1 // SPDX-License-Identifier: GPL-2.0-only
5 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
6 * Swap reorganised 29.12.95, Stephen Tweedie
10 #include <linux/sched/mm.h>
11 #include <linux/sched/task.h>
12 #include <linux/hugetlb.h>
13 #include <linux/mman.h>
14 #include <linux/slab.h>
15 #include <linux/kernel_stat.h>
16 #include <linux/swap.h>
17 #include <linux/vmalloc.h>
18 #include <linux/pagemap.h>
19 #include <linux/namei.h>
20 #include <linux/shmem_fs.h>
21 #include <linux/blkdev.h>
22 #include <linux/random.h>
23 #include <linux/writeback.h>
24 #include <linux/proc_fs.h>
25 #include <linux/seq_file.h>
26 #include <linux/init.h>
27 #include <linux/ksm.h>
28 #include <linux/rmap.h>
29 #include <linux/security.h>
30 #include <linux/backing-dev.h>
31 #include <linux/mutex.h>
32 #include <linux/capability.h>
33 #include <linux/syscalls.h>
34 #include <linux/memcontrol.h>
35 #include <linux/poll.h>
36 #include <linux/oom.h>
37 #include <linux/frontswap.h>
38 #include <linux/swapfile.h>
39 #include <linux/export.h>
40 #include <linux/swap_slots.h>
41 #include <linux/sort.h>
43 #include <asm/pgtable.h>
44 #include <asm/tlbflush.h>
45 #include <linux/swapops.h>
46 #include <linux/swap_cgroup.h>
48 static bool swap_count_continued(struct swap_info_struct
*, pgoff_t
,
50 static void free_swap_count_continuations(struct swap_info_struct
*);
51 static sector_t
map_swap_entry(swp_entry_t
, struct block_device
**);
53 DEFINE_SPINLOCK(swap_lock
);
54 static unsigned int nr_swapfiles
;
55 atomic_long_t nr_swap_pages
;
57 * Some modules use swappable objects and may try to swap them out under
58 * memory pressure (via the shrinker). Before doing so, they may wish to
59 * check to see if any swap space is available.
61 EXPORT_SYMBOL_GPL(nr_swap_pages
);
62 /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */
63 long total_swap_pages
;
64 static int least_priority
= -1;
66 static const char Bad_file
[] = "Bad swap file entry ";
67 static const char Unused_file
[] = "Unused swap file entry ";
68 static const char Bad_offset
[] = "Bad swap offset entry ";
69 static const char Unused_offset
[] = "Unused swap offset entry ";
72 * all active swap_info_structs
73 * protected with swap_lock, and ordered by priority.
75 PLIST_HEAD(swap_active_head
);
78 * all available (active, not full) swap_info_structs
79 * protected with swap_avail_lock, ordered by priority.
80 * This is used by get_swap_page() instead of swap_active_head
81 * because swap_active_head includes all swap_info_structs,
82 * but get_swap_page() doesn't need to look at full ones.
83 * This uses its own lock instead of swap_lock because when a
84 * swap_info_struct changes between not-full/full, it needs to
85 * add/remove itself to/from this list, but the swap_info_struct->lock
86 * is held and the locking order requires swap_lock to be taken
87 * before any swap_info_struct->lock.
89 static struct plist_head
*swap_avail_heads
;
90 static DEFINE_SPINLOCK(swap_avail_lock
);
92 struct swap_info_struct
*swap_info
[MAX_SWAPFILES
];
94 static DEFINE_MUTEX(swapon_mutex
);
96 static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait
);
97 /* Activity counter to indicate that a swapon or swapoff has occurred */
98 static atomic_t proc_poll_event
= ATOMIC_INIT(0);
100 atomic_t nr_rotate_swap
= ATOMIC_INIT(0);
102 static struct swap_info_struct
*swap_type_to_swap_info(int type
)
104 if (type
>= READ_ONCE(nr_swapfiles
))
107 smp_rmb(); /* Pairs with smp_wmb in alloc_swap_info. */
108 return READ_ONCE(swap_info
[type
]);
111 static inline unsigned char swap_count(unsigned char ent
)
113 return ent
& ~SWAP_HAS_CACHE
; /* may include COUNT_CONTINUED flag */
116 /* Reclaim the swap entry anyway if possible */
117 #define TTRS_ANYWAY 0x1
119 * Reclaim the swap entry if there are no more mappings of the
122 #define TTRS_UNMAPPED 0x2
123 /* Reclaim the swap entry if swap is getting full*/
124 #define TTRS_FULL 0x4
126 /* returns 1 if swap entry is freed */
127 static int __try_to_reclaim_swap(struct swap_info_struct
*si
,
128 unsigned long offset
, unsigned long flags
)
130 swp_entry_t entry
= swp_entry(si
->type
, offset
);
134 page
= find_get_page(swap_address_space(entry
), offset
);
138 * When this function is called from scan_swap_map_slots() and it's
139 * called by vmscan.c at reclaiming pages. So, we hold a lock on a page,
140 * here. We have to use trylock for avoiding deadlock. This is a special
141 * case and you should use try_to_free_swap() with explicit lock_page()
142 * in usual operations.
144 if (trylock_page(page
)) {
145 if ((flags
& TTRS_ANYWAY
) ||
146 ((flags
& TTRS_UNMAPPED
) && !page_mapped(page
)) ||
147 ((flags
& TTRS_FULL
) && mem_cgroup_swap_full(page
)))
148 ret
= try_to_free_swap(page
);
155 static inline struct swap_extent
*first_se(struct swap_info_struct
*sis
)
157 struct rb_node
*rb
= rb_first(&sis
->swap_extent_root
);
158 return rb_entry(rb
, struct swap_extent
, rb_node
);
161 static inline struct swap_extent
*next_se(struct swap_extent
*se
)
163 struct rb_node
*rb
= rb_next(&se
->rb_node
);
164 return rb
? rb_entry(rb
, struct swap_extent
, rb_node
) : NULL
;
168 * swapon tell device that all the old swap contents can be discarded,
169 * to allow the swap device to optimize its wear-levelling.
171 static int discard_swap(struct swap_info_struct
*si
)
173 struct swap_extent
*se
;
174 sector_t start_block
;
178 /* Do not discard the swap header page! */
180 start_block
= (se
->start_block
+ 1) << (PAGE_SHIFT
- 9);
181 nr_blocks
= ((sector_t
)se
->nr_pages
- 1) << (PAGE_SHIFT
- 9);
183 err
= blkdev_issue_discard(si
->bdev
, start_block
,
184 nr_blocks
, GFP_KERNEL
, 0);
190 for (se
= next_se(se
); se
; se
= next_se(se
)) {
191 start_block
= se
->start_block
<< (PAGE_SHIFT
- 9);
192 nr_blocks
= (sector_t
)se
->nr_pages
<< (PAGE_SHIFT
- 9);
194 err
= blkdev_issue_discard(si
->bdev
, start_block
,
195 nr_blocks
, GFP_KERNEL
, 0);
201 return err
; /* That will often be -EOPNOTSUPP */
204 static struct swap_extent
*
205 offset_to_swap_extent(struct swap_info_struct
*sis
, unsigned long offset
)
207 struct swap_extent
*se
;
210 rb
= sis
->swap_extent_root
.rb_node
;
212 se
= rb_entry(rb
, struct swap_extent
, rb_node
);
213 if (offset
< se
->start_page
)
215 else if (offset
>= se
->start_page
+ se
->nr_pages
)
220 /* It *must* be present */
225 * swap allocation tell device that a cluster of swap can now be discarded,
226 * to allow the swap device to optimize its wear-levelling.
228 static void discard_swap_cluster(struct swap_info_struct
*si
,
229 pgoff_t start_page
, pgoff_t nr_pages
)
231 struct swap_extent
*se
= offset_to_swap_extent(si
, start_page
);
234 pgoff_t offset
= start_page
- se
->start_page
;
235 sector_t start_block
= se
->start_block
+ offset
;
236 sector_t nr_blocks
= se
->nr_pages
- offset
;
238 if (nr_blocks
> nr_pages
)
239 nr_blocks
= nr_pages
;
240 start_page
+= nr_blocks
;
241 nr_pages
-= nr_blocks
;
243 start_block
<<= PAGE_SHIFT
- 9;
244 nr_blocks
<<= PAGE_SHIFT
- 9;
245 if (blkdev_issue_discard(si
->bdev
, start_block
,
246 nr_blocks
, GFP_NOIO
, 0))
253 #ifdef CONFIG_THP_SWAP
254 #define SWAPFILE_CLUSTER HPAGE_PMD_NR
256 #define swap_entry_size(size) (size)
258 #define SWAPFILE_CLUSTER 256
261 * Define swap_entry_size() as constant to let compiler to optimize
262 * out some code if !CONFIG_THP_SWAP
264 #define swap_entry_size(size) 1
266 #define LATENCY_LIMIT 256
268 static inline void cluster_set_flag(struct swap_cluster_info
*info
,
274 static inline unsigned int cluster_count(struct swap_cluster_info
*info
)
279 static inline void cluster_set_count(struct swap_cluster_info
*info
,
285 static inline void cluster_set_count_flag(struct swap_cluster_info
*info
,
286 unsigned int c
, unsigned int f
)
292 static inline unsigned int cluster_next(struct swap_cluster_info
*info
)
297 static inline void cluster_set_next(struct swap_cluster_info
*info
,
303 static inline void cluster_set_next_flag(struct swap_cluster_info
*info
,
304 unsigned int n
, unsigned int f
)
310 static inline bool cluster_is_free(struct swap_cluster_info
*info
)
312 return info
->flags
& CLUSTER_FLAG_FREE
;
315 static inline bool cluster_is_null(struct swap_cluster_info
*info
)
317 return info
->flags
& CLUSTER_FLAG_NEXT_NULL
;
320 static inline void cluster_set_null(struct swap_cluster_info
*info
)
322 info
->flags
= CLUSTER_FLAG_NEXT_NULL
;
326 static inline bool cluster_is_huge(struct swap_cluster_info
*info
)
328 if (IS_ENABLED(CONFIG_THP_SWAP
))
329 return info
->flags
& CLUSTER_FLAG_HUGE
;
333 static inline void cluster_clear_huge(struct swap_cluster_info
*info
)
335 info
->flags
&= ~CLUSTER_FLAG_HUGE
;
338 static inline struct swap_cluster_info
*lock_cluster(struct swap_info_struct
*si
,
339 unsigned long offset
)
341 struct swap_cluster_info
*ci
;
343 ci
= si
->cluster_info
;
345 ci
+= offset
/ SWAPFILE_CLUSTER
;
346 spin_lock(&ci
->lock
);
351 static inline void unlock_cluster(struct swap_cluster_info
*ci
)
354 spin_unlock(&ci
->lock
);
358 * Determine the locking method in use for this device. Return
359 * swap_cluster_info if SSD-style cluster-based locking is in place.
361 static inline struct swap_cluster_info
*lock_cluster_or_swap_info(
362 struct swap_info_struct
*si
, unsigned long offset
)
364 struct swap_cluster_info
*ci
;
366 /* Try to use fine-grained SSD-style locking if available: */
367 ci
= lock_cluster(si
, offset
);
368 /* Otherwise, fall back to traditional, coarse locking: */
370 spin_lock(&si
->lock
);
375 static inline void unlock_cluster_or_swap_info(struct swap_info_struct
*si
,
376 struct swap_cluster_info
*ci
)
381 spin_unlock(&si
->lock
);
384 static inline bool cluster_list_empty(struct swap_cluster_list
*list
)
386 return cluster_is_null(&list
->head
);
389 static inline unsigned int cluster_list_first(struct swap_cluster_list
*list
)
391 return cluster_next(&list
->head
);
394 static void cluster_list_init(struct swap_cluster_list
*list
)
396 cluster_set_null(&list
->head
);
397 cluster_set_null(&list
->tail
);
400 static void cluster_list_add_tail(struct swap_cluster_list
*list
,
401 struct swap_cluster_info
*ci
,
404 if (cluster_list_empty(list
)) {
405 cluster_set_next_flag(&list
->head
, idx
, 0);
406 cluster_set_next_flag(&list
->tail
, idx
, 0);
408 struct swap_cluster_info
*ci_tail
;
409 unsigned int tail
= cluster_next(&list
->tail
);
412 * Nested cluster lock, but both cluster locks are
413 * only acquired when we held swap_info_struct->lock
416 spin_lock_nested(&ci_tail
->lock
, SINGLE_DEPTH_NESTING
);
417 cluster_set_next(ci_tail
, idx
);
418 spin_unlock(&ci_tail
->lock
);
419 cluster_set_next_flag(&list
->tail
, idx
, 0);
423 static unsigned int cluster_list_del_first(struct swap_cluster_list
*list
,
424 struct swap_cluster_info
*ci
)
428 idx
= cluster_next(&list
->head
);
429 if (cluster_next(&list
->tail
) == idx
) {
430 cluster_set_null(&list
->head
);
431 cluster_set_null(&list
->tail
);
433 cluster_set_next_flag(&list
->head
,
434 cluster_next(&ci
[idx
]), 0);
439 /* Add a cluster to discard list and schedule it to do discard */
440 static void swap_cluster_schedule_discard(struct swap_info_struct
*si
,
444 * If scan_swap_map() can't find a free cluster, it will check
445 * si->swap_map directly. To make sure the discarding cluster isn't
446 * taken by scan_swap_map(), mark the swap entries bad (occupied). It
447 * will be cleared after discard
449 memset(si
->swap_map
+ idx
* SWAPFILE_CLUSTER
,
450 SWAP_MAP_BAD
, SWAPFILE_CLUSTER
);
452 cluster_list_add_tail(&si
->discard_clusters
, si
->cluster_info
, idx
);
454 schedule_work(&si
->discard_work
);
457 static void __free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
459 struct swap_cluster_info
*ci
= si
->cluster_info
;
461 cluster_set_flag(ci
+ idx
, CLUSTER_FLAG_FREE
);
462 cluster_list_add_tail(&si
->free_clusters
, ci
, idx
);
466 * Doing discard actually. After a cluster discard is finished, the cluster
467 * will be added to free cluster list. caller should hold si->lock.
