| // 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 <linux/buffer_head.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.fbatch which requires disabling interrupts */ |
| struct lru_rotate { |
| local_lock_t lock; |
| struct folio_batch fbatch; |
| }; |
| static DEFINE_PER_CPU(struct lru_rotate, lru_rotate) = { |
| .lock = INIT_LOCAL_LOCK(lock), |
| }; |
| |
| /* |
| * The following folio batches are grouped together because they are protected |
| * by disabling preemption (and interrupts remain enabled). |
| */ |
| struct cpu_fbatches { |
| local_lock_t lock; |
| struct folio_batch lru_add; |
| struct folio_batch lru_deactivate_file; |
| struct folio_batch lru_deactivate; |
| struct folio_batch lru_lazyfree; |
| #ifdef CONFIG_SMP |
| struct folio_batch activate; |
| #endif |
| }; |
| static DEFINE_PER_CPU(struct cpu_fbatches, cpu_fbatches) = { |
| .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 - and for compound pages. |
| */ |
| static void __page_cache_release(struct folio *folio) |
| { |
| if (folio_test_lru(folio)) { |
| struct lruvec *lruvec; |
| unsigned long flags; |
| |
| lruvec = folio_lruvec_lock_irqsave(folio, &flags); |
| lruvec_del_folio(lruvec, folio); |
| __folio_clear_lru_flags(folio); |
| unlock_page_lruvec_irqrestore(lruvec, flags); |
| } |
| /* See comment on folio_test_mlocked in release_pages() */ |
| if (unlikely(folio_test_mlocked(folio))) { |
| long nr_pages = folio_nr_pages(folio); |
| |
| __folio_clear_mlocked(folio); |
| zone_stat_mod_folio(folio, NR_MLOCK, -nr_pages); |
| count_vm_events(UNEVICTABLE_PGCLEARED, nr_pages); |
| } |
| } |
| |
| static void __folio_put_small(struct folio *folio) |
| { |
| __page_cache_release(folio); |
| mem_cgroup_uncharge(folio); |
| free_unref_page(&folio->page, 0); |
| } |
| |
| static void __folio_put_large(struct folio *folio) |
| { |
| /* |
| * __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 (!folio_test_hugetlb(folio)) |
| __page_cache_release(folio); |
| destroy_large_folio(folio); |
| } |
| |
| void __folio_put(struct folio *folio) |
| { |
| if (unlikely(folio_is_zone_device(folio))) |
| free_zone_device_page(&folio->page); |
| else if (unlikely(folio_test_large(folio))) |
| __folio_put_large(folio); |
| else |
| __folio_put_small(folio); |
| } |
| EXPORT_SYMBOL(__folio_put); |
| |
| /** |
| * 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. |
| */ |
| void put_pages_list(struct list_head *pages) |
| { |
| struct folio *folio, *next; |
| |
| list_for_each_entry_safe(folio, next, pages, lru) { |
| if (!folio_put_testzero(folio)) { |
| list_del(&folio->lru); |
| continue; |
| } |
| if (folio_test_large(folio)) { |
| list_del(&folio->lru); |
| __folio_put_large(folio); |
| continue; |
| } |
| /* LRU flag must be clear because it's passed using the lru */ |
| } |
| |
| free_unref_page_list(pages); |
| INIT_LIST_HEAD(pages); |
| } |
| 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_segs is 0 or negative, returns 0. If no pages were pinned, returns 0. |
| * 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); |
| |
| typedef void (*move_fn_t)(struct lruvec *lruvec, struct folio *folio); |
| |
| static void lru_add_fn(struct lruvec *lruvec, struct folio *folio) |
| { |
| int was_unevictable = folio_test_clear_unevictable(folio); |
| long nr_pages = folio_nr_pages(folio); |
| |
| VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); |
| |
| /* |
| * Is an smp_mb__after_atomic() still required here, before |
| * folio_evictable() tests the mlocked flag, to rule out the possibility |
| * of stranding an evictable folio on an unevictable LRU? I think |
| * not, because __munlock_page() only clears the mlocked flag |
| * while the LRU lock is held. |
