Currently, put_compound_page() carefully handles tricky cases to avoid racing with compound page releasing or splitting, which makes it quite lenthy (about 200+ lines) and needs deep tab indention, which makes it quite hard to follow and maintain. This patch and the next patch refactor this function. Based on the code skeleton of put_compound_page: put_compound_pge: if !PageTail(page) put head page fastpath; return; /* else PageTail */ page_head = compound_head(page) if !__compound_tail_refcounted(page_head) put head page optimal path; <---(1) return; else put head page slowpath; <--- (2) return; This patch introduces two helpers, put_[un]refcounted_compound_page, handling the code path (1) and code path (2), respectively. They both are tagged __always_inline, thus elmiating function call overhead, making them operating the same way as before. They are almost copied verbatim(except one place, a "goto out_put_single" is expanded), with some comments rephrasing. Signed-off-by: Jianyu Zhan <nasa4836@gmail.com> Cc: Kirill A. Shutemov <kirill.shutemov@linux.intel.com> Cc: Rik van Riel <riel@redhat.com> Cc: Jiang Liu <liuj97@gmail.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Mel Gorman <mgorman@suse.de> Cc: Andrea Arcangeli <aarcange@redhat.com> Cc: Sasha Levin <sasha.levin@oracle.com> Cc: Wanpeng Li <liwanp@linux.vnet.ibm.com> Cc: Hugh Dickins <hughd@google.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
1220 lines
34 KiB
C
1220 lines
34 KiB
C
/*
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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/sysctl/vm.txt.
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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/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 "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_pvecs);
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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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struct zone *zone = page_zone(page);
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struct lruvec *lruvec;
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unsigned long flags;
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spin_lock_irqsave(&zone->lru_lock, flags);
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lruvec = mem_cgroup_page_lruvec(page, zone);
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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(&zone->lru_lock, flags);
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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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free_hot_cold_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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compound_page_dtor *dtor;
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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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/**
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* Two special cases here: we could avoid taking compound_lock_irqsave
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* and could skip the tail refcounting(in _mapcount).
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*
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* 1. Hugetlbfs page:
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*
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* PageHeadHuge will remain true until the compound page
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* is released and enters the buddy allocator, and it could
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* not be split by __split_huge_page_refcount().
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*
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* So if we see PageHeadHuge set, and we have the tail page pin,
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* then we could safely put head page.
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*
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* 2. Slab THP page:
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*
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* PG_slab is cleared before the slab frees the head page, and
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* tail pin cannot be the last reference left on the head page,
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* because the slab code is free to reuse the compound page
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* after a kfree/kmem_cache_free without having to check if
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* there's any tail pin left. In turn all tail pinsmust be always
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* released while the head is still pinned by the slab code
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* and so we know PG_slab will be still set too.
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*
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* So if we see PageSlab set, and we have the tail page pin,
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* then we could safely put head page.
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*/
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static __always_inline
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void put_unrefcounted_compound_page(struct page *page_head, struct page *page)
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{
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/*
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* If @page is a THP tail, we must read the tail page
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* flags after the head page flags. The
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* __split_huge_page_refcount side enforces write memory barriers
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* between clearing PageTail and before the head page
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* can be freed and reallocated.
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*/
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smp_rmb();
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if (likely(PageTail(page))) {
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/*
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* __split_huge_page_refcount cannot race
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* here, see the comment above this function.
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*/
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VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
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VM_BUG_ON_PAGE(page_mapcount(page) != 0, page);
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if (put_page_testzero(page_head)) {
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/*
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* If this is the tail of a slab THP page,
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* the tail pin must not be the last reference
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* held on the page, because the PG_slab cannot
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* be cleared before all tail pins (which skips
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* the _mapcount tail refcounting) have been
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* released.
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*
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* If this is the tail of a hugetlbfs page,
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* the tail pin may be the last reference on
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* the page instead, because PageHeadHuge will
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* not go away until the compound page enters
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* the buddy allocator.
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*/
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VM_BUG_ON_PAGE(PageSlab(page_head), page_head);
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__put_compound_page(page_head);
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}
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} else
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/*
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* __split_huge_page_refcount run before us,
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* @page was a THP tail. The split @page_head
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* has been freed and reallocated as slab or
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* hugetlbfs page of smaller order (only
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* possible if reallocated as slab on x86).
