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133d2743ef
If no pages were pinned, 0 is returned in fact. Fix the corresponding comment. [akpm@linux-foundation.org: s/nr_pages/nr_segs/ also, per David, reflow comment] Link: https://lkml.kernel.org/r/20220509131416.17553-15-linmiaohe@huawei.com Signed-off-by: Miaohe Lin <linmiaohe@huawei.com> Reviewed-by: David Hildenbrand <david@redhat.com> Cc: Alistair Popple <apopple@nvidia.com> Cc: David Howells <dhowells@redhat.com> Cc: Matthew Wilcox <willy@infradead.org> Cc: Naoya Horiguchi <naoya.horiguchi@nec.com> Cc: NeilBrown <neilb@suse.de> Cc: Peter Xu <peterx@redhat.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Vlastimil Babka <vbabka@suse.cz> Cc: Oscar Salvador <osalvador@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
1145 lines
32 KiB
C
1145 lines
32 KiB
C
// SPDX-License-Identifier: GPL-2.0-only
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/*
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* linux/mm/swap.c
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*
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* Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
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*/
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/*
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* This file contains the default values for the operation of the
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* Linux VM subsystem. Fine-tuning documentation can be found in
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* Documentation/admin-guide/sysctl/vm.rst.
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* Started 18.12.91
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* Swap aging added 23.2.95, Stephen Tweedie.
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* Buffermem limits added 12.3.98, Rik van Riel.
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*/
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#include <linux/mm.h>
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#include <linux/sched.h>
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#include <linux/kernel_stat.h>
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#include <linux/swap.h>
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#include <linux/mman.h>
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#include <linux/pagemap.h>
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#include <linux/pagevec.h>
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#include <linux/init.h>
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#include <linux/export.h>
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#include <linux/mm_inline.h>
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#include <linux/percpu_counter.h>
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#include <linux/memremap.h>
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#include <linux/percpu.h>
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#include <linux/cpu.h>
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#include <linux/notifier.h>
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#include <linux/backing-dev.h>
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#include <linux/memcontrol.h>
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#include <linux/gfp.h>
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#include <linux/uio.h>
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#include <linux/hugetlb.h>
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#include <linux/page_idle.h>
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#include <linux/local_lock.h>
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#include <linux/buffer_head.h>
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#include "internal.h"
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#define CREATE_TRACE_POINTS
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#include <trace/events/pagemap.h>
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/* How many pages do we try to swap or page in/out together? */
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int page_cluster;
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/* Protecting only lru_rotate.pvec which requires disabling interrupts */
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struct lru_rotate {
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local_lock_t lock;
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struct pagevec pvec;
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};
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static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = {
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.lock = INIT_LOCAL_LOCK(lock),
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};
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/*
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* The following struct pagevec are grouped together because they are protected
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* by disabling preemption (and interrupts remain enabled).
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*/
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struct lru_pvecs {
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local_lock_t lock;
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struct pagevec lru_add;
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struct pagevec lru_deactivate_file;
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struct pagevec lru_deactivate;
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struct pagevec lru_lazyfree;
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#ifdef CONFIG_SMP
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struct pagevec activate_page;
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#endif
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};
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static DEFINE_PER_CPU(struct lru_pvecs, lru_pvecs) = {
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.lock = INIT_LOCAL_LOCK(lock),
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};
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/*
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* This path almost never happens for VM activity - pages are normally freed
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* via pagevecs. But it gets used by networking - and for compound pages.
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*/
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static void __page_cache_release(struct page *page)
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{
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if (PageLRU(page)) {
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struct folio *folio = page_folio(page);
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struct lruvec *lruvec;
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unsigned long flags;
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lruvec = folio_lruvec_lock_irqsave(folio, &flags);
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del_page_from_lru_list(page, lruvec);
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__clear_page_lru_flags(page);
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unlock_page_lruvec_irqrestore(lruvec, flags);
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}
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/* See comment on PageMlocked in release_pages() */
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if (unlikely(PageMlocked(page))) {
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int nr_pages = thp_nr_pages(page);
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__ClearPageMlocked(page);
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mod_zone_page_state(page_zone(page), NR_MLOCK, -nr_pages);
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count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages);
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}
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}
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static void __put_single_page(struct page *page)
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{
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__page_cache_release(page);
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mem_cgroup_uncharge(page_folio(page));
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free_unref_page(page, 0);
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}
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static void __put_compound_page(struct page *page)
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{
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/*
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* __page_cache_release() is supposed to be called for thp, not for
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* hugetlb. This is because hugetlb page does never have PageLRU set
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* (it's never listed to any LRU lists) and no memcg routines should
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* be called for hugetlb (it has a separate hugetlb_cgroup.)
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*/
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if (!PageHuge(page))
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__page_cache_release(page);
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destroy_compound_page(page);
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}
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void __put_page(struct page *page)
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{
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if (unlikely(is_zone_device_page(page)))
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free_zone_device_page(page);
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else if (unlikely(PageCompound(page)))
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__put_compound_page(page);
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else
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__put_single_page(page);
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}
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EXPORT_SYMBOL(__put_page);
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/**
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* put_pages_list() - release a list of pages
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* @pages: list of pages threaded on page->lru
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*
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* Release a list of pages which are strung together on page.lru.
