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![Minchan Kim](/assets/img/avatar_default.png)
Patch series "Introduce MADV_COLD and MADV_PAGEOUT", v7. - Background The Android terminology used for forking a new process and starting an app from scratch is a cold start, while resuming an existing app is a hot start. While we continually try to improve the performance of cold starts, hot starts will always be significantly less power hungry as well as faster so we are trying to make hot start more likely than cold start. To increase hot start, Android userspace manages the order that apps should be killed in a process called ActivityManagerService. ActivityManagerService tracks every Android app or service that the user could be interacting with at any time and translates that into a ranked list for lmkd(low memory killer daemon). They are likely to be killed by lmkd if the system has to reclaim memory. In that sense they are similar to entries in any other cache. Those apps are kept alive for opportunistic performance improvements but those performance improvements will vary based on the memory requirements of individual workloads. - Problem Naturally, cached apps were dominant consumers of memory on the system. However, they were not significant consumers of swap even though they are good candidate for swap. Under investigation, swapping out only begins once the low zone watermark is hit and kswapd wakes up, but the overall allocation rate in the system might trip lmkd thresholds and cause a cached process to be killed(we measured performance swapping out vs. zapping the memory by killing a process. Unsurprisingly, zapping is 10x times faster even though we use zram which is much faster than real storage) so kill from lmkd will often satisfy the high zone watermark, resulting in very few pages actually being moved to swap. - Approach The approach we chose was to use a new interface to allow userspace to proactively reclaim entire processes by leveraging platform information. This allowed us to bypass the inaccuracy of the kernel’s LRUs for pages that are known to be cold from userspace and to avoid races with lmkd by reclaiming apps as soon as they entered the cached state. Additionally, it could provide many chances for platform to use much information to optimize memory efficiency. To achieve the goal, the patchset introduce two new options for madvise. One is MADV_COLD which will deactivate activated pages and the other is MADV_PAGEOUT which will reclaim private pages instantly. These new options complement MADV_DONTNEED and MADV_FREE by adding non-destructive ways to gain some free memory space. MADV_PAGEOUT is similar to MADV_DONTNEED in a way that it hints the kernel that memory region is not currently needed and should be reclaimed immediately; MADV_COLD is similar to MADV_FREE in a way that it hints the kernel that memory region is not currently needed and should be reclaimed when memory pressure rises. This patch (of 5): When a process expects no accesses to a certain memory range, it could give a hint to kernel that the pages can be reclaimed when memory pressure happens but data should be preserved for future use. This could reduce workingset eviction so it ends up increasing performance. This patch introduces the new MADV_COLD hint to madvise(2) syscall. MADV_COLD can be used by a process to mark a memory range as not expected to be used in the near future. The hint can help kernel in deciding which pages to evict early during memory pressure. It works for every LRU pages like MADV_[DONTNEED|FREE]. IOW, It moves active file page -> inactive file LRU active anon page -> inacdtive anon LRU Unlike MADV_FREE, it doesn't move active anonymous pages to inactive file LRU's head because MADV_COLD is a little bit different symantic. MADV_FREE means it's okay to discard when the memory pressure because the content of the page is *garbage* so freeing such pages is almost zero overhead since we don't need to swap out and access afterward causes just minor fault. Thus, it would make sense to put those freeable pages in inactive file LRU to compete other used-once pages. It makes sense for implmentaion point of view, too because it's not swapbacked memory any longer until it would be re-dirtied. Even, it could give a bonus to make them be reclaimed on swapless system. However, MADV_COLD doesn't mean garbage so reclaiming them requires swap-out/in in the end so it's bigger cost. Since we have designed VM LRU aging based on cost-model, anonymous cold pages would be better to position inactive anon's LRU list, not file LRU. Furthermore, it would help to avoid unnecessary scanning if system doesn't have a swap device. Let's start simpler way without adding complexity at this moment. However, keep in mind, too that it's a caveat that workloads with a lot of pages cache are likely to ignore MADV_COLD on anonymous memory because we rarely age anonymous LRU lists. * man-page material MADV_COLD (since Linux x.x) Pages in the specified regions will be treated as less-recently-accessed compared to pages in the system with similar access frequencies. In contrast to MADV_FREE, the contents of the region are preserved regardless of subsequent writes to pages. MADV_COLD cannot be applied to locked pages, Huge TLB pages, or VM_PFNMAP pages. [akpm@linux-foundation.org: resolve conflicts with hmm.git] Link: http://lkml.kernel.org/r/20190726023435.214162-2-minchan@kernel.org Signed-off-by: Minchan Kim <minchan@kernel.org> Reported-by: kbuild test robot <lkp@intel.com> Acked-by: Michal Hocko <mhocko@suse.com> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Cc: James E.J. Bottomley <James.Bottomley@HansenPartnership.com> Cc: Richard Henderson <rth@twiddle.net> Cc: Ralf Baechle <ralf@linux-mips.org> Cc: Chris Zankel <chris@zankel.net> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Daniel Colascione <dancol@google.com> Cc: Dave Hansen <dave.hansen@intel.com> Cc: Hillf Danton <hdanton@sina.com> Cc: Joel Fernandes (Google) <joel@joelfernandes.org> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Oleksandr Natalenko <oleksandr@redhat.com> Cc: Shakeel Butt <shakeelb@google.com> Cc: Sonny Rao <sonnyrao@google.com> Cc: Suren Baghdasaryan <surenb@google.com> Cc: Tim Murray <timmurray@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1085 lines
