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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#include <linux/local_lock.h>
39
40#include "internal.h"
41
42#define CREATE_TRACE_POINTS
43#include <trace/events/pagemap.h>
44
45/* How many pages do we try to swap or page in/out together? */
46int page_cluster;
47
48/* Protecting only lru_rotate.pvec which requires disabling interrupts */
49struct lru_rotate {
50 local_lock_t lock;
51 struct pagevec pvec;
52};
53static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = {
54 .lock = INIT_LOCAL_LOCK(lock),
55};
56
57/*
58 * The following struct pagevec are grouped together because they are protected
59 * by disabling preemption (and interrupts remain enabled).
60 */
61struct lru_pvecs {
62 local_lock_t lock;
63 struct pagevec lru_add;
64 struct pagevec lru_deactivate_file;
65 struct pagevec lru_deactivate;
66 struct pagevec lru_lazyfree;
67#ifdef CONFIG_SMP
68 struct pagevec activate_page;
69#endif
70};
71static DEFINE_PER_CPU(struct lru_pvecs, lru_pvecs) = {
72 .lock = INIT_LOCAL_LOCK(lock),
73};
74
75/*
76 * This path almost never happens for VM activity - pages are normally
77 * freed via pagevecs. But it gets used by networking.
78 */
79static void __page_cache_release(struct page *page)
80{
81 if (PageLRU(page)) {
82 pg_data_t *pgdat = page_pgdat(page);
83 struct lruvec *lruvec;
84 unsigned long flags;
85
86 spin_lock_irqsave(&pgdat->lru_lock, flags);
87 lruvec = mem_cgroup_page_lruvec(page, pgdat);
88 VM_BUG_ON_PAGE(!PageLRU(page), page);
89 __ClearPageLRU(page);
90 del_page_from_lru_list(page, lruvec, page_off_lru(page));
91 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
92 }
93 __ClearPageWaiters(page);
94}
95
96static void __put_single_page(struct page *page)
97{
98 __page_cache_release(page);
99 mem_cgroup_uncharge(page);
100 free_unref_page(page);
101}
102
103static void __put_compound_page(struct page *page)
104{
105 /*
106 * __page_cache_release() is supposed to be called for thp, not for
107 * hugetlb. This is because hugetlb page does never have PageLRU set
108 * (it's never listed to any LRU lists) and no memcg routines should
109 * be called for hugetlb (it has a separate hugetlb_cgroup.)
110 */
111 if (!PageHuge(page))
112 __page_cache_release(page);
113 destroy_compound_page(page);
114}
115
116void __put_page(struct page *page)
117{
118 if (is_zone_device_page(page)) {
119 put_dev_pagemap(page->pgmap);
120
121 /*
122 * The page belongs to the device that created pgmap. Do
123 * not return it to page allocator.
124 */
125 return;
126 }
127
128 if (unlikely(PageCompound(page)))
129 __put_compound_page(page);
130 else
131 __put_single_page(page);
132}
133EXPORT_SYMBOL(__put_page);
134
135/**
136 * put_pages_list() - release a list of pages
137 * @pages: list of pages threaded on page->lru
138 *
139 * Release a list of pages which are strung together on page.lru. Currently
140 * used by read_cache_pages() and related error recovery code.
141 */
142void put_pages_list(struct list_head *pages)
143{
144 while (!list_empty(pages)) {
145 struct page *victim;
146
147 victim = lru_to_page(pages);
148 list_del(&victim->lru);
149 put_page(victim);
150 }
151}
152EXPORT_SYMBOL(put_pages_list);
153
154/*
155 * get_kernel_pages() - pin kernel pages in memory
156 * @kiov: An array of struct kvec structures
157 * @nr_segs: number of segments to pin
158 * @write: pinning for read/write, currently ignored
159 * @pages: array that receives pointers to the pages pinned.
160 * Should be at least nr_segs long.
161 *
162 * Returns number of pages pinned. This may be fewer than the number
163 * requested. If nr_pages is 0 or negative, returns 0. If no pages
164 * were pinned, returns -errno. Each page returned must be released
165 * with a put_page() call when it is finished with.
166 */
167int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
168 struct page **pages)
169{
170 int seg;
171
172 for (seg = 0; seg < nr_segs; seg++) {
173 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
174 return seg;
175
176 pages[seg] = kmap_to_page(kiov[seg].iov_base);
177 get_page(pages[seg]);
178 }
179
180 return seg;
181}
182EXPORT_SYMBOL_GPL(get_kernel_pages);
183
184/*
185 * get_kernel_page() - pin a kernel page in memory
186 * @start: starting kernel address
187 * @write: pinning for read/write, currently ignored
188 * @pages: array that receives pointer to the page pinned.
189 * Must be at least nr_segs long.
190 *
191 * Returns 1 if page is pinned. If the page was not pinned, returns
192 * -errno. The page returned must be released with a put_page() call
193 * when it is finished with.
194 */
195int get_kernel_page(unsigned long start, int write, struct page **pages)
196{
197 const struct kvec kiov = {
198 .iov_base = (void *)start,
199 .iov_len = PAGE_SIZE
200 };
201
202 return get_kernel_pages(&kiov, 1, write, pages);
203}
204EXPORT_SYMBOL_GPL(get_kernel_page);
205
206static void pagevec_lru_move_fn(struct pagevec *pvec,
207 void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
208 void *arg)
209{
210 int i;
211 struct pglist_data *pgdat = NULL;
212 struct lruvec *lruvec;
213 unsigned long flags = 0;
214
215 for (i = 0; i < pagevec_count(pvec); i++) {
216 struct page *page = pvec->pages[i];
217 struct pglist_data *pagepgdat = page_pgdat(page);
218
219 if (pagepgdat != pgdat) {
220 if (pgdat)
221 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
222 pgdat = pagepgdat;
223 spin_lock_irqsave(&pgdat->lru_lock, flags);
224 }
225
226 lruvec = mem_cgroup_page_lruvec(page, pgdat);
227 (*move_fn)(page, lruvec, arg);
228 }
229 if (pgdat)
230 spin_unlock_irqrestore(&pgdat->lru_lock, flags);
231 release_pages(pvec->pages, pvec->nr);
232 pagevec_reinit(pvec);
233}
234
235static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
236 void *arg)
237{
238 int *pgmoved = arg;
239
240 if (PageLRU(page) && !PageUnevictable(page)) {
241 del_page_from_lru_list(page, lruvec, page_lru(page));
242 ClearPageActive(page);
243 add_page_to_lru_list_tail(page, lruvec, page_lru(page));
244 (*pgmoved) += thp_nr_pages(page);
245 }
246}
247
248/*
249 * pagevec_move_tail() must be called with IRQ disabled.
250 * Otherwise this may cause nasty races.
251 */
252static void pagevec_move_tail(struct pagevec *pvec)
253{
254 int pgmoved = 0;
255
256 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
257 __count_vm_events(PGROTATED, pgmoved);
258}
259
260/*
261 * Writeback is about to end against a page which has been marked for immediate
262 * reclaim. If it still appears to be reclaimable, move it to the tail of the
263 * inactive list.
264 */
265void rotate_reclaimable_page(struct page *page)
266{
267 if (!PageLocked(page) && !PageDirty(page) &&
268 !PageUnevictable(page) && PageLRU(page)) {
269 struct pagevec *pvec;
270 unsigned long flags;
271
272 get_page(page);
273 local_lock_irqsave(&lru_rotate.lock, flags);
274 pvec = this_cpu_ptr(&lru_rotate.pvec);
275 if (!pagevec_add(pvec, page) || PageCompound(page))
276 pagevec_move_tail(pvec);
277 local_unlock_irqrestore(&lru_rotate.lock, flags);
278 }
279}
280
281void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages)
282{
283 do {
284 unsigned long lrusize;
285
286 /* Record cost event */
287 if (file)
288 lruvec->file_cost += nr_pages;
289 else
290 lruvec->anon_cost += nr_pages;
291
292 /*
293 * Decay previous events
294 *
295 * Because workloads change over time (and to avoid
296 * overflow) we keep these statistics as a floating
297 * average, which ends up weighing recent refaults
298 * more than old ones.
