, move it to the tail of the
237 * inactive list.
238 */
239void rotate_reclaimable_page(struct page *page)
240{
241 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
242 !PageUnevictable(page) && PageLRU(page)) {
243 struct pagevec *pvec;
244 unsigned long flags;
245
246 page_cache_get(page);
247 local_irq_save(flags);
248 pvec = &__get_cpu_var(lru_rotate_pvecs);
249 if (!pagevec_add(pvec, page))
250 pagevec_move_tail(pvec);
251 local_irq_restore(flags);
252 }
253}
254
255static void update_page_reclaim_stat(struct zone *zone, struct page *page,
256 int file, int rotated)
257{
258 struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat;
259 struct zone_reclaim_stat *memcg_reclaim_stat;
260
261 memcg_reclaim_stat = mem_cgroup_get_reclaim_stat_from_page(page);
262
263 reclaim_stat->recent_scanned[file]++;
264 if (rotated)
265 reclaim_stat->recent_rotated[file]++;
266
267 if (!memcg_reclaim_stat)
268 return;
269
270 memcg_reclaim_stat->recent_scanned[file]++;
271 if (rotated)
272 memcg_reclaim_stat->recent_rotated[file]++;
273}
274
275static void __activate_page(struct page *page, void *arg)
276{
277 struct zone *zone = page_zone(page);
278
279 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
280 int file = page_is_file_cache(page);
281 int lru = page_lru_base_type(page);
282 del_page_from_lru_list(zone, page, lru);
283
284 SetPageActive(page);
285 lru += LRU_ACTIVE;
286 add_page_to_lru_list(zone, page, lru);
287 __count_vm_event(PGACTIVATE);
288
289 update_page_reclaim_stat(zone, page, file, 1);
290 }
291}
292
293#ifdef CONFIG_SMP
294static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
295
296static void activate_page_drain(int cpu)
297{
298 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
299
300 if (pagevec_count(pvec))
301 pagevec_lru_move_fn(pvec, __activate_page, NULL);
302}
303
304void activate_page(struct page *page)
305{
306 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
307 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
308
309 page_cache_get(page);
310 if (!pagevec_add(pvec, page))
311 pagevec_lru_move_fn(pvec, __activate_page, NULL);
312 put_cpu_var(activate_page_pvecs);
313 }
314}
315
316#else
317static inline void activate_page_drain(int cpu)
318{
319}
320
321void activate_page(struct page *page)
322{
323 struct zone *zone = page_zone(page);
324
325 spin_lock_irq(&zone->lru_lock);
326 __activate_page(page, NULL);
327 spin_unlock_irq(&zone->lru_lock);
328}
329#endif
330
331/*
332 * Mark a page as having seen activity.
333 *
334 * inactive,unreferenced -> inactive,referenced
335 * inactive,referenced -> active,unreferenced
336 * active,unreferenced -> active,referenced
337 */
338void mark_page_accessed(struct page *page)
339{
340 if (!PageActive(page) && !PageUnevictable(page) &&
341 PageReferenced(page) && PageLRU(page)) {
342 activate_page(page);
343 ClearPageReferenced(page);
344 } else if (!PageReferenced(page)) {
345 SetPageReferenced(page);
346 }
347}
348
349EXPORT_SYMBOL(mark_page_accessed);
350
351void __lru_cache_add(struct page *page, enum lru_list lru)
352{
353 struct pagevec *pvec = &get_cpu_var(lru_add_pvecs)[lru];
354
355 page_cache_get(page);
356 if (!pagevec_add(pvec, page))
357 ____pagevec_lru_add(pvec, lru);
358 put_cpu_var(lru_add_pvecs);
359}
360EXPORT_SYMBOL(__lru_cache_add);
361
362/**
363 * lru_cache_add_lru - add a page to a page list
364 * @page: the page to be added to the LRU.
365 * @lru: the LRU list to which the page is added.
366 */
367void lru_cache_add_lru(struct page *page, enum lru_list lru)
368{
369 if (PageActive(page)) {
370 VM_BUG_ON(PageUnevictable(page));
371 ClearPageActive(page);
372 } else if (PageUnevictable(page)) {
373 VM_BUG_ON(PageActive(page));
374 ClearPageUnevictable(page);
375 }
376
377 VM_BUG_ON(PageLRU(page) || PageActive(page) || PageUnevictable(page));
378 __lru_cache_add(page, lru);
379}
380
381/**
382 * add_page_to_unevictable_list - add a page to the unevictable list
383 * @page: the page to be added to the unevictable list
384 *
385 * Add page directly to its zone's unevictable list. To avoid races with
386 * tasks that might be making the page evictable, through eg. munlock,
387 * munmap or exit, while it's not on the lru, we want to add the page
388 * while it's locked or otherwise "invisible" to other tasks. This is
389 * difficult to do when using the pagevec cache, so bypass that.
390 */
391void add_page_to_unevictable_list(struct page *page)
392{
393 struct zone *zone = page_zone(page);
394
395 spin_lock_irq(&zone->lru_lock);
396 SetPageUnevictable(page);
397 SetPageLRU(page);
398 add_page_to_lru_list(zone, page, LRU_UNEVICTABLE);
399 spin_unlock_irq(&zone->lru_lock);
400}
401
402/*
403 * If the page can not be invalidated, it is moved to the
404 * inactive list to speed up its reclaim. It is moved to the
405 * head of the list, rather than the tail, to give the flusher
406 * threads some time to write it out, as this is much more
407 * effective than the single-page writeout from reclaim.
408 *
409 * If the page isn't page_mapped and dirty/writeback, the page
410 * could reclaim asap using PG_reclaim.
411 *
412 * 1. active, mapped page -> none
413 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
414 * 3. inactive, mapped page -> none
415 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
416 * 5. inactive, clean -> inactive, tail
417 * 6. Others -> none
418 *
419 * In 4, why it moves inactive's head, the VM expects the page would
420 * be write it out by flusher threads as this is much more effective
421 * than the single-page writeout from reclaim.
