diff options
Diffstat (limited to 'mm/swapfile.c')
| -rw-r--r-- | mm/swapfile.c | 2603 |
1 files changed, 1427 insertions, 1176 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index 4919423cce76..68ce283e84be 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -37,7 +37,6 @@ #include <linux/oom.h> #include <linux/swapfile.h> #include <linux/export.h> -#include <linux/swap_slots.h> #include <linux/sort.h> #include <linux/completion.h> #include <linux/suspend.h> @@ -53,6 +52,15 @@ static bool swap_count_continued(struct swap_info_struct *, pgoff_t, unsigned char); static void free_swap_count_continuations(struct swap_info_struct *); +static void swap_entries_free(struct swap_info_struct *si, + struct swap_cluster_info *ci, + swp_entry_t entry, unsigned int nr_pages); +static void swap_range_alloc(struct swap_info_struct *si, + unsigned int nr_entries); +static bool folio_swapcache_freeable(struct folio *folio); +static struct swap_cluster_info *lock_cluster(struct swap_info_struct *si, + unsigned long offset); +static inline void unlock_cluster(struct swap_cluster_info *ci); static DEFINE_SPINLOCK(swap_lock); static unsigned int nr_swapfiles; @@ -107,6 +115,18 @@ static atomic_t proc_poll_event = ATOMIC_INIT(0); atomic_t nr_rotate_swap = ATOMIC_INIT(0); +struct percpu_swap_cluster { + struct swap_info_struct *si[SWAP_NR_ORDERS]; + unsigned long offset[SWAP_NR_ORDERS]; + local_lock_t lock; +}; + +static DEFINE_PER_CPU(struct percpu_swap_cluster, percpu_swap_cluster) = { + .si = { NULL }, + .offset = { SWAP_ENTRY_INVALID }, + .lock = INIT_LOCAL_LOCK(), +}; + static struct swap_info_struct *swap_type_to_swap_info(int type) { if (type >= MAX_SWAPFILES) @@ -120,6 +140,26 @@ static inline unsigned char swap_count(unsigned char ent) return ent & ~SWAP_HAS_CACHE; /* may include COUNT_CONTINUED flag */ } +/* + * Use the second highest bit of inuse_pages counter as the indicator + * if one swap device is on the available plist, so the atomic can + * still be updated arithmetically while having special data embedded. + * + * inuse_pages counter is the only thing indicating if a device should + * be on avail_lists or not (except swapon / swapoff). By embedding the + * off-list bit in the atomic counter, updates no longer need any lock + * to check the list status. + * + * This bit will be set if the device is not on the plist and not + * usable, will be cleared if the device is on the plist. + */ +#define SWAP_USAGE_OFFLIST_BIT (1UL << (BITS_PER_TYPE(atomic_t) - 2)) +#define SWAP_USAGE_COUNTER_MASK (~SWAP_USAGE_OFFLIST_BIT) +static long swap_usage_in_pages(struct swap_info_struct *si) +{ + return atomic_long_read(&si->inuse_pages) & SWAP_USAGE_COUNTER_MASK; +} + /* Reclaim the swap entry anyway if possible */ #define TTRS_ANYWAY 0x1 /* @@ -127,20 +167,66 @@ static inline unsigned char swap_count(unsigned char ent) * corresponding page */ #define TTRS_UNMAPPED 0x2 -/* Reclaim the swap entry if swap is getting full*/ +/* Reclaim the swap entry if swap is getting full */ #define TTRS_FULL 0x4 -/* returns 1 if swap entry is freed */ +static bool swap_only_has_cache(struct swap_info_struct *si, + unsigned long offset, int nr_pages) +{ + unsigned char *map = si->swap_map + offset; + unsigned char *map_end = map + nr_pages; + + do { + VM_BUG_ON(!(*map & SWAP_HAS_CACHE)); + if (*map != SWAP_HAS_CACHE) + return false; + } while (++map < map_end); + + return true; +} + +static bool swap_is_last_map(struct swap_info_struct *si, + unsigned long offset, int nr_pages, bool *has_cache) +{ + unsigned char *map = si->swap_map + offset; + unsigned char *map_end = map + nr_pages; + unsigned char count = *map; + + if (swap_count(count) != 1 && swap_count(count) != SWAP_MAP_SHMEM) + return false; + + while (++map < map_end) { + if (*map != count) + return false; + } + + *has_cache = !!(count & SWAP_HAS_CACHE); + return true; +} + +/* + * returns number of pages in the folio that backs the swap entry. If positive, + * the folio was reclaimed. If negative, the folio was not reclaimed. If 0, no + * folio was associated with the swap entry. + */ static int __try_to_reclaim_swap(struct swap_info_struct *si, unsigned long offset, unsigned long flags) { swp_entry_t entry = swp_entry(si->type, offset); + struct address_space *address_space = swap_address_space(entry); + struct swap_cluster_info *ci; struct folio *folio; - int ret = 0; + int ret, nr_pages; + bool need_reclaim; - folio = filemap_get_folio(swap_address_space(entry), offset); +again: + folio = filemap_get_folio(address_space, swap_cache_index(entry)); if (IS_ERR(folio)) return 0; + + nr_pages = folio_nr_pages(folio); + ret = -nr_pages; + /* * When this function is called from scan_swap_map_slots() and it's * called by vmscan.c at reclaiming folios. So we hold a folio lock @@ -148,13 +234,44 @@ static int __try_to_reclaim_swap(struct swap_info_struct *si, * 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); + if (!folio_trylock(folio)) + goto out; + + /* + * Offset could point to the middle of a large folio, or folio + * may no longer point to the expected offset before it's locked. + */ + entry = folio->swap; + if (offset < swp_offset(entry) || offset >= swp_offset(entry) + nr_pages) { folio_unlock(folio); + folio_put(folio); + goto again; } + offset = swp_offset(entry); + + need_reclaim = ((flags & TTRS_ANYWAY) || + ((flags & TTRS_UNMAPPED) && !folio_mapped(folio)) || + ((flags & TTRS_FULL) && mem_cgroup_swap_full(folio))); + if (!need_reclaim || !folio_swapcache_freeable(folio)) + goto out_unlock; + + /* + * It's safe to delete the folio from swap cache only if the folio's + * swap_map is HAS_CACHE only, which means the slots have no page table + * reference or pending writeback, and can't be allocated to others. + */ + ci = lock_cluster(si, offset); + need_reclaim = swap_only_has_cache(si, offset, nr_pages); + unlock_cluster(ci); + if (!need_reclaim) + goto out_unlock; + + delete_from_swap_cache(folio); + folio_set_dirty(folio); + ret = nr_pages; +out_unlock: + folio_unlock(folio); +out: folio_put(folio); return ret; } @@ -273,86 +390,53 @@ static void discard_swap_cluster(struct swap_info_struct *si, #ifdef CONFIG_THP_SWAP #define SWAPFILE_CLUSTER HPAGE_PMD_NR -#define swap_entry_size(size) (size) +#define swap_entry_order(order) (order) #else #define SWAPFILE_CLUSTER 256 /* - * Define swap_entry_size() as constant to let compiler to optimize + * Define swap_entry_order() as constant to let compiler to optimize * out some code if !CONFIG_THP_SWAP */ -#define swap_entry_size(size) 1 +#define swap_entry_order(order) 0 #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) +static inline bool cluster_is_empty(struct swap_cluster_info *info) { - return info->data; + return info->count == 0; } -static inline void cluster_set_count(struct swap_cluster_info *info, - unsigned int c) +static inline bool cluster_is_discard(struct swap_cluster_info *info) { - info->data = c; + return info->flags == CLUSTER_FLAG_DISCARD; } -static inline void cluster_set_count_flag(struct swap_cluster_info *info, - unsigned int c, unsigned int f) +static inline bool cluster_is_usable(struct swap_cluster_info *ci, int order) { - 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; + if (unlikely(ci->flags > CLUSTER_FLAG_USABLE)) + return false; + if (!order) + return true; + return cluster_is_empty(ci) || order == ci->order; } -static inline void cluster_set_null(struct swap_cluster_info *info) +static inline unsigned int cluster_index(struct swap_info_struct *si, + struct swap_cluster_info *ci) { - info->flags = CLUSTER_FLAG_NEXT_NULL; - info->data = 0; + return ci - si->cluster_info; } -static inline bool cluster_is_huge(struct swap_cluster_info *info) +static inline struct swap_cluster_info *offset_to_cluster(struct swap_info_struct *si, + unsigned long offset) { - if (IS_ENABLED(CONFIG_THP_SWAP)) - return info->flags & CLUSTER_FLAG_HUGE; - return false; + return &si->cluster_info[offset / SWAPFILE_CLUSTER]; } -static inline void cluster_clear_huge(struct swap_cluster_info *info) +static inline unsigned int cluster_offset(struct swap_info_struct *si, + struct swap_cluster_info *ci) { - info->flags &= ~CLUSTER_FLAG_HUGE; + return cluster_index(si, ci) * SWAPFILE_CLUSTER; } static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si, @@ -360,153 +444,134 @@ static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si { struct swap_cluster_info *ci; - ci = si->cluster_info; - if (ci) { - ci += offset / SWAPFILE_CLUSTER; - spin_lock(&ci->lock); - } + ci = offset_to_cluster(si, offset); + spin_lock(&ci->lock); + return ci; } static inline void unlock_cluster(struct swap_cluster_info *ci) { - if (ci) - spin_unlock(&ci->lock); + 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) +static void move_cluster(struct swap_info_struct *si, + struct swap_cluster_info *ci, struct list_head *list, + enum swap_cluster_flags new_flags) { - 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); + VM_WARN_ON(ci->flags == new_flags); - return ci; -} + BUILD_BUG_ON(1 << sizeof(ci->flags) * BITS_PER_BYTE < CLUSTER_FLAG_MAX); + lockdep_assert_held(&ci->lock); -static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si, - struct swap_cluster_info *ci) -{ - if (ci) - unlock_cluster(ci); + spin_lock(&si->lock); + if (ci->flags == CLUSTER_FLAG_NONE) + list_add_tail(&ci->list, list); else - spin_unlock(&si->lock); -} - -static inline bool cluster_list_empty(struct swap_cluster_list *list) -{ - return cluster_is_null(&list->head); -} + list_move_tail(&ci->list, list); + spin_unlock(&si->lock); -static inline unsigned int cluster_list_first(struct swap_cluster_list *list) -{ - return cluster_next(&list->head); + if (ci->flags == CLUSTER_FLAG_FRAG) + atomic_long_dec(&si->frag_cluster_nr[ci->order]); + else if (new_flags == CLUSTER_FLAG_FRAG) + atomic_long_inc(&si->frag_cluster_nr[ci->order]); + ci->flags = new_flags; } -static void cluster_list_init(struct swap_cluster_list *list) +/* Add a cluster to discard list and schedule it to do discard */ +static void swap_cluster_schedule_discard(struct swap_info_struct *si, + struct swap_cluster_info *ci) { - cluster_set_null(&list->head); - cluster_set_null(&list->tail); + VM_BUG_ON(ci->flags == CLUSTER_FLAG_FREE); + move_cluster(si, ci, &si->discard_clusters, CLUSTER_FLAG_DISCARD); + schedule_work(&si->discard_work); } -static void cluster_list_add_tail(struct swap_cluster_list *list, - struct swap_cluster_info *ci, - unsigned int idx) +static void __free_cluster(struct swap_info_struct *si, struct swap_cluster_info *ci) { - 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); - } + lockdep_assert_held(&ci->lock); + move_cluster(si, ci, &si->free_clusters, CLUSTER_FLAG_FREE); + ci->order = 0; } -static unsigned int cluster_list_del_first(struct swap_cluster_list *list, - struct swap_cluster_info *ci) +/* + * Isolate and lock the first cluster that is not contented on a list, + * clean its flag before taken off-list. Cluster flag must be in sync + * with list status, so cluster updaters can always know the cluster + * list status without touching si lock. + * + * Note it's possible that all clusters on a list are contented so + * this returns NULL for an non-empty list. + */ +static struct swap_cluster_info *isolate_lock_cluster( + struct swap_info_struct *si, struct list_head *list) { - unsigned int idx; + struct swap_cluster_info *ci, *ret = NULL; - 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; -} + spin_lock(&si->lock); -/* Add a cluster to discard list and schedule it to do discard */ -static void swap_cluster_schedule_discard(struct swap_info_struct *si, - 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); + if (unlikely(!