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Diffstat (limited to 'mm/swap.c')
| -rw-r--r-- | mm/swap.c | 1215 |
1 files changed, 1215 insertions, 0 deletions
diff --git a/mm/swap.c b/mm/swap.c new file mode 100644 index 000000000..47a47681c --- /dev/null +++ b/mm/swap.c @@ -0,0 +1,1215 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * 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/admin-guide/sysctl/vm.rst. + * 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/memremap.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 <linux/local_lock.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; + +/* Protecting only lru_rotate.pvec which requires disabling interrupts */ +struct lru_rotate { + local_lock_t lock; + struct pagevec pvec; +}; +static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = { + .lock = INIT_LOCAL_LOCK(lock), +}; + +/* + * The following struct pagevec are grouped together because they are protected + * by disabling preemption (and interrupts remain enabled). + */ +struct lru_pvecs { + local_lock_t lock; + struct pagevec lru_add; + struct pagevec lru_deactivate_file; + struct pagevec lru_deactivate; + struct pagevec lru_lazyfree; +#ifdef CONFIG_SMP + struct pagevec activate_page; +#endif +}; +static DEFINE_PER_CPU(struct lru_pvecs, lru_pvecs) = { + .lock = INIT_LOCAL_LOCK(lock), +}; + +/* + * 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)) { + pg_data_t *pgdat = page_pgdat(page); + struct lruvec *lruvec; + unsigned long flags; + + spin_lock_irqsave(&pgdat->lru_lock, flags); + lruvec = mem_cgroup_page_lruvec(page, pgdat); + VM_BUG_ON_PAGE(!PageLRU(page), page); + __ClearPageLRU(page); + del_page_from_lru_list(page, lruvec, page_off_lru(page)); + spin_unlock_irqrestore(&pgdat->lru_lock, flags); + } + __ClearPageWaiters(page); +} + +static void __put_single_page(struct page *page) +{ + __page_cache_release(page); + mem_cgroup_uncharge(page); + free_unref_page(page); +} + +static void __put_compound_page(struct page *page) +{ + /* + * __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); + destroy_compound_page(page); +} + +void __put_page(struct page *page) +{ + if (is_zone_device_page(page)) { + put_dev_pagemap(page->pgmap); + + /* + * The page belongs to the device that created pgmap. Do + * not return it to page allocator. + */ + return; + } + + if (unlikely(PageCompound(page))) + __put_compound_page(page); + else + __put_single_page(page); +} +EXPORT_SYMBOL(__put_page); + +/** + * 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 = lru_to_page(pages); + list_del(&victim->lru); + put_page(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); + get_page(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 pglist_data *pgdat = NULL; + struct lruvec *lruvec; + unsigned long flags = 0; + + for (i = 0; i < pagevec_count(pvec); i++) { + struct page *page = pvec->pages[i]; + struct pglist_data *pagepgdat = page_pgdat(page); + + if (pagepgdat != pgdat) { + if (pgdat) + spin_unlock_irqrestore(&pgdat->lru_lock, flags); + pgdat = pagepgdat; + spin_lock_irqsave(&pgdat->lru_lock, flags); + } + + lruvec = mem_cgroup_page_lruvec(page, pgdat); + (*move_fn)(page, lruvec, arg); + } + if (pgdat) + spin_unlock_irqrestore(&pgdat->lru_lock, flags); + release_pages(pvec->pages, pvec->nr); + pagevec_reinit(pvec); +} + +static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec, + void *arg) +{ + int *pgmoved = arg; + + if (PageLRU(page) && !PageUnevictable(page)) { + del_page_from_lru_list(page, lruvec, page_lru(page)); + ClearPageActive(page); + add_page_to_lru_list_tail(page, lruvec, page_lru(page)); + (*pgmoved) += thp_nr_pages(page); + } +} + +/* + * 