| * |
| * (That is not true of __page_cache_release(), and not necessarily |
| * true of release_pages(): but those only clear the mlocked flag after |
| * folio_put_testzero() has excluded any other users of the folio.) |
| */ |
| if (folio_evictable(folio)) { |
| if (was_unevictable) |
| __count_vm_events(UNEVICTABLE_PGRESCUED, nr_pages); |
| } else { |
| folio_clear_active(folio); |
| folio_set_unevictable(folio); |
| /* |
| * folio->mlock_count = !!folio_test_mlocked(folio)? |
| * But that leaves __mlock_page() in doubt whether another |
| * actor has already counted the mlock or not. Err on the |
| * safe side, underestimate, let page reclaim fix it, rather |
| * than leaving a page on the unevictable LRU indefinitely. |
| */ |
| folio->mlock_count = 0; |
| if (!was_unevictable) |
| __count_vm_events(UNEVICTABLE_PGCULLED, nr_pages); |
| } |
| |
| lruvec_add_folio(lruvec, folio); |
| trace_mm_lru_insertion(folio); |
| } |
| |
| static void folio_batch_move_lru(struct folio_batch *fbatch, move_fn_t move_fn) |
| { |
| int i; |
| struct lruvec *lruvec = NULL; |
| unsigned long flags = 0; |
| |
| for (i = 0; i < folio_batch_count(fbatch); i++) { |
| struct folio *folio = fbatch->folios[i]; |
| |
| /* block memcg migration while the folio moves between lru */ |
| if (move_fn != lru_add_fn && !folio_test_clear_lru(folio)) |
| continue; |
| |
| lruvec = folio_lruvec_relock_irqsave(folio, lruvec, &flags); |
| move_fn(lruvec, folio); |
| |
| folio_set_lru(folio); |
| } |
| |
| if (lruvec) |
| unlock_page_lruvec_irqrestore(lruvec, flags); |
| folios_put(fbatch->folios, folio_batch_count(fbatch)); |
| folio_batch_init(fbatch); |
| } |
| |
| static void folio_batch_add_and_move(struct folio_batch *fbatch, |
| struct folio *folio, move_fn_t move_fn) |
| { |
| if (folio_batch_add(fbatch, folio) && !folio_test_large(folio) && |
| !lru_cache_disabled()) |
| return; |
| folio_batch_move_lru(fbatch, move_fn); |
| } |
| |
| static void lru_move_tail_fn(struct lruvec *lruvec, struct folio *folio) |
| { |
| if (!folio_test_unevictable(folio)) { |
| lruvec_del_folio(lruvec, folio); |
| folio_clear_active(folio); |
| lruvec_add_folio_tail(lruvec, folio); |
| __count_vm_events(PGROTATED, folio_nr_pages(folio)); |
| } |
| } |
| |
| /* |
| * Writeback is about to end against a folio which has been marked for |
| * immediate reclaim. If it still appears to be reclaimable, move it |
| * to the tail of the inactive list. |
| * |
| * folio_rotate_reclaimable() must disable IRQs, to prevent nasty races. |
| */ |
| void folio_rotate_reclaimable(struct folio *folio) |
| { |
| if (!folio_test_locked(folio) && !folio_test_dirty(folio) && |
| !folio_test_unevictable(folio) && folio_test_lru(folio)) { |
| struct folio_batch *fbatch; |
| unsigned long flags; |
| |
| folio_get(folio); |
| local_lock_irqsave(&lru_rotate.lock, flags); |
| fbatch = this_cpu_ptr(&lru_rotate.fbatch); |
| folio_batch_add_and_move(fbatch, folio, lru_move_tail_fn); |
| local_unlock_irqrestore(&lru_rotate.lock, flags); |
| } |
| } |
| |
| void lru_note_cost(struct lruvec *lruvec, bool file, unsigned int nr_pages) |
| { |
| do { |
| unsigned long lrusize; |
| |
| /* |
| * Hold lruvec->lru_lock is safe here, since |
| * 1) The pinned lruvec in reclaim, or |
| * 2) From a pre-LRU page during refault (which also holds the |
| * rcu lock, so would be safe even if the page was on the LRU |
| * and could move simultaneously to a new lruvec). |
| */ |
| spin_lock_irq(&lruvec->lru_lock); |
| /* 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; |
| } |
| spin_unlock_irq(&lruvec->lru_lock); |
| } while ((lruvec = parent_lruvec(lruvec))); |
| } |
| |
| void lru_note_cost_folio(struct folio *folio) |