(si->flags & SWP_WRITEOK))) + goto out; - cluster_list_add_tail(&si->discard_clusters, si->cluster_info, idx); + list_for_each_entry(ci, list, list) { + if (!spin_trylock(&ci->lock)) + continue; - schedule_work(&si->discard_work); -} + /* We may only isolate and clear flags of following lists */ + VM_BUG_ON(!ci->flags); + VM_BUG_ON(ci->flags > CLUSTER_FLAG_USABLE && + ci->flags != CLUSTER_FLAG_FULL); -static void __free_cluster(struct swap_info_struct *si, unsigned long idx) -{ - struct swap_cluster_info *ci = si->cluster_info; + list_del(&ci->list); + ci->flags = CLUSTER_FLAG_NONE; + ret = ci; + break; + } +out: + spin_unlock(&si->lock); - cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE); - cluster_list_add_tail(&si->free_clusters, ci, idx); + return ret; } /* * 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) + * will be added to free cluster list. Discard cluster is a bit special as + * they don't participate in allocation or reclaim, so clusters marked as + * CLUSTER_FLAG_DISCARD must remain off-list or on discard list. + */ +static bool swap_do_scheduled_discard(struct swap_info_struct *si) { - struct swap_cluster_info *info, *ci; + struct swap_cluster_info *ci; + bool ret = false; unsigned int idx; - info = si->cluster_info; - - while (!cluster_list_empty(&si->discard_clusters)) { - idx = cluster_list_del_first(&si->discard_clusters, info); + spin_lock(&si->lock); + while (!list_empty(&si->discard_clusters)) { + ci = list_first_entry(&si->discard_clusters, struct swap_cluster_info, list); + /* + * Delete the cluster from list to prepare for discard, but keep + * the CLUSTER_FLAG_DISCARD flag, percpu_swap_cluster could be + * pointing to it, or ran into by relocate_cluster. + */ + list_del(&ci->list); + idx = cluster_index(si, ci); spin_unlock(&si->lock); - discard_swap_cluster(si, idx * SWAPFILE_CLUSTER, SWAPFILE_CLUSTER); + spin_lock(&ci->lock); + /* + * Discard is done, clear its flags as it's off-list, then + * return the cluster to allocation list. + */ + ci->flags = CLUSTER_FLAG_NONE; + __free_cluster(si, ci); + spin_unlock(&ci->lock); + ret = true; 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); } + spin_unlock(&si->lock); + return ret; } static void swap_discard_work(struct work_struct *work) @@ -515,9 +580,7 @@ static void swap_discard_work(struct work_struct *work) 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) @@ -528,20 +591,16 @@ static void swap_users_ref_free(struct percpu_ref *ref) 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) +/* + * Must be called after freeing if ci->count == 0, moves the cluster to free + * or discard list. + */ +static void free_cluster(struct swap_info_struct *si, struct swap_cluster_info *ci) { - struct swap_cluster_info *ci = si->cluster_info + idx; + VM_BUG_ON(ci->count != 0); + VM_BUG_ON(ci->flags == CLUSTER_FLAG_FREE); + lockdep_assert_held(&ci->lock); - 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 @@ -549,566 +608,632 @@ static void free_cluster(struct swap_info_struct *si, unsigned long idx) */ if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == (SWP_WRITEOK | SWP_PAGE_DISCARD)) { - swap_cluster_schedule_discard(si, idx); + swap_cluster_schedule_discard(si, ci); return; } - __free_cluster(si, idx); + __free_cluster(si, ci); } /* - * 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. + * Must be called after freeing if ci->count != 0, moves the cluster to + * nonfull list. */ -static void inc_cluster_info_page(struct swap_info_struct *p, - struct swap_cluster_info *cluster_info, unsigned long page_nr) +static void partial_free_cluster(struct swap_info_struct *si, + struct swap_cluster_info *ci) { - 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(!ci->count || ci->count == SWAPFILE_CLUSTER); + lockdep_assert_held(&ci->lock); - VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); - cluster_set_count(&cluster_info[idx], - cluster_count(&cluster_info[idx]) + 1); + if (ci->flags != CLUSTER_FLAG_NONFULL) + move_cluster(si, ci, &si->nonfull_clusters[ci->order], + CLUSTER_FLAG_NONFULL); } /* - * 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. + * Must be called after allocation, moves the cluster to full or frag list. + * Note: allocation doesn't acquire si lock, and may drop the ci lock for + * reclaim, so the cluster could be any where when called. */ -static void dec_cluster_info_page(struct swap_info_struct *p, - struct swap_cluster_info *cluster_info, unsigned long page_nr) +static void relocate_cluster(struct swap_info_struct *si, + struct swap_cluster_info *ci) { - unsigned long idx = page_nr / SWAPFILE_CLUSTER; + lockdep_assert_held(&ci->lock); - if (!cluster_info) + /* Discard cluster must remain off-list or on discard list */ + if (cluster_is_discard(ci)) 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); + if (!ci->count) { + if (ci->flags != CLUSTER_FLAG_FREE) + free_cluster(si, ci); + } else if (ci->count != SWAPFILE_CLUSTER) { + if (ci->flags != CLUSTER_FLAG_FRAG) + move_cluster(si, ci, &si->frag_clusters[ci->order], + CLUSTER_FLAG_FRAG); + } else { + if (ci->flags != CLUSTER_FLAG_FULL) + move_cluster(si, ci, &si->full_clusters, + CLUSTER_FLAG_FULL); + } } /* - * 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. + * The cluster corresponding to page_nr will be used. The cluster will not be + * added to free cluster list and its usage counter will be increased by 1. + * Only used for initialization. */ -static bool -scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, - unsigned long offset) +static void inc_cluster_info_page(struct swap_info_struct *si, + struct swap_cluster_info *cluster_info, unsigned long page_nr) { - 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]); + unsigned long idx = page_nr / SWAPFILE_CLUSTER; + struct swap_cluster_info *ci; - if (!conflict) - return false; + ci = cluster_info + idx; + ci->count++; - percpu_cluster = this_cpu_ptr(si->percpu_cluster); - cluster_set_null(&percpu_cluster->index); - return true; + VM_BUG_ON(ci->count > SWAPFILE_CLUSTER); + VM_BUG_ON(ci->flags); } -/* - * 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) +static bool cluster_reclaim_range(struct swap_info_struct *si, + struct swap_cluster_info *ci, + unsigned long start, unsigned long end) { - 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; - } + unsigned char *map = si->swap_map; + unsigned long offset = start; + int nr_reclaim; + spin_unlock(&ci->lock); + do { + switch (READ_ONCE(map[offset])) { + case 0: + offset++; + break; + case SWAP_HAS_CACHE: + nr_reclaim = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY); + if (nr_reclaim > 0) + offset += nr_reclaim; + else + goto out; + break; + default: + goto out; + } + } while (offset < end); +out: + spin_lock(&ci->lock); /* - * Other CPUs can use our cluster if they can't find a free cluster, - * check if there is still free entry in the cluster + * Recheck the range no matter reclaim succeeded or not, the slot + * could have been be freed while we are not holding the lock. */ - 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; + for (offset = start; offset < end; offset++) + if (READ_ONCE(map[offset])) + return false; + return true; } -static void __del_from_avail_list(struct swap_info_struct *p) +static bool cluster_scan_range(struct swap_info_struct *si, + struct swap_cluster_info *ci, + unsigned long start, unsigned int nr_pages, + bool *need_reclaim) { - int nid; + unsigned long offset, end = start + nr_pages; + unsigned char *map = si->swap_map; - assert_spin_locked(&p->lock); - for_each_node(nid) - plist_del(&p->avail_lists[nid], &swap_avail_heads[nid]); -} + if (cluster_is_empty(ci)) + return true; -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); + for (offset = start; offset < end; offset++) { + switch (READ_ONCE(map[offset])) { + case 0: + continue; + case SWAP_HAS_CACHE: + if (!vm_swap_full()) + return false; + *need_reclaim = true; + continue; + default: + return false; + } + } + + return true; } -static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, - unsigned int nr_entries) +static bool cluster_alloc_range(struct swap_info_struct *si, struct swap_cluster_info *ci, + unsigned int start, unsigned char usage, + unsigned int order) { - unsigned int end = offset + nr_entries - 1; + unsigned int nr_pages = 1 << order; - 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); - } -} + lockdep_assert_held(&ci->lock); -static void add_to_avail_list(struct swap_info_struct *p) -{ - int nid; + if (!