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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// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * linux/mm/swap.c
4 *
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 */
7
8/*
9 * This file contains the default values for the operation of the
10 * Linux VM subsystem. Fine-tuning documentation can be found in
11 * Documentation/admin-guide/sysctl/vm.rst.
12 * Started 18.12.91
13 * Swap aging added 23.2.95, Stephen Tweedie.
14 * Buffermem limits added 12.3.98, Rik van Riel.
15 */
16
17#include <linux/mm.h>
18#include <linux/sched.h>
19#include <linux/kernel_stat.h>
20#include <linux/swap.h>
21#include <linux/mman.h>
22#include <linux/pagemap.h>
23#include <linux/pagevec.h>
24#include <linux/init.h>
25#include <linux/export.h>
26#include <linux/mm_inline.h>
27#include <linux/percpu_counter.h>
28#include <linux/memremap.h>
29#include <linux/percpu.h>
30#include <linux/cpu.h>
31#include <linux/notifier.h>
32#include <linux/backing-dev.h>
33#include <linux/memcontrol.h>
34#include <linux/gfp.h>
35#include <linux/uio.h>
36#include <linux/hugetlb.h>
37#include <linux/page_idle.h>
38
39#include "internal.h"
40
41#define CREATE_TRACE_POINTS
42#include <trace/events/pagemap.h>
43
44/* How many pages do we try to swap or page in/out together? */
45int page_cluster;
46
47static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
48static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
49static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
50static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
51static DEFINE_PER_CPU(struct pagevec, lru_lazyfree_pvecs);
52#ifdef CONFIG_SMP
53static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
54#endif
55
56/*
57 * This path almost never happens for VM activity - pages are normally
58 * freed via pagevecs. But it gets used by networking.
59 */
60static void __page_cache_release(struct page *page)
61{
62 if (PageLRU(page)) {
63 pg_data_t *pgdat = page_pgdat(page);
64 struct lruvec *lruvec;
65 unsigned long flags;
66
67 spin_lock_irqsave(&pgdat->lru_lock, flags);
68 lruvec = mem_cgroup_page_lruvec(page, pgdat);
69 VM_BUG_ON_PAGE(!PageLRU(page), page);
70 __ClearPageLRU(page);
71 del_page_from_lru_list(page, lruvec, page_off_lru(page));
72 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
73 }
74 __ClearPageWaiters(page);
75}
76
77static void __put_single_page(struct page *page)
78{
79 __page_cache_release(page);
80 mem_cgroup_uncharge(page);
81 free_unref_page(page);
82}
83
84static void __put_compound_page(struct page *page)
85{
86 compound_page_dtor *dtor;
87
88 /*
89 * __page_cache_release() is supposed to be called for thp, not for
90 * hugetlb. This is because hugetlb page does never have PageLRU set
91 * (it's never listed to any LRU lists) and no memcg routines should
92 * be called for hugetlb (it has a separate hugetlb_cgroup.)
93 */
94 if (!PageHuge(page))
95 __page_cache_release(page);
96 dtor = get_compound_page_dtor(page);
97 (*dtor)(page);
98}
99
100void __put_page(struct page *page)
101{
102 if (is_zone_device_page(page)) {
103 put_dev_pagemap(page->pgmap);
104
105 /*
106 * The page belongs to the device that created pgmap. Do
107 * not return it to page allocator.
108 */
109 return;
110 }
111
112 if (unlikely(PageCompound(page)))
113 __put_compound_page(page);
114 else
115 __put_single_page(page);
116}
117EXPORT_SYMBOL(__put_page);
118
119/**
120 * put_pages_list() - release a list of pages
121 * @pages: list of pages threaded on page->lru
122 *
123 * Release a list of pages which are strung together on page.lru. Currently
124 * used by read_cache_pages() and related error recovery code.
125 */
126void put_pages_list(struct list_head *pages)
127{
128 while (!list_empty(pages)) {
129 struct page *victim;
130
131 victim = lru_to_page(pages);
132 list_del(&victim->lru);
133 put_page(victim);
134 }
135}
136EXPORT_SYMBOL(put_pages_list);
137
138/*
139 * get_kernel_pages() - pin kernel pages in memory
140 * @kiov: An array of struct kvec structures
141 * @nr_segs: number of segments to pin
142 * @write: pinning for read/write, currently ignored
143 * @pages: array that receives pointers to the pages pinned.