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*/
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if (put_page_testzero(page))
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__put_single_page(page);
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}
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static __always_inline
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void put_refcounted_compound_page(struct page *page_head, struct page *page)
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{
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if (likely(page != page_head && get_page_unless_zero(page_head))) {
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unsigned long flags;
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/*
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* @page_head wasn't a dangling pointer but it may not
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* be a head page anymore by the time we obtain the
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* lock. That is ok as long as it can't be freed from
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* under us.
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*/
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flags = compound_lock_irqsave(page_head);
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if (unlikely(!PageTail(page))) {
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/* __split_huge_page_refcount run before us */
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compound_unlock_irqrestore(page_head, flags);
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if (put_page_testzero(page_head)) {
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/*
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* The @page_head may have been freed
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* and reallocated as a compound page
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* of smaller order and then freed
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* again. All we know is that it
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* cannot have become: a THP page, a
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* compound page of higher order, a
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* tail page. That is because we
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* still hold the refcount of the
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* split THP tail and page_head was
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* the THP head before the split.
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*/
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if (PageHead(page_head))
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__put_compound_page(page_head);
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else
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__put_single_page(page_head);
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}
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out_put_single:
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if (put_page_testzero(page))
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__put_single_page(page);
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return;
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}
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VM_BUG_ON_PAGE(page_head != page->first_page, page);
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/*
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* We can release the refcount taken by
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* get_page_unless_zero() now that
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* __split_huge_page_refcount() is blocked on the
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* compound_lock.
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*/
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if (put_page_testzero(page_head))
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VM_BUG_ON_PAGE(1, page_head);
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/* __split_huge_page_refcount will wait now */
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VM_BUG_ON_PAGE(page_mapcount(page) <= 0, page);
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atomic_dec(&page->_mapcount);
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VM_BUG_ON_PAGE(atomic_read(&page_head->_count) <= 0, page_head);
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VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page);
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compound_unlock_irqrestore(page_head, flags);
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if (put_page_testzero(page_head)) {
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if (PageHead(page_head))
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__put_compound_page(page_head);
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else
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__put_single_page(page_head);
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}
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} else {
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/* @page_head is a dangling pointer */
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VM_BUG_ON_PAGE(PageTail(page), page);
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goto out_put_single;
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}
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}
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static void put_compound_page(struct page *page)
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{
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struct page *page_head;
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if (likely(!PageTail(page))) {
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if (put_page_testzero(page)) {
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/*
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* By the time all refcounts have been released
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* split_huge_page cannot run anymore from under us.
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*/
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if (PageHead(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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return;
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}
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/* __split_huge_page_refcount can run under us */
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page_head = compound_head(page);
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/*
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* THP can not break up slab pages so avoid taking
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* compound_lock() and skip the tail page refcounting (in
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* _mapcount) too. Slab performs non-atomic bit ops on
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* page->flags for better performance. In particular
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* slab_unlock() in slub used to be a hot path. It is still
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* hot on arches that do not support
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* this_cpu_cmpxchg_double().
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*
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* If "page" is part of a slab or hugetlbfs page it cannot be
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* splitted and the head page cannot change from under us. And
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* if "page" is part of a THP page under splitting, if the
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* head page pointed by the THP tail isn't a THP head anymore,
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* we'll find PageTail clear after smp_rmb() and we'll treat
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* it as a single page.
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*/
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if (!__compound_tail_refcounted(page_head)) {
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/*
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* If "page" is a THP tail, we must read the tail page
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* flags after the head page flags. The
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* split_huge_page side enforces write memory barriers
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* between clearing PageTail and before the head page
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* can be freed and reallocated.
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*/
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smp_rmb();
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if (likely(PageTail(page))) {
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/*
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* __split_huge_page_refcount cannot race
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* here.
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*/
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VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
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VM_BUG_ON_PAGE(page_mapcount(page) != 0, page);
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if (put_page_testzero(page_head)) {
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/*
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* If this is the tail of a slab
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* compound page, the tail pin must
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* not be the last reference held on
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* the page, because the PG_slab
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* cannot be cleared before all tail
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* pins (which skips the _mapcount
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* tail refcounting) have been
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* released. For hugetlbfs the tail
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* pin may be the last reference on
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* the page instead, because
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* PageHeadHuge will not go away until
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* the compound page enters the buddy
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* allocator.
