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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
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}
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? As a power of 2 */
47int page_cluster;
48const int page_cluster_max = 31;
49
50/* Protecting only lru_rotate.fbatch which requires disabling interrupts */
51struct lru_rotate {
52 local_lock_t lock;
53 struct folio_batch fbatch;
54};
55static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = {
56 .lock = INIT_LOCAL_LOCK(lock),
57};
58
59/*
60 * The following folio batches are grouped together because they are protected
61 * by disabling preemption (and interrupts remain enabled).
62 */
63struct cpu_fbatches {
64 local_lock_t lock;
65 struct folio_batch lru_add;
66 struct folio_batch lru_deactivate_file;
67 struct folio_batch lru_deactivate;
68 struct folio_batch lru_lazyfree;
69#ifdef CONFIG_SMP
70 struct folio_batch activate;
71#endif
72};
73static DEFINE_PER_CPU(struct cpu_fbatches, cpu_fbatches) = {
74 .lock = INIT_LOCAL_LOCK(lock),
75};
76
77static void __page_cache_release(struct folio *folio, struct lruvec **lruvecp,
78 unsigned long *flagsp)
79{
80 if (folio_test_lru(folio)) {
81 folio_lruvec_relock_irqsave(folio, lruvecp, flagsp);
82 lruvec_del_folio(*lruvecp, folio);
83 __folio_clear_lru_flags(folio);
84 }
85
86 /*
87 * In rare cases, when truncation or holepunching raced with
88 * munlock after VM_LOCKED was cleared, Mlocked may still be
89 * found set here. This does not indicate a problem, unless
90 * "unevictable_pgs_cleared" appears worryingly large.
91 */
92 if (unlikely(folio_test_mlocked(folio))) {
93 long nr_pages = folio_nr_pages(folio);
94
95 __folio_clear_mlocked(folio);
96 zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages);
97 count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages);
98 }
99}
100
101/*
102 * This path almost never happens for VM activity - pages are normally freed
103 * in batches. But it gets used by networking - and for compound pages.
104 */
105static void page_cache_release(struct folio *folio)
106{
107 struct lruvec *lruvec = NULL;
108 unsigned long flags;
109
110 __page_cache_release(folio, &lruvec, &flags);
111 if (lruvec)
112 unlock_page_lruvec_irqrestore(lruvec, flags);
113}
114
115static void __folio_put_small(struct folio *folio)
116{
117 page_cache_release(folio);
118 mem_cgroup_uncharge(folio);
119 free_unref_page(&folio->page, 0);
120}
121
122static void __folio_put_large(struct folio *folio)
123{
124 /*
125 * __page_cache_release() is supposed to be called for thp, not for
126 * hugetlb. This is because hugetlb page does never have PageLRU set
127 * (it's never listed to any LRU lists) and no memcg routines should
128 * be called for hugetlb (it has a separate hugetlb_cgroup.)
129 */
130 if (!folio_test_hugetlb(folio))
131 page_cache_release(folio);
132 destroy_large_folio(folio);
133}
134
135void __folio_put(struct folio *folio)
136{
137 if (unlikely(folio_is_zone_device(folio)))
138 free_zone_device_page(&folio->page);
139 else if (unlikely(folio_test_large(folio)))
140 __folio_put_large(folio);
141 else
142 __folio_put_small(folio);
143}
144EXPORT_SYMBOL(__folio_put);
145
146/**
147 * put_pages_list() - release a list of pages
148 * @pages: list of pages threaded on page->lru
149 *
150 * Release a list of pages which are strung together on page.lru.
151 */
152void put_pages_list(struct list_head *pages)
153{
154 struct folio_batch fbatch;
155 struct folio *folio, *next;
156
157 folio_batch_init(&fbatch);
158 list_for_each_entry_safe(folio, next, pages, lru) {
159 if (!folio_put_testzero(folio))
160 continue;
161 if (folio_test_large(folio)) {
162 __folio_put_large(folio);
163 continue;
164 }
165 /* LRU flag must be clear because it's passed using the lru */
166 if (folio_batch_add(&fbatch, folio) > 0)
167 continue;
168 free_unref_folios(&fbatch);
169 }
170
171 if (fbatch.nr)
172 free_unref_folios(&fbatch);
173 INIT_LIST_HEAD(pages);
174}
175EXPORT_SYMBOL(put_pages_list);
176
177typedef void (*move_fn_t)(struct lruvec *lruvec, struct folio *folio);
178
179static void lru_add_fn(struct lruvec *lruvec, struct folio *folio)
180{
181 int was_unevictable = folio_test_clear_unevictable(folio);
182 long nr_pages = folio_nr_pages(folio);
183
184 VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
185
186 /*
187 * Is an smp_mb__after_atomic() still required here, before
188 * folio_evictable() tests the mlocked flag, to rule out the possibility
189 * of stranding an evictable folio on an unevictable LRU? I think
190 * not, because __munlock_folio() only clears the mlocked flag
191 * while the LRU lock is held.