(si->flags & SWP_WRITEOK)) + return false; - spin_lock(&swap_avail_lock); - for_each_node(nid) - plist_add(&p->avail_lists[nid], &swap_avail_heads[nid]); - spin_unlock(&swap_avail_lock); + /* + * The first allocation in a cluster makes the + * cluster exclusive to this order + */ + if (cluster_is_empty(ci)) + ci->order = order; + + memset(si->swap_map + start, usage, nr_pages); + swap_range_alloc(si, nr_pages); + ci->count += nr_pages; + + return true; } -static void swap_range_free(struct swap_info_struct *si, unsigned long offset, - unsigned int nr_entries) +/* Try use a new cluster for current CPU and allocate from it. */ +static unsigned int alloc_swap_scan_cluster(struct swap_info_struct *si, + struct swap_cluster_info *ci, + unsigned long offset, + unsigned int order, + unsigned char usage) { - unsigned long begin = offset; - unsigned long end = offset + nr_entries - 1; - void (*swap_slot_free_notify)(struct block_device *, unsigned long); + unsigned int next = SWAP_ENTRY_INVALID, found = SWAP_ENTRY_INVALID; + unsigned long start = ALIGN_DOWN(offset, SWAPFILE_CLUSTER); + unsigned long end = min(start + SWAPFILE_CLUSTER, si->max); + unsigned int nr_pages = 1 << order; + bool need_reclaim, ret; - if (offset < si->lowest_bit) - si->lowest_bit = offset; - if (end > si->highest_bit) { - bool was_full = !si->highest_bit; + lockdep_assert_held(&ci->lock); - WRITE_ONCE(si->highest_bit, end); - if (was_full && (si->flags & SWP_WRITEOK)) - add_to_avail_list(si); + if (end < nr_pages || ci->count + nr_pages > SWAPFILE_CLUSTER) + goto out; + + for (end -= nr_pages; offset <= end; offset += nr_pages) { + need_reclaim = false; + if (!cluster_scan_range(si, ci, offset, nr_pages, &need_reclaim)) + continue; + if (need_reclaim) { + ret = cluster_reclaim_range(si, ci, offset, offset + nr_pages); + /* + * Reclaim drops ci->lock and cluster could be used + * by another order. Not checking flag as off-list + * cluster has no flag set, and change of list + * won't cause fragmentation. + */ + if (!cluster_is_usable(ci, order)) + goto out; + if (cluster_is_empty(ci)) + offset = start; + /* Reclaim failed but cluster is usable, try next */ + if (!ret) + continue; + } + if (!cluster_alloc_range(si, ci, offset, usage, order)) + break; + found = offset; + offset += nr_pages; + if (ci->count < SWAPFILE_CLUSTER && offset <= end) + next = offset; + break; } - if (si->flags & SWP_BLKDEV) - swap_slot_free_notify = - si->bdev->bd_disk->fops->swap_slot_free_notify; - else - swap_slot_free_notify = NULL; - while (offset <= end) { - arch_swap_invalidate_page(si->type, offset); - if (swap_slot_free_notify) - swap_slot_free_notify(si->bdev, offset); - offset++; +out: + relocate_cluster(si, ci); + unlock_cluster(ci); + if (si->flags & SWP_SOLIDSTATE) { + this_cpu_write(percpu_swap_cluster.offset[order], next); + this_cpu_write(percpu_swap_cluster.si[order], si); + } else { + si->global_cluster->next[order] = next; } - clear_shadow_from_swap_cache(si->type, begin, end); - - /* - * Make sure that try_to_unuse() observes si->inuse_pages reaching 0 - * only after the above cleanups are done. - */ - smp_wmb(); - atomic_long_add(nr_entries, &nr_swap_pages); - WRITE_ONCE(si->inuse_pages, si->inuse_pages - nr_entries); + return found; } -static void set_cluster_next(struct swap_info_struct *si, unsigned long next) +static void swap_reclaim_full_clusters(struct swap_info_struct *si, bool force) { - unsigned long prev; + long to_scan = 1; + unsigned long offset, end; + struct swap_cluster_info *ci; + unsigned char *map = si->swap_map; + int nr_reclaim; + + if (force) + to_scan = swap_usage_in_pages(si) / SWAPFILE_CLUSTER; + + while ((ci = isolate_lock_cluster(si, &si->full_clusters))) { + offset = cluster_offset(si, ci); + end = min(si->max, offset + SWAPFILE_CLUSTER); + to_scan--; + + while (offset < end) { + if (READ_ONCE(map[offset]) == SWAP_HAS_CACHE) { + spin_unlock(&ci->lock); + nr_reclaim = __try_to_reclaim_swap(si, offset, + TTRS_ANYWAY); + spin_lock(&ci->lock); + if (nr_reclaim) { + offset += abs(nr_reclaim); + continue; + } + } + offset++; + } - if (!(si->flags & SWP_SOLIDSTATE)) { - si->cluster_next = next; - return; - } + /* in case no swap cache is reclaimed */ + if (ci->flags == CLUSTER_FLAG_NONE) + relocate_cluster(si, ci); - prev = this_cpu_read(*si->cluster_next_cpu); - /* - * Cross the swap address space size aligned trunk, choose - * another trunk randomly to avoid lock contention on swap - * address space if possible. - */ - if ((prev >> SWAP_ADDRESS_SPACE_SHIFT) != - (next >> SWAP_ADDRESS_SPACE_SHIFT)) { - /* No free swap slots available */ - if (si->highest_bit <= si->lowest_bit) - return; - next = get_random_u32_inclusive(si->lowest_bit, si->highest_bit); - next = ALIGN_DOWN(next, SWAP_ADDRESS_SPACE_PAGES); - next = max_t(unsigned int, next, si->lowest_bit); + unlock_cluster(ci); + if (to_scan <= 0) + break; } - this_cpu_write(*si->cluster_next_cpu, next); } -static bool swap_offset_available_and_locked(struct swap_info_struct *si, - unsigned long offset) +static void swap_reclaim_work(struct work_struct *work) { - if (data_race(!si->swap_map[offset])) { - spin_lock(&si->lock); - return true; - } + struct swap_info_struct *si; - if (vm_swap_full() && READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) { - spin_lock(&si->lock); - return true; - } + si = container_of(work, struct swap_info_struct, reclaim_work); - return false; + swap_reclaim_full_clusters(si, true); } -static int scan_swap_map_slots(struct swap_info_struct *si, - unsigned char usage, int nr, - swp_entry_t slots[]) +/* + * Try to allocate swap entries with specified order and try set a new + * cluster for current CPU too. + */ +static unsigned long cluster_alloc_swap_entry(struct swap_info_struct *si, int order, + unsigned char usage) { struct 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; + unsigned int offset = SWAP_ENTRY_INVALID, found = SWAP_ENTRY_INVALID; /* - * 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 + * Swapfile is not block device so unable + * to allocate large entries. */ + if (order && !(si->flags & SWP_BLKDEV)) + return 0; + + if (!(si->flags & SWP_SOLIDSTATE)) { + /* Serialize HDD SWAP allocation for each device. */ + spin_lock(&si->global_cluster_lock); + offset = si->global_cluster->next[order]; + if (offset == SWAP_ENTRY_INVALID) + goto new_cluster; + + ci = lock_cluster(si, offset); + /* Cluster could have been used by another order */ + if (cluster_is_usable(ci, order)) { + if (cluster_is_empty(ci)) + offset = cluster_offset(si, ci); + found = alloc_swap_scan_cluster(si, ci, offset, + order, usage); + } else { + unlock_cluster(ci); + } + if (found) + goto done; + } + +new_cluster: + ci = isolate_lock_cluster(si, &si->free_clusters); + if (ci) { + found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci), + order, usage); + if (found) + goto done; + } + + /* Try reclaim from full clusters if free clusters list is drained */ + if (vm_swap_full()) + swap_reclaim_full_clusters(si, false); + + if (order < PMD_ORDER) { + unsigned int frags = 0, frags_existing; + + while ((ci = isolate_lock_cluster(si, &si->nonfull_clusters[order]))) { + found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci), + order, usage); + if (found) + goto done; + /* Clusters failed to allocate are moved to frag_clusters */ + frags++; + } + + frags_existing = atomic_long_read(&si->frag_cluster_nr[order]); + while (frags < frags_existing && + (ci = isolate_lock_cluster(si, &si->frag_clusters[order]))) { + atomic_long_dec(&si->frag_cluster_nr[order]); + /* + * Rotate the frag list to iterate, they were all + * failing high order allocation or moved here due to + * per-CPU usage, but they could contain newly released + * reclaimable (eg. lazy-freed swap cache) slots. + */ + found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci), + order, usage); + if (found) + goto done; + frags++; + } + } - 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. + * 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 */ - 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; - } + if ((si->flags & SWP_PAGE_DISCARD) && swap_do_scheduled_discard(si)) + goto new_cluster; - spin_unlock(&si->lock); + if (order) + goto done; + /* Order 0 stealing from higher order */ + for (int o = 1; o < SWAP_NR_ORDERS; o++) { /* - * 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. + * Clusters here have at least one usable slots and can't fail order 0 + * allocation, but reclaim may drop si->lock and race with another user. */ - 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; - } + while ((ci = isolate_lock_cluster(si, &si->frag_clusters[o]))) { + atomic_long_dec(&si->frag_cluster_nr[o]); + found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci), + 0, usage); + if (found) + goto done; } - 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) + while ((ci = isolate_lock_cluster(si, &si->nonfull_clusters[o]))) { + found = alloc_swap_scan_cluster(si, ci, cluster_offset(si, ci), + 0, usage); + if (found) 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; +done: + if (!(si->flags & SWP_SOLIDSTATE)) + spin_unlock(&si->global_cluster_lock); + return found; +} - 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 */ - } +/* SWAP_USAGE_OFFLIST_BIT can only be set by this helper. */ +static void del_from_avail_list(struct swap_info_struct *si, bool swapoff) +{ + int nid; + unsigned long pages; - if (si->swap_map[offset]) { - unlock_cluster(ci); - if (!n_ret) - goto scan; - else - goto done; + spin_lock(&swap_avail_lock); + + if (swapoff) { + /* + * Forcefully remove it. Clear the SWP_WRITEOK flags for + * swapoff here so it's synchronized by both si->lock and + * swap_avail_lock, to ensure the result can be seen by + * add_to_avail_list. + */ + lockdep_assert_held(&si->lock); + si->flags &= ~SWP_WRITEOK; + atomic_long_or(SWAP_USAGE_OFFLIST_BIT, &si->inuse_pages); + } else { + /* + * If not called by swapoff, take it off-list only if it's + * full and SWAP_USAGE_OFFLIST_BIT is not set (strictly + * si->inuse_pages == pages), any concurrent slot freeing, + * or device already removed from plist by someone else + * will make this return false. + */ + pages = si->pages; + if (!atomic_long_try_cmpxchg(&si->inuse_pages, &pages, + pages | SWAP_USAGE_OFFLIST_BIT)) + goto skip; } - 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); + for_each_node(nid) + plist_del(&si->avail_lists[nid], &swap_avail_heads[nid]); - /* got enough slots or reach max slots? */ - if ((n_ret == nr) || (offset >= si->highest_bit)) - goto done; +skip: + spin_unlock(&swap_avail_lock); +} - /* search for next available slot */ +/* SWAP_USAGE_OFFLIST_BIT can only be cleared by this helper. */ +static void add_to_avail_list(struct swap_info_struct *si, bool swapon) +{ + int nid; + long val; + unsigned long pages; - /* 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; - } + spin_lock(&swap_avail_lock); - /* 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; + /* Corresponding to SWP_WRITEOK clearing in del_from_avail_list */ + if (swapon) { + lockdep_assert_held(&si->lock); + si->flags |= SWP_WRITEOK; + } else { + if (!(READ_ONCE(si->flags) & SWP_WRITEOK)) + goto skip; } + if (!