| // SPDX-License-Identifier: GPL-2.0-only |
| /* |
| * linux/mm/swapfile.c |
| * |
| * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds |
| * Swap reorganised 29.12.95, Stephen Tweedie |
| */ |
| |
| #include <linux/mm.h> |
| #include <linux/sched/mm.h> |
| #include <linux/sched/task.h> |
| #include <linux/hugetlb.h> |
| #include <linux/mman.h> |
| #include <linux/slab.h> |
| #include <linux/kernel_stat.h> |
| #include <linux/swap.h> |
| #include <linux/vmalloc.h> |
| #include <linux/pagemap.h> |
| #include <linux/namei.h> |
| #include <linux/shmem_fs.h> |
| #include <linux/blkdev.h> |
| #include <linux/random.h> |
| #include <linux/writeback.h> |
| #include <linux/proc_fs.h> |
| #include <linux/seq_file.h> |
| #include <linux/init.h> |
| #include <linux/ksm.h> |
| #include <linux/rmap.h> |
| #include <linux/security.h> |
| #include <linux/backing-dev.h> |
| #include <linux/mutex.h> |
| #include <linux/capability.h> |
| #include <linux/syscalls.h> |
| #include <linux/memcontrol.h> |
| #include <linux/poll.h> |
| #include <linux/oom.h> |
| #include <linux/frontswap.h> |
| #include <linux/swapfile.h> |
| #include <linux/export.h> |
| #include <linux/swap_slots.h> |
| #include <linux/sort.h> |
| |
| #include <asm/pgtable.h> |
| #include <asm/tlbflush.h> |
| #include <linux/swapops.h> |
| #include <linux/swap_cgroup.h> |
| |
| static bool swap_count_continued(struct swap_info_struct *, pgoff_t, |
| unsigned char); |
| static void free_swap_count_continuations(struct swap_info_struct *); |
| static sector_t map_swap_entry(swp_entry_t, struct block_device**); |
| |
| DEFINE_SPINLOCK(swap_lock); |
| static unsigned int nr_swapfiles; |
| atomic_long_t nr_swap_pages; |
| /* |
| * Some modules use swappable objects and may try to swap them out under |
| * memory pressure (via the shrinker). Before doing so, they may wish to |
| * check to see if any swap space is available. |
| */ |
| EXPORT_SYMBOL_GPL(nr_swap_pages); |
| /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */ |
| long total_swap_pages; |
| static int least_priority = -1; |
| |
| static const char Bad_file[] = "Bad swap file entry "; |
| static const char Unused_file[] = "Unused swap file entry "; |
| static const char Bad_offset[] = "Bad swap offset entry "; |
| static const char Unused_offset[] = "Unused swap offset entry "; |
| |
| /* |
| * all active swap_info_structs |
| * protected with swap_lock, and ordered by priority. |
| */ |
| PLIST_HEAD(swap_active_head); |
| |
| /* |
| * all available (active, not full) swap_info_structs |
| * protected with swap_avail_lock, ordered by priority. |
| * This is used by get_swap_page() instead of swap_active_head |
| * because swap_active_head includes all swap_info_structs, |
| * but get_swap_page() doesn't need to look at full ones. |
| * This uses its own lock instead of swap_lock because when a |
| * swap_info_struct changes between not-full/full, it needs to |
| * add/remove itself to/from this list, but the swap_info_struct->lock |
| * is held and the locking order requires swap_lock to be taken |
| * before any swap_info_struct->lock. |
| */ |
| static struct plist_head *swap_avail_heads; |
| static DEFINE_SPINLOCK(swap_avail_lock); |
| |
| struct swap_info_struct *swap_info[MAX_SWAPFILES]; |
| |
| static DEFINE_MUTEX(swapon_mutex); |
| |
| static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait); |
| /* Activity counter to indicate that a swapon or swapoff has occurred */ |
| static atomic_t proc_poll_event = ATOMIC_INIT(0); |
| |
| atomic_t nr_rotate_swap = ATOMIC_INIT(0); |
| |
| static struct swap_info_struct *swap_type_to_swap_info(int type) |
| { |
| if (type >= READ_ONCE(nr_swapfiles)) |
| return NULL; |
| |
| smp_rmb(); /* Pairs with smp_wmb in alloc_swap_info. */ |
| return READ_ONCE(swap_info[type]); |
| } |
| |
| static inline unsigned char swap_count(unsigned char ent) |
| { |
| return ent & ~SWAP_HAS_CACHE; /* may include COUNT_CONTINUED flag */ |
| } |
| |
| /* Reclaim the swap entry anyway if possible */ |
| #define TTRS_ANYWAY 0x1 |
| /* |
| * Reclaim the swap entry if there are no more mappings of the |
| * corresponding page |
| */ |
| #define TTRS_UNMAPPED 0x2 |
| /* Reclaim the swap entry if swap is getting full*/ |
| #define TTRS_FULL 0x4 |
| |
| /* returns 1 if swap entry is freed */ |
| static int __try_to_reclaim_swap(struct swap_info_struct *si, |
| unsigned long offset, unsigned long flags) |
| { |
| swp_entry_t entry = swp_entry(si->type, offset); |
| struct page *page; |
| int ret = 0; |
| |
| page = find_get_page(swap_address_space(entry), offset); |
| if (!page) |
| return 0; |
| /* |
| * When this function is called from scan_swap_map_slots() and it's |
| * called by vmscan.c at reclaiming pages. So, we hold a lock on a page, |
| * here. We have to use trylock for avoiding deadlock. This is a special |
| * case and you should use try_to_free_swap() with explicit lock_page() |
| * in usual operations. |
| */ |
| if (trylock_page(page)) { |
| if ((flags & TTRS_ANYWAY) || |
| ((flags & TTRS_UNMAPPED) && !page_mapped(page)) || |
| ((flags & TTRS_FULL) && mem_cgroup_swap_full(page))) |
| ret = try_to_free_swap(page); |
| unlock_page(page); |
| } |
| put_page(page); |
| return ret; |
| } |
| |
| static inline struct swap_extent *first_se(struct swap_info_struct *sis) |
| { |
| struct rb_node *rb = rb_first(&sis->swap_extent_root); |
| return rb_entry(rb, struct swap_extent, rb_node); |
| } |
| |
| static inline struct swap_extent *next_se(struct swap_extent *se) |
| { |
| struct rb_node *rb = rb_next(&se->rb_node); |
| return rb ? rb_entry(rb, struct swap_extent, rb_node) : NULL; |
| } |
| |
| /* |
| * swapon tell device that all the old swap contents can be discarded, |
| * to allow the swap device to optimize its wear-levelling. |
| */ |
| static int discard_swap(struct swap_info_struct *si) |
| { |
| struct swap_extent *se; |
| sector_t start_block; |
| sector_t nr_blocks; |
| int err = 0; |
| |
| /* Do not discard the swap header page! */ |
| se = first_se(si); |
| start_block = (se->start_block + 1) << (PAGE_SHIFT - 9); |
| nr_blocks = ((sector_t)se->nr_pages - 1) << (PAGE_SHIFT - 9); |
| if (nr_blocks) { |
| err = blkdev_issue_discard(si->bdev, start_block, |
| nr_blocks, GFP_KERNEL, 0); |
| if (err) |
| return err; |
| cond_resched(); |
| } |
| |
| for (se = next_se(se); se; se = next_se(se)) { |
| start_block = se->start_block << (PAGE_SHIFT - 9); |
| nr_blocks = (sector_t)se->nr_pages << (PAGE_SHIFT - 9); |
| |
| err = blkdev_issue_discard(si->bdev, start_block, |
| nr_blocks, GFP_KERNEL, 0); |
| if (err) |
| break; |
| |
| cond_resched(); |
| } |
| return err; /* That will often be -EOPNOTSUPP */ |
| } |
| |
| static struct swap_extent * |
| offset_to_swap_extent(struct swap_info_struct *sis, unsigned long offset) |
| { |
| struct swap_extent *se; |
| struct rb_node *rb; |
| |
| rb = sis->swap_extent_root.rb_node; |
| while (rb) { |
| se = rb_entry(rb, struct swap_extent, rb_node); |
| if (offset < se->start_page) |
| rb = rb->rb_left; |
| else if (offset >= se->start_page + se->nr_pages) |
| rb = rb->rb_right; |
| else |
| return se; |
| } |
| /* It *must* be present */ |
| BUG(); |
| } |
| |
| /* |
| * swap allocation tell device that a cluster of swap can now be discarded, |
| * to allow the swap device to optimize its wear-levelling. |
| */ |
| static void discard_swap_cluster(struct swap_info_struct *si, |
| pgoff_t start_page, pgoff_t nr_pages) |
| { |
| struct swap_extent *se = offset_to_swap_extent(si, start_page); |
| |
| while (nr_pages) { |
| pgoff_t offset = start_page - se->start_page; |
| sector_t start_block = se->start_block + offset; |
| sector_t nr_blocks = se->nr_pages - offset; |
| |
| if (nr_blocks > nr_pages) |
| nr_blocks = nr_pages; |
| start_page += nr_blocks; |
| nr_pages -= nr_blocks; |
| |
| start_block <<= PAGE_SHIFT - 9; |
| nr_blocks <<= PAGE_SHIFT - 9; |
| if (blkdev_issue_discard(si->bdev, start_block, |
| nr_blocks, GFP_NOIO, 0)) |
| break; |
| |
| se = next_se(se); |
| } |
| } |
| |
| #ifdef CONFIG_THP_SWAP |
| #define SWAPFILE_CLUSTER HPAGE_PMD_NR |
| |
| #define swap_entry_size(size) (size) |
| #else |
| #define SWAPFILE_CLUSTER 256 |
| |
| /* |
| * Define swap_entry_size() as constant to let compiler to optimize |
| * out some code if !CONFIG_THP_SWAP |
| */ |
| #define swap_entry_size(size) 1 |
| #endif |
| #define LATENCY_LIMIT 256 |
| |
| static inline void cluster_set_flag(struct swap_cluster_info *info, |
| unsigned int flag) |
| { |
| info->flags = flag; |
| } |
| |
| static inline unsigned int cluster_count(struct swap_cluster_info *info) |
| { |
| return info->data; |
| } |
| |
| static inline void cluster_set_count(struct swap_cluster_info *info, |
| unsigned int c) |
| { |
| info->data = c; |
| } |
| |
| static inline void cluster_set_count_flag(struct swap_cluster_info *info, |
| unsigned int c, unsigned int f) |
| { |
| info->flags = f; |
| info->data = c; |
| } |
| |
| static inline unsigned int cluster_next(struct swap_cluster_info *info) |
| { |
| return info->data; |
| } |
| |
| static inline void cluster_set_next(struct swap_cluster_info *info, |
| unsigned int n) |
| { |
| info->data = n; |
| } |
| |
| static inline void cluster_set_next_flag(struct swap_cluster_info *info, |
| unsigned int n, unsigned int f) |
| { |
| info->flags = f; |
| info->data = n; |
| } |
| |
| static inline bool cluster_is_free(struct swap_cluster_info *info) |
| { |
| return info->flags & CLUSTER_FLAG_FREE; |
| } |
| |
| static inline bool cluster_is_null(struct swap_cluster_info *info) |
| { |
| return info->flags & CLUSTER_FLAG_NEXT_NULL; |
| } |
| |
| static inline void cluster_set_null(struct swap_cluster_info *info) |
| { |
| info->flags = CLUSTER_FLAG_NEXT_NULL; |
| info->data = 0; |
| } |
| |
| static inline bool cluster_is_huge(struct swap_cluster_info *info) |
| { |
| if (IS_ENABLED(CONFIG_THP_SWAP)) |
| return info->flags & CLUSTER_FLAG_HUGE; |
| return false; |
| } |
| |
| static inline void cluster_clear_huge(struct swap_cluster_info *info) |
| { |
| info->flags &= ~CLUSTER_FLAG_HUGE; |
| } |
| |
| static inline struct swap_cluster_info *lock_cluster(struct swap_info_struct *si, |
| unsigned long offset) |
| { |
| struct swap_cluster_info *ci; |
| |
| ci = si->cluster_info; |
| if (ci) { |
| ci += offset / SWAPFILE_CLUSTER; |
| spin_lock(&ci->lock); |
| } |
| return ci; |
| } |
| |
| static inline void unlock_cluster(struct swap_cluster_info *ci) |
| { |
| if (ci) |
| spin_unlock(&ci->lock); |
| } |
| |
| /* |
| * Determine the locking method in use for this device. Return |
| * swap_cluster_info if SSD-style cluster-based locking is in place. |
| */ |
| static inline struct swap_cluster_info *lock_cluster_or_swap_info( |
| struct swap_info_struct *si, unsigned long offset) |
| { |
| struct swap_cluster_info *ci; |
| |
| /* Try to use fine-grained SSD-style locking if available: */ |
| ci = lock_cluster(si, offset); |
| /* Otherwise, fall back to traditional, coarse locking: */ |
| if (!ci) |
| spin_lock(&si->lock); |