469 static void swap_do_scheduled_discard(struct swap_info_struct
*si
)
471 struct swap_cluster_info
*info
, *ci
;
474 info
= si
->cluster_info
;
476 while (!cluster_list_empty(&si
->discard_clusters
)) {
477 idx
= cluster_list_del_first(&si
->discard_clusters
, info
);
478 spin_unlock(&si
->lock
);
480 discard_swap_cluster(si
, idx
* SWAPFILE_CLUSTER
,
483 spin_lock(&si
->lock
);
484 ci
= lock_cluster(si
, idx
* SWAPFILE_CLUSTER
);
485 __free_cluster(si
, idx
);
486 memset(si
->swap_map
+ idx
* SWAPFILE_CLUSTER
,
487 0, SWAPFILE_CLUSTER
);
492 static void swap_discard_work(struct work_struct
*work
)
494 struct swap_info_struct
*si
;
496 si
= container_of(work
, struct swap_info_struct
, discard_work
);
498 spin_lock(&si
->lock
);
499 swap_do_scheduled_discard(si
);
500 spin_unlock(&si
->lock
);
503 static void alloc_cluster(struct swap_info_struct
*si
, unsigned long idx
)
505 struct swap_cluster_info
*ci
= si
->cluster_info
;
507 VM_BUG_ON(cluster_list_first(&si
->free_clusters
) != idx
);
508 cluster_list_del_first(&si
->free_clusters
, ci
);
509 cluster_set_count_flag(ci
+ idx
, 0, 0);
512 static void free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
514 struct swap_cluster_info
*ci
= si
->cluster_info
+ idx
;
516 VM_BUG_ON(cluster_count(ci
) != 0);
518 * If the swap is discardable, prepare discard the cluster
519 * instead of free it immediately. The cluster will be freed
522 if ((si
->flags
& (SWP_WRITEOK
| SWP_PAGE_DISCARD
)) ==
523 (SWP_WRITEOK
| SWP_PAGE_DISCARD
)) {
524 swap_cluster_schedule_discard(si
, idx
);
528 __free_cluster(si
, idx
);
532 * The cluster corresponding to page_nr will be used. The cluster will be
533 * removed from free cluster list and its usage counter will be increased.
535 static void inc_cluster_info_page(struct swap_info_struct
*p
,
536 struct swap_cluster_info
*cluster_info
, unsigned long page_nr
)
538 unsigned long idx
= page_nr
/ SWAPFILE_CLUSTER
;
542 if (cluster_is_free(&cluster_info
[idx
]))
543 alloc_cluster(p
, idx
);
545 VM_BUG_ON(cluster_count(&cluster_info
[idx
]) >= SWAPFILE_CLUSTER
);
546 cluster_set_count(&cluster_info
[idx
],
547 cluster_count(&cluster_info
[idx
]) + 1);
551 * The cluster corresponding to page_nr decreases one usage. If the usage
552 * counter becomes 0, which means no page in the cluster is in using, we can
553 * optionally discard the cluster and add it to free cluster list.
555 static void dec_cluster_info_page(struct swap_info_struct
*p
,
556 struct swap_cluster_info
*cluster_info
, unsigned long page_nr
)
558 unsigned long idx
= page_nr
/ SWAPFILE_CLUSTER
;
563 VM_BUG_ON(cluster_count(&cluster_info
[idx
]) == 0);
564 cluster_set_count(&cluster_info
[idx
],
565 cluster_count(&cluster_info
[idx
]) - 1);
567 if (cluster_count(&cluster_info
[idx
]) == 0)
568 free_cluster(p
, idx
);
572 * It's possible scan_swap_map() uses a free cluster in the middle of free
573 * cluster list. Avoiding such abuse to avoid list corruption.
576 scan_swap_map_ssd_cluster_conflict(struct swap_info_struct
*si
,
577 unsigned long offset
)
579 struct percpu_cluster
*percpu_cluster
;
582 offset
/= SWAPFILE_CLUSTER
;
583 conflict
= !cluster_list_empty(&si
->free_clusters
) &&
584 offset
!= cluster_list_first(&si
->free_clusters
) &&
585 cluster_is_free(&si
->cluster_info
[offset
]);
590 percpu_cluster
= this_cpu_ptr(si
->percpu_cluster
);
591 cluster_set_null(&percpu_cluster
->index
);
596 * Try to get a swap entry from current cpu's swap entry pool (a cluster). This
597 * might involve allocating a new cluster for current CPU too.
599 static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct
*si
,
600 unsigned long *offset
, unsigned long *scan_base
)
602 struct percpu_cluster
*cluster
;
603 struct swap_cluster_info
*ci
;
604 unsigned long tmp
, max
;
607 cluster
= this_cpu_ptr(si
->percpu_cluster
);
608 if (cluster_is_null(&cluster
->index
)) {
609 if (!cluster_list_empty(&si
->free_clusters
)) {
610 cluster
->index
= si
->free_clusters
.head
;
611 cluster
->next
= cluster_next(&cluster
->index
) *
613 } else if (!cluster_list_empty(&si
->discard_clusters
)) {
615 * we don't have free cluster but have some clusters in
616 * discarding, do discard now and reclaim them
618 swap_do_scheduled_discard(si
);
619 *scan_base
= *offset
= si
->cluster_next
;
626 * Other CPUs can use our cluster if they can't find a free cluster,
627 * check if there is still free entry in the cluster
630 max
= min_t(unsigned long, si
->max
,
631 (cluster_next(&cluster
->index
) + 1) * SWAPFILE_CLUSTER
);
633 ci
= lock_cluster(si
, tmp
);
635 if (!si
->swap_map
[tmp
])
642 cluster_set_null(&cluster
->index
);
645 cluster
->next
= tmp
+ 1;
651 static void __del_from_avail_list(struct swap_info_struct
*p
)
656 plist_del(&p
->avail_lists
[nid
], &swap_avail_heads
[nid
]);
659 static void del_from_avail_list(struct swap_info_struct
*p
)
661 spin_lock(&swap_avail_lock
);
662 __del_from_avail_list(p
);
663 spin_unlock(&swap_avail_lock
);
666 static void swap_range_alloc(struct swap_info_struct
*si
, unsigned long offset
,
667 unsigned int nr_entries
)
669 unsigned int end
= offset
+ nr_entries
- 1;
671 if (offset
== si
->lowest_bit
)
672 si
->lowest_bit
+= nr_entries
;
673 if (end
== si
->highest_bit
)
674 si
->highest_bit
-= nr_entries
;
675 si
->inuse_pages
+= nr_entries
;
676 if (si
->inuse_pages
== si
->pages
) {
677 si
->lowest_bit
= si
->max
;
679 del_from_avail_list(si
);
683 static void add_to_avail_list(struct swap_info_struct
*p
)
687 spin_lock(&swap_avail_lock
);
689 WARN_ON(!plist_node_empty(&p
->avail_lists
[nid
]));
690 plist_add(&p
->avail_lists
[nid
], &swap_avail_heads
[nid
]);
692 spin_unlock(&swap_avail_lock
);
695 static void swap_range_free(struct swap_info_struct
*si
, unsigned long offset
,
696 unsigned int nr_entries
)
698 unsigned long end
= offset
+ nr_entries
- 1;
699 void (*swap_slot_free_notify
)(struct block_device
*, unsigned long);
701 if (offset
< si
->lowest_bit
)
702 si
->lowest_bit
= offset
;
703 if (end
> si
->highest_bit
) {
704 bool was_full
= !si
->highest_bit
;
706 si
->highest_bit
= end
;
707 if (was_full
&& (si
->flags
& SWP_WRITEOK
))
708 add_to_avail_list(si
);
710 atomic_long_add(nr_entries
, &nr_swap_pages
);
711 si
->inuse_pages
-= nr_entries
;
712 if (si
->flags
& SWP_BLKDEV
)
713 swap_slot_free_notify
=
714 si
->bdev
->bd_disk
->fops
->swap_slot_free_notify
;
716 swap_slot_free_notify
= NULL
;
717 while (offset
<= end
) {
718 frontswap_invalidate_page(si
->type
, offset
);
719 if (swap_slot_free_notify
)
720 swap_slot_free_notify(si
->bdev
, offset
);
725 static int scan_swap_map_slots(struct swap_info_struct
*si
,
726 unsigned char usage
, int nr
,
729 struct swap_cluster_info
*ci
;
730 unsigned long offset
;
731 unsigned long scan_base
;
732 unsigned long last_in_cluster
= 0;
733 int latency_ration
= LATENCY_LIMIT
;
735 bool scanned_many
= false;
738 * We try to cluster swap pages by allocating them sequentially
739 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
740 * way, however, we resort to first-free allocation, starting
741 * a new cluster. This prevents us from scattering swap pages
742 * all over the entire swap partition, so that we reduce
743 * overall disk seek times between swap pages. -- sct
744 * But we do now try to find an empty cluster. -Andrea
745 * And we let swap pages go all over an SSD partition. Hugh
748 si
->flags
+= SWP_SCANNING
;
749 scan_base
= offset
= si
->cluster_next
;
752 if (si
->cluster_info
) {
753 if (!scan_swap_map_try_ssd_cluster(si
, &offset
, &scan_base
))
755 } else if (unlikely(!si
->cluster_nr
--)) {
756 if (si
->pages
- si
->inuse_pages
< SWAPFILE_CLUSTER
) {
757 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
761 spin_unlock(&si
->lock
);
764 * If seek is expensive, start searching for new cluster from
765 * start of partition, to minimize the span of allocated swap.
766 * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info
767 * case, just handled by scan_swap_map_try_ssd_cluster() above.
769 scan_base
= offset
= si
->lowest_bit
;
770 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
- 1;
772 /* Locate the first empty (unaligned) cluster */
773 for (; last_in_cluster
<= si
->highest_bit
; offset
++) {
774 if (si
->swap_map
[offset
])
775 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
;
776 else if (offset
== last_in_cluster
) {
777 spin_lock(&si
->lock
);
778 offset
-= SWAPFILE_CLUSTER
- 1;
779 si
->cluster_next
= offset
;
780 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
783 if (unlikely(--latency_ration
< 0)) {
785 latency_ration
= LATENCY_LIMIT
;
790 spin_lock(&si
->lock
);
791 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
795 if (si
->cluster_info
) {
796 while (scan_swap_map_ssd_cluster_conflict(si
, offset
)) {
797 /* take a break if we already got some slots */
800 if (!scan_swap_map_try_ssd_cluster(si
, &offset
,
805 if (!(si
->flags
& SWP_WRITEOK
))
807 if (!si
->highest_bit
)
809 if (offset
> si
->highest_bit
)
810 scan_base
= offset
= si
->lowest_bit
;
812 ci
= lock_cluster(si
, offset
);
813 /* reuse swap entry of cache-only swap if not busy. */
814 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
817 spin_unlock(&si
->lock
);
818 swap_was_freed
= __try_to_reclaim_swap(si
, offset
, TTRS_ANYWAY
);
819 spin_lock(&si
->lock
);
820 /* entry was freed successfully, try to use this again */
823 goto scan
; /* check next one */
826 if (si
->swap_map
[offset
]) {
833 si
->swap_map
[offset
] = usage
;
834 inc_cluster_info_page(si
, si
->cluster_info
, offset
);
837 swap_range_alloc(si
, offset
, 1);
838 si
->cluster_next
= offset
+ 1;
839 slots
[n_ret
++] = swp_entry(si
->type
, offset
);
841 /* got enough slots or reach max slots? */
842 if ((n_ret
== nr
) || (offset
>= si
->highest_bit
))
845 /* search for next available slot */
847 /* time to take a break? */
848 if (unlikely(--latency_ration
< 0)) {
851 spin_unlock(&si
->lock
);
853 spin_lock(&si
->lock
);
854 latency_ration
= LATENCY_LIMIT
;
857 /* try to get more slots in cluster */
858 if (si
->cluster_info
) {
859 if (scan_swap_map_try_ssd_cluster(si
, &offset
, &scan_base
))
861 } else if (si
->cluster_nr
&& !si
->swap_map
[++offset
]) {
862 /* non-ssd case, still more slots in cluster? */
868 * Even if there's no free clusters available (fragmented),
869 * try to scan a little more quickly with lock held unless we
870 * have scanned too many slots already.
873 unsigned long scan_limit
;
875 if (offset
< scan_base
)
876 scan_limit
= scan_base
;
878 scan_limit
= si
->highest_bit
;
879 for (; offset
<= scan_limit
&& --latency_ration
> 0;
881 if (!si
->swap_map
[offset
])
887 si
->flags
-= SWP_SCANNING
;
891 spin_unlock(&si
->lock
);
892 while (++offset
<= si
->highest_bit
) {
893 if (!si
->swap_map
[offset
]) {
894 spin_lock(&si
->lock
);
897 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
898 spin_lock(&si
->lock
);
901 if (unlikely(--latency_ration
< 0)) {
903 latency_ration
= LATENCY_LIMIT
;
907 offset
= si
->lowest_bit
;
908 while (offset
< scan_base
) {
909 if (!si
->swap_map
[offset
]) {
910 spin_lock(&si
->lock
);
913 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
914 spin_lock(&si
->lock
);
917 if (unlikely(--latency_ration
< 0)) {
919 latency_ration
= LATENCY_LIMIT
;
924 spin_lock(&si
->lock
);
927 si
->flags
-= SWP_SCANNING
;
931 static int swap_alloc_cluster(struct swap_info_struct
*si
, swp_entry_t
*slot
)
934 struct swap_cluster_info
*ci
;
935 unsigned long offset
, i
;
939 * Should not even be attempting cluster allocations when huge
940 * page swap is disabled. Warn and fail the allocation.
