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- // 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/frontswap.h>
- #include <linux/swapfile.h>
- #include <linux/export.h>
- #include <linux/swap_slots.h>
- #include <linux/sort.h>
- #include <linux/completion.h>
- #include <asm/tlbflush.h>
- #include <linux/swapops.h>
- #include <linux/swap_cgroup.h>
- #include "swap.h"
- #include <trace/hooks/bl_hib.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 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);
- 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
- /* returns 1 if swap entry is freed */
- 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 folio *folio;
- int ret = 0;
- folio = filemap_get_folio(swap_address_space(entry), offset);
- if (!folio)
- return 0;
- /*
- * 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)) {
- if ((flags & TTRS_ANYWAY) ||
- ((flags & TTRS_UNMAPPED) && !folio_mapped(folio)) ||
- ((flags & TTRS_FULL) && mem_cgroup_swap_full(folio)))
- ret = folio_free_swap(folio);
- folio_unlock(folio);
- }
- 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_page_sector(struct page *page)
- {
- struct swap_info_struct *sis = page_swap_info(page);
- struct swap_extent *se;
- sector_t sector;
- pgoff_t offset;
- offset = __page_file_index(page);
- 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_size(size) (size)
- #else
- #define SWAPFILE_CLUSTER 256
- /*
- * Define swap_entry_size() as constant to let compiler to optimize
- * out some code if !CONFIG_THP_SWAP
- */
- #define swap_entry_size(size) 1
- #endif
- #define LATENCY_LIMIT 256
- static inline void cluster_set_flag(struct swap_cluster_info *info,
- unsigned int flag)
- {
- info->flags = flag;
- }
- static inline unsigned int cluster_count(struct swap_cluster_info *info)
- {
- return info->data;
- }
- static inline void cluster_set_count(struct swap_cluster_info *info,
- unsigned int c)
- {
- info->data = c;
- }
- static inline void cluster_set_count_flag(struct swap_cluster_info *info,
- unsigned int c, unsigned int f)
- {
- info->flags = f;
- info->data = c;
- }
- static inline unsigned int cluster_next(struct swap_cluster_info *info)
- {
- return info->data;
- }
- static inline void cluster_set_next(struct swap_cluster_info *info,
- unsigned int n)
- {
- info->data = n;
- }
- static inline void cluster_set_next_flag(struct swap_cluster_info *info,
- unsigned int n, unsigned int f)
- {
- info->flags = f;
- info->data = n;
- }
- static inline bool cluster_is_free(struct swap_cluster_info *info)
- {
- return info->flags & CLUSTER_FLAG_FREE;
- }
- static inline bool cluster_is_null(struct swap_cluster_info *info)
- {
- return info->flags & CLUSTER_FLAG_NEXT_NULL;
- }
- static inline void cluster_set_null(struct swap_cluster_info *info)
- {
- info->flags = CLUSTER_FLAG_NEXT_NULL;
- info->data = 0;
- }
- static inline bool cluster_is_huge(struct swap_cluster_info *info)
- {
- if (IS_ENABLED(CONFIG_THP_SWAP))
- return info->flags & CLUSTER_FLAG_HUGE;
- return false;
- }
- static inline void cluster_clear_huge(struct swap_cluster_info *info)
- {
- info->flags &= ~CLUSTER_FLAG_HUGE;
- }
- 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);
- }
- static inline bool cluster_list_empty(struct swap_cluster_list *list)
- {
- return cluster_is_null(&list->head);
- }
- static inline unsigned int cluster_list_first(struct swap_cluster_list *list)
- {
- return cluster_next(&list->head);
- }
- static void cluster_list_init(struct swap_cluster_list *list)
- {
- cluster_set_null(&list->head);
- cluster_set_null(&list->tail);
- }
- static void cluster_list_add_tail(struct swap_cluster_list *list,
- struct swap_cluster_info *ci,
- unsigned int idx)
- {
- if (cluster_list_empty(list)) {
- cluster_set_next_flag(&list->head, idx, 0);
- cluster_set_next_flag(&list->tail, idx, 0);
- } else {
- struct swap_cluster_info *ci_tail;
- unsigned int tail = cluster_next(&list->tail);
- /*
- * Nested cluster lock, but both cluster locks are
- * only acquired when we held swap_info_struct->lock
- */
- ci_tail = ci + tail;
- spin_lock_nested(&ci_tail->lock, SINGLE_DEPTH_NESTING);
- cluster_set_next(ci_tail, idx);
- spin_unlock(&ci_tail->lock);
- cluster_set_next_flag(&list->tail, idx, 0);
- }
- }
- static unsigned int cluster_list_del_first(struct swap_cluster_list *list,
- struct swap_cluster_info *ci)
- {
- unsigned int idx;
- idx = cluster_next(&list->head);
- if (cluster_next(&list->tail) == idx) {
- cluster_set_null(&list->head);
- cluster_set_null(&list->tail);
- } else
- cluster_set_next_flag(&list->head,
- cluster_next(&ci[idx]), 0);
- return idx;
- }
- /* Add a cluster to discard list and schedule it to do discard */
- static void swap_cluster_schedule_discard(struct swap_info_struct *si,
- unsigned int idx)
- {
- /*
- * 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);
- cluster_list_add_tail(&si->discard_clusters, si->cluster_info, idx);
- schedule_work(&si->discard_work);
- }
- static void __free_cluster(struct swap_info_struct *si, unsigned long idx)
- {
- struct swap_cluster_info *ci = si->cluster_info;
- cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE);
- cluster_list_add_tail(&si->free_clusters, ci, idx);
- }
- /*
- * 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 *info, *ci;
- unsigned int idx;
- info = si->cluster_info;
- while (!cluster_list_empty(&si->discard_clusters)) {
- idx = cluster_list_del_first(&si->discard_clusters, info);
- spin_unlock(&si->lock);
- discard_swap_cluster(si, idx * SWAPFILE_CLUSTER,
- SWAPFILE_CLUSTER);
- spin_lock(&si->lock);
- ci = lock_cluster(si, idx * SWAPFILE_CLUSTER);
- __free_cluster(si, idx);
- memset(si->swap_map + idx * SWAPFILE_CLUSTER,
- 0, SWAPFILE_CLUSTER);
- unlock_cluster(ci);
- }
- }
- 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 alloc_cluster(struct swap_info_struct *si, unsigned long idx)
- {
- struct swap_cluster_info *ci = si->cluster_info;
- VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx);
- cluster_list_del_first(&si->free_clusters, ci);
- cluster_set_count_flag(ci + idx, 0, 0);
- }
- static void free_cluster(struct swap_info_struct *si, unsigned long idx)
- {
- struct swap_cluster_info *ci = si->cluster_info + idx;
- VM_BUG_ON(cluster_count(ci) != 0);
- /*
- * 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, idx);
- return;
- }
- __free_cluster(si, idx);
- }
- /*
- * The cluster corresponding to page_nr will be used. The cluster will be
- * removed from free cluster list and its usage counter will be increased.
- */
- static void inc_cluster_info_page(struct swap_info_struct *p,
- struct swap_cluster_info *cluster_info, unsigned long page_nr)
- {
- unsigned long idx = page_nr / SWAPFILE_CLUSTER;
- if (!cluster_info)
- return;
- if (cluster_is_free(&cluster_info[idx]))
- alloc_cluster(p, idx);
- VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER);
- cluster_set_count(&cluster_info[idx],
- cluster_count(&cluster_info[idx]) + 1);
- }
- /*
- * The cluster corresponding to page_nr decreases one usage. If the usage
- * counter becomes 0, which means no page in the cluster is in using, we can
- * optionally discard the cluster and add it to free cluster list.