| |
| return ci; |
| } |
| |
| static inline void unlock_cluster_or_swap_info(struct swap_info_struct *si, |
| struct swap_cluster_info *ci) |
| { |
| if (ci) |
| unlock_cluster(ci); |
| else |
| spin_unlock(&si->lock); |
| } |
| |
| static inline bool cluster_list_empty(struct swap_cluster_list *list) |
| { |
| return cluster_is_null(&list->head); |
| } |
| |
| static inline unsigned int cluster_list_first(struct swap_cluster_list *list) |
| { |
| return cluster_next(&list->head); |
| } |
| |
| static void cluster_list_init(struct swap_cluster_list *list) |
| { |
| cluster_set_null(&list->head); |
| cluster_set_null(&list->tail); |
| } |
| |
| static void cluster_list_add_tail(struct swap_cluster_list *list, |
| struct swap_cluster_info *ci, |
| unsigned int idx) |
| { |
| if (cluster_list_empty(list)) { |
| cluster_set_next_flag(&list->head, idx, 0); |
| cluster_set_next_flag(&list->tail, idx, 0); |
| } else { |
| struct swap_cluster_info *ci_tail; |
| unsigned int tail = cluster_next(&list->tail); |
| |
| /* |
| * Nested cluster lock, but both cluster locks are |
| * only acquired when we held swap_info_struct->lock |
| */ |
| ci_tail = ci + tail; |
| spin_lock_nested(&ci_tail->lock, SINGLE_DEPTH_NESTING); |
| cluster_set_next(ci_tail, idx); |
| spin_unlock(&ci_tail->lock); |
| cluster_set_next_flag(&list->tail, idx, 0); |
| } |
| } |
| |
| static unsigned int cluster_list_del_first(struct swap_cluster_list *list, |
| struct swap_cluster_info *ci) |
| { |
| unsigned int idx; |
| |
| idx = cluster_next(&list->head); |
| if (cluster_next(&list->tail) == idx) { |
| cluster_set_null(&list->head); |
| cluster_set_null(&list->tail); |
| } else |
| cluster_set_next_flag(&list->head, |
| cluster_next(&ci[idx]), 0); |
| |
| return idx; |
| } |
| |
| /* Add a cluster to discard list and schedule it to do discard */ |
| static void swap_cluster_schedule_discard(struct swap_info_struct *si, |
| unsigned int idx) |
| { |
| /* |
| * If scan_swap_map() 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(), mark the swap entries bad (occupied). It |
| * will be cleared after discard |
| */ |
| memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
| SWAP_MAP_BAD, SWAPFILE_CLUSTER); |
| |
| cluster_list_add_tail(&si->discard_clusters, si->cluster_info, idx); |
| |
| schedule_work(&si->discard_work); |
| } |
| |
| static void __free_cluster(struct swap_info_struct *si, unsigned long idx) |
| { |
| struct swap_cluster_info *ci = si->cluster_info; |
| |
| cluster_set_flag(ci + idx, CLUSTER_FLAG_FREE); |
| cluster_list_add_tail(&si->free_clusters, ci, idx); |
| } |
| |
| /* |
| * Doing discard actually. After a cluster discard is finished, the cluster |
| * will be added to free cluster list. caller should hold si->lock. |
| */ |
| static void swap_do_scheduled_discard(struct swap_info_struct *si) |
| { |
| struct swap_cluster_info *info, *ci; |
| unsigned int idx; |
| |
| info = si->cluster_info; |
| |
| while (!cluster_list_empty(&si->discard_clusters)) { |
| idx = cluster_list_del_first(&si->discard_clusters, info); |
| spin_unlock(&si->lock); |
| |
| discard_swap_cluster(si, idx * SWAPFILE_CLUSTER, |
| SWAPFILE_CLUSTER); |
| |
| spin_lock(&si->lock); |
| ci = lock_cluster(si, idx * SWAPFILE_CLUSTER); |
| __free_cluster(si, idx); |
| memset(si->swap_map + idx * SWAPFILE_CLUSTER, |
| 0, SWAPFILE_CLUSTER); |
| unlock_cluster(ci); |
| } |
| } |
| |
| static void swap_discard_work(struct work_struct *work) |
| { |
| struct swap_info_struct *si; |
| |
| si = container_of(work, struct swap_info_struct, discard_work); |
| |
| spin_lock(&si->lock); |
| swap_do_scheduled_discard(si); |
| spin_unlock(&si->lock); |
| } |
| |
| static void alloc_cluster(struct swap_info_struct *si, unsigned long idx) |
| { |
| struct swap_cluster_info *ci = si->cluster_info; |
| |
| VM_BUG_ON(cluster_list_first(&si->free_clusters) != idx); |
| cluster_list_del_first(&si->free_clusters, ci); |
| cluster_set_count_flag(ci + idx, 0, 0); |
| } |
| |
| static void free_cluster(struct swap_info_struct *si, unsigned long idx) |
| { |
| struct swap_cluster_info *ci = si->cluster_info + idx; |
| |
| VM_BUG_ON(cluster_count(ci) != 0); |
| /* |
| * If the swap is discardable, prepare discard the cluster |
| * instead of free it immediately. The cluster will be freed |
| * after discard. |
| */ |
| if ((si->flags & (SWP_WRITEOK | SWP_PAGE_DISCARD)) == |
| (SWP_WRITEOK | SWP_PAGE_DISCARD)) { |
| swap_cluster_schedule_discard(si, idx); |
| return; |
| } |
| |
| __free_cluster(si, idx); |
| } |
| |
| /* |
| * The cluster corresponding to page_nr will be used. The cluster will be |
| * removed from free cluster list and its usage counter will be increased. |
| */ |
| static void inc_cluster_info_page(struct swap_info_struct *p, |
| struct swap_cluster_info *cluster_info, unsigned long page_nr) |
| { |
| unsigned long idx = page_nr / SWAPFILE_CLUSTER; |
| |
| if (!cluster_info) |
| return; |
| if (cluster_is_free(&cluster_info[idx])) |
| alloc_cluster(p, idx); |
| |
| VM_BUG_ON(cluster_count(&cluster_info[idx]) >= SWAPFILE_CLUSTER); |
| cluster_set_count(&cluster_info[idx], |
| cluster_count(&cluster_info[idx]) + 1); |
| } |
| |
| /* |
| * The cluster corresponding to page_nr decreases one usage. If the usage |
| * counter becomes 0, which means no page in the cluster is in using, we can |
| * optionally discard the cluster and add it to free cluster list. |
| */ |
| static void dec_cluster_info_page(struct swap_info_struct *p, |
| struct swap_cluster_info *cluster_info, unsigned long page_nr) |
| { |
| unsigned long idx = page_nr / SWAPFILE_CLUSTER; |
| |
| if (!cluster_info) |
| return; |
| |
| VM_BUG_ON(cluster_count(&cluster_info[idx]) == 0); |
| cluster_set_count(&cluster_info[idx], |
| cluster_count(&cluster_info[idx]) - 1); |
| |
| if (cluster_count(&cluster_info[idx]) == 0) |
| free_cluster(p, idx); |
| } |
| |
| /* |
| * It's possible scan_swap_map() uses a free cluster in the middle of free |
| * cluster list. Avoiding such abuse to avoid list corruption. |
| */ |
| static bool |
| scan_swap_map_ssd_cluster_conflict(struct swap_info_struct *si, |
| unsigned long offset) |
| { |
| struct percpu_cluster *percpu_cluster; |
| bool conflict; |
| |
| offset /= SWAPFILE_CLUSTER; |
| conflict = !cluster_list_empty(&si->free_clusters) && |
| offset != cluster_list_first(&si->free_clusters) && |
| cluster_is_free(&si->cluster_info[offset]); |
| |
| if (!conflict) |
| return false; |
| |
| percpu_cluster = this_cpu_ptr(si->percpu_cluster); |
| cluster_set_null(&percpu_cluster->index); |
| return true; |
| } |
| |
| /* |
| * Try to get a swap entry from current cpu's swap entry pool (a cluster). This |
| * might involve allocating a new cluster for current CPU too. |
| */ |
| static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct *si, |
| unsigned long *offset, unsigned long *scan_base) |
| { |
| struct percpu_cluster *cluster; |
| struct swap_cluster_info *ci; |
| unsigned long tmp, max; |
| |
| new_cluster: |
| cluster = this_cpu_ptr(si->percpu_cluster); |
| if (cluster_is_null(&cluster->index)) { |
| if (!cluster_list_empty(&si->free_clusters)) { |
| cluster->index = si->free_clusters.head; |
| cluster->next = cluster_next(&cluster->index) * |
| SWAPFILE_CLUSTER; |
| } else if (!cluster_list_empty(&si->discard_clusters)) { |
| /* |
| * we don't have free cluster but have some clusters in |
| * discarding, do discard now and reclaim them, then |
| * reread cluster_next_cpu since we dropped si->lock |
| */ |
| swap_do_scheduled_discard(si); |
| *scan_base = this_cpu_read(*si->cluster_next_cpu); |
| *offset = *scan_base; |
| goto new_cluster; |
| } else |
| return false; |
| } |
| |
| /* |
| * Other CPUs can use our cluster if they can't find a free cluster, |
| * check if there is still free entry in the cluster |
| */ |
| tmp = cluster->next; |
| max = min_t(unsigned long, si->max, |
| (cluster_next(&cluster->index) + 1) * SWAPFILE_CLUSTER); |
| if (tmp < max) { |
| ci = lock_cluster(si, tmp); |
| while (tmp < max) { |
| if (!si->swap_map[tmp]) |
| break; |
| tmp++; |
| } |
| unlock_cluster(ci); |
| } |
| if (tmp >= max) { |
| cluster_set_null(&cluster->index); |
| goto new_cluster; |
| } |
| cluster->next = tmp + 1; |
| *offset = tmp; |
| *scan_base = tmp; |
| return true; |
| } |
| |
| static void __del_from_avail_list(struct swap_info_struct *p) |
| { |
| int nid; |
| |
| for_each_node(nid) |
| plist_del(&p->avail_lists[nid], &swap_avail_heads[nid]); |
| } |
| |
| static void del_from_avail_list(struct swap_info_struct *p) |
| { |
| spin_lock(&swap_avail_lock); |
| __del_from_avail_list(p); |
| spin_unlock(&swap_avail_lock); |
| } |
| |
| static void swap_range_alloc(struct swap_info_struct *si, unsigned long offset, |
| unsigned int nr_entries) |
| { |
| unsigned int end = offset + nr_entries - 1; |
| |
| if (offset == si->lowest_bit) |
| si->lowest_bit += nr_entries; |
| if (end == si->highest_bit) |
| si->highest_bit -= nr_entries; |
| si->inuse_pages += nr_entries; |
| if (si->inuse_pages == si->pages) { |
| si->lowest_bit = si->max; |
| si->highest_bit = 0; |
| del_from_avail_list(si); |
| } |
| } |
| |
| static void add_to_avail_list(struct swap_info_struct *p) |
| { |
| int nid; |
| |
| spin_lock(&swap_avail_lock); |
| for_each_node(nid) { |
| WARN_ON(!plist_node_empty(&p->avail_lists[nid])); |
| plist_add(&p->avail_lists[nid], &swap_avail_heads[nid]); |
| } |
| spin_unlock(&swap_avail_lock); |
| } |
| |
| static void swap_range_free(struct swap_info_struct *si, unsigned long offset, |
| unsigned int nr_entries) |
| { |
| unsigned long end = offset + nr_entries - 1; |
| void (*swap_slot_free_notify)(struct block_device *, unsigned long); |
| |
| if (offset < si->lowest_bit) |
| si->lowest_bit = offset; |
| if (end > si->highest_bit) { |
| bool was_full = !si->highest_bit; |
| |
| si->highest_bit = end; |
| if (was_full && (si->flags & SWP_WRITEOK)) |
| add_to_avail_list(si); |
| } |
| atomic_long_add(nr_entries, &nr_swap_pages); |
| si->inuse_pages -= nr_entries; |
| if (si->flags & SWP_BLKDEV) |
| swap_slot_free_notify = |
| si->bdev->bd_disk->fops->swap_slot_free_notify; |
| else |
| swap_slot_free_notify = NULL; |
| while (offset <= end) { |
| frontswap_invalidate_page(si->type, offset); |
| if (swap_slot_free_notify) |
| swap_slot_free_notify(si->bdev, offset); |
| offset++; |
| } |
| } |
| |
| static void set_cluster_next(struct swap_info_struct *si, unsigned long next) |
| { |
| unsigned long prev; |
| |
| if (!(si->flags & SWP_SOLIDSTATE)) { |
| si->cluster_next = next; |
| return; |
| } |
| |
| prev = this_cpu_read(*si->cluster_next_cpu); |
| /* |
| * Cross the swap address space size aligned trunk, choose |
| * another trunk randomly to avoid lock contention on swap |
| * address space if possible. |
| */ |
| if ((prev >> SWAP_ADDRESS_SPACE_SHIFT) != |
| (next >> SWAP_ADDRESS_SPACE_SHIFT)) { |
| /* No free swap slots available */ |
| if (si->highest_bit <= si->lowest_bit) |
| return; |
| next = si->lowest_bit + |
| prandom_u32_max(si->highest_bit - si->lowest_bit + 1); |