192 *
193 * (That is not true of __page_cache_release(), and not necessarily
194 * true of folios_put(): but those only clear the mlocked flag after
195 * folio_put_testzero() has excluded any other users of the folio.)
196 */
197 if (folio_evictable(folio)) {
198 if (was_unevictable)
199 __count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages);
200 } else {
201 folio_clear_active(folio);
202 folio_set_unevictable(folio);
203 /*
204 * folio->mlock_count = !!folio_test_mlocked(folio)?
205 * But that leaves __mlock_folio() in doubt whether another
206 * actor has already counted the mlock or not. Err on the
207 * safe side, underestimate, let page reclaim fix it, rather
208 * than leaving a page on the unevictable LRU indefinitely.
209 */
210 folio->mlock_count = 0;
211 if (!was_unevictable)
212 __count_vm_events(UNEVICTABLE_PGCULLED, nr_pages);
213 }
214
215 lruvec_add_folio(lruvec, folio);
216 trace_mm_lru_insertion(folio);
217}
218
219static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn)
220{
221 int i;
222 struct lruvec *lruvec = NULL;
223 unsigned long flags = 0;
224
225 for (i = 0; i < folio_batch_count(fbatch); i++) {
226 struct folio *folio = fbatch->folios[i];
227
228 /* block memcg migration while the folio moves between lru */
229 if (move_fn != lru_add_fn && !folio_test_clear_lru(folio))
230 continue;
231
232 folio_lruvec_relock_irqsave(folio, &lruvec, &flags);
233 move_fn(lruvec, folio);
234
235 folio_set_lru(folio);
236 }
237
238 if (lruvec)
239 unlock_page_lruvec_irqrestore(lruvec, flags);
240 folios_put(fbatch);
241}
242
243static void folio_batch_add_and_move(struct folio_batch *fbatch,
244 struct folio *folio, move_fn_t move_fn)
245{
246 if (folio_batch_add(fbatch, folio) && !folio_test_large(folio) &&
247 !lru_cache_disabled())
248 return;
249 folio_batch_move_lru(fbatch, move_fn);
250}
251
252static void lru_move_tail_fn(struct lruvec *lruvec, struct folio *folio)
253{
254 if (!folio_test_unevictable(folio)) {
255 lruvec_del_folio(lruvec, folio);
256 folio_clear_active(folio);
257 lruvec_add_folio_tail(lruvec, folio);
258 __count_vm_events(PGROTATED, folio_nr_pages(folio));
259 }
260}
261
262/*
263 * Writeback is about to end against a folio which has been marked for
264 * immediate reclaim. If it still appears to be reclaimable, move it
265 * to the tail of the inactive list.
266 *
267 * folio_rotate_reclaimable() must disable IRQs, to prevent nasty races.
268 */
269void folio_rotate_reclaimable(struct folio *folio)
270{
271 if (!folio_test_locked(folio) && !folio_test_dirty(folio) &&
272 !folio_test_unevictable(folio) && folio_test_lru(folio)) {
273 struct folio_batch *fbatch;
274 unsigned long flags;
275
276 folio_get(folio);
277 local_lock_irqsave(&lru_rotate.lock, flags);
278 fbatch = this_cpu_ptr(&lru_rotate.fbatch);
279 folio_batch_add_and_move(fbatch, folio, lru_move_tail_fn);
280 local_unlock_irqrestore(&lru_rotate.lock, flags);
281 }
282}
283
284void lru_note_cost(struct lruvec *lruvec, bool file,
285 unsigned int nr_io, unsigned int nr_rotated)
286{
287 unsigned long cost;
288
289 /*
290 * Reflect the relative cost of incurring IO and spending CPU
291 * time on rotations. This doesn't attempt to make a precise
292 * comparison, it just says: if reloads are about comparable
293 * between the LRU lists, or rotations are overwhelmingly
294 * different between them, adjust scan balance for CPU work.
295 */
296 cost = nr_io * SWAP_CLUSTER_MAX + nr_rotated;
297
298 do {
299 unsigned long lrusize;
300
301 /*
302 * Hold lruvec->lru_lock is safe here, since
303 * 1) The pinned lruvec in reclaim, or
304 * 2) From a pre-LRU page during refault (which also holds the
305 * rcu lock, so would be safe even if the page was on the LRU
306 * and could move simultaneously to a new lruvec).
307 */
308 spin_lock_irq(&lruvec->lru_lock);
309 /* Record cost event */
310 if (file)
311 lruvec->file_cost += cost;
312 else
313 lruvec->anon_cost += cost;
314
315 /*
316 * Decay previous events
317 *
318 * Because workloads change over time (and to avoid
319 * overflow) we keep these statistics as a floating
320 * average, which ends up weighing recent refaults
321 * more than old ones.