422 */
423static void lru_deactivate_fn(struct page *page, void *arg)
424{
425 int lru, file;
426 bool active;
427 struct zone *zone = page_zone(page);
428
429 if (!PageLRU(page))
430 return;
431
432 if (PageUnevictable(page))
433 return;
434
435 /* Some processes are using the page */
436 if (page_mapped(page))
437 return;
438
439 active = PageActive(page);
440
441 file = page_is_file_cache(page);
442 lru = page_lru_base_type(page);
443 del_page_from_lru_list(zone, page, lru + active);
444 ClearPageActive(page);
445 ClearPageReferenced(page);
446 add_page_to_lru_list(zone, page, lru);
447
448 if (PageWriteback(page) || PageDirty(page)) {
449 /*
450 * PG_reclaim could be raced with end_page_writeback
451 * It can make readahead confusing. But race window
452 * is _really_ small and it's non-critical problem.
453 */
454 SetPageReclaim(page);
455 } else {
456 /*
457 * The page's writeback ends up during pagevec
458 * We moves tha page into tail of inactive.
459 */
460 list_move_tail(&page->lru, &zone->lru[lru].list);
461 mem_cgroup_rotate_reclaimable_page(page);
462 __count_vm_event(PGROTATED);
463 }
464
465 if (active)
466 __count_vm_event(PGDEACTIVATE);
467 update_page_reclaim_stat(zone, page, file, 0);
468}
469
470/*
471 * Drain pages out of the cpu's pagevecs.
472 * Either "cpu" is the current CPU, and preemption has already been
473 * disabled; or "cpu" is being hot-unplugged, and is already dead.
474 */
475static void drain_cpu_pagevecs(int cpu)
476{
477 struct pagevec *pvecs = per_cpu(lru_add_pvecs, cpu);
478 struct pagevec *pvec;
479 int lru;
480
481 for_each_lru(lru) {
482 pvec = &pvecs[lru - LRU_BASE];
483 if (pagevec_count(pvec))
484 ____pagevec_lru_add(pvec, lru);
485 }
486
487 pvec = &per_cpu(lru_rotate_pvecs, cpu);
488 if (pagevec_count(pvec)) {
489 unsigned long flags;
490
491 /* No harm done if a racing interrupt already did this */
492 local_irq_save(flags);
493 pagevec_move_tail(pvec);
494 local_irq_restore(flags);
495 }
496
497 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
498 if (pagevec_count(pvec))
499 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
500
501 activate_page_drain(cpu);
502}
503
504/**
505 * deactivate_page - forcefully deactivate a page
506 * @page: page to deactivate
507 *
508 * This function hints the VM that @page is a good reclaim candidate,
509 * for example if its invalidation fails due to the page being dirty
510 * or under writeback.
511 */
512void deactivate_page(struct page *page)
513{
514 /*
515 * In a workload with many unevictable page such as mprotect, unevictable
516 * page deactivation for accelerating reclaim is pointless.
517 */
518 if (PageUnevictable(page))
519 return;
520
521 if (likely(get_page_unless_zero(page))) {
522 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
523
524 if (!pagevec_add(pvec, page))
525 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
526 put_cpu_var(lru_deactivate_pvecs);
527 }
528}
529
530void lru_add_drain(void)
531{
532 drain_cpu_pagevecs(get_cpu());
533 put_cpu();
534}
535
536static void lru_add_drain_per_cpu(struct work_struct *dummy)
537{
538 lru_add_drain();
539}
540
541/*
542 * Returns 0 for success
543 */
544int lru_add_drain_all(void)
545{
546 return schedule_on_each_cpu(lru_add_drain_per_cpu);
547}
548
549/*
550 * Batched page_cache_release(). Decrement the reference count on all the
551 * passed pages. If it fell to zero then remove the page from the LRU and
552 * free it.
553 *
554 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
555 * for the remainder of the operation.
556 *
557 * The locking in this function is against shrink_inactive_list(): we recheck
558 * the page count inside the lock to see whether shrink_inactive_list()
559 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
560 * will free it.
561 */
562void release_pages(struct page **pages, int nr, int cold)
563{
564 int i;
565 struct pagevec pages_to_free;
566 struct zone *zone = NULL;
567 unsigned long uninitialized_var(flags);
568
569 pagevec_init(&pages_to_free, cold);
570 for (i = 0; i < nr; i++) {
571 struct page *page = pages[i];
572
573 if (unlikely(PageCompound(page))) {
574 if (zone) {
575 spin_unlock_irqrestore(&zone->lru_lock, flags);
576 zone = NULL;
577 }
578 put_compound_page(page);
579 continue;
580 }
581
582 if (!put_page_testzero(page))
583 continue;
584
585 if (PageLRU(page)) {
586 struct zone *pagezone = page_zone(page);
587
588 if (pagezone != zone) {
589 if (zone)
590 spin_unlock_irqrestore(&zone->lru_lock,
591 flags);
592 zone = pagezone;
593 spin_lock_irqsave(&zone->lru_lock, flags);
594 }
595 VM_BUG_ON(!PageLRU(page));
596 __ClearPageLRU(page);
597 del_page_from_lru(zone, page);
598 }
599
600 if (!pagevec_add(&pages_to_free, page)) {
601 if (zone) {
602 spin_unlock_irqrestore(&zone->lru_lock, flags);
603 zone = NULL;
604 }
605 __pagevec_free(&pages_to_free);
606 pagevec_reinit(&pages_to_free);
607 }
608 }
609 if (zone)
610 spin_unlock_irqrestore(&zone->lru_lock, flags);
611
612 pagevec_free(&pages_to_free);
613}
614EXPORT_SYMBOL(release_pages);
615
616/*
617 * The pages which we're about to release may be in the deferred lru-addition
618 * queues. That would prevent them from really being freed right now. That's
619 * OK from a correctness point of view but is inefficient - those pages may be
620 * cache-warm and we want to give them back to the page allocator ASAP.
621 *
622 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
623 * and __pagevec_lru_add_active() call release_pages() directly to avoid
624 * mutual recursion.