299 */
300 lrusize = lruvec_page_state(lruvec, NR_INACTIVE_ANON) +
301 lruvec_page_state(lruvec, NR_ACTIVE_ANON) +
302 lruvec_page_state(lruvec, NR_INACTIVE_FILE) +
303 lruvec_page_state(lruvec, NR_ACTIVE_FILE);
304
305 if (lruvec->file_cost + lruvec->anon_cost > lrusize / 4) {
306 lruvec->file_cost /= 2;
307 lruvec->anon_cost /= 2;
308 }
309 } while ((lruvec = parent_lruvec(lruvec)));
310}
311
312void lru_note_cost_page(struct page *page)
313{
314 lru_note_cost(mem_cgroup_page_lruvec(page, page_pgdat(page)),
315 page_is_file_lru(page), thp_nr_pages(page));
316}
317
318static void __activate_page(struct page *page, struct lruvec *lruvec,
319 void *arg)
320{
321 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
322 int lru = page_lru_base_type(page);
323 int nr_pages = thp_nr_pages(page);
324
325 del_page_from_lru_list(page, lruvec, lru);
326 SetPageActive(page);
327 lru += LRU_ACTIVE;
328 add_page_to_lru_list(page, lruvec, lru);
329 trace_mm_lru_activate(page);
330
331 __count_vm_events(PGACTIVATE, nr_pages);
332 __count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE,
333 nr_pages);
334 }
335}
336
337#ifdef CONFIG_SMP
338static void activate_page_drain(int cpu)
339{
340 struct pagevec *pvec = &per_cpu(lru_pvecs.activate_page, cpu);
341
342 if (pagevec_count(pvec))
343 pagevec_lru_move_fn(pvec, __activate_page, NULL);
344}
345
346static bool need_activate_page_drain(int cpu)
347{
348 return pagevec_count(&per_cpu(lru_pvecs.activate_page, cpu)) != 0;
349}
350
351void activate_page(struct page *page)
352{
353 page = compound_head(page);
354 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
355 struct pagevec *pvec;
356
357 local_lock(&lru_pvecs.lock);
358 pvec = this_cpu_ptr(&lru_pvecs.activate_page);
359 get_page(page);
360 if (!pagevec_add(pvec, page) || PageCompound(page))
361 pagevec_lru_move_fn(pvec, __activate_page, NULL);
362 local_unlock(&lru_pvecs.lock);
363 }
364}
365
366#else
367static inline void activate_page_drain(int cpu)
368{
369}
370
371void activate_page(struct page *page)
372{
373 pg_data_t *pgdat = page_pgdat(page);
374
375 page = compound_head(page);
376 spin_lock_irq(&pgdat->lru_lock);
377 __activate_page(page, mem_cgroup_page_lruvec(page, pgdat), NULL);
378 spin_unlock_irq(&pgdat->lru_lock);
379}
380#endif
381
382static void __lru_cache_activate_page(struct page *page)
383{
384 struct pagevec *pvec;
385 int i;
386
387 local_lock(&lru_pvecs.lock);
388 pvec = this_cpu_ptr(&lru_pvecs.lru_add);
389
390 /*
391 * Search backwards on the optimistic assumption that the page being
392 * activated has just been added to this pagevec. Note that only
393 * the local pagevec is examined as a !PageLRU page could be in the
394 * process of being released, reclaimed, migrated or on a remote
395 * pagevec that is currently being drained. Furthermore, marking
396 * a remote pagevec's page PageActive potentially hits a race where
397 * a page is marked PageActive just after it is added to the inactive
398 * list causing accounting errors and BUG_ON checks to trigger.
399 */
400 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
401 struct page *pagevec_page = pvec->pages[i];
402
403 if (pagevec_page == page) {
404 SetPageActive(page);
405 break;
406 }
407 }
408
409 local_unlock(&lru_pvecs.lock);
410}
411
412/*
413 * Mark a page as having seen activity.
414 *
415 * inactive,unreferenced -> inactive,referenced
416 * inactive,referenced -> active,unreferenced
417 * active,unreferenced -> active,referenced
418 *
419 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
420 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
421 */
422void mark_page_accessed(struct page *page)
423{
424 page = compound_head(page);
425
426 if (!PageReferenced(page)) {
427 SetPageReferenced(page);
428 } else if (PageUnevictable(page)) {
429 /*
430 * Unevictable pages are on the "LRU_UNEVICTABLE" list. But,
431 * this list is never rotated or maintained, so marking an
432 * evictable page accessed has no effect.
433 */
434 } else if (!PageActive(page)) {
435 /*
436 * If the page is on the LRU, queue it for activation via
437 * lru_pvecs.activate_page. Otherwise, assume the page is on a
438 * pagevec, mark it active and it'll be moved to the active
439 * LRU on the next drain.
440 */
441 if (PageLRU(page))
442 activate_page(page);
443 else
444 __lru_cache_activate_page(page);
445 ClearPageReferenced(page);
446 workingset_activation(page);
447 }
448 if (page_is_idle(page))
449 clear_page_idle(page);
450}
451EXPORT_SYMBOL(mark_page_accessed);
452
453/**
454 * lru_cache_add - add a page to a page list
455 * @page: the page to be added to the LRU.
456 *
457 * Queue the page for addition to the LRU via pagevec. The decision on whether
458 * to add the page to the [in]active [file|anon] list is deferred until the
459 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
460 * have the page added to the active list using mark_page_accessed().
461 */
462void lru_cache_add(struct page *page)
463{
464 struct pagevec *pvec;
465
466 VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
467 VM_BUG_ON_PAGE(PageLRU(page), page);
468
469 get_page(page);
470 local_lock(&lru_pvecs.lock);
471 pvec = this_cpu_ptr(&lru_pvecs.lru_add);
472 if (!pagevec_add(pvec, page) || PageCompound(page))
473 __pagevec_lru_add(pvec);
474 local_unlock(&lru_pvecs.lock);
475}
476EXPORT_SYMBOL(lru_cache_add);
477
478/**
479 * lru_cache_add_inactive_or_unevictable
480 * @page: the page to be added to LRU
481 * @vma: vma in which page is mapped for determining reclaimability
482 *
483 * Place @page on the inactive or unevictable LRU list, depending on its
484 * evictability. Note that if the page is not evictable, it goes
485 * directly back onto it's zone's unevictable list, it does NOT use a
486 * per cpu pagevec.
487 */
488void lru_cache_add_inactive_or_unevictable(struct page *page,
489 struct vm_area_struct *vma)
490{
491 bool unevictable;
492
493 VM_BUG_ON_PAGE(PageLRU(page), page);
494
495 unevictable = (vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED;
496 if (unlikely(unevictable) && !TestSetPageMlocked(page)) {
497 int nr_pages = thp_nr_pages(page);
498 /*
499 * We use the irq-unsafe __mod_zone_page_stat because this
500 * counter is not modified from interrupt context, and the pte
501 * lock is held(spinlock), which implies preemption disabled.
502 */
503 __mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);
504 count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
505 }
506 lru_cache_add(page);
507}
508
509/*
510 * If the page can not be invalidated, it is moved to the
511 * inactive list to speed up its reclaim. It is moved to the
512 * head of the list, rather than the tail, to give the flusher
513 * threads some time to write it out, as this is much more
514 * effective than the single-page writeout from reclaim.
515 *
516 * If the page isn't page_mapped and dirty/writeback, the page
517 * could reclaim asap using PG_reclaim.
518 *
519 * 1. active, mapped page -> none
520 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
521 * 3. inactive, mapped page -> none
522 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
523 * 5. inactive, clean -> inactive, tail
524 * 6. Others -> none
525 *
526 * In 4, why it moves inactive's head, the VM expects the page would
527 * be write it out by flusher threads as this is much more effective
528 * than the single-page writeout from reclaim.
529 */
530static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec,
531 void *arg)
532{
533 int lru;
534 bool active;
535 int nr_pages = thp_nr_pages(page);
536
537 if (!PageLRU(page))
538 return;
539
540 if (PageUnevictable(page))
541 return;
542
543 /* Some processes are using the page */
544 if (page_mapped(page))
545 return;
546
547 active = PageActive(page);
548 lru = page_lru_base_type(page);
549
550 del_page_from_lru_list(page, lruvec, lru + active);
551 ClearPageActive(page);
552 ClearPageReferenced(page);
553
554 if (PageWriteback(page) || PageDirty(page)) {
555 /*
556 * PG_reclaim could be raced with end_page_writeback
557 * It can make readahead confusing. But race window
558 * is _really_ small and it's non-critical problem.
559 */
560 add_page_to_lru_list(page, lruvec, lru);
561 SetPageReclaim(page);
562 } else {
563 /*
564 * The page's writeback ends up during pagevec
565 * We moves tha page into tail of inactive.
566 */
567 add_page_to_lru_list_tail(page, lruvec, lru);
568 __count_vm_events(PGROTATED, nr_pages);
569 }
570
571 if (active) {
572 __count_vm_events(PGDEACTIVATE, nr_pages);
573 __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
574 nr_pages);
575 }
576}
577
578static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
579 void *arg)
580{
581 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
582 int lru = page_lru_base_type(page);
583 int nr_pages = thp_nr_pages(page);
584
585 del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
586 ClearPageActive(page);
587 ClearPageReferenced(page);
588 add_page_to_lru_list(page, lruvec, lru);
589
590 __count_vm_events(PGDEACTIVATE, nr_pages);
591 __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
592 nr_pages);
593 }
594}
595
596static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec,
597 void *arg)
598{
599 if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
600 !PageSwapCache(page) && !PageUnevictable(page)) {
601 bool active = PageActive(page);
602 int nr_pages = thp_nr_pages(page);
603
604 del_page_from_lru_list(page, lruvec,
605 LRU_INACTIVE_ANON + active);
606 ClearPageActive(page);
607 ClearPageReferenced(page);
608 /*
609 * Lazyfree pages are clean anonymous pages. They have
610 * PG_swapbacked flag cleared, to distinguish them from normal
611 * anonymous pages
612 */
613 ClearPageSwapBacked(page);
614 add_page_to_lru_list(page, lruvec, LRU_INACTIVE_FILE);
615
616 __count_vm_events(PGLAZYFREE, nr_pages);
617 __count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE,
618 nr_pages);
619 }
620}
621
622/*
623 * Drain pages out of the cpu's pagevecs.
624 * Either "cpu" is the current CPU, and preemption has already been
625 * disabled; or "cpu" is being hot-unplugged, and is already dead.