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) && + !PageUnevictable(page) && PageLRU(page)) { + struct pagevec *pvec; + unsigned long flags; + + get_page(page); + local_lock_irqsave(&lru_rotate.lock, flags); + pvec = this_cpu_ptr(&lru_rotate.pvec); + if (!pagevec_add(pvec, page) || PageCompound(page)) + pagevec_move_tail(pvec); + local_unlock_irqrestore(&lru_rotate.lock, flags); + } +} + +void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages) +{ + do { + unsigned long lrusize; + + /* Record cost event */ + if (file) + lruvec->file_cost += nr_pages; + else + lruvec->anon_cost += nr_pages; + + /* + * Decay previous events + * + * Because workloads change over time (and to avoid + * overflow) we keep these statistics as a floating + * average, which ends up weighing recent refaults + * more than old ones. + */ + lrusize = lruvec_page_state(lruvec, NR_INACTIVE_ANON) + + lruvec_page_state(lruvec, NR_ACTIVE_ANON) + + lruvec_page_state(lruvec, NR_INACTIVE_FILE) + + lruvec_page_state(lruvec, NR_ACTIVE_FILE); + + if (lruvec->file_cost + lruvec->anon_cost > lrusize / 4) { + lruvec->file_cost /= 2; + lruvec->anon_cost /= 2; + } + } while ((lruvec = parent_lruvec(lruvec))); +} + +void lru_note_cost_page(struct page *page) +{ + lru_note_cost(mem_cgroup_page_lruvec(page, page_pgdat(page)), + page_is_file_lru(page), thp_nr_pages(page)); +} + +static void __activate_page(struct page *page, struct lruvec *lruvec, + void *arg) +{ + if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { + int lru = page_lru_base_type(page); + int nr_pages = thp_nr_pages(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_events(PGACTIVATE, nr_pages); + __count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE, + nr_pages); + } +} + +#ifdef CONFIG_SMP +static void activate_page_drain(int cpu) +{ + struct pagevec *pvec = &per_cpu(lru_pvecs.activate_page, 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(lru_pvecs.activate_page, cpu)) != 0; +} + +static void activate_page(struct page *page) +{ + page = compound_head(page); + if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) { + struct pagevec *pvec; + + local_lock(&lru_pvecs.lock); + pvec = this_cpu_ptr(&lru_pvecs.activate_page); + get_page(page); + if (!pagevec_add(pvec, page) || PageCompound(page)) + pagevec_lru_move_fn(pvec, __activate_page, NULL); + local_unlock(&lru_pvecs.lock); + } +} + +#else +static inline void activate_page_drain(int cpu) +{ +} + +static void activate_page(struct page *page) +{ + pg_data_t *pgdat = page_pgdat(page); + + page = compound_head(page); + spin_lock_irq(&pgdat->lru_lock); + __activate_page(page, mem_cgroup_page_lruvec(page, pgdat), NULL); + spin_unlock_irq(&pgdat->lru_lock); +} +#endif + +static void __lru_cache_activate_page(struct page *page) +{ + struct pagevec *pvec; + int i; + + local_lock(&lru_pvecs.lock); + pvec = this_cpu_ptr(&lru_pvecs.lru_add); + + /* + * 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; + } + } + + local_unlock(&lru_pvecs.lock); +} + +/* + * 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) +{ + page = compound_head(page); + + if (!PageReferenced(page)) { + SetPageReferenced(page); + } else if (PageUnevictable(page)) { + /* + * Unevictable pages are on the "LRU_UNEVICTABLE" list. But, + * this list is never rotated or maintained, so marking an + * evictable page accessed has no effect. + */ + } else if (!PageActive(page)) { + /* + * If the page is on the LRU, queue it for activation via + * lru_pvecs.activate_page. 