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*/
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VM_BUG_ON_PAGE(PageSlab(page_head), page_head);
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__put_compound_page(page_head);
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}
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return;
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} else
|
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/*
|
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* __split_huge_page_refcount run before us,
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* "page" was a THP tail. The split page_head
|
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* has been freed and reallocated as slab or
|
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* hugetlbfs page of smaller order (only
|
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* possible if reallocated as slab on x86).
|
|
*/
|
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goto out_put_single;
|
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}
|
|
|
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if (likely(page != page_head && get_page_unless_zero(page_head))) {
|
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unsigned long flags;
|
|
|
|
/*
|
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* page_head wasn't a dangling pointer but it may not
|
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* be a head page anymore by the time we obtain the
|
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* lock. That is ok as long as it can't be freed from
|
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* under us.
|
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*/
|
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flags = compound_lock_irqsave(page_head);
|
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if (unlikely(!PageTail(page))) {
|
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/* __split_huge_page_refcount run before us */
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compound_unlock_irqrestore(page_head, flags);
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if (put_page_testzero(page_head)) {
|
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/*
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* The head page may have been freed
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* and reallocated as a compound page
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* of smaller order and then freed
|
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* again. All we know is that it
|
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* cannot have become: a THP page, a
|
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* compound page of higher order, a
|
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* tail page. That is because we
|
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* still hold the refcount of the
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* split THP tail and page_head was
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* the THP head before the split.
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*/
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if (PageHead(page_head))
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__put_compound_page(page_head);
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else
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__put_single_page(page_head);
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}
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out_put_single:
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if (put_page_testzero(page))
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__put_single_page(page);
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return;
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}
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VM_BUG_ON_PAGE(page_head != page->first_page, page);
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/*
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* We can release the refcount taken by
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* get_page_unless_zero() now that
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* __split_huge_page_refcount() is blocked on the
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* compound_lock.
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*/
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if (put_page_testzero(page_head))
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VM_BUG_ON_PAGE(1, page_head);
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/* __split_huge_page_refcount will wait now */
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VM_BUG_ON_PAGE(page_mapcount(page) <= 0, page);
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atomic_dec(&page->_mapcount);
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VM_BUG_ON_PAGE(atomic_read(&page_head->_count) <= 0, page_head);
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VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page);
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compound_unlock_irqrestore(page_head, flags);
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if (put_page_testzero(page_head)) {
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if (PageHead(page_head))
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__put_compound_page(page_head);
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else
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__put_single_page(page_head);
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}
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} else {
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/* page_head is a dangling pointer */
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VM_BUG_ON_PAGE(PageTail(page), page);
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goto out_put_single;
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}
|
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}
|
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|
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void put_page(struct page *page)
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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 if (put_page_testzero(page))
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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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* This function is exported but must not be called by anything other
|
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* than get_page(). It implements the slow path of get_page().
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*/
|
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bool __get_page_tail(struct page *page)
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{
|
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/*
|
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* This takes care of get_page() if run on a tail page
|
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* returned by one of the get_user_pages/follow_page variants.
|
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* get_user_pages/follow_page itself doesn't need the compound
|
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* lock because it runs __get_page_tail_foll() under the
|
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* proper PT lock that already serializes against
|
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* split_huge_page().
|
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*/
|
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unsigned long flags;
|
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bool got;
|
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struct page *page_head = compound_head(page);
|
|
|
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/* Ref to put_compound_page() comment. */
|
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if (!__compound_tail_refcounted(page_head)) {
|
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smp_rmb();
|
|
if (likely(PageTail(page))) {
|
|
/*
|
|
* This is a hugetlbfs page or a slab
|
|
* page. __split_huge_page_refcount
|
|
* cannot race here.
|
|
*/
|
|
VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
|
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__get_page_tail_foll(page, true);
|
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return true;
|
|
} else {
|
|
/*
|
|
* __split_huge_page_refcount run
|
|
* before us, "page" was a THP
|
|
* tail. The split page_head has been
|
|
* freed and reallocated as slab or
|
|
* hugetlbfs page of smaller order
|
|
* (only possible if reallocated as
|
|
* slab on x86).