144 * Should be at least nr_segs long.
145 *
146 * Returns number of pages pinned. This may be fewer than the number
147 * requested. If nr_pages is 0 or negative, returns 0. If no pages
148 * were pinned, returns -errno. Each page returned must be released
149 * with a put_page() call when it is finished with.
150 */
151int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
152 struct page **pages)
153{
154 int seg;
155
156 for (seg = 0; seg < nr_segs; seg++) {
157 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
158 return seg;
159
160 pages[seg] = kmap_to_page(kiov[seg].iov_base);
161 get_page(pages[seg]);
162 }
163
164 return seg;
165}
166EXPORT_SYMBOL_GPL(get_kernel_pages);
167
168/*
169 * get_kernel_page() - pin a kernel page in memory
170 * @start: starting kernel address
171 * @write: pinning for read/write, currently ignored
172 * @pages: array that receives pointer to the page pinned.
173 * Must be at least nr_segs long.
174 *
175 * Returns 1 if page is pinned. If the page was not pinned, returns
176 * -errno. The page returned must be released with a put_page() call
177 * when it is finished with.
178 */
179int get_kernel_page(unsigned long start, int write, struct page **pages)
180{
181 const struct kvec kiov = {
182 .iov_base = (void *)start,
183 .iov_len = PAGE_SIZE
184 };
185
186 return get_kernel_pages(&kiov, 1, write, pages);
187}
188EXPORT_SYMBOL_GPL(get_kernel_page);
189
190static void pagevec_lru_move_fn(struct pagevec *pvec,
191 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
192 void *arg)
193{
194 int i;
195 struct pglist_data *pgdat = NULL;
196 struct lruvec *lruvec;
197 unsigned long flags = 0;
198
199 for (i = 0; i < pagevec_count(pvec); i++) {
200 struct page *page = pvec->pages[i];
201 struct pglist_data *pagepgdat = page_pgdat(page);
202
203 if (pagepgdat != pgdat) {
204 if (pgdat)
205 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
206 pgdat = pagepgdat;
207 spin_lock_irqsave(&pgdat->lru_lock, flags);
208 }
209
210 lruvec = mem_cgroup_page_lruvec(page, pgdat);
211 (*move_fn)(page, lruvec, arg);
212 }
213 if (pgdat)
214 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
215 release_pages(pvec->pages, pvec->nr);
216 pagevec_reinit(pvec);
217}
218
219static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
220 void *arg)
221{
222 int *pgmoved = arg;
223
224 if (PageLRU(page) && !PageUnevictable(page)) {
225 del_page_from_lru_list(page, lruvec, page_lru(page));
226 ClearPageActive(page);
227 add_page_to_lru_list_tail(page, lruvec, page_lru(page));
228 (*pgmoved)++;
229 }
230}
231
232/*
233 * pagevec_move_tail() must be called with IRQ disabled.
234 * Otherwise this may cause nasty races.
235 */
236static void pagevec_move_tail(struct pagevec *pvec)
237{
238 int pgmoved = 0;
239
240 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
241 __count_vm_events(PGROTATED, pgmoved);
242}
243
244/*
245 * Writeback is about to end against a page which has been marked for immediate
246 * reclaim. If it still appears to be reclaimable, move it to the tail of the
247 * inactive list.