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); + workingset_activation(page); + } + if (page_is_idle(page)) + clear_page_idle(page); +} +EXPORT_SYMBOL(mark_page_accessed); + +/** + * 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) +{ + struct pagevec *pvec; + + VM_BUG_ON_PAGE(PageActive(page) && PageUnevictable(page), page); + VM_BUG_ON_PAGE(PageLRU(page), page); + + get_page(page); + local_lock(&lru_pvecs.lock); + pvec = this_cpu_ptr(&lru_pvecs.lru_add); + if (!pagevec_add(pvec, page) || PageCompound(page)) + __pagevec_lru_add(pvec); + local_unlock(&lru_pvecs.lock); +} +EXPORT_SYMBOL(lru_cache_add); + +/** + * lru_cache_add_inactive_or_unevictable + * @page: the page to be added to LRU + * @vma: vma in which page is mapped for determining reclaimability + * + * Place @page on the inactive or unevictable LRU list, depending on its + * evictability. + */ +void lru_cache_add_inactive_or_unevictable(struct page *page, + struct vm_area_struct *vma) +{ + bool unevictable; + + VM_BUG_ON_PAGE(PageLRU(page), page); + + unevictable = (vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED; + if (unlikely(unevictable) && !TestSetPageMlocked(page)) { + int nr_pages = thp_nr_pages(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, nr_pages); + count_vm_events(UNEVICTABLE_PGMLOCKED, nr_pages); + } + lru_cache_add(page); +} + +/* + * If the page can not be invalidated, it is moved to the + * inactive list to speed up its reclaim. It is moved to the + * head of the list, rather than the tail, to give the flusher + * threads some time to write it out, as this is much more + * effective than the single-page writeout from reclaim. + * + * If the page isn't page_mapped and dirty/writeback, the page + * could reclaim asap using PG_reclaim. + * + * 1. active, mapped page -> none + * 2. active, dirty/writeback page -> inactive, head, PG_reclaim + * 3. inactive, mapped page -> none + * 4. inactive, dirty/writeback page -> inactive, head, PG_reclaim + * 5. inactive, clean -> inactive, tail + * 6. Others -> none + * + * In 4, why it moves inactive's head, the VM expects the page would + * be write it out by flusher threads as this is much more effective + * than the single-page writeout from reclaim. + */ +static void lru_deactivate_file_fn(struct page *page, struct lruvec *lruvec, + void *arg) +{ + int lru; + bool active; + int nr_pages = thp_nr_pages(page); + + if (!PageLRU(page)) + return; + + if (PageUnevictable(page)) + return; + + /* Some processes are using the page */ + if (page_mapped(page)) + return; + + active = PageActive(page); + lru = page_lru_base_type(page); + + del_page_from_lru_list(page, lruvec, lru + active); + ClearPageActive(page); + ClearPageReferenced(page); + + if (PageWriteback(page) || PageDirty(page)) { + /* + * PG_reclaim could be raced with end_page_writeback + * It can make readahead confusing. But race window + * is _really_ small and it's non-critical problem. + */ + add_page_to_lru_list(page, lruvec, lru); + SetPageReclaim(page); + } else { + /* + * The page's writeback ends up during pagevec + * We moves tha page into tail of inactive. + */ + add_page_to_lru_list_tail(page, lruvec, lru); + __count_vm_events(PGROTATED, nr_pages); + } + + if (active) { + __count_vm_events(PGDEACTIVATE, nr_pages); + __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, + nr_pages); + } +} + +static void lru_deactivate_fn(struct page *page, struct lruvec *lruvec, + void *arg) +{ + if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) { + int lru = page_lru_base_type(page); + int nr_pages = thp_nr_pages(page); + + del_page_from_lru_list(page, lruvec, lru + LRU_ACTIVE); + ClearPageActive(page); + ClearPageReferenced(page); + add_page_to_lru_list(page, lruvec, lru); + + __count_vm_events(PGDEACTIVATE, nr_pages); + __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, + nr_pages); + } +} + +static void lru_lazyfree_fn(struct page *page, struct lruvec *lruvec, + void *arg) +{ + if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) && + !PageSwapCache(page) && !PageUnevictable(page)) { + bool active = PageActive(page); + int nr_pages = thp_nr_pages(page); + + del_page_from_lru_list(page, lruvec, + LRU_INACTIVE_ANON + active); + ClearPageActive(page); + ClearPageReferenced(page); + /* + * Lazyfree pages are clean anonymous pages. They have + * PG_swapbacked flag cleared, to distinguish them from normal + * anonymous pages + */ + ClearPageSwapBacked(page); + add_page_to_lru_list(page, lruvec, LRU_INACTIVE_FILE); + + __count_vm_events(PGLAZYFREE, nr_pages); + __count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE, + nr_pages); + } +} + +/* + * Drain pages out of the cpu's pagevecs. + * Either "cpu" is the current CPU, and preemption has already been + * disabled; or "cpu" is being hot-unplugged, and is already dead. + */ +void lru_add_drain_cpu(int cpu) +{ + struct pagevec *pvec = &per_cpu(lru_pvecs.lru_add, cpu); + + if (pagevec_count(pvec)) + __pagevec_lru_add(pvec); + + pvec = &per_cpu(lru_rotate.pvec, cpu); + /* Disabling interrupts below acts as a compiler barrier. */ + if (data_race(pagevec_count(pvec))) { + unsigned long flags; + + /* No harm done if a racing interrupt already did this */ + local_lock_irqsave(&lru_rotate.lock, flags); + pagevec_move_tail(pvec); + local_unlock_irqrestore(&lru_rotate.lock, flags); + } + + pvec = &per_cpu(lru_pvecs.lru_deactivate_file, cpu); + if (pagevec_count(pvec)) + pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL); + + pvec = &per_cpu(lru_pvecs.lru_deactivate, cpu); + if (pagevec_count(pvec)) + pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); + + pvec = &per_cpu(lru_pvecs.lru_lazyfree, cpu); + if (pagevec_count(pvec)) + pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL); + + activate_page_drain(cpu); +} + +/** + * deactivate_file_page - forcefully deactivate a file page + * @page: page to deactivate + * + * This function hints the VM that @page is a good reclaim candidate, + * for example if its invalidation fails due to the page being dirty + * or under writeback. + */ +void deactivate_file_page(struct page *page) +{ + /* + * In a workload with many unevictable page such as mprotect, + * unevictable page deactivation for accelerating reclaim is pointless. + */ + if (PageUnevictable(page)) + return; + + if (likely(get_page_unless_zero(page))) { + struct pagevec *pvec; + + local_lock(&lru_pvecs.lock); + pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate_file); + + if (!pagevec_add(pvec, page) || PageCompound(page)) + pagevec_lru_move_fn(pvec, lru_deactivate_file_fn, NULL); + local_unlock(&lru_pvecs.lock); + } +} + +/* + * deactivate_page - deactivate a page + * @page: page to deactivate + * + * deactivate_page() moves @page to the inactive list if @page was on the active + * list and was not an unevictable page. This is done to accelerate the reclaim + * of @page. + */ +void deactivate_page(struct page *page) +{ + if (PageLRU(page) && PageActive(page) && !PageUnevictable(page)) { + struct pagevec *pvec; + + local_lock(&lru_pvecs.lock); + pvec = this_cpu_ptr(&lru_pvecs.lru_deactivate); + get_page(page); + if (!pagevec_add(pvec, page) || PageCompound(page)) + pagevec_lru_move_fn(pvec, lru_deactivate_fn, NULL); + local_unlock(&lru_pvecs.lock); + } +} + +/** + * mark_page_lazyfree - make an anon page lazyfree + * @page: page to deactivate + * + * mark_page_lazyfree() moves @page to the inactive file list. + * This is done to accelerate the reclaim of @page. + */ +void mark_page_lazyfree(struct page *page) +{ + if (PageLRU(page) && PageAnon(page) && PageSwapBacked(page) && + !PageSwapCache(page) && !PageUnevictable(page)) { + struct