|
|
*/
|
|
return false;
|
|
}
|
|
}
|
|
|
|
got = false;
|
|
if (likely(page != page_head && get_page_unless_zero(page_head))) {
|
|
/*
|
|
* page_head wasn't a dangling pointer but it
|
|
* may not be a head page anymore by the time
|
|
* we obtain the lock. That is ok as long as it
|
|
* can't be freed from under us.
|
|
*/
|
|
flags = compound_lock_irqsave(page_head);
|
|
/* here __split_huge_page_refcount won't run anymore */
|
|
if (likely(PageTail(page))) {
|
|
__get_page_tail_foll(page, false);
|
|
got = true;
|
|
}
|
|
compound_unlock_irqrestore(page_head, flags);
|
|
if (unlikely(!got))
|
|
put_page(page_head);
|
|
}
|
|
return got;
|
|
}
|
|
EXPORT_SYMBOL(__get_page_tail);
|
|
|
|
/**
|
|
* put_pages_list() - release a list of pages
|
|
* @pages: list of pages threaded on page->lru
|
|
*
|
|
* Release a list of pages which are strung together on page.lru. Currently
|
|
* used by read_cache_pages() and related error recovery code.
|
|
*/
|
|
void put_pages_list(struct list_head *pages)
|
|
{
|
|
while (!list_empty(pages)) {
|
|
struct page *victim;
|
|
|
|
victim = list_entry(pages->prev, struct page, lru);
|
|
list_del(&victim->lru);
|
|
page_cache_release(victim);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(put_pages_list);
|
|
|
|
/*
|
|
* get_kernel_pages() - pin kernel pages in memory
|
|
* @kiov: An array of struct kvec structures
|
|
* @nr_segs: number of segments to pin
|
|
* @write: pinning for read/write, currently ignored
|
|
* @pages: array that receives pointers to the pages pinned.
|
|
* Should be at least nr_segs long.
|
|
*
|
|
* Returns number of pages pinned. This may be fewer than the number
|
|
* requested. If nr_pages is 0 or negative, returns 0. If no pages
|
|
* were pinned, returns -errno. Each page returned must be released
|
|
* with a put_page() call when it is finished with.
|
|
*/
|
|
int get_kernel_pages(const struct kvec *kiov, int nr_segs, int write,
|
|
struct page **pages)
|
|
{
|
|
int seg;
|
|
|
|
for (seg = 0; seg < nr_segs; seg++) {
|
|
if (WARN_ON(kiov[seg].iov_len != PAGE_SIZE))
|
|
return seg;
|
|
|
|
pages[seg] = kmap_to_page(kiov[seg].iov_base);
|
|
page_cache_get(pages[seg]);
|
|
}
|
|
|
|
return seg;
|
|
}
|
|
EXPORT_SYMBOL_GPL(get_kernel_pages);
|
|
|
|
/*
|
|
* get_kernel_page() - pin a kernel page in memory
|
|
* @start: starting kernel address
|
|
* @write: pinning for read/write, currently ignored
|
|
* @pages: array that receives pointer to the page pinned.
|
|
* Must be at least nr_segs long.
|
|
*
|
|
* Returns 1 if page is pinned. If the page was not pinned, returns
|
|
* -errno. The page returned must be released with a put_page() call
|
|
* when it is finished with.
|
|
*/
|
|
int get_kernel_page(unsigned long start, int write, struct page **pages)
|
|
{
|
|
const struct kvec kiov = {
|
|
.iov_base = (void *)start,
|
|
.iov_len = PAGE_SIZE
|
|
};
|
|
|
|
return get_kernel_pages(&kiov, 1, write, pages);
|
|
}
|
|
EXPORT_SYMBOL_GPL(get_kernel_page);
|
|
|
|
static void pagevec_lru_move_fn(struct pagevec *pvec,
|
|
void (*move_fn)(struct page *page, struct lruvec *lruvec, void *arg),
|
|
void *arg)
|
|
{
|
|
int i;
|
|
struct zone *zone = NULL;
|
|
struct lruvec *lruvec;
|
|
unsigned long flags = 0;
|
|
|
|
for (i = 0; i < pagevec_count(pvec); i++) {
|
|
struct page *page = pvec->pages[i];
|
|
struct zone *pagezone = page_zone(page);
|
|
|
|
if (pagezone != zone) {
|
|
if (zone)
|
|
spin_unlock_irqrestore(&zone->lru_lock, flags);
|
|
zone = pagezone;
|
|
spin_lock_irqsave(&zone->lru_lock, flags);
|
|
}
|
|
|
|
lruvec = mem_cgroup_page_lruvec(page, zone);
|
|
(*move_fn)(page, lruvec, arg);
|
|
}
|
|
if (zone)
|
|
spin_unlock_irqrestore(&zone->lru_lock, flags);
|
|
release_pages(pvec->pages, pvec->nr, pvec->cold);
|
|
pagevec_reinit(pvec);
|
|
}
|
|
|
|
static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec,
|
|
void *arg)
|
|
{
|
|
int *pgmoved = arg;
|
|
|
|
if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
|
|
enum lru_list lru = page_lru_base_type(page);
|
|
list_move_tail(&page->lru, &lruvec->lists[lru]);
|
|
(*pgmoved)++;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* pagevec_move_tail() must be called with IRQ disabled.