248 */
249void rotate_reclaimable_page(struct page *page)
250{
251 if (!PageLocked(page) && !PageDirty(page) &&
252 !PageUnevictable(page) && PageLRU(page)) {
253 struct pagevec *pvec;
254 unsigned long flags;
255
256 get_page(page);
257 local_irq_save(flags);
258 pvec = this_cpu_ptr(&lru_rotate_pvecs);
259 if (!pagevec_add(pvec, page) || PageCompound(page))
260 pagevec_move_tail(pvec);
261 local_irq_restore(flags);
262 }
263}
264
265static void update_page_reclaim_stat(struct lruvec *lruvec,
266 int file, int rotated)
267{
268 struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
269
270 reclaim_stat->recent_scanned[file]++;
271 if (rotated)
272 reclaim_stat->recent_rotated[file]++;
273}
274
275static void __activate_page(struct page *page, struct lruvec *lruvec,
276 void *arg)
277{
278 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
279 int file = page_is_file_cache(page);
280 int lru = page_lru_base_type(page);
281
282 del_page_from_lru_list(page, lruvec, lru);
283 SetPageActive(page);
284 lru += LRU_ACTIVE;
285 add_page_to_lru_list(page, lruvec, lru);
286 trace_mm_lru_activate(page);
287
288 __count_vm_event(PGACTIVATE);
289 update_page_reclaim_stat(lruvec, file, 1);
290 }
291}
292
293#ifdef CONFIG_SMP
294static void activate_page_drain(int cpu)
295{
296 struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
297
298 if (pagevec_count(pvec))
299 pagevec_lru_move_fn(pvec, __activate_page, NULL);
300}
301
302static bool need_activate_page_drain(int cpu)
303{
304 return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
305}
306
307void activate_page(struct page *page)
308{
309 page = compound_head(page);
310 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
311 struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
312
313 get_page(page);
314 if (!pagevec_add(pvec, page) || PageCompound(page))
315 pagevec_lru_move_fn(pvec, __activate_page, NULL);
316 put_cpu_var(activate_page_pvecs);
317 }
318}
319
320#else
321static inline void activate_page_drain(int cpu)
322{
323}
324
325void activate_page(struct page *page)
326{
327 pg_data_t *pgdat = page_pgdat(page);
328
329 page = compound_head(page);
330 spin_lock_irq(&pgdat->lru_lock);
331 __activate_page(page, mem_cgroup_page_lruvec(page, pgdat), NULL);
332 spin_unlock_irq(&pgdat->lru_lock);
333}
334#endif
335
336static void __lru_cache_activate_page(struct page *page)
337{
338 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
339 int i;
340
341 /*
342 * Search backwards on the optimistic assumption that the page being
343 * activated has just been added to this pagevec. Note that only
344 * the local pagevec is examined as a !PageLRU page could be in the
345 * process of being released, reclaimed, migrated or on a remote
346 * pagevec that is currently being drained. Furthermore, marking
347 * a remote pagevec's page PageActive potentially hits a race where
348 * a page is marked PageActive just after it is added to the inactive
349 * list causing accounting errors and BUG_ON checks to trigger.
350 */
351 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
352 struct page *pagevec_page = pvec->pages[i];
353
354 if (pagevec_page == page) {
355 SetPageActive(page);
356 break;
357 }
358 }
359
360 put_cpu_var(lru_add_pvec);
361}
362
363/*
364 * Mark a page as having seen activity.
365 *
366 * inactive,unreferenced -> inactive,referenced
367 * inactive,referenced -> active,unreferenced
368 * active,unreferenced -> active,referenced
369 *
370 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
371 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
372 */
373void mark_page_accessed(struct page *page)
374{
375 page = compound_head(page);
376 if (!PageActive(page) && !PageUnevictable(page) &&
377 PageReferenced(page)) {
378
379 /*
380 * If the page is on the LRU, queue it for activation via
381 * activate_page_pvecs. Otherwise, assume the page is on a
382 * pagevec, mark it active and it'll be moved to the active
383 * LRU on the next drain.
384 */
385 if (PageLRU(page))
386 activate_page(page);
387 else
388 __lru_cache_activate_page(page);
389 ClearPageReferenced(page);
390 if (page_is_file_cache(page))
391 workingset_activation(page);
392 } else if (!PageReferenced(page)) {
393 SetPageReferenced(page);
394 }
395 if (page_is_idle(page))
396 clear_page_idle(page);
397}
398EXPORT_SYMBOL(mark_page_accessed);
399
400static void __lru_cache_add(struct page *page)
401{
402 struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
403
404 get_page(page);
405 if (!pagevec_add(pvec, page) || PageCompound(page))
406 __pagevec_lru_add(pvec);
407 put_cpu_var(lru_add_pvec);
408}
409
410/**
411 * lru_cache_add_anon - add a page to the page lists
412 * @page: the page to add
413 */
414void lru_cache_add_anon(struct page *page)
415{
416 if (PageActive(page))
417 ClearPageActive(page);
418 __lru_cache_add(page);
419}
420
421void lru_cache_add_file(struct page *page)
422{
423 if (PageActive(page))
424 ClearPageActive(page);
425 __lru_cache_add(page);
426}
427EXPORT_SYMBOL(lru_cache_add_file);
428
429/**
430 * lru_cache_add - add a page to a page list
431 * @page: the page to be added to the LRU.