| { |
| lru_note_cost(folio_lruvec(folio), folio_is_file_lru(folio), |
| folio_nr_pages(folio)); |
| } |
| |
| static void folio_activate_fn(struct lruvec *lruvec, struct folio *folio) |
| { |
| if (!folio_test_active(folio) && !folio_test_unevictable(folio)) { |
| long nr_pages = folio_nr_pages(folio); |
| |
| lruvec_del_folio(lruvec, folio); |
| folio_set_active(folio); |
| lruvec_add_folio(lruvec, folio); |
| trace_mm_lru_activate(folio); |
| |
| __count_vm_events(PGACTIVATE, nr_pages); |
| __count_memcg_events(lruvec_memcg(lruvec), PGACTIVATE, |
| nr_pages); |
| } |
| } |
| |
| #ifdef CONFIG_SMP |
| static void folio_activate_drain(int cpu) |
| { |
| struct folio_batch *fbatch = &per_cpu(cpu_fbatches.activate, cpu); |
| |
| if (folio_batch_count(fbatch)) |
| folio_batch_move_lru(fbatch, folio_activate_fn); |
| } |
| |
| void folio_activate(struct folio *folio) |
| { |
| if (folio_test_lru(folio) && !folio_test_active(folio) && |
| !folio_test_unevictable(folio)) { |
| struct folio_batch *fbatch; |
| |
| folio_get(folio); |
| local_lock(&cpu_fbatches.lock); |
| fbatch = this_cpu_ptr(&cpu_fbatches.activate); |
| folio_batch_add_and_move(fbatch, folio, folio_activate_fn); |
| local_unlock(&cpu_fbatches.lock); |
| } |
| } |
| |
| #else |
| static inline void folio_activate_drain(int cpu) |
| { |
| } |
| |
| void folio_activate(struct folio *folio) |
| { |
| struct lruvec *lruvec; |
| |
| if (folio_test_clear_lru(folio)) { |
| lruvec = folio_lruvec_lock_irq(folio); |
| folio_activate_fn(lruvec, folio); |
| unlock_page_lruvec_irq(lruvec); |
| folio_set_lru(folio); |
| } |
| } |
| #endif |
| |
| static void __lru_cache_activate_folio(struct folio *folio) |
| { |
| struct folio_batch *fbatch; |
| int i; |
| |
| local_lock(&cpu_fbatches.lock); |
| fbatch = this_cpu_ptr(&cpu_fbatches.lru_add); |
| |
| /* |
| * Search backwards on the optimistic assumption that the folio being |
| * activated has just been added to this batch. Note that only |
| * the local batch is examined as a !LRU folio could be in the |
| * process of being released, reclaimed, migrated or on a remote |
| * batch that is currently being drained. Furthermore, marking |
| * a remote batch's folio active potentially hits a race where |
| * a folio is marked active just after it is added to the inactive |
| * list causing accounting errors and BUG_ON checks to trigger. |
| */ |
| for (i = folio_batch_count(fbatch) - 1; i >= 0; i--) { |
| struct folio *batch_folio = fbatch->folios[i]; |
| |
| if (batch_folio == folio) { |
| folio_set_active(folio); |
| break; |
| } |
| } |
| |
| local_unlock(&cpu_fbatches.lock); |
| } |
| |
| #ifdef CONFIG_LRU_GEN |
| static void folio_inc_refs(struct folio *folio) |
| { |
| unsigned long new_flags, old_flags = READ_ONCE(folio->flags); |
| |
| if (folio_test_unevictable(folio)) |
| return; |
| |
| if (!folio_test_referenced(folio)) { |
| folio_set_referenced(folio); |
| return; |
| } |
| |
| if (!folio_test_workingset(folio)) { |
| folio_set_workingset(folio); |
| return; |
| } |
| |
| /* see the comment on MAX_NR_TIERS */ |
| do { |
| new_flags = old_flags & LRU_REFS_MASK; |
| if (new_flags == LRU_REFS_MASK) |
| break; |
| |
| new_flags += BIT(LRU_REFS_PGOFF); |
| new_flags |= old_flags & ~LRU_REFS_MASK; |
| } while (!try_cmpxchg(&folio->flags, &old_flags, new_flags)); |
| } |
| #else |
| static void folio_inc_refs(struct folio *folio) |
| { |
| } |
| #endif /* CONFIG_LRU_GEN */ |
| |
| /* |
| * 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 folio_mark_accessed(struct folio *folio) |
| { |
| if (lru_gen_enabled()) { |
| folio_inc_refs(folio); |
| return; |
| } |
| |
| if (!folio_test_referenced(folio)) { |
| folio_set_referenced(folio); |