625 */
626void __pagevec_release(struct pagevec *pvec)
627{
628 lru_add_drain();
629 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
630 pagevec_reinit(pvec);
631}
632
633EXPORT_SYMBOL(__pagevec_release);
634
635/* used by __split_huge_page_refcount() */
636void lru_add_page_tail(struct zone* zone,
637 struct page *page, struct page *page_tail)
638{
639 int active;
640 enum lru_list lru;
641 const int file = 0;
642 struct list_head *head;
643
644 VM_BUG_ON(!PageHead(page));
645 VM_BUG_ON(PageCompound(page_tail));
646 VM_BUG_ON(PageLRU(page_tail));
647 VM_BUG_ON(!spin_is_locked(&zone->lru_lock));
648
649 SetPageLRU(page_tail);
650
651 if (page_evictable(page_tail, NULL)) {
652 if (PageActive(page)) {
653 SetPageActive(page_tail);
654 active = 1;
655 lru = LRU_ACTIVE_ANON;
656 } else {
657 active = 0;
658 lru = LRU_INACTIVE_ANON;
659 }
660 update_page_reclaim_stat(zone, page_tail, file, active);
661 if (likely(PageLRU(page)))
662 head = page->lru.prev;
663 else
664 head = &zone->lru[lru].list;
665 __add_page_to_lru_list(zone, page_tail, lru, head);
666 } else {
667 SetPageUnevictable(page_tail);
668 add_page_to_lru_list(zone, page_tail, LRU_UNEVICTABLE);
669 }
670}
671
672static void ____pagevec_lru_add_fn(struct page *page, void *arg)
673{
674 enum lru_list lru = (enum lru_list)arg;
675 struct zone *zone = page_zone(page);
676 int file = is_file_lru(lru);
677 int active = is_active_lru(lru);
678
679 VM_BUG_ON(PageActive(page));
680 VM_BUG_ON(PageUnevictable(page));
681 VM_BUG_ON(PageLRU(page));
682
683 SetPageLRU(page);
684 if (active)
685 SetPageActive(page);
686 update_page_reclaim_stat(zone, page, file, active);
687 add_page_to_lru_list(zone, page, lru);
688}
689
690/*
691 * Add the passed pages to the LRU, then drop the caller's refcount
692 * on them. Reinitialises the caller's pagevec.
693 */
694void ____pagevec_lru_add(struct pagevec *pvec, enum lru_list lru)
695{
696 VM_BUG_ON(is_unevictable_lru(lru));
697
698 pagevec_lru_move_fn(pvec, ____pagevec_lru_add_fn, (void *)lru);
699}
700
701EXPORT_SYMBOL(____pagevec_lru_add);
702
703/*
704 * Try to drop buffers from the pages in a pagevec
705 */
706void pagevec_strip(struct pagevec *pvec)
707{
708 int i;
709
710 for (i = 0; i < pagevec_count(pvec); i++) {
711 struct page *page = pvec->pages[i];
712
713 if (page_has_private(page) && trylock_page(page)) {
714 if (page_has_private(page))
715 try_to_release_page(page, 0);
716 unlock_page(page);
717 }
718 }
719}
720
721/**
722 * pagevec_lookup - gang pagecache lookup
723 * @pvec: Where the resulting pages are placed
724 * @mapping: The address_space to search
725 * @start: The starting page index
726 * @nr_pages: The maximum number of pages
727 *
728 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
729 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
730 * reference against the pages in @pvec.
731 *
732 * The search returns a group of mapping-contiguous pages with ascending
733 * indexes. There may be holes in the indices due to not-present pages.
734 *
735 * pagevec_lookup() returns the number of pages which were found.
736 */
737unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
738 pgoff_t start, unsigned nr_pages)
739{
740 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
741 return pagevec_count(pvec);
742}
743
744EXPORT_SYMBOL(pagevec_lookup);
745
746unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
747 pgoff_t *index, int tag, unsigned nr_pages)
748{
749 pvec->nr = find_get_pages_tag(mapping, index, tag,
750 nr_pages, pvec->pages);
751 return pagevec_count(pvec);
752}
753
754EXPORT_SYMBOL(pagevec_lookup_tag);
755
756/*
757 * Perform any setup for the swap system
758 */
759void __init swap_setup(void)
760{
761 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
762
763#ifdef CONFIG_SWAP
764 bdi_init(swapper_space.backing_dev_info);
765#endif
766
767 /* Use a smaller cluster for small-memory machines */
768 if (megs < 16)
769 page_cluster = 2;
770 else
771 page_cluster = 3;
772 /*
773 * Right now other parts of the system means that we
774 * _really_ don't want to cluster much more
775 */
776}
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 operation 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/export.h>
25#include <linux/mm_inline.h>
26#include <linux/percpu_counter.h>
27#include <linux/percpu.h>
28#include <linux/cpu.h>
29#include <linux/notifier.h>
30#include <linux/backing-dev.h>
31#include <linux/memcontrol.h>
32#include <linux/gfp.h>
33#include <linux/uio.h>
34
35#include "internal.h"
36
37#define CREATE_TRACE_POINTS
38#include <trace/events/pagemap.h>
39
40/* How many pages do we try to swap or page in/out together? */
41int page_cluster;
42
43static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
44static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
45static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
46
47/*
48 * This path almost never happens for VM activity - pages are normally
49 * freed via pagevecs. But it gets used by networking.
50 */
51static void __page_cache_release(struct page *page)
52{
53 if (PageLRU(page)) {
54 struct zone *zone = page_zone(page);
55 struct lruvec *lruvec;
56 unsigned long flags;
57
58 spin_lock_irqsave(&zone->lru_lock, flags);
59 lruvec = mem_cgroup_page_lruvec(page, zone);
60 VM_BUG_ON_PAGE(!PageLRU(page), page);
61 __ClearPageLRU(page);
62 del_page_from_lru_list(page, lruvec, page_off_lru(page));
63 spin_unlock_irqrestore(&zone->lru_lock, flags);
64 }
65}
66
67static void __put_single_page(struct page *page)
68{
69 __page_cache_release(page);
70 free_hot_cold_page(page, 0);
71}
72
73static void __put_compound_page(struct page *page)
74{
75 compound_page_dtor *dtor;
76
77 __page_cache_release(page);
78 dtor = get_compound_page_dtor(page);
79 (*dtor)(page);
80}
81
82static void put_compound_page(struct page *page)
83{
84 struct page *page_head;
85
86 if (likely(!PageTail(page))) {
87 if (put_page_testzero(page)) {
88 /*
89 * By the time all refcounts have been released
90 * split_huge_page cannot run anymore from under us.