626 */
627void lru_add_drain_cpu(int cpu)
628{
629 struct pagevec *pvec = &per_cpu(lru_pvecs.lru_add, cpu);
630
631 if (pagevec_count(pvec))
632 __pagevec_lru_add(pvec);
633
634 pvec = &per_cpu(lru_rotate.pvec, cpu);
635 /* Disabling interrupts below acts as a compiler barrier. */
636 if (data_race(pagevec_count(pvec))) {
637 unsigned long flags;
638
639 /* No harm done if a racing interrupt already did this */
640 local_lock_irqsave(&lru_rotate.lock, flags);
641 pagevec_move_tail(pvec);
642 local_unlock_irqrestore(&lru_rotate.lock, flags);
643 }
644
645 pvec = &per_cpu(lru_pvecs.lru_deactivate_file, cpu);
646 if (pagevec_count(pvec))
647 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
648
649 pvec = &per_cpu(lru_pvecs.lru_deactivate, cpu);
650 if (pagevec_count(pvec))
651 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
652
653 pvec = &per_cpu(lru_pvecs.lru_lazyfree, cpu);
654 if (pagevec_count(pvec))
655 pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
656
657 activate_page_drain(cpu);
658}
659
660/**
661 * deactivate_file_page - forcefully deactivate a file page
662 * @page: page to deactivate
663 *
664 * This function hints the VM that @page is a good reclaim candidate,
665 * for example if its invalidation fails due to the page being dirty
666 * or under writeback.
667 */
668void deactivate_file_page(struct page *page)
669{
670 /*
671 * In a workload with many unevictable page such as mprotect,
672 * unevictable page deactivation for accelerating reclaim is pointless.
673 */
674 if (PageUnevictable(page))
675 return;
676
677 if (likely(get_page_unless_zero(page))) {
678 struct pagevec *pvec;
679
680 local_lock(&lru_pvecs.lock);
681 pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate_file);
682
683 if (!pagevec_add(pvec, page) || PageCompound(page))
684 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
685 local_unlock(&lru_pvecs.lock);
686 }
687}
688
689/*
690 * deactivate_page - deactivate a page
691 * @page: page to deactivate
692 *
693 * deactivate_page() moves @page to the inactive list if @page was on the active
694 * list and was not an unevictable page. This is done to accelerate the reclaim
695 * of @page.
696 */
697void deactivate_page(struct page *page)
698{
699 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
700 struct pagevec *pvec;
701
702 local_lock(&lru_pvecs.lock);
703 pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate);
704 get_page(page);
705 if (!pagevec_add(pvec, page) || PageCompound(page))
706 pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
707 local_unlock(&lru_pvecs.lock);
708 }
709}
710
711/**
712 * mark_page_lazyfree - make an anon page lazyfree
713 * @page: page to deactivate
714 *
715 * mark_page_lazyfree() moves @page to the inactive file list.
716 * This is done to accelerate the reclaim of @page.
717 */
718void mark_page_lazyfree(struct page *page)
719{
720 if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
721 !PageSwapCache(page) && !PageUnevictable(page)) {
722 struct pagevec *pvec;
723
724 local_lock(&lru_pvecs.lock);
725 pvec = this_cpu_ptr(&lru_pvecs.lru_lazyfree);
726 get_page(page);
727 if (!pagevec_add(pvec, page) || PageCompound(page))
728 pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
729 local_unlock(&lru_pvecs.lock);
730 }
731}
732
733void lru_add_drain(void)
734{
735 local_lock(&lru_pvecs.lock);
736 lru_add_drain_cpu(smp_processor_id());
737 local_unlock(&lru_pvecs.lock);
738}
739
740void lru_add_drain_cpu_zone(struct zone *zone)
741{
742 local_lock(&lru_pvecs.lock);
743 lru_add_drain_cpu(smp_processor_id());
744 drain_local_pages(zone);
745 local_unlock(&lru_pvecs.lock);
746}
747
748#ifdef CONFIG_SMP
749
750static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
751
752static void lru_add_drain_per_cpu(struct work_struct *dummy)
753{
754 lru_add_drain();
755}
756
757/*
758 * Doesn't need any cpu hotplug locking because we do rely on per-cpu
759 * kworkers being shut down before our page_alloc_cpu_dead callback is
760 * executed on the offlined cpu.
761 * Calling this function with cpu hotplug locks held can actually lead
762 * to obscure indirect dependencies via WQ context.
763 */
764void lru_add_drain_all(void)
765{
766 static seqcount_t seqcount = SEQCNT_ZERO(seqcount);
767 static DEFINE_MUTEX(lock);
768 static struct cpumask has_work;
769 int cpu, seq;
770
771 /*
772 * Make sure nobody triggers this path before mm_percpu_wq is fully
773 * initialized.
774 */
775 if (WARN_ON(!mm_percpu_wq))
776 return;
777
778 seq = raw_read_seqcount_latch(&seqcount);
779
780 mutex_lock(&lock);
781
782 /*
783 * Piggyback on drain started and finished while we waited for lock:
784 * all pages pended at the time of our enter were drained from vectors.
785 */
786 if (__read_seqcount_retry(&seqcount, seq))
787 goto done;
788
789 raw_write_seqcount_latch(&seqcount);
790
791 cpumask_clear(&has_work);
792
793 for_each_online_cpu(cpu) {
794 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
795
796 if (pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||
797 data_race(pagevec_count(&per_cpu(lru_rotate.pvec, cpu))) ||
798 pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) ||
799 pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) ||
800 pagevec_count(&per_cpu(lru_pvecs.lru_lazyfree, cpu)) ||
801 need_activate_page_drain(cpu)) {
802 INIT_WORK(work, lru_add_drain_per_cpu);
803 queue_work_on(cpu, mm_percpu_wq, work);
804 cpumask_set_cpu(cpu, &has_work);
805 }
806 }
807
808 for_each_cpu(cpu, &has_work)
809 flush_work(&per_cpu(lru_add_drain_work, cpu));
810
811done:
812 mutex_unlock(&lock);
813}
814#else
815void lru_add_drain_all(void)
816{
817 lru_add_drain();
818}
819#endif
820
821/**
822 * release_pages - batched put_page()
823 * @pages: array of pages to release
824 * @nr: number of pages
825 *
826 * Decrement the reference count on all the pages in @pages. If it
827 * fell to zero, remove the page from the LRU and free it.
828 */
829void release_pages(struct page **pages, int nr)
830{
831 int i;
832 LIST_HEAD(pages_to_free);
833 struct pglist_data *locked_pgdat = NULL;
834 struct lruvec *lruvec;
835 unsigned long flags;
836 unsigned int lock_batch;
837
838 for (i = 0; i < nr; i++) {
839 struct page *page = pages[i];
840
841 /*
842 * Make sure the IRQ-safe lock-holding time does not get
843 * excessive with a continuous string of pages from the
844 * same pgdat. The lock is held only if pgdat != NULL.
845 */
846 if (locked_pgdat && ++lock_batch == SWAP_CLUSTER_MAX) {
847 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
848 locked_pgdat = NULL;
849 }
850
851 if (is_huge_zero_page(page))
852 continue;
853
854 if (is_zone_device_page(page)) {
855 if (locked_pgdat) {
856 spin_unlock_irqrestore(&locked_pgdat->lru_lock,
857 flags);
858 locked_pgdat = NULL;
859 }
860 /*
861 * ZONE_DEVICE pages that return 'false' from
862 * put_devmap_managed_page() do not require special
863 * processing, and instead, expect a call to
864 * put_page_testzero().
865 */
866 if (page_is_devmap_managed(page)) {
867 put_devmap_managed_page(page);
868 continue;
869 }
870 }
871
872 page = compound_head(page);
873 if (!put_page_testzero(page))
874 continue;
875
876 if (PageCompound(page)) {
877 if (locked_pgdat) {
878 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
879 locked_pgdat = NULL;
880 }
881 __put_compound_page(page);
882 continue;
883 }
884
885 if (PageLRU(page)) {
886 struct pglist_data *pgdat = page_pgdat(page);
887
888 if (pgdat != locked_pgdat) {
889 if (locked_pgdat)
890 spin_unlock_irqrestore(&locked_pgdat->lru_lock,
891 flags);
892 lock_batch = 0;
893 locked_pgdat = pgdat;
894 spin_lock_irqsave(&locked_pgdat->lru_lock, flags);
895 }
896
897 lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
898 VM_BUG_ON_PAGE(!PageLRU(page), page);
899 __ClearPageLRU(page);
900 del_page_from_lru_list(page, lruvec, page_off_lru(page));
901 }
902
903 /* Clear Active bit in case of parallel mark_page_accessed */
904 __ClearPageActive(page);
905 __ClearPageWaiters(page);
906
907 list_add(&page->lru, &pages_to_free);
908 }
909 if (locked_pgdat)
910 spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
911
912 mem_cgroup_uncharge_list(&pages_to_free);
913 free_unref_page_list(&pages_to_free);
914}
915EXPORT_SYMBOL(release_pages);
916
917/*
918 * The pages which we're about to release may be in the deferred lru-addition
919 * queues. That would prevent them from really being freed right now. That's
920 * OK from a correctness point of view but is inefficient - those pages may be
921 * cache-warm and we want to give them back to the page allocator ASAP.
922 *
923 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
924 * and __pagevec_lru_add_active() call release_pages() directly to avoid
925 * mutual recursion.