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*/
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void put_pages_list(struct list_head *pages)
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{
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struct page *page, *next;
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list_for_each_entry_safe(page, next, pages, lru) {
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if (!put_page_testzero(page)) {
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list_del(&page->lru);
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continue;
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}
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if (PageHead(page)) {
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list_del(&page->lru);
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__put_compound_page(page);
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continue;
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}
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/* Cannot be PageLRU because it's passed to us using the lru */
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}
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free_unref_page_list(pages);
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INIT_LIST_HEAD(pages);
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}
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EXPORT_SYMBOL(put_pages_list);
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/*
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* get_kernel_pages() - pin kernel pages in memory
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* @kiov: An array of struct kvec structures
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* @nr_segs: number of segments to pin
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* @write: pinning for read/write, currently ignored
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* @pages: array that receives pointers to the pages pinned.
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* Should be at least nr_segs long.
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*
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* Returns number of pages pinned. This may be fewer than the number requested.
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* If nr_segs is 0 or negative, returns 0. If no pages were pinned, returns 0.
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* Each page returned must be released with a put_page() call when it is
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* finished with.
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*/
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int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
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struct page **pages)
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{
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int seg;
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for (seg = 0; seg < nr_segs; seg++) {
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if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
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return seg;
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pages[seg] = kmap_to_page(kiov[seg].iov_base);
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get_page(pages[seg]);
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}
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return seg;
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}
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EXPORT_SYMBOL_GPL(get_kernel_pages);
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static void pagevec_lru_move_fn(struct pagevec *pvec,
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void (*move_fn)(struct page *page, struct lruvec *lruvec))
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{
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int i;
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struct lruvec *lruvec = NULL;
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unsigned long flags = 0;
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for (i = 0; i < pagevec_count(pvec); i++) {
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struct page *page = pvec->pages[i];
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struct folio *folio = page_folio(page);
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/* block memcg migration during page moving between lru */
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if (!TestClearPageLRU(page))
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continue;
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lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags);
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(*move_fn)(page, lruvec);
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SetPageLRU(page);
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}
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if (lruvec)
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unlock_page_lruvec_irqrestore(lruvec, flags);
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release_pages(pvec->pages, pvec->nr);
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pagevec_reinit(pvec);
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}
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static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec)
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{
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struct folio *folio = page_folio(page);
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if (!folio_test_unevictable(folio)) {
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lruvec_del_folio(lruvec, folio);
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folio_clear_active(folio);
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lruvec_add_folio_tail(lruvec, folio);
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__count_vm_events(PGROTATED, folio_nr_pages(folio));
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}
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}
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/* return true if pagevec needs to drain */
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static bool pagevec_add_and_need_flush(struct pagevec *pvec, struct page *page)
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{
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bool ret = false;
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if (!pagevec_add(pvec, page) || PageCompound(page) ||
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lru_cache_disabled())
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ret = true;
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return ret;
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}
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/*
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* Writeback is about to end against a folio which has been marked for
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* immediate reclaim. If it still appears to be reclaimable, move it
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* to the tail of the inactive list.
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*
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* folio_rotate_reclaimable() must disable IRQs, to prevent nasty races.
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*/
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void folio_rotate_reclaimable(struct folio *folio)
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{
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if (!folio_test_locked(folio) && !folio_test_dirty(folio) &&
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!folio_test_unevictable(folio) && folio_test_lru(folio)) {
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struct pagevec *pvec;
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unsigned long flags;
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folio_get(folio);
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local_lock_irqsave(&lru_rotate.lock, flags);
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pvec = this_cpu_ptr(&lru_rotate.pvec);
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if (pagevec_add_and_need_flush(pvec, &folio->page))
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pagevec_lru_move_fn(pvec, pagevec_move_tail_fn);
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local_unlock_irqrestore(&lru_rotate.lock, flags);
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}
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}
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void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages)
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{
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do {
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unsigned long lrusize;
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/*
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* Hold lruvec->lru_lock is safe here, since
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* 1) The pinned lruvec in reclaim, or
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* 2) From a pre-LRU page during refault (which also holds the
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* rcu lock, so would be safe even if the page was on the LRU
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* and could move simultaneously to a new lruvec).
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*/
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spin_lock_irq(&lruvec->lru_lock);
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/* Record cost event */
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if (file)
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lruvec->file_cost += nr_pages;
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else
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lruvec->anon_cost += nr_pages;
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/*
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* Decay previous events
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*
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* Because workloads change over time (and to avoid
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* overflow) we keep these statistics as a floating
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* average, which ends up weighing recent refaults
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* more than old ones.