91 */
92 if (PageHead(page))
93 __put_compound_page(page);
94 else
95 __put_single_page(page);
96 }
97 return;
98 }
99
100 /* __split_huge_page_refcount can run under us */
101 page_head = compound_head(page);
102
103 /*
104 * THP can not break up slab pages so avoid taking
105 * compound_lock() and skip the tail page refcounting (in
106 * _mapcount) too. Slab performs non-atomic bit ops on
107 * page->flags for better performance. In particular
108 * slab_unlock() in slub used to be a hot path. It is still
109 * hot on arches that do not support
110 * this_cpu_cmpxchg_double().
111 *
112 * If "page" is part of a slab or hugetlbfs page it cannot be
113 * splitted and the head page cannot change from under us. And
114 * if "page" is part of a THP page under splitting, if the
115 * head page pointed by the THP tail isn't a THP head anymore,
116 * we'll find PageTail clear after smp_rmb() and we'll treat
117 * it as a single page.
118 */
119 if (!__compound_tail_refcounted(page_head)) {
120 /*
121 * If "page" is a THP tail, we must read the tail page
122 * flags after the head page flags. The
123 * split_huge_page side enforces write memory barriers
124 * between clearing PageTail and before the head page
125 * can be freed and reallocated.
126 */
127 smp_rmb();
128 if (likely(PageTail(page))) {
129 /*
130 * __split_huge_page_refcount cannot race
131 * here.
132 */
133 VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
134 VM_BUG_ON_PAGE(page_mapcount(page) != 0, page);
135 if (put_page_testzero(page_head)) {
136 /*
137 * If this is the tail of a slab
138 * compound page, the tail pin must
139 * not be the last reference held on
140 * the page, because the PG_slab
141 * cannot be cleared before all tail
142 * pins (which skips the _mapcount
143 * tail refcounting) have been
144 * released. For hugetlbfs the tail
145 * pin may be the last reference on
146 * the page instead, because
147 * PageHeadHuge will not go away until
148 * the compound page enters the buddy
149 * allocator.
150 */
151 VM_BUG_ON_PAGE(PageSlab(page_head), page_head);
152 __put_compound_page(page_head);
153 }
154 return;
155 } else
156 /*
157 * __split_huge_page_refcount run before us,
158 * "page" was a THP tail. The split page_head
159 * has been freed and reallocated as slab or
160 * hugetlbfs page of smaller order (only
161 * possible if reallocated as slab on x86).
162 */
163 goto out_put_single;
164 }
165
166 if (likely(page != page_head && get_page_unless_zero(page_head))) {
167 unsigned long flags;
168
169 /*
170 * page_head wasn't a dangling pointer but it may not
171 * be a head page anymore by the time we obtain the
172 * lock. That is ok as long as it can't be freed from
173 * under us.
174 */
175 flags = compound_lock_irqsave(page_head);
176 if (unlikely(!PageTail(page))) {
177 /* __split_huge_page_refcount run before us */
178 compound_unlock_irqrestore(page_head, flags);
179 if (put_page_testzero(page_head)) {
180 /*
181 * The head page may have been freed
182 * and reallocated as a compound page
183 * of smaller order and then freed
184 * again. All we know is that it
185 * cannot have become: a THP page, a
186 * compound page of higher order, a
187 * tail page. That is because we
188 * still hold the refcount of the
189 * split THP tail and page_head was
190 * the THP head before the split.
191 */
192 if (PageHead(page_head))
193 __put_compound_page(page_head);
194 else
195 __put_single_page(page_head);
196 }
197out_put_single:
198 if (put_page_testzero(page))
199 __put_single_page(page);
200 return;
201 }
202 VM_BUG_ON_PAGE(page_head != page->first_page, page);
203 /*
204 * We can release the refcount taken by
205 * get_page_unless_zero() now that
206 * __split_huge_page_refcount() is blocked on the
207 * compound_lock.
208 */
209 if (put_page_testzero(page_head))
210 VM_BUG_ON_PAGE(1, page_head);
211 /* __split_huge_page_refcount will wait now */
212 VM_BUG_ON_PAGE(page_mapcount(page) <= 0, page);
213 atomic_dec(&page->_mapcount);
214 VM_BUG_ON_PAGE(atomic_read(&page_head->_count) <= 0, page_head);
215 VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page);
216 compound_unlock_irqrestore(page_head, flags);
217
218 if (put_page_testzero(page_head)) {
219 if (PageHead(page_head))
220 __put_compound_page(page_head);
221 else
222 __put_single_page(page_head);
223 }
224 } else {
225 /* page_head is a dangling pointer */
226 VM_BUG_ON_PAGE(PageTail(page), page);
227 goto out_put_single;
228 }
229}
230
231void put_page(struct page *page)
232{
233 if (unlikely(PageCompound(page)))
234 put_compound_page(page);
235 else if (put_page_testzero(page))
236 __put_single_page(page);
237}
238EXPORT_SYMBOL(put_page);
239
240/*
241 * This function is exported but must not be called by anything other
242 * than get_page(). It implements the slow path of get_page().
243 */
244bool __get_page_tail(struct page *page)
245{
246 /*
247 * This takes care of get_page() if run on a tail page
248 * returned by one of the get_user_pages/follow_page variants.
249 * get_user_pages/follow_page itself doesn't need the compound
250 * lock because it runs __get_page_tail_foll() under the
251 * proper PT lock that already serializes against
252 * split_huge_page().
253 */
254 unsigned long flags;
255 bool got;
256 struct page *page_head = compound_head(page);
257
258 /* Ref to put_compound_page() comment. */
259 if (!__compound_tail_refcounted(page_head)) {
260 smp_rmb();
261 if (likely(PageTail(page))) {
262 /*
263 * This is a hugetlbfs page or a slab
264 * page. __split_huge_page_refcount
265 * cannot race here.
