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
;
737 * We try to cluster swap pages by allocating them sequentially
738 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
739 * way, however, we resort to first-free allocation, starting
740 * a new cluster. This prevents us from scattering swap pages
741 * all over the entire swap partition, so that we reduce
742 * overall disk seek times between swap pages. -- sct
743 * But we do now try to find an empty cluster. -Andrea
744 * And we let swap pages go all over an SSD partition. Hugh
747 si
->flags
+= SWP_SCANNING
;
748 scan_base
= offset
= si
->cluster_next
;
751 if (si
->cluster_info
) {
752 if (!scan_swap_map_try_ssd_cluster(si
, &offset
, &scan_base
))
754 } else if (unlikely(!si
->cluster_nr
--)) {
755 if (si
->pages
- si
->inuse_pages
< SWAPFILE_CLUSTER
) {
756 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
760 spin_unlock(&si
->lock
);
763 * If seek is expensive, start searching for new cluster from
764 * start of partition, to minimize the span of allocated swap.
765 * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info
766 * case, just handled by scan_swap_map_try_ssd_cluster() above.
768 scan_base
= offset
= si
->lowest_bit
;
769 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
- 1;
771 /* Locate the first empty (unaligned) cluster */
772 for (; last_in_cluster
<= si
->highest_bit
; offset
++) {
773 if (si
->swap_map
[offset
])
774 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
;
775 else if (offset
== last_in_cluster
) {
776 spin_lock(&si
->lock
);
777 offset
-= SWAPFILE_CLUSTER
- 1;
778 si
->cluster_next
= offset
;
779 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
782 if (unlikely(--latency_ration
< 0)) {
784 latency_ration
= LATENCY_LIMIT
;
789 spin_lock(&si
->lock
);
790 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
794 if (si
->cluster_info
) {
795 while (scan_swap_map_ssd_cluster_conflict(si
, offset
)) {
796 /* take a break if we already got some slots */
799 if (!scan_swap_map_try_ssd_cluster(si
, &offset
,
804 if (!(si
->flags
& SWP_WRITEOK
))
806 if (!si
->highest_bit
)
808 if (offset
> si
->highest_bit
)
809 scan_base
= offset
= si
->lowest_bit
;
811 ci
= lock_cluster(si
, offset
);
812 /* reuse swap entry of cache-only swap if not busy. */
813 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
816 spin_unlock(&si
->lock
);
817 swap_was_freed
= __try_to_reclaim_swap(si
, offset
, TTRS_ANYWAY
);
818 spin_lock(&si
->lock
);
819 /* entry was freed successfully, try to use this again */
822 goto scan
; /* check next one */
825 if (si
->swap_map
[offset
]) {
832 si
->swap_map
[offset
] = usage
;
833 inc_cluster_info_page(si
, si
->cluster_info
, offset
);
836 swap_range_alloc(si
, offset
, 1);
837 si
->cluster_next
= offset
+ 1;
838 slots
[n_ret
++] = swp_entry(si
->type
, offset
);
840 /* got enough slots or reach max slots? */
841 if ((n_ret
== nr
) || (offset
>= si
->highest_bit
))
844 /* search for next available slot */
846 /* time to take a break? */
847 if (unlikely(--latency_ration
< 0)) {
850 spin_unlock(&si
->lock
);
852 spin_lock(&si
->lock
);
853 latency_ration
= LATENCY_LIMIT
;
856 /* try to get more slots in cluster */
857 if (si
->cluster_info
) {
858 if (scan_swap_map_try_ssd_cluster(si
, &offset
, &scan_base
))
860 } else if (si
->cluster_nr
&& !si
->swap_map
[++offset
]) {
861 /* non-ssd case, still more slots in cluster? */
867 si
->flags
-= SWP_SCANNING
;
871 spin_unlock(&si
->lock
);
872 while (++offset
<= si
->highest_bit
) {
873 if (!si
->swap_map
[offset
]) {
874 spin_lock(&si
->lock
);
877 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
878 spin_lock(&si
->lock
);
881 if (unlikely(--latency_ration
< 0)) {
883 latency_ration
= LATENCY_LIMIT
;
886 offset
= si
->lowest_bit
;
887 while (offset
< scan_base
) {
888 if (!si
->swap_map
[offset
]) {
889 spin_lock(&si
->lock
);
892 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
893 spin_lock(&si
->lock
);
896 if (unlikely(--latency_ration
< 0)) {
898 latency_ration
= LATENCY_LIMIT
;
902 spin_lock(&si
->lock
);
905 si
->flags
-= SWP_SCANNING
;
909 static int swap_alloc_cluster(struct swap_info_struct
*si
, swp_entry_t
*slot
)
912 struct swap_cluster_info
*ci
;
913 unsigned long offset
, i
;
917 * Should not even be attempting cluster allocations when huge
918 * page swap is disabled. Warn and fail the allocation.
920 if (!IS_ENABLED(CONFIG_THP_SWAP
)) {
925 if (cluster_list_empty(&si
->free_clusters
))
928 idx
= cluster_list_first(&si
->free_clusters
);
929 offset
= idx
* SWAPFILE_CLUSTER
;
930 ci
= lock_cluster(si
, offset
);
931 alloc_cluster(si
, idx
);
932 cluster_set_count_flag(ci
, SWAPFILE_CLUSTER
, CLUSTER_FLAG_HUGE
);
934 map
= si
->swap_map
+ offset
;
935 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++)
936 map
[i
] = SWAP_HAS_CACHE
;
938 swap_range_alloc(si
, offset
, SWAPFILE_CLUSTER
);
939 *slot
= swp_entry(si
->type
, offset
);
944 static void swap_free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
946 unsigned long offset
= idx
* SWAPFILE_CLUSTER
;
947 struct swap_cluster_info
*ci
;
949 ci
= lock_cluster(si
, offset
);
950 memset(si
->swap_map
+ offset
, 0, SWAPFILE_CLUSTER
);
951 cluster_set_count_flag(ci
, 0, 0);
952 free_cluster(si
, idx
);
954 swap_range_free(si
, offset
, SWAPFILE_CLUSTER
);
957 static unsigned long scan_swap_map(struct swap_info_struct
*si
,
963 n_ret
= scan_swap_map_slots(si
, usage
, 1, &entry
);
966 return swp_offset(entry
);
972 int get_swap_pages(int n_goal
, swp_entry_t swp_entries
[], int entry_size
)
974 unsigned long size
= swap_entry_size(entry_size
);
975 struct swap_info_struct
*si
, *next
;
980 /* Only single cluster request supported */
981 WARN_ON_ONCE(n_goal
> 1 && size
== SWAPFILE_CLUSTER
);
983 avail_pgs
= atomic_long_read(&nr_swap_pages
) / size
;
987 n_goal
= min3((long)n_goal
, (long)SWAP_BATCH
, avail_pgs
);
989 atomic_long_sub(n_goal
* size
, &nr_swap_pages
);
991 spin_lock(&swap_avail_lock
);
994 node
= numa_node_id();
995 plist_for_each_entry_safe(si
, next
, &swap_avail_heads
[node
], avail_lists
[node
]) {
996 /* requeue si to after same-priority siblings */
997 plist_requeue(&si
->avail_lists
[node
], &swap_avail_heads
[node
]);
998 spin_unlock(&swap_avail_lock
);
999 spin_lock(&si
->lock
);
1000 if (!si
->highest_bit
|| !(si
->flags
& SWP_WRITEOK
)) {
1001 spin_lock(&swap_avail_lock
);
1002 if (plist_node_empty(&si
->avail_lists
[node
])) {
1003 spin_unlock(&si
->lock
);
1006 WARN(!si
->highest_bit
,
1007 "swap_info %d in list but !highest_bit\n",
1009 WARN(!(si
->flags
& SWP_WRITEOK
),
1010 "swap_info %d in list but !SWP_WRITEOK\n",
1012 __del_from_avail_list(si
);
1013 spin_unlock(&si
->lock
);
1016 if (size
== SWAPFILE_CLUSTER
) {
1017 if (!(si
->flags
& SWP_FS
))
1018 n_ret
= swap_alloc_cluster(si
, swp_entries
);
1020 n_ret
= scan_swap_map_slots(si
, SWAP_HAS_CACHE
,
1021 n_goal
, swp_entries
);
1022 spin_unlock(&si
->lock
);
1023 if (n_ret
|| size
== SWAPFILE_CLUSTER
)
1025 pr_debug("scan_swap_map of si %d failed to find offset\n",
1028 spin_lock(&swap_avail_lock
);
1031 * if we got here, it's likely that si was almost full before,
1032 * and since scan_swap_map() can drop the si->lock, multiple
1033 * callers probably all tried to get a page from the same si
1034 * and it filled up before we could get one; or, the si filled
1035 * up between us dropping swap_avail_lock and taking si->lock.
