| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * linux/mm/swapfile.c |
| * |
| * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
| * Swap reorganised 29.12.95, Stephen Tweedie |
| */ |
| |
| #include <linux/blkdev.h> |
| #include <linux/mm.h> |
| #include <linux/sched/mm.h> |
| #include <linux/sched/task.h> |
| #include <linux/hugetlb.h> |
| #include <linux/mman.h> |
| #include <linux/slab.h> |
| #include <linux/kernel_stat.h> |
| #include <linux/swap.h> |
| #include <linux/vmalloc.h> |
| #include <linux/pagemap.h> |
| #include <linux/namei.h> |
| #include <linux/shmem_fs.h> |
| #include <linux/blk-cgroup.h> |
| #include <linux/random.h> |
| #include <linux/writeback.h> |
| #include <linux/proc_fs.h> |
| #include <linux/seq_file.h> |
| #include <linux/init.h> |
| #include <linux/ksm.h> |
| #include <linux/rmap.h> |
| #include <linux/security.h> |
| #include <linux/backing-dev.h> |
| #include <linux/mutex.h> |
| #include <linux/capability.h> |
| #include <linux/syscalls.h> |
| #include <linux/memcontrol.h> |
| #include <linux/poll.h> |
| #include <linux/oom.h> |
| #include <linux/swapfile.h> |
| #include <linux/export.h> |
| #include <linux/swap_slots.h> |
| #include <linux/sort.h> |
| #include <linux/completion.h> |
| #include <linux/suspend.h> |
| #include <linux/zswap.h> |
| #include <linux/plist.h> |
| |
| #include <asm/tlbflush.h> |
| #include <linux/swapops.h> |
| #include <linux/swap_cgroup.h> |
| #include "internal.h" |
| #include "swap.h" |
| |
| static bool swap_count_continued(struct swap_info_struct *, pgoff_t, |
| unsigned char); |
| static void free_swap_count_continuations(struct swap_info_struct *); |
| static void swap_entry_range_free(struct swap_info_struct *si, swp_entry_t entry, |
| unsigned int nr_pages); |
| static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, |
| unsigned int nr_entries); |
| static bool folio_swapcache_freeable(struct folio *folio); |
| static struct swap_cluster_info *lock_cluster_or_swap_info( |
| struct swap_info_struct *si, unsigned long offset); |
| static void unlock_cluster_or_swap_info(struct swap_info_struct *si, |
| struct swap_cluster_info *ci); |
| |
| static DEFINE_SPINLOCK(swap_lock); |
| static unsigned int nr_swapfiles; |
| atomic_long_t nr_swap_pages; |
| /* |
| * Some modules use swappable objects and may try to swap them out under |
| * memory pressure (via the shrinker). Before doing so, they may wish to |
| * check to see if any swap space is available. |
| */ |
| EXPORT_SYMBOL_GPL(nr_swap_pages); |
| /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */ |
| long total_swap_pages; |
| static int least_priority = -1; |
| unsigned long swapfile_maximum_size; |
| #ifdef CONFIG_MIGRATION |
| bool swap_migration_ad_supported; |
| #endif /* CONFIG_MIGRATION */ |
| |
| static const char Bad_file[] = "Bad swap file entry "; |
| static const char Unused_file[] = "Unused swap file entry "; |
| static const char Bad_offset[] = "Bad swap offset entry "; |
| static const char Unused_offset[] = "Unused swap offset entry "; |
| |
| /* |
| * all active swap_info_structs |
| * protected with swap_lock, and ordered by priority. |
| */ |
| static PLIST_HEAD(swap_active_head); |
| |
| /* |
| * all available (active, not full) swap_info_structs |
| * protected with swap_avail_lock, ordered by priority. |
| * This is used by folio_alloc_swap() instead of swap_active_head |
| * because swap_active_head includes all swap_info_structs, |
| * but folio_alloc_swap() doesn't need to look at full ones. |
| * This uses its own lock instead of swap_lock because when a |
| * swap_info_struct changes between not-full/full, it needs to |
| * add/remove itself to/from this list, but the swap_info_struct->lock |
| * is held and the locking order requires swap_lock to be taken |
| * before any swap_info_struct->lock. |
| */ |
| static struct plist_head *swap_avail_heads; |
| static DEFINE_SPINLOCK(swap_avail_lock); |
| |
| static struct swap_info_struct *swap_info[MAX_SWAPFILES]; |
| |
| static DEFINE_MUTEX(swapon_mutex); |
| |
| static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); |
| /* Activity counter to indicate that a swapon or swapoff has occurred */ |
| static atomic_t proc_poll_event = ATOMIC_INIT(0); |
| |
| atomic_t nr_rotate_swap = ATOMIC_INIT(0); |
| |
| static struct swap_info_struct *swap_type_to_swap_info(int type) |
| { |
| if (type >= MAX_SWAPFILES) |
| return NULL; |
| |
| return READ_ONCE(swap_info[type]); /* rcu_dereference() */ |
| } |
| |
| static inline unsigned char swap_count(unsigned char ent) |
| { |
| return ent & ~SWAP_HAS_CACHE; /* may include COUNT_CONTINUED flag */ |
| } |
| |
| /* Reclaim the swap entry anyway if possible */ |
| #define TTRS_ANYWAY 0x1 |
| /* |
| * Reclaim the swap entry if there are no more mappings of the |
| * corresponding page |
| */ |
| #define TTRS_UNMAPPED 0x2 |
| /* Reclaim the swap entry if swap is getting full */ |
| #define TTRS_FULL 0x4 |
| /* Reclaim directly, bypass the slot cache and don't touch device lock */ |
| #define TTRS_DIRECT 0x8 |
| |
| static bool swap_is_has_cache(struct swap_info_struct *si, |
| unsigned long offset, int nr_pages) |
| { |
| unsigned char *map = si->swap_map + offset; |
| unsigned char *map_end = map + nr_pages; |
| |
| do { |
| VM_BUG_ON(!(*map & SWAP_HAS_CACHE)); |
| if (*map != SWAP_HAS_CACHE) |
| return false; |
| } while (++map < map_end); |
| |
| return true; |
| } |
| |
| static bool swap_is_last_map(struct swap_info_struct *si, |
| unsigned long offset, int nr_pages, bool *has_cache) |
| { |
| unsigned char *map = si->swap_map + offset; |
| unsigned char *map_end = map + nr_pages; |
| unsigned char count = *map; |
| |
| if (swap_count(count) != 1) |
| return false; |
| |
| while (++map < map_end) { |
| if (*map != count) |
| return false; |
| } |
| |
| *has_cache = !!(count & SWAP_HAS_CACHE); |
| return true; |
| } |
| |
| /* |
| * returns number of pages in the folio that backs the swap entry. If positive, |
| * the folio was reclaimed. If negative, the folio was not reclaimed. If 0, no |
| * folio was associated with the swap entry. |
| */ |
| static int __try_to_reclaim_swap(struct swap_info_struct *si, |
| unsigned long offset, unsigned long flags) |
| { |
| swp_entry_t entry = swp_entry(si->type, offset); |
| struct address_space *address_space = swap_address_space(entry); |
| struct swap_cluster_info *ci; |
| struct folio *folio; |
| int ret, nr_pages; |
| bool need_reclaim; |
| |
| folio = filemap_get_folio(address_space, swap_cache_index(entry)); |
| if (IS_ERR(folio)) |
| return 0; |
| |
| nr_pages = folio_nr_pages(folio); |
| ret = -nr_pages; |
| |
| /* |
| * When this function is called from scan_swap_map_slots() and it's |
| * called by vmscan.c at reclaiming folios. So we hold a folio lock |
| * here. We have to use trylock for avoiding deadlock. This is a special |
| * case and you should use folio_free_swap() with explicit folio_lock() |
| * in usual operations. |
| */ |
| if (!folio_trylock(folio)) |
| goto out; |
| |
| /* offset could point to the middle of a large folio */ |
| entry = folio->swap; |
| offset = swp_offset(entry); |
| |
| need_reclaim = ((flags & TTRS_ANYWAY) || |
| ((flags & TTRS_UNMAPPED) && !folio_mapped(folio)) || |
| ((flags & TTRS_FULL) && mem_cgroup_swap_full(folio))); |
| if (!need_reclaim || !folio_swapcache_freeable(folio)) |
| goto out_unlock; |
| |
| /* |
| * It's safe to delete the folio from swap cache only if the folio's |
| * swap_map is HAS_CACHE only, which means the slots have no page table |
| * reference or pending writeback, and can't be allocated to others. |
| */ |
| ci = lock_cluster_or_swap_info(si, offset); |
| need_reclaim = swap_is_has_cache(si, offset, nr_pages); |
| unlock_cluster_or_swap_info(si, ci); |
| if (!need_reclaim) |
| goto out_unlock; |
| |
| if (!(flags & TTRS_DIRECT)) { |
| /* Free through slot cache */ |
| delete_from_swap_cache(folio); |
| folio_set_dirty(folio); |
| ret = nr_pages; |
| goto out_unlock; |
| } |
| |
| xa_lock_irq(&address_space->i_pages); |
| __delete_from_swap_cache(folio, entry, NULL); |
| xa_unlock_irq(&address_space->i_pages); |
| folio_ref_sub(folio, nr_pages); |
| folio_set_dirty(folio); |
| |
| spin_lock(&si->lock); |
| /* Only sinple page folio can be backed by zswap */ |
| if (nr_pages == 1) |
| zswap_invalidate(entry); |
| swap_entry_range_free(si, entry, nr_pages); |
| spin_unlock(&si->lock); |
| ret = nr_pages; |
| out_unlock: |
| folio_unlock(folio); |
| out: |
| folio_put(folio); |
| return ret; |
| } |
| |
| static inline struct swap_extent *first_se(struct swap_info_struct *sis) |
| { |
| struct rb_node *rb = rb_first(&sis->swap_extent_root); |
| return rb_entry(rb, struct swap_extent, rb_node); |
| } |
| |
| static inline struct swap_extent *next_se(struct swap_extent *se) |
| { |
| struct rb_node *rb = rb_next(&se->rb_node); |
| return rb ? rb_entry(rb, struct swap_extent, rb_node) : NULL; |
| } |
| |
| /* |
| * swapon tell device that all the old swap contents can be discarded, |
| * to allow the swap device to optimize its wear-levelling. |
| */ |
| static int discard_swap(struct swap_info_struct *si) |
| { |
| struct swap_extent *se; |
| sector_t start_block; |
| sector_t nr_blocks; |
| int err = 0; |
| |
| /* Do not discard the swap header page! */ |
| se = first_se(si); |
| start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); |
| nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); |
| if (nr_blocks) { |
| err = blkdev_issue_discard(si->bdev, start_block, |
| nr_blocks, GFP_KERNEL); |
| if (err) |
| return err; |
| cond_resched(); |
| } |
| |
| for (se = next_se(se); se; se = next_se(se)) { |
| start_block = se->start_block << (PAGE_SHIFT - 9); |
| nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); |
| |
| err = blkdev_issue_discard(si->bdev, start_block, |
| nr_blocks, GFP_KERNEL); |
| if (err) |
| break; |
| |
| cond_resched(); |
| } |
| return err; /* That will often be -EOPNOTSUPP */ |
| } |
| |
| static struct swap_extent * |
| offset_to_swap_extent(struct swap_info_struct *sis, unsigned long offset) |
| { |
| struct swap_extent *se; |
| struct rb_node *rb; |
| |
| rb = sis->swap_extent_root.rb_node; |
| while (rb) { |
| se = rb_entry(rb, struct swap_extent, rb_node); |
| if (offset < se->start_page) |
| rb = rb->rb_left; |
| else if (offset >= se->start_page + se->nr_pages) |
| rb = rb->rb_right; |
| else |
| return se; |
| } |
| /* It *must* be present */ |
| BUG(); |
| } |
| |
| sector_t swap_folio_sector(struct folio *folio) |
| { |
| struct swap_info_struct *sis = swp_swap_info(folio->swap); |
| struct swap_extent *se; |
| sector_t sector; |
| pgoff_t offset; |
| |
| offset = swp_offset(folio->swap); |
| se = offset_to_swap_extent(sis, offset); |
| sector = se->start_block + (offset - se->start_page); |
| return sector << (PAGE_SHIFT - 9); |
| } |
| |
| /* |
| * swap allocation tell device that a cluster of swap can now be discarded, |
| * to allow the swap device to optimize its wear-levelling. |
| */ |