432 *
433 * Queue the page for addition to the LRU via pagevec. The decision on whether
434 * to add the page to the [in]active [file|anon] list is deferred until the
435 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
436 * have the page added to the active list using mark_page_accessed().
437 */
438void lru_cache_add(struct page *page)
439{
440 VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
441 VM_BUG_ON_PAGE(PageLRU(page), page);
442 __lru_cache_add(page);
443}
444
445/**
446 * lru_cache_add_active_or_unevictable
447 * @page: the page to be added to LRU
448 * @vma: vma in which page is mapped for determining reclaimability
449 *
450 * Place @page on the active or unevictable LRU list, depending on its
451 * evictability. Note that if the page is not evictable, it goes
452 * directly back onto it's zone's unevictable list, it does NOT use a
453 * per cpu pagevec.
454 */
455void lru_cache_add_active_or_unevictable(struct page *page,
456 struct vm_area_struct *vma)
457{
458 VM_BUG_ON_PAGE(PageLRU(page), page);
459
460 if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
461 SetPageActive(page);
462 else if (!TestSetPageMlocked(page)) {
463 /*
464 * We use the irq-unsafe __mod_zone_page_stat because this
465 * counter is not modified from interrupt context, and the pte
466 * lock is held(spinlock), which implies preemption disabled.
467 */
468 __mod_zone_page_state(page_zone(page), NR_MLOCK,
469 hpage_nr_pages(page));
470 count_vm_event(UNEVICTABLE_PGMLOCKED);
471 }
472 lru_cache_add(page);
473}
474
475/*
476 * If the page can not be invalidated, it is moved to the
477 * inactive list to speed up its reclaim. It is moved to the
478 * head of the list, rather than the tail, to give the flusher
479 * threads some time to write it out, as this is much more
480 * effective than the single-page writeout from reclaim.
481 *
482 * If the page isn't page_mapped and dirty/writeback, the page
483 * could reclaim asap using PG_reclaim.
484 *
485 * 1. active, mapped page -> none
486 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
487 * 3. inactive, mapped page -> none
488 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
489 * 5. inactive, clean -> inactive, tail
490 * 6. Others -> none
491 *
492 * In 4, why it moves inactive's head, the VM expects the page would
493 * be write it out by flusher threads as this is much more effective
494 * than the single-page writeout from reclaim.
495 */
496static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
497 void *arg)
498{
499 int lru, file;
500 bool active;
501
502 if (!PageLRU(page))
503 return;
504
505 if (PageUnevictable(page))
506 return;
507
508 /* Some processes are using the page */
509 if (page_mapped(page))
510 return;
511
512 active = PageActive(page);
513 file = page_is_file_cache(page);
514 lru = page_lru_base_type(page);
515
516 del_page_from_lru_list(page, lruvec, lru + active);
517 ClearPageActive(page);
518 ClearPageReferenced(page);
519
520 if (PageWriteback(page) || PageDirty(page)) {
521 /*
522 * PG_reclaim could be raced with end_page_writeback
523 * It can make readahead confusing. But race window
524 * is _really_ small and it's non-critical problem.
525 */
526 add_page_to_lru_list(page, lruvec, lru);
527 SetPageReclaim(page);
528 } else {
529 /*
530 * The page's writeback ends up during pagevec
531 * We moves tha page into tail of inactive.
532 */
533 add_page_to_lru_list_tail(page, lruvec, lru);
534 __count_vm_event(PGROTATED);
535 }
536
537 if (active)
538 __count_vm_event(PGDEACTIVATE);
539 update_page_reclaim_stat(lruvec, file, 0);
540}
541
542static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
543 void *arg)
544{
545 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
546 int file = page_is_file_cache(page);
547 int lru = page_lru_base_type(page);
548
549 del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
550 ClearPageActive(page);
551 ClearPageReferenced(page);
552 add_page_to_lru_list(page, lruvec, lru);
553
554 __count_vm_events(PGDEACTIVATE, hpage_nr_pages(page));
555 update_page_reclaim_stat(lruvec, file, 0);
556 }
557}
558
559static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec,
560 void *arg)
561{
562 if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
563 !PageSwapCache(page) && !PageUnevictable(page)) {
564 bool active = PageActive(page);
565
566 del_page_from_lru_list(page, lruvec,
567 LRU_INACTIVE_ANON + active);
568 ClearPageActive(page);
569 ClearPageReferenced(page);
570 /*
571 * lazyfree pages are clean anonymous pages. They have
572 * SwapBacked flag cleared to distinguish normal anonymous
573 * pages
574 */
575 ClearPageSwapBacked(page);
576 add_page_to_lru_list(page, lruvec, LRU_INACTIVE_FILE);
577
578 __count_vm_events(PGLAZYFREE, hpage_nr_pages(page));
579 count_memcg_page_event(page, PGLAZYFREE);
580 update_page_reclaim_stat(lruvec, 1, 0);
581 }
582}
583
584/*
585 * Drain pages out of the cpu's pagevecs.