| next = ALIGN_DOWN(next, SWAP_ADDRESS_SPACE_PAGES); |
| next = max_t(unsigned int, next, si->lowest_bit); |
| } |
| this_cpu_write(*si->cluster_next_cpu, next); |
| } |
| |
| static int scan_swap_map_slots(struct swap_info_struct *si, |
| unsigned char usage, int nr, |
| swp_entry_t slots[]) |
| { |
| struct swap_cluster_info *ci; |
| unsigned long offset; |
| unsigned long scan_base; |
| unsigned long last_in_cluster = 0; |
| int latency_ration = LATENCY_LIMIT; |
| int n_ret = 0; |
| bool scanned_many = false; |
| |
| /* |
| * We try to cluster swap pages by allocating them sequentially |
| * in swap. Once we've allocated SWAPFILE_CLUSTER pages this |
| * way, however, we resort to first-free allocation, starting |
| * a new cluster. This prevents us from scattering swap pages |
| * all over the entire swap partition, so that we reduce |
| * overall disk seek times between swap pages. -- sct |
| * But we do now try to find an empty cluster. -Andrea |
| * And we let swap pages go all over an SSD partition. Hugh |
| */ |
| |
| si->flags += SWP_SCANNING; |
| /* |
| * Use percpu scan base for SSD to reduce lock contention on |
| * cluster and swap cache. For HDD, sequential access is more |
| * important. |
| */ |
| if (si->flags & SWP_SOLIDSTATE) |
| scan_base = this_cpu_read(*si->cluster_next_cpu); |
| else |
| scan_base = si->cluster_next; |
| offset = scan_base; |
| |
| /* SSD algorithm */ |
| if (si->cluster_info) { |
| if (!scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) |
| goto scan; |
| } else if (unlikely(!si->cluster_nr--)) { |
| if (si->pages - si->inuse_pages < SWAPFILE_CLUSTER) { |
| si->cluster_nr = SWAPFILE_CLUSTER - 1; |
| goto checks; |
| } |
| |
| spin_unlock(&si->lock); |
| |
| /* |
| * If seek is expensive, start searching for new cluster from |
| * start of partition, to minimize the span of allocated swap. |
| * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info |
| * case, just handled by scan_swap_map_try_ssd_cluster() above. |
| */ |
| scan_base = offset = si->lowest_bit; |
| last_in_cluster = offset + SWAPFILE_CLUSTER - 1; |
| |
| /* Locate the first empty (unaligned) cluster */ |
| for (; last_in_cluster <= si->highest_bit; offset++) { |
| if (si->swap_map[offset]) |
| last_in_cluster = offset + SWAPFILE_CLUSTER; |
| else if (offset == last_in_cluster) { |
| spin_lock(&si->lock); |
| offset -= SWAPFILE_CLUSTER - 1; |
| si->cluster_next = offset; |
| si->cluster_nr = SWAPFILE_CLUSTER - 1; |
| goto checks; |
| } |
| if (unlikely(--latency_ration < 0)) { |
| cond_resched(); |
| latency_ration = LATENCY_LIMIT; |
| } |
| } |
| |
| offset = scan_base; |
| spin_lock(&si->lock); |
| si->cluster_nr = SWAPFILE_CLUSTER - 1; |
| } |
| |
| checks: |
| if (si->cluster_info) { |
| while (scan_swap_map_ssd_cluster_conflict(si, offset)) { |
| /* take a break if we already got some slots */ |
| if (n_ret) |
| goto done; |
| if (!scan_swap_map_try_ssd_cluster(si, &offset, |
| &scan_base)) |
| goto scan; |
| } |
| } |
| if (!(si->flags & SWP_WRITEOK)) |
| goto no_page; |
| if (!si->highest_bit) |
| goto no_page; |
| if (offset > si->highest_bit) |
| scan_base = offset = si->lowest_bit; |
| |
| ci = lock_cluster(si, offset); |
| /* reuse swap entry of cache-only swap if not busy. */ |
| if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
| int swap_was_freed; |
| unlock_cluster(ci); |
| spin_unlock(&si->lock); |
| swap_was_freed = __try_to_reclaim_swap(si, offset, TTRS_ANYWAY); |
| spin_lock(&si->lock); |
| /* entry was freed successfully, try to use this again */ |
| if (swap_was_freed) |
| goto checks; |
| goto scan; /* check next one */ |
| } |
| |
| if (si->swap_map[offset]) { |
| unlock_cluster(ci); |
| if (!n_ret) |
| goto scan; |
| else |
| goto done; |
| } |
| si->swap_map[offset] = usage; |
| inc_cluster_info_page(si, si->cluster_info, offset); |
| unlock_cluster(ci); |
| |
| swap_range_alloc(si, offset, 1); |
| slots[n_ret++] = swp_entry(si->type, offset); |
| |
| /* got enough slots or reach max slots? */ |
| if ((n_ret == nr) || (offset >= si->highest_bit)) |
| goto done; |
| |
| /* search for next available slot */ |
| |
| /* time to take a break? */ |
| if (unlikely(--latency_ration < 0)) { |
| if (n_ret) |
| goto done; |
| spin_unlock(&si->lock); |
| cond_resched(); |
| spin_lock(&si->lock); |
| latency_ration = LATENCY_LIMIT; |
| } |
| |
| /* try to get more slots in cluster */ |
| if (si->cluster_info) { |
| if (scan_swap_map_try_ssd_cluster(si, &offset, &scan_base)) |
| goto checks; |
| } else if (si->cluster_nr && !si->swap_map[++offset]) { |
| /* non-ssd case, still more slots in cluster? */ |
| --si->cluster_nr; |
| goto checks; |
| } |
| |
| /* |
| * Even if there's no free clusters available (fragmented), |
| * try to scan a little more quickly with lock held unless we |
| * have scanned too many slots already. |
| */ |
| if (!scanned_many) { |
| unsigned long scan_limit; |
| |
| if (offset < scan_base) |
| scan_limit = scan_base; |
| else |
| scan_limit = si->highest_bit; |
| for (; offset <= scan_limit && --latency_ration > 0; |
| offset++) { |
| if (!si->swap_map[offset]) |
| goto checks; |
| } |
| } |
| |
| done: |
| set_cluster_next(si, offset + 1); |
| si->flags -= SWP_SCANNING; |
| return n_ret; |
| |
| scan: |
| spin_unlock(&si->lock); |
| while (++offset <= si->highest_bit) { |
| if (!si->swap_map[offset]) { |
| spin_lock(&si->lock); |
| goto checks; |
| } |
| if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
| spin_lock(&si->lock); |
| goto checks; |
| } |
| if (unlikely(--latency_ration < 0)) { |
| cond_resched(); |
| latency_ration = LATENCY_LIMIT; |
| scanned_many = true; |
| } |
| } |
| offset = si->lowest_bit; |
| while (offset < scan_base) { |
| if (!si->swap_map[offset]) { |
| spin_lock(&si->lock); |
| goto checks; |
| } |
| if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { |
| spin_lock(&si->lock); |
| goto checks; |
| } |
| if (unlikely(--latency_ration < 0)) { |
| cond_resched(); |
| latency_ration = LATENCY_LIMIT; |
| scanned_many = true; |
| } |
| offset++; |
| } |
| spin_lock(&si->lock); |
| |
| no_page: |
| si->flags -= SWP_SCANNING; |
| return n_ret; |
| } |
| |
| static int swap_alloc_cluster(struct swap_info_struct *si, swp_entry_t *slot) |
| { |
| unsigned long idx; |
| struct swap_cluster_info *ci; |
| unsigned long offset, i; |
| unsigned char *map; |
| |
| /* |
| * Should not even be attempting cluster allocations when huge |
| * page swap is disabled. Warn and fail the allocation. |
| */ |
| if (!IS_ENABLED(CONFIG_THP_SWAP)) { |
| VM_WARN_ON_ONCE(1); |
| return 0; |
| } |
| |
| if (cluster_list_empty(&si->free_clusters)) |
| return 0; |
| |
| idx = cluster_list_first(&si->free_clusters); |
| offset = idx * SWAPFILE_CLUSTER; |
| ci = lock_cluster(si, offset); |
| alloc_cluster(si, idx); |
| cluster_set_count_flag(ci, SWAPFILE_CLUSTER, CLUSTER_FLAG_HUGE); |
| |
| map = si->swap_map + offset; |
| for (i = 0; i < SWAPFILE_CLUSTER; i++) |
| map[i] = SWAP_HAS_CACHE; |
| unlock_cluster(ci); |
| swap_range_alloc(si, offset, SWAPFILE_CLUSTER); |
| *slot = swp_entry(si->type, offset); |
| |
| return 1; |
| } |
| |
| static void swap_free_cluster(struct swap_info_struct *si, unsigned long idx) |
| { |
| unsigned long offset = idx * SWAPFILE_CLUSTER; |
| struct swap_cluster_info *ci; |
| |
| ci = lock_cluster(si, offset); |
| memset(si->swap_map + offset, 0, SWAPFILE_CLUSTER); |
| cluster_set_count_flag(ci, 0, 0); |
| free_cluster(si, idx); |
| unlock_cluster(ci); |
| swap_range_free(si, offset, SWAPFILE_CLUSTER); |
| } |
| |
| static unsigned long scan_swap_map(struct swap_info_struct *si, |
| unsigned char usage) |
| { |
| swp_entry_t entry; |
| int n_ret; |
| |
| n_ret = scan_swap_map_slots(si, usage, 1, &entry); |
| |
| if (n_ret) |
| return swp_offset(entry); |
| else |
| return 0; |
| |
| } |
| |
| int get_swap_pages(int n_goal, swp_entry_t swp_entries[], int entry_size) |
| { |
| unsigned long size = swap_entry_size(entry_size); |
| struct swap_info_struct *si, *next; |
| long avail_pgs; |
| int n_ret = 0; |
| int node; |
| |
| /* Only single cluster request supported */ |
| WARN_ON_ONCE(n_goal > 1 && size == SWAPFILE_CLUSTER); |
| |
| avail_pgs = atomic_long_read(&nr_swap_pages) / size; |
| if (avail_pgs <= 0) |
| goto noswap; |
| |
| n_goal = min3((long)n_goal, (long)SWAP_BATCH, avail_pgs); |
| |
| atomic_long_sub(n_goal * size, &nr_swap_pages); |
| |
| spin_lock(&swap_avail_lock); |
| |
| start_over: |
| node = numa_node_id(); |
| plist_for_each_entry_safe(si, next, &swap_avail_heads[node], avail_lists[node]) { |
| /* requeue si to after same-priority siblings */ |
| plist_requeue(&si->avail_lists[node], &swap_avail_heads[node]); |
| spin_unlock(&swap_avail_lock); |
| spin_lock(&si->lock); |
| if (!si->highest_bit || !(si->flags & SWP_WRITEOK)) { |
| spin_lock(&swap_avail_lock); |
| if (plist_node_empty(&si->avail_lists[node])) { |
| spin_unlock(&si->lock); |
| goto nextsi; |
| } |
| WARN(!si->highest_bit, |
| "swap_info %d in list but !highest_bit\n", |
| si->type); |
| WARN(!(si->flags & SWP_WRITEOK), |
| "swap_info %d in list but !SWP_WRITEOK\n", |
| si->type); |
| __del_from_avail_list(si); |
| spin_unlock(&si->lock); |
| goto nextsi; |
| } |
| if (size == SWAPFILE_CLUSTER) { |
| if (!(si->flags & SWP_FS)) |
| n_ret = swap_alloc_cluster(si, swp_entries); |
| } else |
| n_ret = scan_swap_map_slots(si, SWAP_HAS_CACHE, |
| n_goal, swp_entries); |
| spin_unlock(&si->lock); |
| if (n_ret || size == SWAPFILE_CLUSTER) |
| goto check_out; |
| pr_debug("scan_swap_map of si %d failed to find offset\n", |
| si->type); |
| |
| spin_lock(&swap_avail_lock); |
| nextsi: |
| /* |
| * if we got here, it's likely that si was almost full before, |
| * and since scan_swap_map() can drop the si->lock, multiple |
| * callers probably all tried to get a page from the same si |
| * and it filled up before we could get one; or, the si filled |
| * up between us dropping swap_avail_lock and taking si->lock. |
| * Since we dropped the swap_avail_lock, the swap_avail_head |
| * list may have been modified; so if next is still in the |
| * swap_avail_head list then try it, otherwise start over |
| * if we have not gotten any slots. |
| */ |
| if (plist_node_empty(&next->avail_lists[node])) |
| goto start_over; |
| } |
| |
| spin_unlock(&swap_avail_lock); |
| |
| check_out: |
| if (n_ret < n_goal) |
| atomic_long_add((long)(n_goal - n_ret) * size, |
| &nr_swap_pages); |
| noswap: |
| return n_ret; |
| } |
| |
| /* The only caller of this function is now suspend routine */ |
| swp_entry_t get_swap_page_of_type(int type) |
| { |
| struct swap_info_struct *si = swap_type_to_swap_info(type); |
| pgoff_t offset; |
| |
| if (!si) |
| goto fail; |
| |
| spin_lock(&si->lock); |
| if (si->flags & SWP_WRITEOK) { |
| atomic_long_dec(&nr_swap_pages); |
| /* This is called for allocating swap entry, not cache */ |
| offset = scan_swap_map(si, 1); |
| if (offset) { |
| spin_unlock(&si->lock); |
| return swp_entry(type, offset); |
| } |