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*/
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lrusize = lruvec_page_state(lruvec, NR_INACTIVE_ANON) +
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lruvec_page_state(lruvec, NR_ACTIVE_ANON) +
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lruvec_page_state(lruvec, NR_INACTIVE_FILE) +
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lruvec_page_state(lruvec, NR_ACTIVE_FILE);
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if (lruvec->file_cost + lruvec->anon_cost > lrusize / 4) {
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lruvec->file_cost /= 2;
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lruvec->anon_cost /= 2;
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}
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spin_unlock_irq(&lruvec->lru_lock);
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} while ((lruvec = parent_lruvec(lruvec)));
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}
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void lru_note_cost_folio(struct folio *folio)
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{
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lru_note_cost(folio_lruvec(folio), folio_is_file_lru(folio),
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folio_nr_pages(folio));
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}
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static void __folio_activate(struct folio *folio, struct lruvec *lruvec)
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{
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if (!folio_test_active(folio) && !folio_test_unevictable(folio)) {
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long nr_pages = folio_nr_pages(folio);
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lruvec_del_folio(lruvec, folio);
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folio_set_active(folio);
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lruvec_add_folio(lruvec, folio);
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trace_mm_lru_activate(folio);
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__count_vm_events(PGACTIVATE, nr_pages);
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__count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE,
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nr_pages);
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}
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}
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#ifdef CONFIG_SMP
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static void __activate_page(struct page *page, struct lruvec *lruvec)
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{
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return __folio_activate(page_folio(page), lruvec);
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}
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static void activate_page_drain(int cpu)
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{
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struct pagevec *pvec = &per_cpu(lru_pvecs.activate_page, cpu);
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if (pagevec_count(pvec))
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pagevec_lru_move_fn(pvec, __activate_page);
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}
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static bool need_activate_page_drain(int cpu)
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{
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return pagevec_count(&per_cpu(lru_pvecs.activate_page, cpu)) != 0;
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}
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static void folio_activate(struct folio *folio)
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{
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if (folio_test_lru(folio) && !folio_test_active(folio) &&
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!folio_test_unevictable(folio)) {
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struct pagevec *pvec;
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folio_get(folio);
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local_lock(&lru_pvecs.lock);
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pvec = this_cpu_ptr(&lru_pvecs.activate_page);
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if (pagevec_add_and_need_flush(pvec, &folio->page))
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pagevec_lru_move_fn(pvec, __activate_page);
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local_unlock(&lru_pvecs.lock);
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}
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}
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#else
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static inline void activate_page_drain(int cpu)
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{
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}
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static void folio_activate(struct folio *folio)
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{
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struct lruvec *lruvec;
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if (folio_test_clear_lru(folio)) {
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lruvec = folio_lruvec_lock_irq(folio);
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__folio_activate(folio, lruvec);
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unlock_page_lruvec_irq(lruvec);
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folio_set_lru(folio);
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}
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}
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#endif
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static void __lru_cache_activate_folio(struct folio *folio)
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{
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struct pagevec *pvec;
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int i;
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local_lock(&lru_pvecs.lock);
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pvec = this_cpu_ptr(&lru_pvecs.lru_add);
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/*
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* Search backwards on the optimistic assumption that the page being
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* activated has just been added to this pagevec. Note that only
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* the local pagevec is examined as a !PageLRU page could be in the
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* process of being released, reclaimed, migrated or on a remote
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* pagevec that is currently being drained. Furthermore, marking
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* a remote pagevec's page PageActive potentially hits a race where
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* a page is marked PageActive just after it is added to the inactive
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* list causing accounting errors and BUG_ON checks to trigger.
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*/
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for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
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struct page *pagevec_page = pvec->pages[i];
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if (pagevec_page == &folio->page) {
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folio_set_active(folio);
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break;
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}
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}
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local_unlock(&lru_pvecs.lock);
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}
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/*
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* Mark a page as having seen activity.
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*
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* inactive,unreferenced -> inactive,referenced
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* inactive,referenced -> active,unreferenced
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* active,unreferenced -> active,referenced
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*
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* When a newly allocated page is not yet visible, so safe for non-atomic ops,
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* __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
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*/
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void folio_mark_accessed(struct folio *folio)
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{
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if (!folio_test_referenced(folio)) {
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folio_set_referenced(folio);
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} else if (folio_test_unevictable(folio)) {
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/*
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* Unevictable pages are on the "LRU_UNEVICTABLE" list. But,
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* this list is never rotated or maintained, so marking an
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* unevictable page accessed has no effect.
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*/
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} else if (!folio_test_active(folio)) {
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/*
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* If the page is on the LRU, queue it for activation via
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* lru_pvecs.activate_page. Otherwise, assume the page is on a
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* pagevec, mark it active and it'll be moved to the active
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* LRU on the next drain.
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*/
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if (folio_test_lru(folio))
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folio_activate(folio);
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else
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__lru_cache_activate_folio(folio);
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folio_clear_referenced(folio);
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workingset_activation(folio);
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}
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if (folio_test_idle(folio))
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folio_clear_idle(folio);
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}
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EXPORT_SYMBOL(folio_mark_accessed);
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/**
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* folio_add_lru - Add a folio to an LRU list.
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* @folio: The folio to be added to the LRU.
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*
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* Queue the folio for addition to the LRU. The decision on whether
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* to add the page to the [in]active [file|anon] list is deferred until the
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* pagevec is drained. This gives a chance for the caller of folio_add_lru()
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* have the folio added to the active list using folio_mark_accessed().