| static void discard_swap_cluster(struct swap_info_struct *si, |
| pgoff_t start_page, pgoff_t nr_pages) |
| { |
| struct swap_extent *se = offset_to_swap_extent(si, start_page); |
| |
| while (nr_pages) { |
| pgoff_t offset = start_page - se->start_page; |
| sector_t start_block = se->start_block + offset; |
| sector_t nr_blocks = se->nr_pages - offset; |
| |
| if (nr_blocks > nr_pages) |
| nr_blocks = nr_pages; |
| start_page += nr_blocks; |
| nr_pages -= nr_blocks; |
| |
| start_block <<= PAGE_SHIFT - 9; |
| nr_blocks <<= PAGE_SHIFT - 9; |
| if (blkdev_issue_discard(si->bdev, start_block, |
| nr_blocks, GFP_NOIO)) |
| break; |
| |
| se = next_se(se); |
| } |
| } |
| |
| #ifdef CONFIG_THP_SWAP |
| #define SWAPFILE_CLUSTER HPAGE_PMD_NR |
| |
| #define swap_entry_order(order) (order) |
| #else |
| #define SWAPFILE_CLUSTER 256 |
| |
| /* |
| * Define swap_entry_order() as constant to let compiler to optimize |
| * out some code if !CONFIG_THP_SWAP |
| */ |
| #define swap_entry_order(order) 0 |
| #endif |
| #define LATENCY_LIMIT 256 |
| |
| static inline bool cluster_is_free(struct swap_cluster_info *info) |
| { |
| return info->flags & CLUSTER_FLAG_FREE; |
| } |
| |
| static inline unsigned int cluster_index(struct swap_info_struct *si, |
| struct swap_cluster_info *ci) |
| { |
| return ci - si->cluster_info; |
| } |
| |
| static inline unsigned int cluster_offset(struct swap_info_struct *si, |
| struct swap_cluster_info *ci) |
| { |
| return cluster_index(si, ci) * SWAPFILE_CLUSTER; |
| } |
| |
| static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si, |
| unsigned long offset) |
| { |
| struct swap_cluster_info *ci; |
| |
| ci = si->cluster_info; |
| if (ci) { |
| ci += offset / SWAPFILE_CLUSTER; |
| spin_lock(&ci->lock); |
| } |
| return ci; |
| } |
| |
| static inline void unlock_cluster(struct swap_cluster_info *ci) |
| { |
| if (ci) |
| spin_unlock(&ci->lock); |
| } |
| |
| /* |
| * Determine the locking method in use for this device. Return |
| * swap_cluster_info if SSD-style cluster-based locking is in place. |
| */ |
| static inline struct swap_cluster_info *lock_cluster_or_swap_info( |
| struct swap_info_struct *si, unsigned long offset) |
| { |
| struct swap_cluster_info *ci; |
| |
| /* Try to use fine-grained SSD-style locking if available: */ |
| ci = lock_cluster(si, offset); |
| /* Otherwise, fall back to traditional, coarse locking: */ |
| if (!ci) |
| spin_lock(&si->lock); |
| |
| return ci; |
| } |
| |
| static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si, |
| struct swap_cluster_info *ci) |
| { |
| if (ci) |
| unlock_cluster(ci); |
| else |
| spin_unlock(&si->lock); |
| } |
| |
| /* Add a cluster to discard list and schedule it to do discard */ |
| static void swap_cluster_schedule_discard(struct swap_info_struct *si, |
| struct swap_cluster_info *ci) |
| { |
| unsigned int idx = cluster_index(si, ci); |
| /* |
| * If scan_swap_map_slots() can't find a free cluster, it will check |
| * si->swap_map directly. To make sure the discarding cluster isn't |
| * taken by scan_swap_map_slots(), mark the swap entries bad (occupied). |
| * It will be cleared after discard |
| */ |
| memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
| SWAP_MAP_BAD, SWAPFILE_CLUSTER); |
| |
| VM_BUG_ON(ci->flags & CLUSTER_FLAG_FREE); |
| list_move_tail(&ci->list, &si->discard_clusters); |
| ci->flags = 0; |
| schedule_work(&si->discard_work); |
| } |
| |
| static void __free_cluster(struct swap_info_struct *si, struct swap_cluster_info *ci) |
| { |
| lockdep_assert_held(&si->lock); |
| lockdep_assert_held(&ci->lock); |
| |
| if (ci->flags) |
| list_move_tail(&ci->list, &si->free_clusters); |
| else |
| list_add_tail(&ci->list, &si->free_clusters); |
| ci->flags = CLUSTER_FLAG_FREE; |
| ci->order = 0; |
| } |
| |
| /* |
| * Doing discard actually. After a cluster discard is finished, the cluster |
| * will be added to free cluster list. caller should hold si->lock. |
| */ |
| static void swap_do_scheduled_discard(struct swap_info_struct *si) |
| { |
| struct swap_cluster_info *ci; |
| unsigned int idx; |
| |
| while (!list_empty(&si->discard_clusters)) { |
| ci = list_first_entry(&si->discard_clusters, struct swap_cluster_info, list); |
| list_del(&ci->list); |
| idx = cluster_index(si, ci); |
| spin_unlock(&si->lock); |
| |
| discard_swap_cluster(si, idx * SWAPFILE_CLUSTER, |
| SWAPFILE_CLUSTER); |
| |
| spin_lock(&si->lock); |
| spin_lock(&ci->lock); |
| __free_cluster(si, ci); |
| memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
| 0, SWAPFILE_CLUSTER); |
| spin_unlock(&ci->lock); |
| } |
| } |
| |
| static void swap_discard_work(struct work_struct *work) |
| { |
| struct swap_info_struct *si; |
| |
| si = container_of(work, struct swap_info_struct, discard_work); |
| |
| spin_lock(&si->lock); |
| swap_do_scheduled_discard(si); |
| spin_unlock(&si->lock); |
| } |
| |
| static void swap_users_ref_free(struct percpu_ref *ref) |
| { |
| struct swap_info_struct *si; |
| |
| si = container_of(ref, struct swap_info_struct, users); |
| complete(&si->comp); |
| } |
| |
| static void free_cluster(struct swap_info_struct *si, struct swap_cluster_info *ci) |
| { |
| VM_BUG_ON(ci->count != 0); |
| lockdep_assert_held(&si->lock); |
| lockdep_assert_held(&ci->lock); |
| |
| if (ci->flags & CLUSTER_FLAG_FRAG) |
| si->frag_cluster_nr[ci->order]--; |
| |
| /* |
| * If the swap is discardable, prepare discard the cluster |
| * instead of free it immediately. The cluster will be freed |
| * after discard. |
| */ |
| if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == |
| (SWP_WRITEOK | SWP_PAGE_DISCARD)) { |
| swap_cluster_schedule_discard(si, ci); |
| return; |
| } |
| |
| __free_cluster(si, ci); |
| } |
| |
| /* |
| * The cluster corresponding to page_nr will be used. The cluster will not be |
| * added to free cluster list and its usage counter will be increased by 1. |
| * Only used for initialization. |
| */ |
| static void inc_cluster_info_page(struct swap_info_struct *si, |
| struct swap_cluster_info *cluster_info, unsigned long page_nr) |
| { |
| unsigned long idx = page_nr / SWAPFILE_CLUSTER; |
| struct swap_cluster_info *ci; |
| |
| if (!cluster_info) |
| return; |
| |
| ci = cluster_info + idx; |
| ci->count++; |
| |
| VM_BUG_ON(ci->count > SWAPFILE_CLUSTER); |
| VM_BUG_ON(ci->flags); |
| } |
| |
| /* |
| * The cluster ci decreases @nr_pages usage. If the usage counter becomes 0, |
| * which means no page in the cluster is in use, we can optionally discard |
| * the cluster and add it to free cluster list. |
| */ |
| static void dec_cluster_info_page(struct swap_info_struct *si, |
| struct swap_cluster_info *ci, int nr_pages) |
| { |
| if (!si->cluster_info) |
| return; |
| |
| VM_BUG_ON(ci->count < nr_pages); |
| VM_BUG_ON(cluster_is_free(ci)); |
| lockdep_assert_held(&si->lock); |
| lockdep_assert_held(&ci->lock); |
| ci->count -= nr_pages; |
| |
| if (!ci->count) { |
| free_cluster(si, ci); |
| return; |
| } |
| |
| if (!(ci->flags & CLUSTER_FLAG_NONFULL)) { |
| VM_BUG_ON(ci->flags & CLUSTER_FLAG_FREE); |
| if (ci->flags & CLUSTER_FLAG_FRAG) |
| si->frag_cluster_nr[ci->order]--; |
| list_move_tail(&ci->list, &si->nonfull_clusters[ci->order]); |
| ci->flags = CLUSTER_FLAG_NONFULL; |
| } |
| } |
| |
| static bool cluster_reclaim_range(struct swap_info_struct *si, |
| struct swap_cluster_info *ci, |
| unsigned long start, unsigned long end) |
| { |
| unsigned char *map = si->swap_map; |
| unsigned long offset; |
| |
| spin_unlock(&ci->lock); |
| spin_unlock(&si->lock); |
| |
| for (offset = start; offset < end; offset++) { |
| switch (READ_ONCE(map[offset])) { |
| case 0: |
| continue; |
| case SWAP_HAS_CACHE: |
| if (__try_to_reclaim_swap(si, offset, TTRS_ANYWAY | TTRS_DIRECT) > 0) |
| continue; |
| goto out; |
| default: |
| goto out; |
| } |
| } |
| out: |
| spin_lock(&si->lock); |
| spin_lock(&ci->lock); |
| |
| /* |
| * Recheck the range no matter reclaim succeeded or not, the slot |
| * could have been be freed while we are not holding the lock. |
| */ |
| for (offset = start; offset < end; offset++) |
| if (READ_ONCE(map[offset])) |
| return false; |
| |
| return true; |
| } |
| |
| static bool cluster_scan_range(struct swap_info_struct *si, |
| struct swap_cluster_info *ci, |
| unsigned long start, unsigned int nr_pages) |
| { |
| unsigned long offset, end = start + nr_pages; |
| unsigned char *map = si->swap_map; |
| bool need_reclaim = false; |
| |
| for (offset = start; offset < end; offset++) { |
| switch (READ_ONCE(map[offset])) { |
| case 0: |
| continue; |
| case SWAP_HAS_CACHE: |
| if (!vm_swap_full()) |
| return false; |
| need_reclaim = true; |
| continue; |
| default: |
| return false; |
| } |
| } |
| |
| if (need_reclaim) |
| return cluster_reclaim_range(si, ci, start, end); |
| |
| return true; |
| } |
| |
| static void cluster_alloc_range(struct swap_info_struct *si, struct swap_cluster_info *ci, |
| unsigned int start, unsigned char usage, |
| unsigned int order) |
| { |
| unsigned int nr_pages = 1 << order; |
| |
| if (cluster_is_free(ci)) { |
| if (nr_pages < SWAPFILE_CLUSTER) { |
| list_move_tail(&ci->list, &si->nonfull_clusters[order]); |
| ci->flags = CLUSTER_FLAG_NONFULL; |
| } |
| ci->order = order; |
| } |
| |
| memset(si->swap_map + start, usage, nr_pages); |
| swap_range_alloc(si, start, nr_pages); |
| ci->count += nr_pages; |
| |
| if (ci->count == SWAPFILE_CLUSTER) { |
| VM_BUG_ON(!(ci->flags & |
| (CLUSTER_FLAG_FREE | CLUSTER_FLAG_NONFULL | CLUSTER_FLAG_FRAG))); |
| if (ci->flags & CLUSTER_FLAG_FRAG) |
| si->frag_cluster_nr[ci->order]--; |
| list_move_tail(&ci->list, &si->full_clusters); |
| ci->flags = CLUSTER_FLAG_FULL; |
| } |
| } |
| |
| static unsigned int alloc_swap_scan_cluster(struct swap_info_struct *si, unsigned long offset, |
| unsigned int *foundp, unsigned int order, |
| unsigned char usage) |
| { |
| unsigned long start = offset & ~(SWAPFILE_CLUSTER - 1); |
| unsigned long end = min(start + SWAPFILE_CLUSTER, si->max); |
| unsigned int nr_pages = 1 << order; |
| struct swap_cluster_info *ci; |
| |
| if (end < nr_pages) |
| return SWAP_NEXT_INVALID; |
| end -= nr_pages; |
| |
| ci = lock_cluster(si, offset); |
| if (ci->count + nr_pages > SWAPFILE_CLUSTER) { |
| offset = SWAP_NEXT_INVALID; |
| goto done; |
| } |
| |
| while (offset <= end) { |
| if (cluster_scan_range(si, ci, offset, nr_pages)) { |
| cluster_alloc_range(si, ci, offset, usage, order); |
| *foundp = offset; |
| if (ci->count == SWAPFILE_CLUSTER) { |
| offset = SWAP_NEXT_INVALID; |
| goto done; |
| } |
| offset += nr_pages; |
| break; |
| } |
| offset += nr_pages; |
| } |
| if (offset > end) |
| offset = SWAP_NEXT_INVALID; |
| done: |
| unlock_cluster(ci); |
| return offset; |
| } |
| |
| static void swap_reclaim_full_clusters(struct swap_info_struct *si) |
| { |
| long to_scan = 1; |
| unsigned long offset, end; |
| struct swap_cluster_info *ci; |
| unsigned char *map = si->swap_map; |
| int nr_reclaim, total_reclaimed = 0; |
| |
| if (atomic_long_read(&nr_swap_pages) <= SWAPFILE_CLUSTER) |
| to_scan = si->inuse_pages / SWAPFILE_CLUSTER; |