- */
- static void dec_cluster_info_page(struct swap_info_struct *p,
- struct swap_cluster_info *cluster_info, unsigned long page_nr)
- {
- unsigned long idx = page_nr / SWAPFILE_CLUSTER;
- if (!cluster_info)
- return;
- VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0);
- cluster_set_count(&cluster_info[idx],
- cluster_count(&cluster_info[idx]) - 1);
- if (cluster_count(&cluster_info[idx]) == 0)
- free_cluster(p, idx);
- }
- /*
- * It's possible scan_swap_map_slots() uses a free cluster in the middle of free
- * cluster list. Avoiding such abuse to avoid list corruption.
- */
- static bool
- scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si,
- unsigned long offset)
- {
- struct percpu_cluster *percpu_cluster;
- bool conflict;
- offset /= SWAPFILE_CLUSTER;
- conflict = !cluster_list_empty(&si->free_clusters) &&
- offset != cluster_list_first(&si->free_clusters) &&
- cluster_is_free(&si->cluster_info[offset]);
- if (!conflict)
- return false;
- percpu_cluster = this_cpu_ptr(si->percpu_cluster);
- cluster_set_null(&percpu_cluster->index);
- return true;
- }
- /*
- * Try to get a swap entry from current cpu's swap entry pool (a cluster). This
- * might involve allocating a new cluster for current CPU too.
- */
- static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si,
- unsigned long *offset, unsigned long *scan_base)
- {
- struct percpu_cluster *cluster;
- struct swap_cluster_info *ci;
- unsigned long tmp, max;
- new_cluster:
- cluster = this_cpu_ptr(si->percpu_cluster);
- if (cluster_is_null(&cluster->index)) {
- if (!cluster_list_empty(&si->free_clusters)) {
- cluster->index = si->free_clusters.head;
- cluster->next = cluster_next(&cluster->index) *
- SWAPFILE_CLUSTER;
- } else if (!cluster_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);
- *scan_base = this_cpu_read(*si->cluster_next_cpu);
- *offset = *scan_base;
- goto new_cluster;
- } else
- return false;
- }
- /*
- * Other CPUs can use our cluster if they can't find a free cluster,
- * check if there is still free entry in the cluster
- */
- tmp = cluster->next;
- max = min_t(unsigned long, si->max,
- (cluster_next(&cluster->index) + 1) * SWAPFILE_CLUSTER);
- if (tmp < max) {
- ci = lock_cluster(si, tmp);
- while (tmp < max) {
- if (!si->swap_map[tmp])
- break;
- tmp++;
- }
- unlock_cluster(ci);
- }
- if (tmp >= max) {
- cluster_set_null(&cluster->index);
- goto new_cluster;
- }
- cluster->next = tmp + 1;
- *offset = tmp;
- *scan_base = tmp;
- return true;
- }
- static void __del_from_avail_list(struct swap_info_struct *p)
- {
- int nid;
- assert_spin_locked(&p->lock);
- for_each_node(nid)
- plist_del(&p->avail_lists[nid], &swap_avail_heads[nid]);
- }
- static void del_from_avail_list(struct swap_info_struct *p)
- {
- spin_lock(&swap_avail_lock);
- __del_from_avail_list(p);
- 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 *p)
- {
- int nid;
- spin_lock(&swap_avail_lock);
- for_each_node(nid) {
- WARN_ON(!plist_node_empty(&p->avail_lists[nid]));
- plist_add(&p->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);
- 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);
- }
- atomic_long_add(nr_entries, &nr_swap_pages);
- WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries);
- 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);
- frontswap_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);
- }
- 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 = si->lowest_bit +
- prandom_u32_max(si->highest_bit - si->lowest_bit + 1);
- 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 scan_swap_map_slots(struct swap_info_struct *si,
- unsigned char usage, int nr,
- swp_entry_t slots[])
- {
- struct swap_cluster_info *ci;
- unsigned long offset;
- unsigned long scan_base;
- unsigned long last_in_cluster = 0;
- int latency_ration = LATENCY_LIMIT;
- 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
- */
- si->flags += SWP_SCANNING;
- /*
- * Use percpu scan base for SSD to reduce lock contention on
- * cluster and swap cache. For HDD, sequential access is more
- * important.
- */
- if (si->flags & SWP_SOLIDSTATE)
- scan_base = this_cpu_read(*si->cluster_next_cpu);
- else
- scan_base = si->cluster_next;
- offset = scan_base;
- /* SSD algorithm */
- if (si->cluster_info) {
- if (!scan_swap_map_try_ssd_cluster(si, &offset, &scan_base))
- goto scan;
- } else 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.
- * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info
- * case, just handled by scan_swap_map_try_ssd_cluster() above.
- */
- scan_base = offset = si->lowest_bit;
- last_in_cluster = offset + SWAPFILE_CLUSTER - 1;
- /* Locate the first empty (unaligned) cluster */
- for (; last_in_cluster <= 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->cluster_info) {
- while (scan_swap_map_ssd_cluster_conflict(si, offset)) {
- /* take a break if we already got some slots */
- if (n_ret)
- goto done;
- if (!scan_swap_map_try_ssd_cluster(si, &offset,
- &scan_base))
- goto scan;
- }
- }
- 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;
- ci = lock_cluster(si, offset);
- /* 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;
- unlock_cluster(ci);
- spin_unlock(&si->lock);
- swap_was_freed = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY);
- spin_lock(&si->lock);
- /* entry was freed successfully, try to use this again */
- if (swap_was_freed)
- goto checks;
- goto scan; /* check next one */
- }
- if (si->swap_map[offset]) {
- unlock_cluster(ci);
- if (!n_ret)
- goto scan;
- else
- goto done;
- }
- WRITE_ONCE(si->swap_map[offset], usage);
- inc_cluster_info_page(si, si->cluster_info, offset);
- unlock_cluster(ci);
- swap_range_alloc(si, offset, 1);
- 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;
- }
- /* try to get more slots in cluster */
- if (si->cluster_info) {
- if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base))
- goto checks;
- } else 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:
- set_cluster_next(si, offset + 1);
- si->flags -= SWP_SCANNING;
- return n_ret;
- scan:
- 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;
- }
- static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot)
- {
- unsigned long idx;
- struct swap_cluster_info *ci;
- unsigned long offset;
- /*
- * Should not even be attempting cluster allocations when huge
- * page swap is disabled. Warn and fail the allocation.