| atomic_long_inc(&nr_swap_pages); |
| } |
| spin_unlock(&si->lock); |
| fail: |
| return (swp_entry_t) {0}; |
| } |
| |
| static struct swap_info_struct *__swap_info_get(swp_entry_t entry) |
| { |
| struct swap_info_struct *p; |
| unsigned long offset; |
| |
| if (!entry.val) |
| goto out; |
| p = swp_swap_info(entry); |
| if (!p) |
| goto bad_nofile; |
| if (!(p->flags & SWP_USED)) |
| goto bad_device; |
| offset = swp_offset(entry); |
| if (offset >= p->max) |
| goto bad_offset; |
| return p; |
| |
| bad_offset: |
| pr_err("swap_info_get: %s%08lx\n", Bad_offset, entry.val); |
| goto out; |
| bad_device: |
| pr_err("swap_info_get: %s%08lx\n", Unused_file, entry.val); |
| goto out; |
| bad_nofile: |
| pr_err("swap_info_get: %s%08lx\n", Bad_file, entry.val); |
| out: |
| return NULL; |
| } |
| |
| static struct swap_info_struct *_swap_info_get(swp_entry_t entry) |
| { |
| struct swap_info_struct *p; |
| |
| p = __swap_info_get(entry); |
| if (!p) |
| goto out; |
| if (!p->swap_map[swp_offset(entry)]) |
| goto bad_free; |
| return p; |
| |
| bad_free: |
| pr_err("swap_info_get: %s%08lx\n", Unused_offset, entry.val); |
| goto out; |
| out: |
| return NULL; |
| } |
| |
| static struct swap_info_struct *swap_info_get(swp_entry_t entry) |
| { |
| struct swap_info_struct *p; |
| |
| p = _swap_info_get(entry); |
| if (p) |
| spin_lock(&p->lock); |
| return p; |
| } |
| |
| static struct swap_info_struct *swap_info_get_cont(swp_entry_t entry, |
| struct swap_info_struct *q) |
| { |
| struct swap_info_struct *p; |
| |
| p = _swap_info_get(entry); |
| |
| if (p != q) { |
| if (q != NULL) |
| spin_unlock(&q->lock); |
| if (p != NULL) |
| spin_lock(&p->lock); |
| } |
| return p; |
| } |
| |
| static unsigned char __swap_entry_free_locked(struct swap_info_struct *p, |
| unsigned long offset, |
| unsigned char usage) |
| { |
| unsigned char count; |
| unsigned char has_cache; |
| |
| count = p->swap_map[offset]; |
| |
| has_cache = count & SWAP_HAS_CACHE; |
| count &= ~SWAP_HAS_CACHE; |
| |
| if (usage == SWAP_HAS_CACHE) { |
| VM_BUG_ON(!has_cache); |
| has_cache = 0; |
| } else if (count == SWAP_MAP_SHMEM) { |
| /* |
| * Or we could insist on shmem.c using a special |
| * swap_shmem_free() and free_shmem_swap_and_cache()... |
| */ |
| count = 0; |
| } else if ((count & ~COUNT_CONTINUED) <= SWAP_MAP_MAX) { |
| if (count == COUNT_CONTINUED) { |
| if (swap_count_continued(p, offset, count)) |
| count = SWAP_MAP_MAX | COUNT_CONTINUED; |
| else |
| count = SWAP_MAP_MAX; |
| } else |
| count--; |
| } |
| |
| usage = count | has_cache; |
| p->swap_map[offset] = usage ? : SWAP_HAS_CACHE; |
| |
| return usage; |
| } |
| |
| /* |
| * Check whether swap entry is valid in the swap device. If so, |
| * return pointer to swap_info_struct, and keep the swap entry valid |
| * via preventing the swap device from being swapoff, until |
| * put_swap_device() is called. Otherwise return NULL. |
| * |
| * The entirety of the RCU read critical section must come before the |
| * return from or after the call to synchronize_rcu() in |
| * enable_swap_info() or swapoff(). So if "si->flags & SWP_VALID" is |
| * true, the si->map, si->cluster_info, etc. must be valid in the |
| * critical section. |
| * |
| * Notice that swapoff or swapoff+swapon can still happen before the |
| * rcu_read_lock() in get_swap_device() or after the rcu_read_unlock() |
| * in put_swap_device() if there isn't any other way to prevent |
| * swapoff, such as page lock, page table lock, etc. The caller must |
| * be prepared for that. For example, the following situation is |
| * possible. |
| * |
| * CPU1 CPU2 |
| * do_swap_page() |
| * ... swapoff+swapon |
| * __read_swap_cache_async() |
| * swapcache_prepare() |
| * __swap_duplicate() |
| * // check swap_map |
| * // verify PTE not changed |
| * |
| * In __swap_duplicate(), the swap_map need to be checked before |
| * changing partly because the specified swap entry may be for another |
| * swap device which has been swapoff. And in do_swap_page(), after |
| * the page is read from the swap device, the PTE is verified not |
| * changed with the page table locked to check whether the swap device |
| * has been swapoff or swapoff+swapon. |
| */ |
| struct swap_info_struct *get_swap_device(swp_entry_t entry) |
| { |
| struct swap_info_struct *si; |
| unsigned long offset; |
| |
| if (!entry.val) |
| goto out; |
| si = swp_swap_info(entry); |
| if (!si) |
| goto bad_nofile; |
| |
| rcu_read_lock(); |
| if (!(si->flags & SWP_VALID)) |
| goto unlock_out; |
| offset = swp_offset(entry); |
| if (offset >= si->max) |
| goto unlock_out; |
| |
| return si; |
| bad_nofile: |
| pr_err("%s: %s%08lx\n", __func__, Bad_file, entry.val); |
| out: |
| return NULL; |
| unlock_out: |
| rcu_read_unlock(); |
| return NULL; |
| } |
| |
| static unsigned char __swap_entry_free(struct swap_info_struct *p, |
| swp_entry_t entry) |
| { |
| struct swap_cluster_info *ci; |
| unsigned long offset = swp_offset(entry); |
| unsigned char usage; |
| |
| ci = lock_cluster_or_swap_info(p, offset); |
| usage = __swap_entry_free_locked(p, offset, 1); |
| unlock_cluster_or_swap_info(p, ci); |
| if (!usage) |
| free_swap_slot(entry); |
| |
| return usage; |
| } |
| |
| static void swap_entry_free(struct swap_info_struct *p, swp_entry_t entry) |
| { |
| struct swap_cluster_info *ci; |
| unsigned long offset = swp_offset(entry); |
| unsigned char count; |
| |
| ci = lock_cluster(p, offset); |
| count = p->swap_map[offset]; |
| VM_BUG_ON(count != SWAP_HAS_CACHE); |
| p->swap_map[offset] = 0; |
| dec_cluster_info_page(p, p->cluster_info, offset); |
| unlock_cluster(ci); |
| |
| mem_cgroup_uncharge_swap(entry, 1); |
| swap_range_free(p, offset, 1); |
| } |
| |
| /* |
| * Caller has made sure that the swap device corresponding to entry |
| * is still around or has not been recycled. |
| */ |
| void swap_free(swp_entry_t entry) |
| { |
| struct swap_info_struct *p; |
| |
| p = _swap_info_get(entry); |
| if (p) |
| __swap_entry_free(p, entry); |
| } |
| |
| /* |
| * Called after dropping swapcache to decrease refcnt to swap entries. |
| */ |
| void put_swap_page(struct page *page, swp_entry_t entry) |
| { |
| unsigned long offset = swp_offset(entry); |
| unsigned long idx = offset / SWAPFILE_CLUSTER; |
| struct swap_cluster_info *ci; |
| struct swap_info_struct *si; |
| unsigned char *map; |
| unsigned int i, free_entries = 0; |
| unsigned char val; |
| int size = swap_entry_size(hpage_nr_pages(page)); |
| |
| si = _swap_info_get(entry); |
| if (!si) |
| return; |
| |
| ci = lock_cluster_or_swap_info(si, offset); |
| if (size == SWAPFILE_CLUSTER) { |
| VM_BUG_ON(!cluster_is_huge(ci)); |
| map = si->swap_map + offset; |
| for (i = 0; i < SWAPFILE_CLUSTER; i++) { |
| val = map[i]; |
| VM_BUG_ON(!(val & SWAP_HAS_CACHE)); |
| if (val == SWAP_HAS_CACHE) |
| free_entries++; |
| } |
| cluster_clear_huge(ci); |
| if (free_entries == SWAPFILE_CLUSTER) { |
| unlock_cluster_or_swap_info(si, ci); |
| spin_lock(&si->lock); |
| mem_cgroup_uncharge_swap(entry, SWAPFILE_CLUSTER); |
| swap_free_cluster(si, idx); |
| spin_unlock(&si->lock); |
| return; |
| } |
| } |
| for (i = 0; i < size; i++, entry.val++) { |
| if (!__swap_entry_free_locked(si, offset + i, SWAP_HAS_CACHE)) { |
| unlock_cluster_or_swap_info(si, ci); |
| free_swap_slot(entry); |
| if (i == size - 1) |
| return; |
| lock_cluster_or_swap_info(si, offset); |
| } |
| } |
| unlock_cluster_or_swap_info(si, ci); |
| } |
| |
| #ifdef CONFIG_THP_SWAP |
| int split_swap_cluster(swp_entry_t entry) |
| { |
| struct swap_info_struct *si; |
| struct swap_cluster_info *ci; |
| unsigned long offset = swp_offset(entry); |
| |
| si = _swap_info_get(entry); |
| if (!si) |
| return -EBUSY; |
| ci = lock_cluster(si, offset); |
| cluster_clear_huge(ci); |
| unlock_cluster(ci); |
| return 0; |
| } |
| #endif |
| |
| static int swp_entry_cmp(const void *ent1, const void *ent2) |
| { |
| const swp_entry_t *e1 = ent1, *e2 = ent2; |
| |
| return (int)swp_type(*e1) - (int)swp_type(*e2); |
| } |
| |
| void swapcache_free_entries(swp_entry_t *entries, int n) |
| { |
| struct swap_info_struct *p, *prev; |
| int i; |
| |
| if (n <= 0) |
| return; |
| |
| prev = NULL; |
| p = NULL; |
| |
| /* |
| * Sort swap entries by swap device, so each lock is only taken once. |
| * nr_swapfiles isn't absolutely correct, but the overhead of sort() is |
| * so low that it isn't necessary to optimize further. |
| */ |
| if (nr_swapfiles > 1) |
| sort(entries, n, sizeof(entries[0]), swp_entry_cmp, NULL); |
| for (i = 0; i < n; ++i) { |
| p = swap_info_get_cont(entries[i], prev); |
| if (p) |
| swap_entry_free(p, entries[i]); |
| prev = p; |
| } |
| if (p) |
| spin_unlock(&p->lock); |
| } |
| |
| /* |
| * How many references to page are currently swapped out? |
| * This does not give an exact answer when swap count is continued, |
| * but does include the high COUNT_CONTINUED flag to allow for that. |
| */ |
| int page_swapcount(struct page *page) |
| { |
| int count = 0; |
| struct swap_info_struct *p; |
| struct swap_cluster_info *ci; |
| swp_entry_t entry; |
| unsigned long offset; |
| |
| entry.val = page_private(page); |
| p = _swap_info_get(entry); |
| if (p) { |
| offset = swp_offset(entry); |
| ci = lock_cluster_or_swap_info(p, offset); |
| count = swap_count(p->swap_map[offset]); |
| unlock_cluster_or_swap_info(p, ci); |
| } |
| return count; |
| } |
| |
| int __swap_count(swp_entry_t entry) |
| { |
| struct swap_info_struct *si; |
| pgoff_t offset = swp_offset(entry); |
| int count = 0; |
| |
| si = get_swap_device(entry); |
| if (si) { |
| count = swap_count(si->swap_map[offset]); |
| put_swap_device(si); |
| } |
| return count; |
| } |
| |
| static int swap_swapcount(struct swap_info_struct *si, swp_entry_t entry) |
| { |
| int count = 0; |
| pgoff_t offset = swp_offset(entry); |
| struct swap_cluster_info *ci; |
| |
| ci = lock_cluster_or_swap_info(si, offset); |
| count = swap_count(si->swap_map[offset]); |
| unlock_cluster_or_swap_info(si, ci); |
| return count; |
| } |
| |
| /* |
| * How many references to @entry are currently swapped out? |
| * This does not give an exact answer when swap count is continued, |
| * but does include the high COUNT_CONTINUED flag to allow for that. |
| */ |
| int __swp_swapcount(swp_entry_t entry) |
| { |
| int count = 0; |
| struct swap_info_struct *si; |
| |
| si = get_swap_device(entry); |
| if (si) { |
| count = swap_swapcount(si, entry); |
| put_swap_device(si); |
| } |
| return count; |
| } |
| |
| /* |
| * How many references to @entry are currently swapped out? |
| * This considers COUNT_CONTINUED so it returns exact answer. |
| */ |
| int swp_swapcount(swp_entry_t entry) |
| { |
| int count, tmp_count, n; |
| struct swap_info_struct *p; |
| struct swap_cluster_info *ci; |
| struct page *page; |
| pgoff_t offset; |
| unsigned char *map; |
| |
| p = _swap_info_get(entry); |
| if (!p) |
| return 0; |
| |
| offset = swp_offset(entry); |
| |
| ci = lock_cluster_or_swap_info(p, offset); |
| |
| count = swap_count(p->swap_map[offset]); |