30 KiB
C
1085 lines
30 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 "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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static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
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static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
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static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
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static DEFINE_PER_CPU(struct pagevec, lru_deactivate_pvecs);
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static DEFINE_PER_CPU(struct pagevec, lru_lazyfree_pvecs);
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#ifdef CONFIG_SMP
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static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
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#endif
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/*
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* This path almost never happens for VM activity - pages are normally
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* freed via pagevecs. But it gets used by networking.
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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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pg_data_t *pgdat = page_pgdat(page);
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struct lruvec *lruvec;
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unsigned long flags;
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spin_lock_irqsave(&pgdat->lru_lock, flags);
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lruvec = mem_cgroup_page_lruvec(page, pgdat);
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VM_BUG_ON_PAGE(!PageLRU(page), page);
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__ClearPageLRU(page);
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del_page_from_lru_list(page, lruvec, page_off_lru(page));
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spin_unlock_irqrestore(&pgdat->lru_lock, flags);
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}
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__ClearPageWaiters(page);
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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);
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free_unref_page(page);
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}
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static void __put_compound_page(struct page *page)
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{
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compound_page_dtor *dtor;
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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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dtor = get_compound_page_dtor(page);
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(*dtor)(page);
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}
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void __put_page(struct page *page)
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{
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if (is_zone_device_page(page)) {
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put_dev_pagemap(page->pgmap);
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/*
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* The page belongs to the device that created pgmap. Do
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* not return it to page allocator.
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*/
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return;
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}
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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. Currently
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* used by read_cache_pages() and related error recovery code.
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*/
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void put_pages_list(struct list_head *pages)
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{
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while (!list_empty(pages)) {
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struct page *victim;
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victim = lru_to_page(pages);
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list_del(&victim->lru);
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put_page(victim);
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}
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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
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* requested. If nr_pages is 0 or negative, returns 0. If no pages
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* were pinned, returns -errno. Each page returned must be released
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* with a put_page() call when it is 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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/*
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* get_kernel_page() - pin a kernel page in memory
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* @start: starting kernel address
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* @write: pinning for read/write, currently ignored
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* @pages: array that receives pointer to the page pinned.
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* Must be at least nr_segs long.
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*
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* Returns 1 if page is pinned. If the page was not pinned, returns
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* -errno. The page returned must be released with a put_page() call
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* when it is finished with.