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*/
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void folio_add_lru(struct folio *folio)
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{
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struct pagevec *pvec;
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VM_BUG_ON_FOLIO(folio_test_active(folio) && folio_test_unevictable(folio), folio);
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VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
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folio_get(folio);
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local_lock(&lru_pvecs.lock);
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pvec = this_cpu_ptr(&lru_pvecs.lru_add);
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if (pagevec_add_and_need_flush(pvec, &folio->page))
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__pagevec_lru_add(pvec);
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local_unlock(&lru_pvecs.lock);
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}
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EXPORT_SYMBOL(folio_add_lru);
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/**
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* lru_cache_add_inactive_or_unevictable
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* @page: the page to be added to LRU
|
|
* @vma: vma in which page is mapped for determining reclaimability
|
|
*
|
|
* Place @page on the inactive or unevictable LRU list, depending on its
|
|
* evictability.
|
|
*/
|
|
void lru_cache_add_inactive_or_unevictable(struct page *page,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
VM_BUG_ON_PAGE(PageLRU(page), page);
|
|
|
|
if (unlikely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED))
|
|
mlock_new_page(page);
|
|
else
|
|
lru_cache_add(page);
|
|
}
|
|
|
|
/*
|
|
* If the page can not be invalidated, it is moved to the
|
|
* inactive list to speed up its reclaim. It is moved to the
|
|
* head of the list, rather than the tail, to give the flusher
|
|
* threads some time to write it out, as this is much more
|
|
* effective than the single-page writeout from reclaim.
|
|
*
|
|
* If the page isn't page_mapped and dirty/writeback, the page
|
|
* could reclaim asap using PG_reclaim.
|
|
*
|
|
* 1. active, mapped page -> none
|
|
* 2. active, dirty/writeback page -> inactive, head, PG_reclaim
|
|
* 3. inactive, mapped page -> none
|
|
* 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim
|
|
* 5. inactive, clean -> inactive, tail
|
|
* 6. Others -> none
|
|
*
|
|
* In 4, why it moves inactive's head, the VM expects the page would
|
|
* be write it out by flusher threads as this is much more effective
|
|
* than the single-page writeout from reclaim.
|
|
*/
|
|
static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec)
|
|
{
|
|
bool active = PageActive(page);
|
|
int nr_pages = thp_nr_pages(page);
|
|
|
|
if (PageUnevictable(page))
|
|
return;
|
|
|
|
/* Some processes are using the page */
|
|
if (page_mapped(page))
|
|
return;
|
|
|
|
del_page_from_lru_list(page, lruvec);
|
|
ClearPageActive(page);
|
|
ClearPageReferenced(page);
|
|
|
|
if (PageWriteback(page) || PageDirty(page)) {
|
|
/*
|
|
* PG_reclaim could be raced with end_page_writeback
|
|
* It can make readahead confusing. But race window
|
|
* is _really_ small and it's non-critical problem.
|
|
*/
|
|
add_page_to_lru_list(page, lruvec);
|
|
SetPageReclaim(page);
|
|
} else {
|
|
/*
|
|
* The page's writeback ends up during pagevec
|
|
* We move that page into tail of inactive.
|
|
*/
|
|
add_page_to_lru_list_tail(page, lruvec);
|
|
__count_vm_events(PGROTATED, nr_pages);
|
|
}
|
|
|
|
if (active) {
|
|
__count_vm_events(PGDEACTIVATE, nr_pages);
|
|
__count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
|
|
nr_pages);
|
|
}
|
|
}
|
|
|
|
static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec)
|
|
{
|
|
if (PageActive(page) && !PageUnevictable(page)) {
|
|
int nr_pages = thp_nr_pages(page);
|
|
|
|
del_page_from_lru_list(page, lruvec);
|
|
ClearPageActive(page);
|
|
ClearPageReferenced(page);
|
|
add_page_to_lru_list(page, lruvec);
|
|
|
|
__count_vm_events(PGDEACTIVATE, nr_pages);
|
|
__count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE,
|
|
nr_pages);
|
|
}
|
|
}
|
|
|
|
static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec)
|
|
{
|
|
if (PageAnon(page) && PageSwapBacked(page) &&
|
|
!PageSwapCache(page) && !PageUnevictable(page)) {
|
|
int nr_pages = thp_nr_pages(page);
|
|
|
|
del_page_from_lru_list(page, lruvec);
|
|
ClearPageActive(page);
|
|
ClearPageReferenced(page);
|
|
/*
|
|
* Lazyfree pages are clean anonymous pages. They have
|
|
* PG_swapbacked flag cleared, to distinguish them from normal
|
|
* anonymous pages
|
|
*/
|
|
ClearPageSwapBacked(page);
|
|
add_page_to_lru_list(page, lruvec);
|
|
|
|
__count_vm_events(PGLAZYFREE, nr_pages);
|
|
__count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE,
|
|
nr_pages);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Drain pages out of the cpu's pagevecs.
|
|
* Either "cpu" is the current CPU, and preemption has already been
|
|
* disabled; or "cpu" is being hot-unplugged, and is already dead.
|
|
*/
|
|
void lru_add_drain_cpu(int cpu)
|
|
{
|
|
struct pagevec *pvec = &per_cpu(lru_pvecs.lru_add, cpu);
|
|
|
|
if (pagevec_count(pvec))
|
|
__pagevec_lru_add(pvec);
|
|
|
|
pvec = &per_cpu(lru_rotate.pvec, cpu);
|
|
/* Disabling interrupts below acts as a compiler barrier. */
|
|
if (data_race(pagevec_count(pvec))) {
|
|
unsigned long flags;
|
|
|
|
/* No harm done if a racing interrupt already did this */
|
|
local_lock_irqsave(&lru_rotate.lock, flags);
|
|
pagevec_lru_move_fn(pvec, pagevec_move_tail_fn);
|
|
local_unlock_irqrestore(&lru_rotate.lock, flags);
|
|
}
|
|
|
|
pvec = &per_cpu(lru_pvecs.lru_deactivate_file, cpu);
|
|
if (pagevec_count(pvec))
|
|
pagevec_lru_move_fn(pvec, lru_deactivate_file_fn);
|
|
|
|
pvec = &per_cpu(lru_pvecs.lru_deactivate, cpu);
|
|
if (pagevec_count(pvec))
|
|
pagevec_lru_move_fn(pvec, lru_deactivate_fn);
|
|
|
|
pvec = &per_cpu(lru_pvecs.lru_lazyfree, cpu);
|
|
if (pagevec_count(pvec))
|
|
pagevec_lru_move_fn(pvec, lru_lazyfree_fn);
|
|
|
|
activate_page_drain(cpu);
|
|
}
|
|
|
|
/**
|
|
* deactivate_file_folio() - Forcefully deactivate a file folio.
