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-rw-r--r--mm/swap.c1162
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diff --git a/mm/swap.c b/mm/swap.c
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+/*
+ * linux/mm/swap.c
+ *
+ * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
+ */
+
+/*
+ * This file contains the default values for the operation of the
+ * Linux VM subsystem. Fine-tuning documentation can be found in
+ * Documentation/sysctl/vm.txt.
+ * Started 18.12.91
+ * Swap aging added 23.2.95, Stephen Tweedie.
+ * Buffermem limits added 12.3.98, Rik van Riel.
+ */
+
+#include <linux/mm.h>
+#include <linux/sched.h>
+#include <linux/kernel_stat.h>
+#include <linux/swap.h>
+#include <linux/mman.h>
+#include <linux/pagemap.h>
+#include <linux/pagevec.h>
+#include <linux/init.h>
+#include <linux/export.h>
+#include <linux/mm_inline.h>
+#include <linux/percpu_counter.h>
+#include <linux/percpu.h>
+#include <linux/cpu.h>
+#include <linux/notifier.h>
+#include <linux/backing-dev.h>
+#include <linux/memcontrol.h>
+#include <linux/gfp.h>
+#include <linux/uio.h>
+#include <linux/hugetlb.h>
+
+#include "internal.h"
+
+#define CREATE_TRACE_POINTS
+#include <trace/events/pagemap.h>
+
+/* How many pages do we try to swap or page in/out together? */
+int page_cluster;
+
+static DEFINE_PER_CPU(struct pagevec, lru_add_pvec);
+static DEFINE_PER_CPU(struct pagevec, lru_rotate_pvecs);
+static DEFINE_PER_CPU(struct pagevec, lru_deactivate_file_pvecs);
+
+/*
+ * This path almost never happens for VM activity - pages are normally
+ * freed via pagevecs. But it gets used by networking.
+ */
+static void __page_cache_release(struct page *page)
+{
+ if (PageLRU(page)) {
+ struct zone *zone = page_zone(page);
+ struct lruvec *lruvec;
+ unsigned long flags;
+
+ 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));
+ spin_unlock_irqrestore(&zone->lru_lock, flags);
+ }
+ mem_cgroup_uncharge(page);
+}
+
+static void __put_single_page(struct page *page)
+{
+ __page_cache_release(page);
+ free_hot_cold_page(page, false);
+}
+
+static void __put_compound_page(struct page *page)
+{
+ compound_page_dtor *dtor;
+
+ /*
+ * __page_cache_release() is supposed to be called for thp, not for
+ * hugetlb. This is because hugetlb page does never have PageLRU set
+ * (it's never listed to any LRU lists) and no memcg routines should
+ * be called for hugetlb (it has a separate hugetlb_cgroup.)
+ */
+ if (!PageHuge(page))
+ __page_cache_release(page);
+ dtor = get_compound_page_dtor(page);
+ (*dtor)(page);
+}
+
+/**
+ * Two special cases here: we could avoid taking compound_lock_irqsave
+ * and could skip the tail refcounting(in _mapcount).
+ *
+ * 1. Hugetlbfs page:
+ *
+ * PageHeadHuge will remain true until the compound page
+ * is released and enters the buddy allocator, and it could
+ * not be split by __split_huge_page_refcount().
+ *
+ * So if we see PageHeadHuge set, and we have the tail page pin,
+ * then we could safely put head page.
+ *
+ * 2. Slab THP page:
+ *
+ * PG_slab is cleared before the slab frees the head page, and
+ * tail pin cannot be the last reference left on the head page,
+ * because the slab code is free to reuse the compound page
+ * after a kfree/kmem_cache_free without having to check if
+ * there's any tail pin left. In turn all tail pinsmust be always
+ * released while the head is still pinned by the slab code
+ * and so we know PG_slab will be still set too.
+ *
+ * So if we see PageSlab set, and we have the tail page pin,
+ * then we could safely put head page.