- */
- if (!IS_ENABLED(CONFIG_THP_SWAP)) {
- VM_WARN_ON_ONCE(1);
- return 0;
- }
- if (cluster_list_empty(&si->free_clusters))
- return 0;
- idx = cluster_list_first(&si->free_clusters);
- offset = idx * SWAPFILE_CLUSTER;
- ci = lock_cluster(si, offset);
- alloc_cluster(si, idx);
- cluster_set_count_flag(ci, SWAPFILE_CLUSTER, CLUSTER_FLAG_HUGE);
- memset(si->swap_map + offset, SWAP_HAS_CACHE, SWAPFILE_CLUSTER);
- unlock_cluster(ci);
- swap_range_alloc(si, offset, SWAPFILE_CLUSTER);
- *slot = swp_entry(si->type, offset);
- return 1;
- }
- static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx)
- {
- unsigned long offset = idx * SWAPFILE_CLUSTER;
- struct swap_cluster_info *ci;
- ci = lock_cluster(si, offset);
- memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER);
- cluster_set_count_flag(ci, 0, 0);
- free_cluster(si, idx);
- unlock_cluster(ci);
- swap_range_free(si, offset, SWAPFILE_CLUSTER);
- }
- int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size)
- {
- unsigned long size = swap_entry_size(entry_size);
- struct swap_info_struct *si, *next;
- long avail_pgs;
- int n_ret = 0;
- int node;
- /* Only single cluster request supported */
- WARN_ON_ONCE(n_goal > 1 && size == SWAPFILE_CLUSTER);
- 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;
- }
- if (size == SWAPFILE_CLUSTER) {
- if (si->flags & SWP_BLKDEV)
- n_ret = swap_alloc_cluster(si, swp_entries);
- } else
- n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE,
- n_goal, swp_entries);
- spin_unlock(&si->lock);
- if (n_ret || size == SWAPFILE_CLUSTER)
- goto check_out;
- pr_debug("scan_swap_map of si %d failed to find offset\n",
- si->type);
- 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 *p;
- unsigned long offset;
- if (!entry.val)
- goto out;
- p = swp_swap_info(entry);
- if (!p)
- goto bad_nofile;
- if (data_race(!(p->flags & SWP_USED)))
- goto bad_device;
- offset = swp_offset(entry);
- if (offset >= p->max)
- goto bad_offset;
- if (data_race(!p->swap_map[swp_offset(entry)]))
- goto bad_free;
- return p;
- 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 *p,
- unsigned long offset,
- unsigned char usage)
- {
- unsigned char count;
- unsigned char has_cache;
- count = p->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(p, offset, count))
- count = SWAP_MAP_MAX | COUNT_CONTINUED;
- else
- count = SWAP_MAP_MAX;
- } else
- count--;
- }
- usage = count | has_cache;
- if (usage)
- WRITE_ONCE(p->swap_map[offset], usage);
- else
- WRITE_ONCE(p->swap_map[offset], SWAP_HAS_CACHE);
- return usage;
- }
- /*
- * 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, such as page lock, page table lock, etc. 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 *p,
- swp_entry_t entry)
- {
- struct swap_cluster_info *ci;
- unsigned long offset = swp_offset(entry);
- unsigned char usage;
- ci = lock_cluster_or_swap_info(p, offset);
- usage = __swap_entry_free_locked(p, offset, 1);
- unlock_cluster_or_swap_info(p, ci);
- if (!usage)
- free_swap_slot(entry);
- return usage;
- }
- static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry)
- {
- struct swap_cluster_info *ci;
- unsigned long offset = swp_offset(entry);
- unsigned char count;
- ci = lock_cluster(p, offset);
- count = p->swap_map[offset];
- VM_BUG_ON(count != SWAP_HAS_CACHE);
- p->swap_map[offset] = 0;
- dec_cluster_info_page(p, p->cluster_info, offset);
- unlock_cluster(ci);
- mem_cgroup_uncharge_swap(entry, 1);
- swap_range_free(p, offset, 1);
- }
- /*
- * Caller has made sure that the swap device corresponding to entry
- * is still around or has not been recycled.
- */
- void swap_free(swp_entry_t entry)
- {
- struct swap_info_struct *p;
- p = _swap_info_get(entry);
- if (p)
- __swap_entry_free(p, entry);
- }
- /*
- * 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);
- unsigned long idx = offset / SWAPFILE_CLUSTER;
- struct swap_cluster_info *ci;
- struct swap_info_struct *si;
- unsigned char *map;
- unsigned int i, free_entries = 0;
- unsigned char val;
- int size = swap_entry_size(folio_nr_pages(folio));
- si = _swap_info_get(entry);
- if (!si)
- return;
- ci = lock_cluster_or_swap_info(si, offset);
- if (size == SWAPFILE_CLUSTER) {
- VM_BUG_ON(!cluster_is_huge(ci));
- map = si->swap_map + offset;
- for (i = 0; i < SWAPFILE_CLUSTER; i++) {
- val = map[i];
- VM_BUG_ON(!(val & SWAP_HAS_CACHE));
- if (val == SWAP_HAS_CACHE)
- free_entries++;
- }
- cluster_clear_huge(ci);
- if (free_entries == SWAPFILE_CLUSTER) {
- unlock_cluster_or_swap_info(si, ci);
- spin_lock(&si->lock);
- mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER);
- swap_free_cluster(si, idx);
- spin_unlock(&si->lock);
- return;
- }
- }
- for (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);
- }
- #ifdef CONFIG_THP_SWAP
- int split_swap_cluster(swp_entry_t entry)
- {
- struct swap_info_struct *si;
- struct swap_cluster_info *ci;
- unsigned long offset = swp_offset(entry);
- si = _swap_info_get(entry);
- if (!si)
- return -EBUSY;
- ci = lock_cluster(si, offset);
- cluster_clear_huge(ci);
- unlock_cluster(ci);
- return 0;
- }
- #endif
- 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_free(p, entries[i]);
- prev = p;
- }
- if (p)
- spin_unlock(&p->lock);
- }
- int __swap_count(swp_entry_t entry)
- {
- struct swap_info_struct *si;
- pgoff_t offset = swp_offset(entry);
- int count = 0;
- si = get_swap_device(entry);
- if (si) {
- count = swap_count(si->swap_map[offset]);
- put_swap_device(si);
- }
- return count;
- }
- /*
- * 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.
- */
- static 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 does not give an exact answer when swap count is continued,
- * but does include the high COUNT_CONTINUED flag to allow for that.
- */
- int __swp_swapcount(swp_entry_t entry)
- {
- int count = 0;
- struct swap_info_struct *si;
- si = get_swap_device(entry);
- if (si) {
- count = swap_swapcount(si, entry);
- put_swap_device(si);
- }
- 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 *p;
- struct swap_cluster_info *ci;
- struct page *page;
- pgoff_t offset;
- unsigned char *map;
- p = _swap_info_get(entry);
- if (!p)
- return 0;
- offset = swp_offset(entry);
- ci = lock_cluster_or_swap_info(p, offset);
- count = swap_count(p->swap_map[offset]);
- if (!(count & COUNT_CONTINUED))
- goto out;
- count &= ~COUNT_CONTINUED;
- n = SWAP_MAP_MAX + 1;
- page = vmalloc_to_page(p->swap_map + offset);
- offset &= ~PAGE_MASK;
- VM_BUG_ON(page_private(page) != SWP_CONTINUED);
- do {
- page = list_next_entry(page, lru);
- map = kmap_atomic(page);
- tmp_count = map[offset];
- kunmap_atomic(map);
- count += (tmp_count & ~COUNT_CONTINUED) * n;
- n *= (SWAP_CONT_MAX + 1);
- } while (tmp_count & COUNT_CONTINUED);
- out:
- unlock_cluster_or_swap_info(p, ci);
- return count;
- }
- static bool swap_page_trans_huge_swapped(struct swap_info_struct *si,
- swp_entry_t entry)
- {
- struct swap_cluster_info *ci;
- unsigned char *map = si->swap_map;
- unsigned long roffset = swp_offset(entry);
- unsigned long offset = round_down(roffset, SWAPFILE_CLUSTER);
- int i;
- bool ret = false;
- ci = lock_cluster_or_swap_info(si, offset);
- if (!ci || !cluster_is_huge(ci)) {
- if (swap_count(map[roffset]))
- ret = true;
- goto unlock_out;
- }
- for (i = 0; i < SWAPFILE_CLUSTER; 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_entry(folio);
- 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_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)
- {
- VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
- if (!folio_test_swapcache(folio))
- return false;
- if (folio_test_writeback(folio))
- return false;
- if (folio_swapped(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;
- delete_from_swap_cache(folio);
- folio_set_dirty(folio);
- return true;
- }
- /*
- * Free the swap entry like above, but also try to
- * free the page cache entry if it is the last user.