942 if (!IS_ENABLED(CONFIG_THP_SWAP
)) {
947 if (cluster_list_empty(&si
->free_clusters
))
950 idx
= cluster_list_first(&si
->free_clusters
);
951 offset
= idx
* SWAPFILE_CLUSTER
;
952 ci
= lock_cluster(si
, offset
);
953 alloc_cluster(si
, idx
);
954 cluster_set_count_flag(ci
, SWAPFILE_CLUSTER
, CLUSTER_FLAG_HUGE
);
956 map
= si
->swap_map
+ offset
;
957 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++)
958 map
[i
] = SWAP_HAS_CACHE
;
960 swap_range_alloc(si
, offset
, SWAPFILE_CLUSTER
);
961 *slot
= swp_entry(si
->type
, offset
);
966 static void swap_free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
968 unsigned long offset
= idx
* SWAPFILE_CLUSTER
;
969 struct swap_cluster_info
*ci
;
971 ci
= lock_cluster(si
, offset
);
972 memset(si
->swap_map
+ offset
, 0, SWAPFILE_CLUSTER
);
973 cluster_set_count_flag(ci
, 0, 0);
974 free_cluster(si
, idx
);
976 swap_range_free(si
, offset
, SWAPFILE_CLUSTER
);
979 static unsigned long scan_swap_map(struct swap_info_struct
*si
,
985 n_ret
= scan_swap_map_slots(si
, usage
, 1, &entry
);
988 return swp_offset(entry
);
994 int get_swap_pages(int n_goal
, swp_entry_t swp_entries
[], int entry_size
)
996 unsigned long size
= swap_entry_size(entry_size
);
997 struct swap_info_struct
*si
, *next
;
1002 /* Only single cluster request supported */
1003 WARN_ON_ONCE(n_goal
> 1 && size
== SWAPFILE_CLUSTER
);
1005 avail_pgs
= atomic_long_read(&nr_swap_pages
) / size
;
1009 n_goal
= min3((long)n_goal
, (long)SWAP_BATCH
, avail_pgs
);
1011 atomic_long_sub(n_goal
* size
, &nr_swap_pages
);
1013 spin_lock(&swap_avail_lock
);
1016 node
= numa_node_id();
1017 plist_for_each_entry_safe(si
, next
, &swap_avail_heads
[node
], avail_lists
[node
]) {
1018 /* requeue si to after same-priority siblings */
1019 plist_requeue(&si
->avail_lists
[node
], &swap_avail_heads
[node
]);
1020 spin_unlock(&swap_avail_lock
);
1021 spin_lock(&si
->lock
);
1022 if (!si
->highest_bit
|| !(si
->flags
& SWP_WRITEOK
)) {
1023 spin_lock(&swap_avail_lock
);
1024 if (plist_node_empty(&si
->avail_lists
[node
])) {
1025 spin_unlock(&si
->lock
);
1028 WARN(!si
->highest_bit
,
1029 "swap_info %d in list but !highest_bit\n",
1031 WARN(!(si
->flags
& SWP_WRITEOK
),
1032 "swap_info %d in list but !SWP_WRITEOK\n",
1034 __del_from_avail_list(si
);
1035 spin_unlock(&si
->lock
);
1038 if (size
== SWAPFILE_CLUSTER
) {
1039 if (!(si
->flags
& SWP_FS
))
1040 n_ret
= swap_alloc_cluster(si
, swp_entries
);
1042 n_ret
= scan_swap_map_slots(si
, SWAP_HAS_CACHE
,
1043 n_goal
, swp_entries
);
1044 spin_unlock(&si
->lock
);
1045 if (n_ret
|| size
== SWAPFILE_CLUSTER
)
1047 pr_debug("scan_swap_map of si %d failed to find offset\n",
1050 spin_lock(&swap_avail_lock
);
1053 * if we got here, it's likely that si was almost full before,
1054 * and since scan_swap_map() can drop the si->lock, multiple
1055 * callers probably all tried to get a page from the same si
1056 * and it filled up before we could get one; or, the si filled
1057 * up between us dropping swap_avail_lock and taking si->lock.
1058 * Since we dropped the swap_avail_lock, the swap_avail_head
1059 * list may have been modified; so if next is still in the
1060 * swap_avail_head list then try it, otherwise start over
1061 * if we have not gotten any slots.
1063 if (plist_node_empty(&next
->avail_lists
[node
]))
1067 spin_unlock(&swap_avail_lock
);
1071 atomic_long_add((long)(n_goal
- n_ret
) * size
,
1077 /* The only caller of this function is now suspend routine */
1078 swp_entry_t
get_swap_page_of_type(int type
)
1080 struct swap_info_struct
*si
= swap_type_to_swap_info(type
);
1086 spin_lock(&si
->lock
);
1087 if (si
->flags
& SWP_WRITEOK
) {
1088 atomic_long_dec(&nr_swap_pages
);
1089 /* This is called for allocating swap entry, not cache */
1090 offset
= scan_swap_map(si
, 1);
1092 spin_unlock(&si
->lock
);
1093 return swp_entry(type
, offset
);
1095 atomic_long_inc(&nr_swap_pages
);
1097 spin_unlock(&si
->lock
);
1099 return (swp_entry_t
) {0};
1102 static struct swap_info_struct
*__swap_info_get(swp_entry_t entry
)
1104 struct swap_info_struct
*p
;
1105 unsigned long offset
;
1109 p
= swp_swap_info(entry
);
1112 if (!(p
->flags
& SWP_USED
))
1114 offset
= swp_offset(entry
);
1115 if (offset
>= p
->max
)
1120 pr_err("swap_info_get: %s%08lx\n", Bad_offset
, entry
.val
);
1123 pr_err("swap_info_get: %s%08lx\n", Unused_file
, entry
.val
);
1126 pr_err("swap_info_get: %s%08lx\n", Bad_file
, entry
.val
);
1131 static struct swap_info_struct
*_swap_info_get(swp_entry_t entry
)
1133 struct swap_info_struct
*p
;
1135 p
= __swap_info_get(entry
);
1138 if (!p
->swap_map
[swp_offset(entry
)])
1143 pr_err("swap_info_get: %s%08lx\n", Unused_offset
, entry
.val
);
1149 static struct swap_info_struct
*swap_info_get(swp_entry_t entry
)
1151 struct swap_info_struct
*p
;
1153 p
= _swap_info_get(entry
);
1155 spin_lock(&p
->lock
);
1159 static struct swap_info_struct
*swap_info_get_cont(swp_entry_t entry
,
1160 struct swap_info_struct
*q
)
1162 struct swap_info_struct
*p
;
1164 p
= _swap_info_get(entry
);
1168 spin_unlock(&q
->lock
);
1170 spin_lock(&p
->lock
);
1175 static unsigned char __swap_entry_free_locked(struct swap_info_struct
*p
,
1176 unsigned long offset
,
1177 unsigned char usage
)
1179 unsigned char count
;
1180 unsigned char has_cache
;
1182 count
= p
->swap_map
[offset
];
1184 has_cache
= count
& SWAP_HAS_CACHE
;
1185 count
&= ~SWAP_HAS_CACHE
;
1187 if (usage
== SWAP_HAS_CACHE
) {
1188 VM_BUG_ON(!has_cache
);
1190 } else if (count
== SWAP_MAP_SHMEM
) {
1192 * Or we could insist on shmem.c using a special
1193 * swap_shmem_free() and free_shmem_swap_and_cache()...
1196 } else if ((count
& ~COUNT_CONTINUED
) <= SWAP_MAP_MAX
) {
1197 if (count
== COUNT_CONTINUED
) {
1198 if (swap_count_continued(p
, offset
, count
))
1199 count
= SWAP_MAP_MAX
| COUNT_CONTINUED
;
1201 count
= SWAP_MAP_MAX
;
1206 usage
= count
| has_cache
;
1207 p
->swap_map
[offset
] = usage
? : SWAP_HAS_CACHE
;
1213 * Check whether swap entry is valid in the swap device. If so,
1214 * return pointer to swap_info_struct, and keep the swap entry valid
1215 * via preventing the swap device from being swapoff, until
1216 * put_swap_device() is called. Otherwise return NULL.
1218 * The entirety of the RCU read critical section must come before the
1219 * return from or after the call to synchronize_rcu() in
1220 * enable_swap_info() or swapoff(). So if "si->flags & SWP_VALID" is
1221 * true, the si->map, si->cluster_info, etc. must be valid in the
1224 * Notice that swapoff or swapoff+swapon can still happen before the
1225 * rcu_read_lock() in get_swap_device() or after the rcu_read_unlock()
1226 * in put_swap_device() if there isn't any other way to prevent
1227 * swapoff, such as page lock, page table lock, etc. The caller must
1228 * be prepared for that. For example, the following situation is
1233 * ... swapoff+swapon
1234 * __read_swap_cache_async()
1235 * swapcache_prepare()
1236 * __swap_duplicate()
1238 * // verify PTE not changed
1240 * In __swap_duplicate(), the swap_map need to be checked before
1241 * changing partly because the specified swap entry may be for another
1242 * swap device which has been swapoff. And in do_swap_page(), after
1243 * the page is read from the swap device, the PTE is verified not
1244 * changed with the page table locked to check whether the swap device
1245 * has been swapoff or swapoff+swapon.
1247 struct swap_info_struct
*get_swap_device(swp_entry_t entry
)
1249 struct swap_info_struct
*si
;
1250 unsigned long offset
;
1254 si
= swp_swap_info(entry
);
1259 if (!(si
->flags
& SWP_VALID
))
1261 offset
= swp_offset(entry
);
1262 if (offset
>= si
->max
)
1267 pr_err("%s: %s%08lx\n", __func__
, Bad_file
, entry
.val
);
1275 static unsigned char __swap_entry_free(struct swap_info_struct
*p
,
1276 swp_entry_t entry
, unsigned char usage
)
1278 struct swap_cluster_info
*ci
;
1279 unsigned long offset
= swp_offset(entry
);
1281 ci
= lock_cluster_or_swap_info(p
, offset
);
1282 usage
= __swap_entry_free_locked(p
, offset
, usage
);
1283 unlock_cluster_or_swap_info(p
, ci
);
1285 free_swap_slot(entry
);
1290 static void swap_entry_free(struct swap_info_struct
*p
, swp_entry_t entry
)
1292 struct swap_cluster_info
*ci
;
1293 unsigned long offset
= swp_offset(entry
);
1294 unsigned char count
;
1296 ci
= lock_cluster(p
, offset
);
1297 count
= p
->swap_map
[offset
];
1298 VM_BUG_ON(count
!= SWAP_HAS_CACHE
);
1299 p
->swap_map
[offset
] = 0;
1300 dec_cluster_info_page(p
, p
->cluster_info
, offset
);
1303 mem_cgroup_uncharge_swap(entry
, 1);
1304 swap_range_free(p
, offset
, 1);
1308 * Caller has made sure that the swap device corresponding to entry
1309 * is still around or has not been recycled.
1311 void swap_free(swp_entry_t entry
)
1313 struct swap_info_struct
*p
;
1315 p
= _swap_info_get(entry
);
1317 __swap_entry_free(p
, entry
, 1);
1321 * Called after dropping swapcache to decrease refcnt to swap entries.
1323 void put_swap_page(struct page
*page
, swp_entry_t entry
)
1325 unsigned long offset
= swp_offset(entry
);
1326 unsigned long idx
= offset
/ SWAPFILE_CLUSTER
;
1327 struct swap_cluster_info
*ci
;
1328 struct swap_info_struct
*si
;
1330 unsigned int i
, free_entries
= 0;
1332 int size
= swap_entry_size(hpage_nr_pages(page
));
1334 si
= _swap_info_get(entry
);
1338 ci
= lock_cluster_or_swap_info(si
, offset
);
1339 if (size
== SWAPFILE_CLUSTER
) {
1340 VM_BUG_ON(!cluster_is_huge(ci
));
1341 map
= si
->swap_map
+ offset
;
1342 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++) {
1344 VM_BUG_ON(!(val
& SWAP_HAS_CACHE
));
1345 if (val
== SWAP_HAS_CACHE
)
1348 cluster_clear_huge(ci
);
1349 if (free_entries
== SWAPFILE_CLUSTER
) {
1350 unlock_cluster_or_swap_info(si
, ci
);
1351 spin_lock(&si
->lock
);
1352 mem_cgroup_uncharge_swap(entry
, SWAPFILE_CLUSTER
);
1353 swap_free_cluster(si
, idx
);
1354 spin_unlock(&si
->lock
);
1358 for (i
= 0; i
< size
; i
++, entry
.val
++) {
1359 if (!__swap_entry_free_locked(si
, offset
+ i
, SWAP_HAS_CACHE
)) {
1360 unlock_cluster_or_swap_info(si
, ci
);
1361 free_swap_slot(entry
);
1364 lock_cluster_or_swap_info(si
, offset
);
1367 unlock_cluster_or_swap_info(si
, ci
);
1370 #ifdef CONFIG_THP_SWAP
1371 int split_swap_cluster(swp_entry_t entry
)
1373 struct swap_info_struct
*si
;
1374 struct swap_cluster_info
*ci
;
1375 unsigned long offset
= swp_offset(entry
);
1377 si
= _swap_info_get(entry
);
1380 ci
= lock_cluster(si
, offset
);
1381 cluster_clear_huge(ci
);
1387 static int swp_entry_cmp(const void *ent1
, const void *ent2
)
1389 const swp_entry_t
*e1
= ent1
, *e2
= ent2
;
1391 return (int)swp_type(*e1
) - (int)swp_type(*e2
);
1394 void swapcache_free_entries(swp_entry_t
*entries
, int n
)
1396 struct swap_info_struct
*p
, *prev
;
1406 * Sort swap entries by swap device, so each lock is only taken once.
1407 * nr_swapfiles isn't absolutely correct, but the overhead of sort() is
1408 * so low that it isn't necessary to optimize further.