| |
| while (!list_empty(&si->full_clusters)) { |
| ci = list_first_entry(&si->full_clusters, struct swap_cluster_info, list); |
| list_move_tail(&ci->list, &si->full_clusters); |
| offset = cluster_offset(si, ci); |
| end = min(si->max, offset + SWAPFILE_CLUSTER); |
| to_scan--; |
| |
| while (offset < end) { |
| if (READ_ONCE(map[offset]) == SWAP_HAS_CACHE) { |
| spin_unlock(&si->lock); |
| nr_reclaim = __try_to_reclaim_swap(si, offset, |
| TTRS_ANYWAY | TTRS_DIRECT); |
| spin_lock(&si->lock); |
| if (nr_reclaim > 0) { |
| offset += nr_reclaim; |
| total_reclaimed += nr_reclaim; |
| continue; |
| } else if (nr_reclaim < 0) { |
| offset += -nr_reclaim; |
| continue; |
| } |
| } |
| offset++; |
| } |
| if (to_scan <= 0 || total_reclaimed) |
| break; |
| } |
| } |
| |
| /* |
| * Try to get swap entries with specified order from current cpu's swap entry |
| * pool (a cluster). This might involve allocating a new cluster for current CPU |
| * too. |
| */ |
| static unsigned long cluster_alloc_swap_entry(struct swap_info_struct *si, int order, |
| unsigned char usage) |
| { |
| struct percpu_cluster *cluster; |
| struct swap_cluster_info *ci; |
| unsigned int offset, found = 0; |
| |
| new_cluster: |
| lockdep_assert_held(&si->lock); |
| cluster = this_cpu_ptr(si->percpu_cluster); |
| offset = cluster->next[order]; |
| if (offset) { |
| offset = alloc_swap_scan_cluster(si, offset, &found, order, usage); |
| if (found) |
| goto done; |
| } |
| |
| if (!list_empty(&si->free_clusters)) { |
| ci = list_first_entry(&si->free_clusters, struct swap_cluster_info, list); |
| offset = alloc_swap_scan_cluster(si, cluster_offset(si, ci), &found, order, usage); |
| VM_BUG_ON(!found); |
| goto done; |
| } |
| |
| if (order < PMD_ORDER) { |
| unsigned int frags = 0; |
| |
| while (!list_empty(&si->nonfull_clusters[order])) { |
| ci = list_first_entry(&si->nonfull_clusters[order], |
| struct swap_cluster_info, list); |
| list_move_tail(&ci->list, &si->frag_clusters[order]); |
| ci->flags = CLUSTER_FLAG_FRAG; |
| si->frag_cluster_nr[order]++; |
| offset = alloc_swap_scan_cluster(si, cluster_offset(si, ci), |
| &found, order, usage); |
| frags++; |
| if (found) |
| break; |
| } |
| |
| if (!found) { |
| /* |
| * Nonfull clusters are moved to frag tail if we reached |
| * here, count them too, don't over scan the frag list. |
| */ |
| while (frags < si->frag_cluster_nr[order]) { |
| ci = list_first_entry(&si->frag_clusters[order], |
| struct swap_cluster_info, list); |
| /* |
| * Rotate the frag list to iterate, they were all failing |
| * high order allocation or moved here due to per-CPU usage, |
| * this help keeping usable cluster ahead. |
| */ |
| list_move_tail(&ci->list, &si->frag_clusters[order]); |
| offset = alloc_swap_scan_cluster(si, cluster_offset(si, ci), |
| &found, order, usage); |
| frags++; |
| if (found) |
| break; |
| } |
| } |
| } |
| |
| if (found) |
| goto done; |
| |
| if (!list_empty(&si->discard_clusters)) { |
| /* |
| * we don't have free cluster but have some clusters in |
| * discarding, do discard now and reclaim them, then |
| * reread cluster_next_cpu since we dropped si->lock |
| */ |
| swap_do_scheduled_discard(si); |
| goto new_cluster; |
| } |
| |
| if (order) |
| goto done; |
| |
| /* Order 0 stealing from higher order */ |
| for (int o = 1; o < SWAP_NR_ORDERS; o++) { |
| /* |
| * Clusters here have at least one usable slots and can't fail order 0 |
| * allocation, but reclaim may drop si->lock and race with another user. |
| */ |
| while (!list_empty(&si->frag_clusters[o])) { |
| ci = list_first_entry(&si->frag_clusters[o], |
| struct swap_cluster_info, list); |
| offset = alloc_swap_scan_cluster(si, cluster_offset(si, ci), |
| &found, 0, usage); |
| if (found) |
| goto done; |
| } |
| |
| while (!list_empty(&si->nonfull_clusters[o])) { |
| ci = list_first_entry(&si->nonfull_clusters[o], |
| struct swap_cluster_info, list); |
| offset = alloc_swap_scan_cluster(si, cluster_offset(si, ci), |
| &found, 0, usage); |
| if (found) |
| goto done; |
| } |
| } |
| |
| done: |
| /* Try reclaim from full clusters if device is nearfull */ |
| if (vm_swap_full() && (!found || (si->pages - si->inuse_pages) < SWAPFILE_CLUSTER)) { |
| swap_reclaim_full_clusters(si); |
| if (!found && !order && si->pages != si->inuse_pages) |
| goto new_cluster; |
| } |
| |
| cluster->next[order] = offset; |
| return found; |
| } |
| |
| static void __del_from_avail_list(struct swap_info_struct *si) |
| { |
| int nid; |
| |
| assert_spin_locked(&si->lock); |
| for_each_node(nid) |
| plist_del(&si->avail_lists[nid], &swap_avail_heads[nid]); |
| } |
| |
| static void del_from_avail_list(struct swap_info_struct *si) |
| { |
| spin_lock(&swap_avail_lock); |
| __del_from_avail_list(si); |
| spin_unlock(&swap_avail_lock); |
| } |
| |
| static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, |
| unsigned int nr_entries) |
| { |
| unsigned int end = offset + nr_entries - 1; |
| |
| if (offset == si->lowest_bit) |
| si->lowest_bit += nr_entries; |
| if (end == si->highest_bit) |
| WRITE_ONCE(si->highest_bit, si->highest_bit - nr_entries); |
| WRITE_ONCE(si->inuse_pages, si->inuse_pages + nr_entries); |
| if (si->inuse_pages == si->pages) { |
| si->lowest_bit = si->max; |
| si->highest_bit = 0; |
| del_from_avail_list(si); |
| } |
| } |
| |
| static void add_to_avail_list(struct swap_info_struct *si) |
| { |
| int nid; |
| |
| spin_lock(&swap_avail_lock); |
| for_each_node(nid) |
| plist_add(&si->avail_lists[nid], &swap_avail_heads[nid]); |
| spin_unlock(&swap_avail_lock); |
| } |
| |
| static void swap_range_free(struct swap_info_struct *si, unsigned long offset, |
| unsigned int nr_entries) |
| { |
| unsigned long begin = offset; |
| unsigned long end = offset + nr_entries - 1; |
| void (*swap_slot_free_notify)(struct block_device *, unsigned long); |
| unsigned int i; |
| |
| /* |
| * Use atomic clear_bit operations only on zeromap instead of non-atomic |
| * bitmap_clear to prevent adjacent bits corruption due to simultaneous writes. |
| */ |
| for (i = 0; i < nr_entries; i++) |
| clear_bit(offset + i, si->zeromap); |
| |
| if (offset < si->lowest_bit) |
| si->lowest_bit = offset; |
| if (end > si->highest_bit) { |
| bool was_full = !si->highest_bit; |
| |
| WRITE_ONCE(si->highest_bit, end); |
| if (was_full && (si->flags & SWP_WRITEOK)) |
| add_to_avail_list(si); |
| } |
| if (si->flags & SWP_BLKDEV) |
| swap_slot_free_notify = |
| si->bdev->bd_disk->fops->swap_slot_free_notify; |
| else |
| swap_slot_free_notify = NULL; |
| while (offset <= end) { |
| arch_swap_invalidate_page(si->type, offset); |
| if (swap_slot_free_notify) |
| swap_slot_free_notify(si->bdev, offset); |
| offset++; |
| } |
| clear_shadow_from_swap_cache(si->type, begin, end); |
| |
| /* |
| * Make sure that try_to_unuse() observes si->inuse_pages reaching 0 |
| * only after the above cleanups are done. |
| */ |
| smp_wmb(); |
| atomic_long_add(nr_entries, &nr_swap_pages); |
| WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries); |
| } |
| |
| static void set_cluster_next(struct swap_info_struct *si, unsigned long next) |
| { |
| unsigned long prev; |
| |
| if (!(si->flags & SWP_SOLIDSTATE)) { |
| si->cluster_next = next; |
| return; |
| } |
| |
| prev = this_cpu_read(*si->cluster_next_cpu); |
| /* |
| * Cross the swap address space size aligned trunk, choose |
| * another trunk randomly to avoid lock contention on swap |
| * address space if possible. |
| */ |
| if ((prev >> SWAP_ADDRESS_SPACE_SHIFT) != |
| (next >> SWAP_ADDRESS_SPACE_SHIFT)) { |
| /* No free swap slots available */ |
| if (si->highest_bit <= si->lowest_bit) |
| return; |
| next = get_random_u32_inclusive(si->lowest_bit, si->highest_bit); |
| next = ALIGN_DOWN(next, SWAP_ADDRESS_SPACE_PAGES); |
| next = max_t(unsigned int, next, si->lowest_bit); |
| } |
| this_cpu_write(*si->cluster_next_cpu, next); |
| } |
| |
| static bool swap_offset_available_and_locked(struct swap_info_struct *si, |
| unsigned long offset) |
| { |
| if (data_race(!si->swap_map[offset])) { |
| spin_lock(&si->lock); |
| return true; |
| } |
| |
| if (vm_swap_full() && READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) { |
| spin_lock(&si->lock); |
| return true; |
| } |
| |
| return false; |
| } |
| |
| static int cluster_alloc_swap(struct swap_info_struct *si, |
| unsigned char usage, int nr, |
| swp_entry_t slots[], int order) |
| { |
| int n_ret = 0; |
| |
| VM_BUG_ON(!si->cluster_info); |
| |
| while (n_ret < nr) { |
| unsigned long offset = cluster_alloc_swap_entry(si, order, usage); |
| |
| if (!offset) |
| break; |
| slots[n_ret++] = swp_entry(si->type, offset); |
| } |
| |
| return n_ret; |
| } |
| |
| static int scan_swap_map_slots(struct swap_info_struct *si, |
| unsigned char usage, int nr, |
| swp_entry_t slots[], int order) |
| { |
| unsigned long offset; |
| unsigned long scan_base; |
| unsigned long last_in_cluster = 0; |
| int latency_ration = LATENCY_LIMIT; |
| unsigned int nr_pages = 1 << order; |
| int n_ret = 0; |
| bool scanned_many = false; |
| |
| /* |
| * We try to cluster swap pages by allocating them sequentially |
| * in swap. Once we've allocated SWAPFILE_CLUSTER pages this |
| * way, however, we resort to first-free allocation, starting |
| * a new cluster. This prevents us from scattering swap pages |
| * all over the entire swap partition, so that we reduce |
| * overall disk seek times between swap pages. -- sct |
| * But we do now try to find an empty cluster. -Andrea |
| * And we let swap pages go all over an SSD partition. Hugh |
| */ |
| |
| if (order > 0) { |
| /* |
| * Should not even be attempting large allocations when huge |
| * page swap is disabled. Warn and fail the allocation. |
| */ |
| if (!IS_ENABLED(CONFIG_THP_SWAP) || |
| nr_pages > SWAPFILE_CLUSTER) { |
| VM_WARN_ON_ONCE(1); |
| return 0; |
| } |
| |
| /* |
| * Swapfile is not block device or not using clusters so unable |
| * to allocate large entries. |
| */ |
| if (!(si->flags & SWP_BLKDEV) || !si->cluster_info) |
| return 0; |
| } |
| |
| if (si->cluster_info) |
| return cluster_alloc_swap(si, usage, nr, slots, order); |
| |
| si->flags += SWP_SCANNING; |
| |
| /* For HDD, sequential access is more important. */ |
| scan_base = si->cluster_next; |
| offset = scan_base; |
| |
| if (unlikely(!si->cluster_nr--)) { |
| if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { |
| si->cluster_nr = SWAPFILE_CLUSTER - 1; |
| goto checks; |
| } |
| |
| spin_unlock(&si->lock); |
| |
| /* |
| * If seek is expensive, start searching for new cluster from |
| * start of partition, to minimize the span of allocated swap. |
| */ |
| scan_base = offset = si->lowest_bit; |
| last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
| |
| /* Locate the first empty (unaligned) cluster */ |
| for (; last_in_cluster <= READ_ONCE(si->highest_bit); offset++) { |
| if (si->swap_map[offset]) |
| last_in_cluster = offset + SWAPFILE_CLUSTER; |
| else if (offset == last_in_cluster) { |
| spin_lock(&si->lock); |
| offset -= SWAPFILE_CLUSTER - 1; |