- */
- int free_swap_and_cache(swp_entry_t entry)
- {
- struct swap_info_struct *p;
- unsigned char count;
- if (non_swap_entry(entry))
- return 1;
- p = _swap_info_get(entry);
- if (p) {
- count = __swap_entry_free(p, entry);
- if (count == SWAP_HAS_CACHE &&
- !swap_page_trans_huge_swapped(p, entry))
- __try_to_reclaim_swap(p, swp_offset(entry),
- TTRS_UNMAPPED | TTRS_FULL);
- }
- return p != NULL;
- }
- #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))
- 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 = folio_file_page(folio, swp_offset(entry));
- struct page *swapcache;
- spinlock_t *ptl;
- pte_t *pte, new_pte;
- int ret = 1;
- swapcache = page;
- page = ksm_might_need_to_copy(page, vma, addr);
- if (unlikely(!page))
- return -ENOMEM;
- pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
- if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) {
- ret = 0;
- goto out;
- }
- if (unlikely(!PageUptodate(page))) {
- pte_t pteval;
- dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
- pteval = swp_entry_to_pte(make_swapin_error_entry(page));
- set_pte_at(vma->vm_mm, addr, pte, pteval);
- swap_free(entry);
- ret = 0;
- goto out;
- }
- /*
- * 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(entry, page_folio(page));
- /* See do_swap_page() */
- BUG_ON(!PageAnon(page) && PageMappedToDisk(page));
- BUG_ON(PageAnon(page) && PageAnonExclusive(page));
- dec_mm_counter(vma->vm_mm, MM_SWAPENTS);
- inc_mm_counter(vma->vm_mm, MM_ANONPAGES);
- get_page(page);
- if (page == swapcache) {
- rmap_t rmap_flags = RMAP_NONE;
- /*
- * See do_swap_page(): PageWriteback() would be problematic.
- * However, we do a wait_on_page_writeback() just before this
- * call and have the page locked.
- */
- VM_BUG_ON_PAGE(PageWriteback(page), page);
- if (pte_swp_exclusive(*pte))
- rmap_flags |= RMAP_EXCLUSIVE;
- page_add_anon_rmap(page, vma, addr, rmap_flags);
- } else { /* ksm created a completely new copy */
- page_add_new_anon_rmap(page, vma, addr);
- lru_cache_add_inactive_or_unevictable(page, vma);
- }
- new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot));
- if (pte_swp_soft_dirty(*pte))
- new_pte = pte_mksoft_dirty(new_pte);
- if (pte_swp_uffd_wp(*pte))
- new_pte = pte_mkuffd_wp(new_pte);
- set_pte_at(vma->vm_mm, addr, pte, new_pte);
- swap_free(entry);
- out:
- pte_unmap_unlock(pte, ptl);
- if (page != swapcache) {
- unlock_page(page);
- put_page(page);
- }
- return ret;
- }
- static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
- unsigned long addr, unsigned long end,
- unsigned int type)
- {
- swp_entry_t entry;
- pte_t *pte;
- struct swap_info_struct *si;
- int ret = 0;
- volatile unsigned char *swap_map;
- si = swap_info[type];
- pte = pte_offset_map(pmd, addr);
- do {
- struct folio *folio;
- unsigned long offset;
- if (!is_swap_pte(*pte))
- continue;
- entry = pte_to_swp_entry(*pte);
- if (swp_type(entry) != type)
- continue;
- offset = swp_offset(entry);
- pte_unmap(pte);
- swap_map = &si->swap_map[offset];
- folio = swap_cache_get_folio(entry, vma, addr);
- if (!folio) {
- struct page *page;
- struct vm_fault vmf = {
- .vma = vma,
- .address = addr,
- .real_address = addr,
- .pmd = pmd,
- };
- page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE,
- &vmf);
- if (page)
- folio = page_folio(page);
- }
- if (!folio) {
- if (*swap_map == 0 || *swap_map == SWAP_MAP_BAD)
- goto try_next;
- 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);
- goto out;
- }
- folio_free_swap(folio);
- folio_unlock(folio);
- folio_put(folio);
- try_next:
- pte = pte_offset_map(pmd, addr);
- } while (pte++, addr += PAGE_SIZE, addr != end);
- pte_unmap(pte - 1);
- ret = 0;
- out:
- return ret;
- }
- 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);
- if (pmd_none_or_trans_huge_or_clear_bad(pmd))
- continue;
- 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) {
- 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))
- return 0;
- 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), i);
- if (!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;
- }
- 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_readpage
- * 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 *p)
- {
- struct block_device *bdev;
- if (p->bdev)
- bdev = p->bdev;
- else
- bdev = p->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 *p, int prio,
- unsigned char *swap_map,
- struct swap_cluster_info *cluster_info)
- {
- int i;
- if (prio >= 0)
- p->prio = prio;
- else
- p->prio = --least_priority;
- /*
- * the plist prio is negated because plist ordering is
- * low-to-high, while swap ordering is high-to-low
- */
- p->list.prio = -p->prio;
- for_each_node(i) {
- if (p->prio >= 0)
- p->avail_lists[i].prio = -p->prio;
- else {
- if (swap_node(p) == i)
- p->avail_lists[i].prio = 1;
- else
- p->avail_lists[i].prio = -p->prio;
- }
- }
- p->swap_map = swap_map;
- p->cluster_info = cluster_info;
- }
- static void _enable_swap_info(struct swap_info_struct *p)
- {
- p->flags |= SWP_WRITEOK;
- atomic_long_add(p->pages, &nr_swap_pages);
- total_swap_pages += p->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(&p->list, &swap_active_head);
- add_to_avail_list(p);
- }
- static void enable_swap_info(struct swap_info_struct *p, int prio,
- unsigned char *swap_map,
- struct swap_cluster_info *cluster_info,
- unsigned long *frontswap_map)
- {
- if (IS_ENABLED(CONFIG_FRONTSWAP))
- frontswap_init(p->type, frontswap_map);
- spin_lock(&swap_lock);
- spin_lock(&p->lock);
- setup_swap_info(p, prio, swap_map, cluster_info);
- spin_unlock(&p->lock);
- spin_unlock(&swap_lock);
- /*
- * Finished initializing swap device, now it's safe to reference it.
- */
- percpu_ref_resurrect(&p->users);
- spin_lock(&swap_lock);
- spin_lock(&p->lock);
- _enable_swap_info(p);
- spin_unlock(&p->lock);
- spin_unlock(&swap_lock);
- }
- static void reinsert_swap_info(struct swap_info_struct *p)
- {
- spin_lock(&swap_lock);
- spin_lock(&p->lock);
- setup_swap_info(p, p->prio, p->swap_map, p->cluster_info);
- _enable_swap_info(p);
- spin_unlock(&p->lock);
- spin_unlock(&swap_lock);
- }
- bool has_usable_swap(void)
- {
- bool ret = true;
- spin_lock(&swap_lock);
- if (plist_head_empty(&swap_active_head))
- ret = false;
- spin_unlock(&swap_lock);
- return ret;
- }
- SYSCALL_DEFINE1(swapoff, const char __user *, specialfile)
- {
- struct swap_info_struct *p = NULL;
- unsigned char *swap_map;
- struct swap_cluster_info *cluster_info;
- unsigned long *frontswap_map;
- struct file *swap_file, *victim;
- struct address_space *mapping;
- struct inode *inode;
- struct filename *pathname;
- int err, found = 0;
- unsigned int old_block_size;
- bool hibernation_swap = false;
- 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.