266 */
267 VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
268 __get_page_tail_foll(page, true);
269 return true;
270 } else {
271 /*
272 * __split_huge_page_refcount run
273 * before us, "page" was a THP
274 * tail. The split page_head has been
275 * freed and reallocated as slab or
276 * hugetlbfs page of smaller order
277 * (only possible if reallocated as
278 * slab on x86).
279 */
280 return false;
281 }
282 }
283
284 got = false;
285 if (likely(page != page_head && get_page_unless_zero(page_head))) {
286 /*
287 * page_head wasn't a dangling pointer but it
288 * may not be a head page anymore by the time
289 * we obtain the lock. That is ok as long as it
290 * can't be freed from under us.
291 */
292 flags = compound_lock_irqsave(page_head);
293 /* here __split_huge_page_refcount won't run anymore */
294 if (likely(PageTail(page))) {
295 __get_page_tail_foll(page, false);
296 got = true;
297 }
298 compound_unlock_irqrestore(page_head, flags);
299 if (unlikely(!got))
300 put_page(page_head);
301 }
302 return got;
303}
304EXPORT_SYMBOL(__get_page_tail);
305
306/**
307 * put_pages_list() - release a list of pages
308 * @pages: list of pages threaded on page->lru
309 *
310 * Release a list of pages which are strung together on page.lru. Currently
311 * used by read_cache_pages() and related error recovery code.
312 */
313void put_pages_list(struct list_head *pages)
314{
315 while (!list_empty(pages)) {
316 struct page *victim;
317
318 victim = list_entry(pages->prev, struct page, lru);
319 list_del(&victim->lru);
320 page_cache_release(victim);
321 }
322}
323EXPORT_SYMBOL(put_pages_list);
324
325/*
326 * get_kernel_pages() - pin kernel pages in memory
327 * @kiov: An array of struct kvec structures
328 * @nr_segs: number of segments to pin
329 * @write: pinning for read/write, currently ignored
330 * @pages: array that receives pointers to the pages pinned.
331 * Should be at least nr_segs long.
332 *
333 * Returns number of pages pinned. This may be fewer than the number
334 * requested. If nr_pages is 0 or negative, returns 0. If no pages
335 * were pinned, returns -errno. Each page returned must be released
336 * with a put_page() call when it is finished with.
337 */
338int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
339 struct page **pages)
340{
341 int seg;
342
343 for (seg = 0; seg < nr_segs; seg++) {
344 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
345 return seg;
346
347 pages[seg] = kmap_to_page(kiov[seg].iov_base);
348 page_cache_get(pages[seg]);
349 }
350
351 return seg;
352}
353EXPORT_SYMBOL_GPL(get_kernel_pages);
354
355/*
356 * get_kernel_page() - pin a kernel page in memory
357 * @start: starting kernel address
358 * @write: pinning for read/write, currently ignored
359 * @pages: array that receives pointer to the page pinned.
360 * Must be at least nr_segs long.
361 *
362 * Returns 1 if page is pinned. If the page was not pinned, returns
363 * -errno. The page returned must be released with a put_page() call
364 * when it is finished with.
365 */
366int get_kernel_page(unsigned long start, int write, struct page **pages)
367{
368 const struct kvec kiov = {
369 .iov_base = (void *)start,
370 .iov_len = PAGE_SIZE
371 };
372
373 return get_kernel_pages(&kiov, 1, write, pages);
374}
375EXPORT_SYMBOL_GPL(get_kernel_page);
376
377static void pagevec_lru_move_fn(struct pagevec *pvec,
378 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
379 void *arg)
380{
381 int i;
382 struct zone *zone = NULL;
383 struct lruvec *lruvec;
384 unsigned long flags = 0;
385
386 for (i = 0; i < pagevec_count(pvec); i++) {
387 struct page *page = pvec->pages[i];
388 struct zone *pagezone = page_zone(page);
389
390 if (pagezone != zone) {
391 if (zone)
392 spin_unlock_irqrestore(&zone->lru_lock, flags);
393 zone = pagezone;
394 spin_lock_irqsave(&zone->lru_lock, flags);
395 }
396
397 lruvec = mem_cgroup_page_lruvec(page, zone);
398 (*move_fn)(page, lruvec, arg);
399 }
400 if (zone)
401 spin_unlock_irqrestore(&zone->lru_lock, flags);
402 release_pages(pvec->pages, pvec->nr, pvec->cold);
403 pagevec_reinit(pvec);
404}
405
406static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
407 void *arg)
408{
409 int *pgmoved = arg;
410
411 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
412 enum lru_list lru = page_lru_base_type(page);
413 list_move_tail(&page->lru, &lruvec->lists[lru]);
414 (*pgmoved)++;
415 }
416}
417
418/*
419 * pagevec_move_tail() must be called with IRQ disabled.
420 * Otherwise this may cause nasty races.
421 */
422static void pagevec_move_tail(struct pagevec *pvec)
423{
424 int pgmoved = 0;
425
426 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
427 __count_vm_events(PGROTATED, pgmoved);
428}
429
430/*
431 * Writeback is about to end against a page which has been marked for immediate
432 * reclaim. If it still appears to be reclaimable, move it to the tail of the
433 * inactive list.