1036 * Since we dropped the swap_avail_lock, the swap_avail_head
1037 * list may have been modified; so if next is still in the
1038 * swap_avail_head list then try it, otherwise start over
1039 * if we have not gotten any slots.
1041 if (plist_node_empty(&next
->avail_lists
[node
]))
1045 spin_unlock(&swap_avail_lock
);
1049 atomic_long_add((long)(n_goal
- n_ret
) * size
,
1055 /* The only caller of this function is now suspend routine */
1056 swp_entry_t
get_swap_page_of_type(int type
)
1058 struct swap_info_struct
*si
= swap_type_to_swap_info(type
);
1064 spin_lock(&si
->lock
);
1065 if (si
->flags
& SWP_WRITEOK
) {
1066 atomic_long_dec(&nr_swap_pages
);
1067 /* This is called for allocating swap entry, not cache */
1068 offset
= scan_swap_map(si
, 1);
1070 spin_unlock(&si
->lock
);
1071 return swp_entry(type
, offset
);
1073 atomic_long_inc(&nr_swap_pages
);
1075 spin_unlock(&si
->lock
);
1077 return (swp_entry_t
) {0};
1080 static struct swap_info_struct
*__swap_info_get(swp_entry_t entry
)
1082 struct swap_info_struct
*p
;
1083 unsigned long offset
;
1087 p
= swp_swap_info(entry
);
1090 if (!(p
->flags
& SWP_USED
))
1092 offset
= swp_offset(entry
);
1093 if (offset
>= p
->max
)
1098 pr_err("swap_info_get: %s%08lx\n", Bad_offset
, entry
.val
);
1101 pr_err("swap_info_get: %s%08lx\n", Unused_file
, entry
.val
);
1104 pr_err("swap_info_get: %s%08lx\n", Bad_file
, entry
.val
);
1109 static struct swap_info_struct
*_swap_info_get(swp_entry_t entry
)
1111 struct swap_info_struct
*p
;
1113 p
= __swap_info_get(entry
);
1116 if (!p
->swap_map
[swp_offset(entry
)])
1121 pr_err("swap_info_get: %s%08lx\n", Unused_offset
, entry
.val
);
1127 static struct swap_info_struct
*swap_info_get(swp_entry_t entry
)
1129 struct swap_info_struct
*p
;
1131 p
= _swap_info_get(entry
);
1133 spin_lock(&p
->lock
);
1137 static struct swap_info_struct
*swap_info_get_cont(swp_entry_t entry
,
1138 struct swap_info_struct
*q
)
1140 struct swap_info_struct
*p
;
1142 p
= _swap_info_get(entry
);
1146 spin_unlock(&q
->lock
);
1148 spin_lock(&p
->lock
);
1153 static unsigned char __swap_entry_free_locked(struct swap_info_struct
*p
,
1154 unsigned long offset
,
1155 unsigned char usage
)
1157 unsigned char count
;
1158 unsigned char has_cache
;
1160 count
= p
->swap_map
[offset
];
1162 has_cache
= count
& SWAP_HAS_CACHE
;
1163 count
&= ~SWAP_HAS_CACHE
;
1165 if (usage
== SWAP_HAS_CACHE
) {
1166 VM_BUG_ON(!has_cache
);
1168 } else if (count
== SWAP_MAP_SHMEM
) {
1170 * Or we could insist on shmem.c using a special
1171 * swap_shmem_free() and free_shmem_swap_and_cache()...
1174 } else if ((count
& ~COUNT_CONTINUED
) <= SWAP_MAP_MAX
) {
1175 if (count
== COUNT_CONTINUED
) {
1176 if (swap_count_continued(p
, offset
, count
))
1177 count
= SWAP_MAP_MAX
| COUNT_CONTINUED
;
1179 count
= SWAP_MAP_MAX
;
1184 usage
= count
| has_cache
;
1185 p
->swap_map
[offset
] = usage
? : SWAP_HAS_CACHE
;
1191 * Check whether swap entry is valid in the swap device. If so,
1192 * return pointer to swap_info_struct, and keep the swap entry valid
1193 * via preventing the swap device from being swapoff, until
1194 * put_swap_device() is called. Otherwise return NULL.
1196 * The entirety of the RCU read critical section must come before the
1197 * return from or after the call to synchronize_rcu() in
1198 * enable_swap_info() or swapoff(). So if "si->flags & SWP_VALID" is
1199 * true, the si->map, si->cluster_info, etc. must be valid in the
1202 * Notice that swapoff or swapoff+swapon can still happen before the
1203 * rcu_read_lock() in get_swap_device() or after the rcu_read_unlock()
1204 * in put_swap_device() if there isn't any other way to prevent
1205 * swapoff, such as page lock, page table lock, etc. The caller must
1206 * be prepared for that. For example, the following situation is
1211 * ... swapoff+swapon
1212 * __read_swap_cache_async()
1213 * swapcache_prepare()
1214 * __swap_duplicate()
1216 * // verify PTE not changed
1218 * In __swap_duplicate(), the swap_map need to be checked before
1219 * changing partly because the specified swap entry may be for another
1220 * swap device which has been swapoff. And in do_swap_page(), after
1221 * the page is read from the swap device, the PTE is verified not
1222 * changed with the page table locked to check whether the swap device
1223 * has been swapoff or swapoff+swapon.