- *
- * We need synchronize_rcu() here to protect the accessing to
- * the swap cache data structure.
- */
- percpu_ref_kill(&p->users);
- synchronize_rcu();
- wait_for_completion(&p->comp);
- flush_work(&p->discard_work);
- destroy_swap_extents(p);
- trace_android_vh_check_hibernation_swap(p->bdev, &hibernation_swap);
- if (p->flags & SWP_CONTINUED)
- free_swap_count_continuations(p);
- if (!p->bdev || hibernation_swap ||
- !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;
- old_block_size = p->old_block_size;
- p->swap_file = NULL;
- p->max = 0;
- swap_map = p->swap_map;
- p->swap_map = NULL;
- cluster_info = p->cluster_info;
- p->cluster_info = NULL;
- frontswap_map = frontswap_map_get(p);
- spin_unlock(&p->lock);
- spin_unlock(&swap_lock);
- arch_swap_invalidate_area(p->type);
- frontswap_invalidate_area(p->type);
- frontswap_map_set(p, NULL);
- 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(cluster_info);
- kvfree(frontswap_map);
- /* Destroy swap account information */
- swap_cgroup_swapoff(p->type);
- exit_swap_address_space(p->type);
- inode = mapping->host;
- if (S_ISBLK(inode->i_mode)) {
- struct block_device *bdev = I_BDEV(inode);
- set_blocksize(bdev, old_block_size);
- blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
- }
- 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 = si->pages << (PAGE_SHIFT - 10);
- inuse = READ_ONCE(si->inuse_pages) << (PAGE_SHIFT - 10);
- 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 *p, struct inode *inode)
- {
- int error;
- if (S_ISBLK(inode->i_mode)) {
- p->bdev = blkdev_get_by_dev(inode->i_rdev,
- FMODE_READ | FMODE_WRITE | FMODE_EXCL, p);
- if (IS_ERR(p->bdev)) {
- error = PTR_ERR(p->bdev);
- p->bdev = NULL;
- return error;
- }
- p->old_block_size = block_size(p->bdev);
- error = set_blocksize(p->bdev, PAGE_SIZE);
- if (error < 0)
- return error;
- /*
- * 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(p->bdev))
- return -EINVAL;
- p->flags |= SWP_BLKDEV;
- } else if (S_ISREG(inode->i_mode)) {
- p->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.
- */
- unsigned long generic_max_swapfile_size(void)
- {
- return swp_offset(pte_to_swp_entry(
- swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
- }
- /* Can be overridden by an architecture for additional checks. */
- __weak unsigned long arch_max_swapfile_size(void)
- {
- return generic_max_swapfile_size();
- }
- static unsigned long read_swap_header(struct swap_info_struct *p,
- union swap_header *swap_header,
- struct inode *inode)
- {
- int i;
- unsigned long maxpages;
- unsigned long swapfilepages;
- unsigned long last_page;
- if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) {
- pr_err("Unable to find swap-space signature\n");
- return 0;
- }
- /* swap partition endianness hack... */
- if (swab32(swap_header->info.version) == 1) {
- swab32s(&swap_header->info.version);
- swab32s(&swap_header->info.last_page);
- swab32s(&swap_header->info.nr_badpages);
- if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
- return 0;
- for (i = 0; i < swap_header->info.nr_badpages; i++)
- swab32s(&swap_header->info.badpages[i]);
- }
- /* Check the swap header's sub-version */
- if (swap_header->info.version != 1) {
- pr_warn("Unable to handle swap header version %d\n",
- swap_header->info.version);
- return 0;
- }
- p->lowest_bit = 1;
- p->cluster_next = 1;
- p->cluster_nr = 0;
- maxpages = swapfile_maximum_size;
- last_page = swap_header->info.last_page;
- if (!last_page) {
- pr_warn("Empty swap-file\n");
- return 0;
- }
- if (last_page > maxpages) {
- pr_warn("Truncating oversized swap area, only using %luk out of %luk\n",
- maxpages << (PAGE_SHIFT - 10),
- last_page << (PAGE_SHIFT - 10));
- }
- if (maxpages > last_page) {
- maxpages = last_page + 1;
- /* p->max is an unsigned int: don't overflow it */
- if ((unsigned int)maxpages == 0)
- maxpages = UINT_MAX;
- }
- p->highest_bit = maxpages - 1;
- if (!maxpages)
- return 0;
- swapfilepages = i_size_read(inode) >> PAGE_SHIFT;
- if (swapfilepages && maxpages > swapfilepages) {
- pr_warn("Swap area shorter than signature indicates\n");
- return 0;
- }
- if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode))
- return 0;
- if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES)
- return 0;
- return maxpages;
- }
- #define SWAP_CLUSTER_INFO_COLS \
- DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
- #define SWAP_CLUSTER_SPACE_COLS \
- DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
- #define SWAP_CLUSTER_COLS \
- max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
- static int setup_swap_map_and_extents(struct swap_info_struct *p,
- union swap_header *swap_header,
- unsigned char *swap_map,
- struct swap_cluster_info *cluster_info,
- unsigned long maxpages,
- sector_t *span)
- {
- unsigned int j, k;
- unsigned int nr_good_pages;
- int nr_extents;
- unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
- unsigned long col = p->cluster_next / SWAPFILE_CLUSTER % SWAP_CLUSTER_COLS;
- unsigned long i, idx;
- nr_good_pages = maxpages - 1; /* omit header page */
- cluster_list_init(&p->free_clusters);
- cluster_list_init(&p->discard_clusters);
- for (i = 0; i < swap_header->info.nr_badpages; i++) {
- unsigned int page_nr = swap_header->info.badpages[i];
- if (page_nr == 0 || page_nr > swap_header->info.last_page)
- return -EINVAL;
- if (page_nr < maxpages) {
- swap_map[page_nr] = SWAP_MAP_BAD;
- nr_good_pages--;
- /*
- * Haven't marked the cluster free yet, no list
- * operation involved
- */
- inc_cluster_info_page(p, cluster_info, page_nr);
- }
- }
- /* Haven't marked the cluster free yet, no list operation involved */
- for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++)
- inc_cluster_info_page(p, cluster_info, i);
- if (nr_good_pages) {
- swap_map[0] = SWAP_MAP_BAD;
- /*
- * Not mark the cluster free yet, no list
- * operation involved
- */
- inc_cluster_info_page(p, cluster_info, 0);
- p->max = maxpages;
- p->pages = nr_good_pages;
- nr_extents = setup_swap_extents(p, span);
- if (nr_extents < 0)
- return nr_extents;
- nr_good_pages = p->pages;
- }
- if (!nr_good_pages) {
- pr_warn("Empty swap-file\n");
- return -EINVAL;
- }
- if (!cluster_info)
- return nr_extents;
- /*
- * Reduce false cache line sharing between cluster_info and
- * sharing same address space.