+ */
+static __always_inline
+void put_unrefcounted_compound_page(struct page *page_head, struct page *page)
+{
+ /*
+ * If @page is a THP tail, we must read the tail page
+ * flags after the head page flags. The
+ * __split_huge_page_refcount side enforces write memory barriers
+ * between clearing PageTail and before the head page
+ * can be freed and reallocated.
+ */
+ smp_rmb();
+ if (likely(PageTail(page))) {
+ /*
+ * __split_huge_page_refcount cannot race
+ * here, see the comment above this function.
+ */
+ VM_BUG_ON_PAGE(!PageHead(page_head), page_head);
+ VM_BUG_ON_PAGE(page_mapcount(page) != 0, page);
+ if (put_page_testzero(page_head)) {
+ /*
+ * If this is the tail of a slab THP page,
+ * the tail pin must not be the last reference
+ * held on the page, because the PG_slab cannot
+ * be cleared before all tail pins (which skips
+ * the _mapcount tail refcounting) have been
+ * released.
+ *
+ * If this is the tail of a hugetlbfs page,
+ * the tail pin may be the last reference on
+ * the page instead, because PageHeadHuge will
+ * not go away until the compound page enters
+ * the buddy allocator.
+ */
+ VM_BUG_ON_PAGE(PageSlab(page_head), page_head);
+ __put_compound_page(page_head);
+ }
+ } 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).
+ */
+ if (put_page_testzero(page))
+ __put_single_page(page);
+}
+
+static __always_inline
+void put_refcounted_compound_page(struct page *page_head, struct page *page)
+{
+ if (likely(page != page_head && get_page_unless_zero(page_head))) {
+ unsigned long flags;
+
+ /*
+ * @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);
+ if (unlikely(!PageTail(page))) {
+ /* __split_huge_page_refcount run before us */
+ compound_unlock_irqrestore(page_head, flags);
+ if (put_page_testzero(page_head)) {
+ /*
+ * The @page_head may have been freed
+ * and reallocated as a compound page
+ * of smaller order and then freed
+ * again. All we know is that it
+ * cannot have become: a THP page, a
+ * compound page of higher order, a
+ * tail page. That is because we
+ * still hold the refcount of the
+ * split THP tail and page_head was
+ * the THP head before the split.
+ */
+ if (PageHead(page_head))
+ __put_compound_page(page_head);
+ else
+ __put_single_page(page_head);
+ }
+out_put_single:
+ if (put_page_testzero(page))
+ __put_single_page(page);
+ return;
+ }
+ VM_BUG_ON_PAGE(page_head != page->first_page, page);
+ /*
+ * We can release the refcount taken by
+ * get_page_unless_zero() now that
+ * __split_huge_page_refcount() is blocked on the
+ * compound_lock.
+ */
+ if (put_page_testzero(page_head))
+ VM_BUG_ON_PAGE(1, page_head);
+ /* __split_huge_page_refcount will wait now */
+ VM_BUG_ON_PAGE(page_mapcount(page) <= 0, page);
+ atomic_dec(&page->_mapcount);
+ VM_BUG_ON_PAGE(atomic_read(&page_head->_count) <= 0, page_head);
+ VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page);
+ compound_unlock_irqrestore(page_head, flags);
+
+ if (put_page_testzero(page_head)) {
+ if (PageHead(page_head))
+ __put_compound_page(page_head);
+ else
+ __put_single_page(page_head);
+ }
+ } else {
+ /* @page_head is a dangling pointer */
+ VM_BUG_ON_PAGE(PageTail(page), page);
+ goto out_put_single;
+ }
+}
+
+static void put_compound_page(struct page *page)
+{
+ struct page *page_head;
+
+ /*
+ * We see the PageCompound set and PageTail not set, so @page maybe:
+ * 1. hugetlbfs head page, or
+ * 2. THP head page.