| if (!(count & COUNT_CONTINUED)) |
| goto out; |
| |
| count &= ~COUNT_CONTINUED; |
| n = SWAP_MAP_MAX + 1; |
| |
| page = vmalloc_to_page(p->swap_map + offset); |
| offset &= ~PAGE_MASK; |
| VM_BUG_ON(page_private(page) != SWP_CONTINUED); |
| |
| do { |
| page = list_next_entry(page, lru); |
| map = kmap_atomic(page); |
| tmp_count = map[offset]; |
| kunmap_atomic(map); |
| |
| count += (tmp_count & ~COUNT_CONTINUED) * n; |
| n *= (SWAP_CONT_MAX + 1); |
| } while (tmp_count & COUNT_CONTINUED); |
| out: |
| unlock_cluster_or_swap_info(p, ci); |
| return count; |
| } |
| |
| static bool swap_page_trans_huge_swapped(struct swap_info_struct *si, |
| swp_entry_t entry) |
| { |
| struct swap_cluster_info *ci; |
| unsigned char *map = si->swap_map; |
| unsigned long roffset = swp_offset(entry); |
| unsigned long offset = round_down(roffset, SWAPFILE_CLUSTER); |
| int i; |
| bool ret = false; |
| |
| ci = lock_cluster_or_swap_info(si, offset); |
| if (!ci || !cluster_is_huge(ci)) { |
| if (swap_count(map[roffset])) |
| ret = true; |
| goto unlock_out; |
| } |
| for (i = 0; i < SWAPFILE_CLUSTER; i++) { |
| if (swap_count(map[offset + i])) { |
| ret = true; |
| break; |
| } |
| } |
| unlock_out: |
| unlock_cluster_or_swap_info(si, ci); |
| return ret; |
| } |
| |
| static bool page_swapped(struct page *page) |
| { |
| swp_entry_t entry; |
| struct swap_info_struct *si; |
| |
| if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) |
| return page_swapcount(page) != 0; |
| |
| page = compound_head(page); |
| entry.val = page_private(page); |
| si = _swap_info_get(entry); |
| if (si) |
| return swap_page_trans_huge_swapped(si, entry); |
| return false; |
| } |
| |
| static int page_trans_huge_map_swapcount(struct page *page, int *total_mapcount, |
| int *total_swapcount) |
| { |
| int i, map_swapcount, _total_mapcount, _total_swapcount; |
| unsigned long offset = 0; |
| struct swap_info_struct *si; |
| struct swap_cluster_info *ci = NULL; |
| unsigned char *map = NULL; |
| int mapcount, swapcount = 0; |
| |
| /* hugetlbfs shouldn't call it */ |
| VM_BUG_ON_PAGE(PageHuge(page), page); |
| |
| if (!IS_ENABLED(CONFIG_THP_SWAP) || likely(!PageTransCompound(page))) { |
| mapcount = page_trans_huge_mapcount(page, total_mapcount); |
| if (PageSwapCache(page)) |
| swapcount = page_swapcount(page); |
| if (total_swapcount) |
| *total_swapcount = swapcount; |
| return mapcount + swapcount; |
| } |
| |
| page = compound_head(page); |
| |
| _total_mapcount = _total_swapcount = map_swapcount = 0; |
| if (PageSwapCache(page)) { |
| swp_entry_t entry; |
| |
| entry.val = page_private(page); |
| si = _swap_info_get(entry); |
| if (si) { |
| map = si->swap_map; |
| offset = swp_offset(entry); |
| } |
| } |
| if (map) |
| ci = lock_cluster(si, offset); |
| for (i = 0; i < HPAGE_PMD_NR; i++) { |
| mapcount = atomic_read(&page[i]._mapcount) + 1; |
| _total_mapcount += mapcount; |
| if (map) { |
| swapcount = swap_count(map[offset + i]); |
| _total_swapcount += swapcount; |
| } |
| map_swapcount = max(map_swapcount, mapcount + swapcount); |
| } |
| unlock_cluster(ci); |
| if (PageDoubleMap(page)) { |
| map_swapcount -= 1; |
| _total_mapcount -= HPAGE_PMD_NR; |
| } |
| mapcount = compound_mapcount(page); |
| map_swapcount += mapcount; |
| _total_mapcount += mapcount; |
| if (total_mapcount) |
| *total_mapcount = _total_mapcount; |
| if (total_swapcount) |
| *total_swapcount = _total_swapcount; |
| |
| return map_swapcount; |
| } |
| |
| /* |
| * We can write to an anon page without COW if there are no other references |
| * to it. And as a side-effect, free up its swap: because the old content |
| * on disk will never be read, and seeking back there to write new content |
| * later would only waste time away from clustering. |
| * |
| * NOTE: total_map_swapcount should not be relied upon by the caller if |
| * reuse_swap_page() returns false, but it may be always overwritten |
| * (see the other implementation for CONFIG_SWAP=n). |
| */ |
| bool reuse_swap_page(struct page *page, int *total_map_swapcount) |
| { |
| int count, total_mapcount, total_swapcount; |
| |
| VM_BUG_ON_PAGE(!PageLocked(page), page); |
| if (unlikely(PageKsm(page))) |
| return false; |
| count = page_trans_huge_map_swapcount(page, &total_mapcount, |
| &total_swapcount); |
| if (total_map_swapcount) |
| *total_map_swapcount = total_mapcount + total_swapcount; |
| if (count == 1 && PageSwapCache(page) && |
| (likely(!PageTransCompound(page)) || |
| /* The remaining swap count will be freed soon */ |
| total_swapcount == page_swapcount(page))) { |
| if (!PageWriteback(page)) { |
| page = compound_head(page); |
| delete_from_swap_cache(page); |
| SetPageDirty(page); |
| } else { |
| swp_entry_t entry; |
| struct swap_info_struct *p; |
| |
| entry.val = page_private(page); |
| p = swap_info_get(entry); |
| if (p->flags & SWP_STABLE_WRITES) { |
| spin_unlock(&p->lock); |
| return false; |
| } |
| spin_unlock(&p->lock); |
| } |
| } |
| |
| return count <= 1; |
| } |
| |
| /* |
| * If swap is getting full, or if there are no more mappings of this page, |
| * then try_to_free_swap is called to free its swap space. |
| */ |
| int try_to_free_swap(struct page *page) |
| { |
| VM_BUG_ON_PAGE(!PageLocked(page), page); |
| |
| if (!PageSwapCache(page)) |
| return 0; |
| if (PageWriteback(page)) |
| return 0; |
| if (page_swapped(page)) |
| return 0; |
| |
| /* |
| * Once hibernation has begun to create its image of memory, |
| * there's a danger that one of the calls to try_to_free_swap() |
| * - most probably a call from __try_to_reclaim_swap() while |
| * hibernation is allocating its own swap pages for the image, |
| * but conceivably even a call from memory reclaim - will free |
| * the swap from a page which has already been recorded in the |
| * image as a clean swapcache page, and then reuse its swap for |
| * another page of the image. On waking from hibernation, the |
| * original page might be freed under memory pressure, then |
| * later read back in from swap, now with the wrong data. |
| * |
| * Hibernation suspends storage while it is writing the image |
| * to disk so check that here. |
| */ |
| if (pm_suspended_storage()) |
| return 0; |
| |
| page = compound_head(page); |
| delete_from_swap_cache(page); |
| SetPageDirty(page); |
| return 1; |
| } |
| |
| /* |
| * Free the swap entry like above, but also try to |
| * free the page cache entry if it is the last user. |
| */ |
| int free_swap_and_cache(swp_entry_t entry) |
| { |
| struct swap_info_struct *p; |
| unsigned char count; |
| |
| if (non_swap_entry(entry)) |
| return 1; |
| |
| p = _swap_info_get(entry); |
| if (p) { |
| count = __swap_entry_free(p, entry); |
| if (count == SWAP_HAS_CACHE && |
| !swap_page_trans_huge_swapped(p, entry)) |
| __try_to_reclaim_swap(p, swp_offset(entry), |
| TTRS_UNMAPPED | TTRS_FULL); |
| } |
| return p != NULL; |
| } |
| |
| #ifdef CONFIG_HIBERNATION |
| /* |
| * Find the swap type that corresponds to given device (if any). |
| * |
| * @offset - number of the PAGE_SIZE-sized block of the device, starting |
| * from 0, in which the swap header is expected to be located. |
| * |
| * This is needed for the suspend to disk (aka swsusp). |
| */ |
| int swap_type_of(dev_t device, sector_t offset, struct block_device **bdev_p) |
| { |
| struct block_device *bdev = NULL; |
| int type; |
| |
| if (device) |
| bdev = bdget(device); |
| |
| spin_lock(&swap_lock); |
| for (type = 0; type < nr_swapfiles; type++) { |
| struct swap_info_struct *sis = swap_info[type]; |
| |
| if (!(sis->flags & SWP_WRITEOK)) |
| continue; |
| |
| if (!bdev) { |
| if (bdev_p) |
| *bdev_p = bdgrab(sis->bdev); |
| |
| spin_unlock(&swap_lock); |
| return type; |
| } |
| if (bdev == sis->bdev) { |
| struct swap_extent *se = first_se(sis); |
| |
| if (se->start_block == offset) { |
| if (bdev_p) |
| *bdev_p = bdgrab(sis->bdev); |
| |
| spin_unlock(&swap_lock); |
| bdput(bdev); |
| return type; |
| } |
| } |
| } |
| spin_unlock(&swap_lock); |
| if (bdev) |
| bdput(bdev); |
| |
| return -ENODEV; |
| } |
| |
| /* |
| * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev |
| * corresponding to given index in swap_info (swap type). |
| */ |
| sector_t swapdev_block(int type, pgoff_t offset) |
| { |
| struct block_device *bdev; |
| struct swap_info_struct *si = swap_type_to_swap_info(type); |
| |
| if (!si || !(si->flags & SWP_WRITEOK)) |
| return 0; |
| return map_swap_entry(swp_entry(type, offset), &bdev); |
| } |
| |
| /* |
| * Return either the total number of swap pages of given type, or the number |
| * of free pages of that type (depending on @free) |
| * |
| * This is needed for software suspend |
| */ |
| unsigned int count_swap_pages(int type, int free) |
| { |
| unsigned int n = 0; |
| |
| spin_lock(&swap_lock); |
| if ((unsigned int)type < nr_swapfiles) { |
| struct swap_info_struct *sis = swap_info[type]; |
| |
| spin_lock(&sis->lock); |
| if (sis->flags & SWP_WRITEOK) { |
| n = sis->pages; |
| if (free) |
| n -= sis->inuse_pages; |
| } |
| spin_unlock(&sis->lock); |
| } |
| spin_unlock(&swap_lock); |
| return n; |
| } |
| #endif /* CONFIG_HIBERNATION */ |
| |
| static inline int pte_same_as_swp(pte_t pte, pte_t swp_pte) |
| { |
| return pte_same(pte_swp_clear_soft_dirty(pte), swp_pte); |
| } |
| |
| /* |
| * No need to decide whether this PTE shares the swap entry with others, |
| * just let do_wp_page work it out if a write is requested later - to |
| * force COW, vm_page_prot omits write permission from any private vma. |
| */ |
| static int unuse_pte(struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long addr, swp_entry_t entry, struct page *page) |
| { |
| struct page *swapcache; |
| spinlock_t *ptl; |
| pte_t *pte; |
| int ret = 1; |
| |
| swapcache = page; |
| page = ksm_might_need_to_copy(page, vma, addr); |
| if (unlikely(!page)) |
| return -ENOMEM; |
| |
| pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl); |
| if (unlikely(!pte_same_as_swp(*pte, swp_entry_to_pte(entry)))) { |
| ret = 0; |
| goto out; |
| } |
| |
| dec_mm_counter(vma->vm_mm, MM_SWAPENTS); |
| inc_mm_counter(vma->vm_mm, MM_ANONPAGES); |
| get_page(page); |
| set_pte_at(vma->vm_mm, addr, pte, |
| pte_mkold(mk_pte(page, vma->vm_page_prot))); |
| if (page == swapcache) { |
| page_add_anon_rmap(page, vma, addr, false); |
| } else { /* ksm created a completely new copy */ |
| page_add_new_anon_rmap(page, vma, addr, false); |
| lru_cache_add_active_or_unevictable(page, vma); |
| } |
| swap_free(entry); |
| /* |
| * Move the page to the active list so it is not |
| * immediately swapped out again after swapon. |
| */ |
| activate_page(page); |
| out: |
| pte_unmap_unlock(pte, ptl); |
| if (page != swapcache) { |
| unlock_page(page); |
| put_page(page); |
| } |
| return ret; |
| } |
| |
| static int unuse_pte_range(struct vm_area_struct *vma, pmd_t *pmd, |
| unsigned long addr, unsigned long end, |
| unsigned int type, bool frontswap, |
| unsigned long *fs_pages_to_unuse) |
| { |
| struct page *page; |
| swp_entry_t entry; |