586 * Either "cpu" is the current CPU, and preemption has already been
587 * disabled; or "cpu" is being hot-unplugged, and is already dead.
588 */
589void lru_add_drain_cpu(int cpu)
590{
591 struct pagevec *pvec = &per_cpu(lru_add_pvec, cpu);
592
593 if (pagevec_count(pvec))
594 __pagevec_lru_add(pvec);
595
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 }
605
606 pvec = &per_cpu(lru_deactivate_file_pvecs, cpu);
607 if (pagevec_count(pvec))
608 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
609
610 pvec = &per_cpu(lru_deactivate_pvecs, cpu);
611 if (pagevec_count(pvec))
612 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
613
614 pvec = &per_cpu(lru_lazyfree_pvecs, cpu);
615 if (pagevec_count(pvec))
616 pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
617
618 activate_page_drain(cpu);
619}
620
621/**
622 * deactivate_file_page - forcefully deactivate a file page
623 * @page: page to deactivate
624 *
625 * This function hints the VM that @page is a good reclaim candidate,
626 * for example if its invalidation fails due to the page being dirty
627 * or under writeback.
628 */
629void deactivate_file_page(struct page *page)
630{
631 /*
632 * In a workload with many unevictable page such as mprotect,
633 * unevictable page deactivation for accelerating reclaim is pointless.
634 */
635 if (PageUnevictable(page))
636 return;
637
638 if (likely(get_page_unless_zero(page))) {
639 struct pagevec *pvec = &get_cpu_var(lru_deactivate_file_pvecs);
640
641 if (!pagevec_add(pvec, page) || PageCompound(page))
642 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
643 put_cpu_var(lru_deactivate_file_pvecs);
644 }
645}
646
647/*
648 * deactivate_page - deactivate a page
649 * @page: page to deactivate
650 *
651 * deactivate_page() moves @page to the inactive list if @page was on the active
652 * list and was not an unevictable page. This is done to accelerate the reclaim
653 * of @page.
654 */
655void deactivate_page(struct page *page)
656{
657 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
658 struct pagevec *pvec = &get_cpu_var(lru_deactivate_pvecs);
659
660 get_page(page);
661 if (!pagevec_add(pvec, page) || PageCompound(page))
662 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
663 put_cpu_var(lru_deactivate_pvecs);
664 }
665}
666
667/**
668 * mark_page_lazyfree - make an anon page lazyfree
669 * @page: page to deactivate
670 *
671 * mark_page_lazyfree() moves @page to the inactive file list.
672 * This is done to accelerate the reclaim of @page.
673 */
674void mark_page_lazyfree(struct page *page)
675{
676 if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
677 !PageSwapCache(page) && !PageUnevictable(page)) {
678 struct pagevec *pvec = &get_cpu_var(lru_lazyfree_pvecs);
679
680 get_page(page);
681 if (!pagevec_add(pvec, page) || PageCompound(page))
682 pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
683 put_cpu_var(lru_lazyfree_pvecs);
684 }
685}
686
687void lru_add_drain(void)
688{
689 lru_add_drain_cpu(get_cpu());
690 put_cpu();
691}
692
693#ifdef CONFIG_SMP
694
695static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
696
697static void lru_add_drain_per_cpu(struct work_struct *dummy)
698{
699 lru_add_drain();
700}
701
702/*
703 * Doesn't need any cpu hotplug locking because we do rely on per-cpu
704 * kworkers being shut down before our page_alloc_cpu_dead callback is
705 * executed on the offlined cpu.
706 * Calling this function with cpu hotplug locks held can actually lead
707 * to obscure indirect dependencies via WQ context.