434 */
435void rotate_reclaimable_page(struct page *page)
436{
437 if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
438 !PageUnevictable(page) && PageLRU(page)) {
439 struct pagevec *pvec;
440 unsigned long flags;
441
442 page_cache_get(page);
443 local_irq_save(flags);
444 pvec = &__get_cpu_var(lru_rotate_pvecs);
445 if (!pagevec_add(pvec, page))
446 pagevec_move_tail(pvec);
447 local_irq_restore(flags);
448 }
449}
450
451static void update_page_reclaim_stat(struct lruvec *lruvec,
452 int file, int rotated)
453{
454 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
455
456 reclaim_stat->recent_scanned[file]++;
457 if (rotated)
458 reclaim_stat->recent_rotated[file]++;
459}
460
461static void __activate_page(struct page *page, struct lruvec *lruvec,
462 void *arg)
463{
464 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
465 int file = page_is_file_cache(page);
466 int lru = page_lru_base_type(page);
467
468 del_page_from_lru_list(page, lruvec, lru);
469 SetPageActive(page);
470 lru += LRU_ACTIVE;
471 add_page_to_lru_list(page, lruvec, lru);
472 trace_mm_lru_activate(page, page_to_pfn(page));
473
474 __count_vm_event(PGACTIVATE);
475 update_page_reclaim_stat(lruvec, file, 1);
476 }
477}
478
479#ifdef CONFIG_SMP
480static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
481
482static void activate_page_drain(int cpu)
483{
484 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
485
486 if (pagevec_count(pvec))
487 pagevec_lru_move_fn(pvec, __activate_page, NULL);
488}
489
490static bool need_activate_page_drain(int cpu)
491{
492 return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
493}
494
495void activate_page(struct page *page)
496{
497 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
498 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
499
500 page_cache_get(page);
501 if (!pagevec_add(pvec, page))
502 pagevec_lru_move_fn(pvec, __activate_page, NULL);
503 put_cpu_var(activate_page_pvecs);
504 }
505}
506
507#else
508static inline void activate_page_drain(int cpu)
509{
510}
511
512static bool need_activate_page_drain(int cpu)
513{
514 return false;
515}
516
517void activate_page(struct page *page)
518{
519 struct zone *zone = page_zone(page);
520
521 spin_lock_irq(&zone->lru_lock);
522 __activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
523 spin_unlock_irq(&zone->lru_lock);
524}
525#endif
526
527static void __lru_cache_activate_page(struct page *page)
528{
529 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
530 int i;
531
532 /*
533 * Search backwards on the optimistic assumption that the page being
534 * activated has just been added to this pagevec. Note that only
535 * the local pagevec is examined as a !PageLRU page could be in the
536 * process of being released, reclaimed, migrated or on a remote
537 * pagevec that is currently being drained. Furthermore, marking
538 * a remote pagevec's page PageActive potentially hits a race where
539 * a page is marked PageActive just after it is added to the inactive
540 * list causing accounting errors and BUG_ON checks to trigger.
541 */
542 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
543 struct page *pagevec_page = pvec->pages[i];
544
545 if (pagevec_page == page) {
546 SetPageActive(page);
547 break;
548 }
549 }
550
551 put_cpu_var(lru_add_pvec);
552}
553
554/*
555 * Mark a page as having seen activity.
556 *
557 * inactive,unreferenced -> inactive,referenced
558 * inactive,referenced -> active,unreferenced
559 * active,unreferenced -> active,referenced
560 */
561void mark_page_accessed(struct page *page)
562{
563 if (!PageActive(page) && !PageUnevictable(page) &&
564 PageReferenced(page)) {
565
566 /*
567 * If the page is on the LRU, queue it for activation via
568 * activate_page_pvecs. Otherwise, assume the page is on a
569 * pagevec, mark it active and it'll be moved to the active
570 * LRU on the next drain.
571 */
572 if (PageLRU(page))
573 activate_page(page);
574 else
575 __lru_cache_activate_page(page);
576 ClearPageReferenced(page);
577 if (page_is_file_cache(page))
578 workingset_activation(page);
579 } else if (!PageReferenced(page)) {
580 SetPageReferenced(page);
581 }
582}
583EXPORT_SYMBOL(mark_page_accessed);
584
585/*
586 * Queue the page for addition to the LRU via pagevec. The decision on whether
587 * to add the page to the [in]active [file|anon] list is deferred until the
588 * pagevec is drained. This gives a chance for the caller of __lru_cache_add()
589 * have the page added to the active list using mark_page_accessed().
590 */
591void __lru_cache_add(struct page *page)
592{
593 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
594
595 page_cache_get(page);
596 if (!pagevec_space(pvec))
597 __pagevec_lru_add(pvec);
598 pagevec_add(pvec, page);
599 put_cpu_var(lru_add_pvec);
600}
601EXPORT_SYMBOL(__lru_cache_add);
602
603/**
604 * lru_cache_add - add a page to a page list
605 * @page: the page to be added to the LRU.
606 */
607void lru_cache_add(struct page *page)
608{
609 VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
610 VM_BUG_ON_PAGE(PageLRU(page), page);
611 __lru_cache_add(page);
612}
613
614/**
615 * add_page_to_unevictable_list - add a page to the unevictable list
616 * @page: the page to be added to the unevictable list
617 *
618 * Add page directly to its zone's unevictable list. To avoid races with
619 * tasks that might be making the page evictable, through eg. munlock,
620 * munmap or exit, while it's not on the lru, we want to add the page
621 * while it's locked or otherwise "invisible" to other tasks. This is
622 * difficult to do when using the pagevec cache, so bypass that.
623 */
624void add_page_to_unevictable_list(struct page *page)
625{
626 struct zone *zone = page_zone(page);
627 struct lruvec *lruvec;
628
629 spin_lock_irq(&zone->lru_lock);
630 lruvec = mem_cgroup_page_lruvec(page, zone);
631 ClearPageActive(page);
632 SetPageUnevictable(page);
633 SetPageLRU(page);
634 add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
635 spin_unlock_irq(&zone->lru_lock);
636}
637
638/*
639 * If the page can not be invalidated, it is moved to the
640 * inactive list to speed up its reclaim. It is moved to the
641 * head of the list, rather than the tail, to give the flusher
642 * threads some time to write it out, as this is much more
643 * effective than the single-page writeout from reclaim.
644 *
645 * If the page isn't page_mapped and dirty/writeback, the page
646 * could reclaim asap using PG_reclaim.
647 *
648 * 1. active, mapped page -> none
649 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
650 * 3. inactive, mapped page -> none
651 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
652 * 5. inactive, clean -> inactive, tail
653 * 6. Others -> none
654 *
655 * In 4, why it moves inactive's head, the VM expects the page would
656 * be write it out by flusher threads as this is much more effective
657 * than the single-page writeout from reclaim.
658 */
659static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
660 void *arg)
661{
662 int lru, file;
663 bool active;
664
665 if (!PageLRU(page))
666 return;
667
668 if (PageUnevictable(page))
669 return;
670
671 /* Some processes are using the page */
672 if (page_mapped(page))
673 return;
674
675 active = PageActive(page);
676 file = page_is_file_cache(page);
677 lru = page_lru_base_type(page);
678
679 del_page_from_lru_list(page, lruvec, lru + active);
680 ClearPageActive(page);
681 ClearPageReferenced(page);
682 add_page_to_lru_list(page, lruvec, lru);
683
684 if (PageWriteback(page) || PageDirty(page)) {
685 /*
686 * PG_reclaim could be raced with end_page_writeback
687 * It can make readahead confusing. But race window
688 * is _really_ small and it's non-critical problem.