|
|
* Otherwise this may cause nasty races.
|
|
*/
|
|
static void pagevec_move_tail(struct pagevec *pvec)
|
|
{
|
|
int pgmoved = 0;
|
|
|
|
pagevec_lru_move_fn(pvec, pagevec_move_tail_fn, &pgmoved);
|
|
__count_vm_events(PGROTATED, pgmoved);
|
|
}
|
|
|
|
/*
|
|
* Writeback is about to end against a page which has been marked for immediate
|
|
* reclaim. If it still appears to be reclaimable, move it to the tail of the
|
|
* inactive list.
|
|
*/
|
|
void rotate_reclaimable_page(struct page *page)
|
|
{
|
|
if (!PageLocked(page) && !PageDirty(page) && !PageActive(page) &&
|
|
!PageUnevictable(page) && PageLRU(page)) {
|
|
struct pagevec *pvec;
|
|
unsigned long flags;
|
|
|
|
page_cache_get(page);
|
|
local_irq_save(flags);
|
|
pvec = this_cpu_ptr(&lru_rotate_pvecs);
|
|
if (!pagevec_add(pvec, page))
|
|
pagevec_move_tail(pvec);
|
|
local_irq_restore(flags);
|
|
}
|
|
}
|
|
|
|
static void update_page_reclaim_stat(struct lruvec *lruvec,
|
|
int file, int rotated)
|
|
{
|
|
struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
|
|
|
|
reclaim_stat->recent_scanned[file]++;
|
|
if (rotated)
|
|
reclaim_stat->recent_rotated[file]++;
|
|
}
|
|
|
|
static void __activate_page(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);
|
|
SetPageActive(page);
|
|
lru += LRU_ACTIVE;
|
|
add_page_to_lru_list(page, lruvec, lru);
|
|
trace_mm_lru_activate(page, page_to_pfn(page));
|
|
|
|
__count_vm_event(PGACTIVATE);
|
|
update_page_reclaim_stat(lruvec, file, 1);
|
|
}
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
static DEFINE_PER_CPU(struct pagevec, activate_page_pvecs);
|
|
|
|
static void activate_page_drain(int cpu)
|
|
{
|
|
struct pagevec *pvec = &per_cpu(activate_page_pvecs, cpu);
|
|
|
|
if (pagevec_count(pvec))
|
|
pagevec_lru_move_fn(pvec, __activate_page, NULL);
|
|
}
|
|
|
|
static bool need_activate_page_drain(int cpu)
|
|
{
|
|
return pagevec_count(&per_cpu(activate_page_pvecs, cpu)) != 0;
|
|
}
|
|
|
|
void activate_page(struct page *page)
|
|
{
|
|
if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
|
|
struct pagevec *pvec = &get_cpu_var(activate_page_pvecs);
|
|
|
|
page_cache_get(page);
|
|
if (!pagevec_add(pvec, page))
|
|
pagevec_lru_move_fn(pvec, __activate_page, NULL);
|
|
put_cpu_var(activate_page_pvecs);
|
|
}
|
|
}
|
|
|
|
#else
|
|
static inline void activate_page_drain(int cpu)
|
|
{
|
|
}
|
|
|
|
static bool need_activate_page_drain(int cpu)
|
|
{
|
|
return false;
|
|
}
|
|
|
|
void activate_page(struct page *page)
|
|
{
|
|
struct zone *zone = page_zone(page);
|
|
|
|
spin_lock_irq(&zone->lru_lock);
|
|
__activate_page(page, mem_cgroup_page_lruvec(page, zone), NULL);
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
}
|
|
#endif
|
|
|
|
static void __lru_cache_activate_page(struct page *page)
|
|
{
|
|
struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
|
|
int i;
|
|
|
|
/*
|
|
* Search backwards on the optimistic assumption that the page being
|
|
* activated has just been added to this pagevec. Note that only
|
|
* the local pagevec is examined as a !PageLRU page could be in the
|
|
* process of being released, reclaimed, migrated or on a remote
|
|
* pagevec that is currently being drained. Furthermore, marking
|
|
* a remote pagevec's page PageActive potentially hits a race where
|
|
* a page is marked PageActive just after it is added to the inactive
|
|
* list causing accounting errors and BUG_ON checks to trigger.