| si->cluster_next = offset; |
| si->cluster_nr = SWAPFILE_CLUSTER - 1; |
| goto checks; |
| } |
| if (unlikely(--latency_ration < 0)) { |
| cond_resched(); |
| latency_ration = LATENCY_LIMIT; |
| } |
| } |
| |
| offset = scan_base; |
| spin_lock(&si->lock); |
| si->cluster_nr = SWAPFILE_CLUSTER - 1; |
| } |
| |
| checks: |
| if (!(si->flags & SWP_WRITEOK)) |
| goto no_page; |
| if (!si->highest_bit) |
| goto no_page; |
| if (offset > si->highest_bit) |
| scan_base = offset = si->lowest_bit; |
| |
| /* reuse swap entry of cache-only swap if not busy. */ |
| if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
| int swap_was_freed; |
| spin_unlock(&si->lock); |
| swap_was_freed = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY | TTRS_DIRECT); |
| spin_lock(&si->lock); |
| /* entry was freed successfully, try to use this again */ |
| if (swap_was_freed > 0) |
| goto checks; |
| goto scan; /* check next one */ |
| } |
| |
| if (si->swap_map[offset]) { |
| if (!n_ret) |
| goto scan; |
| else |
| goto done; |
| } |
| memset(si->swap_map + offset, usage, nr_pages); |
| |
| swap_range_alloc(si, offset, nr_pages); |
| slots[n_ret++] = swp_entry(si->type, offset); |
| |
| /* got enough slots or reach max slots? */ |
| if ((n_ret == nr) || (offset >= si->highest_bit)) |
| goto done; |
| |
| /* search for next available slot */ |
| |
| /* time to take a break? */ |
| if (unlikely(--latency_ration < 0)) { |
| if (n_ret) |
| goto done; |
| spin_unlock(&si->lock); |
| cond_resched(); |
| spin_lock(&si->lock); |
| latency_ration = LATENCY_LIMIT; |
| } |
| |
| if (si->cluster_nr && !si->swap_map[++offset]) { |
| /* non-ssd case, still more slots in cluster? */ |
| --si->cluster_nr; |
| goto checks; |
| } |
| |
| /* |
| * Even if there's no free clusters available (fragmented), |
| * try to scan a little more quickly with lock held unless we |
| * have scanned too many slots already. |
| */ |
| if (!scanned_many) { |
| unsigned long scan_limit; |
| |
| if (offset < scan_base) |
| scan_limit = scan_base; |
| else |
| scan_limit = si->highest_bit; |
| for (; offset <= scan_limit && --latency_ration > 0; |
| offset++) { |
| if (!si->swap_map[offset]) |
| goto checks; |
| } |
| } |
| |
| done: |
| if (order == 0) |
| set_cluster_next(si, offset + 1); |
| si->flags -= SWP_SCANNING; |
| return n_ret; |
| |
| scan: |
| VM_WARN_ON(order > 0); |
| spin_unlock(&si->lock); |
| while (++offset <= READ_ONCE(si->highest_bit)) { |
| if (unlikely(--latency_ration < 0)) { |
| cond_resched(); |
| latency_ration = LATENCY_LIMIT; |
| scanned_many = true; |
| } |
| if (swap_offset_available_and_locked(si, offset)) |
| goto checks; |
| } |
| offset = si->lowest_bit; |
| while (offset < scan_base) { |
| if (unlikely(--latency_ration < 0)) { |
| cond_resched(); |
| latency_ration = LATENCY_LIMIT; |
| scanned_many = true; |
| } |
| if (swap_offset_available_and_locked(si, offset)) |
| goto checks; |
| offset++; |
| } |
| spin_lock(&si->lock); |
| |
| no_page: |
| si->flags -= SWP_SCANNING; |
| return n_ret; |
| } |
| |
| int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_order) |
| { |
| int order = swap_entry_order(entry_order); |
| unsigned long size = 1 << order; |
| struct swap_info_struct *si, *next; |
| long avail_pgs; |
| int n_ret = 0; |
| int node; |
| |
| spin_lock(&swap_avail_lock); |
| |
| avail_pgs = atomic_long_read(&nr_swap_pages) / size; |
| if (avail_pgs <= 0) { |
| spin_unlock(&swap_avail_lock); |
| goto noswap; |
| } |
| |
| n_goal = min3((long)n_goal, (long)SWAP_BATCH, avail_pgs); |
| |
| atomic_long_sub(n_goal * size, &nr_swap_pages); |
| |
| start_over: |
| node = numa_node_id(); |
| plist_for_each_entry_safe(si, next, &swap_avail_heads[node], avail_lists[node]) { |
| /* requeue si to after same-priority siblings */ |
| plist_requeue(&si->avail_lists[node], &swap_avail_heads[node]); |
| spin_unlock(&swap_avail_lock); |
| spin_lock(&si->lock); |
| if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) { |
| spin_lock(&swap_avail_lock); |
| if (plist_node_empty(&si->avail_lists[node])) { |
| spin_unlock(&si->lock); |
| goto nextsi; |
| } |
| WARN(!si->highest_bit, |
| "swap_info %d in list but !highest_bit\n", |
| si->type); |
| WARN(!(si->flags & SWP_WRITEOK), |
| "swap_info %d in list but !SWP_WRITEOK\n", |
| si->type); |
| __del_from_avail_list(si); |
| spin_unlock(&si->lock); |
| goto nextsi; |
| } |
| n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, |
| n_goal, swp_entries, order); |
| spin_unlock(&si->lock); |
| if (n_ret || size > 1) |
| goto check_out; |
| cond_resched(); |
| |
| spin_lock(&swap_avail_lock); |
| nextsi: |
| /* |
| * if we got here, it's likely that si was almost full before, |
| * and since scan_swap_map_slots() can drop the si->lock, |
| * multiple callers probably all tried to get a page from the |
| * same si and it filled up before we could get one; or, the si |
| * filled up between us dropping swap_avail_lock and taking |
| * si->lock. Since we dropped the swap_avail_lock, the |
| * swap_avail_head list may have been modified; so if next is |
| * still in the swap_avail_head list then try it, otherwise |
| * start over if we have not gotten any slots. |
| */ |
| if (plist_node_empty(&next->avail_lists[node])) |
| goto start_over; |
| } |
| |
| spin_unlock(&swap_avail_lock); |
| |
| check_out: |
| if (n_ret < n_goal) |
| atomic_long_add((long)(n_goal - n_ret) * size, |
| &nr_swap_pages); |
| noswap: |
| return n_ret; |
| } |
| |
| static struct swap_info_struct *_swap_info_get(swp_entry_t entry) |
| { |
| struct swap_info_struct *si; |
| unsigned long offset; |
| |
| if (!entry.val) |
| goto out; |
| si = swp_swap_info(entry); |
| if (!si) |
| goto bad_nofile; |
| if (data_race(!(si->flags & SWP_USED))) |
| goto bad_device; |
| offset = swp_offset(entry); |
| if (offset >= si->max) |
| goto bad_offset; |
| if (data_race(!si->swap_map[swp_offset(entry)])) |
| goto bad_free; |
| return si; |
| |
| bad_free: |
| pr_err("%s: %s%08lx\n", __func__, Unused_offset, entry.val); |
| goto out; |
| bad_offset: |
| pr_err("%s: %s%08lx\n", __func__, Bad_offset, entry.val); |
| goto out; |
| bad_device: |
| pr_err("%s: %s%08lx\n", __func__, Unused_file, entry.val); |
| goto out; |
| bad_nofile: |
| pr_err("%s: %s%08lx\n", __func__, Bad_file, entry.val); |
| out: |
| return NULL; |
| } |
| |
| static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry, |
| struct swap_info_struct *q) |
| { |
| struct swap_info_struct *p; |
| |
| p = _swap_info_get(entry); |
| |
| if (p != q) { |
| if (q != NULL) |
| spin_unlock(&q->lock); |
| if (p != NULL) |
| spin_lock(&p->lock); |
| } |
| return p; |
| } |
| |
| static unsigned char __swap_entry_free_locked(struct swap_info_struct *si, |
| unsigned long offset, |
| unsigned char usage) |
| { |
| unsigned char count; |
| unsigned char has_cache; |
| |
| count = si->swap_map[offset]; |
| |
| has_cache = count & SWAP_HAS_CACHE; |
| count &= ~SWAP_HAS_CACHE; |
| |
| if (usage == SWAP_HAS_CACHE) { |
| VM_BUG_ON(!has_cache); |
| has_cache = 0; |
| } else if (count == SWAP_MAP_SHMEM) { |
| /* |
| * Or we could insist on shmem.c using a special |
| * swap_shmem_free() and free_shmem_swap_and_cache()... |
| */ |
| count = 0; |
| } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { |
| if (count == COUNT_CONTINUED) { |
| if (swap_count_continued(si, offset, count)) |
| count = SWAP_MAP_MAX | COUNT_CONTINUED; |
| else |
| count = SWAP_MAP_MAX; |
| } else |
| count--; |
| } |
| |
| usage = count | has_cache; |
| if (usage) |
| WRITE_ONCE(si->swap_map[offset], usage); |
| else |
| WRITE_ONCE(si->swap_map[offset], SWAP_HAS_CACHE); |
| |
| return usage; |
| } |
| |
| /* |
| * When we get a swap entry, if there aren't some other ways to |
| * prevent swapoff, such as the folio in swap cache is locked, RCU |
| * reader side is locked, etc., the swap entry may become invalid |
| * because of swapoff. Then, we need to enclose all swap related |
| * functions with get_swap_device() and put_swap_device(), unless the |
| * swap functions call get/put_swap_device() by themselves. |
| * |
| * RCU reader side lock (including any spinlock) is sufficient to |
| * prevent swapoff, because synchronize_rcu() is called in swapoff() |
| * before freeing data structures. |
| * |
| * Check whether swap entry is valid in the swap device. If so, |
| * return pointer to swap_info_struct, and keep the swap entry valid |
| * via preventing the swap device from being swapoff, until |
| * put_swap_device() is called. Otherwise return NULL. |
| * |
| * Notice that swapoff or swapoff+swapon can still happen before the |
| * percpu_ref_tryget_live() in get_swap_device() or after the |
| * percpu_ref_put() in put_swap_device() if there isn't any other way |
| * to prevent swapoff. The caller must be prepared for that. For |
| * example, the following situation is possible. |
| * |
| * CPU1 CPU2 |
| * do_swap_page() |
| * ... swapoff+swapon |
| * __read_swap_cache_async() |
| * swapcache_prepare() |
| * __swap_duplicate() |
| * // check swap_map |
| * // verify PTE not changed |
| * |
| * In __swap_duplicate(), the swap_map need to be checked before |
| * changing partly because the specified swap entry may be for another |
| * swap device which has been swapoff. And in do_swap_page(), after |
| * the page is read from the swap device, the PTE is verified not |
| * changed with the page table locked to check whether the swap device |
| * has been swapoff or swapoff+swapon. |
| */ |
| struct swap_info_struct *get_swap_device(swp_entry_t entry) |
| { |
| struct swap_info_struct *si; |
| unsigned long offset; |
| |
| if (!entry.val) |
| goto out; |
| si = swp_swap_info(entry); |
| if (!si) |
| goto bad_nofile; |
| if (!percpu_ref_tryget_live(&si->users)) |
| goto out; |
| /* |
| * Guarantee the si->users are checked before accessing other |
| * fields of swap_info_struct. |
| * |
| * Paired with the spin_unlock() after setup_swap_info() in |
| * enable_swap_info(). |
| */ |
| smp_rmb(); |
| offset = swp_offset(entry); |
| if (offset >= si->max) |
| goto put_out; |
| |
| return si; |
| bad_nofile: |
| pr_err("%s: %s%08lx\n", __func__, Bad_file, entry.val); |
| out: |
| return NULL; |
| put_out: |
| pr_err("%s: %s%08lx\n", __func__, Bad_offset, entry.val); |
| percpu_ref_put(&si->users); |
| return NULL; |
| } |
| |
| static unsigned char __swap_entry_free(struct swap_info_struct *si, |
| swp_entry_t entry) |
| { |
| struct swap_cluster_info *ci; |
| unsigned long offset = swp_offset(entry); |
| unsigned char usage; |
| |
| ci = lock_cluster_or_swap_info(si, offset); |
| usage = __swap_entry_free_locked(si, offset, 1); |
| unlock_cluster_or_swap_info(si, ci); |
| if (!usage) |
| free_swap_slot(entry); |
| |
| return usage; |
| } |
| |
| static bool __swap_entries_free(struct swap_info_struct *si, |
| swp_entry_t entry, int nr) |
| { |
| unsigned long offset = swp_offset(entry); |
| unsigned int type = swp_type(entry); |
| struct swap_cluster_info *ci; |
| bool has_cache = false; |
| unsigned char count; |
| int i; |
| |