708 */
709void lru_add_drain_all(void)
710{
711 static DEFINE_MUTEX(lock);
712 static struct cpumask has_work;
713 int cpu;
714
715 /*
716 * Make sure nobody triggers this path before mm_percpu_wq is fully
717 * initialized.
718 */
719 if (WARN_ON(!mm_percpu_wq))
720 return;
721
722 mutex_lock(&lock);
723 cpumask_clear(&has_work);
724
725 for_each_online_cpu(cpu) {
726 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
727
728 if (pagevec_count(&per_cpu(lru_add_pvec, cpu)) ||
729 pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
730 pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
731 pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
732 pagevec_count(&per_cpu(lru_lazyfree_pvecs, cpu)) ||
733 need_activate_page_drain(cpu)) {
734 INIT_WORK(work, lru_add_drain_per_cpu);
735 queue_work_on(cpu, mm_percpu_wq, work);
736 cpumask_set_cpu(cpu, &has_work);
737 }
738 }
739
740 for_each_cpu(cpu, &has_work)
741 flush_work(&per_cpu(lru_add_drain_work, cpu));
742
743 mutex_unlock(&lock);
744}
745#else
746void lru_add_drain_all(void)
747{
748 lru_add_drain();
749}
750#endif
751
752/**
753 * release_pages - batched put_page()
754 * @pages: array of pages to release
755 * @nr: number of pages
756 *
757 * Decrement the reference count on all the pages in @pages. If it
758 * fell to zero, remove the page from the LRU and free it.
759 */
760void release_pages(struct page **pages, int nr)
761{
762 int i;
763 LIST_HEAD(pages_to_free);
764 struct pglist_data *locked_pgdat = NULL;
765 struct lruvec *lruvec;
766 unsigned long uninitialized_var(flags);
767 unsigned int uninitialized_var(lock_batch);
768
769 for (i = 0; i < nr; i++) {
770 struct page *page = pages[i];
771
772 /*
773 * Make sure the IRQ-safe lock-holding time does not get
774 * excessive with a continuous string of pages from the
775 * same pgdat. The lock is held only if pgdat != NULL.
776 */
777 if (locked_pgdat && ++lock_batch == SWAP_CLUSTER_MAX) {
778 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
779 locked_pgdat = NULL;
780 }
781
782 if (is_huge_zero_page(page))
783 continue;
784
785 if (is_zone_device_page(page)) {
786 if (locked_pgdat) {
787 spin_unlock_irqrestore(&locked_pgdat->lru_lock,
788 flags);
789 locked_pgdat = NULL;
790 }
791 /*
792 * ZONE_DEVICE pages that return 'false' from
793 * put_devmap_managed_page() do not require special
794 * processing, and instead, expect a call to
795 * put_page_testzero().
796 */
797 if (put_devmap_managed_page(page))
798 continue;
799 }
800
801 page = compound_head(page);
802 if (!put_page_testzero(page))
803 continue;
804
805 if (PageCompound(page)) {
806 if (locked_pgdat) {
807 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
808 locked_pgdat = NULL;
809 }
810 __put_compound_page(page);
811 continue;
812 }
813
814 if (PageLRU(page)) {
815 struct pglist_data *pgdat = page_pgdat(page);
816
817 if (pgdat != locked_pgdat) {
818 if (locked_pgdat)
819 spin_unlock_irqrestore(&locked_pgdat->lru_lock,
820 flags);
821 lock_batch = 0;
822 locked_pgdat = pgdat;
823 spin_lock_irqsave(&locked_pgdat->lru_lock, flags);
824 }
825
826 lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
827 VM_BUG_ON_PAGE(!PageLRU(page), page);
828 __ClearPageLRU(page);
829 del_page_from_lru_list(page, lruvec, page_off_lru(page));
830 }
831
832 /* Clear Active bit in case of parallel mark_page_accessed */
833 __ClearPageActive(page);
834 __ClearPageWaiters(page);
835
836 list_add(&page->lru, &pages_to_free);
837 }
838 if (locked_pgdat)
839 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
840
841 mem_cgroup_uncharge_list(&pages_to_free);
842 free_unref_page_list(&pages_to_free);
843}
844EXPORT_SYMBOL(release_pages);
845
846/*
847 * The pages which we're about to release may be in the deferred lru-addition
848 * queues. That would prevent them from really being freed right now. That's
849 * OK from a correctness point of view but is inefficient - those pages may be
850 * cache-warm and we want to give them back to the page allocator ASAP.