1225 struct swap_info_struct
*get_swap_device(swp_entry_t entry
)
1227 struct swap_info_struct
*si
;
1228 unsigned long offset
;
1232 si
= swp_swap_info(entry
);
1237 if (!(si
->flags
& SWP_VALID
))
1239 offset
= swp_offset(entry
);
1240 if (offset
>= si
->max
)
1245 pr_err("%s: %s%08lx\n", __func__
, Bad_file
, entry
.val
);
1253 static unsigned char __swap_entry_free(struct swap_info_struct
*p
,
1254 swp_entry_t entry
, unsigned char usage
)
1256 struct swap_cluster_info
*ci
;
1257 unsigned long offset
= swp_offset(entry
);
1259 ci
= lock_cluster_or_swap_info(p
, offset
);
1260 usage
= __swap_entry_free_locked(p
, offset
, usage
);
1261 unlock_cluster_or_swap_info(p
, ci
);
1263 free_swap_slot(entry
);
1268 static void swap_entry_free(struct swap_info_struct
*p
, swp_entry_t entry
)
1270 struct swap_cluster_info
*ci
;
1271 unsigned long offset
= swp_offset(entry
);
1272 unsigned char count
;
1274 ci
= lock_cluster(p
, offset
);
1275 count
= p
->swap_map
[offset
];
1276 VM_BUG_ON(count
!= SWAP_HAS_CACHE
);
1277 p
->swap_map
[offset
] = 0;
1278 dec_cluster_info_page(p
, p
->cluster_info
, offset
);
1281 mem_cgroup_uncharge_swap(entry
, 1);
1282 swap_range_free(p
, offset
, 1);
1286 * Caller has made sure that the swap device corresponding to entry
1287 * is still around or has not been recycled.
1289 void swap_free(swp_entry_t entry
)
1291 struct swap_info_struct
*p
;
1293 p
= _swap_info_get(entry
);
1295 __swap_entry_free(p
, entry
, 1);
1299 * Called after dropping swapcache to decrease refcnt to swap entries.
1301 void put_swap_page(struct page
*page
, swp_entry_t entry
)
1303 unsigned long offset
= swp_offset(entry
);
1304 unsigned long idx
= offset
/ SWAPFILE_CLUSTER
;
1305 struct swap_cluster_info
*ci
;
1306 struct swap_info_struct
*si
;
1308 unsigned int i
, free_entries
= 0;
1310 int size
= swap_entry_size(hpage_nr_pages(page
));
1312 si
= _swap_info_get(entry
);
1316 ci
= lock_cluster_or_swap_info(si
, offset
);
1317 if (size
== SWAPFILE_CLUSTER
) {
1318 VM_BUG_ON(!cluster_is_huge(ci
));
1319 map
= si
->swap_map
+ offset
;
1320 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++) {
1322 VM_BUG_ON(!(val
& SWAP_HAS_CACHE
));
1323 if (val
== SWAP_HAS_CACHE
)
1326 cluster_clear_huge(ci
);
1327 if (free_entries
== SWAPFILE_CLUSTER
) {
1328 unlock_cluster_or_swap_info(si
, ci
);
1329 spin_lock(&si
->lock
);
1330 mem_cgroup_uncharge_swap(entry
, SWAPFILE_CLUSTER
);
1331 swap_free_cluster(si
, idx
);
1332 spin_unlock(&si
->lock
);
1336 for (i
= 0; i
< size
; i
++, entry
.val
++) {
1337 if (!__swap_entry_free_locked(si
, offset
+ i
, SWAP_HAS_CACHE
)) {
1338 unlock_cluster_or_swap_info(si
, ci
);
1339 free_swap_slot(entry
);
1342 lock_cluster_or_swap_info(si
, offset
);
1345 unlock_cluster_or_swap_info(si
, ci
);
1348 #ifdef CONFIG_THP_SWAP
1349 int split_swap_cluster(swp_entry_t entry
)
1351 struct swap_info_struct
*si
;
1352 struct swap_cluster_info
*ci
;
1353 unsigned long offset
= swp_offset(entry
);
1355 si
= _swap_info_get(entry
);
1358 ci
= lock_cluster(si
, offset
);
1359 cluster_clear_huge(ci
);
1365 static int swp_entry_cmp(const void *ent1
, const void *ent2
)
1367 const swp_entry_t
*e1
= ent1
, *e2
= ent2
;
1369 return (int)swp_type(*e1
) - (int)swp_type(*e2
);
1372 void swapcache_free_entries(swp_entry_t
*entries
, int n
)
1374 struct swap_info_struct
*p
, *prev
;
1384 * Sort swap entries by swap device, so each lock is only taken once.
1385 * nr_swapfiles isn't absolutely correct, but the overhead of sort() is
1386 * so low that it isn't necessary to optimize further.
1388 if (nr_swapfiles
> 1)
1389 sort(entries
, n
, sizeof(entries
[0]), swp_entry_cmp
, NULL
);
1390 for (i
= 0; i
< n
; ++i
) {
1391 p
= swap_info_get_cont(entries
[i
], prev
);
1393 swap_entry_free(p
, entries
[i
]);
1397 spin_unlock(&p
->lock
);
1401 * How many references to page are currently swapped out?
1402 * This does not give an exact answer when swap count is continued,
1403 * but does include the high COUNT_CONTINUED flag to allow for that.
1405 int page_swapcount(struct page
*page
)
1408 struct swap_info_struct
*p
;
1409 struct swap_cluster_info
*ci
;
1411 unsigned long offset
;
1413 entry
.val
= page_private(page
);
1414 p
= _swap_info_get(entry
);
1416 offset
= swp_offset(entry
);
1417 ci
= lock_cluster_or_swap_info(p
, offset
);
1418 count
= swap_count(p
->swap_map
[offset
]);
1419 unlock_cluster_or_swap_info(p
, ci
);
1424 int __swap_count(swp_entry_t entry
)
1426 struct swap_info_struct
*si
;
1427 pgoff_t offset
= swp_offset(entry
);
1430 si
= get_swap_device(entry
);
1432 count
= swap_count(si
->swap_map
[offset
]);
1433 put_swap_device(si
);
1438 static int swap_swapcount(struct swap_info_struct
*si
, swp_entry_t entry
)
1441 pgoff_t offset
= swp_offset(entry
);
1442 struct swap_cluster_info
*ci
;
1444 ci
= lock_cluster_or_swap_info(si
, offset
);
1445 count
= swap_count(si
->swap_map
[offset
]);
1446 unlock_cluster_or_swap_info(si
, ci
);
1451 * How many references to @entry are currently swapped out?
1452 * This does not give an exact answer when swap count is continued,
1453 * but does include the high COUNT_CONTINUED flag to allow for that.
1455 int __swp_swapcount(swp_entry_t entry
)
1458 struct swap_info_struct
*si
;
1460 si
= get_swap_device(entry
);
1462 count
= swap_swapcount(si
, entry
);
1463 put_swap_device(si
);
1469 * How many references to @entry are currently swapped out?
1470 * This considers COUNT_CONTINUED so it returns exact answer.