926 */
927void __pagevec_release(struct pagevec *pvec)
928{
929 if (!pvec->percpu_pvec_drained) {
930 lru_add_drain();
931 pvec->percpu_pvec_drained = true;
932 }
933 release_pages(pvec->pages, pagevec_count(pvec));
934 pagevec_reinit(pvec);
935}
936EXPORT_SYMBOL(__pagevec_release);
937
938#ifdef CONFIG_TRANSPARENT_HUGEPAGE
939/* used by __split_huge_page_refcount() */
940void lru_add_page_tail(struct page *page, struct page *page_tail,
941 struct lruvec *lruvec, struct list_head *list)
942{
943 VM_BUG_ON_PAGE(!PageHead(page), page);
944 VM_BUG_ON_PAGE(PageCompound(page_tail), page);
945 VM_BUG_ON_PAGE(PageLRU(page_tail), page);
946 lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
947
948 if (!list)
949 SetPageLRU(page_tail);
950
951 if (likely(PageLRU(page)))
952 list_add_tail(&page_tail->lru, &page->lru);
953 else if (list) {
954 /* page reclaim is reclaiming a huge page */
955 get_page(page_tail);
956 list_add_tail(&page_tail->lru, list);
957 } else {
958 /*
959 * Head page has not yet been counted, as an hpage,
960 * so we must account for each subpage individually.
961 *
962 * Put page_tail on the list at the correct position
963 * so they all end up in order.
964 */
965 add_page_to_lru_list_tail(page_tail, lruvec,
966 page_lru(page_tail));
967 }
968}
969#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
970
971static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
972 void *arg)
973{
974 enum lru_list lru;
975 int was_unevictable = TestClearPageUnevictable(page);
976 int nr_pages = thp_nr_pages(page);
977
978 VM_BUG_ON_PAGE(PageLRU(page), page);
979
980 /*
981 * Page becomes evictable in two ways:
982 * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()].
983 * 2) Before acquiring LRU lock to put the page to correct LRU and then
984 * a) do PageLRU check with lock [check_move_unevictable_pages]
985 * b) do PageLRU check before lock [clear_page_mlock]
986 *
987 * (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need
988 * following strict ordering:
989 *
990 * #0: __pagevec_lru_add_fn #1: clear_page_mlock
991 *
992 * SetPageLRU() TestClearPageMlocked()
993 * smp_mb() // explicit ordering // above provides strict
994 * // ordering
995 * PageMlocked() PageLRU()
996 *
997 *
998 * if '#1' does not observe setting of PG_lru by '#0' and fails
999 * isolation, the explicit barrier will make sure that page_evictable
1000 * check will put the page in correct LRU. Without smp_mb(), SetPageLRU
1001 * can be reordered after PageMlocked check and can make '#1' to fail
1002 * the isolation of the page whose Mlocked bit is cleared (#0 is also
1003 * looking at the same page) and the evictable page will be stranded
1004 * in an unevictable LRU.
1005 */
1006 SetPageLRU(page);
1007 smp_mb__after_atomic();
1008
1009 if (page_evictable(page)) {
1010 lru = page_lru(page);
1011 if (was_unevictable)
1012 __count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages);
1013 } else {
1014 lru = LRU_UNEVICTABLE;
1015 ClearPageActive(page);
1016 SetPageUnevictable(page);
1017 if (!was_unevictable)
1018 __count_vm_events(UNEVICTABLE_PGCULLED, nr_pages);
1019 }
1020
1021 add_page_to_lru_list(page, lruvec, lru);
1022 trace_mm_lru_insertion(page, lru);
1023}
1024
1025/*
1026 * Add the passed pages to the LRU, then drop the caller's refcount
1027 * on them. Reinitialises the caller's pagevec.
1028 */
1029void __pagevec_lru_add(struct pagevec *pvec)
1030{
1031 pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
1032}
1033
1034/**
1035 * pagevec_lookup_entries - gang pagecache lookup
1036 * @pvec: Where the resulting entries are placed
1037 * @mapping: The address_space to search
1038 * @start: The starting entry index
1039 * @nr_entries: The maximum number of pages
1040 * @indices: The cache indices corresponding to the entries in @pvec
1041 *
1042 * pagevec_lookup_entries() will search for and return a group of up
1043 * to @nr_pages pages and shadow entries in the mapping. All
1044 * entries are placed in @pvec. pagevec_lookup_entries() takes a
1045 * reference against actual pages in @pvec.
1046 *
1047 * The search returns a group of mapping-contiguous entries with
1048 * ascending indexes. There may be holes in the indices due to
1049 * not-present entries.
1050 *
1051 * Only one subpage of a Transparent Huge Page is returned in one call:
1052 * allowing truncate_inode_pages_range() to evict the whole THP without
1053 * cycling through a pagevec of extra references.
1054 *
1055 * pagevec_lookup_entries() returns the number of entries which were
1056 * found.
1057 */
1058unsigned pagevec_lookup_entries(struct pagevec *pvec,
1059 struct address_space *mapping,
1060 pgoff_t start, unsigned nr_entries,
1061 pgoff_t *indices)
1062{
1063 pvec->nr = find_get_entries(mapping, start, nr_entries,
1064 pvec->pages, indices);
1065 return pagevec_count(pvec);
1066}
1067
1068/**
1069 * pagevec_remove_exceptionals - pagevec exceptionals pruning
1070 * @pvec: The pagevec to prune
1071 *
1072 * pagevec_lookup_entries() fills both pages and exceptional radix
1073 * tree entries into the pagevec. This function prunes all
1074 * exceptionals from @pvec without leaving holes, so that it can be
1075 * passed on to page-only pagevec operations.
1076 */
1077void pagevec_remove_exceptionals(struct pagevec *pvec)
1078{
1079 int i, j;
1080
1081 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
1082 struct page *page = pvec->pages[i];
1083 if (!xa_is_value(page))
1084 pvec->pages[j++] = page;
1085 }
1086 pvec->nr = j;
1087}
1088
1089/**
1090 * pagevec_lookup_range - gang pagecache lookup
1091 * @pvec: Where the resulting pages are placed
1092 * @mapping: The address_space to search
1093 * @start: The starting page index
1094 * @end: The final page index
1095 *
1096 * pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE
1097 * pages in the mapping starting from index @start and upto index @end
1098 * (inclusive). The pages are placed in @pvec. pagevec_lookup() takes a
1099 * reference against the pages in @pvec.
1100 *
1101 * The search returns a group of mapping-contiguous pages with ascending
1102 * indexes. There may be holes in the indices due to not-present pages. We
1103 * also update @start to index the next page for the traversal.
1104 *
1105 * pagevec_lookup_range() returns the number of pages which were found. If this
1106 * number is smaller than PAGEVEC_SIZE, the end of specified range has been
1107 * reached.
1108 */
1109unsigned pagevec_lookup_range(struct pagevec *pvec,
1110 struct address_space *mapping, pgoff_t *start, pgoff_t end)
1111{
1112 pvec->nr = find_get_pages_range(mapping, start, end, PAGEVEC_SIZE,
1113 pvec->pages);
1114 return pagevec_count(pvec);
1115}
1116EXPORT_SYMBOL(pagevec_lookup_range);
1117
1118unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
1119 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1120 xa_mark_t tag)
1121{
1122 pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1123 PAGEVEC_SIZE, pvec->pages);
1124 return pagevec_count(pvec);
1125}
1126EXPORT_SYMBOL(pagevec_lookup_range_tag);
1127
1128unsigned pagevec_lookup_range_nr_tag(struct pagevec *pvec,
1129 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1130 xa_mark_t tag, unsigned max_pages)
1131{
1132 pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1133 min_t(unsigned int, max_pages, PAGEVEC_SIZE), pvec->pages);
1134 return pagevec_count(pvec);
1135}
1136EXPORT_SYMBOL(pagevec_lookup_range_nr_tag);
1137/*
1138 * Perform any setup for the swap system
1139 */
1140void __init swap_setup(void)
1141{
1142 unsigned long megs = totalram_pages() >> (20 - PAGE_SHIFT);
1143
1144 /* Use a smaller cluster for small-memory machines */
1145 if (megs < 16)
1146 page_cluster = 2;
1147 else
1148 page_cluster = 3;
1149 /*
1150 * Right now other parts of the system means that we
1151 * _really_ don't want to cluster much more
1152 */
1153}
1154
1155#ifdef CONFIG_DEV_PAGEMAP_OPS
1156void put_devmap_managed_page(struct page *page)
1157{
1158 int count;
1159
1160 if (WARN_ON_ONCE(!page_is_devmap_managed(page)))
1161 return;
1162
1163 count = page_ref_dec_return(page);
1164
1165 /*
1166 * devmap page refcounts are 1-based, rather than 0-based: if
1167 * refcount is 1, then the page is free and the refcount is
1168 * stable because nobody holds a reference on the page.
1169 */
1170 if (count == 1)
1171 free_devmap_managed_page(page);
1172 else if (!count)
1173 __put_page(page);
1174}
1175EXPORT_SYMBOL(put_devmap_managed_page);
1176#endif
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#include <linux/local_lock.h>
39#include <linux/buffer_head.h>
40
41#include "internal.h"
42
43#define CREATE_TRACE_POINTS
44#include <trace/events/pagemap.h>
45
46/* How many pages do we try to swap or page in/out together? */
47int page_cluster;
48
49/* Protecting only lru_rotate.pvec which requires disabling interrupts */
50struct lru_rotate {
51 local_lock_t lock;
52 struct pagevec pvec;
53};
54static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = {
55 .lock = INIT_LOCAL_LOCK(lock),
56};
57
58/*
59 * The following struct pagevec are grouped together because they are protected
60 * by disabling preemption (and interrupts remain enabled).