| } else if (folio_test_unevictable(folio)) { |
| /* |
| * Unevictable pages are on the "LRU_UNEVICTABLE" list. But, |
| * this list is never rotated or maintained, so marking an |
| * unevictable page accessed has no effect. |
| */ |
| } else if (!folio_test_active(folio)) { |
| /* |
| * If the folio is on the LRU, queue it for activation via |
| * cpu_fbatches.activate. Otherwise, assume the folio is in a |
| * folio_batch, mark it active and it'll be moved to the active |
| * LRU on the next drain. |
| */ |
| if (folio_test_lru(folio)) |
| folio_activate(folio); |
| else |
| __lru_cache_activate_folio(folio); |
| folio_clear_referenced(folio); |
| workingset_activation(folio); |
| } |
| if (folio_test_idle(folio)) |
| folio_clear_idle(folio); |
| } |
| EXPORT_SYMBOL(folio_mark_accessed); |
| |
| /** |
| * folio_add_lru - Add a folio to an LRU list. |
| * @folio: The folio to be added to the LRU. |
| * |
| * Queue the folio for addition to the LRU. The decision on whether |
| * to add the page to the [in]active [file|anon] list is deferred until the |
| * folio_batch is drained. This gives a chance for the caller of folio_add_lru() |
| * have the folio added to the active list using folio_mark_accessed(). |
| */ |
| void folio_add_lru(struct folio *folio) |
| { |
| struct folio_batch *fbatch; |
| |
| VM_BUG_ON_FOLIO(folio_test_active(folio) && |
| folio_test_unevictable(folio), folio); |
| VM_BUG_ON_FOLIO(folio_test_lru(folio), folio); |
| |
| /* see the comment in lru_gen_add_folio() */ |
| if (lru_gen_enabled() && !folio_test_unevictable(folio) && |
| lru_gen_in_fault() && !(current->flags & PF_MEMALLOC)) |
| folio_set_active(folio); |
| |
| folio_get(folio); |
| local_lock(&cpu_fbatches.lock); |
| fbatch = this_cpu_ptr(&cpu_fbatches.lru_add); |
| folio_batch_add_and_move(fbatch, folio, lru_add_fn); |
| local_unlock(&cpu_fbatches.lock); |
| } |
| EXPORT_SYMBOL(folio_add_lru); |
| |
| /** |
| * 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) |
| { |
| VM_BUG_ON_PAGE(PageLRU(page), page); |
| |
| if (unlikely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) == VM_LOCKED)) |
| mlock_new_page(page); |
| else |
| lru_cache_add(page); |
| } |
| |
| /* |
| * If the folio cannot 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 folio isn't mapped and dirty/writeback, the folio |
| * could be reclaimed asap using the reclaim flag. |
| * |
| * 1. active, mapped folio -> none |
| * 2. active, dirty/writeback folio -> inactive, head, reclaim |
| * 3. inactive, mapped folio -> none |
| * 4. inactive, dirty/writeback folio -> inactive, head, reclaim |
| * 5. inactive, clean -> inactive, tail |
| * 6. Others -> none |
| * |
| * In 4, it moves to the head of the inactive list so the folio is |
| * written out by flusher threads as this is much more efficient |
| * than the single-page writeout from reclaim. |
| */ |
| static void lru_deactivate_file_fn(struct lruvec *lruvec, struct folio *folio) |
| { |
| bool active = folio_test_active(folio); |
| long nr_pages = folio_nr_pages(folio); |
| |
| if (folio_test_unevictable(folio)) |
| return; |
| |
| /* Some processes are using the folio */ |
| if (folio_mapped(folio)) |
| return; |
| |
| lruvec_del_folio(lruvec, folio); |
| folio_clear_active(folio); |
| folio_clear_referenced(folio); |
| |
| if (folio_test_writeback(folio) || folio_test_dirty(folio)) { |
| /* |
| * Setting the reclaim flag could race with |
| * folio_end_writeback() and confuse readahead. But the |
| * race window is _really_ small and it's not a critical |
| * problem. |
| */ |
| lruvec_add_folio(lruvec, folio); |
| folio_set_reclaim(folio); |
| } else { |
| /* |
| * The folio's writeback ended while it was in the batch. |