1410 if (nr_swapfiles
> 1)
1411 sort(entries
, n
, sizeof(entries
[0]), swp_entry_cmp
, NULL
);
1412 for (i
= 0; i
< n
; ++i
) {
1413 p
= swap_info_get_cont(entries
[i
], prev
);
1415 swap_entry_free(p
, entries
[i
]);
1419 spin_unlock(&p
->lock
);
1423 * How many references to page are currently swapped out?
1424 * This does not give an exact answer when swap count is continued,
1425 * but does include the high COUNT_CONTINUED flag to allow for that.
1427 int page_swapcount(struct page
*page
)
1430 struct swap_info_struct
*p
;
1431 struct swap_cluster_info
*ci
;
1433 unsigned long offset
;
1435 entry
.val
= page_private(page
);
1436 p
= _swap_info_get(entry
);
1438 offset
= swp_offset(entry
);
1439 ci
= lock_cluster_or_swap_info(p
, offset
);
1440 count
= swap_count(p
->swap_map
[offset
]);
1441 unlock_cluster_or_swap_info(p
, ci
);
1446 int __swap_count(swp_entry_t entry
)
1448 struct swap_info_struct
*si
;
1449 pgoff_t offset
= swp_offset(entry
);
1452 si
= get_swap_device(entry
);
1454 count
= swap_count(si
->swap_map
[offset
]);
1455 put_swap_device(si
);
1460 static int swap_swapcount(struct swap_info_struct
*si
, swp_entry_t entry
)
1463 pgoff_t offset
= swp_offset(entry
);
1464 struct swap_cluster_info
*ci
;
1466 ci
= lock_cluster_or_swap_info(si
, offset
);
1467 count
= swap_count(si
->swap_map
[offset
]);
1468 unlock_cluster_or_swap_info(si
, ci
);
1473 * How many references to @entry are currently swapped out?
1474 * This does not give an exact answer when swap count is continued,
1475 * but does include the high COUNT_CONTINUED flag to allow for that.
1477 int __swp_swapcount(swp_entry_t entry
)
1480 struct swap_info_struct
*si
;
1482 si
= get_swap_device(entry
);
1484 count
= swap_swapcount(si
, entry
);
1485 put_swap_device(si
);
1491 * How many references to @entry are currently swapped out?
1492 * This considers COUNT_CONTINUED so it returns exact answer.
1494 int swp_swapcount(swp_entry_t entry
)
1496 int count
, tmp_count
, n
;
1497 struct swap_info_struct
*p
;
1498 struct swap_cluster_info
*ci
;
1503 p
= _swap_info_get(entry
);
1507 offset
= swp_offset(entry
);
1509 ci
= lock_cluster_or_swap_info(p
, offset
);
1511 count
= swap_count(p
->swap_map
[offset
]);
1512 if (!(count
& COUNT_CONTINUED
))
1515 count
&= ~COUNT_CONTINUED
;
1516 n
= SWAP_MAP_MAX
+ 1;
1518 page
= vmalloc_to_page(p
->swap_map
+ offset
);
1519 offset
&= ~PAGE_MASK
;
1520 VM_BUG_ON(page_private(page
) != SWP_CONTINUED
);
1523 page
= list_next_entry(page
, lru
);
1524 map
= kmap_atomic(page
);
1525 tmp_count
= map
[offset
];
1528 count
+= (tmp_count
& ~COUNT_CONTINUED
) * n
;
1529 n
*= (SWAP_CONT_MAX
+ 1);
1530 } while (tmp_count
& COUNT_CONTINUED
);
1532 unlock_cluster_or_swap_info(p
, ci
);
1536 static bool swap_page_trans_huge_swapped(struct swap_info_struct
*si
,
1539 struct swap_cluster_info
*ci
;
1540 unsigned char *map
= si
->swap_map
;
1541 unsigned long roffset
= swp_offset(entry
);
1542 unsigned long offset
= round_down(roffset
, SWAPFILE_CLUSTER
);
1546 ci
= lock_cluster_or_swap_info(si
, offset
);
1547 if (!ci
|| !cluster_is_huge(ci
)) {
1548 if (swap_count(map
[roffset
]))
1552 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++) {
1553 if (swap_count(map
[offset
+ i
])) {
1559 unlock_cluster_or_swap_info(si
, ci
);
1563 static bool page_swapped(struct page
*page
)
1566 struct swap_info_struct
*si
;
1568 if (!IS_ENABLED(CONFIG_THP_SWAP
) || likely(!PageTransCompound(page
)))
1569 return page_swapcount(page
) != 0;
1571 page
= compound_head(page
);
1572 entry
.val
= page_private(page
);
1573 si
= _swap_info_get(entry
);
1575 return swap_page_trans_huge_swapped(si
, entry
);
1579 static int page_trans_huge_map_swapcount(struct page
*page
, int *total_mapcount
,
1580 int *total_swapcount
)
1582 int i
, map_swapcount
, _total_mapcount
, _total_swapcount
;
1583 unsigned long offset
= 0;
1584 struct swap_info_struct
*si
;
1585 struct swap_cluster_info
*ci
= NULL
;
1586 unsigned char *map
= NULL
;
1587 int mapcount
, swapcount
= 0;
1589 /* hugetlbfs shouldn't call it */
1590 VM_BUG_ON_PAGE(PageHuge(page
), page
);
1592 if (!IS_ENABLED(CONFIG_THP_SWAP
) || likely(!PageTransCompound(page
))) {
1593 mapcount
= page_trans_huge_mapcount(page
, total_mapcount
);
1594 if (PageSwapCache(page
))
1595 swapcount
= page_swapcount(page
);
1596 if (total_swapcount
)
1597 *total_swapcount
= swapcount
;
1598 return mapcount
+ swapcount
;
1601 page
= compound_head(page
);
1603 _total_mapcount
= _total_swapcount
= map_swapcount
= 0;
1604 if (PageSwapCache(page
)) {
1607 entry
.val
= page_private(page
);
1608 si
= _swap_info_get(entry
);
1611 offset
= swp_offset(entry
);
1615 ci
= lock_cluster(si
, offset
);
1616 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1617 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
1618 _total_mapcount
+= mapcount
;
1620 swapcount
= swap_count(map
[offset
+ i
]);
1621 _total_swapcount
+= swapcount
;
1623 map_swapcount
= max(map_swapcount
, mapcount
+ swapcount
);
1626 if (PageDoubleMap(page
)) {
1628 _total_mapcount
-= HPAGE_PMD_NR
;
1630 mapcount
= compound_mapcount(page
);
1631 map_swapcount
+= mapcount
;
1632 _total_mapcount
+= mapcount
;
1634 *total_mapcount
= _total_mapcount
;
1635 if (total_swapcount
)
1636 *total_swapcount
= _total_swapcount
;
1638 return map_swapcount
;
1642 * We can write to an anon page without COW if there are no other references
1643 * to it. And as a side-effect, free up its swap: because the old content
1644 * on disk will never be read, and seeking back there to write new content
1645 * later would only waste time away from clustering.
1647 * NOTE: total_map_swapcount should not be relied upon by the caller if
1648 * reuse_swap_page() returns false, but it may be always overwritten
1649 * (see the other implementation for CONFIG_SWAP=n).
1651 bool reuse_swap_page(struct page
*page
, int *total_map_swapcount
)
1653 int count
, total_mapcount
, total_swapcount
;
1655 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1656 if (unlikely(PageKsm(page
)))
1658 count
= page_trans_huge_map_swapcount(page
, &total_mapcount
,
1660 if (total_map_swapcount
)
1661 *total_map_swapcount
= total_mapcount
+ total_swapcount
;
1662 if (count
== 1 && PageSwapCache(page
) &&
1663 (likely(!PageTransCompound(page
)) ||
1664 /* The remaining swap count will be freed soon */
1665 total_swapcount
== page_swapcount(page
))) {
1666 if (!PageWriteback(page
)) {
1667 page
= compound_head(page
);
1668 delete_from_swap_cache(page
);
1672 struct swap_info_struct
*p
;
1674 entry
.val
= page_private(page
);
1675 p
= swap_info_get(entry
);
1676 if (p
->flags
& SWP_STABLE_WRITES
) {
1677 spin_unlock(&p
->lock
);
1680 spin_unlock(&p
->lock
);
1688 * If swap is getting full, or if there are no more mappings of this page,
1689 * then try_to_free_swap is called to free its swap space.
1691 int try_to_free_swap(struct page
*page
)
1693 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1695 if (!PageSwapCache(page
))
1697 if (PageWriteback(page
))
1699 if (page_swapped(page
))
1703 * Once hibernation has begun to create its image of memory,
1704 * there's a danger that one of the calls to try_to_free_swap()
1705 * - most probably a call from __try_to_reclaim_swap() while
1706 * hibernation is allocating its own swap pages for the image,
1707 * but conceivably even a call from memory reclaim - will free
1708 * the swap from a page which has already been recorded in the
1709 * image as a clean swapcache page, and then reuse its swap for
1710 * another page of the image. On waking from hibernation, the
1711 * original page might be freed under memory pressure, then
1712 * later read back in from swap, now with the wrong data.
1714 * Hibernation suspends storage while it is writing the image
1715 * to disk so check that here.
1717 if (pm_suspended_storage())
1720 page
= compound_head(page
);
1721 delete_from_swap_cache(page
);
1727 * Free the swap entry like above, but also try to
1728 * free the page cache entry if it is the last user.
1730 int free_swap_and_cache(swp_entry_t entry
)
1732 struct swap_info_struct
*p
;
1733 unsigned char count
;
1735 if (non_swap_entry(entry
))
1738 p
= _swap_info_get(entry
);
1740 count
= __swap_entry_free(p
, entry
, 1);
1741 if (count
== SWAP_HAS_CACHE
&&
1742 !swap_page_trans_huge_swapped(p
, entry
))
1743 __try_to_reclaim_swap(p
, swp_offset(entry
),
1744 TTRS_UNMAPPED
| TTRS_FULL
);
1749 #ifdef CONFIG_HIBERNATION
1751 * Find the swap type that corresponds to given device (if any).
1753 * @offset - number of the PAGE_SIZE-sized block of the device, starting
1754 * from 0, in which the swap header is expected to be located.
1756 * This is needed for the suspend to disk (aka swsusp).
1758 int swap_type_of(dev_t device
, sector_t offset
, struct block_device
**bdev_p
)
1760 struct block_device
*bdev
= NULL
;
1764 bdev
= bdget(device
);
1766 spin_lock(&swap_lock
);
1767 for (type
= 0; type
< nr_swapfiles
; type
++) {
1768 struct swap_info_struct
*sis
= swap_info
[type
];
1770 if (!(sis
->flags
& SWP_WRITEOK
))
1775 *bdev_p
= bdgrab(sis
->bdev
);
1777 spin_unlock(&swap_lock
);
1780 if (bdev
== sis
->bdev
) {
1781 struct swap_extent
*se
= first_se(sis
);
1783 if (se
->start_block
== offset
) {
1785 *bdev_p
= bdgrab(sis
->bdev
);
1787 spin_unlock(&swap_lock
);
1793 spin_unlock(&swap_lock
);
1801 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
1802 * corresponding to given index in swap_info (swap type).
1804 sector_t
swapdev_block(int type
, pgoff_t offset
)
1806 struct block_device
*bdev
;
1807 struct swap_info_struct
*si
= swap_type_to_swap_info(type
);
1809 if (!si
|| !(si
->flags
& SWP_WRITEOK
))
1811 return map_swap_entry(swp_entry(type
, offset
), &bdev
);
1815 * Return either the total number of swap pages of given type, or the number
1816 * of free pages of that type (depending on @free)
1818 * This is needed for software suspend
1820 unsigned int count_swap_pages(int type
, int free
)
1824 spin_lock(&swap_lock
);
1825 if ((unsigned int)type
< nr_swapfiles
) {
1826 struct swap_info_struct
*sis
= swap_info
[type
];
1828 spin_lock(&sis
->lock
);
1829 if (sis
->flags
& SWP_WRITEOK
) {
1832 n
-= sis
->inuse_pages
;
1834 spin_unlock(&sis
->lock
);
1836 spin_unlock(&swap_lock
);
1839 #endif /* CONFIG_HIBERNATION */
1841 static inline int pte_same_as_swp(pte_t pte
, pte_t swp_pte
)
1843 return pte_same(pte_swp_clear_soft_dirty(pte
), swp_pte
);
1847 * No need to decide whether this PTE shares the swap entry with others,
1848 * just let do_wp_page work it out if a write is requested later - to
1849 * force COW, vm_page_prot omits write permission from any private vma.
1851 static int unuse_pte(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1852 unsigned long addr
, swp_entry_t entry
, struct page
*page
)
1854 struct page
*swapcache
;
1855 struct mem_cgroup
*memcg
;
1861 page
= ksm_might_need_to_copy(page
, vma
, addr
);
1862 if (unlikely(!page
))
1865 if (mem_cgroup_try_charge(page
, vma
->vm_mm
, GFP_KERNEL
,
1871 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
1872 if (unlikely(!pte_same_as_swp(*pte
, swp_entry_to_pte(entry
)))) {
1873 mem_cgroup_cancel_charge(page
, memcg
, false);
1878 dec_mm_counter(vma
->vm_mm
, MM_SWAPENTS
);
1879 inc_mm_counter(vma
->vm_mm
, MM_ANONPAGES
);
1881 set_pte_at(vma
->vm_mm
, addr
, pte
,
1882 pte_mkold(mk_pte(page
, vma
->vm_page_prot
)));
1883 if (page
== swapcache
) {
1884 page_add_anon_rmap(page
, vma
, addr
, false);
1885 mem_cgroup_commit_charge(page
, memcg
, true, false);
1886 } else { /* ksm created a completely new copy */
1887 page_add_new_anon_rmap(page
, vma
, addr
, false);
1888 mem_cgroup_commit_charge(page
, memcg
, false, false);
1889 lru_cache_add_active_or_unevictable(page
, vma
);
1893 * Move the page to the active list so it is not
1894 * immediately swapped out again after swapon.