|
|
*/
|
|
for (i = pagevec_count(pvec) - 1; i >= 0; i--) {
|
|
struct page *pagevec_page = pvec->pages[i];
|
|
|
|
if (pagevec_page == page) {
|
|
SetPageActive(page);
|
|
break;
|
|
}
|
|
}
|
|
|
|
put_cpu_var(lru_add_pvec);
|
|
}
|
|
|
|
/*
|
|
* Mark a page as having seen activity.
|
|
*
|
|
* inactive,unreferenced -> inactive,referenced
|
|
* inactive,referenced -> active,unreferenced
|
|
* active,unreferenced -> active,referenced
|
|
*/
|
|
void mark_page_accessed(struct page *page)
|
|
{
|
|
if (!PageActive(page) && !PageUnevictable(page) &&
|
|
PageReferenced(page)) {
|
|
|
|
/*
|
|
* If the page is on the LRU, queue it for activation via
|
|
* activate_page_pvecs. Otherwise, assume the page is on a
|
|
* pagevec, mark it active and it'll be moved to the active
|
|
* LRU on the next drain.
|
|
*/
|
|
if (PageLRU(page))
|
|
activate_page(page);
|
|
else
|
|
__lru_cache_activate_page(page);
|
|
ClearPageReferenced(page);
|
|
if (page_is_file_cache(page))
|
|
workingset_activation(page);
|
|
} else if (!PageReferenced(page)) {
|
|
SetPageReferenced(page);
|
|
}
|
|
}
|
|
EXPORT_SYMBOL(mark_page_accessed);
|
|
|
|
static void __lru_cache_add(struct page *page)
|
|
{
|
|
struct pagevec *pvec = &get_cpu_var(lru_add_pvec);
|
|
|
|
page_cache_get(page);
|
|
if (!pagevec_space(pvec))
|
|
__pagevec_lru_add(pvec);
|
|
pagevec_add(pvec, page);
|
|
put_cpu_var(lru_add_pvec);
|
|
}
|
|
|
|
/**
|
|
* lru_cache_add: add a page to the page lists
|
|
* @page: the page to add
|
|
*/
|
|
void lru_cache_add_anon(struct page *page)
|
|
{
|
|
ClearPageActive(page);
|
|
__lru_cache_add(page);
|
|
}
|
|
|
|
void lru_cache_add_file(struct page *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);
|
|
}
|
|
|
|
/**
|
|
* add_page_to_unevictable_list - add a page to the unevictable list
|
|
* @page: the page to be added to the unevictable list
|
|
*
|
|
* Add page directly to its zone's unevictable list. To avoid races with
|
|
* tasks that might be making the page evictable, through eg. munlock,
|
|
* munmap or exit, while it's not on the lru, we want to add the page
|
|
* while it's locked or otherwise "invisible" to other tasks. This is
|
|
* difficult to do when using the pagevec cache, so bypass that.
|
|
*/
|
|
void add_page_to_unevictable_list(struct page *page)
|
|
{
|
|
struct zone *zone = page_zone(page);
|
|
struct lruvec *lruvec;
|
|
|
|
spin_lock_irq(&zone->lru_lock);
|
|
lruvec = mem_cgroup_page_lruvec(page, zone);
|
|
ClearPageActive(page);
|
|
SetPageUnevictable(page);
|
|
SetPageLRU(page);
|
|
add_page_to_lru_list(page, lruvec, LRU_UNEVICTABLE);
|
|
spin_unlock_irq(&zone->lru_lock);
|
|
}
|
|
|
|
/*
|
|
* 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_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);
|
|
add_page_to_lru_list(page, lruvec, lru);
|
|
|
|
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.