| pte_t *pte; |
| struct swap_info_struct *si; |
| unsigned long offset; |
| int ret = 0; |
| volatile unsigned char *swap_map; |
| |
| si = swap_info[type]; |
| pte = pte_offset_map(pmd, addr); |
| do { |
| struct vm_fault vmf; |
| |
| if (!is_swap_pte(*pte)) |
| continue; |
| |
| entry = pte_to_swp_entry(*pte); |
| if (swp_type(entry) != type) |
| continue; |
| |
| offset = swp_offset(entry); |
| if (frontswap && !frontswap_test(si, offset)) |
| continue; |
| |
| pte_unmap(pte); |
| swap_map = &si->swap_map[offset]; |
| page = lookup_swap_cache(entry, vma, addr); |
| if (!page) { |
| vmf.vma = vma; |
| vmf.address = addr; |
| vmf.pmd = pmd; |
| page = swapin_readahead(entry, GFP_HIGHUSER_MOVABLE, |
| &vmf); |
| } |
| if (!page) { |
| if (*swap_map == 0 || *swap_map == SWAP_MAP_BAD) |
| goto try_next; |
| return -ENOMEM; |
| } |
| |
| lock_page(page); |
| wait_on_page_writeback(page); |
| ret = unuse_pte(vma, pmd, addr, entry, page); |
| if (ret < 0) { |
| unlock_page(page); |
| put_page(page); |
| goto out; |
| } |
| |
| try_to_free_swap(page); |
| unlock_page(page); |
| put_page(page); |
| |
| if (*fs_pages_to_unuse && !--(*fs_pages_to_unuse)) { |
| ret = FRONTSWAP_PAGES_UNUSED; |
| goto out; |
| } |
| try_next: |
| pte = pte_offset_map(pmd, addr); |
| } while (pte++, addr += PAGE_SIZE, addr != end); |
| pte_unmap(pte - 1); |
| |
| ret = 0; |
| out: |
| return ret; |
| } |
| |
| static inline int unuse_pmd_range(struct vm_area_struct *vma, pud_t *pud, |
| unsigned long addr, unsigned long end, |
| unsigned int type, bool frontswap, |
| unsigned long *fs_pages_to_unuse) |
| { |
| pmd_t *pmd; |
| unsigned long next; |
| int ret; |
| |
| pmd = pmd_offset(pud, addr); |
| do { |
| cond_resched(); |
| next = pmd_addr_end(addr, end); |
| if (pmd_none_or_trans_huge_or_clear_bad(pmd)) |
| continue; |
| ret = unuse_pte_range(vma, pmd, addr, next, type, |
| frontswap, fs_pages_to_unuse); |
| if (ret) |
| return ret; |
| } while (pmd++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int unuse_pud_range(struct vm_area_struct *vma, p4d_t *p4d, |
| unsigned long addr, unsigned long end, |
| unsigned int type, bool frontswap, |
| unsigned long *fs_pages_to_unuse) |
| { |
| pud_t *pud; |
| unsigned long next; |
| int ret; |
| |
| pud = pud_offset(p4d, addr); |
| do { |
| next = pud_addr_end(addr, end); |
| if (pud_none_or_clear_bad(pud)) |
| continue; |
| ret = unuse_pmd_range(vma, pud, addr, next, type, |
| frontswap, fs_pages_to_unuse); |
| if (ret) |
| return ret; |
| } while (pud++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static inline int unuse_p4d_range(struct vm_area_struct *vma, pgd_t *pgd, |
| unsigned long addr, unsigned long end, |
| unsigned int type, bool frontswap, |
| unsigned long *fs_pages_to_unuse) |
| { |
| p4d_t *p4d; |
| unsigned long next; |
| int ret; |
| |
| p4d = p4d_offset(pgd, addr); |
| do { |
| next = p4d_addr_end(addr, end); |
| if (p4d_none_or_clear_bad(p4d)) |
| continue; |
| ret = unuse_pud_range(vma, p4d, addr, next, type, |
| frontswap, fs_pages_to_unuse); |
| if (ret) |
| return ret; |
| } while (p4d++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static int unuse_vma(struct vm_area_struct *vma, unsigned int type, |
| bool frontswap, unsigned long *fs_pages_to_unuse) |
| { |
| pgd_t *pgd; |
| unsigned long addr, end, next; |
| int ret; |
| |
| addr = vma->vm_start; |
| end = vma->vm_end; |
| |
| pgd = pgd_offset(vma->vm_mm, addr); |
| do { |
| next = pgd_addr_end(addr, end); |
| if (pgd_none_or_clear_bad(pgd)) |
| continue; |
| ret = unuse_p4d_range(vma, pgd, addr, next, type, |
| frontswap, fs_pages_to_unuse); |
| if (ret) |
| return ret; |
| } while (pgd++, addr = next, addr != end); |
| return 0; |
| } |
| |
| static int unuse_mm(struct mm_struct *mm, unsigned int type, |
| bool frontswap, unsigned long *fs_pages_to_unuse) |
| { |
| struct vm_area_struct *vma; |
| int ret = 0; |
| |
| down_read(&mm->mmap_sem); |
| for (vma = mm->mmap; vma; vma = vma->vm_next) { |
| if (vma->anon_vma) { |
| ret = unuse_vma(vma, type, frontswap, |
| fs_pages_to_unuse); |
| if (ret) |
| break; |
| } |
| cond_resched(); |
| } |
| up_read(&mm->mmap_sem); |
| return ret; |
| } |
| |
| /* |
| * Scan swap_map (or frontswap_map if frontswap parameter is true) |
| * from current position to next entry still in use. Return 0 |
| * if there are no inuse entries after prev till end of the map. |
| */ |
| static unsigned int find_next_to_unuse(struct swap_info_struct *si, |
| unsigned int prev, bool frontswap) |
| { |
| unsigned int i; |
| unsigned char count; |
| |
| /* |
| * No need for swap_lock here: we're just looking |
| * for whether an entry is in use, not modifying it; false |
| * hits are okay, and sys_swapoff() has already prevented new |
| * allocations from this area (while holding swap_lock). |
| */ |
| for (i = prev + 1; i < si->max; i++) { |
| count = READ_ONCE(si->swap_map[i]); |
| if (count && swap_count(count) != SWAP_MAP_BAD) |
| if (!frontswap || frontswap_test(si, i)) |
| break; |
| if ((i % LATENCY_LIMIT) == 0) |
| cond_resched(); |
| } |
| |
| if (i == si->max) |
| i = 0; |
| |
| return i; |
| } |
| |
| /* |
| * If the boolean frontswap is true, only unuse pages_to_unuse pages; |
| * pages_to_unuse==0 means all pages; ignored if frontswap is false |
| */ |
| int try_to_unuse(unsigned int type, bool frontswap, |
| unsigned long pages_to_unuse) |
| { |
| struct mm_struct *prev_mm; |
| struct mm_struct *mm; |
| struct list_head *p; |
| int retval = 0; |
| struct swap_info_struct *si = swap_info[type]; |
| struct page *page; |
| swp_entry_t entry; |
| unsigned int i; |
| |
| if (!READ_ONCE(si->inuse_pages)) |
| return 0; |
| |
| if (!frontswap) |
| pages_to_unuse = 0; |
| |
| retry: |
| retval = shmem_unuse(type, frontswap, &pages_to_unuse); |
| if (retval) |
| goto out; |
| |
| prev_mm = &init_mm; |
| mmget(prev_mm); |
| |
| spin_lock(&mmlist_lock); |
| p = &init_mm.mmlist; |
| while (READ_ONCE(si->inuse_pages) && |
| !signal_pending(current) && |
| (p = p->next) != &init_mm.mmlist) { |
| |
| mm = list_entry(p, struct mm_struct, mmlist); |
| if (!mmget_not_zero(mm)) |
| continue; |
| spin_unlock(&mmlist_lock); |
| mmput(prev_mm); |
| prev_mm = mm; |
| retval = unuse_mm(mm, type, frontswap, &pages_to_unuse); |
| |
| if (retval) { |
| mmput(prev_mm); |
| goto out; |
| } |
| |
| /* |
| * Make sure that we aren't completely killing |
| * interactive performance. |
| */ |
| cond_resched(); |
| spin_lock(&mmlist_lock); |
| } |
| spin_unlock(&mmlist_lock); |
| |
| mmput(prev_mm); |
| |
| i = 0; |
| while (READ_ONCE(si->inuse_pages) && |
| !signal_pending(current) && |
| (i = find_next_to_unuse(si, i, frontswap)) != 0) { |
| |
| entry = swp_entry(type, i); |
| page = find_get_page(swap_address_space(entry), i); |
| if (!page) |
| continue; |
| |
| /* |
| * It is conceivable that a racing task removed this page from |
| * swap cache just before we acquired the page lock. The page |
| * might even be back in swap cache on another swap area. But |
| * that is okay, try_to_free_swap() only removes stale pages. |
| */ |
| lock_page(page); |
| wait_on_page_writeback(page); |
| try_to_free_swap(page); |
| unlock_page(page); |
| put_page(page); |
| |
| /* |
| * For frontswap, we just need to unuse pages_to_unuse, if |
| * it was specified. Need not check frontswap again here as |
| * we already zeroed out pages_to_unuse if not frontswap. |
| */ |
| if (pages_to_unuse && --pages_to_unuse == 0) |
| goto out; |
| } |
| |
| /* |
| * Lets check again to see if there are still swap entries in the map. |
| * If yes, we would need to do retry the unuse logic again. |
| * Under global memory pressure, swap entries can be reinserted back |
| * into process space after the mmlist loop above passes over them. |
| * |
| * Limit the number of retries? No: when mmget_not_zero() above fails, |
| * that mm is likely to be freeing swap from exit_mmap(), which proceeds |
| * at its own independent pace; and even shmem_writepage() could have |
| * been preempted after get_swap_page(), temporarily hiding that swap. |
| * It's easy and robust (though cpu-intensive) just to keep retrying. |
| */ |
| if (READ_ONCE(si->inuse_pages)) { |
| if (!signal_pending(current)) |
| goto retry; |
| retval = -EINTR; |
| } |
| out: |
| return (retval == FRONTSWAP_PAGES_UNUSED) ? 0 : retval; |
| } |
| |
| /* |
| * After a successful try_to_unuse, if no swap is now in use, we know |
| * we can empty the mmlist. swap_lock must be held on entry and exit. |
| * Note that mmlist_lock nests inside swap_lock, and an mm must be |
| * added to the mmlist just after page_duplicate - before would be racy. |
| */ |
| static void drain_mmlist(void) |
| { |
| struct list_head *p, *next; |
| unsigned int type; |
| |
| for (type = 0; type < nr_swapfiles; type++) |
| if (swap_info[type]->inuse_pages) |
| return; |
| spin_lock(&mmlist_lock); |
| list_for_each_safe(p, next, &init_mm.mmlist) |
| list_del_init(p); |
| spin_unlock(&mmlist_lock); |
| } |
| |
| /* |
| * Use this swapdev's extent info to locate the (PAGE_SIZE) block which |
| * corresponds to page offset for the specified swap entry. |
| * Note that the type of this function is sector_t, but it returns page offset |
| * into the bdev, not sector offset. |
| */ |
| static sector_t map_swap_entry(swp_entry_t entry, struct block_device **bdev) |
| { |
| struct swap_info_struct *sis; |
| struct swap_extent *se; |
| pgoff_t offset; |
| |
| sis = swp_swap_info(entry); |
| *bdev = sis->bdev; |
| |
| offset = swp_offset(entry); |
| se = offset_to_swap_extent(sis, offset); |
| return se->start_block + (offset - se->start_page); |
| } |
| |
| /* |
| * Returns the page offset into bdev for the specified page's swap entry. |
| */ |
| sector_t map_swap_page(struct page *page, struct block_device **bdev) |
| { |
| swp_entry_t entry; |
| entry.val = page_private(page); |
| return map_swap_entry(entry, bdev); |
| } |
| |
| /* |
| * Free all of a swapdev's extent information |
| */ |
| static void destroy_swap_extents(struct swap_info_struct *sis) |
| { |
| while (!RB_EMPTY_ROOT(&sis->swap_extent_root)) { |
| struct rb_node *rb = sis->swap_extent_root.rb_node; |
| struct swap_extent *se = rb_entry(rb, struct swap_extent, rb_node); |
| |
| rb_erase(rb, &sis->swap_extent_root); |
| kfree(se); |
| } |
| |
| if (sis->flags & SWP_ACTIVATED) { |
| struct file *swap_file = sis->swap_file; |
| struct address_space *mapping = swap_file->f_mapping; |
| |
| sis->flags &= ~SWP_ACTIVATED; |
| if (mapping->a_ops->swap_deactivate) |
| mapping->a_ops->swap_deactivate(swap_file); |
| } |
| } |
| |
| /* |
| * Add a block range (and the corresponding page range) into this swapdev's |
| * extent tree. |
| * |
| * This function rather assumes that it is called in ascending page order. |
| */ |
| int |
| add_swap_extent(struct swap_info_struct *sis, unsigned long start_page, |
| unsigned long nr_pages, sector_t start_block) |
| { |
| struct rb_node **link = &sis->swap_extent_root.rb_node, *parent = NULL; |
| struct swap_extent *se; |