1472 int swp_swapcount(swp_entry_t entry
)
1474 int count
, tmp_count
, n
;
1475 struct swap_info_struct
*p
;
1476 struct swap_cluster_info
*ci
;
1481 p
= _swap_info_get(entry
);
1485 offset
= swp_offset(entry
);
1487 ci
= lock_cluster_or_swap_info(p
, offset
);
1489 count
= swap_count(p
->swap_map
[offset
]);
1490 if (!(count
& COUNT_CONTINUED
))
1493 count
&= ~COUNT_CONTINUED
;
1494 n
= SWAP_MAP_MAX
+ 1;
1496 page
= vmalloc_to_page(p
->swap_map
+ offset
);
1497 offset
&= ~PAGE_MASK
;
1498 VM_BUG_ON(page_private(page
) != SWP_CONTINUED
);
1501 page
= list_next_entry(page
, lru
);
1502 map
= kmap_atomic(page
);
1503 tmp_count
= map
[offset
];
1506 count
+= (tmp_count
& ~COUNT_CONTINUED
) * n
;
1507 n
*= (SWAP_CONT_MAX
+ 1);
1508 } while (tmp_count
& COUNT_CONTINUED
);
1510 unlock_cluster_or_swap_info(p
, ci
);
1514 static bool swap_page_trans_huge_swapped(struct swap_info_struct
*si
,
1517 struct swap_cluster_info
*ci
;
1518 unsigned char *map
= si
->swap_map
;
1519 unsigned long roffset
= swp_offset(entry
);
1520 unsigned long offset
= round_down(roffset
, SWAPFILE_CLUSTER
);
1524 ci
= lock_cluster_or_swap_info(si
, offset
);
1525 if (!ci
|| !cluster_is_huge(ci
)) {
1526 if (swap_count(map
[roffset
]))
1530 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++) {
1531 if (swap_count(map
[offset
+ i
])) {
1537 unlock_cluster_or_swap_info(si
, ci
);
1541 static bool page_swapped(struct page
*page
)
1544 struct swap_info_struct
*si
;
1546 if (!IS_ENABLED(CONFIG_THP_SWAP
) || likely(!PageTransCompound(page
)))
1547 return page_swapcount(page
) != 0;
1549 page
= compound_head(page
);
1550 entry
.val
= page_private(page
);
1551 si
= _swap_info_get(entry
);
1553 return swap_page_trans_huge_swapped(si
, entry
);
1557 static int page_trans_huge_map_swapcount(struct page
*page
, int *total_mapcount
,
1558 int *total_swapcount
)
1560 int i
, map_swapcount
, _total_mapcount
, _total_swapcount
;
1561 unsigned long offset
= 0;
1562 struct swap_info_struct
*si
;
1563 struct swap_cluster_info
*ci
= NULL
;
1564 unsigned char *map
= NULL
;
1565 int mapcount
, swapcount
= 0;
1567 /* hugetlbfs shouldn't call it */
1568 VM_BUG_ON_PAGE(PageHuge(page
), page
);
1570 if (!IS_ENABLED(CONFIG_THP_SWAP
) || likely(!PageTransCompound(page
))) {
1571 mapcount
= page_trans_huge_mapcount(page
, total_mapcount
);
1572 if (PageSwapCache(page
))
1573 swapcount
= page_swapcount(page
);
1574 if (total_swapcount
)
1575 *total_swapcount
= swapcount
;
1576 return mapcount
+ swapcount
;
1579 page
= compound_head(page
);
1581 _total_mapcount
= _total_swapcount
= map_swapcount
= 0;
1582 if (PageSwapCache(page
)) {
1585 entry
.val
= page_private(page
);
1586 si
= _swap_info_get(entry
);
1589 offset
= swp_offset(entry
);
1593 ci
= lock_cluster(si
, offset
);
1594 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1595 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
1596 _total_mapcount
+= mapcount
;
1598 swapcount
= swap_count(map
[offset
+ i
]);
1599 _total_swapcount
+= swapcount
;
1601 map_swapcount
= max(map_swapcount
, mapcount
+ swapcount
);
1604 if (PageDoubleMap(page
)) {
1606 _total_mapcount
-= HPAGE_PMD_NR
;
1608 mapcount
= compound_mapcount(page
);
1609 map_swapcount
+= mapcount
;
1610 _total_mapcount
+= mapcount
;
1612 *total_mapcount
= _total_mapcount
;
1613 if (total_swapcount
)
1614 *total_swapcount
= _total_swapcount
;
1616 return map_swapcount
;
1620 * We can write to an anon page without COW if there are no other references
1621 * to it. And as a side-effect, free up its swap: because the old content
1622 * on disk will never be read, and seeking back there to write new content
1623 * later would only waste time away from clustering.
1625 * NOTE: total_map_swapcount should not be relied upon by the caller if
1626 * reuse_swap_page() returns false, but it may be always overwritten
1627 * (see the other implementation for CONFIG_SWAP=n).
1629 bool reuse_swap_page(struct page
*page
, int *total_map_swapcount
)
1631 int count
, total_mapcount
, total_swapcount
;
1633 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1634 if (unlikely(PageKsm(page
)))
1636 count
= page_trans_huge_map_swapcount(page
, &total_mapcount
,
1638 if (total_map_swapcount
)
1639 *total_map_swapcount
= total_mapcount
+ total_swapcount
;
1640 if (count
== 1 && PageSwapCache(page
) &&
1641 (likely(!PageTransCompound(page
)) ||
1642 /* The remaining swap count will be freed soon */
1643 total_swapcount
== page_swapcount(page
))) {
1644 if (!PageWriteback(page
)) {
1645 page
= compound_head(page
);
1646 delete_from_swap_cache(page
);
1650 struct swap_info_struct
*p
;
1652 entry
.val
= page_private(page
);
1653 p
= swap_info_get(entry
);
1654 if (p
->flags
& SWP_STABLE_WRITES
) {
1655 spin_unlock(&p
->lock
);
1658 spin_unlock(&p
->lock
);
1666 * If swap is getting full, or if there are no more mappings of this page,
1667 * then try_to_free_swap is called to free its swap space.
1669 int try_to_free_swap(struct page
*page
)
1671 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1673 if (!PageSwapCache(page
))
1675 if (PageWriteback(page
))
1677 if (page_swapped(page
))
1681 * Once hibernation has begun to create its image of memory,
1682 * there's a danger that one of the calls to try_to_free_swap()
1683 * - most probably a call from __try_to_reclaim_swap() while
1684 * hibernation is allocating its own swap pages for the image,
1685 * but conceivably even a call from memory reclaim - will free
1686 * the swap from a page which has already been recorded in the
1687 * image as a clean swapcache page, and then reuse its swap for
1688 * another page of the image. On waking from hibernation, the
1689 * original page might be freed under memory pressure, then
1690 * later read back in from swap, now with the wrong data.
1692 * Hibernation suspends storage while it is writing the image
1693 * to disk so check that here.
1695 if (pm_suspended_storage())
1698 page
= compound_head(page
);
1699 delete_from_swap_cache(page
);
1705 * Free the swap entry like above, but also try to
1706 * free the page cache entry if it is the last user.
1708 int free_swap_and_cache(swp_entry_t entry
)
1710 struct swap_info_struct
*p
;
1711 unsigned char count
;
1713 if (non_swap_entry(entry
))
1716 p
= _swap_info_get(entry
);
1718 count
= __swap_entry_free(p
, entry
, 1);
1719 if (count
== SWAP_HAS_CACHE
&&
1720 !swap_page_trans_huge_swapped(p
, entry
))
1721 __try_to_reclaim_swap(p
, swp_offset(entry
),
1722 TTRS_UNMAPPED
| TTRS_FULL
);
1727 #ifdef CONFIG_HIBERNATION
1729 * Find the swap type that corresponds to given device (if any).