|
|
* @folio: Folio to deactivate.
|
|
*
|
|
* This function hints to the VM that @folio is a good reclaim candidate,
|
|
* for example if its invalidation fails due to the folio being dirty
|
|
* or under writeback.
|
|
*
|
|
* Context: Caller holds a reference on the page.
|
|
*/
|
|
void deactivate_file_folio(struct folio *folio)
|
|
{
|
|
struct pagevec *pvec;
|
|
|
|
/*
|
|
* In a workload with many unevictable pages such as mprotect,
|
|
* unevictable folio deactivation for accelerating reclaim is pointless.
|
|
*/
|
|
if (folio_test_unevictable(folio))
|
|
return;
|
|
|
|
folio_get(folio);
|
|
local_lock(&lru_pvecs.lock);
|
|
pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate_file);
|
|
|
|
if (pagevec_add_and_need_flush(pvec, &folio->page))
|
|
pagevec_lru_move_fn(pvec, lru_deactivate_file_fn);
|
|
local_unlock(&lru_pvecs.lock);
|
|
}
|
|
|
|
/*
|
|
* deactivate_page - deactivate a page
|
|
* @page: page to deactivate
|
|
*
|
|
* deactivate_page() moves @page to the inactive list if @page was on the active
|
|
* list and was not an unevictable page. This is done to accelerate the reclaim
|
|
* of @page.
|
|
*/
|
|
void deactivate_page(struct page *page)
|
|
{
|
|
if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
|
|
struct pagevec *pvec;
|
|
|
|
local_lock(&lru_pvecs.lock);
|
|
pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate);
|
|
get_page(page);
|
|
if (pagevec_add_and_need_flush(pvec, page))
|
|
pagevec_lru_move_fn(pvec, lru_deactivate_fn);
|
|
local_unlock(&lru_pvecs.lock);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* mark_page_lazyfree - make an anon page lazyfree
|
|
* @page: page to deactivate
|
|
*
|
|
* mark_page_lazyfree() moves @page to the inactive file list.
|
|
* This is done to accelerate the reclaim of @page.
|
|
*/
|
|
void mark_page_lazyfree(struct page *page)
|
|
{
|
|
if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
|
|
!PageSwapCache(page) && !PageUnevictable(page)) {
|
|
struct pagevec *pvec;
|
|
|
|
local_lock(&lru_pvecs.lock);
|
|
pvec = this_cpu_ptr(&lru_pvecs.lru_lazyfree);
|
|
get_page(page);
|
|
if (pagevec_add_and_need_flush(pvec, page))
|
|
pagevec_lru_move_fn(pvec, lru_lazyfree_fn);
|
|
local_unlock(&lru_pvecs.lock);
|
|
}
|
|
}
|
|
|
|
void lru_add_drain(void)
|
|
{
|
|
local_lock(&lru_pvecs.lock);
|
|
lru_add_drain_cpu(smp_processor_id());
|
|
local_unlock(&lru_pvecs.lock);
|
|
mlock_page_drain_local();
|
|
}
|
|
|
|
/*
|
|
* It's called from per-cpu workqueue context in SMP case so
|
|
* lru_add_drain_cpu and invalidate_bh_lrus_cpu should run on
|
|
* the same cpu. It shouldn't be a problem in !SMP case since
|
|
* the core is only one and the locks will disable preemption.
|
|
*/
|
|
static void lru_add_and_bh_lrus_drain(void)
|
|
{
|
|
local_lock(&lru_pvecs.lock);
|
|
lru_add_drain_cpu(smp_processor_id());
|
|
local_unlock(&lru_pvecs.lock);
|
|
invalidate_bh_lrus_cpu();
|
|
mlock_page_drain_local();
|
|
}
|
|
|
|
void lru_add_drain_cpu_zone(struct zone *zone)
|
|
{
|
|
local_lock(&lru_pvecs.lock);
|
|
lru_add_drain_cpu(smp_processor_id());
|
|
drain_local_pages(zone);
|
|
local_unlock(&lru_pvecs.lock);
|
|
mlock_page_drain_local();
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
|
|
static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
|
|
|
|
static void lru_add_drain_per_cpu(struct work_struct *dummy)
|
|
{
|
|
lru_add_and_bh_lrus_drain();
|
|
}
|
|
|
|
/*
|
|
* Doesn't need any cpu hotplug locking because we do rely on per-cpu
|
|
* kworkers being shut down before our page_alloc_cpu_dead callback is
|
|
* executed on the offlined cpu.
|
|
* Calling this function with cpu hotplug locks held can actually lead
|
|
* to obscure indirect dependencies via WQ context.