| struct swap_extent *new_se; |
| |
| /* |
| * place the new node at the right most since the |
| * function is called in ascending page order. |
| */ |
| while (*link) { |
| parent = *link; |
| link = &parent->rb_right; |
| } |
| |
| if (parent) { |
| se = rb_entry(parent, struct swap_extent, rb_node); |
| BUG_ON(se->start_page + se->nr_pages != start_page); |
| if (se->start_block + se->nr_pages == start_block) { |
| /* Merge it */ |
| se->nr_pages += nr_pages; |
| return 0; |
| } |
| } |
| |
| /* No merge, insert a new extent. */ |
| new_se = kmalloc(sizeof(*se), GFP_KERNEL); |
| if (new_se == NULL) |
| return -ENOMEM; |
| new_se->start_page = start_page; |
| new_se->nr_pages = nr_pages; |
| new_se->start_block = start_block; |
| |
| rb_link_node(&new_se->rb_node, parent, link); |
| rb_insert_color(&new_se->rb_node, &sis->swap_extent_root); |
| return 1; |
| } |
| EXPORT_SYMBOL_GPL(add_swap_extent); |
| |
| /* |
| * A `swap extent' is a simple thing which maps a contiguous range of pages |
| * onto a contiguous range of disk blocks. An ordered list of swap extents |
| * is built at swapon time and is then used at swap_writepage/swap_readpage |
| * time for locating where on disk a page belongs. |
| * |
| * If the swapfile is an S_ISBLK block device, a single extent is installed. |
| * This is done so that the main operating code can treat S_ISBLK and S_ISREG |
| * swap files identically. |
| * |
| * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap |
| * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK |
| * swapfiles are handled *identically* after swapon time. |
| * |
| * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks |
| * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If |
| * some stray blocks are found which do not fall within the PAGE_SIZE alignment |
| * requirements, they are simply tossed out - we will never use those blocks |
| * for swapping. |
| * |
| * For all swap devices we set S_SWAPFILE across the life of the swapon. This |
| * prevents users from writing to the swap device, which will corrupt memory. |
| * |
| * The amount of disk space which a single swap extent represents varies. |
| * Typically it is in the 1-4 megabyte range. So we can have hundreds of |
| * extents in the list. To avoid much list walking, we cache the previous |
| * search location in `curr_swap_extent', and start new searches from there. |
| * This is extremely effective. The average number of iterations in |
| * map_swap_page() has been measured at about 0.3 per page. - akpm. |
| */ |
| static int setup_swap_extents(struct swap_info_struct *sis, sector_t *span) |
| { |
| struct file *swap_file = sis->swap_file; |
| struct address_space *mapping = swap_file->f_mapping; |
| struct inode *inode = mapping->host; |
| int ret; |
| |
| if (S_ISBLK(inode->i_mode)) { |
| ret = add_swap_extent(sis, 0, sis->max, 0); |
| *span = sis->pages; |
| return ret; |
| } |
| |
| if (mapping->a_ops->swap_activate) { |
| ret = mapping->a_ops->swap_activate(sis, swap_file, span); |
| if (ret >= 0) |
| sis->flags |= SWP_ACTIVATED; |
| if (!ret) { |
| sis->flags |= SWP_FS; |
| ret = add_swap_extent(sis, 0, sis->max, 0); |
| *span = sis->pages; |
| } |
| return ret; |
| } |
| |
| return generic_swapfile_activate(sis, swap_file, span); |
| } |
| |
| static int swap_node(struct swap_info_struct *p) |
| { |
| struct block_device *bdev; |
| |
| if (p->bdev) |
| bdev = p->bdev; |
| else |
| bdev = p->swap_file->f_inode->i_sb->s_bdev; |
| |
| return bdev ? bdev->bd_disk->node_id : NUMA_NO_NODE; |
| } |
| |
| static void setup_swap_info(struct swap_info_struct *p, int prio, |
| unsigned char *swap_map, |
| struct swap_cluster_info *cluster_info) |
| { |
| int i; |
| |
| if (prio >= 0) |
| p->prio = prio; |
| else |
| p->prio = --least_priority; |
| /* |
| * the plist prio is negated because plist ordering is |
| * low-to-high, while swap ordering is high-to-low |
| */ |
| p->list.prio = -p->prio; |
| for_each_node(i) { |
| if (p->prio >= 0) |
| p->avail_lists[i].prio = -p->prio; |
| else { |
| if (swap_node(p) == i) |
| p->avail_lists[i].prio = 1; |
| else |
| p->avail_lists[i].prio = -p->prio; |
| } |
| } |
| p->swap_map = swap_map; |
| p->cluster_info = cluster_info; |
| } |
| |
| static void _enable_swap_info(struct swap_info_struct *p) |
| { |
| p->flags |= SWP_WRITEOK | SWP_VALID; |
| atomic_long_add(p->pages, &nr_swap_pages); |
| total_swap_pages += p->pages; |
| |
| assert_spin_locked(&swap_lock); |
| /* |
| * both lists are plists, and thus priority ordered. |
| * swap_active_head needs to be priority ordered for swapoff(), |
| * which on removal of any swap_info_struct with an auto-assigned |
| * (i.e. negative) priority increments the auto-assigned priority |
| * of any lower-priority swap_info_structs. |
| * swap_avail_head needs to be priority ordered for get_swap_page(), |
| * which allocates swap pages from the highest available priority |
| * swap_info_struct. |
| */ |
| plist_add(&p->list, &swap_active_head); |
| add_to_avail_list(p); |
| } |
| |
| static void enable_swap_info(struct swap_info_struct *p, int prio, |
| unsigned char *swap_map, |
| struct swap_cluster_info *cluster_info, |
| unsigned long *frontswap_map) |
| { |
| frontswap_init(p->type, frontswap_map); |
| spin_lock(&swap_lock); |
| spin_lock(&p->lock); |
| setup_swap_info(p, prio, swap_map, cluster_info); |
| spin_unlock(&p->lock); |
| spin_unlock(&swap_lock); |
| /* |
| * Guarantee swap_map, cluster_info, etc. fields are valid |
| * between get/put_swap_device() if SWP_VALID bit is set |
| */ |
| synchronize_rcu(); |
| spin_lock(&swap_lock); |
| spin_lock(&p->lock); |
| _enable_swap_info(p); |
| spin_unlock(&p->lock); |
| spin_unlock(&swap_lock); |
| } |
| |
| static void reinsert_swap_info(struct swap_info_struct *p) |
| { |
| spin_lock(&swap_lock); |
| spin_lock(&p->lock); |
| setup_swap_info(p, p->prio, p->swap_map, p->cluster_info); |
| _enable_swap_info(p); |
| spin_unlock(&p->lock); |
| spin_unlock(&swap_lock); |
| } |
| |
| bool has_usable_swap(void) |
| { |
| bool ret = true; |
| |
| spin_lock(&swap_lock); |
| if (plist_head_empty(&swap_active_head)) |
| ret = false; |
| spin_unlock(&swap_lock); |
| return ret; |
| } |
| |
| SYSCALL_DEFINE1(swapoff, const char __user *, specialfile) |
| { |
| struct swap_info_struct *p = NULL; |
| unsigned char *swap_map; |
| struct swap_cluster_info *cluster_info; |
| unsigned long *frontswap_map; |
| struct file *swap_file, *victim; |
| struct address_space *mapping; |
| struct inode *inode; |
| struct filename *pathname; |
| int err, found = 0; |
| unsigned int old_block_size; |
| |
| if (!capable(CAP_SYS_ADMIN)) |
| return -EPERM; |
| |
| BUG_ON(!current->mm); |
| |
| pathname = getname(specialfile); |
| if (IS_ERR(pathname)) |
| return PTR_ERR(pathname); |
| |
| victim = file_open_name(pathname, O_RDWR|O_LARGEFILE, 0); |
| err = PTR_ERR(victim); |
| if (IS_ERR(victim)) |
| goto out; |
| |
| mapping = victim->f_mapping; |
| spin_lock(&swap_lock); |
| plist_for_each_entry(p, &swap_active_head, list) { |
| if (p->flags & SWP_WRITEOK) { |
| if (p->swap_file->f_mapping == mapping) { |
| found = 1; |
| break; |
| } |
| } |
| } |
| if (!found) { |
| err = -EINVAL; |
| spin_unlock(&swap_lock); |
| goto out_dput; |
| } |
| if (!security_vm_enough_memory_mm(current->mm, p->pages)) |
| vm_unacct_memory(p->pages); |
| else { |
| err = -ENOMEM; |
| spin_unlock(&swap_lock); |
| goto out_dput; |
| } |
| del_from_avail_list(p); |
| spin_lock(&p->lock); |
| if (p->prio < 0) { |
| struct swap_info_struct *si = p; |
| int nid; |
| |
| plist_for_each_entry_continue(si, &swap_active_head, list) { |
| si->prio++; |
| si->list.prio--; |
| for_each_node(nid) { |
| if (si->avail_lists[nid].prio != 1) |
| si->avail_lists[nid].prio--; |
| } |
| } |
| least_priority++; |
| } |
| plist_del(&p->list, &swap_active_head); |
| atomic_long_sub(p->pages, &nr_swap_pages); |
| total_swap_pages -= p->pages; |
| p->flags &= ~SWP_WRITEOK; |
| spin_unlock(&p->lock); |
| spin_unlock(&swap_lock); |
| |
| disable_swap_slots_cache_lock(); |
| |
| set_current_oom_origin(); |
| err = try_to_unuse(p->type, false, 0); /* force unuse all pages */ |
| clear_current_oom_origin(); |
| |
| if (err) { |
| /* re-insert swap space back into swap_list */ |
| reinsert_swap_info(p); |
| reenable_swap_slots_cache_unlock(); |
| goto out_dput; |
| } |
| |
| reenable_swap_slots_cache_unlock(); |
| |
| spin_lock(&swap_lock); |
| spin_lock(&p->lock); |
| p->flags &= ~SWP_VALID; /* mark swap device as invalid */ |
| spin_unlock(&p->lock); |
| spin_unlock(&swap_lock); |
| /* |
| * wait for swap operations protected by get/put_swap_device() |
| * to complete |
| */ |
| synchronize_rcu(); |
| |
| flush_work(&p->discard_work); |
| |
| destroy_swap_extents(p); |
| if (p->flags & SWP_CONTINUED) |
| free_swap_count_continuations(p); |
| |
| if (!p->bdev || !blk_queue_nonrot(bdev_get_queue(p->bdev))) |
| atomic_dec(&nr_rotate_swap); |
| |
| mutex_lock(&swapon_mutex); |
| spin_lock(&swap_lock); |
| spin_lock(&p->lock); |
| drain_mmlist(); |
| |
| /* wait for anyone still in scan_swap_map */ |
| p->highest_bit = 0; /* cuts scans short */ |
| while (p->flags >= SWP_SCANNING) { |
| spin_unlock(&p->lock); |
| spin_unlock(&swap_lock); |
| schedule_timeout_uninterruptible(1); |
| spin_lock(&swap_lock); |
| spin_lock(&p->lock); |
| } |
| |
| swap_file = p->swap_file; |
| old_block_size = p->old_block_size; |
| p->swap_file = NULL; |
| p->max = 0; |
| swap_map = p->swap_map; |
| p->swap_map = NULL; |
| cluster_info = p->cluster_info; |
| p->cluster_info = NULL; |
| frontswap_map = frontswap_map_get(p); |
| spin_unlock(&p->lock); |
| spin_unlock(&swap_lock); |
| frontswap_invalidate_area(p->type); |
| frontswap_map_set(p, NULL); |
| mutex_unlock(&swapon_mutex); |
| free_percpu(p->percpu_cluster); |
| p->percpu_cluster = NULL; |
| free_percpu(p->cluster_next_cpu); |
| p->cluster_next_cpu = NULL; |
| vfree(swap_map); |
| kvfree(cluster_info); |
| kvfree(frontswap_map); |
| /* Destroy swap account information */ |
| swap_cgroup_swapoff(p->type); |
| exit_swap_address_space(p->type); |
| |
| inode = mapping->host; |
| if (S_ISBLK(inode->i_mode)) { |
| struct block_device *bdev = I_BDEV(inode); |
| |
| set_blocksize(bdev, old_block_size); |
| blkdev_put(bdev, FMODE_READ | FMODE_WRITE | FMODE_EXCL); |
| } |
| |
| inode_lock(inode); |
| inode->i_flags &= ~S_SWAPFILE; |
| inode_unlock(inode); |
| filp_close(swap_file, NULL); |
| |
| /* |
| * Clear the SWP_USED flag after all resources are freed so that swapon |
| * can reuse this swap_info in alloc_swap_info() safely. It is ok to |
| * not hold p->lock after we cleared its SWP_WRITEOK. |
| */ |
| spin_lock(&swap_lock); |
| p->flags = 0; |
| spin_unlock(&swap_lock); |
| |
| err = 0; |
| atomic_inc(&proc_poll_event); |
| wake_up_interruptible(&proc_poll_wait); |
| |
| out_dput: |
| filp_close(victim, NULL); |
| out: |
| putname(pathname); |
| return err; |
| } |
| |
| #ifdef CONFIG_PROC_FS |
| static __poll_t swaps_poll(struct file *file, poll_table *wait) |