pagevec *pvec; + + local_lock(&lru_pvecs.lock); + pvec = this_cpu_ptr(&lru_pvecs.lru_lazyfree); + get_page(page); + if (!pagevec_add(pvec, page) || PageCompound(page)) + pagevec_lru_move_fn(pvec, lru_lazyfree_fn, NULL); + local_unlock(&lru_pvecs.lock); + } +} + +void lru_add_drain(void) +{ + local_lock(&lru_pvecs.lock); + lru_add_drain_cpu(smp_processor_id()); + local_unlock(&lru_pvecs.lock); +} + +void lru_add_drain_cpu_zone(struct zone *zone) +{ + local_lock(&lru_pvecs.lock); + lru_add_drain_cpu(smp_processor_id()); + drain_local_pages(zone); + local_unlock(&lru_pvecs.lock); +} + +#ifdef CONFIG_SMP + +static DEFINE_PER_CPU(struct work_struct, lru_add_drain_work); + +static void lru_add_drain_per_cpu(struct work_struct *dummy) +{ + lru_add_drain(); +} + +/* + * Doesn't need any cpu hotplug locking because we do rely on per-cpu + * kworkers being shut down before our page_alloc_cpu_dead callback is + * executed on the offlined cpu. + * Calling this function with cpu hotplug locks held can actually lead + * to obscure indirect dependencies via WQ context. + */ +void lru_add_drain_all(void) +{ + /* + * lru_drain_gen - Global pages generation number + * + * (A) Definition: global lru_drain_gen = x implies that all generations + * 0 < n <= x are already *scheduled* for draining. + * + * This is an optimization for the highly-contended use case where a + * user space workload keeps constantly generating a flow of pages for + * each CPU. + */ + static unsigned int lru_drain_gen; + static struct cpumask has_work; + static DEFINE_MUTEX(lock); + unsigned cpu, this_gen; + + /* + * Make sure nobody triggers this path before mm_percpu_wq is fully + * initialized. + */ + if (WARN_ON(!mm_percpu_wq)) + return; + + /* + * Guarantee pagevec counter stores visible by this CPU are visible to + * other CPUs before loading the current drain generation. + */ + smp_mb(); + + /* + * (B) Locally cache global LRU draining generation number + * + * The read barrier ensures that the counter is loaded before the mutex + * is taken. It pairs with smp_mb() inside the mutex critical section + * at (D). + */ + this_gen = smp_load_acquire(&lru_drain_gen); + + mutex_lock(&lock); + + /* + * (C) Exit the draining operation if a newer generation, from another + * lru_add_drain_all(), was already scheduled for draining. Check (A). + */ + if (unlikely(this_gen != lru_drain_gen)) + goto done; + + /* + * (D) Increment global generation number + * + * Pairs with smp_load_acquire() at (B), outside of the critical + * section. Use a full memory barrier to guarantee that the new global + * drain generation number is stored before loading pagevec counters. + * + * This pairing must be done here, before the for_each_online_cpu loop + * below which drains the page vectors. + * + * Let x, y, and z represent some system CPU numbers, where x < y < z. + * Assume CPU #z is is in the middle of the for_each_online_cpu loop + * below and has already reached CPU #y's per-cpu data. CPU #x comes + * along, adds some pages to its per-cpu vectors, then calls + * lru_add_drain_all(). + * + * If the paired barrier is done at any later step, e.g. after the + * loop, CPU #x will just exit at (C) and miss flushing out all of its + * added pages. + */ + WRITE_ONCE(lru_drain_gen, lru_drain_gen + 1); + smp_mb(); + + cpumask_clear(&has_work); + for_each_online_cpu(cpu) { + struct work_struct *work = &per_cpu(lru_add_drain_work, cpu); + + if (pagevec_count(&per_cpu(lru_pvecs.lru_add, cpu)) || + data_race(pagevec_count(&per_cpu(lru_rotate.pvec, cpu))) || + pagevec_count(&per_cpu(lru_pvecs.lru_deactivate_file, cpu)) || + pagevec_count(&per_cpu(lru_pvecs.lru_deactivate, cpu)) || + pagevec_count(&per_cpu(lru_pvecs.lru_lazyfree, cpu)) || + need_activate_page_drain(cpu)) { + INIT_WORK(work, lru_add_drain_per_cpu); + queue_work_on(cpu, mm_percpu_wq, work); + __cpumask_set_cpu(cpu, &has_work); + } + } + + for_each_cpu(cpu, &has_work) + flush_work(&per_cpu(lru_add_drain_work, cpu)); + +done: + mutex_unlock(&lock); +} +#else +void lru_add_drain_all(void) +{ + lru_add_drain(); +} +#endif /* CONFIG_SMP */ + +/** + * release_pages - batched put_page() + * @pages: array of pages to release + * @nr: number of pages + * + * Decrement the reference count on all the pages in @pages. If it + * fell to zero, remove the page from the LRU and free it. + */ +void release_pages(struct page **pages, int nr) +{ + int i; + LIST_HEAD(pages_to_free); + struct pglist_data *locked_pgdat = NULL; + struct lruvec *lruvec; + unsigned long flags; + unsigned int lock_batch; + + for (i = 0; i < nr; i++) { + struct page *page = pages[i]; + + /* + * Make sure the IRQ-safe lock-holding time does not get + * excessive with a continuous string of pages from the + * same pgdat. The lock is held only if pgdat != NULL. + */ + if (locked_pgdat && ++lock_batch == SWAP_CLUSTER_MAX) { + spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags); + locked_pgdat = NULL; + } + + page = compound_head(page); + if (is_huge_zero_page(page)) + continue; + + if (is_zone_device_page(page)) { + if (locked_pgdat) { + spin_unlock_irqrestore(&locked_pgdat->lru_lock, + flags); + locked_pgdat = NULL; + } + /* + * ZONE_DEVICE pages that return 'false' from + * page_is_devmap_managed() do not require special + * processing, and instead, expect a call to + * put_page_testzero(). + */ + if (page_is_devmap_managed(page)) { + put_devmap_managed_page(page); + continue; + } + } + + if (!put_page_testzero(page)) + continue; + + if (PageCompound(page)) { + if (locked_pgdat) { + spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags); + locked_pgdat = NULL; + } + __put_compound_page(page); + continue; + } + + if (PageLRU(page)) { + struct pglist_data *pgdat = page_pgdat(page); + + if (pgdat != locked_pgdat) { + if (locked_pgdat) + spin_unlock_irqrestore(&locked_pgdat->lru_lock, + flags); + lock_batch = 0; + locked_pgdat = pgdat; + spin_lock_irqsave(&locked_pgdat->lru_lock, flags); + } + + lruvec = mem_cgroup_page_lruvec(page, locked_pgdat); + VM_BUG_ON_PAGE(!PageLRU(page), page); + __ClearPageLRU(page); + del_page_from_lru_list(page, lruvec, page_off_lru(page)); + } + + __ClearPageWaiters(page); + + list_add(&page->lru, &pages_to_free); + } + if (locked_pgdat) + spin_unlock_irqrestore(&locked_pgdat->lru_lock, flags); + + mem_cgroup_uncharge_list(&pages_to_free); + free_unref_page_list(&pages_to_free); +} +EXPORT_SYMBOL(release_pages); + +/* + * The pages which we're about to release may be in the deferred lru-addition + * queues. That would prevent them from really being freed right now. That's + * OK from a correctness point of view but is inefficient - those pages may be + * cache-warm and we want to give them back to the page allocator ASAP. + * + * So __pagevec_release() will drain those queues here. __pagevec_lru_add() + * and __pagevec_lru_add_active() call release_pages() directly to avoid + * mutual recursion. + */ +void __pagevec_release(struct pagevec *pvec) +{ + if (!pvec->percpu_pvec_drained) { + lru_add_drain(); + pvec->percpu_pvec_drained = true; + } + release_pages(pvec->pages, pagevec_count(pvec)); + pagevec_reinit(pvec); +} +EXPORT_SYMBOL(__pagevec_release); + +#ifdef CONFIG_TRANSPARENT_HUGEPAGE +/* used by __split_huge_page_refcount() */ +void lru_add_page_tail(struct page *page, struct page *page_tail, + struct lruvec *lruvec, struct list_head *list) +{ + VM_BUG_ON_PAGE(!PageHead(page), page); + VM_BUG_ON_PAGE(PageCompound(page_tail), page); + VM_BUG_ON_PAGE(PageLRU(page_tail), page); + lockdep_assert_held(&lruvec_pgdat(lruvec)->lru_lock); + + if (!list) + SetPageLRU(page_tail); + + if (likely(PageLRU(page))) + list_add_tail(&page_tail->lru, &page->lru); + else if (list) { + /* page reclaim is reclaiming a huge page */ + get_page(page_tail); + list_add_tail(&page_tail->lru, list); + } else { + /* + * Head page has not yet been counted, as an hpage, + * so we must account for each subpage individually. + * + * Put page_tail on the list at the correct position + * so they all end up in order. + */ + add_page_to_lru_list_tail(page_tail, lruvec, + page_lru(page_tail)); + } +} +#endif /* CONFIG_TRANSPARENT_HUGEPAGE */ + +static void __pagevec_lru_add_fn(struct page *page, struct lruvec *lruvec, + void *arg) +{ + enum lru_list lru; + int was_unevictable = TestClearPageUnevictable(page); + int nr_pages = thp_nr_pages(page); + + VM_BUG_ON_PAGE(PageLRU(page), page); + + /* + * Page becomes evictable in two ways: + * 1) Within LRU lock [munlock_vma_page() and __munlock_pagevec()]. + * 2) Before acquiring LRU lock to put the page to correct LRU and then + * a) do PageLRU check with lock [check_move_unevictable_pages] + * b) do PageLRU check before lock [clear_page_mlock] + * + * (1) & (2a) are ok as LRU lock will serialize them. For (2b), we need + * following strict ordering: + * + * #0: __pagevec_lru_add_fn #1: clear_page_mlock + * + * SetPageLRU() TestClearPageMlocked() + * smp_mb() // explicit ordering // above provides strict + * // ordering + * PageMlocked() PageLRU() + * + * + * if '#1' does not observe setting of PG_lru by '#0' and fails + * isolation, the explicit barrier will make sure that page_evictable + * check will put the page in correct LRU. Without smp_mb(), SetPageLRU + * can be reordered after PageMlocked check and can make '#1' to fail + * the isolation of the page whose Mlocked bit is cleared (#0 is also + * looking at the same page) and the evictable page will be stranded + * in an unevictable LRU. + */ + SetPageLRU(page); + smp_mb__after_atomic(); + + if (page_evictable(page)) { + lru = page_lru(page); + if (was_unevictable) + __count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages); + } else { + lru = LRU_UNEVICTABLE; + ClearPageActive(page); + SetPageUnevictable(page); + if (!was_unevictable) + __count_vm_events(UNEVICTABLE_PGCULLED, nr_pages); + } + + add_page_to_lru_list(page, lruvec, lru); + trace_mm_lru_insertion(page, lru); +} + +/* + * Add the passed pages to the LRU, then drop the caller's refcount + * on them. Reinitialises the caller's pagevec. + */ +void __pagevec_lru_add(struct pagevec *pvec) +{ + pagevec_lru_move_fn(pvec, __pagevec_lru_add_fn, NULL); +} + +/** + * pagevec_lookup_entries - gang pagecache lookup + * @pvec: Where the resulting entries are placed + * @mapping: The address_space to search + * @start: The starting entry index + * @nr_entries: The maximum number of pages + * @indices: The cache indices corresponding to the entries in @pvec + * + * pagevec_lookup_entries() will search for and return a group of up + * to @nr_pages pages and shadow entries in the mapping. All + * entries are placed in @pvec. pagevec_lookup_entries() takes a + * reference against actual pages in @pvec. + * + * The search returns a group of mapping-contiguous entries with + * ascending indexes. There may be holes in the indices due to + * not-present entries. + * + * Only one subpage of a Transparent Huge Page is returned in one call: + * allowing truncate_inode_pages_range() to evict the whole THP without + * cycling through a pagevec of extra