851 *
852 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
853 * and __pagevec_lru_add_active() call release_pages() directly to avoid
854 * mutual recursion.
855 */
856void __pagevec_release(struct pagevec *pvec)
857{
858 if (!pvec->percpu_pvec_drained) {
859 lru_add_drain();
860 pvec->percpu_pvec_drained = true;
861 }
862 release_pages(pvec->pages, pagevec_count(pvec));
863 pagevec_reinit(pvec);
864}
865EXPORT_SYMBOL(__pagevec_release);
866
867#ifdef CONFIG_TRANSPARENT_HUGEPAGE
868/* used by __split_huge_page_refcount() */
869void lru_add_page_tail(struct page *page, struct page *page_tail,
870 struct lruvec *lruvec, struct list_head *list)
871{
872 const int file = 0;
873
874 VM_BUG_ON_PAGE(!PageHead(page), page);
875 VM_BUG_ON_PAGE(PageCompound(page_tail), page);
876 VM_BUG_ON_PAGE(PageLRU(page_tail), page);
877 lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
878
879 if (!list)
880 SetPageLRU(page_tail);
881
882 if (likely(PageLRU(page)))
883 list_add_tail(&page_tail->lru, &page->lru);
884 else if (list) {
885 /* page reclaim is reclaiming a huge page */
886 get_page(page_tail);
887 list_add_tail(&page_tail->lru, list);
888 } else {
889 /*
890 * Head page has not yet been counted, as an hpage,
891 * so we must account for each subpage individually.
892 *
893 * Put page_tail on the list at the correct position
894 * so they all end up in order.
895 */
896 add_page_to_lru_list_tail(page_tail, lruvec,
897 page_lru(page_tail));
898 }
899
900 if (!PageUnevictable(page))
901 update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
902}
903#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
904
905static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
906 void *arg)
907{
908 enum lru_list lru;
909 int was_unevictable = TestClearPageUnevictable(page);
910
911 VM_BUG_ON_PAGE(PageLRU(page), page);
912
913 SetPageLRU(page);
914 /*
915 * Page becomes evictable in two ways:
916 * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()].
917 * 2) Before acquiring LRU lock to put the page to correct LRU and then
918 * a) do PageLRU check with lock [check_move_unevictable_pages]
919 * b) do PageLRU check before lock [clear_page_mlock]
920 *
921 * (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need
922 * following strict ordering:
923 *
924 * #0: __pagevec_lru_add_fn #1: clear_page_mlock
925 *
926 * SetPageLRU() TestClearPageMlocked()
927 * smp_mb() // explicit ordering // above provides strict
928 * // ordering
929 * PageMlocked() PageLRU()
930 *
931 *
932 * if '#1' does not observe setting of PG_lru by '#0' and fails
933 * isolation, the explicit barrier will make sure that page_evictable
934 * check will put the page in correct LRU. Without smp_mb(), SetPageLRU
935 * can be reordered after PageMlocked check and can make '#1' to fail
936 * the isolation of the page whose Mlocked bit is cleared (#0 is also
937 * looking at the same page) and the evictable page will be stranded
938 * in an unevictable LRU.
939 */
940 smp_mb();
941
942 if (page_evictable(page)) {
943 lru = page_lru(page);
944 update_page_reclaim_stat(lruvec, page_is_file_cache(page),
945 PageActive(page));
946 if (was_unevictable)
947 count_vm_event(UNEVICTABLE_PGRESCUED);
948 } else {
949 lru = LRU_UNEVICTABLE;
950 ClearPageActive(page);
951 SetPageUnevictable(page);
952 if (!was_unevictable)
953 count_vm_event(UNEVICTABLE_PGCULLED);
954 }
955
956 add_page_to_lru_list(page, lruvec, lru);
957 trace_mm_lru_insertion(page, lru);
958}
959
960/*
961 * Add the passed pages to the LRU, then drop the caller's refcount
962 * on them. Reinitialises the caller's pagevec.