322 */
323 lrusize = lruvec_page_state(lruvec, NR_INACTIVE_ANON) +
324 lruvec_page_state(lruvec, NR_ACTIVE_ANON) +
325 lruvec_page_state(lruvec, NR_INACTIVE_FILE) +
326 lruvec_page_state(lruvec, NR_ACTIVE_FILE);
327
328 if (lruvec->file_cost + lruvec->anon_cost > lrusize / 4) {
329 lruvec->file_cost /= 2;
330 lruvec->anon_cost /= 2;
331 }
332 spin_unlock_irq(&lruvec->lru_lock);
333 } while ((lruvec = parent_lruvec(lruvec)));
334}
335
336void lru_note_cost_refault(struct folio *folio)
337{
338 lru_note_cost(folio_lruvec(folio), folio_is_file_lru(folio),
339 folio_nr_pages(folio), 0);
340}
341
342static void folio_activate_fn(struct lruvec *lruvec, struct folio *folio)
343{
344 if (!folio_test_active(folio) && !folio_test_unevictable(folio)) {
345 long nr_pages = folio_nr_pages(folio);
346
347 lruvec_del_folio(lruvec, folio);
348 folio_set_active(folio);
349 lruvec_add_folio(lruvec, folio);
350 trace_mm_lru_activate(folio);
351
352 __count_vm_events(PGACTIVATE, nr_pages);
353 __count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE,
354 nr_pages);
355 }
356}
357
358#ifdef CONFIG_SMP
359static void folio_activate_drain(int cpu)
360{
361 struct folio_batch *fbatch = &per_cpu(cpu_fbatches.activate, cpu);
362
363 if (folio_batch_count(fbatch))
364 folio_batch_move_lru(fbatch, folio_activate_fn);
365}
366
367void folio_activate(struct folio *folio)
368{
369 if (folio_test_lru(folio) && !folio_test_active(folio) &&
370 !folio_test_unevictable(folio)) {
371 struct folio_batch *fbatch;
372
373 folio_get(folio);
374 local_lock(&cpu_fbatches.lock);
375 fbatch = this_cpu_ptr(&cpu_fbatches.activate);
376 folio_batch_add_and_move(fbatch, folio, folio_activate_fn);
377 local_unlock(&cpu_fbatches.lock);
378 }
379}
380
381#else
382static inline void folio_activate_drain(int cpu)
383{
384}
385
386void folio_activate(struct folio *folio)
387{
388 struct lruvec *lruvec;
389
390 if (folio_test_clear_lru(folio)) {
391 lruvec = folio_lruvec_lock_irq(folio);
392 folio_activate_fn(lruvec, folio);
393 unlock_page_lruvec_irq(lruvec);
394 folio_set_lru(folio);
395 }
396}
397#endif
398
399static void __lru_cache_activate_folio(struct folio *folio)
400{
401 struct folio_batch *fbatch;
402 int i;
403
404 local_lock(&cpu_fbatches.lock);
405 fbatch = this_cpu_ptr(&cpu_fbatches.lru_add);
406
407 /*
408 * Search backwards on the optimistic assumption that the folio being
409 * activated has just been added to this batch. Note that only
410 * the local batch is examined as a !LRU folio could be in the
411 * process of being released, reclaimed, migrated or on a remote
412 * batch that is currently being drained. Furthermore, marking
413 * a remote batch's folio active potentially hits a race where
414 * a folio is marked active just after it is added to the inactive
415 * list causing accounting errors and BUG_ON checks to trigger.
416 */
417 for (i = folio_batch_count(fbatch) - 1; i >= 0; i--) {
418 struct folio *batch_folio = fbatch->folios[i];
419
420 if (batch_folio == folio) {
421 folio_set_active(folio);
422 break;
423 }
424 }
425
426 local_unlock(&cpu_fbatches.lock);
427}
428
429#ifdef CONFIG_LRU_GEN
430static void folio_inc_refs(struct folio *folio)
431{
432 unsigned long new_flags, old_flags = READ_ONCE(folio->flags);
433
434 if (folio_test_unevictable(folio))
435 return;
436
437 if (!folio_test_referenced(folio)) {
438 folio_set_referenced(folio);
439 return;
440 }
441
442 if (!folio_test_workingset(folio)) {
443 folio_set_workingset(folio);
444 return;
445 }
446
447 /* see the comment on MAX_NR_TIERS */
448 do {
449 new_flags = old_flags & LRU_REFS_MASK;
450 if (new_flags == LRU_REFS_MASK)
451 break;
452
453 new_flags += BIT(LRU_REFS_PGOFF);
454 new_flags |= old_flags & ~LRU_REFS_MASK;
455 } while (!try_cmpxchg(&folio->flags, &old_flags, new_flags));
456}
457#else
458static void folio_inc_refs(struct folio *folio)
459{
460}
461#endif /* CONFIG_LRU_GEN */
462
463/*
464 * Mark a page as having seen activity.