| * We move that folio to the tail of the inactive list. |
| */ |
| lruvec_add_folio_tail(lruvec, folio); |
| __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 lruvec *lruvec, struct folio *folio) |
| { |
| if (!folio_test_unevictable(folio) && (folio_test_active(folio) || lru_gen_enabled())) { |
| long nr_pages = folio_nr_pages(folio); |
| |
| lruvec_del_folio(lruvec, folio); |
| folio_clear_active(folio); |
| folio_clear_referenced(folio); |
| lruvec_add_folio(lruvec, folio); |
| |
| __count_vm_events(PGDEACTIVATE, nr_pages); |
| __count_memcg_events(lruvec_memcg(lruvec), PGDEACTIVATE, |
| nr_pages); |
| } |
| } |
| |
| static void lru_lazyfree_fn(struct lruvec *lruvec, struct folio *folio) |
| { |
| if (folio_test_anon(folio) && folio_test_swapbacked(folio) && |
| !folio_test_swapcache(folio) && !folio_test_unevictable(folio)) { |
| long nr_pages = folio_nr_pages(folio); |
| |
| lruvec_del_folio(lruvec, folio); |
| folio_clear_active(folio); |
| folio_clear_referenced(folio); |
| /* |
| * Lazyfree folios are clean anonymous folios. They have |
| * the swapbacked flag cleared, to distinguish them from normal |
| * anonymous folios |
| */ |
| folio_clear_swapbacked(folio); |
| lruvec_add_folio(lruvec, folio); |
| |
| __count_vm_events(PGLAZYFREE, nr_pages); |
| __count_memcg_events(lruvec_memcg(lruvec), PGLAZYFREE, |
| nr_pages); |
| } |
| } |
| |
| /* |
| * Drain pages out of the cpu's folio_batch. |
| * 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 cpu_fbatches *fbatches = &per_cpu(cpu_fbatches, cpu); |
| struct folio_batch *fbatch = &fbatches->lru_add; |
| |
| if (folio_batch_count(fbatch)) |
| folio_batch_move_lru(fbatch, lru_add_fn); |
| |
| fbatch = &per_cpu(lru_rotate.fbatch, cpu); |
| /* Disabling interrupts below acts as a compiler barrier. */ |
| if (data_race(folio_batch_count(fbatch))) { |
| unsigned long flags; |
| |
| /* No harm done if a racing interrupt already did this */ |
| local_lock_irqsave(&lru_rotate.lock, flags); |
| folio_batch_move_lru(fbatch, lru_move_tail_fn); |
| local_unlock_irqrestore(&lru_rotate.lock, flags); |
| } |
| |
| fbatch = &fbatches->lru_deactivate_file; |
| if (folio_batch_count(fbatch)) |
| folio_batch_move_lru(fbatch, lru_deactivate_file_fn); |
| |
| fbatch = &fbatches->lru_deactivate; |
| if (folio_batch_count(fbatch)) |
| folio_batch_move_lru(fbatch, lru_deactivate_fn); |
| |
| fbatch = &fbatches->lru_lazyfree; |
| if (folio_batch_count(fbatch)) |
| folio_batch_move_lru(fbatch, lru_lazyfree_fn); |
| |
| folio_activate_drain(cpu); |
| } |
| |
| /** |
| * deactivate_file_folio() - Deactivate a file folio. |
| * @folio: Folio to deactivate. |
| * |
| * This function hints to the VM that @folio is a good reclaim candidate, |
| * for example if its invalidation fails due to the folio being dirty |
| * or under writeback. |
| * |
| * Context: Caller holds a reference on the folio. |
| */ |
| void deactivate_file_folio(struct folio *folio) |
| { |
| struct folio_batch *fbatch; |
| |
| /* Deactivating an unevictable folio will not accelerate reclaim */ |
| if (folio_test_unevictable(folio)) |
| return; |
| |
| folio_get(folio); |
| local_lock(&cpu_fbatches.lock); |
| fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate_file); |
| folio_batch_add_and_move(fbatch, folio, lru_deactivate_file_fn); |
| local_unlock(&cpu_fbatches.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) |
| { |
| struct folio *folio = page_folio(page); |
| |
| if (folio_test_lru(folio) && !folio_test_unevictable(folio) && |
| (folio_test_active(folio) || lru_gen_enabled())) { |
| struct folio_batch *fbatch; |
| |
| folio_get(folio); |
| local_lock(&cpu_fbatches.lock); |
| fbatch = this_cpu_ptr(&cpu_fbatches.lru_deactivate); |