1896 activate_page(page
);
1898 pte_unmap_unlock(pte
, ptl
);
1900 if (page
!= swapcache
) {
1907 static int unuse_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1908 unsigned long addr
, unsigned long end
,
1909 unsigned int type
, bool frontswap
,
1910 unsigned long *fs_pages_to_unuse
)
1915 struct swap_info_struct
*si
;
1916 unsigned long offset
;
1918 volatile unsigned char *swap_map
;
1920 si
= swap_info
[type
];
1921 pte
= pte_offset_map(pmd
, addr
);
1923 struct vm_fault vmf
;
1925 if (!is_swap_pte(*pte
))
1928 entry
= pte_to_swp_entry(*pte
);
1929 if (swp_type(entry
) != type
)
1932 offset
= swp_offset(entry
);
1933 if (frontswap
&& !frontswap_test(si
, offset
))
1937 swap_map
= &si
->swap_map
[offset
];
1938 page
= lookup_swap_cache(entry
, vma
, addr
);
1943 page
= swapin_readahead(entry
, GFP_HIGHUSER_MOVABLE
,
1947 if (*swap_map
== 0 || *swap_map
== SWAP_MAP_BAD
)
1953 wait_on_page_writeback(page
);
1954 ret
= unuse_pte(vma
, pmd
, addr
, entry
, page
);
1961 try_to_free_swap(page
);
1965 if (*fs_pages_to_unuse
&& !--(*fs_pages_to_unuse
)) {
1966 ret
= FRONTSWAP_PAGES_UNUSED
;
1970 pte
= pte_offset_map(pmd
, addr
);
1971 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1979 static inline int unuse_pmd_range(struct vm_area_struct
*vma
, pud_t
*pud
,
1980 unsigned long addr
, unsigned long end
,
1981 unsigned int type
, bool frontswap
,
1982 unsigned long *fs_pages_to_unuse
)
1988 pmd
= pmd_offset(pud
, addr
);
1991 next
= pmd_addr_end(addr
, end
);
1992 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
1994 ret
= unuse_pte_range(vma
, pmd
, addr
, next
, type
,
1995 frontswap
, fs_pages_to_unuse
);
1998 } while (pmd
++, addr
= next
, addr
!= end
);
2002 static inline int unuse_pud_range(struct vm_area_struct
*vma
, p4d_t
*p4d
,
2003 unsigned long addr
, unsigned long end
,
2004 unsigned int type
, bool frontswap
,
2005 unsigned long *fs_pages_to_unuse
)
2011 pud
= pud_offset(p4d
, addr
);
2013 next
= pud_addr_end(addr
, end
);
2014 if (pud_none_or_clear_bad(pud
))
2016 ret
= unuse_pmd_range(vma
, pud
, addr
, next
, type
,
2017 frontswap
, fs_pages_to_unuse
);
2020 } while (pud
++, addr
= next
, addr
!= end
);
2024 static inline int unuse_p4d_range(struct vm_area_struct
*vma
, pgd_t
*pgd
,
2025 unsigned long addr
, unsigned long end
,
2026 unsigned int type
, bool frontswap
,
2027 unsigned long *fs_pages_to_unuse
)
2033 p4d
= p4d_offset(pgd
, addr
);
2035 next
= p4d_addr_end(addr
, end
);
2036 if (p4d_none_or_clear_bad(p4d
))
2038 ret
= unuse_pud_range(vma
, p4d
, addr
, next
, type
,
2039 frontswap
, fs_pages_to_unuse
);
2042 } while (p4d
++, addr
= next
, addr
!= end
);
2046 static int unuse_vma(struct vm_area_struct
*vma
, unsigned int type
,
2047 bool frontswap
, unsigned long *fs_pages_to_unuse
)
2050 unsigned long addr
, end
, next
;
2053 addr
= vma
->vm_start
;
2056 pgd
= pgd_offset(vma
->vm_mm
, addr
);
2058 next
= pgd_addr_end(addr
, end
);
2059 if (pgd_none_or_clear_bad(pgd
))
2061 ret
= unuse_p4d_range(vma
, pgd
, addr
, next
, type
,
2062 frontswap
, fs_pages_to_unuse
);
2065 } while (pgd
++, addr
= next
, addr
!= end
);
2069 static int unuse_mm(struct mm_struct
*mm
, unsigned int type
,
2070 bool frontswap
, unsigned long *fs_pages_to_unuse
)
2072 struct vm_area_struct
*vma
;
2075 down_read(&mm
->mmap_sem
);
2076 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2077 if (vma
->anon_vma
) {
2078 ret
= unuse_vma(vma
, type
, frontswap
,
2085 up_read(&mm
->mmap_sem
);
2090 * Scan swap_map (or frontswap_map if frontswap parameter is true)
2091 * from current position to next entry still in use. Return 0
2092 * if there are no inuse entries after prev till end of the map.
2094 static unsigned int find_next_to_unuse(struct swap_info_struct
*si
,
2095 unsigned int prev
, bool frontswap
)
2098 unsigned char count
;
2101 * No need for swap_lock here: we're just looking
2102 * for whether an entry is in use, not modifying it; false
2103 * hits are okay, and sys_swapoff() has already prevented new
2104 * allocations from this area (while holding swap_lock).
2106 for (i
= prev
+ 1; i
< si
->max
; i
++) {
2107 count
= READ_ONCE(si
->swap_map
[i
]);
2108 if (count
&& swap_count(count
) != SWAP_MAP_BAD
)
2109 if (!frontswap
|| frontswap_test(si
, i
))
2111 if ((i
% LATENCY_LIMIT
) == 0)
2122 * If the boolean frontswap is true, only unuse pages_to_unuse pages;
2123 * pages_to_unuse==0 means all pages; ignored if frontswap is false
2125 int try_to_unuse(unsigned int type
, bool frontswap
,
2126 unsigned long pages_to_unuse
)
2128 struct mm_struct
*prev_mm
;
2129 struct mm_struct
*mm
;
2130 struct list_head
*p
;
2132 struct swap_info_struct
*si
= swap_info
[type
];
2137 if (!READ_ONCE(si
->inuse_pages
))
2144 retval
= shmem_unuse(type
, frontswap
, &pages_to_unuse
);
2151 spin_lock(&mmlist_lock
);
2152 p
= &init_mm
.mmlist
;
2153 while (READ_ONCE(si
->inuse_pages
) &&
2154 !signal_pending(current
) &&
2155 (p
= p
->next
) != &init_mm
.mmlist
) {
2157 mm
= list_entry(p
, struct mm_struct
, mmlist
);
2158 if (!mmget_not_zero(mm
))
2160 spin_unlock(&mmlist_lock
);
2163 retval
= unuse_mm(mm
, type
, frontswap
, &pages_to_unuse
);
2171 * Make sure that we aren't completely killing
2172 * interactive performance.
2175 spin_lock(&mmlist_lock
);
2177 spin_unlock(&mmlist_lock
);
2182 while (READ_ONCE(si
->inuse_pages
) &&
2183 !signal_pending(current
) &&
2184 (i
= find_next_to_unuse(si
, i
, frontswap
)) != 0) {
2186 entry
= swp_entry(type
, i
);
2187 page
= find_get_page(swap_address_space(entry
), i
);
2192 * It is conceivable that a racing task removed this page from
2193 * swap cache just before we acquired the page lock. The page
2194 * might even be back in swap cache on another swap area. But
2195 * that is okay, try_to_free_swap() only removes stale pages.
2198 wait_on_page_writeback(page
);
2199 try_to_free_swap(page
);
2204 * For frontswap, we just need to unuse pages_to_unuse, if
2205 * it was specified. Need not check frontswap again here as
2206 * we already zeroed out pages_to_unuse if not frontswap.
2208 if (pages_to_unuse
&& --pages_to_unuse
== 0)
2213 * Lets check again to see if there are still swap entries in the map.
2214 * If yes, we would need to do retry the unuse logic again.
2215 * Under global memory pressure, swap entries can be reinserted back
2216 * into process space after the mmlist loop above passes over them.
2218 * Limit the number of retries? No: when mmget_not_zero() above fails,
2219 * that mm is likely to be freeing swap from exit_mmap(), which proceeds
2220 * at its own independent pace; and even shmem_writepage() could have
2221 * been preempted after get_swap_page(), temporarily hiding that swap.
2222 * It's easy and robust (though cpu-intensive) just to keep retrying.
2224 if (READ_ONCE(si
->inuse_pages
)) {
2225 if (!signal_pending(current
))
2230 return (retval
== FRONTSWAP_PAGES_UNUSED
) ? 0 : retval
;
2234 * After a successful try_to_unuse, if no swap is now in use, we know
2235 * we can empty the mmlist. swap_lock must be held on entry and exit.
2236 * Note that mmlist_lock nests inside swap_lock, and an mm must be
2237 * added to the mmlist just after page_duplicate - before would be racy.
2239 static void drain_mmlist(void)
2241 struct list_head
*p
, *next
;
2244 for (type
= 0; type
< nr_swapfiles
; type
++)
2245 if (swap_info
[type
]->inuse_pages
)
2247 spin_lock(&mmlist_lock
);
2248 list_for_each_safe(p
, next
, &init_mm
.mmlist
)
2250 spin_unlock(&mmlist_lock
);
2254 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
2255 * corresponds to page offset for the specified swap entry.
2256 * Note that the type of this function is sector_t, but it returns page offset
2257 * into the bdev, not sector offset.
2259 static sector_t
map_swap_entry(swp_entry_t entry
, struct block_device
**bdev
)
2261 struct swap_info_struct
*sis
;
2262 struct swap_extent
*se
;
2265 sis
= swp_swap_info(entry
);
2268 offset
= swp_offset(entry
);
2269 se
= offset_to_swap_extent(sis
, offset
);
2270 return se
->start_block
+ (offset
- se
->start_page
);
2274 * Returns the page offset into bdev for the specified page's swap entry.
2276 sector_t
map_swap_page(struct page
*page
, struct block_device
**bdev
)
2279 entry
.val
= page_private(page
);
2280 return map_swap_entry(entry
, bdev
);
2284 * Free all of a swapdev's extent information
2286 static void destroy_swap_extents(struct swap_info_struct
*sis
)
2288 while (!RB_EMPTY_ROOT(&sis
->swap_extent_root
)) {
2289 struct rb_node
*rb
= sis
->swap_extent_root
.rb_node
;
2290 struct swap_extent
*se
= rb_entry(rb
, struct swap_extent
, rb_node
);
2292 rb_erase(rb
, &sis
->swap_extent_root
);
2296 if (sis
->flags
& SWP_ACTIVATED
) {
2297 struct file
*swap_file
= sis
->swap_file
;
2298 struct address_space
*mapping
= swap_file
->f_mapping
;
2300 sis
->flags
&= ~SWP_ACTIVATED
;
2301 if (mapping
->a_ops
->swap_deactivate
)
2302 mapping
->a_ops
->swap_deactivate(swap_file
);
2307 * Add a block range (and the corresponding page range) into this swapdev's
2310 * This function rather assumes that it is called in ascending page order.
2313 add_swap_extent(struct swap_info_struct
*sis
, unsigned long start_page
,
2314 unsigned long nr_pages
, sector_t start_block
)
2316 struct rb_node
**link
= &sis
->swap_extent_root
.rb_node
, *parent
= NULL
;
2317 struct swap_extent
*se
;
2318 struct swap_extent
*new_se
;
2321 * place the new node at the right most since the
2322 * function is called in ascending page order.
2326 link
= &parent
->rb_right
;
2330 se
= rb_entry(parent
, struct swap_extent
, rb_node
);
2331 BUG_ON(se
->start_page
+ se
->nr_pages
!= start_page
);
2332 if (se
->start_block
+ se
->nr_pages
== start_block
) {
2334 se
->nr_pages
+= nr_pages
;
2339 /* No merge, insert a new extent. */
2340 new_se
= kmalloc(sizeof(*se
), GFP_KERNEL
);
2343 new_se
->start_page
= start_page
;
2344 new_se
->nr_pages
= nr_pages
;
2345 new_se
->start_block
= start_block
;
2347 rb_link_node(&new_se
->rb_node
, parent
, link
);
2348 rb_insert_color(&new_se
->rb_node
, &sis
->swap_extent_root
);
2351 EXPORT_SYMBOL_GPL(add_swap_extent
);
2354 * A `swap extent' is a simple thing which maps a contiguous range of pages
2355 * onto a contiguous range of disk blocks. An ordered list of swap extents
2356 * is built at swapon time and is then used at swap_writepage/swap_readpage
2357 * time for locating where on disk a page belongs.
2359 * If the swapfile is an S_ISBLK block device, a single extent is installed.
2360 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
2361 * swap files identically.
2363 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
2364 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
2365 * swapfiles are handled *identically* after swapon time.
2367 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
2368 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
2369 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
2370 * requirements, they are simply tossed out - we will never use those blocks
2373 * For all swap devices we set S_SWAPFILE across the life of the swapon. This
2374 * prevents users from writing to the swap device, which will corrupt memory.
2376 * The amount of disk space which a single swap extent represents varies.
2377 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
2378 * extents in the list. To avoid much list walking, we cache the previous
2379 * search location in `curr_swap_extent', and start new searches from there.
2380 * This is extremely effective. The average number of iterations in
2381 * map_swap_page() has been measured at about 0.3 per page. - akpm.