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*/
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int get_kernel_page(unsigned long start, int write, struct page **pages)
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{
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const struct kvec kiov = {
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.iov_base = (void *)start,
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.iov_len = PAGE_SIZE
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};
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return get_kernel_pages(&kiov, 1, write, pages);
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}
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EXPORT_SYMBOL_GPL(get_kernel_page);
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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, void *arg),
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void *arg)
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{
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int i;
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struct pglist_data *pgdat = NULL;
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struct lruvec *lruvec;
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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 pglist_data *pagepgdat = page_pgdat(page);
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if (pagepgdat != pgdat) {
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if (pgdat)
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spin_unlock_irqrestore(&pgdat->lru_lock, flags);
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pgdat = pagepgdat;
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spin_lock_irqsave(&pgdat->lru_lock, flags);
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}
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lruvec = mem_cgroup_page_lruvec(page, pgdat);
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(*move_fn)(page, lruvec, arg);
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}
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if (pgdat)
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spin_unlock_irqrestore(&pgdat->lru_lock, 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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void *arg)
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{
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int *pgmoved = arg;
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if (PageLRU(page) && !PageUnevictable(page)) {
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del_page_from_lru_list(page, lruvec, page_lru(page));
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ClearPageActive(page);
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add_page_to_lru_list_tail(page, lruvec, page_lru(page));
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(*pgmoved)++;
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}
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}
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/*
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* pagevec_move_tail() must be called with IRQ disabled.
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* Otherwise this may cause nasty races.
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*/
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static void pagevec_move_tail(struct pagevec *pvec)
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{
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int pgmoved = 0;
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pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
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__count_vm_events(PGROTATED, pgmoved);
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}
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/*
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* Writeback is about to end against a page which has been marked for immediate
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* reclaim. If it still appears to be reclaimable, move it to the tail of the
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* inactive list.
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*/
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void rotate_reclaimable_page(struct page *page)
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{
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if (!PageLocked(page) && !PageDirty(page) &&
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!PageUnevictable(page) && PageLRU(page)) {
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struct pagevec *pvec;
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unsigned long flags;
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get_page(page);
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local_irq_save(flags);
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pvec = this_cpu_ptr(&lru_rotate_pvecs);
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if (!pagevec_add(pvec, page) || PageCompound(page))
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pagevec_move_tail(pvec);
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local_irq_restore(flags);
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}
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}
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static void update_page_reclaim_stat(struct lruvec *lruvec,
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int file, int rotated)
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{
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struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
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reclaim_stat->recent_scanned[file]++;
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if (rotated)
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reclaim_stat->recent_rotated[file]++;
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}
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static void __activate_page(struct page *page, struct lruvec *lruvec,
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void *arg)
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{
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if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
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int file = page_is_file_cache(page);
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int lru = page_lru_base_type(page);
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del_page_from_lru_list(page, lruvec, lru);
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SetPageActive(page);
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lru += LRU_ACTIVE;
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add_page_to_lru_list(page, lruvec, lru);
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trace_mm_lru_activate(page);
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__count_vm_event(PGACTIVATE);
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update_page_reclaim_stat(lruvec, file, 1);
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}
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}
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#ifdef CONFIG_SMP
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static void activate_page_drain(int cpu)
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{