465 *
466 * inactive,unreferenced -> inactive,referenced
467 * inactive,referenced -> active,unreferenced
468 * active,unreferenced -> active,referenced
469 *
470 * When a newly allocated page is not yet visible, so safe for non-atomic ops,
471 * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
472 */
473void folio_mark_accessed(struct folio *folio)
474{
475 if (lru_gen_enabled()) {
476 folio_inc_refs(folio);
477 return;
478 }
479
480 if (!folio_test_referenced(folio)) {
481 folio_set_referenced(folio);
482 } else if (folio_test_unevictable(folio)) {
483 /*
484 * Unevictable pages are on the "LRU_UNEVICTABLE" list. But,
485 * this list is never rotated or maintained, so marking an
486 * unevictable page accessed has no effect.
487 */
488 } else if (!folio_test_active(folio)) {
489 /*
490 * If the folio is on the LRU, queue it for activation via
491 * cpu_fbatches.activate. Otherwise, assume the folio is in a
492 * folio_batch, mark it active and it'll be moved to the active
493 * LRU on the next drain.
494 */
495 if (folio_test_lru(folio))
496 folio_activate(folio);
497 else
498 __lru_cache_activate_folio(folio);
499 folio_clear_referenced(folio);
500 workingset_activation(folio);
501 }
502 if (folio_test_idle(folio))
503 folio_clear_idle(folio);
504}
505EXPORT_SYMBOL(folio_mark_accessed);
506
507/**
508 * folio_add_lru - Add a folio to an LRU list.
509 * @folio: The folio to be added to the LRU.
510 *
511 * Queue the folio for addition to the LRU. The decision on whether
512 * to add the page to the [in]active [file|anon] list is deferred until the
513 * folio_batch is drained. This gives a chance for the caller of folio_add_lru()
514 * have the folio added to the active list using folio_mark_accessed().
515 */
516void folio_add_lru(struct folio *folio)
517{
518 struct folio_batch *fbatch;
519
520 VM_BUG_ON_FOLIO(folio_test_active(folio) &&
521 folio_test_unevictable(folio), folio);
522 VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
523
524 /* see the comment in lru_gen_add_folio() */
525 if (lru_gen_enabled() && !folio_test_unevictable(folio) &&
526 lru_gen_in_fault() && !(current->flags & PF_MEMALLOC))
527 folio_set_active(folio);
528
529 folio_get(folio);
530 local_lock(&cpu_fbatches.lock);
531 fbatch = this_cpu_ptr(&cpu_fbatches.lru_add);
532 folio_batch_add_and_move(fbatch, folio, lru_add_fn);
533 local_unlock(&cpu_fbatches.lock);
534}
535EXPORT_SYMBOL(folio_add_lru);
536
537/**
538 * folio_add_lru_vma() - Add a folio to the appropate LRU list for this VMA.
539 * @folio: The folio to be added to the LRU.
540 * @vma: VMA in which the folio is mapped.
541 *
542 * If the VMA is mlocked, @folio is added to the unevictable list.
543 * Otherwise, it is treated the same way as folio_add_lru().
544 */
545void folio_add_lru_vma(struct folio *folio, struct vm_area_struct *vma)
546{
547 VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
548
549 if (unlikely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED))
550 mlock_new_folio(folio);
551 else
552 folio_add_lru(folio);
553}
554
555/*
556 * If the folio cannot be invalidated, it is moved to the
557 * inactive list to speed up its reclaim. It is moved to the
558 * head of the list, rather than the tail, to give the flusher
559 * threads some time to write it out, as this is much more
560 * effective than the single-page writeout from reclaim.
561 *
562 * If the folio isn't mapped and dirty/writeback, the folio
563 * could be reclaimed asap using the reclaim flag.
564 *
565 * 1. active, mapped folio -> none
566 * 2. active, dirty/writeback folio -> inactive, head, reclaim
567 * 3. inactive, mapped folio -> none
568 * 4. inactive, dirty/writeback folio -> inactive, head, reclaim
569 * 5. inactive, clean -> inactive, tail
570 * 6. Others -> none
571 *
572 * In 4, it moves to the head of the inactive list so the folio is
573 * written out by flusher threads as this is much more efficient
574 * than the single-page writeout from reclaim.
575 */
576static void lru_deactivate_file_fn(struct lruvec *lruvec, struct folio *folio)
577{
578 bool active = folio_test_active(folio);
579 long nr_pages = folio_nr_pages(folio);
580
581 if (folio_test_unevictable(folio))
582 return;
583
584 /* Some processes are using the folio */
585 if (folio_mapped(folio))
586 return;
587
588 lruvec_del_folio(lruvec, folio);
589 folio_clear_active(folio);
590 folio_clear_referenced(folio);
591
592 if (folio_test_writeback(folio) || folio_test_dirty(folio)) {
593 /*
594 * Setting the reclaim flag could race with
595 * folio_end_writeback() and confuse readahead. But the
596 * race window is _really_ small and it's not a critical
597 * problem.