| folio_batch_add_and_move(fbatch, folio, lru_deactivate_fn); |
| local_unlock(&cpu_fbatches.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) |
| { |
| struct folio *folio = page_folio(page); |
| |
| if (folio_test_lru(folio) && folio_test_anon(folio) && |
| folio_test_swapbacked(folio) && !folio_test_swapcache(folio) && |
| !folio_test_unevictable(folio)) { |
| struct folio_batch *fbatch; |
| |
| folio_get(folio); |
| local_lock(&cpu_fbatches.lock); |
| fbatch = this_cpu_ptr(&cpu_fbatches.lru_lazyfree); |
| folio_batch_add_and_move(fbatch, folio, lru_lazyfree_fn); |
| local_unlock(&cpu_fbatches.lock); |
| } |
| } |
| |
| void lru_add_drain(void) |
| { |
| local_lock(&cpu_fbatches.lock); |
| lru_add_drain_cpu(smp_processor_id()); |
| local_unlock(&cpu_fbatches.lock); |
| mlock_page_drain_local(); |
| } |
| |
| /* |
| * It's called from per-cpu workqueue context in SMP case so |
| * lru_add_drain_cpu and invalidate_bh_lrus_cpu should run on |
| * the same cpu. It shouldn't be a problem in !SMP case since |
| * the core is only one and the locks will disable preemption. |
| */ |
| static void lru_add_and_bh_lrus_drain(void) |
| { |
| local_lock(&cpu_fbatches.lock); |
| lru_add_drain_cpu(smp_processor_id()); |
| local_unlock(&cpu_fbatches.lock); |
| invalidate_bh_lrus_cpu(); |
| mlock_page_drain_local(); |
| } |
| |
| void lru_add_drain_cpu_zone(struct zone *zone) |
| { |
| local_lock(&cpu_fbatches.lock); |
| lru_add_drain_cpu(smp_processor_id()); |
| drain_local_pages(zone); |
| local_unlock(&cpu_fbatches.lock); |
| mlock_page_drain_local(); |
| } |
| |
| #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_and_bh_lrus_drain(); |
| } |
| |
| static bool cpu_needs_drain(unsigned int cpu) |
| { |
| struct cpu_fbatches *fbatches = &per_cpu(cpu_fbatches, cpu); |
| |
| /* Check these in order of likelihood that they're not zero */ |
| return folio_batch_count(&fbatches->lru_add) || |
| data_race(folio_batch_count(&per_cpu(lru_rotate.fbatch, cpu))) || |
| folio_batch_count(&fbatches->lru_deactivate_file) || |
| folio_batch_count(&fbatches->lru_deactivate) || |
| folio_batch_count(&fbatches->lru_lazyfree) || |
| folio_batch_count(&fbatches->activate) || |
| need_mlock_page_drain(cpu) || |
| has_bh_in_lru(cpu, NULL); |
| } |
| |
| /* |
| * 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. |
| */ |
| static inline void __lru_add_drain_all(bool force_all_cpus) |
| { |
| /* |
| * 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 folio_batch 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 && !force_all_cpus)) |
| 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 |
| * folio_batch 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 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 (cpu_needs_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); |
| } |
| |
| void lru_add_drain_all(void) |
| { |
| __lru_add_drain_all(false); |
| } |
| #else |
| void lru_add_drain_all(void) |
| { |
| lru_add_drain(); |
| } |
| #endif /* CONFIG_SMP */ |
| |
| atomic_t lru_disable_count = ATOMIC_INIT(0); |
| |
| /* |
| * lru_cache_disable() needs to be called before we start compiling |
| * a list of pages to be migrated using isolate_lru_page(). |
| * It drains pages on LRU cache and then disable on all cpus until |
| * lru_cache_enable is called. |
| * |
| * Must be paired with a call to lru_cache_enable(). |
| */ |
| void lru_cache_disable(void) |
| { |
| atomic_inc(&lru_disable_count); |
| /* |
| * Readers of lru_disable_count are protected by either disabling |
| * preemption or rcu_read_lock: |
| * |
| * preempt_disable, local_irq_disable [bh_lru_lock()] |
| * rcu_read_lock [rt_spin_lock CONFIG_PREEMPT_RT] |