2383 static int setup_swap_extents(struct swap_info_struct
*sis
, sector_t
*span
)
2385 struct file
*swap_file
= sis
->swap_file
;
2386 struct address_space
*mapping
= swap_file
->f_mapping
;
2387 struct inode
*inode
= mapping
->host
;
2390 if (S_ISBLK(inode
->i_mode
)) {
2391 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
2396 if (mapping
->a_ops
->swap_activate
) {
2397 ret
= mapping
->a_ops
->swap_activate(sis
, swap_file
, span
);
2399 sis
->flags
|= SWP_ACTIVATED
;
2401 sis
->flags
|= SWP_FS
;
2402 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
2408 return generic_swapfile_activate(sis
, swap_file
, span
);
2411 static int swap_node(struct swap_info_struct
*p
)
2413 struct block_device
*bdev
;
2418 bdev
= p
->swap_file
->f_inode
->i_sb
->s_bdev
;
2420 return bdev
? bdev
->bd_disk
->node_id
: NUMA_NO_NODE
;
2423 static void setup_swap_info(struct swap_info_struct
*p
, int prio
,
2424 unsigned char *swap_map
,
2425 struct swap_cluster_info
*cluster_info
)
2432 p
->prio
= --least_priority
;
2434 * the plist prio is negated because plist ordering is
2435 * low-to-high, while swap ordering is high-to-low
2437 p
->list
.prio
= -p
->prio
;
2440 p
->avail_lists
[i
].prio
= -p
->prio
;
2442 if (swap_node(p
) == i
)
2443 p
->avail_lists
[i
].prio
= 1;
2445 p
->avail_lists
[i
].prio
= -p
->prio
;
2448 p
->swap_map
= swap_map
;
2449 p
->cluster_info
= cluster_info
;
2452 static void _enable_swap_info(struct swap_info_struct
*p
)
2454 p
->flags
|= SWP_WRITEOK
| SWP_VALID
;
2455 atomic_long_add(p
->pages
, &nr_swap_pages
);
2456 total_swap_pages
+= p
->pages
;
2458 assert_spin_locked(&swap_lock
);
2460 * both lists are plists, and thus priority ordered.
2461 * swap_active_head needs to be priority ordered for swapoff(),
2462 * which on removal of any swap_info_struct with an auto-assigned
2463 * (i.e. negative) priority increments the auto-assigned priority
2464 * of any lower-priority swap_info_structs.
2465 * swap_avail_head needs to be priority ordered for get_swap_page(),
2466 * which allocates swap pages from the highest available priority
2469 plist_add(&p
->list
, &swap_active_head
);
2470 add_to_avail_list(p
);
2473 static void enable_swap_info(struct swap_info_struct
*p
, int prio
,
2474 unsigned char *swap_map
,
2475 struct swap_cluster_info
*cluster_info
,
2476 unsigned long *frontswap_map
)
2478 frontswap_init(p
->type
, frontswap_map
);
2479 spin_lock(&swap_lock
);
2480 spin_lock(&p
->lock
);
2481 setup_swap_info(p
, prio
, swap_map
, cluster_info
);
2482 spin_unlock(&p
->lock
);
2483 spin_unlock(&swap_lock
);
2485 * Guarantee swap_map, cluster_info, etc. fields are valid
2486 * between get/put_swap_device() if SWP_VALID bit is set
2489 spin_lock(&swap_lock
);
2490 spin_lock(&p
->lock
);
2491 _enable_swap_info(p
);
2492 spin_unlock(&p
->lock
);
2493 spin_unlock(&swap_lock
);
2496 static void reinsert_swap_info(struct swap_info_struct
*p
)
2498 spin_lock(&swap_lock
);
2499 spin_lock(&p
->lock
);
2500 setup_swap_info(p
, p
->prio
, p
->swap_map
, p
->cluster_info
);
2501 _enable_swap_info(p
);
2502 spin_unlock(&p
->lock
);
2503 spin_unlock(&swap_lock
);
2506 bool has_usable_swap(void)
2510 spin_lock(&swap_lock
);
2511 if (plist_head_empty(&swap_active_head
))
2513 spin_unlock(&swap_lock
);
2517 SYSCALL_DEFINE1(swapoff
, const char __user
*, specialfile
)
2519 struct swap_info_struct
*p
= NULL
;
2520 unsigned char *swap_map
;
2521 struct swap_cluster_info
*cluster_info
;
2522 unsigned long *frontswap_map
;
2523 struct file
*swap_file
, *victim
;
2524 struct address_space
*mapping
;
2525 struct inode
*inode
;
2526 struct filename
*pathname
;
2528 unsigned int old_block_size
;
2530 if (!capable(CAP_SYS_ADMIN
))
2533 BUG_ON(!current
->mm
);
2535 pathname
= getname(specialfile
);
2536 if (IS_ERR(pathname
))
2537 return PTR_ERR(pathname
);
2539 victim
= file_open_name(pathname
, O_RDWR
|O_LARGEFILE
, 0);
2540 err
= PTR_ERR(victim
);
2544 mapping
= victim
->f_mapping
;
2545 spin_lock(&swap_lock
);
2546 plist_for_each_entry(p
, &swap_active_head
, list
) {
2547 if (p
->flags
& SWP_WRITEOK
) {
2548 if (p
->swap_file
->f_mapping
== mapping
) {
2556 spin_unlock(&swap_lock
);
2559 if (!security_vm_enough_memory_mm(current
->mm
, p
->pages
))
2560 vm_unacct_memory(p
->pages
);
2563 spin_unlock(&swap_lock
);
2566 del_from_avail_list(p
);
2567 spin_lock(&p
->lock
);
2569 struct swap_info_struct
*si
= p
;
2572 plist_for_each_entry_continue(si
, &swap_active_head
, list
) {
2575 for_each_node(nid
) {
2576 if (si
->avail_lists
[nid
].prio
!= 1)
2577 si
->avail_lists
[nid
].prio
--;
2582 plist_del(&p
->list
, &swap_active_head
);
2583 atomic_long_sub(p
->pages
, &nr_swap_pages
);
2584 total_swap_pages
-= p
->pages
;
2585 p
->flags
&= ~SWP_WRITEOK
;
2586 spin_unlock(&p
->lock
);
2587 spin_unlock(&swap_lock
);
2589 disable_swap_slots_cache_lock();
2591 set_current_oom_origin();
2592 err
= try_to_unuse(p
->type
, false, 0); /* force unuse all pages */
2593 clear_current_oom_origin();
2596 /* re-insert swap space back into swap_list */
2597 reinsert_swap_info(p
);
2598 reenable_swap_slots_cache_unlock();
2602 reenable_swap_slots_cache_unlock();
2604 spin_lock(&swap_lock
);
2605 spin_lock(&p
->lock
);
2606 p
->flags
&= ~SWP_VALID
; /* mark swap device as invalid */
2607 spin_unlock(&p
->lock
);
2608 spin_unlock(&swap_lock
);
2610 * wait for swap operations protected by get/put_swap_device()
2615 flush_work(&p
->discard_work
);
2617 destroy_swap_extents(p
);
2618 if (p
->flags
& SWP_CONTINUED
)
2619 free_swap_count_continuations(p
);
2621 if (!p
->bdev
|| !blk_queue_nonrot(bdev_get_queue(p
->bdev
)))
2622 atomic_dec(&nr_rotate_swap
);
2624 mutex_lock(&swapon_mutex
);
2625 spin_lock(&swap_lock
);
2626 spin_lock(&p
->lock
);
2629 /* wait for anyone still in scan_swap_map */
2630 p
->highest_bit
= 0; /* cuts scans short */
2631 while (p
->flags
>= SWP_SCANNING
) {
2632 spin_unlock(&p
->lock
);
2633 spin_unlock(&swap_lock
);
2634 schedule_timeout_uninterruptible(1);
2635 spin_lock(&swap_lock
);
2636 spin_lock(&p
->lock
);
2639 swap_file
= p
->swap_file
;
2640 old_block_size
= p
->old_block_size
;
2641 p
->swap_file
= NULL
;
2643 swap_map
= p
->swap_map
;
2645 cluster_info
= p
->cluster_info
;
2646 p
->cluster_info
= NULL
;
2647 frontswap_map
= frontswap_map_get(p
);
2648 spin_unlock(&p
->lock
);
2649 spin_unlock(&swap_lock
);
2650 frontswap_invalidate_area(p
->type
);
2651 frontswap_map_set(p
, NULL
);
2652 mutex_unlock(&swapon_mutex
);
2653 free_percpu(p
->percpu_cluster
);
2654 p
->percpu_cluster
= NULL
;
2656 kvfree(cluster_info
);
2657 kvfree(frontswap_map
);
2658 /* Destroy swap account information */
2659 swap_cgroup_swapoff(p
->type
);
2660 exit_swap_address_space(p
->type
);
2662 inode
= mapping
->host
;
2663 if (S_ISBLK(inode
->i_mode
)) {
2664 struct block_device
*bdev
= I_BDEV(inode
);
2666 set_blocksize(bdev
, old_block_size
);
2667 blkdev_put(bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
2671 inode
->i_flags
&= ~S_SWAPFILE
;
2672 inode_unlock(inode
);
2673 filp_close(swap_file
, NULL
);
2676 * Clear the SWP_USED flag after all resources are freed so that swapon
2677 * can reuse this swap_info in alloc_swap_info() safely. It is ok to
2678 * not hold p->lock after we cleared its SWP_WRITEOK.
2680 spin_lock(&swap_lock
);
2682 spin_unlock(&swap_lock
);
2685 atomic_inc(&proc_poll_event
);
2686 wake_up_interruptible(&proc_poll_wait
);
2689 filp_close(victim
, NULL
);
2695 #ifdef CONFIG_PROC_FS
2696 static __poll_t
swaps_poll(struct file
*file
, poll_table
*wait
)
2698 struct seq_file
*seq
= file
->private_data
;
2700 poll_wait(file
, &proc_poll_wait
, wait
);
2702 if (seq
->poll_event
!= atomic_read(&proc_poll_event
)) {
2703 seq
->poll_event
= atomic_read(&proc_poll_event
);
2704 return EPOLLIN
| EPOLLRDNORM
| EPOLLERR
| EPOLLPRI
;
2707 return EPOLLIN
| EPOLLRDNORM
;
2711 static void *swap_start(struct seq_file
*swap
, loff_t
*pos
)
2713 struct swap_info_struct
*si
;
2717 mutex_lock(&swapon_mutex
);
2720 return SEQ_START_TOKEN
;
2722 for (type
= 0; (si
= swap_type_to_swap_info(type
)); type
++) {
2723 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
2732 static void *swap_next(struct seq_file
*swap
, void *v
, loff_t
*pos
)
2734 struct swap_info_struct
*si
= v
;
2737 if (v
== SEQ_START_TOKEN
)
2740 type
= si
->type
+ 1;
2743 for (; (si
= swap_type_to_swap_info(type
)); type
++) {
2744 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
2752 static void swap_stop(struct seq_file
*swap
, void *v
)
2754 mutex_unlock(&swapon_mutex
);
2757 static int swap_show(struct seq_file
*swap
, void *v
)
2759 struct swap_info_struct
*si
= v
;
2763 if (si
== SEQ_START_TOKEN
) {
2764 seq_puts(swap
,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
2768 file
= si
->swap_file
;
2769 len
= seq_file_path(swap
, file
, " \t\n\\");
2770 seq_printf(swap
, "%*s%s\t%u\t%u\t%d\n",
2771 len
< 40 ? 40 - len
: 1, " ",
2772 S_ISBLK(file_inode(file
)->i_mode
) ?
2773 "partition" : "file\t",
2774 si
->pages
<< (PAGE_SHIFT
- 10),
2775 si
->inuse_pages
<< (PAGE_SHIFT
- 10),
2780 static const struct seq_operations swaps_op
= {
2781 .start
= swap_start
,
2787 static int swaps_open(struct inode
*inode
, struct file
*file
)
2789 struct seq_file
*seq
;
2792 ret
= seq_open(file
, &swaps_op
);
2796 seq
= file
->private_data
;
2797 seq
->poll_event
= atomic_read(&proc_poll_event
);
2801 static const struct proc_ops swaps_proc_ops
= {
2802 .proc_flags
= PROC_ENTRY_PERMANENT
,
2803 .proc_open
= swaps_open
,
2804 .proc_read
= seq_read
,
2805 .proc_lseek
= seq_lseek
,
2806 .proc_release
= seq_release
,
2807 .proc_poll
= swaps_poll
,
2810 static int __init
procswaps_init(void)
2812 proc_create("swaps", 0, NULL
, &swaps_proc_ops
);
2815 __initcall(procswaps_init
);
2816 #endif /* CONFIG_PROC_FS */
2818 #ifdef MAX_SWAPFILES_CHECK
2819 static int __init
max_swapfiles_check(void)
2821 MAX_SWAPFILES_CHECK();
2824 late_initcall(max_swapfiles_check
);
2827 static struct swap_info_struct
*alloc_swap_info(void)
2829 struct swap_info_struct
*p
;
2833 p
= kvzalloc(struct_size(p
, avail_lists
, nr_node_ids
), GFP_KERNEL
);
2835 return ERR_PTR(-ENOMEM
);
2837 spin_lock(&swap_lock
);
2838 for (type
= 0; type
< nr_swapfiles
; type
++) {
2839 if (!(swap_info
[type
]->flags
& SWP_USED
))
2842 if (type
>= MAX_SWAPFILES
) {
2843 spin_unlock(&swap_lock
);
2845 return ERR_PTR(-EPERM
);
2847 if (type
>= nr_swapfiles
) {
2849 WRITE_ONCE(swap_info
[type
], p
);
2851 * Write swap_info[type] before nr_swapfiles, in case a
2852 * racing procfs swap_start() or swap_next() is reading them.
2853 * (We never shrink nr_swapfiles, we never free this entry.)
2856 WRITE_ONCE(nr_swapfiles
, nr_swapfiles
+ 1);
2859 p
= swap_info
[type
];
2861 * Do not memset this entry: a racing procfs swap_next()
2862 * would be relying on p->type to remain valid.