598 */
599 lruvec_add_folio(lruvec, folio);
600 folio_set_reclaim(folio);
601 } else {
602 /*
603 * The folio's writeback ended while it was in the batch.
604 * We move that folio to the tail of the inactive list.
605 */
606 lruvec_add_folio_tail(lruvec, folio);
607 __count_vm_events(PGROTATED, nr_pages);
608 }
609
610 if (active) {
611 __count_vm_events(PGDEACTIVATE, nr_pages);
612 __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
613 nr_pages);
614 }
615}
616
617static void lru_deactivate_fn(struct lruvec *lruvec, struct folio *folio)
618{
619 if (!folio_test_unevictable(folio) && (folio_test_active(folio) || lru_gen_enabled())) {
620 long nr_pages = folio_nr_pages(folio);
621
622 lruvec_del_folio(lruvec, folio);
623 folio_clear_active(folio);
624 folio_clear_referenced(folio);
625 lruvec_add_folio(lruvec, folio);
626
627 __count_vm_events(PGDEACTIVATE, nr_pages);
628 __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
629 nr_pages);
630 }
631}
632
633static void lru_lazyfree_fn(struct lruvec *lruvec, struct folio *folio)
634{
635 if (folio_test_anon(folio) && folio_test_swapbacked(folio) &&
636 !folio_test_swapcache(folio) && !folio_test_unevictable(folio)) {
637 long nr_pages = folio_nr_pages(folio);
638
639 lruvec_del_folio(lruvec, folio);
640 folio_clear_active(folio);
641 folio_clear_referenced(folio);
642 /*
643 * Lazyfree folios are clean anonymous folios. They have
644 * the swapbacked flag cleared, to distinguish them from normal
645 * anonymous folios
646 */
647 folio_clear_swapbacked(folio);
648 lruvec_add_folio(lruvec, folio);
649
650 __count_vm_events(PGLAZYFREE, nr_pages);
651 __count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE,
652 nr_pages);
653 }
654}
655
656/*
657 * Drain pages out of the cpu's folio_batch.
658 * Either "cpu" is the current CPU, and preemption has already been
659 * disabled; or "cpu" is being hot-unplugged, and is already dead.
660 */
661void lru_add_drain_cpu(int cpu)
662{
663 struct cpu_fbatches *fbatches = &per_cpu(cpu_fbatches, cpu);
664 struct folio_batch *fbatch = &fbatches->lru_add;
665
666 if (folio_batch_count(fbatch))
667 folio_batch_move_lru(fbatch, lru_add_fn);
668
669 fbatch = &per_cpu(lru_rotate.fbatch, cpu);
670 /* Disabling interrupts below acts as a compiler barrier. */
671 if (data_race(folio_batch_count(fbatch))) {
672 unsigned long flags;
673
674 /* No harm done if a racing interrupt already did this */
675 local_lock_irqsave(&lru_rotate.lock, flags);
676 folio_batch_move_lru(fbatch, lru_move_tail_fn);
677 local_unlock_irqrestore(&lru_rotate.lock, flags);
678 }
679
680 fbatch = &fbatches->lru_deactivate_file;
681 if (folio_batch_count(fbatch))
682 folio_batch_move_lru(fbatch, lru_deactivate_file_fn);
683
684 fbatch = &fbatches->lru_deactivate;
685 if (folio_batch_count(fbatch))
686 folio_batch_move_lru(fbatch, lru_deactivate_fn);
687
688 fbatch = &fbatches->lru_lazyfree;
689 if (folio_batch_count(fbatch))
690 folio_batch_move_lru(fbatch, lru_lazyfree_fn);
691
692 folio_activate_drain(cpu);
693}
694
695/**
696 * deactivate_file_folio() - Deactivate a file folio.
697 * @folio: Folio to deactivate.
698 *
699 * This function hints to the VM that @folio is a good reclaim candidate,
700 * for example if its invalidation fails due to the folio being dirty
701 * or under writeback.
702 *
703 * Context: Caller holds a reference on the folio.
704 */
705void deactivate_file_folio(struct folio *folio)
706{
707 struct folio_batch *fbatch;
708
709 /* Deactivating an unevictable folio will not accelerate reclaim */
710 if (folio_test_unevictable(folio))
711 return;
712
713 folio_get(folio);
714 local_lock(&cpu_fbatches.lock);
715 fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate_file);
716 folio_batch_add_and_move(fbatch, folio, lru_deactivate_file_fn);
717 local_unlock(&cpu_fbatches.lock);
718}
719
720/*
721 * folio_deactivate - deactivate a folio
722 * @folio: folio to deactivate
723 *
724 * folio_deactivate() moves @folio to the inactive list if @folio was on the
725 * active list and was not unevictable. This is done to accelerate the
726 * reclaim of @folio.