- */
- for (k = 0; k < SWAP_CLUSTER_COLS; k++) {
- j = (k + col) % SWAP_CLUSTER_COLS;
- for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) {
- idx = i * SWAP_CLUSTER_COLS + j;
- if (idx >= nr_clusters)
- continue;
- if (cluster_count(&cluster_info[idx]))
- continue;
- cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE);
- cluster_list_add_tail(&p->free_clusters, cluster_info,
- idx);
- }
- }
- return nr_extents;
- }
- SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags)
- {
- struct swap_info_struct *p;
- struct filename *name;
- struct file *swap_file = NULL;
- struct address_space *mapping;
- struct dentry *dentry;
- int prio;
- int error;
- union swap_header *swap_header;
- int nr_extents;
- sector_t span;
- unsigned long maxpages;
- unsigned char *swap_map = NULL;
- struct swap_cluster_info *cluster_info = NULL;
- unsigned long *frontswap_map = NULL;
- struct page *page = NULL;
- struct inode *inode = NULL;
- bool inced_nr_rotate_swap = false;
- bool hibernation_swap = false;
- if (swap_flags & ~SWAP_FLAGS_VALID)
- return -EINVAL;
- if (!capable(CAP_SYS_ADMIN))
- return -EPERM;
- if (!swap_avail_heads)
- return -ENOMEM;
- p = alloc_swap_info();
- if (IS_ERR(p))
- return PTR_ERR(p);
- INIT_WORK(&p->discard_work, swap_discard_work);
- name = getname(specialfile);
- if (IS_ERR(name)) {
- error = PTR_ERR(name);
- name = NULL;
- goto bad_swap;
- }
- swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0);
- if (IS_ERR(swap_file)) {
- error = PTR_ERR(swap_file);
- swap_file = NULL;
- goto bad_swap;
- }
- p->swap_file = swap_file;
- mapping = swap_file->f_mapping;
- dentry = swap_file->f_path.dentry;
- inode = mapping->host;
- error = claim_swapfile(p, inode);
- if (unlikely(error))
- goto bad_swap;
- inode_lock(inode);
- if (d_unlinked(dentry) || cant_mount(dentry)) {
- error = -ENOENT;
- goto bad_swap_unlock_inode;
- }
- if (IS_SWAPFILE(inode)) {
- error = -EBUSY;
- goto bad_swap_unlock_inode;
- }
- /*
- * Read the swap header.
- */
- if (!mapping->a_ops->read_folio) {
- error = -EINVAL;
- goto bad_swap_unlock_inode;
- }
- page = read_mapping_page(mapping, 0, swap_file);
- if (IS_ERR(page)) {
- error = PTR_ERR(page);
- goto bad_swap_unlock_inode;
- }
- swap_header = kmap(page);
- maxpages = read_swap_header(p, swap_header, inode);
- if (unlikely(!maxpages)) {
- error = -EINVAL;
- goto bad_swap_unlock_inode;
- }
- /* OK, set up the swap map and apply the bad block list */
- swap_map = vzalloc(maxpages);
- if (!swap_map) {
- error = -ENOMEM;
- goto bad_swap_unlock_inode;
- }
- trace_android_vh_check_hibernation_swap(p->bdev, &hibernation_swap);
- if (p->bdev && bdev_stable_writes(p->bdev))
- p->flags |= SWP_STABLE_WRITES;
- if (p->bdev && p->bdev->bd_disk->fops->rw_page)
- p->flags |= SWP_SYNCHRONOUS_IO;
- if (p->bdev && !hibernation_swap &&
- bdev_nonrot(p->bdev)) {
- int cpu;
- unsigned long ci, nr_cluster;
- p->flags |= SWP_SOLIDSTATE;
- p->cluster_next_cpu = alloc_percpu(unsigned int);
- if (!p->cluster_next_cpu) {
- error = -ENOMEM;
- goto bad_swap_unlock_inode;
- }
- /*
- * select a random position to start with to help wear leveling
- * SSD
- */
- for_each_possible_cpu(cpu) {
- per_cpu(*p->cluster_next_cpu, cpu) =
- 1 + prandom_u32_max(p->highest_bit);
- }
- nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER);
- cluster_info = kvcalloc(nr_cluster, sizeof(*cluster_info),
- GFP_KERNEL);
- if (!cluster_info) {
- error = -ENOMEM;
- goto bad_swap_unlock_inode;
- }
- for (ci = 0; ci < nr_cluster; ci++)
- spin_lock_init(&((cluster_info + ci)->lock));
- p->percpu_cluster = alloc_percpu(struct percpu_cluster);
- if (!p->percpu_cluster) {
- error = -ENOMEM;
- goto bad_swap_unlock_inode;
- }
- for_each_possible_cpu(cpu) {
- struct percpu_cluster *cluster;
- cluster = per_cpu_ptr(p->percpu_cluster, cpu);
- cluster_set_null(&cluster->index);
- }
- } else {
- atomic_inc(&nr_rotate_swap);
- inced_nr_rotate_swap = true;
- }
- error = swap_cgroup_swapon(p->type, maxpages);
- if (error)
- goto bad_swap_unlock_inode;
- nr_extents = setup_swap_map_and_extents(p, swap_header, swap_map,
- cluster_info, maxpages, &span);
- if (unlikely(nr_extents < 0)) {
- error = nr_extents;
- goto bad_swap_unlock_inode;
- }
- /* frontswap enabled? set up bit-per-page map for frontswap */
- if (IS_ENABLED(CONFIG_FRONTSWAP))
- frontswap_map = kvcalloc(BITS_TO_LONGS(maxpages),
- sizeof(long),
- GFP_KERNEL);
- if ((swap_flags & SWAP_FLAG_DISCARD) &&
- p->bdev && bdev_max_discard_sectors(p->bdev)) {
- /*
- * When discard is enabled for swap with no particular
- * policy flagged, we set all swap discard flags here in
- * order to sustain backward compatibility with older
- * swapon(8) releases.
- */
- p->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD |
- SWP_PAGE_DISCARD);
- /*
- * By flagging sys_swapon, a sysadmin can tell us to
- * either do single-time area discards only, or to just
- * perform discards for released swap page-clusters.
- * Now it's time to adjust the p->flags accordingly.
- */
- if (swap_flags & SWAP_FLAG_DISCARD_ONCE)
- p->flags &= ~SWP_PAGE_DISCARD;
- else if (swap_flags & SWAP_FLAG_DISCARD_PAGES)
- p->flags &= ~SWP_AREA_DISCARD;
- /* issue a swapon-time discard if it's still required */
- if (p->flags & SWP_AREA_DISCARD) {
- int err = discard_swap(p);
- if (unlikely(err))
- pr_err("swapon: discard_swap(%p): %d\n",
- p, err);
- }
- }
- error = init_swap_address_space(p->type, maxpages);
- if (error)
- goto bad_swap_unlock_inode;
- /*
- * Flush any pending IO and dirty mappings before we start using this
- * swap device.