| * preempt_disable [local_lock !CONFIG_PREEMPT_RT] |
| * |
| * Since v5.1 kernel, synchronize_rcu() is guaranteed to wait on |
| * preempt_disable() regions of code. So any CPU which sees |
| * lru_disable_count = 0 will have exited the critical |
| * section when synchronize_rcu() returns. |
| */ |
| synchronize_rcu_expedited(); |
| #ifdef CONFIG_SMP |
| __lru_add_drain_all(true); |
| #else |
| lru_add_and_bh_lrus_drain(); |
| #endif |
| } |
| |
| /** |
| * release_pages - batched put_page() |
| * @pages: array of pages to release |
| * @nr: number of pages |
| * |
| * Decrement the reference count on all the pages in @pages. If it |
| * fell to zero, remove the page from the LRU and free it. |
| */ |
| void release_pages(struct page **pages, int nr) |
| { |
| int i; |
| LIST_HEAD(pages_to_free); |
| struct lruvec *lruvec = NULL; |
| unsigned long flags = 0; |
| unsigned int lock_batch; |
| |
| for (i = 0; i < nr; i++) { |
| struct folio *folio = page_folio(pages[i]); |
| |
| /* |
| * Make sure the IRQ-safe lock-holding time does not get |
| * excessive with a continuous string of pages from the |
| * same lruvec. The lock is held only if lruvec != NULL. |
| */ |
| if (lruvec && ++lock_batch == SWAP_CLUSTER_MAX) { |
| unlock_page_lruvec_irqrestore(lruvec, flags); |
| lruvec = NULL; |
| } |
| |
| if (is_huge_zero_page(&folio->page)) |
| continue; |
| |
| if (folio_is_zone_device(folio)) { |
| if (lruvec) { |
| unlock_page_lruvec_irqrestore(lruvec, flags); |
| lruvec = NULL; |
| } |
| if (put_devmap_managed_page(&folio->page)) |
| continue; |
| if (folio_put_testzero(folio)) |
| free_zone_device_page(&folio->page); |
| continue; |
| } |
| |
| if (!folio_put_testzero(folio)) |
| continue; |
| |
| if (folio_test_large(folio)) { |
| if (lruvec) { |
| unlock_page_lruvec_irqrestore(lruvec, flags); |
| lruvec = NULL; |
| } |
| __folio_put_large(folio); |
| continue; |
| } |
| |
| if (folio_test_lru(folio)) { |
| struct lruvec *prev_lruvec = lruvec; |
| |
| lruvec = folio_lruvec_relock_irqsave(folio, lruvec, |
| &flags); |
| if (prev_lruvec != lruvec) |
| lock_batch = 0; |
| |
| lruvec_del_folio(lruvec, folio); |
| __folio_clear_lru_flags(folio); |
| } |
| |
| /* |
| * In rare cases, when truncation or holepunching raced with |
| * munlock after VM_LOCKED was cleared, Mlocked may still be |
| * found set here. This does not indicate a problem, unless |
| * "unevictable_pgs_cleared" appears worryingly large. |
| */ |
| if (unlikely(folio_test_mlocked(folio))) { |
| __folio_clear_mlocked(folio); |
| zone_stat_sub_folio(folio, NR_MLOCK); |
| count_vm_event(UNEVICTABLE_PGCLEARED); |
| } |
| |
| list_add(&folio->lru, &pages_to_free); |
| } |
| if (lruvec) |
| unlock_page_lruvec_irqrestore(lruvec, 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. |
| * folio_batch_move_lru() calls folios_put() 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); |
| |
| /** |
| * folio_batch_remove_exceptionals() - Prune non-folios from a batch. |
| * @fbatch: The batch to prune |
| * |
| * find_get_entries() fills a batch with both folios and shadow/swap/DAX |
| * entries. This function prunes all the non-folio entries from @fbatch |
| * without leaving holes, so that it can be passed on to folio-only batch |
| * operations. |
| */ |
| void folio_batch_remove_exceptionals(struct folio_batch *fbatch) |
| { |
| unsigned int i, j; |
| |
| for (i = 0, j = 0; i < folio_batch_count(fbatch); i++) { |
| struct folio *folio = fbatch->folios[i]; |
| if (!xa_is_value(folio)) |
| fbatch->folios[j++] = folio; |
| } |
| fbatch->nr = j; |
| } |
| |
| 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); |
| |
| /* |
| * 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 |
| */ |
| } |