| if (nr <= 1 || swap_count(data_race(si->swap_map[offset])) != 1) |
| goto fallback; |
| /* cross into another cluster */ |
| if (nr > SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER) |
| goto fallback; |
| |
| ci = lock_cluster_or_swap_info(si, offset); |
| if (!swap_is_last_map(si, offset, nr, &has_cache)) { |
| unlock_cluster_or_swap_info(si, ci); |
| goto fallback; |
| } |
| for (i = 0; i < nr; i++) |
| WRITE_ONCE(si->swap_map[offset + i], SWAP_HAS_CACHE); |
| unlock_cluster_or_swap_info(si, ci); |
| |
| if (!has_cache) { |
| for (i = 0; i < nr; i++) |
| zswap_invalidate(swp_entry(si->type, offset + i)); |
| spin_lock(&si->lock); |
| swap_entry_range_free(si, entry, nr); |
| spin_unlock(&si->lock); |
| } |
| return has_cache; |
| |
| fallback: |
| for (i = 0; i < nr; i++) { |
| if (data_race(si->swap_map[offset + i])) { |
| count = __swap_entry_free(si, swp_entry(type, offset + i)); |
| if (count == SWAP_HAS_CACHE) |
| has_cache = true; |
| } else { |
| WARN_ON_ONCE(1); |
| } |
| } |
| return has_cache; |
| } |
| |
| /* |
| * Drop the last HAS_CACHE flag of swap entries, caller have to |
| * ensure all entries belong to the same cgroup. |
| */ |
| static void swap_entry_range_free(struct swap_info_struct *si, swp_entry_t entry, |
| unsigned int nr_pages) |
| { |
| unsigned long offset = swp_offset(entry); |
| unsigned char *map = si->swap_map + offset; |
| unsigned char *map_end = map + nr_pages; |
| struct swap_cluster_info *ci; |
| |
| ci = lock_cluster(si, offset); |
| do { |
| VM_BUG_ON(*map != SWAP_HAS_CACHE); |
| *map = 0; |
| } while (++map < map_end); |
| dec_cluster_info_page(si, ci, nr_pages); |
| unlock_cluster(ci); |
| |
| mem_cgroup_uncharge_swap(entry, nr_pages); |
| swap_range_free(si, offset, nr_pages); |
| } |
| |
| static void cluster_swap_free_nr(struct swap_info_struct *si, |
| unsigned long offset, int nr_pages, |
| unsigned char usage) |
| { |
| struct swap_cluster_info *ci; |
| DECLARE_BITMAP(to_free, BITS_PER_LONG) = { 0 }; |
| int i, nr; |
| |
| ci = lock_cluster_or_swap_info(si, offset); |
| while (nr_pages) { |
| nr = min(BITS_PER_LONG, nr_pages); |
| for (i = 0; i < nr; i++) { |
| if (!__swap_entry_free_locked(si, offset + i, usage)) |
| bitmap_set(to_free, i, 1); |
| } |
| if (!bitmap_empty(to_free, BITS_PER_LONG)) { |
| unlock_cluster_or_swap_info(si, ci); |
| for_each_set_bit(i, to_free, BITS_PER_LONG) |
| free_swap_slot(swp_entry(si->type, offset + i)); |
| if (nr == nr_pages) |
| return; |
| bitmap_clear(to_free, 0, BITS_PER_LONG); |
| ci = lock_cluster_or_swap_info(si, offset); |
| } |
| offset += nr; |
| nr_pages -= nr; |
| } |
| unlock_cluster_or_swap_info(si, ci); |
| } |
| |
| /* |
| * Caller has made sure that the swap device corresponding to entry |
| * is still around or has not been recycled. |
| */ |
| void swap_free_nr(swp_entry_t entry, int nr_pages) |
| { |
| int nr; |
| struct swap_info_struct *sis; |
| unsigned long offset = swp_offset(entry); |
| |
| sis = _swap_info_get(entry); |
| if (!sis) |
| return; |
| |
| while (nr_pages) { |
| nr = min_t(int, nr_pages, SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER); |
| cluster_swap_free_nr(sis, offset, nr, 1); |
| offset += nr; |
| nr_pages -= nr; |
| } |
| } |
| |
| /* |
| * Called after dropping swapcache to decrease refcnt to swap entries. |
| */ |
| void put_swap_folio(struct folio *folio, swp_entry_t entry) |
| { |
| unsigned long offset = swp_offset(entry); |
| struct swap_cluster_info *ci; |
| struct swap_info_struct *si; |
| int size = 1 << swap_entry_order(folio_order(folio)); |
| |
| si = _swap_info_get(entry); |
| if (!si) |
| return; |
| |
| ci = lock_cluster_or_swap_info(si, offset); |
| if (size > 1 && swap_is_has_cache(si, offset, size)) { |
| unlock_cluster_or_swap_info(si, ci); |
| spin_lock(&si->lock); |
| swap_entry_range_free(si, entry, size); |
| spin_unlock(&si->lock); |
| return; |
| } |
| for (int i = 0; i < size; i++, entry.val++) { |
| if (!__swap_entry_free_locked(si, offset + i, SWAP_HAS_CACHE)) { |
| unlock_cluster_or_swap_info(si, ci); |
| free_swap_slot(entry); |
| if (i == size - 1) |
| return; |
| lock_cluster_or_swap_info(si, offset); |
| } |
| } |
| unlock_cluster_or_swap_info(si, ci); |
| } |
| |
| static int swp_entry_cmp(const void *ent1, const void *ent2) |
| { |
| const swp_entry_t *e1 = ent1, *e2 = ent2; |
| |
| return (int)swp_type(*e1) - (int)swp_type(*e2); |
| } |
| |
| void swapcache_free_entries(swp_entry_t *entries, int n) |
| { |
| struct swap_info_struct *p, *prev; |
| int i; |
| |
| if (n <= 0) |
| return; |
| |
| prev = NULL; |
| p = NULL; |
| |
| /* |
| * Sort swap entries by swap device, so each lock is only taken once. |
| * nr_swapfiles isn't absolutely correct, but the overhead of sort() is |
| * so low that it isn't necessary to optimize further. |
| */ |
| if (nr_swapfiles > 1) |
| sort(entries, n, sizeof(entries[0]), swp_entry_cmp, NULL); |
| for (i = 0; i < n; ++i) { |
| p = swap_info_get_cont(entries[i], prev); |
| if (p) |
| swap_entry_range_free(p, entries[i], 1); |
| prev = p; |
| } |
| if (p) |
| spin_unlock(&p->lock); |
| } |
| |
| int __swap_count(swp_entry_t entry) |
| { |
| struct swap_info_struct *si = swp_swap_info(entry); |
| pgoff_t offset = swp_offset(entry); |
| |
| return swap_count(si->swap_map[offset]); |
| } |
| |
| /* |
| * How many references to @entry are currently swapped out? |
| * This does not give an exact answer when swap count is continued, |
| * but does include the high COUNT_CONTINUED flag to allow for that. |
| */ |
| int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry) |
| { |
| pgoff_t offset = swp_offset(entry); |
| struct swap_cluster_info *ci; |
| int count; |
| |
| ci = lock_cluster_or_swap_info(si, offset); |
| count = swap_count(si->swap_map[offset]); |
| unlock_cluster_or_swap_info(si, ci); |
| return count; |
| } |
| |
| /* |
| * How many references to @entry are currently swapped out? |
| * This considers COUNT_CONTINUED so it returns exact answer. |
| */ |
| int swp_swapcount(swp_entry_t entry) |
| { |
| int count, tmp_count, n; |
| struct swap_info_struct *si; |
| struct swap_cluster_info *ci; |
| struct page *page; |
| pgoff_t offset; |
| unsigned char *map; |
| |
| si = _swap_info_get(entry); |
| if (!si) |
| return 0; |
| |
| offset = swp_offset(entry); |
| |
| ci = lock_cluster_or_swap_info(si, offset); |
| |
| count = swap_count(si->swap_map[offset]); |
| if (!(count & COUNT_CONTINUED)) |
| goto out; |
| |
| count &= ~COUNT_CONTINUED; |
| n = SWAP_MAP_MAX + 1; |
| |
| page = vmalloc_to_page(si->swap_map + offset); |
| offset &= ~PAGE_MASK; |
| VM_BUG_ON(page_private(page) != SWP_CONTINUED); |
| |
| do { |
| page = list_next_entry(page, lru); |
| map = kmap_local_page(page); |
| tmp_count = map[offset]; |
| kunmap_local(map); |
| |
| count += (tmp_count & ~COUNT_CONTINUED) * n; |
| n *= (SWAP_CONT_MAX + 1); |
| } while (tmp_count & COUNT_CONTINUED); |
| out: |
| unlock_cluster_or_swap_info(si, ci); |
| return count; |
| } |
| |
| static bool swap_page_trans_huge_swapped(struct swap_info_struct *si, |
| swp_entry_t entry, int order) |
| { |
| struct swap_cluster_info *ci; |
| unsigned char *map = si->swap_map; |
| unsigned int nr_pages = 1 << order; |
| unsigned long roffset = swp_offset(entry); |
| unsigned long offset = round_down(roffset, nr_pages); |
| int i; |
| bool ret = false; |
| |
| ci = lock_cluster_or_swap_info(si, offset); |
| if (!ci || nr_pages == 1) { |
| if (swap_count(map[roffset])) |
| ret = true; |
| goto unlock_out; |
| } |
| for (i = 0; i < nr_pages; i++) { |
| if (swap_count(map[offset + i])) { |
| ret = true; |
| break; |
| } |
| } |
| unlock_out: |
| unlock_cluster_or_swap_info(si, ci); |
| return ret; |
| } |
| |
| static bool folio_swapped(struct folio *folio) |
| { |
| swp_entry_t entry = folio->swap; |
| struct swap_info_struct *si = _swap_info_get(entry); |
| |
| if (!si) |
| return false; |
| |
| if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!folio_test_large(folio))) |
| return swap_swapcount(si, entry) != 0; |
| |
| return swap_page_trans_huge_swapped(si, entry, folio_order(folio)); |
| } |
| |
| static bool folio_swapcache_freeable(struct folio *folio) |
| { |
| VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); |
| |
| if (!folio_test_swapcache(folio)) |
| return false; |
| if (folio_test_writeback(folio)) |
| return false; |
| |
| /* |
| * Once hibernation has begun to create its image of memory, |
| * there's a danger that one of the calls to folio_free_swap() |
| * - most probably a call from __try_to_reclaim_swap() while |
| * hibernation is allocating its own swap pages for the image, |
| * but conceivably even a call from memory reclaim - will free |
| * the swap from a folio which has already been recorded in the |
| * image as a clean swapcache folio, and then reuse its swap for |
| * another page of the image. On waking from hibernation, the |
| * original folio might be freed under memory pressure, then |
| * later read back in from swap, now with the wrong data. |
| * |
| * Hibernation suspends storage while it is writing the image |
| * to disk so check that here. |
| */ |
| if (pm_suspended_storage()) |
| return false; |
| |
| return true; |
| } |
| |
| /** |
| * folio_free_swap() - Free the swap space used for this folio. |
| * @folio: The folio to remove. |
| * |
| * If swap is getting full, or if there are no more mappings of this folio, |
| * then call folio_free_swap to free its swap space. |
| * |
| * Return: true if we were able to release the swap space. |
| */ |
| bool folio_free_swap(struct folio *folio) |
| { |
| if (!folio_swapcache_freeable(folio)) |
| return false; |
| if (folio_swapped(folio)) |
| return false; |
| |
| delete_from_swap_cache(folio); |
| folio_set_dirty(folio); |
| return true; |
| } |
| |
| /** |
| * free_swap_and_cache_nr() - Release reference on range of swap entries and |
| * reclaim their cache if no more references remain. |
| * @entry: First entry of range. |
| * @nr: Number of entries in range. |
| * |
| * For each swap entry in the contiguous range, release a reference. If any swap |
| * entries become free, try to reclaim their underlying folios, if present. The |
| * offset range is defined by [entry.offset, entry.offset + nr). |
| */ |
| void free_swap_and_cache_nr(swp_entry_t entry, int nr) |
| { |
| const unsigned long start_offset = swp_offset(entry); |
| const unsigned long end_offset = start_offset + nr; |
| struct swap_info_struct *si; |
| bool any_only_cache = false; |
| unsigned long offset; |
| |
| if (non_swap_entry(entry)) |
| return; |
| |
| si = get_swap_device(entry); |
| if (!si) |
| return; |
| |
| if (WARN_ON(end_offset > si->max)) |
| goto out; |
| |
| /* |
| * First free all entries in the range. |
| */ |
| any_only_cache = __swap_entries_free(si, entry, nr); |
| |
| /* |
| * Short-circuit the below loop if none of the entries had their |
| * reference drop to zero. |
| */ |
| if (!any_only_cache) |
| goto out; |
| |
| /* |
| * Now go back over the range trying to reclaim the swap cache. This is |
