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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 <linux/page_idle.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);
- 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 != compound_head(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(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);
- }
- if (page_is_idle(page))
- clear_page_idle(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
- */
- }
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