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struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
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if (pagevec_count(pvec))
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pagevec_lru_move_fn(pvec, __activate_page, NULL);
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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(activate_page_pvecs, cpu)) != 0;
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}
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void activate_page(struct page *page)
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{
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page = compound_head(page);
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if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
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struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
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get_page(page);
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if (!pagevec_add(pvec, page) || PageCompound(page))
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pagevec_lru_move_fn(pvec, __activate_page, NULL);
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put_cpu_var(activate_page_pvecs);
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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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void activate_page(struct page *page)
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{
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pg_data_t *pgdat = page_pgdat(page);
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page = compound_head(page);
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spin_lock_irq(&pgdat->lru_lock);
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__activate_page(page, mem_cgroup_page_lruvec(page, pgdat), NULL);
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spin_unlock_irq(&pgdat->lru_lock);
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}
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#endif
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static void __lru_cache_activate_page(struct page *page)
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{
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struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
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int i;
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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 == page) {
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SetPageActive(page);
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break;
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}
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}
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put_cpu_var(lru_add_pvec);
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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 mark_page_accessed(struct page *page)
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{
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page = compound_head(page);
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if (!PageActive(page) && !PageUnevictable(page) &&
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PageReferenced(page)) {
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/*
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* If the page is on the LRU, queue it for activation via
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* activate_page_pvecs. 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 (PageLRU(page))
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activate_page(page);
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else
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__lru_cache_activate_page(page);
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ClearPageReferenced(page);
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if (page_is_file_cache(page))
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workingset_activation(page);
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} else if (!PageReferenced(page)) {
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SetPageReferenced(page);
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}
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if (page_is_idle(page))
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clear_page_idle(page);
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}
|
|
EXPORT_SYMBOL(mark_page_accessed);
|
|
|
|
static void __lru_cache_add(struct page *page)
|
|
{
|
|
struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
|
|
|
|
get_page(page);
|
|
if (!pagevec_add(pvec, page) || PageCompound(page))
|
|
__pagevec_lru_add(pvec);
|
|
put_cpu_var(lru_add_pvec);
|
|
}
|
|
|
|
/**
|
|
* lru_cache_add_anon - add a page to the page lists
|
|
* @page: the page to add
|
|
*/
|
|
void lru_cache_add_anon(struct page *page)
|
|
{
|
|
if (PageActive(page))
|
|
ClearPageActive(page);
|
|
__lru_cache_add(page);
|
|
}
|
|
|
|
void lru_cache_add_file(struct page *page)
|
|
{
|
|
if (PageActive(page))
|
|
ClearPageActive(page);
|
|
__lru_cache_add(page);
|
|
}
|
|
EXPORT_SYMBOL(lru_cache_add_file);
|
|
|
|
/**
|
|
* lru_cache_add - add a page to a page list
|
|
* @page: the page to be added to the LRU.
|
|
*
|
|
* Queue the page for addition to the LRU via pagevec. The decision on whether
|
|
* to add the page to the [in]active [file|anon] list is deferred until the
|
|
* pagevec is drained. This gives a chance for the caller of lru_cache_add()
|
|
* have the page added to the active list using mark_page_accessed().
|
|
*/
|
|
void lru_cache_add(struct page *page)
|
|
{
|
|
VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page);
|
|
VM_BUG_ON_PAGE(PageLRU(page), page);
|
|
__lru_cache_add(page);
|
|
}
|
|
|
|
/**
|
|
* lru_cache_add_active_or_unevictable
|
|
* @page: the page to be added to LRU
|
|
* @vma: vma in which page is mapped for determining reclaimability
|
|
*
|
|
* Place @page on the active or unevictable LRU list, depending on its
|
|
* evictability. Note that if the page is not evictable, it goes
|
|
* directly back onto it's zone's unevictable list, it does NOT use a
|
|
* per cpu pagevec.
|
|
*/
|
|
void lru_cache_add_active_or_unevictable(struct page *page,
|
|
struct vm_area_struct *vma)
|
|
{
|
|
VM_BUG_ON_PAGE(PageLRU(page), page);
|
|
|
|
if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
|
|
SetPageActive(page);
|
|
else if (!TestSetPageMlocked(page)) {
|
|
/*
|
|
* We use the irq-unsafe __mod_zone_page_stat because this
|
|
* counter is not modified from interrupt context, and the pte
|
|
* lock is held(spinlock), which implies preemption disabled.
|
|
*/
|
|
__mod_zone_page_state(page_zone(page), NR_MLOCK,
|
|
hpage_nr_pages(page));
|
|
count_vm_event(UNEVICTABLE_PGMLOCKED);
|
|
}
|
|
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,
|
|
void *arg)
|
|
{
|
|
int lru, file;
|
|
bool active;
|
|
|
|
if (!PageLRU(page))
|
|
return;
|
|
|
|
if (PageUnevictable(page))
|
|
return;
|
|
|
|
/* Some processes are using the page */
|
|
if (page_mapped(page))
|
|
return;
|
|
|
|
active = PageActive(page);
|
|
file = page_is_file_cache(page);
|
|
lru = page_lru_base_type(page);
|
|
|
|
del_page_from_lru_list(page, lruvec, lru + active);
|
|
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, lru);
|
|
SetPageReclaim(page);
|
|
} else {
|
|
/*
|
|
* The page's writeback ends up during pagevec
|
|
* We moves tha page into tail of inactive.