| * more efficient for large folios because we will only try to reclaim |
| * the swap once per folio in the common case. If we do |
| * __swap_entry_free() and __try_to_reclaim_swap() in the same loop, the |
| * latter will get a reference and lock the folio for every individual |
| * page but will only succeed once the swap slot for every subpage is |
| * zero. |
| */ |
| for (offset = start_offset; offset < end_offset; offset += nr) { |
| nr = 1; |
| if (READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) { |
| /* |
| * Folios are always naturally aligned in swap so |
| * advance forward to the next boundary. Zero means no |
| * folio was found for the swap entry, so advance by 1 |
| * in this case. Negative value means folio was found |
| * but could not be reclaimed. Here we can still advance |
| * to the next boundary. |
| */ |
| nr = __try_to_reclaim_swap(si, offset, |
| TTRS_UNMAPPED | TTRS_FULL); |
| if (nr == 0) |
| nr = 1; |
| else if (nr < 0) |
| nr = -nr; |
| nr = ALIGN(offset + 1, nr) - offset; |
| } |
| } |
| |
| out: |
| put_swap_device(si); |
| } |
| |
| #ifdef CONFIG_HIBERNATION |
| |
| swp_entry_t get_swap_page_of_type(int type) |
| { |
| struct swap_info_struct *si = swap_type_to_swap_info(type); |
| swp_entry_t entry = {0}; |
| |
| if (!si) |
| goto fail; |
| |
| /* This is called for allocating swap entry, not cache */ |
| spin_lock(&si->lock); |
| if ((si->flags & SWP_WRITEOK) && scan_swap_map_slots(si, 1, 1, &entry, 0)) |
| atomic_long_dec(&nr_swap_pages); |
| spin_unlock(&si->lock); |
| fail: |
| return entry; |
| } |
| |
| /* |
| * Find the swap type that corresponds to given device (if any). |
| * |
| * @offset - number of the PAGE_SIZE-sized block of the device, starting |
| * from 0, in which the swap header is expected to be located. |
| * |
| * This is needed for the suspend to disk (aka swsusp). |
| */ |
| int swap_type_of(dev_t device, sector_t offset) |
| { |
| int type; |
| |
| if (!device) |
| return -1; |
| |
| spin_lock(&swap_lock); |
| for (type = 0; type < nr_swapfiles; type++) { |
| struct swap_info_struct *sis = swap_info[type]; |
| |
| if (!(sis->flags & SWP_WRITEOK)) |
| continue; |
| |
| if (device == sis->bdev->bd_dev) { |
| struct swap_extent *se = first_se(sis); |
| |
| if (se->start_block == offset) { |
| spin_unlock(&swap_lock); |
| return type; |
| } |
| } |
| } |
| spin_unlock(&swap_lock); |
| return -ENODEV; |
| } |
| |
| int find_first_swap(dev_t *device) |
| { |
| int type; |
| |
| spin_lock(&swap_lock); |
| for (type = 0; type < nr_swapfiles; type++) { |
| struct swap_info_struct *sis = swap_info[type]; |
| |
| if (!(sis->flags & SWP_WRITEOK)) |
| continue; |
| *device = sis->bdev->bd_dev; |
| spin_unlock(&swap_lock); |
| return type; |
| } |
| spin_unlock(&swap_lock); |
| return -ENODEV; |
| } |
| |
| /* |
| * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev |
| * corresponding to given index in swap_info (swap type). |
| */ |
| sector_t swapdev_block(int type, pgoff_t offset) |
| { |
| struct swap_info_struct *si = swap_type_to_swap_info(type); |
| struct swap_extent *se; |
| |
| if (!si || !(si->flags & SWP_WRITEOK)) |
| return 0; |
| se = offset_to_swap_extent(si, offset); |
| return se->start_block + (offset - se->start_page); |
| } |
| |
| /* |
| * Return either the total number of swap pages of given type, or the number |
| * of free pages of that type (depending on @free) |
| * |
| * This is needed for software suspend |
| */ |
| unsigned int count_swap_pages(int type, int free) |
| { |
| unsigned int n = 0; |
| |
| spin_lock(&swap_lock); |
| if ((unsigned int)type < nr_swapfiles) { |
| struct swap_info_struct *sis = swap_info[type]; |
| |
| spin_lock(&sis->lock); |
| if (sis->flags & SWP_WRITEOK) { |
| n = sis->pages; |
| if (free) |
| n -= sis->inuse_pages; |
| } |
| spin_unlock(&sis->lock); |
| } |
| spin_unlock(&swap_lock); |
| return n; |
| } |
| #endif /* CONFIG_HIBERNATION */ |
| |
| static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte) |
| { |
| return pte_same(pte_swp_clear_flags(pte), swp_pte); |
| } |
| |
| /* |
| * No need to decide whether this PTE shares the swap entry with others, |
| * just let do_wp_page work it out if a write is requested later - to |
| * force COW, vm_page_prot omits write permission from any private vma. |
| */ |
| static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long addr, swp_entry_t entry, struct folio *folio) |
| { |
| struct page *page; |
| struct folio *swapcache; |
| spinlock_t *ptl; |
| pte_t *pte, new_pte, old_pte; |
| bool hwpoisoned = false; |
| int ret = 1; |
| |
| swapcache = folio; |
| folio = ksm_might_need_to_copy(folio, vma, addr); |
| if (unlikely(!folio)) |
| return -ENOMEM; |
| else if (unlikely(folio == ERR_PTR(-EHWPOISON))) { |
| hwpoisoned = true; |
| folio = swapcache; |
| } |
| |
| page = folio_file_page(folio, swp_offset(entry)); |
| if (PageHWPoison(page)) |
| hwpoisoned = true; |
| |
| pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); |
| if (unlikely(!pte || !pte_same_as_swp(ptep_get(pte), |
| swp_entry_to_pte(entry)))) { |
| ret = 0; |
| goto out; |
| } |
| |
| old_pte = ptep_get(pte); |
| |
| if (unlikely(hwpoisoned || !folio_test_uptodate(folio))) { |
| swp_entry_t swp_entry; |
| |
| dec_mm_counter(vma->vm_mm, MM_SWAPENTS); |
| if (hwpoisoned) { |
| swp_entry = make_hwpoison_entry(page); |
| } else { |
| swp_entry = make_poisoned_swp_entry(); |
| } |
| new_pte = swp_entry_to_pte(swp_entry); |
| ret = 0; |
| goto setpte; |
| } |
| |
| /* |
| * Some architectures may have to restore extra metadata to the page |
| * when reading from swap. This metadata may be indexed by swap entry |
| * so this must be called before swap_free(). |
| */ |
| arch_swap_restore(folio_swap(entry, folio), folio); |
| |
| dec_mm_counter(vma->vm_mm, MM_SWAPENTS); |
| inc_mm_counter(vma->vm_mm, MM_ANONPAGES); |
| folio_get(folio); |
| if (folio == swapcache) { |
| rmap_t rmap_flags = RMAP_NONE; |
| |
| /* |
| * See do_swap_page(): writeback would be problematic. |
| * However, we do a folio_wait_writeback() just before this |
| * call and have the folio locked. |
| */ |
| VM_BUG_ON_FOLIO(folio_test_writeback(folio), folio); |
| if (pte_swp_exclusive(old_pte)) |
| rmap_flags |= RMAP_EXCLUSIVE; |
| /* |
| * We currently only expect small !anon folios, which are either |
| * fully exclusive or fully shared. If we ever get large folios |
| * here, we have to be careful. |
| */ |
| if (!folio_test_anon(folio)) { |
| VM_WARN_ON_ONCE(folio_test_large(folio)); |
| VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); |
| folio_add_new_anon_rmap(folio, vma, addr, rmap_flags); |
| } else { |
| folio_add_anon_rmap_pte(folio, page, vma, addr, rmap_flags); |
| } |
| } else { /* ksm created a completely new copy */ |
| folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE); |
| folio_add_lru_vma(folio, vma); |
| } |
| new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot)); |
| if (pte_swp_soft_dirty(old_pte)) |
| new_pte = pte_mksoft_dirty(new_pte); |
| if (pte_swp_uffd_wp(old_pte)) |
| new_pte = pte_mkuffd_wp(new_pte); |
| setpte: |
| set_pte_at(vma->vm_mm, addr, pte, new_pte); |
| swap_free(entry); |
| out: |
| if (pte) |
| pte_unmap_unlock(pte, ptl); |
| if (folio != swapcache) { |
| folio_unlock(folio); |
| folio_put(folio); |
| } |
| return ret; |
| } |
| |
| static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| unsigned int type) |
| { |
| pte_t *pte = NULL; |
| struct swap_info_struct *si; |
| |
| si = swap_info[type]; |
| do { |
| struct folio *folio; |
| unsigned long offset; |
| unsigned char swp_count; |
| swp_entry_t entry; |
| int ret; |
| pte_t ptent; |
| |
| if (!pte++) { |
| pte = pte_offset_map(pmd, addr); |
| if (!pte) |
| break; |
| } |
| |
| ptent = ptep_get_lockless(pte); |
| |
| if (!is_swap_pte(ptent)) |
| continue; |
| |
| entry = pte_to_swp_entry(ptent); |
| if (swp_type(entry) != type) |
| continue; |
| |
| offset = swp_offset(entry); |
| pte_unmap(pte); |
| pte = NULL; |
| |
| folio = swap_cache_get_folio(entry, vma, addr); |
| if (!folio) { |
| struct vm_fault vmf = { |
| .vma = vma, |
| .address = addr, |
| .real_address = addr, |
| .pmd = pmd, |
| }; |
| |
| folio = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, |
| &vmf); |
| } |
| if (!folio) { |
| swp_count = READ_ONCE(si->swap_map[offset]); |
| if (swp_count == 0 || swp_count == SWAP_MAP_BAD) |
| continue; |
| return -ENOMEM; |
| } |
| |
| folio_lock(folio); |
| folio_wait_writeback(folio); |
| ret = unuse_pte(vma, pmd, addr, entry, folio); |
| if (ret < 0) { |
| folio_unlock(folio); |
| folio_put(folio); |
| return ret; |
| } |
| |
| folio_free_swap(folio); |
| folio_unlock(folio); |
| folio_put(folio); |
| } while (addr += PAGE_SIZE, addr != end); |
| |
| if (pte) |
| pte_unmap(pte); |
| return 0; |
| } |
| |
| static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| unsigned int type) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| int ret; |
| |
| pmd = pmd_offset(pud, addr); |
| do { |
| cond_resched(); |
| next = pmd_addr_end(addr, end); |
| ret = unuse_pte_range(vma, pmd, addr, next, type); |
| if (ret) |
| return ret; |
| } while (pmd++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int unuse_pud_range(struct vm_area_struct *vma, p4d_t *p4d, |
| unsigned long addr, unsigned long end, |
| unsigned int type) |
| { |
| pud_t *pud; |
| unsigned long next; |
| int ret; |
| |
| pud = pud_offset(p4d, addr); |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_none_or_clear_bad(pud)) |
| continue; |
| ret = unuse_pmd_range(vma, pud, addr, next, type); |
| if (ret) |
| return ret; |
| } while (pud++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int unuse_p4d_range(struct vm_area_struct *vma, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| unsigned int type) |
| { |
| p4d_t *p4d; |
| unsigned long next; |
| int ret; |
| |
| p4d = p4d_offset(pgd, addr); |
| do { |
| next = p4d_addr_end(addr, end); |
| if (p4d_none_or_clear_bad(p4d)) |
| continue; |
| ret = unuse_pud_range(vma, p4d, addr, next, type); |
| if (ret) |
| return ret; |
| } while (p4d++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static int unuse_vma(struct vm_area_struct *vma, unsigned int type) |
| { |
| pgd_t *pgd; |
| unsigned long addr, end, next; |
| int ret; |
| |
| addr = vma->vm_start; |
| end = vma->vm_end; |
| |
| pgd = pgd_offset(vma->vm_mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none_or_clear_bad(pgd)) |
| continue; |
| ret = unuse_p4d_range(vma, pgd, addr, next, type); |
| if (ret) |
| return ret; |
| } while (pgd++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static int unuse_mm(struct mm_struct *mm, unsigned int type) |
| { |
| struct vm_area_struct *vma; |
| int ret = 0; |
| VMA_ITERATOR(vmi, mm, 0); |
| |
| mmap_read_lock(mm); |
| for_each_vma(vmi, vma) { |
| if (vma->anon_vma && !is_vm_hugetlb_page(vma)) { |
| ret = unuse_vma(vma, type); |
| if (ret) |
| break; |
| } |
| |
| cond_resched(); |
| } |
| mmap_read_unlock(mm); |
| return ret; |
| } |
| |