61 */
62struct lru_pvecs {
63 local_lock_t lock;
64 struct pagevec lru_add;
65 struct pagevec lru_deactivate_file;
66 struct pagevec lru_deactivate;
67 struct pagevec lru_lazyfree;
68#ifdef CONFIG_SMP
69 struct pagevec activate_page;
70#endif
71};
72static DEFINE_PER_CPU(struct lru_pvecs, lru_pvecs) = {
73 .lock = INIT_LOCAL_LOCK(lock),
74};
75
76/*
77 * This path almost never happens for VM activity - pages are normally
78 * freed via pagevecs. But it gets used by networking.
79 */
80static void __page_cache_release(struct page *page)
81{
82 if (PageLRU(page)) {
83 struct lruvec *lruvec;
84 unsigned long flags;
85
86 lruvec = lock_page_lruvec_irqsave(page, &flags);
87 del_page_from_lru_list(page, lruvec);
88 __clear_page_lru_flags(page);
89 unlock_page_lruvec_irqrestore(lruvec, flags);
90 }
91 __ClearPageWaiters(page);
92}
93
94static void __put_single_page(struct page *page)
95{
96 __page_cache_release(page);
97 mem_cgroup_uncharge(page);
98 free_unref_page(page, 0);
99}
100
101static void __put_compound_page(struct page *page)
102{
103 /*
104 * __page_cache_release() is supposed to be called for thp, not for
105 * hugetlb. This is because hugetlb page does never have PageLRU set
106 * (it's never listed to any LRU lists) and no memcg routines should
107 * be called for hugetlb (it has a separate hugetlb_cgroup.)
108 */
109 if (!PageHuge(page))
110 __page_cache_release(page);
111 destroy_compound_page(page);
112}
113
114void __put_page(struct page *page)
115{
116 if (is_zone_device_page(page)) {
117 put_dev_pagemap(page->pgmap);
118
119 /*
120 * The page belongs to the device that created pgmap. Do
121 * not return it to page allocator.
122 */
123 return;
124 }
125
126 if (unlikely(PageCompound(page)))
127 __put_compound_page(page);
128 else
129 __put_single_page(page);
130}
131EXPORT_SYMBOL(__put_page);
132
133/**
134 * put_pages_list() - release a list of pages
135 * @pages: list of pages threaded on page->lru
136 *
137 * Release a list of pages which are strung together on page.lru. Currently
138 * used by read_cache_pages() and related error recovery code.
139 */
140void put_pages_list(struct list_head *pages)
141{
142 while (!list_empty(pages)) {
143 struct page *victim;
144
145 victim = lru_to_page(pages);
146 list_del(&victim->lru);
147 put_page(victim);
148 }
149}
150EXPORT_SYMBOL(put_pages_list);
151
152/*
153 * get_kernel_pages() - pin kernel pages in memory
154 * @kiov: An array of struct kvec structures
155 * @nr_segs: number of segments to pin
156 * @write: pinning for read/write, currently ignored
157 * @pages: array that receives pointers to the pages pinned.
158 * Should be at least nr_segs long.
159 *
160 * Returns number of pages pinned. This may be fewer than the number
161 * requested. If nr_pages is 0 or negative, returns 0. If no pages
162 * were pinned, returns -errno. Each page returned must be released
163 * with a put_page() call when it is finished with.
164 */
165int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
166 struct page **pages)
167{
168 int seg;
169
170 for (seg = 0; seg < nr_segs; seg++) {
171 if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
172 return seg;
173
174 pages[seg] = kmap_to_page(kiov[seg].iov_base);
175 get_page(pages[seg]);
176 }
177
178 return seg;
179}
180EXPORT_SYMBOL_GPL(get_kernel_pages);
181
182/*
183 * get_kernel_page() - pin a kernel page in memory
184 * @start: starting kernel address
185 * @write: pinning for read/write, currently ignored
186 * @pages: array that receives pointer to the page pinned.
187 * Must be at least nr_segs long.
188 *
189 * Returns 1 if page is pinned. If the page was not pinned, returns
190 * -errno. The page returned must be released with a put_page() call
191 * when it is finished with.
192 */
193int get_kernel_page(unsigned long start, int write, struct page **pages)
194{
195 const struct kvec kiov = {
196 .iov_base = (void *)start,
197 .iov_len = PAGE_SIZE
198 };
199
200 return get_kernel_pages(&kiov, 1, write, pages);
201}
202EXPORT_SYMBOL_GPL(get_kernel_page);
203
204static void pagevec_lru_move_fn(struct pagevec *pvec,
205 void (*move_fn)(struct page *page, struct lruvec *lruvec))
206{
207 int i;
208 struct lruvec *lruvec = NULL;
209 unsigned long flags = 0;
210
211 for (i = 0; i < pagevec_count(pvec); i++) {
212 struct page *page = pvec->pages[i];
213
214 /* block memcg migration during page moving between lru */
215 if (!TestClearPageLRU(page))
216 continue;
217
218 lruvec = relock_page_lruvec_irqsave(page, lruvec, &flags);
219 (*move_fn)(page, lruvec);
220
221 SetPageLRU(page);
222 }
223 if (lruvec)
224 unlock_page_lruvec_irqrestore(lruvec, flags);
225 release_pages(pvec->pages, pvec->nr);
226 pagevec_reinit(pvec);
227}
228
229static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec)
230{
231 if (!PageUnevictable(page)) {
232 del_page_from_lru_list(page, lruvec);
233 ClearPageActive(page);
234 add_page_to_lru_list_tail(page, lruvec);
235 __count_vm_events(PGROTATED, thp_nr_pages(page));
236 }
237}
238
239/* return true if pagevec needs to drain */
240static bool pagevec_add_and_need_flush(struct pagevec *pvec, struct page *page)
241{
242 bool ret = false;
243
244 if (!pagevec_add(pvec, page) || PageCompound(page) ||
245 lru_cache_disabled())
246 ret = true;
247
248 return ret;
249}
250
251/*
252 * Writeback is about to end against a page which has been marked for immediate
253 * reclaim. If it still appears to be reclaimable, move it to the tail of the
254 * inactive list.
255 *
256 * rotate_reclaimable_page() must disable IRQs, to prevent nasty races.
257 */
258void rotate_reclaimable_page(struct page *page)
259{
260 if (!PageLocked(page) && !PageDirty(page) &&
261 !PageUnevictable(page) && PageLRU(page)) {
262 struct pagevec *pvec;
263 unsigned long flags;
264
265 get_page(page);
266 local_lock_irqsave(&lru_rotate.lock, flags);
267 pvec = this_cpu_ptr(&lru_rotate.pvec);
268 if (pagevec_add_and_need_flush(pvec, page))
269 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn);
270 local_unlock_irqrestore(&lru_rotate.lock, flags);
271 }
272}
273
274void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages)
275{
276 do {
277 unsigned long lrusize;
278
279 /*
280 * Hold lruvec->lru_lock is safe here, since
281 * 1) The pinned lruvec in reclaim, or
282 * 2) From a pre-LRU page during refault (which also holds the
283 * rcu lock, so would be safe even if the page was on the LRU
284 * and could move simultaneously to a new lruvec).
285 */
286 spin_lock_irq(&lruvec->lru_lock);
287 /* Record cost event */
288 if (file)
289 lruvec->file_cost += nr_pages;
290 else
291 lruvec->anon_cost += nr_pages;
292
293 /*
294 * Decay previous events
295 *
296 * Because workloads change over time (and to avoid
297 * overflow) we keep these statistics as a floating
298 * average, which ends up weighing recent refaults
299 * more than old ones.