1731 * @offset - number of the PAGE_SIZE-sized block of the device, starting
1732 * from 0, in which the swap header is expected to be located.
1734 * This is needed for the suspend to disk (aka swsusp).
1736 int swap_type_of(dev_t device
, sector_t offset
, struct block_device
**bdev_p
)
1738 struct block_device
*bdev
= NULL
;
1742 bdev
= bdget(device
);
1744 spin_lock(&swap_lock
);
1745 for (type
= 0; type
< nr_swapfiles
; type
++) {
1746 struct swap_info_struct
*sis
= swap_info
[type
];
1748 if (!(sis
->flags
& SWP_WRITEOK
))
1753 *bdev_p
= bdgrab(sis
->bdev
);
1755 spin_unlock(&swap_lock
);
1758 if (bdev
== sis
->bdev
) {
1759 struct swap_extent
*se
= first_se(sis
);
1761 if (se
->start_block
== offset
) {
1763 *bdev_p
= bdgrab(sis
->bdev
);
1765 spin_unlock(&swap_lock
);
1771 spin_unlock(&swap_lock
);
1779 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
1780 * corresponding to given index in swap_info (swap type).
1782 sector_t
swapdev_block(int type
, pgoff_t offset
)
1784 struct block_device
*bdev
;
1785 struct swap_info_struct
*si
= swap_type_to_swap_info(type
);
1787 if (!si
|| !(si
->flags
& SWP_WRITEOK
))
1789 return map_swap_entry(swp_entry(type
, offset
), &bdev
);
1793 * Return either the total number of swap pages of given type, or the number
1794 * of free pages of that type (depending on @free)
1796 * This is needed for software suspend
1798 unsigned int count_swap_pages(int type
, int free
)
1802 spin_lock(&swap_lock
);
1803 if ((unsigned int)type
< nr_swapfiles
) {
1804 struct swap_info_struct
*sis
= swap_info
[type
];
1806 spin_lock(&sis
->lock
);
1807 if (sis
->flags
& SWP_WRITEOK
) {
1810 n
-= sis
->inuse_pages
;
1812 spin_unlock(&sis
->lock
);
1814 spin_unlock(&swap_lock
);
1817 #endif /* CONFIG_HIBERNATION */
1819 static inline int pte_same_as_swp(pte_t pte
, pte_t swp_pte
)
1821 return pte_same(pte_swp_clear_soft_dirty(pte
), swp_pte
);
1825 * No need to decide whether this PTE shares the swap entry with others,
1826 * just let do_wp_page work it out if a write is requested later - to
1827 * force COW, vm_page_prot omits write permission from any private vma.
1829 static int unuse_pte(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1830 unsigned long addr
, swp_entry_t entry
, struct page
*page
)
1832 struct page
*swapcache
;
1833 struct mem_cgroup
*memcg
;
1839 page
= ksm_might_need_to_copy(page
, vma
, addr
);
1840 if (unlikely(!page
))
1843 if (mem_cgroup_try_charge(page
, vma
->vm_mm
, GFP_KERNEL
,
1849 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
1850 if (unlikely(!pte_same_as_swp(*pte
, swp_entry_to_pte(entry
)))) {
1851 mem_cgroup_cancel_charge(page
, memcg
, false);
1856 dec_mm_counter(vma
->vm_mm
, MM_SWAPENTS
);
1857 inc_mm_counter(vma
->vm_mm
, MM_ANONPAGES
);
1859 set_pte_at(vma
->vm_mm
, addr
, pte
,
1860 pte_mkold(mk_pte(page
, vma
->vm_page_prot
)));
1861 if (page
== swapcache
) {
1862 page_add_anon_rmap(page
, vma
, addr
, false);
1863 mem_cgroup_commit_charge(page
, memcg
, true, false);
1864 } else { /* ksm created a completely new copy */
1865 page_add_new_anon_rmap(page
, vma
, addr
, false);
1866 mem_cgroup_commit_charge(page
, memcg
, false, false);
1867 lru_cache_add_active_or_unevictable(page
, vma
);
1871 * Move the page to the active list so it is not
1872 * immediately swapped out again after swapon.
1874 activate_page(page
);
1876 pte_unmap_unlock(pte
, ptl
);
1878 if (page
!= swapcache
) {
1885 static int unuse_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1886 unsigned long addr
, unsigned long end
,
1887 unsigned int type
, bool frontswap
,
1888 unsigned long *fs_pages_to_unuse
)
1893 struct swap_info_struct
*si
;
1894 unsigned long offset
;
1896 volatile unsigned char *swap_map
;
1898 si
= swap_info
[type
];
1899 pte
= pte_offset_map(pmd
, addr
);
1901 struct vm_fault vmf
;
1903 if (!is_swap_pte(*pte
))
1906 entry
= pte_to_swp_entry(*pte
);
1907 if (swp_type(entry
) != type
)
1910 offset
= swp_offset(entry
);
1911 if (frontswap
&& !frontswap_test(si
, offset
))
1915 swap_map
= &si
->swap_map
[offset
];
1916 page
= lookup_swap_cache(entry
, vma
, addr
);
1921 page
= swapin_readahead(entry
, GFP_HIGHUSER_MOVABLE
,
1925 if (*swap_map
== 0 || *swap_map
== SWAP_MAP_BAD
)
1931 wait_on_page_writeback(page
);
1932 ret
= unuse_pte(vma
, pmd
, addr
, entry
, page
);
1939 try_to_free_swap(page
);
1943 if (*fs_pages_to_unuse
&& !--(*fs_pages_to_unuse
)) {
1944 ret
= FRONTSWAP_PAGES_UNUSED
;
1948 pte
= pte_offset_map(pmd
, addr
);
1949 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1957 static inline int unuse_pmd_range(struct vm_area_struct
*vma
, pud_t
*pud
,
1958 unsigned long addr
, unsigned long end
,
1959 unsigned int type
, bool frontswap
,
1960 unsigned long *fs_pages_to_unuse
)
1966 pmd
= pmd_offset(pud
, addr
);
1969 next
= pmd_addr_end(addr
, end
);
1970 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
1972 ret
= unuse_pte_range(vma
, pmd
, addr
, next
, type
,
1973 frontswap
, fs_pages_to_unuse
);
1976 } while (pmd
++, addr
= next
, addr
!= end
);
1980 static inline int unuse_pud_range(struct vm_area_struct
*vma
, p4d_t
*p4d
,
1981 unsigned long addr
, unsigned long end
,
1982 unsigned int type
, bool frontswap
,
1983 unsigned long *fs_pages_to_unuse
)
1989 pud
= pud_offset(p4d
, addr
);
1991 next
= pud_addr_end(addr
, end
);
1992 if (pud_none_or_clear_bad(pud
))
1994 ret
= unuse_pmd_range(vma
, pud
, addr
, next
, type
,
1995 frontswap
, fs_pages_to_unuse
);
1998 } while (pud
++, addr
= next
, addr
!= end
);
2002 static inline int unuse_p4d_range(struct vm_area_struct
*vma
, pgd_t
*pgd
,
2003 unsigned long addr
, unsigned long end
,
2004 unsigned int type
, bool frontswap
,
2005 unsigned long *fs_pages_to_unuse
)
2011 p4d
= p4d_offset(pgd
, addr
);
2013 next
= p4d_addr_end(addr
, end
);
2014 if (p4d_none_or_clear_bad(p4d
))
2016 ret
= unuse_pud_range(vma
, p4d
, addr
, next
, type
,
2017 frontswap
, fs_pages_to_unuse
);
2020 } while (p4d
++, addr
= next
, addr
!= end
);
2024 static int unuse_vma(struct vm_area_struct
*vma
, unsigned int type
,
2025 bool frontswap
, unsigned long *fs_pages_to_unuse
)
2028 unsigned long addr
, end
, next
;
2031 addr
= vma
->vm_start
;
2034 pgd
= pgd_offset(vma
->vm_mm
, addr
);
2036 next
= pgd_addr_end(addr
, end
);
2037 if (pgd_none_or_clear_bad(pgd
))
2039 ret
= unuse_p4d_range(vma
, pgd
, addr
, next
, type
,
2040 frontswap
, fs_pages_to_unuse
);
2043 } while (pgd
++, addr
= next
, addr
!= end
);
2047 static int unuse_mm(struct mm_struct
*mm
, unsigned int type
,
2048 bool frontswap
, unsigned long *fs_pages_to_unuse
)
2050 struct vm_area_struct
*vma
;
2053 down_read(&mm
->mmap_sem
);
2054 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2055 if (vma
->anon_vma
) {
2056 ret
= unuse_vma(vma
, type
, frontswap
,
2063 up_read(&mm
->mmap_sem
);
2068 * Scan swap_map (or frontswap_map if frontswap parameter is true)
2069 * from current position to next entry still in use. Return 0
2070 * if there are no inuse entries after prev till end of the map.