|
|
*/
|
|
add_page_to_lru_list_tail(page, lruvec, lru);
|
|
__count_vm_event(PGROTATED);
|
|
}
|
|
|
|
if (active)
|
|
__count_vm_event(PGDEACTIVATE);
|
|
update_page_reclaim_stat(lruvec, file, 0);
|
|
}
|
|
|
|
static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec,
|
|
void *arg)
|
|
{
|
|
if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) {
|
|
int file = page_is_file_cache(page);
|
|
int lru = page_lru_base_type(page);
|
|
|
|
del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE);
|
|
ClearPageActive(page);
|
|
ClearPageReferenced(page);
|
|
add_page_to_lru_list(page, lruvec, lru);
|
|
|
|
__count_vm_events(PGDEACTIVATE, hpage_nr_pages(page));
|
|
update_page_reclaim_stat(lruvec, file, 0);
|
|
}
|
|
}
|
|
|
|
static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec,
|
|
void *arg)
|
|
{
|
|
if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) &&
|
|
!PageSwapCache(page) && !PageUnevictable(page)) {
|
|
bool active = PageActive(page);
|
|
|
|
del_page_from_lru_list(page, lruvec,
|
|
LRU_INACTIVE_ANON + active);
|
|
ClearPageActive(page);
|
|
ClearPageReferenced(page);
|
|
/*
|
|
* lazyfree pages are clean anonymous pages. They have
|
|
* SwapBacked flag cleared to distinguish normal anonymous
|
|
* pages
|
|
*/
|
|
ClearPageSwapBacked(page);
|
|
add_page_to_lru_list(page, lruvec, LRU_INACTIVE_FILE);
|
|
|
|
__count_vm_events(PGLAZYFREE, hpage_nr_pages(page));
|
|
count_memcg_page_event(page, PGLAZYFREE);
|
|
update_page_reclaim_stat(lruvec, 1, 0);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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_add_pvec, cpu);
|
|
|
|
if (pagevec_count(pvec))
|
|
__pagevec_lru_add(pvec);
|
|
|
|
pvec = &per_cpu(lru_rotate_pvecs, cpu);
|
|
if (pagevec_count(pvec)) {
|
|
unsigned long flags;
|
|
|
|
/* No harm done if a racing interrupt already did this */
|
|
local_irq_save(flags);
|
|
pagevec_move_tail(pvec);
|
|
local_irq_restore(flags);
|
|
}
|
|
|
|
pvec = &per_cpu(lru_deactivate_file_pvecs, cpu);
|
|
if (pagevec_count(pvec))
|
|
pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
|
|
|
|
pvec = &per_cpu(lru_deactivate_pvecs, cpu);
|
|
if (pagevec_count(pvec))
|
|
pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
|
|
|
|
pvec = &per_cpu(lru_lazyfree_pvecs, cpu);
|
|
if (pagevec_count(pvec))
|
|
pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
|
|
|
|
activate_page_drain(cpu);
|
|
}
|
|
|
|
/**
|
|
* deactivate_file_page - forcefully deactivate a file page
|
|
* @page: page to deactivate
|
|
*
|
|
* This function hints the VM that @page is a good reclaim candidate,
|
|
* for example if its invalidation fails due to the page being dirty
|
|
* or under writeback.
|
|
*/
|
|
void deactivate_file_page(struct page *page)
|
|
{
|
|
/*
|
|
* In a workload with many unevictable page such as mprotect,
|
|
* unevictable page deactivation for accelerating reclaim is pointless.