- */
- inode->i_flags |= S_SWAPFILE;
- error = inode_drain_writes(inode);
- if (error) {
- inode->i_flags &= ~S_SWAPFILE;
- goto free_swap_address_space;
- }
- mutex_lock(&swapon_mutex);
- prio = -1;
- if (swap_flags & SWAP_FLAG_PREFER)
- prio =
- (swap_flags & SWAP_FLAG_PRIO_MASK) >> SWAP_FLAG_PRIO_SHIFT;
- enable_swap_info(p, prio, swap_map, cluster_info, frontswap_map);
- pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
- p->pages<<(PAGE_SHIFT-10), name->name, p->prio,
- nr_extents, (unsigned long long)span<<(PAGE_SHIFT-10),
- (p->flags & SWP_SOLIDSTATE) ? "SS" : "",
- (p->flags & SWP_DISCARDABLE) ? "D" : "",
- (p->flags & SWP_AREA_DISCARD) ? "s" : "",
- (p->flags & SWP_PAGE_DISCARD) ? "c" : "",
- (frontswap_map) ? "FS" : "");
- mutex_unlock(&swapon_mutex);
- atomic_inc(&proc_poll_event);
- wake_up_interruptible(&proc_poll_wait);
- error = 0;
- goto out;
- free_swap_address_space:
- exit_swap_address_space(p->type);
- bad_swap_unlock_inode:
- inode_unlock(inode);
- bad_swap:
- free_percpu(p->percpu_cluster);
- p->percpu_cluster = NULL;
- free_percpu(p->cluster_next_cpu);
- p->cluster_next_cpu = NULL;
- if (inode && S_ISBLK(inode->i_mode) && p->bdev) {
- set_blocksize(p->bdev, p->old_block_size);
- blkdev_put(p->bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL);
- }
- inode = NULL;
- destroy_swap_extents(p);
- swap_cgroup_swapoff(p->type);
- spin_lock(&swap_lock);
- p->swap_file = NULL;
- p->flags = 0;
- spin_unlock(&swap_lock);
- vfree(swap_map);
- kvfree(cluster_info);
- kvfree(frontswap_map);
- if (inced_nr_rotate_swap)
- atomic_dec(&nr_rotate_swap);
- if (swap_file)
- filp_close(swap_file, NULL);
- out:
- if (page && !IS_ERR(page)) {
- kunmap(page);
- put_page(page);
- }
- if (name)
- putname(name);
- if (inode)
- inode_unlock(inode);
- if (!error)
- enable_swap_slots_cache();
- return error;
- }
- void si_swapinfo(struct sysinfo *val)
- {
- unsigned int type;
- unsigned long nr_to_be_unused = 0;
- spin_lock(&swap_lock);
- for (type = 0; type < nr_swapfiles; type++) {
- struct swap_info_struct *si = swap_info[type];
- if ((si->flags & SWP_USED) && !(si->flags & SWP_WRITEOK))
- nr_to_be_unused += READ_ONCE(si->inuse_pages);
- }
- val->freeswap = atomic_long_read(&nr_swap_pages) + nr_to_be_unused;
- val->totalswap = total_swap_pages + nr_to_be_unused;
- spin_unlock(&swap_lock);
- }
- EXPORT_SYMBOL_NS_GPL(si_swapinfo, MINIDUMP);
- /*
- * Verify that a swap entry is valid and increment its swap map count.
- *
- * Returns error code in following case.
- * - success -> 0
- * - swp_entry is invalid -> EINVAL
- * - swp_entry is migration entry -> EINVAL
- * - swap-cache reference is requested but there is already one. -> EEXIST
- * - swap-cache reference is requested but the entry is not used. -> ENOENT
- * - swap-mapped reference requested but needs continued swap count. -> ENOMEM
- */
- static int __swap_duplicate(swp_entry_t entry, unsigned char usage)
- {
- struct swap_info_struct *p;
- struct swap_cluster_info *ci;
- unsigned long offset;
- unsigned char count;
- unsigned char has_cache;
- int err;
- p = get_swap_device(entry);
- if (!p)
- return -EINVAL;
- offset = swp_offset(entry);
- ci = lock_cluster_or_swap_info(p, offset);
- count = p->swap_map[offset];
- /*
- * swapin_readahead() doesn't check if a swap entry is valid, so the
- * swap entry could be SWAP_MAP_BAD. Check here with lock held.
- */
- if (unlikely(swap_count(count) == SWAP_MAP_BAD)) {
- err = -ENOENT;
- goto unlock_out;
- }
- has_cache = count & SWAP_HAS_CACHE;
- count &= ~SWAP_HAS_CACHE;
- err = 0;
- if (usage == SWAP_HAS_CACHE) {
- /* set SWAP_HAS_CACHE if there is no cache and entry is used */
- if (!has_cache && count)
- has_cache = SWAP_HAS_CACHE;
- else if (has_cache) /* someone else added cache */
- err = -EEXIST;
- else /* no users remaining */
- err = -ENOENT;
- } else if (count || has_cache) {
- if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX)
- count += usage;
- else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX)
- err = -EINVAL;
- else if (swap_count_continued(p, offset, count))
- count = COUNT_CONTINUED;
- else
- err = -ENOMEM;
- } else
- err = -ENOENT; /* unused swap entry */
- WRITE_ONCE(p->swap_map[offset], count | has_cache);
- unlock_out:
- unlock_cluster_or_swap_info(p, ci);
- put_swap_device(p);
- return err;
- }
- /*
- * Help swapoff by noting that swap entry belongs to shmem/tmpfs
- * (in which case its reference count is never incremented).
- */
- void swap_shmem_alloc(swp_entry_t entry)
- {
- __swap_duplicate(entry, SWAP_MAP_SHMEM);
- }
- /*
- * Increase reference count of swap entry by 1.
- * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
- * but could not be atomically allocated. Returns 0, just as if it succeeded,
- * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
- * might occur if a page table entry has got corrupted.
- */
- int swap_duplicate(swp_entry_t entry)
- {
- int err = 0;
- while (!err && __swap_duplicate(entry, 1) == -ENOMEM)
- err = add_swap_count_continuation(entry, GFP_ATOMIC);
- return err;
- }
- /*
- * @entry: swap entry for which we allocate swap cache.
- *
- * Called when allocating swap cache for existing swap entry,
- * This can return error codes. Returns 0 at success.
- * -EEXIST means there is a swap cache.
- * Note: return code is different from swap_duplicate().
- */
- int swapcache_prepare(swp_entry_t entry)
- {
- return __swap_duplicate(entry, SWAP_HAS_CACHE);
- }
- struct swap_info_struct *swp_swap_info(swp_entry_t entry)
- {
- return swap_type_to_swap_info(swp_type(entry));
- }
- struct swap_info_struct *page_swap_info(struct page *page)
- {
- swp_entry_t entry = { .val = page_private(page) };
- return swp_swap_info(entry);
- }
- /*
- * out-of-line methods to avoid include hell.
- */
- struct address_space *swapcache_mapping(struct folio *folio)
- {
- return page_swap_info(&folio->page)->swap_file->f_mapping;
- }
- EXPORT_SYMBOL_GPL(swapcache_mapping);
- pgoff_t __page_file_index(struct page *page)
- {
- swp_entry_t swap = { .val = page_private(page) };
- return swp_offset(swap);
- }
- EXPORT_SYMBOL_GPL(__page_file_index);
- /*
- * add_swap_count_continuation - called when a swap count is duplicated
- * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
- * page of the original vmalloc'ed swap_map, to hold the continuation count
- * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called
- * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
- *
- * These continuation pages are seldom referenced: the common paths all work
- * on the original swap_map, only referring to a continuation page when the
- * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
- *
- * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
- * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
- * can be called after dropping locks.
- */
- int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask)
- {
- struct swap_info_struct *si;
- struct swap_cluster_info *ci;
- struct page *head;
- struct page *page;
- struct page *list_page;
- pgoff_t offset;
- unsigned char count;
- int ret = 0;
- /*
- * When debugging, it's easier to use __GFP_ZERO here; but it's better
- * for latency not to zero a page while GFP_ATOMIC and holding locks.