| /* |
| * Scan swap_map from current position to next entry still in use. |
| * Return 0 if there are no inuse entries after prev till end of |
| * the map. |
| */ |
| static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
| unsigned int prev) |
| { |
| unsigned int i; |
| unsigned char count; |
| |
| /* |
| * No need for swap_lock here: we're just looking |
| * for whether an entry is in use, not modifying it; false |
| * hits are okay, and sys_swapoff() has already prevented new |
| * allocations from this area (while holding swap_lock). |
| */ |
| for (i = prev + 1; i < si->max; i++) { |
| count = READ_ONCE(si->swap_map[i]); |
| if (count && swap_count(count) != SWAP_MAP_BAD) |
| break; |
| if ((i % LATENCY_LIMIT) == 0) |
| cond_resched(); |
| } |
| |
| if (i == si->max) |
| i = 0; |
| |
| return i; |
| } |
| |
| static int try_to_unuse(unsigned int type) |
| { |
| struct mm_struct *prev_mm; |
| struct mm_struct *mm; |
| struct list_head *p; |
| int retval = 0; |
| struct swap_info_struct *si = swap_info[type]; |
| struct folio *folio; |
| swp_entry_t entry; |
| unsigned int i; |
| |
| if (!READ_ONCE(si->inuse_pages)) |
| goto success; |
| |
| retry: |
| retval = shmem_unuse(type); |
| if (retval) |
| return retval; |
| |
| prev_mm = &init_mm; |
| mmget(prev_mm); |
| |
| spin_lock(&mmlist_lock); |
| p = &init_mm.mmlist; |
| while (READ_ONCE(si->inuse_pages) && |
| !signal_pending(current) && |
| (p = p->next) != &init_mm.mmlist) { |
| |
| mm = list_entry(p, struct mm_struct, mmlist); |
| if (!mmget_not_zero(mm)) |
| continue; |
| spin_unlock(&mmlist_lock); |
| mmput(prev_mm); |
| prev_mm = mm; |
| retval = unuse_mm(mm, type); |
| if (retval) { |
| mmput(prev_mm); |
| return retval; |
| } |
| |
| /* |
| * Make sure that we aren't completely killing |
| * interactive performance. |
| */ |
| cond_resched(); |
| spin_lock(&mmlist_lock); |
| } |
| spin_unlock(&mmlist_lock); |
| |
| mmput(prev_mm); |
| |
| i = 0; |
| while (READ_ONCE(si->inuse_pages) && |
| !signal_pending(current) && |
| (i = find_next_to_unuse(si, i)) != 0) { |
| |
| entry = swp_entry(type, i); |
| folio = filemap_get_folio(swap_address_space(entry), swap_cache_index(entry)); |
| if (IS_ERR(folio)) |
| continue; |
| |
| /* |
| * It is conceivable that a racing task removed this folio from |
| * swap cache just before we acquired the page lock. The folio |
| * might even be back in swap cache on another swap area. But |
| * that is okay, folio_free_swap() only removes stale folios. |
| */ |
| folio_lock(folio); |
| folio_wait_writeback(folio); |
| folio_free_swap(folio); |
| folio_unlock(folio); |
| folio_put(folio); |
| } |
| |
| /* |
| * Lets check again to see if there are still swap entries in the map. |
| * If yes, we would need to do retry the unuse logic again. |
| * Under global memory pressure, swap entries can be reinserted back |
| * into process space after the mmlist loop above passes over them. |
| * |
| * Limit the number of retries? No: when mmget_not_zero() |
| * above fails, that mm is likely to be freeing swap from |
| * exit_mmap(), which proceeds at its own independent pace; |
| * and even shmem_writepage() could have been preempted after |
| * folio_alloc_swap(), temporarily hiding that swap. It's easy |
| * and robust (though cpu-intensive) just to keep retrying. |
| */ |
| if (READ_ONCE(si->inuse_pages)) { |
| if (!signal_pending(current)) |
| goto retry; |
| return -EINTR; |
| } |
| |
| success: |
| /* |
| * Make sure that further cleanups after try_to_unuse() returns happen |
| * after swap_range_free() reduces si->inuse_pages to 0. |
| */ |
| smp_mb(); |
| return 0; |
| } |
| |
| /* |
| * After a successful try_to_unuse, if no swap is now in use, we know |
| * we can empty the mmlist. swap_lock must be held on entry and exit. |
| * Note that mmlist_lock nests inside swap_lock, and an mm must be |
| * added to the mmlist just after page_duplicate - before would be racy. |
| */ |
| static void drain_mmlist(void) |
| { |
| struct list_head *p, *next; |
| unsigned int type; |
| |
| for (type = 0; type < nr_swapfiles; type++) |
| if (swap_info[type]->inuse_pages) |
| return; |
| spin_lock(&mmlist_lock); |
| list_for_each_safe(p, next, &init_mm.mmlist) |
| list_del_init(p); |
| spin_unlock(&mmlist_lock); |
| } |
| |
| /* |
| * Free all of a swapdev's extent information |
| */ |
| static void destroy_swap_extents(struct swap_info_struct *sis) |
| { |
| while (!RB_EMPTY_ROOT(&sis->swap_extent_root)) { |
| struct rb_node *rb = sis->swap_extent_root.rb_node; |
| struct swap_extent *se = rb_entry(rb, struct swap_extent, rb_node); |
| |
| rb_erase(rb, &sis->swap_extent_root); |
| kfree(se); |
| } |
| |
| if (sis->flags & SWP_ACTIVATED) { |
| struct file *swap_file = sis->swap_file; |
| struct address_space *mapping = swap_file->f_mapping; |
| |
| sis->flags &= ~SWP_ACTIVATED; |
| if (mapping->a_ops->swap_deactivate) |
| mapping->a_ops->swap_deactivate(swap_file); |
| } |
| } |
| |
| /* |
| * Add a block range (and the corresponding page range) into this swapdev's |
| * extent tree. |
| * |
| * This function rather assumes that it is called in ascending page order. |
| */ |
| int |
| add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, |
| unsigned long nr_pages, sector_t start_block) |
| { |
| struct rb_node **link = &sis->swap_extent_root.rb_node, *parent = NULL; |
| struct swap_extent *se; |
| struct swap_extent *new_se; |
| |
| /* |
| * place the new node at the right most since the |
| * function is called in ascending page order. |
| */ |
| while (*link) { |
| parent = *link; |
| link = &parent->rb_right; |
| } |
| |
| if (parent) { |
| se = rb_entry(parent, struct swap_extent, rb_node); |
| BUG_ON(se->start_page + se->nr_pages != start_page); |
| if (se->start_block + se->nr_pages == start_block) { |
| /* Merge it */ |
| se->nr_pages += nr_pages; |
| return 0; |
| } |
| } |
| |
| /* No merge, insert a new extent. */ |
| new_se = kmalloc(sizeof(*se), GFP_KERNEL); |
| if (new_se == NULL) |
| return -ENOMEM; |
| new_se->start_page = start_page; |
| new_se->nr_pages = nr_pages; |
| new_se->start_block = start_block; |
| |
| rb_link_node(&new_se->rb_node, parent, link); |
| rb_insert_color(&new_se->rb_node, &sis->swap_extent_root); |
| return 1; |
| } |
| EXPORT_SYMBOL_GPL(add_swap_extent); |
| |
| /* |
| * A `swap extent' is a simple thing which maps a contiguous range of pages |
| * onto a contiguous range of disk blocks. A rbtree of swap extents is |
| * built at swapon time and is then used at swap_writepage/swap_read_folio |
| * time for locating where on disk a page belongs. |
| * |
| * If the swapfile is an S_ISBLK block device, a single extent is installed. |
| * This is done so that the main operating code can treat S_ISBLK and S_ISREG |
| * swap files identically. |
| * |
| * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap |
| * extent rbtree operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK |
| * swapfiles are handled *identically* after swapon time. |
| * |
| * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks |
| * and will parse them into a rbtree, in PAGE_SIZE chunks. If some stray |
| * blocks are found which do not fall within the PAGE_SIZE alignment |
| * requirements, they are simply tossed out - we will never use those blocks |
| * for swapping. |
| * |
| * For all swap devices we set S_SWAPFILE across the life of the swapon. This |
| * prevents users from writing to the swap device, which will corrupt memory. |
| * |
| * The amount of disk space which a single swap extent represents varies. |
| * Typically it is in the 1-4 megabyte range. So we can have hundreds of |
| * extents in the rbtree. - akpm. |
| */ |
| static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
| { |
| struct file *swap_file = sis->swap_file; |
| struct address_space *mapping = swap_file->f_mapping; |
| struct inode *inode = mapping->host; |
| int ret; |
| |
| if (S_ISBLK(inode->i_mode)) { |
| ret = add_swap_extent(sis, 0, sis->max, 0); |
| *span = sis->pages; |
| return ret; |
| } |
| |
| if (mapping->a_ops->swap_activate) { |
| ret = mapping->a_ops->swap_activate(sis, swap_file, span); |
| if (ret < 0) |
| return ret; |
| sis->flags |= SWP_ACTIVATED; |
| if ((sis->flags & SWP_FS_OPS) && |
| sio_pool_init() != 0) { |
| destroy_swap_extents(sis); |
| return -ENOMEM; |
| } |
| return ret; |
| } |
| |
| return generic_swapfile_activate(sis, swap_file, span); |
| } |
| |
| static int swap_node(struct swap_info_struct *si) |
| { |
| struct block_device *bdev; |
| |
| if (si->bdev) |
| bdev = si->bdev; |
| else |
| bdev = si->swap_file->f_inode->i_sb->s_bdev; |
| |
| return bdev ? bdev->bd_disk->node_id : NUMA_NO_NODE; |
| } |
| |
| static void setup_swap_info(struct swap_info_struct *si, int prio, |
| unsigned char *swap_map, |
| struct swap_cluster_info *cluster_info, |
| unsigned long *zeromap) |
| { |
| int i; |
| |
| if (prio >= 0) |
| si->prio = prio; |
| else |
| si->prio = --least_priority; |
| /* |
| * the plist prio is negated because plist ordering is |
| * low-to-high, while swap ordering is high-to-low |
| */ |
| si->list.prio = -si->prio; |
| for_each_node(i) { |
| if (si->prio >= 0) |
| si->avail_lists[i].prio = -si->prio; |
| else { |
| if (swap_node(si) == i) |
| si->avail_lists[i].prio = 1; |
| else |
| si->avail_lists[i].prio = -si->prio; |
| } |
| } |
| si->swap_map = swap_map; |
| si->cluster_info = cluster_info; |
| si->zeromap = zeromap; |
| } |
| |
| static void _enable_swap_info(struct swap_info_struct *si) |
| { |
| si->flags |= SWP_WRITEOK; |
| atomic_long_add(si->pages, &nr_swap_pages); |
| total_swap_pages += si->pages; |
| |
| assert_spin_locked(&swap_lock); |
| /* |
| * both lists are plists, and thus priority ordered. |
| * swap_active_head needs to be priority ordered for swapoff(), |
| * which on removal of any swap_info_struct with an auto-assigned |
| * (i.e. negative) priority increments the auto-assigned priority |
| * of any lower-priority swap_info_structs. |
| * swap_avail_head needs to be priority ordered for folio_alloc_swap(), |
| * which allocates swap pages from the highest available priority |
| * swap_info_struct. |
| */ |
| plist_add(&si->list, &swap_active_head); |
| |
| /* add to available list iff swap device is not full */ |
| if (si->highest_bit) |
| add_to_avail_list(si); |
| } |
| |
| static void enable_swap_info(struct swap_info_struct *si, int prio, |
| unsigned char *swap_map, |
| struct swap_cluster_info *cluster_info, |
| unsigned long *zeromap) |
| { |
| spin_lock(&swap_lock); |
| spin_lock(&si->lock); |
| setup_swap_info(si, prio, swap_map, cluster_info, zeromap); |
| spin_unlock(&si->lock); |
| spin_unlock(&swap_lock); |
| /* |
| * Finished initializing swap device, now it's safe to reference it. |
| */ |
| percpu_ref_resurrect(&si->users); |
| spin_lock(&swap_lock); |
| spin_lock(&si->lock); |
| _enable_swap_info(si); |
| spin_unlock(&si->lock); |
| spin_unlock(&swap_lock); |
| } |
| |
| static void reinsert_swap_info(struct swap_info_struct *si) |
| { |