|
|
*/
|
|
if (PageUnevictable(page))
|
|
return;
|
|
|
|
if (likely(get_page_unless_zero(page))) {
|
|
struct pagevec *pvec = &get_cpu_var(lru_deactivate_file_pvecs);
|
|
|
|
if (!pagevec_add(pvec, page) || PageCompound(page))
|
|
pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
|
|
put_cpu_var(lru_deactivate_file_pvecs);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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 = &get_cpu_var(lru_deactivate_pvecs);
|
|
|
|
get_page(page);
|
|
if (!pagevec_add(pvec, page) || PageCompound(page))
|
|
pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
|
|
put_cpu_var(lru_deactivate_pvecs);
|
|
}
|
|
}
|
|
|
|
/**
|
|
* 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 = &get_cpu_var(lru_lazyfree_pvecs);
|
|
|
|
get_page(page);
|
|
if (!pagevec_add(pvec, page) || PageCompound(page))
|
|
pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL);
|
|
put_cpu_var(lru_lazyfree_pvecs);
|
|
}
|
|
}
|
|
|
|
void lru_add_drain(void)
|
|
{
|
|
lru_add_drain_cpu(get_cpu());
|
|
put_cpu();
|
|
}
|
|
|
|
#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_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.
|
|
*/
|
|
void lru_add_drain_all(void)
|
|
{
|
|
static DEFINE_MUTEX(lock);
|
|
static struct cpumask has_work;
|
|
int cpu;
|
|
|
|
/*
|
|
* Make sure nobody triggers this path before mm_percpu_wq is fully
|
|
* initialized.
|
|
*/
|
|
if (WARN_ON(!mm_percpu_wq))
|
|
return;
|
|
|
|
mutex_lock(&lock);
|
|
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_add_pvec, cpu)) ||
|
|
pagevec_count(&per_cpu(lru_rotate_pvecs, cpu)) ||
|
|
pagevec_count(&per_cpu(lru_deactivate_file_pvecs, cpu)) ||
|
|
pagevec_count(&per_cpu(lru_deactivate_pvecs, cpu)) ||
|
|
pagevec_count(&per_cpu(lru_lazyfree_pvecs, cpu)) ||
|
|
need_activate_page_drain(cpu)) {
|
|
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));
|
|
|
|
mutex_unlock(&lock);
|
|
}
|
|
#else
|
|
void lru_add_drain_all(void)
|
|
{
|
|
lru_add_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 pglist_data *locked_pgdat = NULL;
|
|
struct lruvec *lruvec;
|
|
unsigned long uninitialized_var(flags);
|
|
unsigned int uninitialized_var(lock_batch);
|
|
|
|
for (i = 0; i < nr; i++) {
|
|
struct page *page = pages[i];
|
|
|
|
/*
|
|
* Make sure the IRQ-safe lock-holding time does not get
|
|
* excessive with a continuous string of pages from the
|
|
* same pgdat. The lock is held only if pgdat != NULL.
|
|
*/
|
|
if (locked_pgdat && ++lock_batch == SWAP_CLUSTER_MAX) {
|
|
spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
|
|
locked_pgdat = NULL;
|
|
}
|
|
|
|
if (is_huge_zero_page(page))
|
|
continue;
|
|
|
|
if (is_zone_device_page(page)) {
|
|
if (locked_pgdat) {
|
|
spin_unlock_irqrestore(&locked_pgdat->lru_lock,
|
|
flags);
|
|
locked_pgdat = NULL;
|
|
}
|
|
/*
|
|
* ZONE_DEVICE pages that return 'false' from
|
|
* put_devmap_managed_page() do not require special
|
|
* processing, and instead, expect a call to
|
|
* put_page_testzero().