|
|
*/
|
|
SetPageReclaim(page);
|
|
} else {
|
|
/*
|
|
* The page's writeback ends up during pagevec
|
|
* We moves tha page into tail of inactive.
|
|
*/
|
|
list_move_tail(&page->lru, &lruvec->lists[lru]);
|
|
__count_vm_event(PGROTATED);
|
|
}
|
|
|
|
if (active)
|
|
__count_vm_event(PGDEACTIVATE);
|
|
update_page_reclaim_stat(lruvec, file, 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_pvecs, cpu);
|
|
if (pagevec_count(pvec))
|
|
pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
|
|
|
|
activate_page_drain(cpu);
|
|
}
|
|
|
|
/**
|
|
* deactivate_page - forcefully deactivate a 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_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_pvecs);
|
|
|
|
if (!pagevec_add(pvec, page))
|
|
pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL);
|
|
put_cpu_var(lru_deactivate_pvecs);
|
|
}
|
|
}
|
|
|
|
void lru_add_drain(void)
|
|
{
|
|
lru_add_drain_cpu(get_cpu());
|
|
put_cpu();
|
|
}
|
|
|
|
static void lru_add_drain_per_cpu(struct work_struct *dummy)
|
|
{
|
|
lru_add_drain();
|
|
}
|
|
|
|
static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work);
|
|
|
|
void lru_add_drain_all(void)
|
|
{
|
|
static DEFINE_MUTEX(lock);
|
|
static struct cpumask has_work;
|
|
int cpu;
|
|
|
|
mutex_lock(&lock);
|
|
get_online_cpus();
|
|
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_pvecs, cpu)) ||
|
|
need_activate_page_drain(cpu)) {
|
|
INIT_WORK(work, lru_add_drain_per_cpu);
|
|
schedule_work_on(cpu, work);
|
|
cpumask_set_cpu(cpu, &has_work);
|
|
}
|
|
}
|
|
|
|
for_each_cpu(cpu, &has_work)
|
|
flush_work(&per_cpu(lru_add_drain_work, cpu));
|
|
|
|
put_online_cpus();
|
|
mutex_unlock(&lock);
|
|
}
|
|
|
|
/*
|
|
* Batched page_cache_release(). Decrement the reference count on all the
|
|
* passed pages. If it fell to zero then remove the page from the LRU and
|
|
* free it.
|
|
*
|
|
* Avoid taking zone->lru_lock if possible, but if it is taken, retain it
|
|
* for the remainder of the operation.
|
|
*
|
|
* The locking in this function is against shrink_inactive_list(): we recheck
|
|
* the page count inside the lock to see whether shrink_inactive_list()
|
|
* grabbed the page via the LRU. If it did, give up: shrink_inactive_list()
|
|
* will free it.
|
|
*/
|
|
void release_pages(struct page **pages, int nr, int cold)
|
|
{
|
|
int i;
|
|
LIST_HEAD(pages_to_free);
|
|
struct zone *zone = NULL;
|
|
struct lruvec *lruvec;
|
|
unsigned long uninitialized_var(flags);
|
|
|
|
for (i = 0; i < nr; i++) {
|
|
struct page *page = pages[i];
|
|
|
|
if (unlikely(PageCompound(page))) {
|
|
if (zone) {
|
|
spin_unlock_irqrestore(&zone->lru_lock, flags);
|
|
zone = NULL;
|
|
}
|
|
put_compound_page(page);
|
|
continue;
|
|
}
|
|
|
|
if (!put_page_testzero(page))
|
|
continue;
|
|
|
|
if (PageLRU(page)) {
|
|
struct zone *pagezone = page_zone(page);
|
|
|
|
if (pagezone != zone) {
|
|
if (zone)
|
|
spin_unlock_irqrestore(&zone->lru_lock,
|
|
flags);
|
|
zone = pagezone;
|
|
spin_lock_irqsave(&zone->lru_lock, flags);
|
|
}
|
|
|
|
lruvec = mem_cgroup_page_lruvec(page, zone);
|
|
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);
|
|
|
|
list_add(&page->lru, &pages_to_free);
|
|
}
|
|
if (zone)
|
|
spin_unlock_irqrestore(&zone->lru_lock, flags);
|
|
|
|
free_hot_cold_page_list(&pages_to_free, cold);
|
|
}
|
|
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)
|
|
{
|
|
lru_add_drain();
|
|
release_pages(pvec->pages, pagevec_count(pvec), pvec->cold);
|
|
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);
|
|
VM_BUG_ON(NR_CPUS != 1 &&
|
|
!spin_is_locked(&lruvec_zone(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 {
|
|
struct list_head *list_head;
|
|
/*
|
|
* Head page has not yet been counted, as an hpage,
|
|
* so we must account for each subpage individually.