(atomic_long_read(&si->inuse_pages) & SWAP_USAGE_OFFLIST_BIT)) + goto skip; + + val = atomic_long_fetch_and_relaxed(~SWAP_USAGE_OFFLIST_BIT, &si->inuse_pages); + /* - * 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. + * When device is full and device is on the plist, only one updater will + * see (inuse_pages == si->pages) and will call del_from_avail_list. If + * that updater happen to be here, just skip adding. */ - 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; - } + pages = si->pages; + if (val == pages) { + /* Just like the cmpxchg in del_from_avail_list */ + if (atomic_long_try_cmpxchg(&si->inuse_pages, &pages, + pages | SWAP_USAGE_OFFLIST_BIT)) + goto skip; } -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); + for_each_node(nid) + plist_add(&si->avail_lists[nid], &swap_avail_heads[nid]); -no_page: - si->flags -= SWP_SCANNING; - return n_ret; +skip: + spin_unlock(&swap_avail_lock); } -static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) +/* + * swap_usage_add / swap_usage_sub of each slot are serialized by ci->lock + * within each cluster, so the total contribution to the global counter should + * always be positive and cannot exceed the total number of usable slots. + */ +static bool swap_usage_add(struct swap_info_struct *si, unsigned int nr_entries) { - unsigned long idx; - struct swap_cluster_info *ci; - unsigned long offset; + long val = atomic_long_add_return_relaxed(nr_entries, &si->inuse_pages); /* - * Should not even be attempting cluster allocations when huge - * page swap is disabled. Warn and fail the allocation. + * If device is full, and SWAP_USAGE_OFFLIST_BIT is not set, + * remove it from the plist. */ - if (!IS_ENABLED(CONFIG_THP_SWAP)) { - VM_WARN_ON_ONCE(1); - return 0; + if (unlikely(val == si->pages)) { + del_from_avail_list(si, false); + return true; } - if (cluster_list_empty(&si->free_clusters)) - return 0; + return false; +} - 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); +static void swap_usage_sub(struct swap_info_struct *si, unsigned int nr_entries) +{ + long val = atomic_long_sub_return_relaxed(nr_entries, &si->inuse_pages); - 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); + /* + * If device is not full, and SWAP_USAGE_OFFLIST_BIT is set, + * add it to the plist. + */ + if (unlikely(val & SWAP_USAGE_OFFLIST_BIT)) + add_to_avail_list(si, false); +} - return 1; +static void swap_range_alloc(struct swap_info_struct *si, + unsigned int nr_entries) +{ + if (swap_usage_add(si, nr_entries)) { + if (vm_swap_full()) + schedule_work(&si->reclaim_work); + } } -static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) +static void swap_range_free(struct swap_info_struct *si, unsigned long offset, + unsigned int nr_entries) { - unsigned long offset = idx * SWAPFILE_CLUSTER; - struct swap_cluster_info *ci; + unsigned long begin = offset; + unsigned long end = offset + nr_entries - 1; + void (*swap_slot_free_notify)(struct block_device *, unsigned long); + unsigned int i; - 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); + /* + * Use atomic clear_bit operations only on zeromap instead of non-atomic + * bitmap_clear to prevent adjacent bits corruption due to simultaneous writes. + */ + for (i = 0; i < nr_entries; i++) { + clear_bit(offset + i, si->zeromap); + zswap_invalidate(swp_entry(si->type, offset + i)); + } + + if (si->flags & SWP_BLKDEV) + swap_slot_free_notify = + si->bdev->bd_disk->fops->swap_slot_free_notify; + else + swap_slot_free_notify = NULL; + while (offset <= end) { + arch_swap_invalidate_page(si->type, offset); + if (swap_slot_free_notify) + swap_slot_free_notify(si->bdev, offset); + offset++; + } + clear_shadow_from_swap_cache(si->type, begin, end); + + /* + * Make sure that try_to_unuse() observes si->inuse_pages reaching 0 + * only after the above cleanups are done. + */ + smp_wmb(); + atomic_long_add(nr_entries, &nr_swap_pages); + swap_usage_sub(si, nr_entries); } -int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size) +static bool get_swap_device_info(struct swap_info_struct *si) { - unsigned long size = swap_entry_size(entry_size); - struct swap_info_struct *si, *next; - long avail_pgs; - int n_ret = 0; - int node; + if (!percpu_ref_tryget_live(&si->users)) + return false; + /* + * Guarantee the si->users are checked before accessing other + * fields of swap_info_struct, and si->flags (SWP_WRITEOK) is + * up to dated. + * + * Paired with the spin_unlock() after setup_swap_info() in + * enable_swap_info(), and smp_wmb() in swapoff. + */ + smp_rmb(); + return true; +} - /* Only single cluster request supported */ - WARN_ON_ONCE(n_goal > 1 && size == SWAPFILE_CLUSTER); +/* + * Fast path try to get swap entries with specified order from current + * CPU's swap entry pool (a cluster). + */ +static bool swap_alloc_fast(swp_entry_t *entry, + int order) +{ + struct swap_cluster_info *ci; + struct swap_info_struct *si; + unsigned int offset, found = SWAP_ENTRY_INVALID; - spin_lock(&swap_avail_lock); + /* + * Once allocated, swap_info_struct will never be completely freed, + * so checking it's liveness by get_swap_device_info is enough. + */ + si = this_cpu_read(percpu_swap_cluster.si[order]); + offset = this_cpu_read(percpu_swap_cluster.offset[order]); + if (!si || !offset || !get_swap_device_info(si)) + return false; - avail_pgs = atomic_long_read(&nr_swap_pages) / size; - if (avail_pgs <= 0) { - spin_unlock(&swap_avail_lock); - goto noswap; + ci = lock_cluster(si, offset); + if (cluster_is_usable(ci, order)) { + if (cluster_is_empty(ci)) + offset = cluster_offset(si, ci); + found = alloc_swap_scan_cluster(si, ci, offset, order, SWAP_HAS_CACHE); + if (found) + *entry = swp_entry(si->type, found); + } else { + unlock_cluster(ci); } - n_goal = min3((long)n_goal, (long)SWAP_BATCH, avail_pgs); + put_swap_device(si); + return !!found; +} - atomic_long_sub(n_goal * size, &nr_swap_pages); +/* Rotate the device and switch to a new cluster */ +static bool swap_alloc_slow(swp_entry_t *entry, + int order) +{ + int node; + unsigned long offset; + struct swap_info_struct *si, *next; -start_over: node = numa_node_id(); + spin_lock(&swap_avail_lock); +start_over: plist_for_each_entry_safe(si, next, &swap_avail_heads[node], avail_lists[node]) { - /* requeue si to after same-priority siblings */ + /* Rotate the device and switch to a new cluster */ 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; + if (get_swap_device_info(si)) { + offset = cluster_alloc_swap_entry(si, order, SWAP_HAS_CACHE); + put_swap_device(si); + if (offset) { + *entry = swp_entry(si->type, offset); + return true; } - 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 (order) + return false; } - 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; - 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, @@ -1123,35 +1248,97 @@ nextsi: if (plist_node_empty(&next->avail_lists[node])) goto start_over; } - spin_unlock(&swap_avail_lock); + return false; +} + +/** + * folio_alloc_swap - allocate swap space for a folio + * @folio: folio we want to move to swap + * @gfp: gfp mask for shadow nodes + * + * Allocate swap space for the folio and add the folio to the + * swap cache. + * + * Context: Caller needs to hold the folio lock. + * Return: Whether the folio was added to the swap cache. + */ +int folio_alloc_swap(struct folio *folio, gfp_t gfp) +{ + unsigned int order = folio_order(folio); + unsigned int size = 1 << order; + swp_entry_t entry = {}; + + VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); + VM_BUG_ON_FOLIO(!folio_test_uptodate(folio), folio); + + if (order) { + /* + * Reject large allocation when THP_SWAP is disabled, + * the caller should split the folio and try again. + */ + if (!IS_ENABLED(CONFIG_THP_SWAP)) + return -EAGAIN; + + /* + * Allocation size should never exceed cluster size + * (HPAGE_PMD_SIZE). + */ + if (size > SWAPFILE_CLUSTER) { + VM_WARN_ON_ONCE(1); + return -EINVAL; + } + } + + local_lock(&percpu_swap_cluster.lock); + if (!swap_alloc_fast(&entry, order)) + swap_alloc_slow(&entry, order); + local_unlock(&percpu_swap_cluster.lock); + + /* Need to call this even if allocation failed, for MEMCG_SWAP_FAIL. */ + if (mem_cgroup_try_charge_swap(folio, entry)) + goto out_free; + + if (!entry.val) + return -ENOMEM; -check_out: - if (n_ret < n_goal) - atomic_long_add((long)(n_goal - n_ret) * size, - &nr_swap_pages); -noswap: - return n_ret; + /* + * XArray node allocations from PF_MEMALLOC contexts could + * completely exhaust the page allocator. __GFP_NOMEMALLOC + * stops emergency reserves from being allocated. + * + * TODO: this could cause a theoretical memory reclaim + * deadlock in the swap out path. + */ + if (add_to_swap_cache(folio, entry, gfp | __GFP_NOMEMALLOC, NULL)) + goto out_free; + + atomic_long_sub(size, &nr_swap_pages); + return 0; + +out_free: + put_swap_folio(folio, entry); + return -ENOMEM; } static struct swap_info_struct *_swap_info_get(swp_entry_t entry) { - struct swap_info_struct *p; + struct swap_info_struct *si; unsigned long offset; if (!entry.val) goto out; - p = swp_swap_info(entry); - if (!p) + si = swp_swap_info(entry); + if (!si) goto bad_nofile; - if (data_race(!(p->flags & SWP_USED))) + if (data_race(!(si->flags & SWP_USED))) goto bad_device; offset = swp_offset(entry); - if (offset >= p->max) + if (offset >= si->max) goto bad_offset; - if (data_race(!p->swap_map[swp_offset(entry)])) + if (data_race(!si->swap_map[swp_offset(entry)])) goto bad_free; - return p; + return si; bad_free: pr_err("%s: %s%08lx\n", __func__, Unused_offset, entry.val); @@ -1168,30 +1355,16 @@ 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) +static unsigned char swap_entry_put_locked(struct swap_info_struct *si, + struct swap_cluster_info *ci, + swp_entry_t entry, + unsigned char usage) { + unsigned long offset = swp_offset(entry); unsigned char count; unsigned char has_cache; - count = p->swap_map[offset]; + count = si->swap_map[offset]; has_cache = count & SWAP_HAS_CACHE; count &= ~SWAP_HAS_CACHE; @@ -1207,7 +1380,7 @@ static unsigned char __swap_entry_free_locked(struct swap_info_struct *p, count = 0; } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { if (count == COUNT_CONTINUED) { - if (swap_count_continued(p, offset, count)) + if (swap_count_continued(si, offset, count)) count = SWAP_MAP_MAX | COUNT_CONTINUED; else count = SWAP_MAP_MAX; @@ -1217,25 +1390,24 @@ static unsigned char __swap_entry_free_locked(struct swap_info_struct *p, usage = count | has_cache; if (usage) - WRITE_ONCE(p->swap_map[offset], usage); + WRITE_ONCE(si->swap_map[offset], usage); else - WRITE_ONCE(p->swap_map[offset], SWAP_HAS_CACHE); + swap_entries_free(si, ci, entry, 1); return usage; } /* * When we get a swap entry, if there aren't some other ways to - * prevent swapoff, such as the folio in swap cache is locked, page - * table lock is held, etc., the swap entry may become invalid because - * of swapoff. Then, we need to enclose all swap related functions - * with get_swap_device() and put_swap_device(), unless the swap - * functions call get/put_swap_device() by themselves. + * prevent swapoff, such as the folio in swap cache is locked, RCU + * reader side is locked, etc., the swap entry may become invalid + * because of swapoff. Then, we need to enclose all swap related + * functions with get_swap_device() and put_swap_device(), unless the + * swap functions call get/put_swap_device() by themselves. * - * Note that when only holding the PTL, swapoff might succeed immediately - * after freeing a swap entry. Therefore, immediately after - * __swap_entry_free(), the swap info might become stale and should not - * be touched without a prior get_swap_device(). + * RCU reader side lock (including any spinlock) is sufficient to + * prevent swapoff, because synchronize_rcu() is called in swapoff() + * before freeing data structures. * * Check whether swap entry is valid in the swap device. If so, * return pointer to swap_info_struct, and keep the swap entry valid @@ -1274,16 +1446,8 @@ struct swap_info_struct *get_swap_device(swp_entry_t entry) si = swp_swap_info(entry); if (!si) goto bad_nofile; - if (!percpu_ref_tryget_live(&si->users)) + if (!get_swap_device_info(si)) 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; @@ -1299,152 +1463,164 @@ put_out: return NULL; } -static unsigned char __swap_entry_free(struct swap_info_struct *p, - swp_entry_t entry) +static void swap_entries_put_cache(struct swap_info_struct *si, + swp_entry_t entry, int nr) { - 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); + struct swap_cluster_info *ci; - return usage; + ci = lock_cluster(si, offset); + if (swap_only_has_cache(si, offset, nr)) + swap_entries_free(si, ci, entry, nr); + else { + for (int i = 0; i < nr; i++, entry.val++) + swap_entry_put_locked(si, ci, entry, SWAP_HAS_CACHE); + } + unlock_cluster(ci); } -static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry) +static bool swap_entries_put_map(struct swap_info_struct *si, + swp_entry_t entry, int nr) { - struct swap_cluster_info *ci; unsigned long offset = swp_offset(entry); + struct swap_cluster_info *ci; + bool has_cache = false; unsigned char count; + int i; + + if (nr <= 1) + goto fallback; + count = swap_count(data_race(si->swap_map[offset])); + if (count != 1 && count != SWAP_MAP_SHMEM) + goto fallback; - 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); + ci = lock_cluster(si, offset); + if (!swap_is_last_map(si, offset, nr, &has_cache)) { + goto locked_fallback; + } + if (!has_cache) + swap_entries_free(si, ci, entry, nr); + else + for (i = 0; i < nr; i++) + WRITE_ONCE(si->swap_map[offset + i], SWAP_HAS_CACHE); unlock_cluster(ci); - mem_cgroup_uncharge_swap(entry, 1); - swap_range_free(p, offset, 1); + return has_cache; + +fallback: + ci = lock_cluster(si, offset); +locked_fallback: + for (i = 0; i < nr; i++, entry.val++) { + count = swap_entry_put_locked(si, ci, entry, 1); + if (count == SWAP_HAS_CACHE) + has_cache = true; + } + unlock_cluster(ci); + return has_cache; + } /* - * Caller has made sure that the swap device corresponding to entry - * is still around or has not been recycled. + * Only functions with "_nr" suffix are able to free entries spanning + * cross multi clusters, so ensure the range is within a single cluster + * when freeing entries with functions without "_nr" suffix. */ -void swap_free(swp_entry_t entry) +static bool swap_entries_put_map_nr(struct swap_info_struct *si, + swp_entry_t entry, int nr) { - struct swap_info_struct *p; + int cluster_nr, cluster_rest; + unsigned long offset = swp_offset(entry); + bool has_cache = false; + + cluster_rest = SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER; + while (nr) { + cluster_nr = min(nr, cluster_rest); + has_cache |= swap_entries_put_map(si, entry, cluster_nr); + cluster_rest = SWAPFILE_CLUSTER; + nr -= cluster_nr; + entry.val += cluster_nr; + } - p = _swap_info_get(entry); - if (p) - __swap_entry_free(p, entry); + return has_cache; } /* - * Called after dropping swapcache to decrease refcnt to swap entries. + * Check if it's the last ref of swap entry in the freeing path. + * Qualified vlaue includes 1, SWAP_HAS_CACHE or SWAP_MAP_SHMEM. */ -void put_swap_folio(struct folio *folio, swp_entry_t entry) +static inline bool __maybe_unused swap_is_last_ref(unsigned char count) { - 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); + return (count == SWAP_HAS_CACHE) || (count == 1) || + (count == SWAP_MAP_SHMEM); } -#ifdef CONFIG_THP_SWAP -int split_swap_cluster(swp_entry_t entry) +/* + * Drop the last ref of swap entries, caller have to ensure all entries + * belong to the same cgroup and cluster. + */ +static void swap_entries_free(struct swap_info_struct *si, + struct swap_cluster_info *ci, + swp_entry_t entry, unsigned int nr_pages) { - struct swap_info_struct *si; - struct swap_cluster_info *ci; unsigned long offset = swp_offset(entry); + unsigned char *map = si->swap_map + offset; + unsigned char *map_end = map + nr_pages; - si = _swap_info_get(entry); - if (!si) - return -EBUSY; - ci = lock_cluster(si, offset); - cluster_clear_huge(ci); - unlock_cluster(ci); - return 0; + /* It should never free entries across different clusters */ + VM_BUG_ON(ci != offset_to_cluster(si, offset + nr_pages - 1)); + VM_BUG_ON(cluster_is_empty(ci)); + VM_BUG_ON(ci->count < nr_pages); + + ci->count -= nr_pages; + do { + VM_BUG_ON(!swap_is_last_ref(*map)); + *map = 0; + } while (++map < map_end); + + mem_cgroup_uncharge_swap(entry, nr_pages); + swap_range_free(si, offset, nr_pages); + + if (!ci->count) + free_cluster(si, ci); + else + partial_free_cluster(si, ci); } -#endif -static int swp_entry_cmp(const void *ent1, const void *ent2) +/* + * Caller has made sure that the swap device corresponding to entry + * is still around or has not been recycled. + */ +void swap_free_nr(swp_entry_t entry, int nr_pages) { - const swp_entry_t *e1 = ent1, *e2 = ent2; + int nr; + struct swap_info_struct *sis; + unsigned long offset = swp_offset(entry); - return (int)swp_type(*e1) - (int)swp_type(*e2); + sis = _swap_info_get(entry); + if (!sis) + return; + + while (nr_pages) { + nr = min_t(int, nr_pages, SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER); + swap_entries_put_map(sis, swp_entry(sis->type, offset), nr); + offset += nr; + nr_pages -= nr; + } } -void swapcache_free_entries(swp_entry_t *entries, int n) +/* + * Called after dropping swapcache to decrease refcnt to swap entries. + */ +void put_swap_folio(struct folio *folio, swp_entry_t entry) { - struct swap_info_struct *p, *prev; - int i; + struct swap_info_struct *si; + int size = 1 << swap_entry_order(folio_order(folio)); - if (n <= 0) + si = _swap_info_get(entry); + if (!si) 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); + swap_entries_put_cache(si, entry, size); } int __swap_count(swp_entry_t entry) @@ -1460,16 +1636,16 @@ int __swap_count(swp_entry_t entry) * This does not give an exact answer when swap count is continued, * but does include the high COUNT_CONTINUED flag to allow for that. */ -int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry) +bool swap_entry_swapped(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); + ci = lock_cluster(si, offset); count = swap_count(si->swap_map[offset]); - unlock_cluster_or_swap_info(si, ci); - return count; + unlock_cluster(ci); + return !!count; } /* @@ -1479,28 +1655,28 @@ int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry) int swp_swapcount(swp_entry_t entry) { int count, tmp_count, n; - struct swap_info_struct *p; + struct swap_info_struct *si; struct swap_cluster_info *ci; struct page *page; pgoff_t offset; unsigned char *map; - p = _swap_info_get(entry); - if (!p) + si = _swap_info_get(entry); + if (!si) return 0; offset = swp_offset(entry); - ci = lock_cluster_or_swap_info(p, offset); + ci = lock_cluster(si, offset); - count = swap_count(p->swap_map[offset]); + count = swap_count(si->swap_map[offset]); if (!(count & COUNT_CONTINUED)) goto out; count &= ~COUNT_CONTINUED; n = SWAP_MAP_MAX + 1; - page = vmalloc_to_page(p->swap_map + offset); + page = vmalloc_to_page(si->swap_map + offset); offset &= ~PAGE_MASK; VM_BUG_ON(page_private(page) != SWP_CONTINUED); @@ -1514,34 +1690,35 @@ int swp_swapcount(swp_entry_t entry) n *= (SWAP_CONT_MAX + 1); } while (tmp_count & COUNT_CONTINUED); out: - unlock_cluster_or_swap_info(p, ci); + unlock_cluster(ci); return count; } static bool swap_page_trans_huge_swapped(struct swap_info_struct *si, - swp_entry_t entry) + swp_entry_t entry, int order) { struct swap_cluster_info *ci; unsigned char *map = si->swap_map; + unsigned int nr_pages = 1 << order; unsigned long roffset = swp_offset(entry); - unsigned long offset = round_down(roffset, SWAPFILE_CLUSTER); + unsigned long offset = round_down(roffset, nr_pages); int i; bool ret = false; - ci = lock_cluster_or_swap_info(si, offset); - if (!ci || !cluster_is_huge(ci)) { + ci = lock_cluster(si, offset); + if (nr_pages == 1) { if (swap_count(map[roffset])) ret = true; goto unlock_out; } - for (i = 0; i < SWAPFILE_CLUSTER; i++) { + for (i = 0; i < nr_pages; i++) { if (swap_count(map[offset + i])) { ret = true; break; } } unlock_out: - unlock_cluster_or_swap_info(si, ci); + unlock_cluster(ci); return ret; } @@ -1554,21 +1731,12 @@ static bool folio_swapped(struct folio *folio) return false; if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!folio_test_large(folio))) - return swap_swapcount(si, entry) != 0; + return swap_entry_swapped(si, entry); - return swap_page_trans_huge_swapped(si, entry); + return swap_page_trans_huge_swapped(si, entry, folio_order(folio)); } -/** - * 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) +static bool folio_swapcache_freeable(struct folio *folio) { VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio); @@ -1576,8 +1744,6 @@ bool folio_free_swap(struct folio *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, @@ -1597,38 +1763,93 @@ bool folio_free_swap(struct folio *folio) if (pm_suspended_storage()) return false; + return true; +} + +/** + * folio_free_swap() - Free the swap space used for this folio. + * @folio: The folio to remove. + * + * If swap is getting full, or if there are no more mappings of this folio, + * then call folio_free_swap to free its swap space. + * + * Return: true if we were able to release the swap space. + */ +bool folio_free_swap(struct folio *folio) +{ + if (!folio_swapcache_freeable(folio)) + return false; + if (folio_swapped(folio)) + return false; + delete_from_swap_cache(folio); folio_set_dirty(folio); return true; } -/* - * Free