|
|
*/
|
|
if (put_devmap_managed_page(page))
|
|
continue;
|
|
}
|
|
|
|
page = compound_head(page);
|
|
if (!put_page_testzero(page))
|
|
continue;
|
|
|
|
if (PageCompound(page)) {
|
|
if (locked_pgdat) {
|
|
spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags);
|
|
locked_pgdat = NULL;
|
|
}
|
|
__put_compound_page(page);
|
|
continue;
|
|
}
|
|
|
|
if (PageLRU(page)) {
|
|
struct pglist_data *pgdat = page_pgdat(page);
|
|
|
|
if (pgdat != locked_pgdat) {
|
|
if (locked_pgdat)
|
|
spin_unlock_irqrestore(&locked_pgdat->lru_lock,
|
|
flags);
|
|
lock_batch = 0;
|
|
locked_pgdat = pgdat;
|
|
spin_lock_irqsave(&locked_pgdat->lru_lock, flags);
|
|
}
|
|
|
|
lruvec = mem_cgroup_page_lruvec(page, locked_pgdat);
|
|
VM_BUG_ON_PAGE(!PageLRU(page), page);
|
|
__ClearPageLRU(page);
|
|
del_page_from_lru_list(page, lruvec, page_off_lru(page));
|
|
}
|
|
|
|
/* Clear Active bit in case of parallel mark_page_accessed */
|
|
__ClearPageActive(page);
|
|
__ClearPageWaiters(page);
|
|
|
|
list_add(&page->lru, &pages_to_free);
|
|
}
|
|
if (locked_pgdat)
|
|
spin_unlock_irqrestore(&locked_pgdat->lru_lock, 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);
|
|
|
|
#ifdef CONFIG_TRANSPARENT_HUGEPAGE
|
|
/* used by __split_huge_page_refcount() */
|
|
void lru_add_page_tail(struct page *page, struct page *page_tail,
|
|
struct lruvec *lruvec, struct list_head *list)
|
|
{
|
|
const int file = 0;
|
|
|
|
VM_BUG_ON_PAGE(!PageHead(page), page);
|
|
VM_BUG_ON_PAGE(PageCompound(page_tail), page);
|
|
VM_BUG_ON_PAGE(PageLRU(page_tail), page);
|
|
lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock);
|
|
|
|
if (!list)
|
|
SetPageLRU(page_tail);
|
|
|
|
if (likely(PageLRU(page)))
|
|
list_add_tail(&page_tail->lru, &page->lru);
|
|
else if (list) {
|
|
/* page reclaim is reclaiming a huge page */
|
|
get_page(page_tail);
|
|
list_add_tail(&page_tail->lru, list);
|
|
} else {
|
|
/*
|
|
* Head page has not yet been counted, as an hpage,
|
|
* so we must account for each subpage individually.
|
|
*
|
|
* Put page_tail on the list at the correct position
|
|
* so they all end up in order.
|
|
*/
|
|
add_page_to_lru_list_tail(page_tail, lruvec,
|
|
page_lru(page_tail));
|
|
}
|
|
|
|
if (!PageUnevictable(page))
|
|
update_page_reclaim_stat(lruvec, file, PageActive(page_tail));
|
|
}
|
|
#endif /* CONFIG_TRANSPARENT_HUGEPAGE */
|
|
|
|
static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec,
|
|
void *arg)
|
|
{
|
|
enum lru_list lru;
|
|
int was_unevictable = TestClearPageUnevictable(page);
|
|
|
|
VM_BUG_ON_PAGE(PageLRU(page), page);
|
|
|
|
SetPageLRU(page);
|
|
/*
|
|
* Page becomes evictable in two ways:
|
|
* 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()].
|
|
* 2) Before acquiring LRU lock to put the page to correct LRU and then
|
|
* a) do PageLRU check with lock [check_move_unevictable_pages]
|
|
* b) do PageLRU check before lock [clear_page_mlock]
|
|
*
|
|
* (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need
|
|
* following strict ordering:
|
|
*
|
|
* #0: __pagevec_lru_add_fn #1: clear_page_mlock
|
|
*
|
|
* SetPageLRU() TestClearPageMlocked()
|
|
* smp_mb() // explicit ordering // above provides strict
|
|
* // ordering
|
|
* PageMlocked() PageLRU()
|
|
*
|
|
*
|
|
* if '#1' does not observe setting of PG_lru by '#0' and fails
|
|
* isolation, the explicit barrier will make sure that page_evictable
|
|
* check will put the page in correct LRU. Without smp_mb(), SetPageLRU
|
|
* can be reordered after PageMlocked check and can make '#1' to fail
|
|
* the isolation of the page whose Mlocked bit is cleared (#0 is also
|
|
* looking at the same page) and the evictable page will be stranded
|
|
* in an unevictable LRU.