|
|
*/
|
|
static inline void __lru_add_drain_all(bool force_all_cpus)
|
|
{
|
|
/*
|
|
* lru_drain_gen - Global pages generation number
|
|
*
|
|
* (A) Definition: global lru_drain_gen = x implies that all generations
|
|
* 0 < n <= x are already *scheduled* for draining.
|
|
*
|
|
* This is an optimization for the highly-contended use case where a
|
|
* user space workload keeps constantly generating a flow of pages for
|
|
* each CPU.
|
|
*/
|
|
static unsigned int lru_drain_gen;
|
|
static struct cpumask has_work;
|
|
static DEFINE_MUTEX(lock);
|
|
unsigned cpu, this_gen;
|
|
|
|
/*
|
|
* Make sure nobody triggers this path before mm_percpu_wq is fully
|
|
* initialized.
|
|
*/
|
|
if (WARN_ON(!mm_percpu_wq))
|
|
return;
|
|
|
|
/*
|
|
* Guarantee pagevec counter stores visible by this CPU are visible to
|
|
* other CPUs before loading the current drain generation.
|
|
*/
|
|
smp_mb();
|
|
|
|
/*
|
|
* (B) Locally cache global LRU draining generation number
|
|
*
|
|
* The read barrier ensures that the counter is loaded before the mutex
|
|
* is taken. It pairs with smp_mb() inside the mutex critical section
|
|
* at (D).
|
|
*/
|
|
this_gen = smp_load_acquire(&lru_drain_gen);
|
|
|
|
mutex_lock(&lock);
|
|
|
|
/*
|
|
* (C) Exit the draining operation if a newer generation, from another
|
|
* lru_add_drain_all(), was already scheduled for draining. Check (A).
|
|
*/
|
|
if (unlikely(this_gen != lru_drain_gen && !force_all_cpus))
|
|
goto done;
|
|
|
|
/*
|
|
* (D) Increment global generation number
|
|
*
|
|
* Pairs with smp_load_acquire() at (B), outside of the critical
|
|
* section. Use a full memory barrier to guarantee that the new global
|
|
* drain generation number is stored before loading pagevec counters.
|
|
*
|
|
* This pairing must be done here, before the for_each_online_cpu loop
|
|
* below which drains the page vectors.
|
|
*
|
|
* Let x, y, and z represent some system CPU numbers, where x < y < z.
|
|
* Assume CPU #z is in the middle of the for_each_online_cpu loop
|
|
* below and has already reached CPU #y's per-cpu data. CPU #x comes
|
|
* along, adds some pages to its per-cpu vectors, then calls
|
|
* lru_add_drain_all().
|
|
*
|
|
* If the paired barrier is done at any later step, e.g. after the
|
|
* loop, CPU #x will just exit at (C) and miss flushing out all of its
|
|
* added pages.
|
|
*/
|
|
WRITE_ONCE(lru_drain_gen, lru_drain_gen + 1);
|
|
smp_mb();
|
|
|
|
cpumask_clear(&has_work);
|
|
for_each_online_cpu(cpu) {
|
|
struct work_struct *work = &per_cpu(lru_add_drain_work, cpu);
|
|
|
|
if (pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) ||
|
|
data_race(pagevec_count(&per_cpu(lru_rotate.pvec, cpu))) ||
|
|
pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) ||
|
|
pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) ||
|
|
pagevec_count(&per_cpu(lru_pvecs.lru_lazyfree, cpu)) ||
|
|
need_activate_page_drain(cpu) ||
|
|
need_mlock_page_drain(cpu) ||
|
|
has_bh_in_lru(cpu, NULL)) {
|
|
INIT_WORK(work, lru_add_drain_per_cpu);
|
|
queue_work_on(cpu, mm_percpu_wq, work);
|
|
__cpumask_set_cpu(cpu, &has_work);
|
|
}
|
|
}
|
|
|
|
for_each_cpu(cpu, &has_work)
|
|
flush_work(&per_cpu(lru_add_drain_work, cpu));
|
|
|
|
done:
|
|
mutex_unlock(&lock);
|
|
}
|
|
|
|
void lru_add_drain_all(void)
|
|
{
|
|
__lru_add_drain_all(false);
|
|
}
|
|
#else
|
|
void lru_add_drain_all(void)
|
|
{
|
|
lru_add_drain();
|
|
}
|
|
#endif /* CONFIG_SMP */
|
|
|
|
atomic_t lru_disable_count = ATOMIC_INIT(0);
|
|
|
|
/*
|
|
* lru_cache_disable() needs to be called before we start compiling
|
|
* a list of pages to be migrated using isolate_lru_page().
|
|
* It drains pages on LRU cache and then disable on all cpus until
|
|
* lru_cache_enable is called.
|
|
*
|
|
* Must be paired with a call to lru_cache_enable().
|
|
*/
|
|
void lru_cache_disable(void)
|
|
{
|
|
atomic_inc(&lru_disable_count);
|
|
/*
|
|
* Readers of lru_disable_count are protected by either disabling
|
|
* preemption or rcu_read_lock:
|
|
*
|
|
* preempt_disable, local_irq_disable [bh_lru_lock()]
|
|
* rcu_read_lock [rt_spin_lock CONFIG_PREEMPT_RT]
|
|
* preempt_disable [local_lock !CONFIG_PREEMPT_RT]
|
|
*
|
|
* Since v5.1 kernel, synchronize_rcu() is guaranteed to wait on
|
|
* preempt_disable() regions of code. So any CPU which sees
|
|
* lru_disable_count = 0 will have exited the critical
|
|
* section when synchronize_rcu() returns.