| spin_lock(&swap_lock); |
| spin_lock(&si->lock); |
| setup_swap_info(si, si->prio, si->swap_map, si->cluster_info, si->zeromap); |
| _enable_swap_info(si); |
| spin_unlock(&si->lock); |
| spin_unlock(&swap_lock); |
| } |
| |
| static bool __has_usable_swap(void) |
| { |
| return !plist_head_empty(&swap_active_head); |
| } |
| |
| bool has_usable_swap(void) |
| { |
| bool ret; |
| |
| spin_lock(&swap_lock); |
| ret = __has_usable_swap(); |
| spin_unlock(&swap_lock); |
| return ret; |
| } |
| |
| SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
| { |
| struct swap_info_struct *p = NULL; |
| unsigned char *swap_map; |
| unsigned long *zeromap; |
| struct swap_cluster_info *cluster_info; |
| struct file *swap_file, *victim; |
| struct address_space *mapping; |
| struct inode *inode; |
| struct filename *pathname; |
| int err, found = 0; |
| |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| |
| BUG_ON(!current->mm); |
| |
| pathname = getname(specialfile); |
| if (IS_ERR(pathname)) |
| return PTR_ERR(pathname); |
| |
| victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0); |
| err = PTR_ERR(victim); |
| if (IS_ERR(victim)) |
| goto out; |
| |
| mapping = victim->f_mapping; |
| spin_lock(&swap_lock); |
| plist_for_each_entry(p, &swap_active_head, list) { |
| if (p->flags & SWP_WRITEOK) { |
| if (p->swap_file->f_mapping == mapping) { |
| found = 1; |
| break; |
| } |
| } |
| } |
| if (!found) { |
| err = -EINVAL; |
| spin_unlock(&swap_lock); |
| goto out_dput; |
| } |
| if (!security_vm_enough_memory_mm(current->mm, p->pages)) |
| vm_unacct_memory(p->pages); |
| else { |
| err = -ENOMEM; |
| spin_unlock(&swap_lock); |
| goto out_dput; |
| } |
| spin_lock(&p->lock); |
| del_from_avail_list(p); |
| if (p->prio < 0) { |
| struct swap_info_struct *si = p; |
| int nid; |
| |
| plist_for_each_entry_continue(si, &swap_active_head, list) { |
| si->prio++; |
| si->list.prio--; |
| for_each_node(nid) { |
| if (si->avail_lists[nid].prio != 1) |
| si->avail_lists[nid].prio--; |
| } |
| } |
| least_priority++; |
| } |
| plist_del(&p->list, &swap_active_head); |
| atomic_long_sub(p->pages, &nr_swap_pages); |
| total_swap_pages -= p->pages; |
| p->flags &= ~SWP_WRITEOK; |
| spin_unlock(&p->lock); |
| spin_unlock(&swap_lock); |
| |
| disable_swap_slots_cache_lock(); |
| |
| set_current_oom_origin(); |
| err = try_to_unuse(p->type); |
| clear_current_oom_origin(); |
| |
| if (err) { |
| /* re-insert swap space back into swap_list */ |
| reinsert_swap_info(p); |
| reenable_swap_slots_cache_unlock(); |
| goto out_dput; |
| } |
| |
| reenable_swap_slots_cache_unlock(); |
| |
| /* |
| * Wait for swap operations protected by get/put_swap_device() |
| * to complete. Because of synchronize_rcu() here, all swap |
| * operations protected by RCU reader side lock (including any |
| * spinlock) will be waited too. This makes it easy to |
| * prevent folio_test_swapcache() and the following swap cache |
| * operations from racing with swapoff. |
| */ |
| percpu_ref_kill(&p->users); |
| synchronize_rcu(); |
| wait_for_completion(&p->comp); |
| |
| flush_work(&p->discard_work); |
| |
| destroy_swap_extents(p); |
| if (p->flags & SWP_CONTINUED) |
| free_swap_count_continuations(p); |
| |
| if (!p->bdev || !bdev_nonrot(p->bdev)) |
| atomic_dec(&nr_rotate_swap); |
| |
| mutex_lock(&swapon_mutex); |
| spin_lock(&swap_lock); |
| spin_lock(&p->lock); |
| drain_mmlist(); |
| |
| /* wait for anyone still in scan_swap_map_slots */ |
| p->highest_bit = 0; /* cuts scans short */ |
| while (p->flags >= SWP_SCANNING) { |
| spin_unlock(&p->lock); |
| spin_unlock(&swap_lock); |
| schedule_timeout_uninterruptible(1); |
| spin_lock(&swap_lock); |
| spin_lock(&p->lock); |
| } |
| |
| swap_file = p->swap_file; |
| p->swap_file = NULL; |
| p->max = 0; |
| swap_map = p->swap_map; |
| p->swap_map = NULL; |
| zeromap = p->zeromap; |
| p->zeromap = NULL; |
| cluster_info = p->cluster_info; |
| p->cluster_info = NULL; |
| spin_unlock(&p->lock); |
| spin_unlock(&swap_lock); |
| arch_swap_invalidate_area(p->type); |
| zswap_swapoff(p->type); |
| mutex_unlock(&swapon_mutex); |
| free_percpu(p->percpu_cluster); |
| p->percpu_cluster = NULL; |
| free_percpu(p->cluster_next_cpu); |
| p->cluster_next_cpu = NULL; |
| vfree(swap_map); |
| kvfree(zeromap); |
| kvfree(cluster_info); |
| /* Destroy swap account information */ |
| swap_cgroup_swapoff(p->type); |
| exit_swap_address_space(p->type); |
| |
| inode = mapping->host; |
| |
| inode_lock(inode); |
| inode->i_flags &= ~S_SWAPFILE; |
| inode_unlock(inode); |
| filp_close(swap_file, NULL); |
| |
| /* |
| * Clear the SWP_USED flag after all resources are freed so that swapon |
| * can reuse this swap_info in alloc_swap_info() safely. It is ok to |
| * not hold p->lock after we cleared its SWP_WRITEOK. |
| */ |
| spin_lock(&swap_lock); |
| p->flags = 0; |
| spin_unlock(&swap_lock); |
| |
| err = 0; |
| atomic_inc(&proc_poll_event); |
| wake_up_interruptible(&proc_poll_wait); |
| |
| out_dput: |
| filp_close(victim, NULL); |
| out: |
| putname(pathname); |
| return err; |
| } |
| |
| #ifdef CONFIG_PROC_FS |
| static __poll_t swaps_poll(struct file *file, poll_table *wait) |
| { |
| struct seq_file *seq = file->private_data; |
| |
| poll_wait(file, &proc_poll_wait, wait); |
| |
| if (seq->poll_event != atomic_read(&proc_poll_event)) { |
| seq->poll_event = atomic_read(&proc_poll_event); |
| return EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI; |
| } |
| |
| return EPOLLIN | EPOLLRDNORM; |
| } |
| |
| /* iterator */ |
| static void *swap_start(struct seq_file *swap, loff_t *pos) |
| { |
| struct swap_info_struct *si; |
| int type; |
| loff_t l = *pos; |
| |
| mutex_lock(&swapon_mutex); |
| |
| if (!l) |
| return SEQ_START_TOKEN; |
| |
| for (type = 0; (si = swap_type_to_swap_info(type)); type++) { |
| if (!(si->flags & SWP_USED) || !si->swap_map) |
| continue; |
| if (!--l) |
| return si; |
| } |
| |
| return NULL; |
| } |
| |
| static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) |
| { |
| struct swap_info_struct *si = v; |
| int type; |
| |
| if (v == SEQ_START_TOKEN) |
| type = 0; |
| else |
| type = si->type + 1; |
| |
| ++(*pos); |
| for (; (si = swap_type_to_swap_info(type)); type++) { |
| if (!(si->flags & SWP_USED) || !si->swap_map) |
| continue; |
| return si; |
| } |
| |
| return NULL; |
| } |
| |
| static void swap_stop(struct seq_file *swap, void *v) |
| { |
| mutex_unlock(&swapon_mutex); |
| } |
| |
| static int swap_show(struct seq_file *swap, void *v) |
| { |
| struct swap_info_struct *si = v; |
| struct file *file; |
| int len; |
| unsigned long bytes, inuse; |
| |
| if (si == SEQ_START_TOKEN) { |
| seq_puts(swap, "Filename\t\t\t\tType\t\tSize\t\tUsed\t\tPriority\n"); |
| return 0; |
| } |
| |
| bytes = K(si->pages); |
| inuse = K(READ_ONCE(si->inuse_pages)); |
| |
| file = si->swap_file; |
| len = seq_file_path(swap, file, " \t\n\\"); |
| seq_printf(swap, "%*s%s\t%lu\t%s%lu\t%s%d\n", |
| len < 40 ? 40 - len : 1, " ", |
| S_ISBLK(file_inode(file)->i_mode) ? |
| "partition" : "file\t", |
| bytes, bytes < 10000000 ? "\t" : "", |
| inuse, inuse < 10000000 ? "\t" : "", |
| si->prio); |
| return 0; |
| } |
| |
| static const struct seq_operations swaps_op = { |
| .start = swap_start, |
| .next = swap_next, |
| .stop = swap_stop, |
| .show = swap_show |
| }; |
| |
| static int swaps_open(struct inode *inode, struct file *file) |
| { |
| struct seq_file *seq; |
| int ret; |
| |
| ret = seq_open(file, &swaps_op); |
| if (ret) |
| return ret; |
| |
| seq = file->private_data; |
| seq->poll_event = atomic_read(&proc_poll_event); |
| return 0; |
| } |
| |
| static const struct proc_ops swaps_proc_ops = { |
| .proc_flags = PROC_ENTRY_PERMANENT, |
| .proc_open = swaps_open, |
| .proc_read = seq_read, |
| .proc_lseek = seq_lseek, |
| .proc_release = seq_release, |
| .proc_poll = swaps_poll, |
| }; |
| |
| static int __init procswaps_init(void) |
| { |
| proc_create("swaps", 0, NULL, &swaps_proc_ops); |
| return 0; |
| } |
| __initcall(procswaps_init); |
| #endif /* CONFIG_PROC_FS */ |
| |
| #ifdef MAX_SWAPFILES_CHECK |
| static int __init max_swapfiles_check(void) |
| { |
| MAX_SWAPFILES_CHECK(); |
| return 0; |
| } |
| late_initcall(max_swapfiles_check); |
| #endif |
| |
| static struct swap_info_struct *alloc_swap_info(void) |
| { |
| struct swap_info_struct *p; |
| struct swap_info_struct *defer = NULL; |
| unsigned int type; |
| int i; |
| |
| p = kvzalloc(struct_size(p, avail_lists, nr_node_ids), GFP_KERNEL); |
| if (!p) |
| return ERR_PTR(-ENOMEM); |
| |
| if (percpu_ref_init(&p->users, swap_users_ref_free, |
| PERCPU_REF_INIT_DEAD, GFP_KERNEL)) { |
| kvfree(p); |
| return ERR_PTR(-ENOMEM); |
| } |
| |
| spin_lock(&swap_lock); |
| for (type = 0; type < nr_swapfiles; type++) { |
| if (!(swap_info[type]->flags & SWP_USED)) |
| break; |
| } |
| if (type >= MAX_SWAPFILES) { |
| spin_unlock(&swap_lock); |
| percpu_ref_exit(&p->users); |
| kvfree(p); |
| return ERR_PTR(-EPERM); |
| } |
| if (type >= nr_swapfiles) { |
| p->type = type; |
| /* |
| * Publish the swap_info_struct after initializing it. |
| * Note that kvzalloc() above zeroes all its fields. |
| */ |
| smp_store_release(&swap_info[type], p); /* rcu_assign_pointer() */ |
| nr_swapfiles++; |
| } else { |
| defer = p; |
| p = swap_info[type]; |
| /* |
| * Do not memset this entry: a racing procfs swap_next() |
| * would be relying on p->type to remain valid. |
| */ |
| } |
| p->swap_extent_root = RB_ROOT; |
| plist_node_init(&p->list, 0); |
| for_each_node(i) |
| plist_node_init(&p->avail_lists[i], 0); |
| p->flags = SWP_USED; |
| spin_unlock(&swap_lock); |
| if (defer) { |
| percpu_ref_exit(&defer->users); |
| kvfree(defer); |
| } |
| spin_lock_init(&p->lock); |
| spin_lock_init(&p->cont_lock); |
| init_completion(&p->comp); |
| |
| return p; |
| } |
| |
| static int claim_swapfile(struct swap_info_struct *si, struct inode *inode) |
| { |
| if (S_ISBLK(inode->i_mode)) { |
| si->bdev = I_BDEV(inode); |
| /* |
| * Zoned block devices contain zones that have a sequential |
| * write only restriction. Hence zoned block devices are not |
| * suitable for swapping. Disallow them here. |
| */ |
| if (bdev_is_zoned(si->bdev)) |
| return -EINVAL; |
| si->flags |= SWP_BLKDEV; |
| } else if (S_ISREG(inode->i_mode)) { |
| si->bdev = inode->i_sb->s_bdev; |
| } |
| |
| return 0; |
| } |
| |
| |
| /* |
| * Find out how many pages are allowed for a single swap device. There |
| * are two limiting factors: |
| * 1) the number of bits for the swap offset in the swp_entry_t type, and |
| * 2) the number of bits in the swap pte, as defined by the different |
| * architectures. |
| * |
| * In order to find the largest possible bit mask, a swap entry with |
| * swap type 0 and swap offset ~0UL is created, encoded to a swap pte, |
| * decoded to a swp_entry_t again, and finally the swap offset is |
| * extracted. |
| * |
| * This will mask all the bits from the initial ~0UL mask that can't |
| * be encoded in either the swp_entry_t or the architecture definition |
| * of a swap pte. |
| */ |
|