300 */
301 lrusize = lruvec_page_state(lruvec, NR_INACTIVE_ANON) +
302 lruvec_page_state(lruvec, NR_ACTIVE_ANON) +
303 lruvec_page_state(lruvec, NR_INACTIVE_FILE) +
304 lruvec_page_state(lruvec, NR_ACTIVE_FILE);
305
306 if (lruvec->file_cost + lruvec->anon_cost > lrusize / 4) {
307 lruvec->file_cost /= 2;
308 lruvec->anon_cost /= 2;
309 }
310 spin_unlock_irq(&lruvec->lru_lock);
311 } while ((lruvec = parent_lruvec(lruvec)));
312}
313
314void lru_note_cost_page(struct page *page)
315{
316 lru_note_cost(mem_cgroup_page_lruvec(page),
317 page_is_file_lru(page), thp_nr_pages(page));
318}
319
320static void __activate_page(struct page *page, struct lruvec *lruvec)
321{
322 if (!PageActive(page) && !PageUnevictable(page)) {
323 int nr_pages = thp_nr_pages(page);
324
325 del_page_from_lru_list(page, lruvec);
326 SetPageActive(page);
327 add_page_to_lru_list(page, lruvec);
328 trace_mm_lru_activate(page);
329
330 __count_vm_events(PGACTIVATE, nr_pages);
331 __count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE,
332 nr_pages);
333 }
334}
335
336#ifdef CONFIG_SMP
337static void activate_page_drain(int cpu)
338{
339 struct pagevec *pvec = &per_cpu(lru_pvecs.activate_page, cpu);
340
341 if (pagevec_count(pvec))
342 pagevec_lru_move_fn(pvec, __activate_page);
343}
344
345static bool need_activate_page_drain(int cpu)
346{
347 return pagevec_count(&per_cpu(lru_pvecs.activate_page, cpu)) != 0;
348}
349
350static void activate_page(struct page *page)
351{
352 page = compound_head(page);
353 if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
354 struct pagevec *pvec;
355
356 local_lock(&lru_pvecs.lock);
357 pvec = this_cpu_ptr(&lru_pvecs.activate_page);
358 get_page(page);
359 if (pagevec_add_and_need_flush(pvec, page))
360 pagevec_lru_move_fn(pvec, __activate_page);
361 local_unlock(&lru_pvecs.lock);
362 }
363}
364
365#else
366static inline void activate_page_drain(int cpu)
367{
368}
369
370static void activate_page(struct page *page)
371{
372 struct lruvec *lruvec;
373
374 page = compound_head(page);
375 if (TestClearPageLRU(page)) {
376 lruvec = lock_page_lruvec_irq(page);
377 __activate_page(page, lruvec);
378 unlock_page_lruvec_irq(lruvec);
379 SetPageLRU(page);
380 }
381}
382#endif
383
384static void __lru_cache_activate_page(struct page *page)
385{
386 struct pagevec *pvec;
387 int i;
388
389 local_lock(&lru_pvecs.lock);
390 pvec = this_cpu_ptr(&lru_pvecs.lru_add);
391
392 /*
393 * Search backwards on the optimistic assumption that the page being
394 * activated has just been added to this pagevec. Note that only
395 * the local pagevec is examined as a !PageLRU page could be in the
396 * process of being released, reclaimed, migrated or on a remote
397 * pagevec that is currently being drained. Furthermore, marking
398 * a remote pagevec's page PageActive potentially hits a race where
399 * a page is marked PageActive just after it is added to the inactive
400 * list causing accounting errors and BUG_ON checks to trigger.
401 */
402 for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
403 struct page *pagevec_page = pvec->pages[i];
404
405 if (pagevec_page == page) {
406 SetPageActive(page);
407 break;
408 }
409 }
410
411 local_unlock(&lru_pvecs.lock);
412}
413
414/*
415 * Mark a page as having seen activity.
416 *
417 * inactive,unreferenced -> inactive,referenced
418 * inactive,referenced -> active,unreferenced
419 * active,unreferenced -> active,referenced
420 *
421 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
422 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
423 */
424void mark_page_accessed(struct page *page)
425{
426 page = compound_head(page);
427
428 if (!PageReferenced(page)) {
429 SetPageReferenced(page);
430 } else if (PageUnevictable(page)) {
431 /*
432 * Unevictable pages are on the "LRU_UNEVICTABLE" list. But,
433 * this list is never rotated or maintained, so marking an
434 * evictable page accessed has no effect.
435 */
436 } else if (!PageActive(page)) {
437 /*
438 * If the page is on the LRU, queue it for activation via
439 * lru_pvecs.activate_page. Otherwise, assume the page is on a
440 * pagevec, mark it active and it'll be moved to the active
441 * LRU on the next drain.
442 */
443 if (PageLRU(page))
444 activate_page(page);
445 else
446 __lru_cache_activate_page(page);
447 ClearPageReferenced(page);
448 workingset_activation(page);
449 }
450 if (page_is_idle(page))
451 clear_page_idle(page);
452}
453EXPORT_SYMBOL(mark_page_accessed);
454
455/**
456 * lru_cache_add - add a page to a page list
457 * @page: the page to be added to the LRU.
458 *
459 * Queue the page for addition to the LRU via pagevec. The decision on whether
460 * to add the page to the [in]active [file|anon] list is deferred until the
461 * pagevec is drained. This gives a chance for the caller of lru_cache_add()
462 * have the page added to the active list using mark_page_accessed().
463 */
464void lru_cache_add(struct page *page)
465{
466 struct pagevec *pvec;
467
468 VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
469 VM_BUG_ON_PAGE(PageLRU(page), page);
470
471 get_page(page);
472 local_lock(&lru_pvecs.lock);
473 pvec = this_cpu_ptr(&lru_pvecs.lru_add);
474 if (pagevec_add_and_need_flush(pvec, page))
475 __pagevec_lru_add(pvec);
476 local_unlock(&lru_pvecs.lock);
477}
478EXPORT_SYMBOL(lru_cache_add);
479
480/**
481 * lru_cache_add_inactive_or_unevictable
482 * @page: the page to be added to LRU
483 * @vma: vma in which page is mapped for determining reclaimability
484 *
485 * Place @page on the inactive or unevictable LRU list, depending on its
486 * evictability.
487 */
488void lru_cache_add_inactive_or_unevictable(struct page *page,
489 struct vm_area_struct *vma)
490{
491 bool unevictable;
492
493 VM_BUG_ON_PAGE(PageLRU(page), page);
494
495 unevictable = (vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED;
496 if (unlikely(unevictable) && !TestSetPageMlocked(page)) {
497 int nr_pages = thp_nr_pages(page);
498 /*
499 * We use the irq-unsafe __mod_zone_page_state because this
500 * counter is not modified from interrupt context, and the pte
501 * lock is held(spinlock), which implies preemption disabled.
502 */
503 __mod_zone_page_state(page_zone(page), NR_MLOCK, nr_pages);
504 count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages);
505 }
506 lru_cache_add(page);
507}
508
509/*
510 * If the page can not be invalidated, it is moved to the
511 * inactive list to speed up its reclaim. It is moved to the
512 * head of the list, rather than the tail, to give the flusher
513 * threads some time to write it out, as this is much more
514 * effective than the single-page writeout from reclaim.
515 *
516 * If the page isn't page_mapped and dirty/writeback, the page
517 * could reclaim asap using PG_reclaim.
518 *
519 * 1. active, mapped page -> none
520 * 2. active, dirty/writeback page -> inactive, head, PG_reclaim
521 * 3. inactive, mapped page -> none
522 * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
523 * 5. inactive, clean -> inactive, tail
524 * 6. Others -> none
525 *
526 * In 4, why it moves inactive's head, the VM expects the page would
527 * be write it out by flusher threads as this is much more effective
528 * than the single-page writeout from reclaim.
529 */
530static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec)
531{
532 bool active = PageActive(page);
533 int nr_pages = thp_nr_pages(page);
534
535 if (PageUnevictable(page))
536 return;
537
538 /* Some processes are using the page */
539 if (page_mapped(page))
540 return;
541
542 del_page_from_lru_list(page, lruvec);
543 ClearPageActive(page);
544 ClearPageReferenced(page);
545
546 if (PageWriteback(page) || PageDirty(page)) {
547 /*
548 * PG_reclaim could be raced with end_page_writeback
549 * It can make readahead confusing. But race window
550 * is _really_ small and it's non-critical problem.
551 */
552 add_page_to_lru_list(page, lruvec);
553 SetPageReclaim(page);
554 } else {
555 /*
556 * The page's writeback ends up during pagevec
557 * We move that page into tail of inactive.
558 */
559 add_page_to_lru_list_tail(page, lruvec);
560 __count_vm_events(PGROTATED, nr_pages);
561 }
562
563 if (active) {
564 __count_vm_events(PGDEACTIVATE, nr_pages);
565 __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
566 nr_pages);
567 }
568}
569
570static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec)
571{
572 if (PageActive(page) && !PageUnevictable(page)) {
573 int nr_pages = thp_nr_pages(page);
574
575 del_page_from_lru_list(page, lruvec);
576 ClearPageActive(page);
577 ClearPageReferenced(page);
578 add_page_to_lru_list(page, lruvec);
579
580 __count_vm_events(PGDEACTIVATE, nr_pages);
581 __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
582 nr_pages);
583 }
584}
585
586static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec)
587{
588 if (PageAnon(page) && PageSwapBacked(page) &&
589 !PageSwapCache(page) && !PageUnevictable(page)) {
590 int nr_pages = thp_nr_pages(page);
591
592 del_page_from_lru_list(page, lruvec);
593 ClearPageActive(page);
594 ClearPageReferenced(page);
595 /*
596 * Lazyfree pages are clean anonymous pages. They have
597 * PG_swapbacked flag cleared, to distinguish them from normal
598 * anonymous pages
599 */
600 ClearPageSwapBacked(page);
601 add_page_to_lru_list(page, lruvec);
602
603 __count_vm_events(PGLAZYFREE, nr_pages);
604 __count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE,
605 nr_pages);
606 }
607}
608
609/*
610 * Drain pages out of the cpu's pagevecs.
611 * Either "cpu" is the current CPU, and preemption has already been
612 * disabled; or "cpu" is being hot-unplugged, and is already dead.