689 */
690 SetPageReclaim(page);
691 } else {
692 /*
693 * The page's writeback ends up during pagevec
694 * We moves tha page into tail of inactive.
695 */
696 list_move_tail(&page->lru, &lruvec->lists[lru]);
697 __count_vm_event(PGROTATED);
698 }
699
700 if (active)
701 __count_vm_event(PGDEACTIVATE);
702 update_page_reclaim_stat(lruvec, file, 0);
703}
704
705/*
706 * Drain pages out of the cpu's pagevecs.
707 * Either "cpu" is the current CPU, and preemption has already been
708 * disabled; or "cpu" is being hot-unplugged, and is already dead.
709 */
710void lru_add_drain_cpu(int cpu)
711{
712 struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
713
714 if (pagevec_count(pvec))
715 __pagevec_lru_add(pvec);
716
717 pvec = &per_cpu(lru_rotate_pvecs, cpu);
718 if (pagevec_count(pvec)) {
719 unsigned long flags;
720
721 /* No harm done if a racing interrupt already did this */
722 local_irq_save(flags);
723 pagevec_move_tail(pvec);
724 local_irq_restore(flags);
725 }
726
727 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
728 if (pagevec_count(pvec))
729 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
730
731 activate_page_drain(cpu);
732}
733
734/**
735 * deactivate_page - forcefully deactivate a page
736 * @page: page to deactivate
737 *
738 * This function hints the VM that @page is a good reclaim candidate,
739 * for example if its invalidation fails due to the page being dirty
740 * or under writeback.
741 */
742void deactivate_page(struct page *page)
743{
744 /*
745 * In a workload with many unevictable page such as mprotect, unevictable
746 * page deactivation for accelerating reclaim is pointless.
747 */
748 if (PageUnevictable(page))
749 return;
750
751 if (likely(get_page_unless_zero(page))) {
752 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
753
754 if (!pagevec_add(pvec, page))
755 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
756 put_cpu_var(lru_deactivate_pvecs);
757 }
758}
759
760void lru_add_drain(void)
761{
762 lru_add_drain_cpu(get_cpu());
763 put_cpu();
764}
765
766static void lru_add_drain_per_cpu(struct work_struct *dummy)
767{
768 lru_add_drain();
769}
770
771static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
772
773void lru_add_drain_all(void)
774{
775 static DEFINE_MUTEX(lock);
776 static struct cpumask has_work;
777 int cpu;
778
779 mutex_lock(&lock);
780 get_online_cpus();
781 cpumask_clear(&has_work);
782
783 for_each_online_cpu(cpu) {
784 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
785
786 if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
787 pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
788 pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
789 need_activate_page_drain(cpu)) {
790 INIT_WORK(work, lru_add_drain_per_cpu);
791 schedule_work_on(cpu, work);
792 cpumask_set_cpu(cpu, &has_work);
793 }
794 }
795
796 for_each_cpu(cpu, &has_work)
797 flush_work(&per_cpu(lru_add_drain_work, cpu));
798
799 put_online_cpus();
800 mutex_unlock(&lock);
801}
802
803/*
804 * Batched page_cache_release(). Decrement the reference count on all the
805 * passed pages. If it fell to zero then remove the page from the LRU and
806 * free it.
807 *
808 * Avoid taking zone->lru_lock if possible, but if it is taken, retain it
809 * for the remainder of the operation.
810 *
811 * The locking in this function is against shrink_inactive_list(): we recheck
812 * the page count inside the lock to see whether shrink_inactive_list()
813 * grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
814 * will free it.
815 */
816void release_pages(struct page **pages, int nr, int cold)
817{
818 int i;
819 LIST_HEAD(pages_to_free);
820 struct zone *zone = NULL;
821 struct lruvec *lruvec;
822 unsigned long uninitialized_var(flags);
823
824 for (i = 0; i < nr; i++) {
825 struct page *page = pages[i];
826
827 if (unlikely(PageCompound(page))) {
828 if (zone) {
829 spin_unlock_irqrestore(&zone->lru_lock, flags);
830 zone = NULL;
831 }
832 put_compound_page(page);
833 continue;
834 }
835
836 if (!put_page_testzero(page))
837 continue;
838
839 if (PageLRU(page)) {
840 struct zone *pagezone = page_zone(page);
841
842 if (pagezone != zone) {
843 if (zone)
844 spin_unlock_irqrestore(&zone->lru_lock,
845 flags);
846 zone = pagezone;
847 spin_lock_irqsave(&zone->lru_lock, flags);
848 }
849
850 lruvec = mem_cgroup_page_lruvec(page, zone);
851 VM_BUG_ON_PAGE(!PageLRU(page), page);
852 __ClearPageLRU(page);
853 del_page_from_lru_list(page, lruvec, page_off_lru(page));
854 }
855
856 /* Clear Active bit in case of parallel mark_page_accessed */
857 ClearPageActive(page);
858
859 list_add(&page->lru, &pages_to_free);
860 }
861 if (zone)
862 spin_unlock_irqrestore(&zone->lru_lock, flags);
863
864 free_hot_cold_page_list(&pages_to_free, cold);
865}
866EXPORT_SYMBOL(release_pages);
867
868/*
869 * The pages which we're about to release may be in the deferred lru-addition
870 * queues. That would prevent them from really being freed right now. That's
871 * OK from a correctness point of view but is inefficient - those pages may be
872 * cache-warm and we want to give them back to the page allocator ASAP.
873 *
874 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
875 * and __pagevec_lru_add_active() call release_pages() directly to avoid
876 * mutual recursion.