963 */
964void __pagevec_lru_add(struct pagevec *pvec)
965{
966 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
967}
968EXPORT_SYMBOL(__pagevec_lru_add);
969
970/**
971 * pagevec_lookup_entries - gang pagecache lookup
972 * @pvec: Where the resulting entries are placed
973 * @mapping: The address_space to search
974 * @start: The starting entry index
975 * @nr_entries: The maximum number of pages
976 * @indices: The cache indices corresponding to the entries in @pvec
977 *
978 * pagevec_lookup_entries() will search for and return a group of up
979 * to @nr_pages pages and shadow entries in the mapping. All
980 * entries are placed in @pvec. pagevec_lookup_entries() takes a
981 * reference against actual pages in @pvec.
982 *
983 * The search returns a group of mapping-contiguous entries with
984 * ascending indexes. There may be holes in the indices due to
985 * not-present entries.
986 *
987 * pagevec_lookup_entries() returns the number of entries which were
988 * found.
989 */
990unsigned pagevec_lookup_entries(struct pagevec *pvec,
991 struct address_space *mapping,
992 pgoff_t start, unsigned nr_entries,
993 pgoff_t *indices)
994{
995 pvec->nr = find_get_entries(mapping, start, nr_entries,
996 pvec->pages, indices);
997 return pagevec_count(pvec);
998}
999
1000/**
1001 * pagevec_remove_exceptionals - pagevec exceptionals pruning
1002 * @pvec: The pagevec to prune
1003 *
1004 * pagevec_lookup_entries() fills both pages and exceptional radix
1005 * tree entries into the pagevec. This function prunes all
1006 * exceptionals from @pvec without leaving holes, so that it can be
1007 * passed on to page-only pagevec operations.
1008 */
1009void pagevec_remove_exceptionals(struct pagevec *pvec)
1010{
1011 int i, j;
1012
1013 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
1014 struct page *page = pvec->pages[i];
1015 if (!xa_is_value(page))
1016 pvec->pages[j++] = page;
1017 }
1018 pvec->nr = j;
1019}
1020
1021/**
1022 * pagevec_lookup_range - gang pagecache lookup
1023 * @pvec: Where the resulting pages are placed
1024 * @mapping: The address_space to search
1025 * @start: The starting page index
1026 * @end: The final page index
1027 *
1028 * pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE
1029 * pages in the mapping starting from index @start and upto index @end
1030 * (inclusive). The pages are placed in @pvec. pagevec_lookup() takes a
1031 * reference against the pages in @pvec.
1032 *
1033 * The search returns a group of mapping-contiguous pages with ascending
1034 * indexes. There may be holes in the indices due to not-present pages. We
1035 * also update @start to index the next page for the traversal.
1036 *
1037 * pagevec_lookup_range() returns the number of pages which were found. If this
1038 * number is smaller than PAGEVEC_SIZE, the end of specified range has been
1039 * reached.
1040 */
1041unsigned pagevec_lookup_range(struct pagevec *pvec,
1042 struct address_space *mapping, pgoff_t *start, pgoff_t end)
1043{
1044 pvec->nr = find_get_pages_range(mapping, start, end, PAGEVEC_SIZE,
1045 pvec->pages);
1046 return pagevec_count(pvec);
1047}
1048EXPORT_SYMBOL(pagevec_lookup_range);
1049
1050unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
1051 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1052 xa_mark_t tag)
1053{
1054 pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1055 PAGEVEC_SIZE, pvec->pages);
1056 return pagevec_count(pvec);
1057}
1058EXPORT_SYMBOL(pagevec_lookup_range_tag);
1059
1060unsigned pagevec_lookup_range_nr_tag(struct pagevec *pvec,
1061 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1062 xa_mark_t tag, unsigned max_pages)
1063{
1064 pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1065 min_t(unsigned int, max_pages, PAGEVEC_SIZE), pvec->pages);
1066 return pagevec_count(pvec);
1067}
1068EXPORT_SYMBOL(pagevec_lookup_range_nr_tag);
1069/*
1070 * Perform any setup for the swap system
1071 */
1072void __init swap_setup(void)
1073{
1074 unsigned long megs = totalram_pages() >> (20 - PAGE_SHIFT);
1075
1076 /* Use a smaller cluster for small-memory machines */
1077 if (megs < 16)
1078 page_cluster = 2;
1079 else
1080 page_cluster = 3;
1081 /*
1082 * Right now other parts of the system means that we
1083 * _really_ don't want to cluster much more
1084 */
1085}