2072 static unsigned int find_next_to_unuse(struct swap_info_struct
*si
,
2073 unsigned int prev
, bool frontswap
)
2076 unsigned char count
;
2079 * No need for swap_lock here: we're just looking
2080 * for whether an entry is in use, not modifying it; false
2081 * hits are okay, and sys_swapoff() has already prevented new
2082 * allocations from this area (while holding swap_lock).
2084 for (i
= prev
+ 1; i
< si
->max
; i
++) {
2085 count
= READ_ONCE(si
->swap_map
[i
]);
2086 if (count
&& swap_count(count
) != SWAP_MAP_BAD
)
2087 if (!frontswap
|| frontswap_test(si
, i
))
2089 if ((i
% LATENCY_LIMIT
) == 0)
2100 * If the boolean frontswap is true, only unuse pages_to_unuse pages;
2101 * pages_to_unuse==0 means all pages; ignored if frontswap is false
2103 int try_to_unuse(unsigned int type
, bool frontswap
,
2104 unsigned long pages_to_unuse
)
2106 struct mm_struct
*prev_mm
;
2107 struct mm_struct
*mm
;
2108 struct list_head
*p
;
2110 struct swap_info_struct
*si
= swap_info
[type
];
2115 if (!READ_ONCE(si
->inuse_pages
))
2122 retval
= shmem_unuse(type
, frontswap
, &pages_to_unuse
);
2129 spin_lock(&mmlist_lock
);
2130 p
= &init_mm
.mmlist
;
2131 while (READ_ONCE(si
->inuse_pages
) &&
2132 !signal_pending(current
) &&
2133 (p
= p
->next
) != &init_mm
.mmlist
) {
2135 mm
= list_entry(p
, struct mm_struct
, mmlist
);
2136 if (!mmget_not_zero(mm
))
2138 spin_unlock(&mmlist_lock
);
2141 retval
= unuse_mm(mm
, type
, frontswap
, &pages_to_unuse
);
2149 * Make sure that we aren't completely killing
2150 * interactive performance.
2153 spin_lock(&mmlist_lock
);
2155 spin_unlock(&mmlist_lock
);
2160 while (READ_ONCE(si
->inuse_pages
) &&
2161 !signal_pending(current
) &&
2162 (i
= find_next_to_unuse(si
, i
, frontswap
)) != 0) {
2164 entry
= swp_entry(type
, i
);
2165 page
= find_get_page(swap_address_space(entry
), i
);
2170 * It is conceivable that a racing task removed this page from
2171 * swap cache just before we acquired the page lock. The page
2172 * might even be back in swap cache on another swap area. But
2173 * that is okay, try_to_free_swap() only removes stale pages.
2176 wait_on_page_writeback(page
);
2177 try_to_free_swap(page
);
2182 * For frontswap, we just need to unuse pages_to_unuse, if
2183 * it was specified. Need not check frontswap again here as
2184 * we already zeroed out pages_to_unuse if not frontswap.
2186 if (pages_to_unuse
&& --pages_to_unuse
== 0)
2191 * Lets check again to see if there are still swap entries in the map.
2192 * If yes, we would need to do retry the unuse logic again.
2193 * Under global memory pressure, swap entries can be reinserted back
2194 * into process space after the mmlist loop above passes over them.
2196 * Limit the number of retries? No: when mmget_not_zero() above fails,
2197 * that mm is likely to be freeing swap from exit_mmap(), which proceeds
2198 * at its own independent pace; and even shmem_writepage() could have
2199 * been preempted after get_swap_page(), temporarily hiding that swap.
2200 * It's easy and robust (though cpu-intensive) just to keep retrying.
2202 if (READ_ONCE(si
->inuse_pages
)) {
2203 if (!signal_pending(current
))
2208 return (retval
== FRONTSWAP_PAGES_UNUSED
) ? 0 : retval
;
2212 * After a successful try_to_unuse, if no swap is now in use, we know
2213 * we can empty the mmlist. swap_lock must be held on entry and exit.
2214 * Note that mmlist_lock nests inside swap_lock, and an mm must be
2215 * added to the mmlist just after page_duplicate - before would be racy.
2217 static void drain_mmlist(void)
2219 struct list_head
*p
, *next
;
2222 for (type
= 0; type
< nr_swapfiles
; type
++)
2223 if (swap_info
[type
]->inuse_pages
)
2225 spin_lock(&mmlist_lock
);
2226 list_for_each_safe(p
, next
, &init_mm
.mmlist
)
2228 spin_unlock(&mmlist_lock
);
2232 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
2233 * corresponds to page offset for the specified swap entry.
2234 * Note that the type of this function is sector_t, but it returns page offset
2235 * into the bdev, not sector offset.
2237 static sector_t
map_swap_entry(swp_entry_t entry
, struct block_device
**bdev
)
2239 struct swap_info_struct
*sis
;
2240 struct swap_extent
*se
;
2243 sis
= swp_swap_info(entry
);
2246 offset
= swp_offset(entry
);
2247 se
= offset_to_swap_extent(sis
, offset
);
2248 return se
->start_block
+ (offset
- se
->start_page
);
2252 * Returns the page offset into bdev for the specified page's swap entry.