|
|
*/
|
|
smp_mb();
|
|
|
|
if (page_evictable(page)) {
|
|
lru = page_lru(page);
|
|
update_page_reclaim_stat(lruvec, page_is_file_cache(page),
|
|
PageActive(page));
|
|
if (was_unevictable)
|
|
count_vm_event(UNEVICTABLE_PGRESCUED);
|
|
} else {
|
|
lru = LRU_UNEVICTABLE;
|
|
ClearPageActive(page);
|
|
SetPageUnevictable(page);
|
|
if (!was_unevictable)
|
|
count_vm_event(UNEVICTABLE_PGCULLED);
|
|
}
|
|
|
|
add_page_to_lru_list(page, lruvec, lru);
|
|
trace_mm_lru_insertion(page, lru);
|
|
}
|
|
|
|
/*
|
|
* 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)
|
|
{
|
|
pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL);
|
|
}
|
|
EXPORT_SYMBOL(__pagevec_lru_add);
|
|
|
|
/**
|
|
* pagevec_lookup_entries - gang pagecache lookup
|
|
* @pvec: Where the resulting entries are placed
|
|
* @mapping: The address_space to search
|
|
* @start: The starting entry index
|
|
* @nr_entries: The maximum number of pages
|
|
* @indices: The cache indices corresponding to the entries in @pvec
|
|
*
|
|
* pagevec_lookup_entries() will search for and return a group of up
|
|
* to @nr_pages pages and shadow entries in the mapping. All
|
|
* entries are placed in @pvec. pagevec_lookup_entries() takes a
|
|
* reference against actual pages in @pvec.
|
|
*
|
|
* The search returns a group of mapping-contiguous entries with
|
|
* ascending indexes. There may be holes in the indices due to
|
|
* not-present entries.
|
|
*
|
|
* pagevec_lookup_entries() returns the number of entries which were
|
|
* found.
|
|
*/
|
|
unsigned pagevec_lookup_entries(struct pagevec *pvec,
|
|
struct address_space *mapping,
|
|
pgoff_t start, unsigned nr_entries,
|
|
pgoff_t *indices)
|
|
{
|
|
pvec->nr = find_get_entries(mapping, start, nr_entries,
|
|
pvec->pages, indices);
|
|
return pagevec_count(pvec);
|
|
}
|
|
|
|
/**
|
|
* pagevec_remove_exceptionals - pagevec exceptionals pruning
|
|
* @pvec: The pagevec to prune
|
|
*
|
|
* pagevec_lookup_entries() fills both pages and exceptional radix
|
|
* tree entries into the pagevec. This function prunes all
|
|
* exceptionals from @pvec without leaving holes, so that it can be
|
|
* passed on to page-only pagevec operations.
|
|
*/
|
|
void pagevec_remove_exceptionals(struct pagevec *pvec)
|
|
{
|
|
int i, j;
|
|
|
|
for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
|
|
struct page *page = pvec->pages[i];
|
|
if (!xa_is_value(page))
|
|
pvec->pages[j++] = page;
|
|
}
|
|
pvec->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);
|
|
|
|
unsigned pagevec_lookup_range_nr_tag(struct pagevec *pvec,
|
|
struct address_space *mapping, pgoff_t *index, pgoff_t end,
|
|
xa_mark_t tag, unsigned max_pages)
|
|
{
|
|
pvec->nr = find_get_pages_range_tag(mapping, index, end, tag,
|
|
min_t(unsigned int, max_pages, PAGEVEC_SIZE), pvec->pages);
|
|
return pagevec_count(pvec);
|
|
}
|
|
EXPORT_SYMBOL(pagevec_lookup_range_nr_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
|
|
*/
|
|
}
|