- */
- page = alloc_page(gfp_mask | __GFP_HIGHMEM);
- si = get_swap_device(entry);
- if (!si) {
- /*
- * An acceptable race has occurred since the failing
- * __swap_duplicate(): the swap device may be swapoff
- */
- goto outer;
- }
- spin_lock(&si->lock);
- offset = swp_offset(entry);
- ci = lock_cluster(si, offset);
- count = swap_count(si->swap_map[offset]);
- if ((count & ~COUNT_CONTINUED) != SWAP_MAP_MAX) {
- /*
- * The higher the swap count, the more likely it is that tasks
- * will race to add swap count continuation: we need to avoid
- * over-provisioning.
- */
- goto out;
- }
- if (!page) {
- ret = -ENOMEM;
- goto out;
- }
- /*
- * We are fortunate that although vmalloc_to_page uses pte_offset_map,
- * no architecture is using highmem pages for kernel page tables: so it
- * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps.
- */
- head = vmalloc_to_page(si->swap_map + offset);
- offset &= ~PAGE_MASK;
- spin_lock(&si->cont_lock);
- /*
- * Page allocation does not initialize the page's lru field,
- * but it does always reset its private field.
- */
- if (!page_private(head)) {
- BUG_ON(count & COUNT_CONTINUED);
- INIT_LIST_HEAD(&head->lru);
- set_page_private(head, SWP_CONTINUED);
- si->flags |= SWP_CONTINUED;
- }
- list_for_each_entry(list_page, &head->lru, lru) {
- unsigned char *map;
- /*
- * If the previous map said no continuation, but we've found
- * a continuation page, free our allocation and use this one.
- */
- if (!(count & COUNT_CONTINUED))
- goto out_unlock_cont;
- map = kmap_atomic(list_page) + offset;
- count = *map;
- kunmap_atomic(map);
- /*
- * If this continuation count now has some space in it,
- * free our allocation and use this one.
- */
- if ((count & ~COUNT_CONTINUED) != SWAP_CONT_MAX)
- goto out_unlock_cont;
- }
- list_add_tail(&page->lru, &head->lru);
- page = NULL; /* now it's attached, don't free it */
- out_unlock_cont:
- spin_unlock(&si->cont_lock);
- out:
- unlock_cluster(ci);
- spin_unlock(&si->lock);
- put_swap_device(si);
- outer:
- if (page)
- __free_page(page);
- return ret;
- }
- /*
- * swap_count_continued - when the original swap_map count is incremented
- * from SWAP_MAP_MAX, check if there is already a continuation page to carry
- * into, carry if so, or else fail until a new continuation page is allocated;
- * when the original swap_map count is decremented from 0 with continuation,
- * borrow from the continuation and report whether it still holds more.
- * Called while __swap_duplicate() or swap_entry_free() holds swap or cluster
- * lock.
- */
- static bool swap_count_continued(struct swap_info_struct *si,
- pgoff_t offset, unsigned char count)
- {
- struct page *head;
- struct page *page;
- unsigned char *map;
- bool ret;
- head = vmalloc_to_page(si->swap_map + offset);
- if (page_private(head) != SWP_CONTINUED) {
- BUG_ON(count & COUNT_CONTINUED);
- return false; /* need to add count continuation */
- }
- spin_lock(&si->cont_lock);
- offset &= ~PAGE_MASK;
- page = list_next_entry(head, lru);
- map = kmap_atomic(page) + offset;
- if (count == SWAP_MAP_MAX) /* initial increment from swap_map */
- goto init_map; /* jump over SWAP_CONT_MAX checks */
- if (count == (SWAP_MAP_MAX | COUNT_CONTINUED)) { /* incrementing */
- /*
- * Think of how you add 1 to 999
- */
- while (*map == (SWAP_CONT_MAX | COUNT_CONTINUED)) {
- kunmap_atomic(map);
- page = list_next_entry(page, lru);
- BUG_ON(page == head);
- map = kmap_atomic(page) + offset;
- }
- if (*map == SWAP_CONT_MAX) {
- kunmap_atomic(map);
- page = list_next_entry(page, lru);
- if (page == head) {
- ret = false; /* add count continuation */
- goto out;
- }
- map = kmap_atomic(page) + offset;
- init_map: *map = 0; /* we didn't zero the page */
- }
- *map += 1;
- kunmap_atomic(map);
- while ((page = list_prev_entry(page, lru)) != head) {
- map = kmap_atomic(page) + offset;
- *map = COUNT_CONTINUED;
- kunmap_atomic(map);
- }
- ret = true; /* incremented */
- } else { /* decrementing */
- /*
- * Think of how you subtract 1 from 1000
- */
- BUG_ON(count != COUNT_CONTINUED);
- while (*map == COUNT_CONTINUED) {
- kunmap_atomic(map);
- page = list_next_entry(page, lru);
- BUG_ON(page == head);
- map = kmap_atomic(page) + offset;
- }
- BUG_ON(*map == 0);
- *map -= 1;
- if (*map == 0)
- count = 0;
- kunmap_atomic(map);
- while ((page = list_prev_entry(page, lru)) != head) {
- map = kmap_atomic(page) + offset;
- *map = SWAP_CONT_MAX | count;
- count = COUNT_CONTINUED;
- kunmap_atomic(map);
- }
- ret = count == COUNT_CONTINUED;
- }
- out:
- spin_unlock(&si->cont_lock);
- return ret;
- }
- /*
- * free_swap_count_continuations - swapoff free all the continuation pages
- * appended to the swap_map, after swap_map is quiesced, before vfree'ing it.
- */
- static void free_swap_count_continuations(struct swap_info_struct *si)
- {
- pgoff_t offset;
- for (offset = 0; offset < si->max; offset += PAGE_SIZE) {
- struct page *head;
- head = vmalloc_to_page(si->swap_map + offset);
- if (page_private(head)) {
- struct page *page, *next;
- list_for_each_entry_safe(page, next, &head->lru, lru) {
- list_del(&page->lru);
- __free_page(page);
- }
- }
- }
- }
- #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
- void __cgroup_throttle_swaprate(struct page *page, gfp_t gfp_mask)
- {
- struct swap_info_struct *si, *next;
- int nid = page_to_nid(page);
- if (!(gfp_mask & __GFP_IO))
- return;
- if (!blk_cgroup_congested())
- return;
- /*
- * We've already scheduled a throttle, avoid taking the global swap
- * lock.
- */
- if (current->throttle_queue)
- return;
- spin_lock(&swap_avail_lock);
- plist_for_each_entry_safe(si, next, &swap_avail_heads[nid],
- avail_lists[nid]) {
- if (si->bdev) {
- blkcg_schedule_throttle(si->bdev->bd_disk, true);
- break;
- }
- }
- spin_unlock(&swap_avail_lock);
- }
- #endif
- static int __init swapfile_init(void)
- {
- int nid;
- swap_avail_heads = kmalloc_array(nr_node_ids, sizeof(struct plist_head),
- GFP_KERNEL);
- if (!swap_avail_heads) {
- pr_emerg("Not enough memory for swap heads, swap is disabled\n");
- return -ENOMEM;
- }
- for_each_node(nid)
- plist_head_init(&swap_avail_heads[nid]);
- swapfile_maximum_size = arch_max_swapfile_size();
- #ifdef CONFIG_MIGRATION
- if (swapfile_maximum_size >= (1UL << SWP_MIG_TOTAL_BITS))
- swap_migration_ad_supported = true;
- #endif /* CONFIG_MIGRATION */
- return 0;
- }
- subsys_initcall(swapfile_init);
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