|
|
*/
|
|
synchronize_rcu();
|
|
#ifdef CONFIG_SMP
|
|
__lru_add_drain_all(true);
|
|
#else
|
|
lru_add_and_bh_lrus_drain();
|
|
#endif
|
|
}
|
|
|
|
/**
|
|
* release_pages - batched put_page()
|
|
* @pages: array of pages to release
|
|
* @nr: number of pages
|
|
*
|
|
* Decrement the reference count on all the pages in @pages. If it
|
|
* fell to zero, remove the page from the LRU and free it.
|
|
*/
|
|
void release_pages(struct page **pages, int nr)
|
|
{
|
|
int i;
|
|
LIST_HEAD(pages_to_free);
|
|
struct lruvec *lruvec = NULL;
|
|
unsigned long flags = 0;
|
|
unsigned int lock_batch;
|
|
|
|
for (i = 0; i < nr; i++) {
|
|
struct page *page = pages[i];
|
|
struct folio *folio = page_folio(page);
|
|
|
|
/*
|
|
* Make sure the IRQ-safe lock-holding time does not get
|
|
* excessive with a continuous string of pages from the
|
|
* same lruvec. The lock is held only if lruvec != NULL.
|
|
*/
|
|
if (lruvec && ++lock_batch == SWAP_CLUSTER_MAX) {
|
|
unlock_page_lruvec_irqrestore(lruvec, flags);
|
|
lruvec = NULL;
|
|
}
|
|
|
|
page = &folio->page;
|
|
if (is_huge_zero_page(page))
|
|
continue;
|
|
|
|
if (is_zone_device_page(page)) {
|
|
if (lruvec) {
|
|
unlock_page_lruvec_irqrestore(lruvec, flags);
|
|
lruvec = NULL;
|
|
}
|
|
if (put_devmap_managed_page(page))
|
|
continue;
|
|
if (put_page_testzero(page))
|
|
free_zone_device_page(page);
|
|
continue;
|
|
}
|
|
|
|
if (!put_page_testzero(page))
|
|
continue;
|
|
|
|
if (PageCompound(page)) {
|
|
if (lruvec) {
|
|
unlock_page_lruvec_irqrestore(lruvec, flags);
|
|
lruvec = NULL;
|
|
}
|
|
__put_compound_page(page);
|
|
continue;
|
|
}
|
|
|
|
if (PageLRU(page)) {
|
|
struct lruvec *prev_lruvec = lruvec;
|
|
|
|
lruvec = folio_lruvec_relock_irqsave(folio, lruvec,
|
|
&flags);
|
|
if (prev_lruvec != lruvec)
|
|
lock_batch = 0;
|
|
|
|
del_page_from_lru_list(page, lruvec);
|
|
__clear_page_lru_flags(page);
|
|
}
|
|
|
|
/*
|
|
* In rare cases, when truncation or holepunching raced with
|
|
* munlock after VM_LOCKED was cleared, Mlocked may still be
|
|
* found set here. This does not indicate a problem, unless
|
|
* "unevictable_pgs_cleared" appears worryingly large.
|
|
*/
|
|
if (unlikely(PageMlocked(page))) {
|
|
__ClearPageMlocked(page);
|
|
dec_zone_page_state(page, NR_MLOCK);
|
|
count_vm_event(UNEVICTABLE_PGCLEARED);
|
|
}
|
|
|
|
list_add(&page->lru, &pages_to_free);
|
|
}
|
|
if (lruvec)
|
|
unlock_page_lruvec_irqrestore(lruvec, flags);
|
|
|
|
mem_cgroup_uncharge_list(&pages_to_free);
|
|
free_unref_page_list(&pages_to_free);
|
|
}
|
|
EXPORT_SYMBOL(release_pages);
|
|
|
|
/*
|
|
* The pages which we're about to release may be in the deferred lru-addition
|
|
* queues. That would prevent them from really being freed right now. That's
|
|
* OK from a correctness point of view but is inefficient - those pages may be
|
|
* cache-warm and we want to give them back to the page allocator ASAP.
|
|
*
|
|
* So __pagevec_release() will drain those queues here. __pagevec_lru_add()
|
|
* and __pagevec_lru_add_active() call release_pages() directly to avoid
|
|
* mutual recursion.
|
|
*/
|
|
void __pagevec_release(struct pagevec *pvec)
|
|
{
|
|
if (!pvec->percpu_pvec_drained) {
|
|
lru_add_drain();
|
|
pvec->percpu_pvec_drained = true;
|
|
}
|
|
release_pages(pvec->pages, pagevec_count(pvec));
|
|
pagevec_reinit(pvec);
|
|
}
|
|
EXPORT_SYMBOL(__pagevec_release);
|
|
|
|
static void __pagevec_lru_add_fn(struct folio *folio, struct lruvec *lruvec)
|
|
{
|
|
int was_unevictable = folio_test_clear_unevictable(folio);
|
|
long nr_pages = folio_nr_pages(folio);
|
|
|
|
VM_BUG_ON_FOLIO(folio_test_lru(folio), folio);
|
|
|
|
folio_set_lru(folio);
|
|
/*
|
|
* Is an smp_mb__after_atomic() still required here, before
|
|
* folio_evictable() tests PageMlocked, to rule out the possibility
|
|
* of stranding an evictable folio on an unevictable LRU? I think
|
|
* not, because __munlock_page() only clears PageMlocked while the LRU
|
|
* lock is held.