|
|
*
|
|
* Use the standard add function to put page_tail on the list,
|
|
* but then correct its position so they all end up in order.
|
|
*/
|
|
add_page_to_lru_list(page_tail, lruvec, page_lru(page_tail));
|
|
list_head = page_tail->lru.prev;
|
|
list_move_tail(&page_tail->lru, list_head);
|
|
}
|
|
|
|
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)
|
|
{
|
|
int file = page_is_file_cache(page);
|
|
int active = PageActive(page);
|
|
enum lru_list lru = page_lru(page);
|
|
|
|
VM_BUG_ON_PAGE(PageLRU(page), page);
|
|
|
|
SetPageLRU(page);
|
|
add_page_to_lru_list(page, lruvec, lru);
|
|
update_page_reclaim_stat(lruvec, file, active);
|
|
trace_mm_lru_insertion(page, page_to_pfn(page), lru, trace_pagemap_flags(page));
|
|
}
|
|
|
|
/*
|
|
* 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 entries
|
|
* @indices: The cache indices corresponding to the entries in @pvec
|
|
*
|
|
* pagevec_lookup_entries() will search for and return a group of up
|
|
* to @nr_entries 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_pages,
|
|
pgoff_t *indices)
|
|
{
|
|
pvec->nr = find_get_entries(mapping, start, nr_pages,
|
|
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 (!radix_tree_exceptional_entry(page))
|
|
pvec->pages[j++] = page;
|
|
}
|
|
pvec->nr = j;
|
|
}
|
|
|
|
/**
|
|
* pagevec_lookup - gang pagecache lookup
|
|
* @pvec: Where the resulting pages are placed
|
|
* @mapping: The address_space to search
|
|
* @start: The starting page index
|
|
* @nr_pages: The maximum number of pages
|
|
*
|
|
* pagevec_lookup() will search for and return a group of up to @nr_pages pages
|
|
* in the mapping. 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.
|
|
*
|
|
* pagevec_lookup() returns the number of pages which were found.
|
|
*/
|
|
unsigned pagevec_lookup(struct pagevec *pvec, struct address_space *mapping,
|
|
pgoff_t start, unsigned nr_pages)
|
|
{
|
|
pvec->nr = find_get_pages(mapping, start, nr_pages, pvec->pages);
|
|
return pagevec_count(pvec);
|
|
}
|
|
EXPORT_SYMBOL(pagevec_lookup);
|
|
|
|
unsigned pagevec_lookup_tag(struct pagevec *pvec, struct address_space *mapping,
|
|
pgoff_t *index, int tag, unsigned nr_pages)
|
|
{
|
|
pvec->nr = find_get_pages_tag(mapping, index, tag,
|
|
nr_pages, pvec->pages);
|
|
return pagevec_count(pvec);
|
|
}
|
|
EXPORT_SYMBOL(pagevec_lookup_tag);
|
|
|
|
/*
|
|
* Perform any setup for the swap system
|
|
*/
|
|
void __init swap_setup(void)
|
|
{
|
|
unsigned long megs = totalram_pages >> (20 - PAGE_SHIFT);
|
|
#ifdef CONFIG_SWAP
|
|
int i;
|
|
|
|
if (bdi_init(swapper_spaces[0].backing_dev_info))
|
|
panic("Failed to init swap bdi");
|
|
for (i = 0; i < MAX_SWAPFILES; i++) {
|
|
spin_lock_init(&swapper_spaces[i].tree_lock);
|
|
INIT_LIST_HEAD(&swapper_spaces[i].i_mmap_nonlinear);
|
|
}
|
|
#endif
|
|
|
|
/* 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
|
|
*/
|
|
}
|