the swap entry like above, but also try to - * free the page cache entry if it is the last user. +/** + * free_swap_and_cache_nr() - Release reference on range of swap entries and + * reclaim their cache if no more references remain. + * @entry: First entry of range. + * @nr: Number of entries in range. + * + * For each swap entry in the contiguous range, release a reference. If any swap + * entries become free, try to reclaim their underlying folios, if present. The + * offset range is defined by [entry.offset, entry.offset + nr). */ -int free_swap_and_cache(swp_entry_t entry) +void free_swap_and_cache_nr(swp_entry_t entry, int nr) { - struct swap_info_struct *p; - unsigned char count; + const unsigned long start_offset = swp_offset(entry); + const unsigned long end_offset = start_offset + nr; + struct swap_info_struct *si; + bool any_only_cache = false; + unsigned long offset; - if (non_swap_entry(entry)) - return 1; + si = get_swap_device(entry); + if (!si) + return; - p = get_swap_device(entry); - if (p) { - if (WARN_ON(data_race(!p->swap_map[swp_offset(entry)]))) { - put_swap_device(p); - return 0; - } + if (WARN_ON(end_offset > si->max)) + goto out; + + /* + * First free all entries in the range. + */ + any_only_cache = swap_entries_put_map_nr(si, entry, nr); - 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); - put_swap_device(p); + /* + * Short-circuit the below loop if none of the entries had their + * reference drop to zero. + */ + if (!any_only_cache) + goto out; + + /* + * Now go back over the range trying to reclaim the swap cache. + */ + for (offset = start_offset; offset < end_offset; offset += nr) { + nr = 1; + if (READ_ONCE(si->swap_map[offset]) == SWAP_HAS_CACHE) { + /* + * Folios are always naturally aligned in swap so + * advance forward to the next boundary. Zero means no + * folio was found for the swap entry, so advance by 1 + * in this case. Negative value means folio was found + * but could not be reclaimed. Here we can still advance + * to the next boundary. + */ + nr = __try_to_reclaim_swap(si, offset, + TTRS_UNMAPPED | TTRS_FULL); + if (nr == 0) + nr = 1; + else if (nr < 0) + nr = -nr; + nr = ALIGN(offset + 1, nr) - offset; + } } - return p != NULL; + +out: + put_swap_device(si); } #ifdef CONFIG_HIBERNATION @@ -1636,16 +1857,23 @@ int free_swap_and_cache(swp_entry_t entry) swp_entry_t get_swap_page_of_type(int type) { struct swap_info_struct *si = swap_type_to_swap_info(type); + unsigned long offset; 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); + if (get_swap_device_info(si)) { + if (si->flags & SWP_WRITEOK) { + offset = cluster_alloc_swap_entry(si, 0, 1); + if (offset) { + entry = swp_entry(si->type, offset); + atomic_long_dec(&nr_swap_pages); + } + } + put_swap_device(si); + } fail: return entry; } @@ -1736,7 +1964,7 @@ unsigned int count_swap_pages(int type, int free) if (sis->flags & SWP_WRITEOK) { n = sis->pages; if (free) - n -= sis->inuse_pages; + n -= swap_usage_in_pages(sis); } spin_unlock(&sis->lock); } @@ -1806,7 +2034,7 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, * when reading from swap. This metadata may be indexed by swap entry * so this must be called before swap_free(). */ - arch_swap_restore(entry, folio); + arch_swap_restore(folio_swap(entry, folio), folio); dec_mm_counter(vma->vm_mm, MM_SWAPENTS); inc_mm_counter(vma->vm_mm, MM_ANONPAGES); @@ -1822,10 +2050,20 @@ static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, VM_BUG_ON_FOLIO(folio_test_writeback(folio), folio); if (pte_swp_exclusive(old_pte)) rmap_flags |= RMAP_EXCLUSIVE; - - folio_add_anon_rmap_pte(folio, page, vma, addr, rmap_flags); + /* + * We currently only expect small !anon folios, which are either + * fully exclusive or fully shared. If we ever get large folios + * here, we have to be careful. + */ + if (!folio_test_anon(folio)) { + VM_WARN_ON_ONCE(folio_test_large(folio)); + VM_WARN_ON_FOLIO(!folio_test_locked(folio), folio); + folio_add_new_anon_rmap(folio, vma, addr, rmap_flags); + } else { + folio_add_anon_rmap_pte(folio, page, vma, addr, rmap_flags); + } } else { /* ksm created a completely new copy */ - folio_add_new_anon_rmap(folio, vma, addr); + folio_add_new_anon_rmap(folio, vma, addr, RMAP_EXCLUSIVE); folio_add_lru_vma(folio, vma); } new_pte = pte_mkold(mk_pte(page, vma->vm_page_prot)); @@ -1883,7 +2121,6 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, folio = swap_cache_get_folio(entry, vma, addr); if (!folio) { - struct page *page; struct vm_fault vmf = { .vma = vma, .address = addr, @@ -1891,10 +2128,8 @@ static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, .pmd = pmd, }; - page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, + folio = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, &vmf); - if (page) - folio = page_folio(page); } if (!folio) { swp_count = READ_ONCE(si->swap_map[offset]); @@ -2010,7 +2245,7 @@ static int unuse_mm(struct mm_struct *mm, unsigned int type) mmap_read_lock(mm); for_each_vma(vmi, vma) { - if (vma->anon_vma) { + if (vma->anon_vma && !is_vm_hugetlb_page(vma)) { ret = unuse_vma(vma, type); if (ret) break; @@ -2064,7 +2299,7 @@ static int try_to_unuse(unsigned int type) swp_entry_t entry; unsigned int i; - if (!READ_ONCE(si->inuse_pages)) + if (!swap_usage_in_pages(si)) goto success; retry: @@ -2077,7 +2312,7 @@ retry: spin_lock(&mmlist_lock); p = &init_mm.mmlist; - while (READ_ONCE(si->inuse_pages) && + while (swap_usage_in_pages(si) && !signal_pending(current) && (p = p->next) != &init_mm.mmlist) { @@ -2105,12 +2340,12 @@ retry: mmput(prev_mm); i = 0; - while (READ_ONCE(si->inuse_pages) && + while (swap_usage_in_pages(si) && !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); + folio = filemap_get_folio(swap_address_space(entry), swap_cache_index(entry)); if (IS_ERR(folio)) continue; @@ -2136,11 +2371,11 @@ retry: * 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 + * and even shmem_writeout() 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 (swap_usage_in_pages(si)) { if (!signal_pending(current)) goto retry; return -EINTR; @@ -2167,7 +2402,7 @@ static void drain_mmlist(void) unsigned int type; for (type = 0; type < nr_swapfiles; type++) - if (swap_info[type]->inuse_pages) + if (swap_usage_in_pages(swap_info[type])) return; spin_lock(&mmlist_lock); list_for_each_safe(p, next, &init_mm.mmlist) @@ -2301,52 +2536,53 @@ static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) return generic_swapfile_activate(sis, swap_file, span); } -static int swap_node(struct swap_info_struct *p) +static int swap_node(struct swap_info_struct *si) { struct block_device *bdev; - if (p->bdev) - bdev = p->bdev; + if (si->bdev) + bdev = si->bdev; else - bdev = p->swap_file->f_inode->i_sb->s_bdev; + bdev = si->swap_file->f_inode->i_sb->s_bdev; return bdev ? bdev->bd_disk->node_id : NUMA_NO_NODE; } -static void setup_swap_info(struct swap_info_struct *p, int prio, +static void setup_swap_info(struct swap_info_struct *si, int prio, unsigned char *swap_map, - struct swap_cluster_info *cluster_info) + struct swap_cluster_info *cluster_info, + unsigned long *zeromap) { int i; if (prio >= 0) - p->prio = prio; + si->prio = prio; else - p->prio = --least_priority; + si->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; + si->list.prio = -si->prio; for_each_node(i) { - if (p->prio >= 0) - p->avail_lists[i].prio = -p->prio; + if (si->prio >= 0) + si->avail_lists[i].prio = -si->prio; else { - if (swap_node(p) == i) - p->avail_lists[i].prio = 1; + if (swap_node(si) == i) + si->avail_lists[i].prio = 1; else - p->avail_lists[i].prio = -p->prio; + si->avail_lists[i].prio = -si->prio; } } - p->swap_map = swap_map; - p->cluster_info = cluster_info; + si->swap_map = swap_map; + si->cluster_info = cluster_info; + si->zeromap = zeromap; } -static void _enable_swap_info(struct swap_info_struct *p) +static void _enable_swap_info(struct swap_info_struct *si) { - p->flags |= SWP_WRITEOK; - atomic_long_add(p->pages, &nr_swap_pages); - total_swap_pages += p->pages; + atomic_long_add(si->pages, &nr_swap_pages); + total_swap_pages += si->pages; assert_spin_locked(&swap_lock); /* @@ -2359,65 +2595,94 @@ static void _enable_swap_info(struct swap_info_struct *p) * which allocates swap pages from the highest available priority * swap_info_struct. */ - plist_add(&p->list, &swap_active_head); + plist_add(&si->list, &swap_active_head); - /* add to available list iff swap device is not full */ - if (p->highest_bit) - add_to_avail_list(p); + /* Add back to available list */ + add_to_avail_list(si, true); } -static void enable_swap_info(struct swap_info_struct *p, int prio, +static void enable_swap_info(struct swap_info_struct *si, int prio, unsigned char *swap_map, - struct swap_cluster_info *cluster_info) + struct swap_cluster_info *cluster_info, + unsigned long *zeromap) { spin_lock(&swap_lock); - spin_lock(&p->lock); - setup_swap_info(p, prio, swap_map, cluster_info); - spin_unlock(&p->lock); + spin_lock(&si->lock); + setup_swap_info(si, prio, swap_map, cluster_info, zeromap); + spin_unlock(&si->lock); spin_unlock(&swap_lock); /* * Finished initializing swap device, now it's safe to reference it. */ - percpu_ref_resurrect(&p->users); + percpu_ref_resurrect(&si->users); spin_lock(&swap_lock); - spin_lock(&p->lock); - _enable_swap_info(p); - spin_unlock(&p->lock); + spin_lock(&si->lock); + _enable_swap_info(si); + spin_unlock(&si->lock); spin_unlock(&swap_lock); } -static void reinsert_swap_info(struct swap_info_struct *p) +static void reinsert_swap_info(struct swap_info_struct *si) { 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_lock(&si->lock); + setup_swap_info(si, si->prio, si->swap_map, si->cluster_info, si->zeromap); + _enable_swap_info(si); + spin_unlock(&si->lock); spin_unlock(&swap_lock); } -bool has_usable_swap(void) +/* + * Called after clearing SWP_WRITEOK, ensures cluster_alloc_range + * see the updated flags, so there will be no more allocations. + */ +static void wait_for_allocation(struct swap_info_struct *si) { - bool ret = true; + unsigned long offset; + unsigned long end = ALIGN(si->max, SWAPFILE_CLUSTER); + struct swap_cluster_info *ci; - spin_lock(&swap_lock); - if (plist_head_empty(&swap_active_head)) - ret = false; - spin_unlock(&swap_lock); - return ret; + BUG_ON(si->flags & SWP_WRITEOK); + + for (offset = 0; offset < end; offset += SWAPFILE_CLUSTER) { + ci = lock_cluster(si, offset); + unlock_cluster(ci); + } } +/* + * Called after swap device's reference count is dead, so + * neither scan nor allocation will use it. + */ +static void flush_percpu_swap_cluster(struct swap_info_struct *si) +{ + int cpu, i; + struct swap_info_struct **pcp_si; + + for_each_possible_cpu(cpu) { + pcp_si = per_cpu_ptr(percpu_swap_cluster.si, cpu); + /* + * Invalidate the percpu swap cluster cache, si->users + * is dead, so no new user will point to it, just flush + * any existing user. + */ + for (i = 0; i < SWAP_NR_ORDERS; i++) + cmpxchg(&pcp_si[i], si, NULL); + } +} + + SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) { struct swap_info_struct *p = NULL; unsigned char *swap_map; + unsigned long *zeromap; struct swap_cluster_info *cluster_info; struct file *swap_file, *victim; struct address_space *mapping; struct inode *inode; struct filename *pathname; int err, found = 0; - unsigned int old_block_size; if (!capable(CAP_SYS_ADMIN)) return -EPERM; @@ -2456,7 +2721,7 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) goto out_dput; } spin_lock(&p->lock); - del_from_avail_list(p); + del_from_avail_list(p, true); if (p->prio < 0) { struct swap_info_struct *si = p; int nid; @@ -2474,11 +2739,10 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) 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(); + wait_for_allocation(p); set_current_oom_origin(); err = try_to_unuse(p->type); @@ -2487,24 +2751,24 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) 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. + * to complete. Because of synchronize_rcu() here, all swap + * operations protected by RCU reader side lock (including any + * spinlock) will be waited too. This makes it easy to + * prevent folio_test_swapcache() and the following swap cache + * operations from racing with swapoff. */ percpu_ref_kill(&p->users); synchronize_rcu(); wait_for_completion(&p->comp); flush_work(&p->discard_work); + flush_work(&p->reclaim_work); + flush_percpu_swap_cluster(p); destroy_swap_extents(p); if (p->flags & SWP_CONTINUED) @@ -2518,22 +2782,13 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) 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; + zeromap = p->zeromap; + p->zeromap = NULL; cluster_info = p->cluster_info; p->cluster_info = NULL; spin_unlock(&p->lock); @@ -2541,22 +2796,16 @@ SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) arch_swap_invalidate_area(p->type); zswap_swapoff(p->type); mutex_unlock(&swapon_mutex); - free_percpu(p->percpu_cluster); - p->percpu_cluster = NULL; - free_percpu(p->cluster_next_cpu); - p->cluster_next_cpu = NULL; + kfree(p->global_cluster); + p->global_cluster = NULL; vfree(swap_map); + kvfree(zeromap); kvfree(cluster_info); /* Destroy swap account information */ swap_cgroup_swapoff(p->type); exit_swap_address_space(p->type); inode = mapping->host; - if (p->bdev_file) { - set_blocksize(p->bdev, old_block_size); - fput(p->bdev_file); - p->bdev_file = NULL; - } inode_lock(inode); inode->i_flags &= ~S_SWAPFILE; @@ -2658,7 +2907,7 @@ static int swap_show(struct seq_file *swap, void *v) } bytes = K(si->pages); - inuse = K(READ_ONCE(si->inuse_pages)); + inuse = K(swap_usage_in_pages(si)); file = si->swap_file; len = seq_file_path(swap, file, " \t\n\\"); @@ -2775,38 +3024,26 @@ static struct swap_info_struct *alloc_swap_info(void) } spin_lock_init(&p->lock); spin_lock_init(&p->cont_lock); + atomic_long_set(&p->inuse_pages, SWAP_USAGE_OFFLIST_BIT); init_completion(&p->comp); return p; } -static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) +static int claim_swapfile(struct swap_info_struct *si, struct inode *inode) { - int error; - if (S_ISBLK(inode->i_mode)) { - p->bdev_file = bdev_file_open_by_dev(inode->i_rdev, - BLK_OPEN_READ | BLK_OPEN_WRITE, p, NULL); - if (IS_ERR(p->bdev_file)) { - error = PTR_ERR(p->bdev_file); - p->bdev_file = NULL; - return error; - } - p->bdev = file_bdev(p->bdev_file); - p->old_block_size = block_size(p->bdev); - error = set_blocksize(p->bdev, PAGE_SIZE); - if (error < 0) - return error; + si->bdev = I_BDEV(inode); /* * Zoned block devices contain zones that have a sequential * write only restriction. Hence zoned block devices are not * suitable for swapping. Disallow them here. */ - if (bdev_is_zoned(p->bdev)) + if (bdev_is_zoned(si->bdev)) return -EINVAL; - p->flags |= SWP_BLKDEV; + si->flags |= SWP_BLKDEV; } else if (S_ISREG(inode->i_mode)) { - p->bdev = inode->i_sb->s_bdev; + si->bdev = inode->i_sb->s_bdev; } return 0; @@ -2841,7 +3078,7 @@ __weak unsigned long arch_max_swapfile_size(void) return generic_max_swapfile_size(); } -static unsigned long read_swap_header(struct swap_info_struct *p, +static unsigned long read_swap_header(struct swap_info_struct *si, union swap_header *swap_header, struct inode *inode) { @@ -2872,10 +3109,6 @@ static unsigned long read_swap_header(struct swap_info_struct *p, 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) { @@ -2892,7 +3125,6 @@ static unsigned long read_swap_header(struct swap_info_struct *p, if ((unsigned int)maxpages == 0) maxpages = UINT_MAX; } - p->highest_bit = maxpages - 1; if (!maxpages) return 0; @@ -2909,32 +3141,18 @@ static unsigned long read_swap_header(struct swap_info_struct *p, 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, +static int setup_swap_map_and_extents(struct swap_info_struct *si, 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; + unsigned long i; 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) @@ -2942,64 +3160,115 @@ static int setup_swap_map_and_extents(struct swap_info_struct *p, 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); + si->max = maxpages; + si->pages = nr_good_pages; + nr_extents = setup_swap_extents(si, span); if (nr_extents < 0) return nr_extents; - nr_good_pages = p->pages; + nr_good_pages = si->pages; } if (!nr_good_pages) { pr_warn("Empty swap-file\n"); return -EINVAL; } + return nr_extents; +} + +#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 struct swap_cluster_info *setup_clusters(struct swap_info_struct *si, + union swap_header *swap_header, + unsigned long maxpages) +{ + unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); + struct swap_cluster_info *cluster_info; + unsigned long i, j, idx; + int err = -ENOMEM; + + cluster_info = kvcalloc(nr_clusters, sizeof(*cluster_info), GFP_KERNEL); if (!cluster_info) - return nr_extents; + goto err; + + for (i = 0; i < nr_clusters; i++) + spin_lock_init(&cluster_info[i].lock); + + if (!(si->flags & SWP_SOLIDSTATE)) { + si->global_cluster = kmalloc(sizeof(*si->global_cluster), + GFP_KERNEL); + if (!si->global_cluster) + goto err_free; + for (i = 0; i < SWAP_NR_ORDERS; i++) + si->global_cluster->next[i] = SWAP_ENTRY_INVALID; + spin_lock_init(&si->global_cluster_lock); + } + /* + * Mark unusable pages as unavailable. The clusters aren't + * marked free yet, so no list operations are involved yet. + * + * See setup_swap_map_and_extents(): header page, bad pages, + * and the EOF part of the last cluster. + */ + inc_cluster_info_page(si, cluster_info, 0); + for (i = 0; i < swap_header->info.nr_badpages; i++) + inc_cluster_info_page(si, cluster_info, + swap_header->info.badpages[i]); + for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) + inc_cluster_info_page(si, cluster_info, i); + + INIT_LIST_HEAD(&si->free_clusters); + INIT_LIST_HEAD(&si->full_clusters); + INIT_LIST_HEAD(&si->discard_clusters); + + for (i = 0; i < SWAP_NR_ORDERS; i++) { + INIT_LIST_HEAD(&si->nonfull_clusters[i]); + INIT_LIST_HEAD(&si->frag_clusters[i]); + atomic_long_set(&si->frag_cluster_nr[i], 0); + } /* * 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 (j = 0; j < SWAP_CLUSTER_COLS; j++) { for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) { + struct swap_cluster_info *ci; idx = i * SWAP_CLUSTER_COLS + j; + ci = cluster_info + idx; if (idx >= nr_clusters) continue; - if (cluster_count(&cluster_info[idx])) + if (ci->count) { + ci->flags = CLUSTER_FLAG_NONFULL; + list_add_tail(&ci->list, &si->nonfull_clusters[0]); continue; - cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE); - cluster_list_add_tail(&p->free_clusters, cluster_info, - idx); + } + ci->flags = CLUSTER_FLAG_FREE; + list_add_tail(&ci->list, &si->free_clusters); } } - return nr_extents; + + return cluster_info; + +err_free: + kvfree(cluster_info); +err: + return ERR_PTR(err); } SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) { - struct swap_info_struct *p; + struct swap_info_struct *si; struct filename *name; struct file *swap_file = NULL; struct address_space *mapping; @@ -3011,8 +3280,9 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) sector_t span; unsigned long maxpages; unsigned char *swap_map = NULL; + unsigned long *zeromap = NULL; struct swap_cluster_info *cluster_info = NULL; - struct page *page = NULL; + struct folio *folio = NULL; struct inode *inode = NULL; bool inced_nr_rotate_swap = false; @@ -3025,11 +3295,12 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) if (!swap_avail_heads) return -ENOMEM; - p = alloc_swap_info(); - if (IS_ERR(p)) - return PTR_ERR(p); + si = alloc_swap_info(); + if (IS_ERR(si)) + return PTR_ERR(si); - INIT_WORK(&p->discard_work, swap_discard_work); + INIT_WORK(&si->discard_work, swap_discard_work); + INIT_WORK(&si->reclaim_work, swap_reclaim_work); name = getname(specialfile); if (IS_ERR(name)) { @@ -3037,19 +3308,19 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) name = NULL; goto bad_swap; } - swap_file = file_open_name(name, O_RDWR|O_LARGEFILE, 0); + swap_file = file_open_name(name, O_RDWR | O_LARGEFILE | O_EXCL, 0); if (IS_ERR(swap_file)) { error = PTR_ERR(swap_file); swap_file = NULL; goto bad_swap; } - p->swap_file = swap_file; + si->swap_file = swap_file; mapping = swap_file->f_mapping; dentry = swap_file->f_path.dentry; inode = mapping->host; - error = claim_swapfile(p, inode); + error = claim_swapfile(si, inode); if (unlikely(error)) goto bad_swap; @@ -3064,20 +3335,29 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) } /* + * The swap subsystem needs a major overhaul to support this. + * It doesn't work yet so just disable it for now. + */ + if (mapping_min_folio_order(mapping) > 0) { + error = -EINVAL; + 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); + folio = read_mapping_folio(mapping, 0, swap_file); + if (IS_ERR(folio)) { + error = PTR_ERR(folio); goto bad_swap_unlock_inode; } - swap_header = kmap(page); + swap_header = kmap_local_folio(folio, 0); - maxpages = read_swap_header(p, swap_header, inode); + maxpages = read_swap_header(si, swap_header, inode); if (unlikely(!maxpages)) { error = -EINVAL; goto bad_swap_unlock_inode; @@ -3090,77 +3370,57 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) goto bad_swap_unlock_inode; } - if (p->bdev && bdev_stable_writes(p->bdev)) - p->flags |= SWP_STABLE_WRITES; - - if (p->bdev && bdev_synchronous(p->bdev)) - p->flags |= SWP_SYNCHRONOUS_IO; + error = swap_cgroup_swapon(si->type, maxpages); + if (error) + goto bad_swap_unlock_inode; - if (p->bdev && bdev_nonrot(p->bdev)) { - int cpu; - unsigned long ci, nr_cluster; + nr_extents = setup_swap_map_and_extents(si, swap_header, swap_map, + maxpages, &span); + if (unlikely(nr_extents < 0)) { + error = nr_extents; + goto bad_swap_unlock_inode; + } - 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) = - get_random_u32_inclusive(1, p->highest_bit); - } - nr_cluster = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); + /* + * Use kvmalloc_array instead of bitmap_zalloc as the allocation order might + * be above MAX_PAGE_ORDER incase of a large swap file. + */ + zeromap = kvmalloc_array(BITS_TO_LONGS(maxpages), sizeof(long), + GFP_KERNEL | __GFP_ZERO); + if (!zeromap) { + error = -ENOMEM; + goto bad_swap_unlock_inode; + } - cluster_info = kvcalloc(nr_cluster, sizeof(*cluster_info), - GFP_KERNEL); - if (!cluster_info) { - error = -ENOMEM; - goto bad_swap_unlock_inode; - } + if (si->bdev && bdev_stable_writes(si->bdev)) + si->flags |= SWP_STABLE_WRITES; - for (ci = 0; ci < nr_cluster; ci++) - spin_lock_init(&((cluster_info + ci)->lock)); + if (si->bdev && bdev_synchronous(si->bdev)) + si->flags |= SWP_SYNCHRONOUS_IO; - 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); - } + if (si->bdev && bdev_nonrot(si->bdev)) { + si->flags |= SWP_SOLIDSTATE; } 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; + cluster_info = setup_clusters(si, swap_header, maxpages); + if (IS_ERR(cluster_info)) { + error = PTR_ERR(cluster_info); + cluster_info = NULL; goto bad_swap_unlock_inode; } if ((swap_flags & SWAP_FLAG_DISCARD) && - p->bdev && bdev_max_discard_sectors(p->bdev)) { + si->bdev && bdev_max_discard_sectors(si->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 | + si->flags |= (SWP_DISCARDABLE | SWP_AREA_DISCARD | SWP_PAGE_DISCARD); /* @@ -3170,24 +3430,24 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) * Now it's time to adjust the p->flags accordingly. */ if (swap_flags & SWAP_FLAG_DISCARD_ONCE) - p->flags &= ~SWP_PAGE_DISCARD; + si->flags &= ~SWP_PAGE_DISCARD; else if (swap_flags & SWAP_FLAG_DISCARD_PAGES) - p->flags &= ~SWP_AREA_DISCARD; + si->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 (si->flags & SWP_AREA_DISCARD) { + int err = discard_swap(si); if (unlikely(err)) pr_err("swapon: discard_swap(%p): %d\n", - p, err); + si, err); } } - error = init_swap_address_space(p->type, maxpages); + error = init_swap_address_space(si->type, maxpages); if (error) goto bad_swap_unlock_inode; - error = zswap_swapon(p->type, maxpages); + error = zswap_swapon(si->type, maxpages); if (error) goto free_swap_address_space; @@ -3205,17 +3465,16 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) 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); + prio = swap_flags & SWAP_FLAG_PRIO_MASK; + enable_swap_info(si, prio, swap_map, cluster_info, zeromap); pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s\n", - K(p->pages), name->name, p->prio, nr_extents, + K(si->pages), name->name, si->prio, nr_extents, K((unsigned long long)span), - (p->flags & SWP_SOLIDSTATE) ? "SS" : "", - (p->flags & SWP_DISCARDABLE) ? "D" : "", - (p->flags & SWP_AREA_DISCARD) ? "s" : "", - (p->flags & SWP_PAGE_DISCARD) ? "c" : ""); + (si->flags & SWP_SOLIDSTATE) ? "SS" : "", + (si->flags & SWP_DISCARDABLE) ? "D" : "", + (si->flags & SWP_AREA_DISCARD) ? "s" : "", + (si->flags & SWP_PAGE_DISCARD) ? "c" : ""); mutex_unlock(&swapon_mutex); atomic_inc(&proc_poll_event); @@ -3224,45 +3483,35 @@ SYSCALL_DEFINE2(swapon, const char __user *, specialfile, int, swap_flags) error = 0; goto out; free_swap_zswap: - zswap_swapoff(p->type); + zswap_swapoff(si->type); free_swap_address_space: - exit_swap_address_space(p->type); + exit_swap_address_space(si->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 (p->bdev_file) { - set_blocksize(p->bdev, p->old_block_size); - fput(p->bdev_file); - p->bdev_file = NULL; - } + kfree(si->global_cluster); + si->global_cluster = NULL; inode = NULL; - destroy_swap_extents(p); - swap_cgroup_swapoff(p->type); + destroy_swap_extents(si); + swap_cgroup_swapoff(si->type); spin_lock(&swap_lock); - p->swap_file = NULL; - p->flags = 0; + si->swap_file = NULL; + si->flags = 0; spin_unlock(&swap_lock); vfree(swap_map); + kvfree(zeromap); kvfree(cluster_info); 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 (!IS_ERR_OR_NULL(folio)) + folio_release_kmap(folio, swap_header); if (name) putname(name); if (inode) inode_unlock(inode); - if (!error) - enable_swap_slots_cache(); return error; } @@ -3276,7 +3525,7 @@ void si_swapinfo(struct sysinfo *val) 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); + nr_to_be_unused += swap_usage_in_pages(si); } val->freeswap = atomic_long_read(&nr_swap_pages) + nr_to_be_unused; val->totalswap = total_swap_pages + nr_to_be_unused; @@ -3284,73 +3533,89 @@ void si_swapinfo(struct sysinfo *val) } /* - * Verify that a swap entry is valid and increment its swap map count. + * Verify that nr swap entries are valid and increment their swap map counts. * * 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) +static int __swap_duplicate(swp_entry_t entry, unsigned char usage, int nr) { - struct swap_info_struct *p; + struct swap_info_struct *si; struct swap_cluster_info *ci; unsigned long offset; unsigned char count; unsigned char has_cache; - int err; + int err, i; - p = swp_swap_info(entry); + si = swp_swap_info(entry); + if (WARN_ON_ONCE(!si)) { + pr_err("%s%08lx\n", Bad_file, entry.val); + 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; - } + VM_WARN_ON(nr > SWAPFILE_CLUSTER - offset % SWAPFILE_CLUSTER); + VM_WARN_ON(usage == 1 && nr > 1); + ci = lock_cluster(si, offset); - has_cache = count & SWAP_HAS_CACHE; - count &= ~SWAP_HAS_CACHE; err = 0; + for (i = 0; i < nr; i++) { + count = si->swap_map[offset + i]; - if (usage == SWAP_HAS_CACHE) { + /* + * 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; + } - /* 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 */ + has_cache = count & SWAP_HAS_CACHE; + count &= ~SWAP_HAS_CACHE; + + if (!count && !has_cache) { err = -ENOENT; + } else if (usage == SWAP_HAS_CACHE) { + if (has_cache) + err = -EEXIST; + } else if ((count & ~COUNT_CONTINUED) > SWAP_MAP_MAX) { + err = -EINVAL; + } - } else if (count || has_cache) { + if (err) + goto unlock_out; + } + + for (i = 0; i < nr; i++) { + count = si->swap_map[offset + i]; + has_cache = count & SWAP_HAS_CACHE; + count &= ~SWAP_HAS_CACHE; - if ((count & ~COUNT_CONTINUED) < SWAP_MAP_MAX) + if (usage == SWAP_HAS_CACHE) + has_cache = SWAP_HAS_CACHE; + else 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)) + else if (swap_count_continued(si, offset + i, count)) count = COUNT_CONTINUED; - else + else { + /* + * Don't need to rollback changes, because if + * usage == 1, there must be nr == 1. + */ err = -ENOMEM; - } else - err = -ENOENT; /* unused swap entry */ + goto unlock_out; + } - if (!err) - WRITE_ONCE(p->swap_map[offset], count | has_cache); + WRITE_ONCE(si->swap_map[offset + i], count | has_cache); + } unlock_out: - unlock_cluster_or_swap_info(p, ci); + unlock_cluster(ci); return err; } @@ -3358,9 +3623,9 @@ unlock_out: * 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) +void swap_shmem_alloc(swp_entry_t entry, int nr) { - __swap_duplicate(entry, SWAP_MAP_SHMEM); + __swap_duplicate(entry, SWAP_MAP_SHMEM, nr); } /* @@ -3374,57 +3639,37 @@ int swap_duplicate(swp_entry_t entry) { int err = 0; - while (!err && __swap_duplicate(entry, 1) == -ENOMEM) + while (!err && __swap_duplicate(entry, 1, 1) == -ENOMEM) err = add_swap_count_continuation(entry, GFP_ATOMIC); return err; } /* - * @entry: swap entry for which we allocate swap cache. + * @entry: first swap entry from which we allocate nr swap cache. * - * Called when allocating swap cache for existing swap entry, + * Called when allocating swap cache for existing swap entries, * 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); -} - -void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry) -{ - struct swap_cluster_info *ci; - unsigned long offset = swp_offset(entry); - unsigned char usage; - - ci = lock_cluster_or_swap_info(si, offset); - usage = __swap_entry_free_locked(si, offset, SWAP_HAS_CACHE); - unlock_cluster_or_swap_info(si, ci); - if (!usage) - free_swap_slot(entry); -} - -struct swap_info_struct *swp_swap_info(swp_entry_t entry) +int swapcache_prepare(swp_entry_t entry, int nr) { - return swap_type_to_swap_info(swp_type(entry)); + return __swap_duplicate(entry, SWAP_HAS_CACHE, nr); } /* - * out-of-line methods to avoid include hell. + * Caller should ensure entries belong to the same folio so + * the entries won't span cross cluster boundary. */ -struct address_space *swapcache_mapping(struct folio *folio) +void swapcache_clear(struct swap_info_struct *si, swp_entry_t entry, int nr) { - return swp_swap_info(folio->swap)->swap_file->f_mapping; + swap_entries_put_cache(si, entry, nr); } -EXPORT_SYMBOL_GPL(swapcache_mapping); -pgoff_t __page_file_index(struct page *page) +struct swap_info_struct *swp_swap_info(swp_entry_t entry) { - swp_entry_t swap = page_swap_entry(page); - return swp_offset(swap); + return swap_type_to_swap_info(swp_type(entry)); } -EXPORT_SYMBOL_GPL(__page_file_index); /* * add_swap_count_continuation - called when a swap count is duplicated @@ -3466,7 +3711,6 @@ int add_swap_count_continuation(swp_entry_t entry, gfp_t gfp_mask) */ goto outer; } - spin_lock(&si->lock); offset = swp_offset(entry); @@ -3531,7 +3775,6 @@ out_unlock_cont: spin_unlock(&si->cont_lock); out: unlock_cluster(ci); - spin_unlock(&si->lock); put_swap_device(si); outer: if (page) @@ -3545,8 +3788,8 @@ outer: * 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. + * Called while __swap_duplicate() or caller of swap_entry_put_locked() + * holds cluster lock. */ static bool swap_count_continued(struct swap_info_struct *si, pgoff_t offset, unsigned char count) @@ -3651,6 +3894,11 @@ static void free_swap_count_continuations(struct swap_info_struct *si) } #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP) +static bool __has_usable_swap(void) +{ + return !plist_head_empty(&swap_active_head); +} + void __folio_throttle_swaprate(struct folio *folio, gfp_t gfp) { struct swap_info_struct *si, *next; @@ -3659,6 +3907,9 @@ void __folio_throttle_swaprate(struct folio *folio, gfp_t gfp) if (!(gfp & __GFP_IO)) return; + if (!__has_usable_swap()) + return; + if (!blk_cgroup_congested()) return; |