2254 sector_t
map_swap_page(struct page
*page
, struct block_device
**bdev
)
2257 entry
.val
= page_private(page
);
2258 return map_swap_entry(entry
, bdev
);
2262 * Free all of a swapdev's extent information
2264 static void destroy_swap_extents(struct swap_info_struct
*sis
)
2266 while (!RB_EMPTY_ROOT(&sis
->swap_extent_root
)) {
2267 struct rb_node
*rb
= sis
->swap_extent_root
.rb_node
;
2268 struct swap_extent
*se
= rb_entry(rb
, struct swap_extent
, rb_node
);
2270 rb_erase(rb
, &sis
->swap_extent_root
);
2274 if (sis
->flags
& SWP_ACTIVATED
) {
2275 struct file
*swap_file
= sis
->swap_file
;
2276 struct address_space
*mapping
= swap_file
->f_mapping
;
2278 sis
->flags
&= ~SWP_ACTIVATED
;
2279 if (mapping
->a_ops
->swap_deactivate
)
2280 mapping
->a_ops
->swap_deactivate(swap_file
);
2285 * Add a block range (and the corresponding page range) into this swapdev's
2288 * This function rather assumes that it is called in ascending page order.
2291 add_swap_extent(struct swap_info_struct
*sis
, unsigned long start_page
,
2292 unsigned long nr_pages
, sector_t start_block
)
2294 struct rb_node
**link
= &sis
->swap_extent_root
.rb_node
, *parent
= NULL
;
2295 struct swap_extent
*se
;
2296 struct swap_extent
*new_se
;
2299 * place the new node at the right most since the
2300 * function is called in ascending page order.
2304 link
= &parent
->rb_right
;
2308 se
= rb_entry(parent
, struct swap_extent
, rb_node
);
2309 BUG_ON(se
->start_page
+ se
->nr_pages
!= start_page
);
2310 if (se
->start_block
+ se
->nr_pages
== start_block
) {
2312 se
->nr_pages
+= nr_pages
;
2317 /* No merge, insert a new extent. */
2318 new_se
= kmalloc(sizeof(*se
), GFP_KERNEL
);
2321 new_se
->start_page
= start_page
;
2322 new_se
->nr_pages
= nr_pages
;
2323 new_se
->start_block
= start_block
;
2325 rb_link_node(&new_se
->rb_node
, parent
, link
);
2326 rb_insert_color(&new_se
->rb_node
, &sis
->swap_extent_root
);
2329 EXPORT_SYMBOL_GPL(add_swap_extent
);
2332 * A `swap extent' is a simple thing which maps a contiguous range of pages
2333 * onto a contiguous range of disk blocks. An ordered list of swap extents
2334 * is built at swapon time and is then used at swap_writepage/swap_readpage
2335 * time for locating where on disk a page belongs.
2337 * If the swapfile is an S_ISBLK block device, a single extent is installed.
2338 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
2339 * swap files identically.
2341 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
2342 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
2343 * swapfiles are handled *identically* after swapon time.
2345 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
2346 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
2347 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
2348 * requirements, they are simply tossed out - we will never use those blocks
2351 * For all swap devices we set S_SWAPFILE across the life of the swapon. This
2352 * prevents users from writing to the swap device, which will corrupt memory.
2354 * The amount of disk space which a single swap extent represents varies.
2355 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
2356 * extents in the list. To avoid much list walking, we cache the previous
2357 * search location in `curr_swap_extent', and start new searches from there.
2358 * This is extremely effective. The average number of iterations in
2359 * map_swap_page() has been measured at about 0.3 per page. - akpm.
2361 static int setup_swap_extents(struct swap_info_struct
*sis
, sector_t
*span
)
2363 struct file
*swap_file
= sis
->swap_file
;
2364 struct address_space
*mapping
= swap_file
->f_mapping
;
2365 struct inode
*inode
= mapping
->host
;
2368 if (S_ISBLK(inode
->i_mode
)) {
2369 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
2374 if (mapping
->a_ops
->swap_activate
) {
2375 ret
= mapping
->a_ops
->swap_activate(sis
, swap_file
, span
);
2377 sis
->flags
|= SWP_ACTIVATED
;
2379 sis
->flags
|= SWP_FS
;
2380 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
2386 return generic_swapfile_activate(sis
, swap_file
, span
);
2389 static int swap_node(struct swap_info_struct
*p
)
2391 struct block_device
*bdev
;
2396 bdev
= p
->swap_file
->f_inode
->i_sb
->s_bdev
;
2398 return bdev
? bdev
->bd_disk
->node_id
: NUMA_NO_NODE
;
2401 static void setup_swap_info(struct swap_info_struct
*p
, int prio
,
2402 unsigned char *swap_map
,
2403 struct swap_cluster_info
*cluster_info
)
2410 p
->prio
= --least_priority
;
2412 * the plist prio is negated because plist ordering is
2413 * low-to-high, while swap ordering is high-to-low
2415 p
->list
.prio
= -p
->prio
;
2418 p
->avail_lists
[i
].prio
= -p
->prio
;
2420 if (swap_node(p
) == i
)
2421 p
->avail_lists
[i
].prio
= 1;
2423 p
->avail_lists
[i
].prio
= -p
->prio
;
2426 p
->swap_map
= swap_map
;
2427 p
->cluster_info
= cluster_info
;
2430 static void _enable_swap_info(struct swap_info_struct
*p
)
2432 p
->flags
|= SWP_WRITEOK
| SWP_VALID
;
2433 atomic_long_add(p
->pages
, &nr_swap_pages
);
2434 total_swap_pages
+= p
->pages
;
2436 assert_spin_locked(&swap_lock
);
2438 * both lists are plists, and thus priority ordered.
2439 * swap_active_head needs to be priority ordered for swapoff(),
2440 * which on removal of any swap_info_struct with an auto-assigned
2441 * (i.e. negative) priority increments the auto-assigned priority
2442 * of any lower-priority swap_info_structs.