877 */
878void __pagevec_release(struct pagevec *pvec)
879{
880 lru_add_drain();
881 release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
882 pagevec_reinit(pvec);
883}
884EXPORT_SYMBOL(__pagevec_release);
885
886#ifdef CONFIG_TRANSPARENT_HUGEPAGE
887/* used by __split_huge_page_refcount() */
888void lru_add_page_tail(struct page *page, struct page *page_tail,
889 struct lruvec *lruvec, struct list_head *list)
890{
891 const int file = 0;
892
893 VM_BUG_ON_PAGE(!PageHead(page), page);
894 VM_BUG_ON_PAGE(PageCompound(page_tail), page);
895 VM_BUG_ON_PAGE(PageLRU(page_tail), page);
896 VM_BUG_ON(NR_CPUS != 1 &&
897 !spin_is_locked(&lruvec_zone(lruvec)->lru_lock));
898
899 if (!list)
900 SetPageLRU(page_tail);
901
902 if (likely(PageLRU(page)))
903 list_add_tail(&page_tail->lru, &page->lru);
904 else if (list) {
905 /* page reclaim is reclaiming a huge page */
906 get_page(page_tail);
907 list_add_tail(&page_tail->lru, list);
908 } else {
909 struct list_head *list_head;
910 /*
911 * Head page has not yet been counted, as an hpage,
912 * so we must account for each subpage individually.
913 *
914 * Use the standard add function to put page_tail on the list,
915 * but then correct its position so they all end up in order.
916 */
917 add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
918 list_head = page_tail->lru.prev;
919 list_move_tail(&page_tail->lru, list_head);
920 }
921
922 if (!PageUnevictable(page))
923 update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
924}
925#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
926
927static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
928 void *arg)
929{
930 int file = page_is_file_cache(page);
931 int active = PageActive(page);
932 enum lru_list lru = page_lru(page);
933
934 VM_BUG_ON_PAGE(PageLRU(page), page);
935
936 SetPageLRU(page);
937 add_page_to_lru_list(page, lruvec, lru);
938 update_page_reclaim_stat(lruvec, file, active);
939 trace_mm_lru_insertion(page, page_to_pfn(page), lru, trace_pagemap_flags(page));
940}
941
942/*
943 * Add the passed pages to the LRU, then drop the caller's refcount
944 * on them. Reinitialises the caller's pagevec.
945 */
946void __pagevec_lru_add(struct pagevec *pvec)
947{
948 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
949}
950EXPORT_SYMBOL(__pagevec_lru_add);
951
952/**
953 * pagevec_lookup_entries - gang pagecache lookup
954 * @pvec: Where the resulting entries are placed
955 * @mapping: The address_space to search
956 * @start: The starting entry index
957 * @nr_entries: The maximum number of entries
958 * @indices: The cache indices corresponding to the entries in @pvec
959 *
960 * pagevec_lookup_entries() will search for and return a group of up
961 * to @nr_entries pages and shadow entries in the mapping. All
962 * entries are placed in @pvec. pagevec_lookup_entries() takes a
963 * reference against actual pages in @pvec.
964 *
965 * The search returns a group of mapping-contiguous entries with
966 * ascending indexes. There may be holes in the indices due to
967 * not-present entries.
968 *
969 * pagevec_lookup_entries() returns the number of entries which were
970 * found.
971 */
972unsigned pagevec_lookup_entries(struct pagevec *pvec,
973 struct address_space *mapping,
974 pgoff_t start, unsigned nr_pages,
975 pgoff_t *indices)
976{
977 pvec->nr = find_get_entries(mapping, start, nr_pages,
978 pvec->pages, indices);
979 return pagevec_count(pvec);
980}
981
982/**
983 * pagevec_remove_exceptionals - pagevec exceptionals pruning
984 * @pvec: The pagevec to prune
985 *
986 * pagevec_lookup_entries() fills both pages and exceptional radix
987 * tree entries into the pagevec. This function prunes all
988 * exceptionals from @pvec without leaving holes, so that it can be
989 * passed on to page-only pagevec operations.
990 */
991void pagevec_remove_exceptionals(struct pagevec *pvec)
992{
993 int i, j;
994
995 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
996 struct page *page = pvec->pages[i];
997 if (!radix_tree_exceptional_entry(page))
998 pvec->pages[j++] = page;
999 }
1000 pvec->nr = j;
1001}
1002
1003/**
1004 * pagevec_lookup - gang pagecache lookup
1005 * @pvec: Where the resulting pages are placed
1006 * @mapping: The address_space to search
1007 * @start: The starting page index
1008 * @nr_pages: The maximum number of pages
1009 *
1010 * pagevec_lookup() will search for and return a group of up to @nr_pages pages
1011 * in the mapping. The pages are placed in @pvec. pagevec_lookup() takes a
1012 * reference against the pages in @pvec.
1013 *
1014 * The search returns a group of mapping-contiguous pages with ascending
1015 * indexes. There may be holes in the indices due to not-present pages.
1016 *
1017 * pagevec_lookup() returns the number of pages which were found.
1018 */
1019unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
1020 pgoff_t start, unsigned nr_pages)
1021{
1022 pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
1023 return pagevec_count(pvec);
1024}
1025EXPORT_SYMBOL(pagevec_lookup);
1026
1027unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
1028 pgoff_t *index, int tag, unsigned nr_pages)
1029{
1030 pvec->nr = find_get_pages_tag(mapping, index, tag,
1031 nr_pages, pvec->pages);
1032 return pagevec_count(pvec);
1033}
1034EXPORT_SYMBOL(pagevec_lookup_tag);
1035
1036/*
1037 * Perform any setup for the swap system
1038 */
1039void __init swap_setup(void)
1040{
1041 unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
1042#ifdef CONFIG_SWAP
1043 int i;
1044
1045 if (bdi_init(swapper_spaces[0].backing_dev_info))
1046 panic("Failed to init swap bdi");
1047 for (i = 0; i < MAX_SWAPFILES; i++) {
1048 spin_lock_init(&swapper_spaces[i].tree_lock);
1049 INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear);
1050 }
1051#endif
1052
1053 /* Use a smaller cluster for small-memory machines */
1054 if (megs < 16)
1055 page_cluster = 2;
1056 else
1057 page_cluster = 3;
1058 /*
1059 * Right now other parts of the system means that we
1060 * _really_ don't want to cluster much more
1061 */
1062}