613 */
614void lru_add_drain_cpu(int cpu)
615{
616 struct pagevec *pvec = &per_cpu(lru_pvecs.lru_add, cpu);
617
618 if (pagevec_count(pvec))
619 __pagevec_lru_add(pvec);
620
621 pvec = &per_cpu(lru_rotate.pvec, cpu);
622 /* Disabling interrupts below acts as a compiler barrier. */
623 if (data_race(pagevec_count(pvec))) {
624 unsigned long flags;
625
626 /* No harm done if a racing interrupt already did this */
627 local_lock_irqsave(&lru_rotate.lock, flags);
628 pagevec_lru_move_fn(pvec, pagevec_move_tail_fn);
629 local_unlock_irqrestore(&lru_rotate.lock, flags);
630 }
631
632 pvec = &per_cpu(lru_pvecs.lru_deactivate_file, cpu);
633 if (pagevec_count(pvec))
634 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn);
635
636 pvec = &per_cpu(lru_pvecs.lru_deactivate, cpu);
637 if (pagevec_count(pvec))
638 pagevec_lru_move_fn(pvec, lru_deactivate_fn);
639
640 pvec = &per_cpu(lru_pvecs.lru_lazyfree, cpu);
641 if (pagevec_count(pvec))
642 pagevec_lru_move_fn(pvec, lru_lazyfree_fn);
643
644 activate_page_drain(cpu);
645 invalidate_bh_lrus_cpu(cpu);
646}
647
648/**
649 * deactivate_file_page - forcefully deactivate a file page
650 * @page: page to deactivate
651 *
652 * This function hints the VM that @page is a good reclaim candidate,
653 * for example if its invalidation fails due to the page being dirty
654 * or under writeback.
655 */
656void deactivate_file_page(struct page *page)
657{
658 /*
659 * In a workload with many unevictable page such as mprotect,
660 * unevictable page deactivation for accelerating reclaim is pointless.
661 */
662 if (PageUnevictable(page))
663 return;
664
665 if (likely(get_page_unless_zero(page))) {
666 struct pagevec *pvec;
667
668 local_lock(&lru_pvecs.lock);
669 pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate_file);
670
671 if (pagevec_add_and_need_flush(pvec, page))
672 pagevec_lru_move_fn(pvec, lru_deactivate_file_fn);
673 local_unlock(&lru_pvecs.lock);
674 }
675}
676
677/*
678 * deactivate_page - deactivate a page
679 * @page: page to deactivate
680 *
681 * deactivate_page() moves @page to the inactive list if @page was on the active
682 * list and was not an unevictable page. This is done to accelerate the reclaim
683 * of @page.
684 */
685void deactivate_page(struct page *page)
686{
687 if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
688 struct pagevec *pvec;
689
690 local_lock(&lru_pvecs.lock);
691 pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate);
692 get_page(page);
693 if (pagevec_add_and_need_flush(pvec, page))
694 pagevec_lru_move_fn(pvec, lru_deactivate_fn);
695 local_unlock(&lru_pvecs.lock);
696 }
697}
698
699/**
700 * mark_page_lazyfree - make an anon page lazyfree
701 * @page: page to deactivate
702 *
703 * mark_page_lazyfree() moves @page to the inactive file list.
704 * This is done to accelerate the reclaim of @page.
705 */
706void mark_page_lazyfree(struct page *page)
707{
708 if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
709 !PageSwapCache(page) && !PageUnevictable(page)) {
710 struct pagevec *pvec;
711
712 local_lock(&lru_pvecs.lock);
713 pvec = this_cpu_ptr(&lru_pvecs.lru_lazyfree);
714 get_page(page);
715 if (pagevec_add_and_need_flush(pvec, page))
716 pagevec_lru_move_fn(pvec, lru_lazyfree_fn);
717 local_unlock(&lru_pvecs.lock);
718 }
719}
720
721void lru_add_drain(void)
722{
723 local_lock(&lru_pvecs.lock);
724 lru_add_drain_cpu(smp_processor_id());
725 local_unlock(&lru_pvecs.lock);
726}
727
728void lru_add_drain_cpu_zone(struct zone *zone)
729{
730 local_lock(&lru_pvecs.lock);
731 lru_add_drain_cpu(smp_processor_id());
732 drain_local_pages(zone);
733 local_unlock(&lru_pvecs.lock);
734}
735
736#ifdef CONFIG_SMP
737
738static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
739
740static void lru_add_drain_per_cpu(struct work_struct *dummy)
741{
742 lru_add_drain();
743}
744
745/*
746 * Doesn't need any cpu hotplug locking because we do rely on per-cpu
747 * kworkers being shut down before our page_alloc_cpu_dead callback is
748 * executed on the offlined cpu.
749 * Calling this function with cpu hotplug locks held can actually lead
750 * to obscure indirect dependencies via WQ context.
751 */
752inline void __lru_add_drain_all(bool force_all_cpus)
753{
754 /*
755 * lru_drain_gen - Global pages generation number
756 *
757 * (A) Definition: global lru_drain_gen = x implies that all generations
758 * 0 < n <= x are already *scheduled* for draining.
759 *
760 * This is an optimization for the highly-contended use case where a
761 * user space workload keeps constantly generating a flow of pages for
762 * each CPU.
763 */
764 static unsigned int lru_drain_gen;
765 static struct cpumask has_work;
766 static DEFINE_MUTEX(lock);
767 unsigned cpu, this_gen;
768
769 /*
770 * Make sure nobody triggers this path before mm_percpu_wq is fully
771 * initialized.
772 */
773 if (WARN_ON(!mm_percpu_wq))
774 return;
775
776 /*
777 * Guarantee pagevec counter stores visible by this CPU are visible to
778 * other CPUs before loading the current drain generation.
779 */
780 smp_mb();
781
782 /*
783 * (B) Locally cache global LRU draining generation number
784 *
785 * The read barrier ensures that the counter is loaded before the mutex
786 * is taken. It pairs with smp_mb() inside the mutex critical section
787 * at (D).
788 */
789 this_gen = smp_load_acquire(&lru_drain_gen);
790
791 mutex_lock(&lock);
792
793 /*
794 * (C) Exit the draining operation if a newer generation, from another
795 * lru_add_drain_all(), was already scheduled for draining. Check (A).
796 */
797 if (unlikely(this_gen != lru_drain_gen && !force_all_cpus))
798 goto done;
799
800 /*
801 * (D) Increment global generation number
802 *
803 * Pairs with smp_load_acquire() at (B), outside of the critical
804 * section. Use a full memory barrier to guarantee that the new global
805 * drain generation number is stored before loading pagevec counters.
806 *
807 * This pairing must be done here, before the for_each_online_cpu loop
808 * below which drains the page vectors.
809 *
810 * Let x, y, and z represent some system CPU numbers, where x < y < z.
811 * Assume CPU #z is in the middle of the for_each_online_cpu loop
812 * below and has already reached CPU #y's per-cpu data. CPU #x comes
813 * along, adds some pages to its per-cpu vectors, then calls
814 * lru_add_drain_all().
815 *
816 * If the paired barrier is done at any later step, e.g. after the
817 * loop, CPU #x will just exit at (C) and miss flushing out all of its
818 * added pages.
819 */
820 WRITE_ONCE(lru_drain_gen, lru_drain_gen + 1);
821 smp_mb();
822
823 cpumask_clear(&has_work);
824 for_each_online_cpu(cpu) {
825 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
826
827 if (force_all_cpus ||
828 pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||
829 data_race(pagevec_count(&per_cpu(lru_rotate.pvec, cpu))) ||
830 pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) ||
831 pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) ||
832 pagevec_count(&per_cpu(lru_pvecs.lru_lazyfree, cpu)) ||
833 need_activate_page_drain(cpu) ||
834 has_bh_in_lru(cpu, NULL)) {
835 INIT_WORK(work, lru_add_drain_per_cpu);
836 queue_work_on(cpu, mm_percpu_wq, work);
837 __cpumask_set_cpu(cpu, &has_work);
838 }
839 }
840
841 for_each_cpu(cpu, &has_work)
842 flush_work(&per_cpu(lru_add_drain_work, cpu));
843
844done:
845 mutex_unlock(&lock);
846}
847
848void lru_add_drain_all(void)
849{
850 __lru_add_drain_all(false);
851}
852#else
853void lru_add_drain_all(void)
854{
855 lru_add_drain();
856}
857#endif /* CONFIG_SMP */
858
859atomic_t lru_disable_count = ATOMIC_INIT(0);
860
861/*
862 * lru_cache_disable() needs to be called before we start compiling
863 * a list of pages to be migrated using isolate_lru_page().
864 * It drains pages on LRU cache and then disable on all cpus until
865 * lru_cache_enable is called.
866 *
867 * Must be paired with a call to lru_cache_enable().
868 */
869void lru_cache_disable(void)
870{
871 atomic_inc(&lru_disable_count);
872#ifdef CONFIG_SMP
873 /*
874 * lru_add_drain_all in the force mode will schedule draining on
875 * all online CPUs so any calls of lru_cache_disabled wrapped by
876 * local_lock or preemption disabled would be ordered by that.
877 * The atomic operation doesn't need to have stronger ordering
878 * requirements because that is enforeced by the scheduling
879 * guarantees.
880 */
881 __lru_add_drain_all(true);
882#else
883 lru_add_drain();
884#endif
885}
886
887/**
888 * release_pages - batched put_page()
889 * @pages: array of pages to release
890 * @nr: number of pages
891 *
892 * Decrement the reference count on all the pages in @pages. If it
893 * fell to zero, remove the page from the LRU and free it.