|
|
*
|
|
* (That is not true of __page_cache_release(), and not necessarily
|
|
* true of release_pages(): but those only clear PageMlocked after
|
|
* put_page_testzero() has excluded any other users of the page.)
|
|
*/
|
|
if (folio_evictable(folio)) {
|
|
if (was_unevictable)
|
|
__count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages);
|
|
} else {
|
|
folio_clear_active(folio);
|
|
folio_set_unevictable(folio);
|
|
/*
|
|
* folio->mlock_count = !!folio_test_mlocked(folio)?
|
|
* But that leaves __mlock_page() in doubt whether another
|
|
* actor has already counted the mlock or not. Err on the
|
|
* safe side, underestimate, let page reclaim fix it, rather
|
|
* than leaving a page on the unevictable LRU indefinitely.
|
|
*/
|
|
folio->mlock_count = 0;
|
|
if (!was_unevictable)
|
|
__count_vm_events(UNEVICTABLE_PGCULLED, nr_pages);
|
|
}
|
|
|
|
lruvec_add_folio(lruvec, folio);
|
|
trace_mm_lru_insertion(folio);
|
|
}
|
|
|
|
/*
|
|
* Add the passed pages to the LRU, then drop the caller's refcount
|
|
* on them. Reinitialises the caller's pagevec.
|
|
*/
|
|
void __pagevec_lru_add(struct pagevec *pvec)
|
|
{
|
|
int i;
|
|
struct lruvec *lruvec = NULL;
|
|
unsigned long flags = 0;
|
|
|
|
for (i = 0; i < pagevec_count(pvec); i++) {
|
|
struct folio *folio = page_folio(pvec->pages[i]);
|
|
|
|
lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags);
|
|
__pagevec_lru_add_fn(folio, lruvec);
|
|
}
|
|
if (lruvec)
|
|
unlock_page_lruvec_irqrestore(lruvec, flags);
|
|
release_pages(pvec->pages, pvec->nr);
|
|
pagevec_reinit(pvec);
|
|
}
|
|
|
|
/**
|
|
* folio_batch_remove_exceptionals() - Prune non-folios from a batch.
|
|
* @fbatch: The batch to prune
|
|
*
|
|
* find_get_entries() fills a batch with both folios and shadow/swap/DAX
|
|
* entries. This function prunes all the non-folio entries from @fbatch
|
|
* without leaving holes, so that it can be passed on to folio-only batch
|
|
* operations.
|
|
*/
|
|
void folio_batch_remove_exceptionals(struct folio_batch *fbatch)
|
|
{
|
|
unsigned int i, j;
|
|
|
|
for (i = 0, j = 0; i < folio_batch_count(fbatch); i++) {
|
|
struct folio *folio = fbatch->folios[i];
|
|
if (!xa_is_value(folio))
|
|
fbatch->folios[j++] = folio;
|
|
}
|
|
fbatch->nr = j;
|
|
}
|
|
|
|
/**
|
|
* pagevec_lookup_range - gang pagecache lookup
|
|
* @pvec: Where the resulting pages are placed
|
|
* @mapping: The address_space to search
|
|
* @start: The starting page index
|
|
* @end: The final page index
|
|
*
|
|
* pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE
|
|
* pages in the mapping starting from index @start and upto index @end
|
|
* (inclusive). The pages are placed in @pvec. pagevec_lookup() takes a
|
|
* reference against the pages in @pvec.
|
|
*
|
|
* The search returns a group of mapping-contiguous pages with ascending
|
|
* indexes. There may be holes in the indices due to not-present pages. We
|
|
* also update @start to index the next page for the traversal.
|
|
*
|
|
* pagevec_lookup_range() returns the number of pages which were found. If this
|
|
* number is smaller than PAGEVEC_SIZE, the end of specified range has been
|
|
* reached.
|
|
*/
|
|
unsigned pagevec_lookup_range(struct pagevec *pvec,
|
|
struct address_space *mapping, pgoff_t *start, pgoff_t end)
|
|
{
|
|
pvec->nr = find_get_pages_range(mapping, start, end, PAGEVEC_SIZE,
|
|
pvec->pages);
|
|
return pagevec_count(pvec);
|
|
}
|
|
EXPORT_SYMBOL(pagevec_lookup_range);
|
|
|
|
unsigned pagevec_lookup_range_tag(struct pagevec *pvec,
|
|
struct address_space *mapping, pgoff_t *index, pgoff_t end,
|
|
xa_mark_t tag)
|
|
{
|
|
pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
|
|
PAGEVEC_SIZE, pvec->pages);
|
|
return pagevec_count(pvec);
|
|
}
|
|
EXPORT_SYMBOL(pagevec_lookup_range_tag);
|
|
|
|
/*
|
|
* Perform any setup for the swap system
|
|
*/
|
|
void __init swap_setup(void)
|
|
{
|
|
unsigned long megs = totalram_pages() >> (20 - PAGE_SHIFT);
|
|
|
|
/* Use a smaller cluster for small-memory machines */
|
|
if (megs < 16)
|
|
page_cluster = 2;
|
|
else
|
|
page_cluster = 3;
|
|
/*
|
|
* Right now other parts of the system means that we
|
|
* _really_ don't want to cluster much more
|
|
*/
|
|
}
|