727 */
728void folio_deactivate(struct folio *folio)
729{
730 if (folio_test_lru(folio) && !folio_test_unevictable(folio) &&
731 (folio_test_active(folio) || lru_gen_enabled())) {
732 struct folio_batch *fbatch;
733
734 folio_get(folio);
735 local_lock(&cpu_fbatches.lock);
736 fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate);
737 folio_batch_add_and_move(fbatch, folio, lru_deactivate_fn);
738 local_unlock(&cpu_fbatches.lock);
739 }
740}
741
742/**
743 * folio_mark_lazyfree - make an anon folio lazyfree
744 * @folio: folio to deactivate
745 *
746 * folio_mark_lazyfree() moves @folio to the inactive file list.
747 * This is done to accelerate the reclaim of @folio.
748 */
749void folio_mark_lazyfree(struct folio *folio)
750{
751 if (folio_test_lru(folio) && folio_test_anon(folio) &&
752 folio_test_swapbacked(folio) && !folio_test_swapcache(folio) &&
753 !folio_test_unevictable(folio)) {
754 struct folio_batch *fbatch;
755
756 folio_get(folio);
757 local_lock(&cpu_fbatches.lock);
758 fbatch = this_cpu_ptr(&cpu_fbatches.lru_lazyfree);
759 folio_batch_add_and_move(fbatch, folio, lru_lazyfree_fn);
760 local_unlock(&cpu_fbatches.lock);
761 }
762}
763
764void lru_add_drain(void)
765{
766 local_lock(&cpu_fbatches.lock);
767 lru_add_drain_cpu(smp_processor_id());
768 local_unlock(&cpu_fbatches.lock);
769 mlock_drain_local();
770}
771
772/*
773 * It's called from per-cpu workqueue context in SMP case so
774 * lru_add_drain_cpu and invalidate_bh_lrus_cpu should run on
775 * the same cpu. It shouldn't be a problem in !SMP case since
776 * the core is only one and the locks will disable preemption.
777 */
778static void lru_add_and_bh_lrus_drain(void)
779{
780 local_lock(&cpu_fbatches.lock);
781 lru_add_drain_cpu(smp_processor_id());
782 local_unlock(&cpu_fbatches.lock);
783 invalidate_bh_lrus_cpu();
784 mlock_drain_local();
785}
786
787void lru_add_drain_cpu_zone(struct zone *zone)
788{
789 local_lock(&cpu_fbatches.lock);
790 lru_add_drain_cpu(smp_processor_id());
791 drain_local_pages(zone);
792 local_unlock(&cpu_fbatches.lock);
793 mlock_drain_local();
794}
795
796#ifdef CONFIG_SMP
797
798static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
799
800static void lru_add_drain_per_cpu(struct work_struct *dummy)
801{
802 lru_add_and_bh_lrus_drain();
803}
804
805static bool cpu_needs_drain(unsigned int cpu)
806{
807 struct cpu_fbatches *fbatches = &per_cpu(cpu_fbatches, cpu);
808
809 /* Check these in order of likelihood that they're not zero */
810 return folio_batch_count(&fbatches->lru_add) ||
811 data_race(folio_batch_count(&per_cpu(lru_rotate.fbatch, cpu))) ||
812 folio_batch_count(&fbatches->lru_deactivate_file) ||
813 folio_batch_count(&fbatches->lru_deactivate) ||
814 folio_batch_count(&fbatches->lru_lazyfree) ||
815 folio_batch_count(&fbatches->activate) ||
816 need_mlock_drain(cpu) ||
817 has_bh_in_lru(cpu, NULL);
818}
819
820/*
821 * Doesn't need any cpu hotplug locking because we do rely on per-cpu
822 * kworkers being shut down before our page_alloc_cpu_dead callback is
823 * executed on the offlined cpu.
824 * Calling this function with cpu hotplug locks held can actually lead
825 * to obscure indirect dependencies via WQ context.
826 */
827static inline void __lru_add_drain_all(bool force_all_cpus)
828{
829 /*
830 * lru_drain_gen - Global pages generation number
831 *
832 * (A) Definition: global lru_drain_gen = x implies that all generations
833 * 0 < n <= x are already *scheduled* for draining.
834 *
835 * This is an optimization for the highly-contended use case where a
836 * user space workload keeps constantly generating a flow of pages for
837 * each CPU.
838 */
839 static unsigned int lru_drain_gen;
840 static struct cpumask has_work;
841 static DEFINE_MUTEX(lock);
842 unsigned cpu, this_gen;
843
844 /*
845 * Make sure nobody triggers this path before mm_percpu_wq is fully
846 * initialized.
847 */
848 if (WARN_ON(!mm_percpu_wq))
849 return;
850
851 /*
852 * Guarantee folio_batch counter stores visible by this CPU
853 * are visible to other CPUs before loading the current drain
854 * generation.
855 */
856 smp_mb();
857
858 /*
859 * (B) Locally cache global LRU draining generation number
860 *
861 * The read barrier ensures that the counter is loaded before the mutex
862 * is taken. It pairs with smp_mb() inside the mutex critical section
863 * at (D).