| { |
| struct seq_file *seq = file->private_data; |
| |
| poll_wait(file, &proc_poll_wait, wait); |
| |
| if (seq->poll_event != atomic_read(&proc_poll_event)) { |
| seq->poll_event = atomic_read(&proc_poll_event); |
| return EPOLLIN | EPOLLRDNORM | EPOLLERR | EPOLLPRI; |
| } |
| |
| return EPOLLIN | EPOLLRDNORM; |
| } |
| |
| /* iterator */ |
| static void *swap_start(struct seq_file *swap, loff_t *pos) |
| { |
| struct swap_info_struct *si; |
| int type; |
| loff_t l = *pos; |
| |
| mutex_lock(&swapon_mutex); |
| |
| if (!l) |
| return SEQ_START_TOKEN; |
| |
| for (type = 0; (si = swap_type_to_swap_info(type)); type++) { |
| if (!(si->flags & SWP_USED) || !si->swap_map) |
| continue; |
| if (!--l) |
| return si; |
| } |
| |
| return NULL; |
| } |
| |
| static void *swap_next(struct seq_file *swap, void *v, loff_t *pos) |
| { |
| struct swap_info_struct *si = v; |
| int type; |
| |
| if (v == SEQ_START_TOKEN) |
| type = 0; |
| else |
| type = si->type + 1; |
| |
| ++(*pos); |
| for (; (si = swap_type_to_swap_info(type)); type++) { |
| if (!(si->flags & SWP_USED) || !si->swap_map) |
| continue; |
| return si; |
| } |
| |
| return NULL; |
| } |
| |
| static void swap_stop(struct seq_file *swap, void *v) |
| { |
| mutex_unlock(&swapon_mutex); |
| } |
| |
| static int swap_show(struct seq_file *swap, void *v) |
| { |
| struct swap_info_struct *si = v; |
| struct file *file; |
| int len; |
| unsigned int bytes, inuse; |
| |
| if (si == SEQ_START_TOKEN) { |
| seq_puts(swap,"Filename\t\t\t\tType\t\tSize\t\tUsed\t\tPriority\n"); |
| return 0; |
| } |
| |
| bytes = si->pages << (PAGE_SHIFT - 10); |
| inuse = si->inuse_pages << (PAGE_SHIFT - 10); |
| |
| file = si->swap_file; |
| len = seq_file_path(swap, file, " \t\n\\"); |
| seq_printf(swap, "%*s%s\t%u\t%s%u\t%s%d\n", |
| len < 40 ? 40 - len : 1, " ", |
| S_ISBLK(file_inode(file)->i_mode) ? |
| "partition" : "file\t", |
| bytes, bytes < 10000000 ? "\t" : "", |
| inuse, inuse < 10000000 ? "\t" : "", |
| si->prio); |
| return 0; |
| } |
| |
| static const struct seq_operations swaps_op = { |
| .start = swap_start, |
| .next = swap_next, |
| .stop = swap_stop, |
| .show = swap_show |
| }; |
| |
| static int swaps_open(struct inode *inode, struct file *file) |
| { |
| struct seq_file *seq; |
| int ret; |
| |
| ret = seq_open(file, &swaps_op); |
| if (ret) |
| return ret; |
| |
| seq = file->private_data; |
| seq->poll_event = atomic_read(&proc_poll_event); |
| return 0; |
| } |
| |
| static const struct proc_ops swaps_proc_ops = { |
| .proc_flags = PROC_ENTRY_PERMANENT, |
| .proc_open = swaps_open, |
| .proc_read = seq_read, |
| .proc_lseek = seq_lseek, |
| .proc_release = seq_release, |
| .proc_poll = swaps_poll, |
| }; |
| |
| static int __init procswaps_init(void) |
| { |
| proc_create("swaps", 0, NULL, &swaps_proc_ops); |
| return 0; |
| } |
| __initcall(procswaps_init); |
| #endif /* CONFIG_PROC_FS */ |
| |
| #ifdef MAX_SWAPFILES_CHECK |
| static int __init max_swapfiles_check(void) |
| { |
| MAX_SWAPFILES_CHECK(); |
| return 0; |
| } |
| late_initcall(max_swapfiles_check); |
| #endif |
| |
| static struct swap_info_struct *alloc_swap_info(void) |
| { |
| struct swap_info_struct *p; |
| unsigned int type; |
| int i; |
| |
| p = kvzalloc(struct_size(p, avail_lists, nr_node_ids), GFP_KERNEL); |
| if (!p) |
| return ERR_PTR(-ENOMEM); |
| |
| spin_lock(&swap_lock); |
| for (type = 0; type < nr_swapfiles; type++) { |
| if (!(swap_info[type]->flags & SWP_USED)) |
| break; |
| } |
| if (type >= MAX_SWAPFILES) { |
| spin_unlock(&swap_lock); |
| kvfree(p); |
| return ERR_PTR(-EPERM); |
| } |
| if (type >= nr_swapfiles) { |
| p->type = type; |
| WRITE_ONCE(swap_info[type], p); |
| /* |
| * Write swap_info[type] before nr_swapfiles, in case a |
| * racing procfs swap_start() or swap_next() is reading them. |
| * (We never shrink nr_swapfiles, we never free this entry.) |
| */ |
| smp_wmb(); |
| WRITE_ONCE(nr_swapfiles, nr_swapfiles + 1); |
| } else { |
| kvfree(p); |
| p = swap_info[type]; |
| /* |
| * Do not memset this entry: a racing procfs swap_next() |
| * would be relying on p->type to remain valid. |
| */ |
| } |
| p->swap_extent_root = RB_ROOT; |
| plist_node_init(&p->list, 0); |
| for_each_node(i) |
| plist_node_init(&p->avail_lists[i], 0); |
| p->flags = SWP_USED; |
| spin_unlock(&swap_lock); |
| spin_lock_init(&p->lock); |
| spin_lock_init(&p->cont_lock); |
| |
| return p; |
| } |
| |
| static int claim_swapfile(struct swap_info_struct *p, struct inode *inode) |
| { |
| int error; |
| |
| if (S_ISBLK(inode->i_mode)) { |
| p->bdev = bdgrab(I_BDEV(inode)); |
| error = blkdev_get(p->bdev, |
| FMODE_READ | FMODE_WRITE | FMODE_EXCL, p); |
| if (error < 0) { |
| p->bdev = NULL; |
| return error; |
| } |
| p->old_block_size = block_size(p->bdev); |
| error = set_blocksize(p->bdev, PAGE_SIZE); |
| if (error < 0) |
| return error; |
| /* |
| * Zoned block devices contain zones that have a sequential |
| * write only restriction. Hence zoned block devices are not |
| * suitable for swapping. Disallow them here. |
| */ |
| if (blk_queue_is_zoned(p->bdev->bd_queue)) |
| return -EINVAL; |
| p->flags |= SWP_BLKDEV; |
| } else if (S_ISREG(inode->i_mode)) { |
| p->bdev = inode->i_sb->s_bdev; |
| } |
| |
| return 0; |
| } |
| |
| |
| /* |
| * Find out how many pages are allowed for a single swap device. There |
| * are two limiting factors: |
| * 1) the number of bits for the swap offset in the swp_entry_t type, and |
| * 2) the number of bits in the swap pte, as defined by the different |
| * architectures. |
| * |
| * In order to find the largest possible bit mask, a swap entry with |
| * swap type 0 and swap offset ~0UL is created, encoded to a swap pte, |
| * decoded to a swp_entry_t again, and finally the swap offset is |
| * extracted. |
| * |
| * This will mask all the bits from the initial ~0UL mask that can't |
| * be encoded in either the swp_entry_t or the architecture definition |
| * of a swap pte. |
| */ |
| unsigned long generic_max_swapfile_size(void) |
| { |
| return swp_offset(pte_to_swp_entry( |
| swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1; |
| } |
| |
| /* Can be overridden by an architecture for additional checks. */ |
| __weak unsigned long max_swapfile_size(void) |
| { |
| return generic_max_swapfile_size(); |
| } |
| |
| static unsigned long read_swap_header(struct swap_info_struct *p, |
| union swap_header *swap_header, |
| struct inode *inode) |
| { |
| int i; |
| unsigned long maxpages; |
| unsigned long swapfilepages; |
| unsigned long last_page; |
| |
| if (memcmp("SWAPSPACE2", swap_header->magic.magic, 10)) { |
| pr_err("Unable to find swap-space signature\n"); |
| return 0; |
| } |
| |
| /* swap partition endianess hack... */ |
| if (swab32(swap_header->info.version) == 1) { |
| swab32s(&swap_header->info.version); |
| swab32s(&swap_header->info.last_page); |
| swab32s(&swap_header->info.nr_badpages); |
| if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
| return 0; |
| for (i = 0; i < swap_header->info.nr_badpages; i++) |
| swab32s(&swap_header->info.badpages[i]); |
| } |
| /* Check the swap header's sub-version */ |
| if (swap_header->info.version != 1) { |
| pr_warn("Unable to handle swap header version %d\n", |
| swap_header->info.version); |
| return 0; |
| } |
| |
| p->lowest_bit = 1; |
| p->cluster_next = 1; |
| p->cluster_nr = 0; |
| |
| maxpages = max_swapfile_size(); |
| last_page = swap_header->info.last_page; |
| if (!last_page) { |
| pr_warn("Empty swap-file\n"); |
| return 0; |
| } |
| if (last_page > maxpages) { |
| pr_warn("Truncating oversized swap area, only using %luk out of %luk\n", |
| maxpages << (PAGE_SHIFT - 10), |
| last_page << (PAGE_SHIFT - 10)); |
| } |
| if (maxpages > last_page) { |
| maxpages = last_page + 1; |
| /* p->max is an unsigned int: don't overflow it */ |
| if ((unsigned int)maxpages == 0) |
| maxpages = UINT_MAX; |
| } |
| p->highest_bit = maxpages - 1; |
| |
| if (!maxpages) |
| return 0; |
| swapfilepages = i_size_read(inode) >> PAGE_SHIFT; |
| if (swapfilepages && maxpages > swapfilepages) { |
| pr_warn("Swap area shorter than signature indicates\n"); |
| return 0; |
| } |
| if (swap_header->info.nr_badpages && S_ISREG(inode->i_mode)) |
| return 0; |
| if (swap_header->info.nr_badpages > MAX_SWAP_BADPAGES) |
| return 0; |
| |
| return maxpages; |
| } |
| |
| #define SWAP_CLUSTER_INFO_COLS \ |
| DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info)) |
| #define SWAP_CLUSTER_SPACE_COLS \ |
| DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER) |
| #define SWAP_CLUSTER_COLS \ |
| max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS) |
| |
| static int setup_swap_map_and_extents(struct swap_info_struct *p, |
| union swap_header *swap_header, |
| unsigned char *swap_map, |
| struct swap_cluster_info *cluster_info, |
| unsigned long maxpages, |
| sector_t *span) |
| { |
| unsigned int j, k; |
| unsigned int nr_good_pages; |
| int nr_extents; |
| unsigned long nr_clusters = DIV_ROUND_UP(maxpages, SWAPFILE_CLUSTER); |
| unsigned long col = p->cluster_next / SWAPFILE_CLUSTER % SWAP_CLUSTER_COLS; |
| unsigned long i, idx; |
| |
| nr_good_pages = maxpages - 1; /* omit header page */ |
| |
| cluster_list_init(&p->free_clusters); |
| cluster_list_init(&p->discard_clusters); |
| |
| for (i = 0; i < swap_header->info.nr_badpages; i++) { |
| unsigned int page_nr = swap_header->info.badpages[i]; |
| if (page_nr == 0 || page_nr > swap_header->info.last_page) |
| return -EINVAL; |
| if (page_nr < maxpages) { |
| swap_map[page_nr] = SWAP_MAP_BAD; |
| nr_good_pages--; |
| /* |
| * Haven't marked the cluster free yet, no list |
| * operation involved |
| */ |
| inc_cluster_info_page(p, cluster_info, page_nr); |
| } |
| } |
| |
| /* Haven't marked the cluster free yet, no list operation involved */ |
| for (i = maxpages; i < round_up(maxpages, SWAPFILE_CLUSTER); i++) |
| inc_cluster_info_page(p, cluster_info, i); |
| |
| if (nr_good_pages) { |
| swap_map[0] = SWAP_MAP_BAD; |
| /* |
| * Not mark the cluster free yet, no list |
| * operation involved |
| */ |
| inc_cluster_info_page(p, cluster_info, 0); |
| p->max = maxpages; |
| p->pages = nr_good_pages; |
| nr_extents = setup_swap_extents(p, span); |
| if (nr_extents < 0) |
| return nr_extents; |
| nr_good_pages = p->pages; |
| } |
| if (!nr_good_pages) { |
| pr_warn("Empty swap-file\n"); |
| return -EINVAL; |
| } |
| |
| if (!cluster_info) |
| return nr_extents; |
| |
| |
| /* |
| * Reduce false cache line sharing between cluster_info and |
| * sharing same address space. |
| */ |
| for (k = 0; k < SWAP_CLUSTER_COLS; k++) { |
| j = (k + col) % SWAP_CLUSTER_COLS; |
| for (i = 0; i < DIV_ROUND_UP(nr_clusters, SWAP_CLUSTER_COLS); i++) { |
| idx = i * SWAP_CLUSTER_COLS + j; |
| if (idx >= nr_clusters) |
| continue; |
| if (cluster_count(&cluster_info[idx])) |
| continue; |
| cluster_set_flag(&cluster_info[idx], CLUSTER_FLAG_FREE); |
| cluster_list_add_tail(&p->free_clusters, cluster_info, |
| idx); |
| } |
| } |
| return nr_extents; |
|