2865 p
->swap_extent_root
= RB_ROOT
;
2866 plist_node_init(&p
->list
, 0);
2868 plist_node_init(&p
->avail_lists
[i
], 0);
2869 p
->flags
= SWP_USED
;
2870 spin_unlock(&swap_lock
);
2871 spin_lock_init(&p
->lock
);
2872 spin_lock_init(&p
->cont_lock
);
2877 static int claim_swapfile(struct swap_info_struct
*p
, struct inode
*inode
)
2881 if (S_ISBLK(inode
->i_mode
)) {
2882 p
->bdev
= bdgrab(I_BDEV(inode
));
2883 error
= blkdev_get(p
->bdev
,
2884 FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
, p
);
2889 p
->old_block_size
= block_size(p
->bdev
);
2890 error
= set_blocksize(p
->bdev
, PAGE_SIZE
);
2894 * Zoned block devices contain zones that have a sequential
2895 * write only restriction. Hence zoned block devices are not
2896 * suitable for swapping. Disallow them here.
2898 if (blk_queue_is_zoned(p
->bdev
->bd_queue
))
2900 p
->flags
|= SWP_BLKDEV
;
2901 } else if (S_ISREG(inode
->i_mode
)) {
2902 p
->bdev
= inode
->i_sb
->s_bdev
;
2910 * Find out how many pages are allowed for a single swap device. There
2911 * are two limiting factors:
2912 * 1) the number of bits for the swap offset in the swp_entry_t type, and
2913 * 2) the number of bits in the swap pte, as defined by the different
2916 * In order to find the largest possible bit mask, a swap entry with
2917 * swap type 0 and swap offset ~0UL is created, encoded to a swap pte,
2918 * decoded to a swp_entry_t again, and finally the swap offset is
2921 * This will mask all the bits from the initial ~0UL mask that can't
2922 * be encoded in either the swp_entry_t or the architecture definition
2925 unsigned long generic_max_swapfile_size(void)
2927 return swp_offset(pte_to_swp_entry(
2928 swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
2931 /* Can be overridden by an architecture for additional checks. */
2932 __weak
unsigned long max_swapfile_size(void)
2934 return generic_max_swapfile_size();
2937 static unsigned long read_swap_header(struct swap_info_struct
*p
,
2938 union swap_header
*swap_header
,
2939 struct inode
*inode
)
2942 unsigned long maxpages
;
2943 unsigned long swapfilepages
;
2944 unsigned long last_page
;
2946 if (memcmp("SWAPSPACE2", swap_header
->magic
.magic
, 10)) {
2947 pr_err("Unable to find swap-space signature\n");
2951 /* swap partition endianess hack... */
2952 if (swab32(swap_header
->info
.version
) == 1) {
2953 swab32s(&swap_header
->info
.version
);
2954 swab32s(&swap_header
->info
.last_page
);
2955 swab32s(&swap_header
->info
.nr_badpages
);
2956 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
2958 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++)
2959 swab32s(&swap_header
->info
.badpages
[i
]);
2961 /* Check the swap header's sub-version */
2962 if (swap_header
->info
.version
!= 1) {
2963 pr_warn("Unable to handle swap header version %d\n",
2964 swap_header
->info
.version
);
2969 p
->cluster_next
= 1;
2972 maxpages
= max_swapfile_size();
2973 last_page
= swap_header
->info
.last_page
;
2975 pr_warn("Empty swap-file\n");
2978 if (last_page
> maxpages
) {
2979 pr_warn("Truncating oversized swap area, only using %luk out of %luk\n",
2980 maxpages
<< (PAGE_SHIFT
- 10),
2981 last_page
<< (PAGE_SHIFT
- 10));
2983 if (maxpages
> last_page
) {
2984 maxpages
= last_page
+ 1;
2985 /* p->max is an unsigned int: don't overflow it */
2986 if ((unsigned int)maxpages
== 0)
2987 maxpages
= UINT_MAX
;
2989 p
->highest_bit
= maxpages
- 1;
2993 swapfilepages
= i_size_read(inode
) >> PAGE_SHIFT
;
2994 if (swapfilepages
&& maxpages
> swapfilepages
) {
2995 pr_warn("Swap area shorter than signature indicates\n");
2998 if (swap_header
->info
.nr_badpages
&& S_ISREG(inode
->i_mode
))
3000 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
3006 #define SWAP_CLUSTER_INFO_COLS \
3007 DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
3008 #define SWAP_CLUSTER_SPACE_COLS \
3009 DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
3010 #define SWAP_CLUSTER_COLS \
3011 max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
3013 static int setup_swap_map_and_extents(struct swap_info_struct
*p
,
3014 union swap_header
*swap_header
,
3015 unsigned char *swap_map
,
3016 struct swap_cluster_info
*cluster_info
,
3017 unsigned long maxpages
,
3021 unsigned int nr_good_pages
;
3023 unsigned long nr_clusters
= DIV_ROUND_UP(maxpages
, SWAPFILE_CLUSTER
);
3024 unsigned long col
= p
->cluster_next
/ SWAPFILE_CLUSTER
% SWAP_CLUSTER_COLS
;
3025 unsigned long i
, idx
;
3027 nr_good_pages
= maxpages
- 1; /* omit header page */
3029 cluster_list_init(&p
->free_clusters
);
3030 cluster_list_init(&p
->discard_clusters
);
3032 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++) {
3033 unsigned int page_nr
= swap_header
->info
.badpages
[i
];
3034 if (page_nr
== 0 || page_nr
> swap_header
->info
.last_page
)
3036 if (page_nr
< maxpages
) {
3037 swap_map
[page_nr
] = SWAP_MAP_BAD
;
3040 * Haven't marked the cluster free yet, no list
3041 * operation involved
3043 inc_cluster_info_page(p
, cluster_info
, page_nr
);
3047 /* Haven't marked the cluster free yet, no list operation involved */
3048 for (i
= maxpages
; i
< round_up(maxpages
, SWAPFILE_CLUSTER
); i
++)
3049 inc_cluster_info_page(p
, cluster_info
, i
);
3051 if (nr_good_pages
) {
3052 swap_map
[0] = SWAP_MAP_BAD
;
3054 * Not mark the cluster free yet, no list
3055 * operation involved
3057 inc_cluster_info_page(p
, cluster_info
, 0);
3059 p
->pages
= nr_good_pages
;
3060 nr_extents
= setup_swap_extents(p
, span
);
3063 nr_good_pages
= p
->pages
;
3065 if (!nr_good_pages
) {
3066 pr_warn("Empty swap-file\n");
3075 * Reduce false cache line sharing between cluster_info and
3076 * sharing same address space.
3078 for (k
= 0; k
< SWAP_CLUSTER_COLS
; k
++) {
3079 j
= (k
+ col
) % SWAP_CLUSTER_COLS
;
3080 for (i
= 0; i
< DIV_ROUND_UP(nr_clusters
, SWAP_CLUSTER_COLS
); i
++) {
3081 idx
= i
* SWAP_CLUSTER_COLS
+ j
;
3082 if (idx
>= nr_clusters
)
3084 if (cluster_count(&cluster_info
[idx
]))
3086 cluster_set_flag(&cluster_info
[idx
], CLUSTER_FLAG_FREE
);
3087 cluster_list_add_tail(&p
->free_clusters
, cluster_info
,
3095 * Helper to sys_swapon determining if a given swap
3096 * backing device queue supports DISCARD operations.
3098 static bool swap_discardable(struct swap_info_struct
*si
)
3100 struct request_queue
*q
= bdev_get_queue(si
->bdev
);
3102 if (!q
|| !blk_queue_discard(q
))
3108 SYSCALL_DEFINE2(swapon
, const char __user
*, specialfile
, int, swap_flags
)
3110 struct swap_info_struct
*p
;
3111 struct filename
*name
;
3112 struct file
*swap_file
= NULL
;
3113 struct address_space
*mapping
;
3116 union swap_header
*swap_header
;
3119 unsigned long maxpages
;
3120 unsigned char *swap_map
= NULL
;
3121 struct swap_cluster_info
*cluster_info
= NULL
;
3122 unsigned long *frontswap_map
= NULL
;
3123 struct page
*page
= NULL
;
3124 struct inode
*inode
= NULL
;
3125 bool inced_nr_rotate_swap
= false;
3127 if (swap_flags
& ~SWAP_FLAGS_VALID
)
3130 if (!capable(CAP_SYS_ADMIN
))
3133 if (!swap_avail_heads
)
3136 p
= alloc_swap_info();
3140 INIT_WORK(&p
->discard_work
, swap_discard_work
);
3142 name
= getname(specialfile
);
3144 error
= PTR_ERR(name
);
3148 swap_file
= file_open_name(name
, O_RDWR
|O_LARGEFILE
, 0);
3149 if (IS_ERR(swap_file
)) {
3150 error
= PTR_ERR(swap_file
);
3155 p
->swap_file
= swap_file
;
3156 mapping
= swap_file
->f_mapping
;
3157 inode
= mapping
->host
;
3159 error
= claim_swapfile(p
, inode
);
3160 if (unlikely(error
))
3164 if (IS_SWAPFILE(inode
)) {
3166 goto bad_swap_unlock_inode
;
3170 * Read the swap header.
3172 if (!mapping
->a_ops
->readpage
) {
3174 goto bad_swap_unlock_inode
;
3176 page
= read_mapping_page(mapping
, 0, swap_file
);
3178 error
= PTR_ERR(page
);
3179 goto bad_swap_unlock_inode
;
3181 swap_header
= kmap(page
);
3183 maxpages
= read_swap_header(p
, swap_header
, inode
);
3184 if (unlikely(!maxpages
)) {
3186 goto bad_swap_unlock_inode
;
3189 /* OK, set up the swap map and apply the bad block list */
3190 swap_map
= vzalloc(maxpages
);
3193 goto bad_swap_unlock_inode
;
3196 if (bdi_cap_stable_pages_required(inode_to_bdi(inode
)))
3197 p
->flags
|= SWP_STABLE_WRITES
;
3199 if (bdi_cap_synchronous_io(inode_to_bdi(inode
)))
3200 p
->flags
|= SWP_SYNCHRONOUS_IO
;
3202 if (p
->bdev
&& blk_queue_nonrot(bdev_get_queue(p
->bdev
))) {
3204 unsigned long ci
, nr_cluster
;
3206 p
->flags
|= SWP_SOLIDSTATE
;
3208 * select a random position to start with to help wear leveling
3211 p
->cluster_next
= 1 + (prandom_u32() % p
->highest_bit
);
3212 nr_cluster
= DIV_ROUND_UP(maxpages
, SWAPFILE_CLUSTER
);
3214 cluster_info
= kvcalloc(nr_cluster
, sizeof(*cluster_info
),
3216 if (!cluster_info
) {
3218 goto bad_swap_unlock_inode
;
3221 for (ci
= 0; ci
< nr_cluster
; ci
++)
3222 spin_lock_init(&((cluster_info
+ ci
)->lock
));
3224 p
->percpu_cluster
= alloc_percpu(struct percpu_cluster
);
3225 if (!p
->percpu_cluster
) {
3227 goto bad_swap_unlock_inode
;
3229 for_each_possible_cpu(cpu
) {
3230 struct percpu_cluster
*cluster
;
3231 cluster
= per_cpu_ptr(p
->percpu_cluster
, cpu
);
3232 cluster_set_null(&cluster
->index
);
3235 atomic_inc(&nr_rotate_swap
);
3236 inced_nr_rotate_swap
= true;
3239 error
= swap_cgroup_swapon(p
->type
, maxpages
);
3241 goto bad_swap_unlock_inode
;
3243 nr_extents
= setup_swap_map_and_extents(p
, swap_header
, swap_map
,
3244 cluster_info
, maxpages
, &span
);
3245 if (unlikely(nr_extents
< 0)) {
3247 goto bad_swap_unlock_inode
;
3249 /* frontswap enabled? set up bit-per-page map for frontswap */
3250 if (IS_ENABLED(CONFIG_FRONTSWAP
))
3251 frontswap_map
= kvcalloc(BITS_TO_LONGS(maxpages
),
3255 if (p
->bdev
&&(swap_flags
& SWAP_FLAG_DISCARD
) && swap_discardable(p
)) {
3257 * When discard is enabled for swap with no particular
3258 * policy flagged, we set all swap discard flags here in
3259 * order to sustain backward compatibility with older
3260 * swapon(8) releases.
3262 p
->flags
|= (SWP_DISCARDABLE
| SWP_AREA_DISCARD
|
3266 * By flagging sys_swapon, a sysadmin can tell us to
3267 * either do single-time area discards only, or to just
3268 * perform discards for released swap page-clusters.
3269 * Now it's time to adjust the p->flags accordingly.