864 */
865 this_gen = smp_load_acquire(&lru_drain_gen);
866
867 mutex_lock(&lock);
868
869 /*
870 * (C) Exit the draining operation if a newer generation, from another
871 * lru_add_drain_all(), was already scheduled for draining. Check (A).
872 */
873 if (unlikely(this_gen != lru_drain_gen && !force_all_cpus))
874 goto done;
875
876 /*
877 * (D) Increment global generation number
878 *
879 * Pairs with smp_load_acquire() at (B), outside of the critical
880 * section. Use a full memory barrier to guarantee that the
881 * new global drain generation number is stored before loading
882 * folio_batch counters.
883 *
884 * This pairing must be done here, before the for_each_online_cpu loop
885 * below which drains the page vectors.
886 *
887 * Let x, y, and z represent some system CPU numbers, where x < y < z.
888 * Assume CPU #z is in the middle of the for_each_online_cpu loop
889 * below and has already reached CPU #y's per-cpu data. CPU #x comes
890 * along, adds some pages to its per-cpu vectors, then calls
891 * lru_add_drain_all().
892 *
893 * If the paired barrier is done at any later step, e.g. after the
894 * loop, CPU #x will just exit at (C) and miss flushing out all of its
895 * added pages.
896 */
897 WRITE_ONCE(lru_drain_gen, lru_drain_gen + 1);
898 smp_mb();
899
900 cpumask_clear(&has_work);
901 for_each_online_cpu(cpu) {
902 struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
903
904 if (cpu_needs_drain(cpu)) {
905 INIT_WORK(work, lru_add_drain_per_cpu);
906 queue_work_on(cpu, mm_percpu_wq, work);
907 __cpumask_set_cpu(cpu, &has_work);
908 }
909 }
910
911 for_each_cpu(cpu, &has_work)
912 flush_work(&per_cpu(lru_add_drain_work, cpu));
913
914done:
915 mutex_unlock(&lock);
916}
917
918void lru_add_drain_all(void)
919{
920 __lru_add_drain_all(false);
921}
922#else
923void lru_add_drain_all(void)
924{
925 lru_add_drain();
926}
927#endif /* CONFIG_SMP */
928
929atomic_t lru_disable_count = ATOMIC_INIT(0);
930
931/*
932 * lru_cache_disable() needs to be called before we start compiling
933 * a list of pages to be migrated using isolate_lru_page().
934 * It drains pages on LRU cache and then disable on all cpus until
935 * lru_cache_enable is called.
936 *
937 * Must be paired with a call to lru_cache_enable().
938 */
939void lru_cache_disable(void)
940{
941 atomic_inc(&lru_disable_count);
942 /*
943 * Readers of lru_disable_count are protected by either disabling
944 * preemption or rcu_read_lock:
945 *
946 * preempt_disable, local_irq_disable [bh_lru_lock()]
947 * rcu_read_lock [rt_spin_lock CONFIG_PREEMPT_RT]
948 * preempt_disable [local_lock !CONFIG_PREEMPT_RT]
949 *
950 * Since v5.1 kernel, synchronize_rcu() is guaranteed to wait on
951 * preempt_disable() regions of code. So any CPU which sees
952 * lru_disable_count = 0 will have exited the critical
953 * section when synchronize_rcu() returns.
954 */
955 synchronize_rcu_expedited();
956#ifdef CONFIG_SMP
957 __lru_add_drain_all(true);
958#else
959 lru_add_and_bh_lrus_drain();
960#endif
961}
962
963/**
964 * folios_put_refs - Reduce the reference count on a batch of folios.
965 * @folios: The folios.
966 * @refs: The number of refs to subtract from each folio.
967 *
968 * Like folio_put(), but for a batch of folios. This is more efficient
969 * than writing the loop yourself as it will optimise the locks which need
970 * to be taken if the folios are freed. The folios batch is returned
971 * empty and ready to be reused for another batch; there is no need
972 * to reinitialise it. If @refs is NULL, we subtract one from each
973 * folio refcount.
974 *
975 * Context: May be called in process or interrupt context, but not in NMI
976 * context. May be called while holding a spinlock.