894 */
895void release_pages(struct page **pages, int nr)
896{
897 int i;
898 LIST_HEAD(pages_to_free);
899 struct lruvec *lruvec = NULL;
900 unsigned long flags;
901 unsigned int lock_batch;
902
903 for (i = 0; i < nr; i++) {
904 struct page *page = pages[i];
905
906 /*
907 * Make sure the IRQ-safe lock-holding time does not get
908 * excessive with a continuous string of pages from the
909 * same lruvec. The lock is held only if lruvec != NULL.
910 */
911 if (lruvec && ++lock_batch == SWAP_CLUSTER_MAX) {
912 unlock_page_lruvec_irqrestore(lruvec, flags);
913 lruvec = NULL;
914 }
915
916 page = compound_head(page);
917 if (is_huge_zero_page(page))
918 continue;
919
920 if (is_zone_device_page(page)) {
921 if (lruvec) {
922 unlock_page_lruvec_irqrestore(lruvec, flags);
923 lruvec = NULL;
924 }
925 /*
926 * ZONE_DEVICE pages that return 'false' from
927 * page_is_devmap_managed() do not require special
928 * processing, and instead, expect a call to
929 * put_page_testzero().
930 */
931 if (page_is_devmap_managed(page)) {
932 put_devmap_managed_page(page);
933 continue;
934 }
935 if (put_page_testzero(page))
936 put_dev_pagemap(page->pgmap);
937 continue;
938 }
939
940 if (!put_page_testzero(page))
941 continue;
942
943 if (PageCompound(page)) {
944 if (lruvec) {
945 unlock_page_lruvec_irqrestore(lruvec, flags);
946 lruvec = NULL;
947 }
948 __put_compound_page(page);
949 continue;
950 }
951
952 if (PageLRU(page)) {
953 struct lruvec *prev_lruvec = lruvec;
954
955 lruvec = relock_page_lruvec_irqsave(page, lruvec,
956 &flags);
957 if (prev_lruvec != lruvec)
958 lock_batch = 0;
959
960 del_page_from_lru_list(page, lruvec);
961 __clear_page_lru_flags(page);
962 }
963
964 __ClearPageWaiters(page);
965
966 list_add(&page->lru, &pages_to_free);
967 }
968 if (lruvec)
969 unlock_page_lruvec_irqrestore(lruvec, flags);
970
971 mem_cgroup_uncharge_list(&pages_to_free);
972 free_unref_page_list(&pages_to_free);
973}
974EXPORT_SYMBOL(release_pages);
975
976/*
977 * The pages which we're about to release may be in the deferred lru-addition
978 * queues. That would prevent them from really being freed right now. That's
979 * OK from a correctness point of view but is inefficient - those pages may be
980 * cache-warm and we want to give them back to the page allocator ASAP.
981 *
982 * So __pagevec_release() will drain those queues here. __pagevec_lru_add()
983 * and __pagevec_lru_add_active() call release_pages() directly to avoid
984 * mutual recursion.
985 */
986void __pagevec_release(struct pagevec *pvec)
987{
988 if (!pvec->percpu_pvec_drained) {
989 lru_add_drain();
990 pvec->percpu_pvec_drained = true;
991 }
992 release_pages(pvec->pages, pagevec_count(pvec));
993 pagevec_reinit(pvec);
994}
995EXPORT_SYMBOL(__pagevec_release);
996
997static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec)
998{
999 int was_unevictable = TestClearPageUnevictable(page);
1000 int nr_pages = thp_nr_pages(page);
1001
1002 VM_BUG_ON_PAGE(PageLRU(page), page);
1003
1004 /*
1005 * Page becomes evictable in two ways:
1006 * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()].
1007 * 2) Before acquiring LRU lock to put the page to correct LRU and then
1008 * a) do PageLRU check with lock [check_move_unevictable_pages]
1009 * b) do PageLRU check before lock [clear_page_mlock]
1010 *
1011 * (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need
1012 * following strict ordering:
1013 *
1014 * #0: __pagevec_lru_add_fn #1: clear_page_mlock
1015 *
1016 * SetPageLRU() TestClearPageMlocked()
1017 * smp_mb() // explicit ordering // above provides strict
1018 * // ordering
1019 * PageMlocked() PageLRU()
1020 *
1021 *
1022 * if '#1' does not observe setting of PG_lru by '#0' and fails
1023 * isolation, the explicit barrier will make sure that page_evictable
1024 * check will put the page in correct LRU. Without smp_mb(), SetPageLRU
1025 * can be reordered after PageMlocked check and can make '#1' to fail
1026 * the isolation of the page whose Mlocked bit is cleared (#0 is also
1027 * looking at the same page) and the evictable page will be stranded
1028 * in an unevictable LRU.
1029 */
1030 SetPageLRU(page);
1031 smp_mb__after_atomic();
1032
1033 if (page_evictable(page)) {
1034 if (was_unevictable)
1035 __count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages);
1036 } else {
1037 ClearPageActive(page);
1038 SetPageUnevictable(page);
1039 if (!was_unevictable)
1040 __count_vm_events(UNEVICTABLE_PGCULLED, nr_pages);
1041 }
1042
1043 add_page_to_lru_list(page, lruvec);
1044 trace_mm_lru_insertion(page);
1045}
1046
1047/*
1048 * Add the passed pages to the LRU, then drop the caller's refcount
1049 * on them. Reinitialises the caller's pagevec.
1050 */
1051void __pagevec_lru_add(struct pagevec *pvec)
1052{
1053 int i;
1054 struct lruvec *lruvec = NULL;
1055 unsigned long flags = 0;
1056
1057 for (i = 0; i < pagevec_count(pvec); i++) {
1058 struct page *page = pvec->pages[i];
1059
1060 lruvec = relock_page_lruvec_irqsave(page, lruvec, &flags);
1061 __pagevec_lru_add_fn(page, lruvec);
1062 }
1063 if (lruvec)
1064 unlock_page_lruvec_irqrestore(lruvec, flags);
1065 release_pages(pvec->pages, pvec->nr);
1066 pagevec_reinit(pvec);
1067}
1068
1069/**
1070 * pagevec_remove_exceptionals - pagevec exceptionals pruning
1071 * @pvec: The pagevec to prune
1072 *
1073 * find_get_entries() fills both pages and XArray value entries (aka
1074 * exceptional entries) into the pagevec. This function prunes all
1075 * exceptionals from @pvec without leaving holes, so that it can be
1076 * passed on to page-only pagevec operations.
1077 */
1078void pagevec_remove_exceptionals(struct pagevec *pvec)
1079{
1080 int i, j;
1081
1082 for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
1083 struct page *page = pvec->pages[i];
1084 if (!xa_is_value(page))
1085 pvec->pages[j++] = page;
1086 }
1087 pvec->nr = j;
1088}
1089
1090/**
1091 * pagevec_lookup_range - gang pagecache lookup
1092 * @pvec: Where the resulting pages are placed
1093 * @mapping: The address_space to search
1094 * @start: The starting page index
1095 * @end: The final page index
1096 *
1097 * pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE
1098 * pages in the mapping starting from index @start and upto index @end
1099 * (inclusive). The pages are placed in @pvec. pagevec_lookup() takes a
1100 * reference against the pages in @pvec.
1101 *
1102 * The search returns a group of mapping-contiguous pages with ascending
1103 * indexes. There may be holes in the indices due to not-present pages. We
1104 * also update @start to index the next page for the traversal.
1105 *
1106 * pagevec_lookup_range() returns the number of pages which were found. If this
1107 * number is smaller than PAGEVEC_SIZE, the end of specified range has been
1108 * reached.
1109 */
1110unsigned pagevec_lookup_range(struct pagevec *pvec,
1111 struct address_space *mapping, pgoff_t *start, pgoff_t end)
1112{
1113 pvec->nr = find_get_pages_range(mapping, start, end, PAGEVEC_SIZE,
1114 pvec->pages);
1115 return pagevec_count(pvec);
1116}
1117EXPORT_SYMBOL(pagevec_lookup_range);
1118
1119unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
1120 struct address_space *mapping, pgoff_t *index, pgoff_t end,
1121 xa_mark_t tag)
1122{
1123 pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
1124 PAGEVEC_SIZE, pvec->pages);
1125 return pagevec_count(pvec);
1126}
1127EXPORT_SYMBOL(pagevec_lookup_range_tag);
1128
1129/*
1130 * Perform any setup for the swap system
1131 */
1132void __init swap_setup(void)
1133{
1134 unsigned long megs = totalram_pages() >> (20 - PAGE_SHIFT);
1135
1136 /* Use a smaller cluster for small-memory machines */
1137 if (megs < 16)
1138 page_cluster = 2;
1139 else
1140 page_cluster = 3;
1141 /*
1142 * Right now other parts of the system means that we
1143 * _really_ don't want to cluster much more
1144 */
1145}
1146
1147#ifdef CONFIG_DEV_PAGEMAP_OPS
1148void put_devmap_managed_page(struct page *page)
1149{
1150 int count;
1151
1152 if (WARN_ON_ONCE(!page_is_devmap_managed(page)))
1153 return;
1154
1155 count = page_ref_dec_return(page);
1156
1157 /*
1158 * devmap page refcounts are 1-based, rather than 0-based: if
1159 * refcount is 1, then the page is free and the refcount is
1160 * stable because nobody holds a reference on the page.
1161 */
1162 if (count == 1)
1163 free_devmap_managed_page(page);
1164 else if (!count)
1165 __put_page(page);
1166}
1167EXPORT_SYMBOL(put_devmap_managed_page);
1168#endif