3271 if (swap_flags
& SWAP_FLAG_DISCARD_ONCE
)
3272 p
->flags
&= ~SWP_PAGE_DISCARD
;
3273 else if (swap_flags
& SWAP_FLAG_DISCARD_PAGES
)
3274 p
->flags
&= ~SWP_AREA_DISCARD
;
3276 /* issue a swapon-time discard if it's still required */
3277 if (p
->flags
& SWP_AREA_DISCARD
) {
3278 int err
= discard_swap(p
);
3280 pr_err("swapon: discard_swap(%p): %d\n",
3285 error
= init_swap_address_space(p
->type
, maxpages
);
3287 goto bad_swap_unlock_inode
;
3290 * Flush any pending IO and dirty mappings before we start using this
3293 inode
->i_flags
|= S_SWAPFILE
;
3294 error
= inode_drain_writes(inode
);
3296 inode
->i_flags
&= ~S_SWAPFILE
;
3297 goto bad_swap_unlock_inode
;
3300 mutex_lock(&swapon_mutex
);
3302 if (swap_flags
& SWAP_FLAG_PREFER
)
3304 (swap_flags
& SWAP_FLAG_PRIO_MASK
) >> SWAP_FLAG_PRIO_SHIFT
;
3305 enable_swap_info(p
, prio
, swap_map
, cluster_info
, frontswap_map
);
3307 pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
3308 p
->pages
<<(PAGE_SHIFT
-10), name
->name
, p
->prio
,
3309 nr_extents
, (unsigned long long)span
<<(PAGE_SHIFT
-10),
3310 (p
->flags
& SWP_SOLIDSTATE
) ? "SS" : "",
3311 (p
->flags
& SWP_DISCARDABLE
) ? "D" : "",
3312 (p
->flags
& SWP_AREA_DISCARD
) ? "s" : "",
3313 (p
->flags
& SWP_PAGE_DISCARD
) ? "c" : "",
3314 (frontswap_map
) ? "FS" : "");
3316 mutex_unlock(&swapon_mutex
);
3317 atomic_inc(&proc_poll_event
);
3318 wake_up_interruptible(&proc_poll_wait
);
3322 bad_swap_unlock_inode
:
3323 inode_unlock(inode
);
3325 free_percpu(p
->percpu_cluster
);
3326 p
->percpu_cluster
= NULL
;
3327 if (inode
&& S_ISBLK(inode
->i_mode
) && p
->bdev
) {
3328 set_blocksize(p
->bdev
, p
->old_block_size
);
3329 blkdev_put(p
->bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
3332 destroy_swap_extents(p
);
3333 swap_cgroup_swapoff(p
->type
);
3334 spin_lock(&swap_lock
);
3335 p
->swap_file
= NULL
;
3337 spin_unlock(&swap_lock
);
3339 kvfree(cluster_info
);
3340 kvfree(frontswap_map
);
3341 if (inced_nr_rotate_swap
)
3342 atomic_dec(&nr_rotate_swap
);
3344 filp_close(swap_file
, NULL
);
3346 if (page
&& !IS_ERR(page
)) {
3353 inode_unlock(inode
);
3355 enable_swap_slots_cache();
3359 void si_swapinfo(struct sysinfo
*val
)
3362 unsigned long nr_to_be_unused
= 0;
3364 spin_lock(&swap_lock
);
3365 for (type
= 0; type
< nr_swapfiles
; type
++) {
3366 struct swap_info_struct
*si
= swap_info
[type
];
3368 if ((si
->flags
& SWP_USED
) && !(si
->flags
& SWP_WRITEOK
))
3369 nr_to_be_unused
+= si
->inuse_pages
;
3371 val
->freeswap
= atomic_long_read(&nr_swap_pages
) + nr_to_be_unused
;
3372 val
->totalswap
= total_swap_pages
+ nr_to_be_unused
;
3373 spin_unlock(&swap_lock
);
3377 * Verify that a swap entry is valid and increment its swap map count.
3379 * Returns error code in following case.
3381 * - swp_entry is invalid -> EINVAL
3382 * - swp_entry is migration entry -> EINVAL
3383 * - swap-cache reference is requested but there is already one. -> EEXIST
3384 * - swap-cache reference is requested but the entry is not used. -> ENOENT
3385 * - swap-mapped reference requested but needs continued swap count. -> ENOMEM
3387 static int __swap_duplicate(swp_entry_t entry
, unsigned char usage
)
3389 struct swap_info_struct
*p
;
3390 struct swap_cluster_info
*ci
;
3391 unsigned long offset
;
3392 unsigned char count
;
3393 unsigned char has_cache
;
3396 p
= get_swap_device(entry
);
3400 offset
= swp_offset(entry
);
3401 ci
= lock_cluster_or_swap_info(p
, offset
);
3403 count
= p
->swap_map
[offset
];
3406 * swapin_readahead() doesn't check if a swap entry is valid, so the
3407 * swap entry could be SWAP_MAP_BAD. Check here with lock held.
3409 if (unlikely(swap_count(count
) == SWAP_MAP_BAD
)) {
3414 has_cache
= count
& SWAP_HAS_CACHE
;
3415 count
&= ~SWAP_HAS_CACHE
;
3418 if (usage
== SWAP_HAS_CACHE
) {
3420 /* set SWAP_HAS_CACHE if there is no cache and entry is used */
3421 if (!has_cache
&& count
)
3422 has_cache
= SWAP_HAS_CACHE
;
3423 else if (has_cache
) /* someone else added cache */
3425 else /* no users remaining */
3428 } else if (count
|| has_cache
) {
3430 if ((count
& ~COUNT_CONTINUED
) < SWAP_MAP_MAX
)
3432 else if ((count
& ~COUNT_CONTINUED
) > SWAP_MAP_MAX
)
3434 else if (swap_count_continued(p
, offset
, count
))
3435 count
= COUNT_CONTINUED
;
3439 err
= -ENOENT
; /* unused swap entry */
3441 p
->swap_map
[offset
] = count
| has_cache
;
3444 unlock_cluster_or_swap_info(p
, ci
);
3452 * Help swapoff by noting that swap entry belongs to shmem/tmpfs
3453 * (in which case its reference count is never incremented).
3455 void swap_shmem_alloc(swp_entry_t entry
)
3457 __swap_duplicate(entry
, SWAP_MAP_SHMEM
);
3461 * Increase reference count of swap entry by 1.
3462 * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
3463 * but could not be atomically allocated. Returns 0, just as if it succeeded,
3464 * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
3465 * might occur if a page table entry has got corrupted.
3467 int swap_duplicate(swp_entry_t entry
)
3471 while (!err
&& __swap_duplicate(entry
, 1) == -ENOMEM
)
3472 err
= add_swap_count_continuation(entry
, GFP_ATOMIC
);
3477 * @entry: swap entry for which we allocate swap cache.
3479 * Called when allocating swap cache for existing swap entry,
3480 * This can return error codes. Returns 0 at success.
3481 * -EEXIST means there is a swap cache.
3482 * Note: return code is different from swap_duplicate().
3484 int swapcache_prepare(swp_entry_t entry
)
3486 return __swap_duplicate(entry
, SWAP_HAS_CACHE
);
3489 struct swap_info_struct
*swp_swap_info(swp_entry_t entry
)
3491 return swap_type_to_swap_info(swp_type(entry
));
3494 struct swap_info_struct
*page_swap_info(struct page
*page
)
3496 swp_entry_t entry
= { .val
= page_private(page
) };
3497 return swp_swap_info(entry
);
3501 * out-of-line __page_file_ methods to avoid include hell.
3503 struct address_space
*__page_file_mapping(struct page
*page
)
3505 return page_swap_info(page
)->swap_file
->f_mapping
;
3507 EXPORT_SYMBOL_GPL(__page_file_mapping
);
3509 pgoff_t
__page_file_index(struct page
*page
)
3511 swp_entry_t swap
= { .val
= page_private(page
) };
3512 return swp_offset(swap
);
3514 EXPORT_SYMBOL_GPL(__page_file_index
);
3517 * add_swap_count_continuation - called when a swap count is duplicated
3518 * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
3519 * page of the original vmalloc'ed swap_map, to hold the continuation count
3520 * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called
3521 * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
3523 * These continuation pages are seldom referenced: the common paths all work
3524 * on the original swap_map, only referring to a continuation page when the
3525 * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
3527 * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
3528 * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
3529 * can be called after dropping locks.
3531 int add_swap_count_continuation(swp_entry_t entry
, gfp_t gfp_mask
)
3533 struct swap_info_struct
*si
;
3534 struct swap_cluster_info
*ci
;
3537 struct page
*list_page
;
3539 unsigned char count
;
3543 * When debugging, it's easier to use __GFP_ZERO here; but it's better
3544 * for latency not to zero a page while GFP_ATOMIC and holding locks.
3546 page
= alloc_page(gfp_mask
| __GFP_HIGHMEM
);
3548 si
= get_swap_device(entry
);
3551 * An acceptable race has occurred since the failing
3552 * __swap_duplicate(): the swap device may be swapoff
3556 spin_lock(&si
->lock
);
3558 offset
= swp_offset(entry
);
3560 ci
= lock_cluster(si
, offset
);
3562 count
= si
->swap_map
[offset
] & ~SWAP_HAS_CACHE
;
3564 if ((count
& ~COUNT_CONTINUED
) != SWAP_MAP_MAX
) {
3566 * The higher the swap count, the more likely it is that tasks
3567 * will race to add swap count continuation: we need to avoid
3568 * over-provisioning.
3579 * We are fortunate that although vmalloc_to_page uses pte_offset_map,
3580 * no architecture is using highmem pages for kernel page tables: so it
3581 * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps.
3583 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3584 offset
&= ~PAGE_MASK
;
3586 spin_lock(&si
->cont_lock
);
3588 * Page allocation does not initialize the page's lru field,
3589 * but it does always reset its private field.
3591 if (!page_private(head
)) {
3592 BUG_ON(count
& COUNT_CONTINUED
);
3593 INIT_LIST_HEAD(&head
->lru
);
3594 set_page_private(head
, SWP_CONTINUED
);
3595 si
->flags
|= SWP_CONTINUED
;
3598 list_for_each_entry(list_page
, &head
->lru
, lru
) {
3602 * If the previous map said no continuation, but we've found
3603 * a continuation page, free our allocation and use this one.
3605 if (!(count
& COUNT_CONTINUED
))
3606 goto out_unlock_cont
;
3608 map
= kmap_atomic(list_page
) + offset
;
3613 * If this continuation count now has some space in it,
3614 * free our allocation and use this one.
3616 if ((count
& ~COUNT_CONTINUED
) != SWAP_CONT_MAX
)
3617 goto out_unlock_cont
;
3620 list_add_tail(&page
->lru
, &head
->lru
);
3621 page
= NULL
; /* now it's attached, don't free it */
3623 spin_unlock(&si
->cont_lock
);
3626 spin_unlock(&si
->lock
);
3627 put_swap_device(si
);
3635 * swap_count_continued - when the original swap_map count is incremented
3636 * from SWAP_MAP_MAX, check if there is already a continuation page to carry
3637 * into, carry if so, or else fail until a new continuation page is allocated;
3638 * when the original swap_map count is decremented from 0 with continuation,
3639 * borrow from the continuation and report whether it still holds more.
3640 * Called while __swap_duplicate() or swap_entry_free() holds swap or cluster
3643 static bool swap_count_continued(struct swap_info_struct
*si
,
3644 pgoff_t offset
, unsigned char count
)
3651 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3652 if (page_private(head
) != SWP_CONTINUED
) {
3653 BUG_ON(count
& COUNT_CONTINUED
);
3654 return false; /* need to add count continuation */
3657 spin_lock(&si
->cont_lock
);
3658 offset
&= ~PAGE_MASK
;
3659 page
= list_next_entry(head
, lru
);
3660 map
= kmap_atomic(page
) + offset
;
3662 if (count
== SWAP_MAP_MAX
) /* initial increment from swap_map */
3663 goto init_map
; /* jump over SWAP_CONT_MAX checks */
3665 if (count
== (SWAP_MAP_MAX
| COUNT_CONTINUED
)) { /* incrementing */
3667 * Think of how you add 1 to 999
3669 while (*map
== (SWAP_CONT_MAX
| COUNT_CONTINUED
)) {
3671 page
= list_next_entry(page
, lru
);
3672 BUG_ON(page
== head
);
3673 map
= kmap_atomic(page
) + offset
;
3675 if (*map
== SWAP_CONT_MAX
) {
3677 page
= list_next_entry(page
, lru
);
3679 ret
= false; /* add count continuation */
3682 map
= kmap_atomic(page
) + offset
;
3683 init_map
: *map
= 0; /* we didn't zero the page */
3687 while ((page
= list_prev_entry(page
, lru
)) != head
) {
3688 map
= kmap_atomic(page
) + offset
;
3689 *map
= COUNT_CONTINUED
;
3692 ret
= true; /* incremented */
3694 } else { /* decrementing */
3696 * Think of how you subtract 1 from 1000
3698 BUG_ON(count
!= COUNT_CONTINUED
);
3699 while (*map
== COUNT_CONTINUED
) {
3701 page
= list_next_entry(page
, lru
);
3702 BUG_ON(page
== head
);
3703 map
= kmap_atomic(page
) + offset
;
3710 while ((page
= list_prev_entry(page
, lru
)) != head
) {
3711 map
= kmap_atomic(page
) + offset
;
3712 *map
= SWAP_CONT_MAX
| count
;
3713 count
= COUNT_CONTINUED
;
3716 ret
= count
== COUNT_CONTINUED
;
3719 spin_unlock(&si
->cont_lock
);
3724 * free_swap_count_continuations - swapoff free all the continuation pages
3725 * appended to the swap_map, after swap_map is quiesced, before vfree'ing it.
3727 static void free_swap_count_continuations(struct swap_info_struct
*si
)
3731 for (offset
= 0; offset
< si
->max
; offset
+= PAGE_SIZE
) {
3733 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3734 if (page_private(head
)) {
3735 struct page
*page
, *next
;
3737 list_for_each_entry_safe(page
, next
, &head
->lru
, lru
) {
3738 list_del(&page
->lru
);
3745 #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
3746 void mem_cgroup_throttle_swaprate(struct mem_cgroup
*memcg
, int node
,
3749 struct swap_info_struct
*si
, *next
;
3750 if (!(gfp_mask
& __GFP_IO
) || !memcg
)
3753 if (!blk_cgroup_congested())
3757 * We've already scheduled a throttle, avoid taking the global swap
3760 if (current
->throttle_queue
)
3763 spin_lock(&swap_avail_lock
);
3764 plist_for_each_entry_safe(si
, next
, &swap_avail_heads
[node
],
3765 avail_lists
[node
]) {
3767 blkcg_schedule_throttle(bdev_get_queue(si
->bdev
),
3772 spin_unlock(&swap_avail_lock
);
3776 static int __init
swapfile_init(void)
3780 swap_avail_heads
= kmalloc_array(nr_node_ids
, sizeof(struct plist_head
),
3782 if (!swap_avail_heads
) {
3783 pr_emerg("Not enough memory for swap heads, swap is disabled\n");
3788 plist_head_init(&swap_avail_heads
[nid
]);
3792 subsys_initcall(swapfile_init
);