977 */
978void folios_put_refs(struct folio_batch *folios, unsigned int *refs)
979{
980 int i, j;
981 struct lruvec *lruvec = NULL;
982 unsigned long flags = 0;
983
984 for (i = 0, j = 0; i < folios->nr; i++) {
985 struct folio *folio = folios->folios[i];
986 unsigned int nr_refs = refs ? refs[i] : 1;
987
988 if (is_huge_zero_page(&folio->page))
989 continue;
990
991 if (folio_is_zone_device(folio)) {
992 if (lruvec) {
993 unlock_page_lruvec_irqrestore(lruvec, flags);
994 lruvec = NULL;
995 }
996 if (put_devmap_managed_page_refs(&folio->page, nr_refs))
997 continue;
998 if (folio_ref_sub_and_test(folio, nr_refs))
999 free_zone_device_page(&folio->page);
1000 continue;
1001 }
1002
1003 if (!folio_ref_sub_and_test(folio, nr_refs))
1004 continue;
1005
1006 /* hugetlb has its own memcg */
1007 if (folio_test_hugetlb(folio)) {
1008 if (lruvec) {
1009 unlock_page_lruvec_irqrestore(lruvec, flags);
1010 lruvec = NULL;
1011 }
1012 free_huge_folio(folio);
1013 continue;
1014 }
1015 if (folio_test_large(folio) &&
1016 folio_test_large_rmappable(folio))
1017 folio_undo_large_rmappable(folio);
1018
1019 __page_cache_release(folio, &lruvec, &flags);
1020
1021 if (j != i)
1022 folios->folios[j] = folio;
1023 j++;
1024 }
1025 if (lruvec)
1026 unlock_page_lruvec_irqrestore(lruvec, flags);
1027 if (!j) {
1028 folio_batch_reinit(folios);
1029 return;
1030 }
1031
1032 folios->nr = j;
1033 mem_cgroup_uncharge_folios(folios);
1034 free_unref_folios(folios);
1035}
1036EXPORT_SYMBOL(folios_put_refs);
1037
1038/**
1039 * release_pages - batched put_page()
1040 * @arg: array of pages to release
1041 * @nr: number of pages
1042 *
1043 * Decrement the reference count on all the pages in @arg. If it
1044 * fell to zero, remove the page from the LRU and free it.
1045 *
1046 * Note that the argument can be an array of pages, encoded pages,
1047 * or folio pointers. We ignore any encoded bits, and turn any of
1048 * them into just a folio that gets free'd.
1049 */
1050void release_pages(release_pages_arg arg, int nr)
1051{
1052 struct folio_batch fbatch;
1053 int refs[PAGEVEC_SIZE];
1054 struct encoded_page **encoded = arg.encoded_pages;
1055 int i;
1056
1057 folio_batch_init(&fbatch);
1058 for (i = 0; i < nr; i++) {
1059 /* Turn any of the argument types into a folio */
1060 struct folio *folio = page_folio(encoded_page_ptr(encoded[i]));
1061
1062 /* Is our next entry actually "nr_pages" -> "nr_refs" ? */
1063 refs[fbatch.nr] = 1;
1064 if (unlikely(encoded_page_flags(encoded[i]) &
1065 ENCODED_PAGE_BIT_NR_PAGES_NEXT))
1066 refs[fbatch.nr] = encoded_nr_pages(encoded[++i]);
1067
1068 if (folio_batch_add(&fbatch, folio) > 0)
1069 continue;
1070 folios_put_refs(&fbatch, refs);
1071 }
1072
1073 if (fbatch.nr)
1074 folios_put_refs(&fbatch, refs);
1075}
1076EXPORT_SYMBOL(release_pages);
1077
1078/*
1079 * The folios which we're about to release may be in the deferred lru-addition
1080 * queues. That would prevent them from really being freed right now. That's
1081 * OK from a correctness point of view but is inefficient - those folios may be
1082 * cache-warm and we want to give them back to the page allocator ASAP.
1083 *
1084 * So __folio_batch_release() will drain those queues here.
1085 * folio_batch_move_lru() calls folios_put() directly to avoid
1086 * mutual recursion.
1087 */
1088void __folio_batch_release(struct folio_batch *fbatch)
1089{
1090 if (!fbatch->percpu_pvec_drained) {
1091 lru_add_drain();
1092 fbatch->percpu_pvec_drained = true;
1093 }
1094 folios_put(fbatch);
1095}
1096EXPORT_SYMBOL(__folio_batch_release);
1097
1098/**
1099 * folio_batch_remove_exceptionals() - Prune non-folios from a batch.
1100 * @fbatch: The batch to prune
1101 *
1102 * find_get_entries() fills a batch with both folios and shadow/swap/DAX
1103 * entries. This function prunes all the non-folio entries from @fbatch
1104 * without leaving holes, so that it can be passed on to folio-only batch
1105 * operations.
1106 */
1107void folio_batch_remove_exceptionals(struct folio_batch *fbatch)
1108{
1109 unsigned int i, j;
1110
1111 for (i = 0, j = 0; i < folio_batch_count(fbatch); i++) {
1112 struct folio *folio = fbatch->folios[i];
1113 if (!xa_is_value(folio))
1114 fbatch->folios[j++] = folio;
1115 }
1116 fbatch->nr = j;
1117}
1118
1119/*
1120 * Perform any setup for the swap system
1121 */
1122void __init swap_setup(void)
1123{
1124 unsigned long megs = totalram_pages() >> (20 - PAGE_SHIFT);
1125
1126 /* Use a smaller cluster for small-memory machines */
1127 if (megs < 16)
1128 page_cluster = 2;
1129 else
1130 page_cluster = 3;
1131 /*
1132 * Right now other parts of the system means that we
1133 * _really_ don't want to cluster much more
1134 */
1135}