+ */
+ if (likely(!PageTail(page))) {
+ if (put_page_testzero(page)) {
+ /*
+ * By the time all refcounts have been released
+ * split_huge_page cannot run anymore from under us.
+ */
+ if (PageHead(page))
+ __put_compound_page(page);
+ else
+ __put_single_page(page);
+ }
+ return;
+ }
+
+ /*
+ * We see the PageCompound set and PageTail set, so @page maybe:
+ * 1. a tail hugetlbfs page, or
+ * 2. a tail THP page, or
+ * 3. a split THP page.
+ *
+ * Case 3 is possible, as we may race with
+ * __split_huge_page_refcount tearing down a THP page.
+ */
+ page_head = compound_head_by_tail(page);
+ if (!__compound_tail_refcounted(page_head))
+ put_unrefcounted_compound_page(page_head, page);
+ else
+ put_refcounted_compound_page(page_head, page);
+}
+
+void put_page(struct page *page)
+{
+ if (unlikely(PageCompound(page)))
+ put_compound_page(page);
+ else if (put_page_testzero(page))
+ __put_single_page(page);
+}
+EXPORT_SYMBOL(put_page);
+
+/*
+ * This function is exported but must not be called by anything other
+ * than get_page(). It implements the slow path of get_page().
+ */
+bool __get_page_tail(struct page *page)
+{
+ /*
+ * This takes care of get_page() if run on a tail page
+ * returned by one of the get_user_pages/follow_page variants.
+ * get_user_pages/follow_page itself doesn't need the compound
+ * lock because it runs __get_page_tail_foll() under the
+ * proper PT lock that already serializes against
+ * split_huge_page().
+ */
+ unsigned long flags;
+ bool got;
+ struct page *page_head = compound_head(page);
+
+ /* Ref to put_compound_page() comment. */
+ if (!__compound_tail_refcounted(page_head)) {
+ 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);
+ __get_page_tail_foll(page, true);
+ 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);
+
+ __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
+ *
+ * When a newly allocated page is not yet visible, so safe for non-atomic ops,
+ * __SetPageReferenced(page) may be substituted for mark_page_accessed(page).
+ */
+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)
+{
+ 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);
+}
+
+/**
+ * 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);
+}
+
+/**
+ * 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);
+ lru_cache_add(page);
+ return;
+ }
+
+ 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);
+ }
+ add_page_to_unevictable_list(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);
+ 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_file_pvecs, cpu);
+ if (pagevec_count(pvec))
+ pagevec_lru_move_fn(pvec, lru_deactivate_file_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))
+ pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL);
+ put_cpu_var(lru_deactivate_file_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_file_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);
+}
+
+/**
+ * release_pages - batched page_cache_release()
+ * @pages: array of pages to release
+ * @nr: number of pages
+ * @cold: whether the pages are cache cold
+ *
+ * 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, bool cold)
+{
+ int i;
+ LIST_HEAD(pages_to_free);
+ struct zone *zone = 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];
+
+ if (unlikely(PageCompound(page))) {
+ if (zone) {
+ spin_unlock_irqrestore(&zone->lru_lock, flags);
+ zone = NULL;
+ }
+ put_compound_page(page);
+ continue;
+ }
+
+ /*
+ * Make sure the IRQ-safe lock-holding time does not get
+ * excessive with a continuous string of pages from the
+ * same zone. The lock is held only if zone != NULL.
+ */
+ if (zone && ++lock_batch == SWAP_CLUSTER_MAX) {
+ spin_unlock_irqrestore(&zone->lru_lock, flags);
+ zone = NULL;
+ }
+
+ 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);
+ lock_batch = 0;
+ 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);
+
+ mem_cgroup_uncharge_list(&pages_to_free);
+ 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, 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 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;
+
+ for (i = 0; i < MAX_SWAPFILES; i++)
+ spin_lock_init(&swapper_spaces[i].tree_lock);
+#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
+ */
+}
generated by cgit v1.2.3 (git 2.25.1) at 2024-06-06 11:47:36 +0000