references. + * + * pagevec_lookup_entries() returns the number of entries which were + * found. + */ +unsigned pagevec_lookup_entries(struct pagevec *pvec, + struct address_space *mapping, + pgoff_t start, unsigned nr_entries, + pgoff_t *indices) +{ + pvec->nr = find_get_entries(mapping, start, nr_entries, + pvec->pages, indices); + return pagevec_count(pvec); +} + +/** + * pagevec_remove_exceptionals - pagevec exceptionals pruning + * @pvec: The pagevec to prune + * + * pagevec_lookup_entries() fills both pages and exceptional radix + * tree entries into the pagevec. This function prunes all + * exceptionals from @pvec without leaving holes, so that it can be + * passed on to page-only pagevec operations. + */ +void pagevec_remove_exceptionals(struct pagevec *pvec) +{ + int i, j; + + for (i = 0, j = 0; i < pagevec_count(pvec); i++) { + struct page *page = pvec->pages[i]; + if (!xa_is_value(page)) + pvec->pages[j++] = page; + } + pvec->nr = j; +} + +/** + * pagevec_lookup_range - gang pagecache lookup + * @pvec: Where the resulting pages are placed + * @mapping: The address_space to search + * @start: The starting page index + * @end: The final page index + * + * pagevec_lookup_range() will search for & return a group of up to PAGEVEC_SIZE + * pages in the mapping starting from index @start and upto index @end + * (inclusive). The pages are placed in @pvec. pagevec_lookup() takes a + * reference against the pages in @pvec. + * + * The search returns a group of mapping-contiguous pages with ascending + * indexes. There may be holes in the indices due to not-present pages. We + * also update @start to index the next page for the traversal. + * + * pagevec_lookup_range() returns the number of pages which were found. If this + * number is smaller than PAGEVEC_SIZE, the end of specified range has been + * reached. + */ +unsigned pagevec_lookup_range(struct pagevec *pvec, + struct address_space *mapping, pgoff_t *start, pgoff_t end) +{ + pvec->nr = find_get_pages_range(mapping, start, end, PAGEVEC_SIZE, + pvec->pages); + return pagevec_count(pvec); +} +EXPORT_SYMBOL(pagevec_lookup_range); + +unsigned pagevec_lookup_range_tag(struct pagevec *pvec, + struct address_space *mapping, pgoff_t *index, pgoff_t end, + xa_mark_t tag) +{ + pvec->nr = find_get_pages_range_tag(mapping, index, end, tag, + PAGEVEC_SIZE, pvec->pages); + return pagevec_count(pvec); +} +EXPORT_SYMBOL(pagevec_lookup_range_tag); + +unsigned pagevec_lookup_range_nr_tag(struct pagevec *pvec, + struct address_space *mapping, pgoff_t *index, pgoff_t end, + xa_mark_t tag, unsigned max_pages) +{ + pvec->nr = find_get_pages_range_tag(mapping, index, end, tag, + min_t(unsigned int, max_pages, PAGEVEC_SIZE), pvec->pages); + return pagevec_count(pvec); +} +EXPORT_SYMBOL(pagevec_lookup_range_nr_tag); +/* + * Perform any setup for the swap system + */ +void __init swap_setup(void) +{ + unsigned long megs = totalram_pages() >> (20 - PAGE_SHIFT); + + /* Use a smaller cluster for small-memory machines */ + if (megs < 16) + page_cluster = 2; + else + page_cluster = 3; + /* + * Right now other parts of the system means that we + * _really_ don't want to cluster much more + */ +} + +#ifdef CONFIG_DEV_PAGEMAP_OPS +void put_devmap_managed_page(struct page *page) +{ + int count; + + if (WARN_ON_ONCE(!page_is_devmap_managed(page))) + return; + + count = page_ref_dec_return(page); + + /* + * devmap page refcounts are 1-based, rather than 0-based: if + * refcount is 1, then the page is free and the refcount is + * stable because nobody holds a reference on the page. + */ + if (count == 1) + free_devmap_managed_page(page); + else if (!count) + __put_page(page); +} +EXPORT_SYMBOL(put_devmap_managed_page); +#endif |