2443 * swap_avail_head needs to be priority ordered for get_swap_page(),
2444 * which allocates swap pages from the highest available priority
2447 plist_add(&p
->list
, &swap_active_head
);
2448 add_to_avail_list(p
);
2451 static void enable_swap_info(struct swap_info_struct
*p
, int prio
,
2452 unsigned char *swap_map
,
2453 struct swap_cluster_info
*cluster_info
,
2454 unsigned long *frontswap_map
)
2456 frontswap_init(p
->type
, frontswap_map
);
2457 spin_lock(&swap_lock
);
2458 spin_lock(&p
->lock
);
2459 setup_swap_info(p
, prio
, swap_map
, cluster_info
);
2460 spin_unlock(&p
->lock
);
2461 spin_unlock(&swap_lock
);
2463 * Guarantee swap_map, cluster_info, etc. fields are valid
2464 * between get/put_swap_device() if SWP_VALID bit is set
2467 spin_lock(&swap_lock
);
2468 spin_lock(&p
->lock
);
2469 _enable_swap_info(p
);
2470 spin_unlock(&p
->lock
);
2471 spin_unlock(&swap_lock
);
2474 static void reinsert_swap_info(struct swap_info_struct
*p
)
2476 spin_lock(&swap_lock
);
2477 spin_lock(&p
->lock
);
2478 setup_swap_info(p
, p
->prio
, p
->swap_map
, p
->cluster_info
);
2479 _enable_swap_info(p
);
2480 spin_unlock(&p
->lock
);
2481 spin_unlock(&swap_lock
);
2484 bool has_usable_swap(void)
2488 spin_lock(&swap_lock
);
2489 if (plist_head_empty(&swap_active_head
))
2491 spin_unlock(&swap_lock
);
2495 SYSCALL_DEFINE1(swapoff
, const char __user
*, specialfile
)
2497 struct swap_info_struct
*p
= NULL
;
2498 unsigned char *swap_map
;
2499 struct swap_cluster_info
*cluster_info
;
2500 unsigned long *frontswap_map
;
2501 struct file
*swap_file
, *victim
;
2502 struct address_space
*mapping
;
2503 struct inode
*inode
;
2504 struct filename
*pathname
;
2506 unsigned int old_block_size
;
2508 if (!capable(CAP_SYS_ADMIN
))
2511 BUG_ON(!current
->mm
);
2513 pathname
= getname(specialfile
);
2514 if (IS_ERR(pathname
))
2515 return PTR_ERR(pathname
);
2517 victim
= file_open_name(pathname
, O_RDWR
|O_LARGEFILE
, 0);
2518 err
= PTR_ERR(victim
);
2522 mapping
= victim
->f_mapping
;
2523 spin_lock(&swap_lock
);
2524 plist_for_each_entry(p
, &swap_active_head
, list
) {
2525 if (p
->flags
& SWP_WRITEOK
) {
2526 if (p
->swap_file
->f_mapping
== mapping
) {
2534 spin_unlock(&swap_lock
);
2537 if (!security_vm_enough_memory_mm(current
->mm
, p
->pages
))
2538 vm_unacct_memory(p
->pages
);
2541 spin_unlock(&swap_lock
);
2544 del_from_avail_list(p
);
2545 spin_lock(&p
->lock
);
2547 struct swap_info_struct
*si
= p
;
2550 plist_for_each_entry_continue(si
, &swap_active_head
, list
) {
2553 for_each_node(nid
) {
2554 if (si
->avail_lists
[nid
].prio
!= 1)
2555 si
->avail_lists
[nid
].prio
--;
2560 plist_del(&p
->list
, &swap_active_head
);
2561 atomic_long_sub(p
->pages
, &nr_swap_pages
);
2562 total_swap_pages
-= p
->pages
;
2563 p
->flags
&= ~SWP_WRITEOK
;
2564 spin_unlock(&p
->lock
);
2565 spin_unlock(&swap_lock
);
2567 disable_swap_slots_cache_lock();
2569 set_current_oom_origin();
2570 err
= try_to_unuse(p
->type
, false, 0); /* force unuse all pages */
2571 clear_current_oom_origin();
2574 /* re-insert swap space back into swap_list */
2575 reinsert_swap_info(p
);
2576 reenable_swap_slots_cache_unlock();
2580 reenable_swap_slots_cache_unlock();
2582 spin_lock(&swap_lock
);
2583 spin_lock(&p
->lock
);
2584 p
->flags
&= ~SWP_VALID
; /* mark swap device as invalid */
2585 spin_unlock(&p
->lock
);
2586 spin_unlock(&swap_lock
);
2588 * wait for swap operations protected by get/put_swap_device()
2593 flush_work(&p
->discard_work
);
2595 destroy_swap_extents(p
);
2596 if (p
->flags
& SWP_CONTINUED
)
2597 free_swap_count_continuations(p
);
2599 if (!p
->bdev
|| !blk_queue_nonrot(bdev_get_queue(p
->bdev
)))
2600 atomic_dec(&nr_rotate_swap
);
2602 mutex_lock(&swapon_mutex
);
2603 spin_lock(&swap_lock
);
2604 spin_lock(&p
->lock
);
2607 /* wait for anyone still in scan_swap_map */
2608 p
->highest_bit
= 0; /* cuts scans short */
2609 while (p
->flags
>= SWP_SCANNING
) {
2610 spin_unlock(&p
->lock
);
2611 spin_unlock(&swap_lock
);
2612 schedule_timeout_uninterruptible(1);
2613 spin_lock(&swap_lock
);
2614 spin_lock(&p
->lock
);
2617 swap_file
= p
->swap_file
;
2618 old_block_size
= p
->old_block_size
;
2619 p
->swap_file
= NULL
;
2621 swap_map
= p
->swap_map
;
2623 cluster_info
= p
->cluster_info
;
2624 p
->cluster_info
= NULL
;
2625 frontswap_map
= frontswap_map_get(p
);
2626 spin_unlock(&p
->lock
);
2627 spin_unlock(&swap_lock
);
2628 frontswap_invalidate_area(p
->type
);
2629 frontswap_map_set(p
, NULL
);
2630 mutex_unlock(&swapon_mutex
);
2631 free_percpu(p
->percpu_cluster
);
2632 p
->percpu_cluster
= NULL
;
2634 kvfree(cluster_info
);
2635 kvfree(frontswap_map
);
2636 /* Destroy swap account information */
2637 swap_cgroup_swapoff(p
->type
);
2638 exit_swap_address_space(p
->type
);
2640 inode
= mapping
->host
;
2641 if (S_ISBLK(inode
->i_mode
)) {
2642 struct block_device
*bdev
= I_BDEV(inode
);
2644 set_blocksize(bdev
, old_block_size
);
2645 blkdev_put(bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
2649 inode
->i_flags
&= ~S_SWAPFILE
;
2650 inode_unlock(inode
);
2651 filp_close(swap_file
, NULL
);
2654 * Clear the SWP_USED flag after all resources are freed so that swapon
2655 * can reuse this swap_info in alloc_swap_info() safely. It is ok to
2656 * not hold p->lock after we cleared its SWP_WRITEOK.
2658 spin_lock(&swap_lock
);
2660 spin_unlock(&swap_lock
);
2663 atomic_inc(&proc_poll_event
);
2664 wake_up_interruptible(&proc_poll_wait
);
2667 filp_close(victim
, NULL
);
2673 #ifdef CONFIG_PROC_FS
2674 static __poll_t
swaps_poll(struct file
*file
, poll_table
*wait
)
2676 struct seq_file
*seq
= file
->private_data
;
2678 poll_wait(file
, &proc_poll_wait
, wait
);
2680 if (seq
->poll_event
!= atomic_read(&proc_poll_event
)) {
2681 seq
->poll_event
= atomic_read(&proc_poll_event
);
2682 return EPOLLIN
| EPOLLRDNORM
| EPOLLERR
| EPOLLPRI
;
2685 return EPOLLIN
| EPOLLRDNORM
;
2689 static void *swap_start(struct seq_file
*swap
, loff_t
*pos
)
2691 struct swap_info_struct
*si
;
2695 mutex_lock(&swapon_mutex
);
2698 return SEQ_START_TOKEN
;
2700 for (type
= 0; (si
= swap_type_to_swap_info(type
)); type
++) {
2701 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
2710 static void *swap_next(struct seq_file
*swap
, void *v
, loff_t
*pos
)
2712 struct swap_info_struct
*si
= v
;
2715 if (v
== SEQ_START_TOKEN
)
2718 type
= si
->type
+ 1;
2721 for (; (si
= swap_type_to_swap_info(type
)); type
++) {
2722 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
2730 static void swap_stop(struct seq_file
*swap
, void *v
)
2732 mutex_unlock(&swapon_mutex
);
2735 static int swap_show(struct seq_file
*swap
, void *v
)
2737 struct swap_info_struct
*si
= v
;
2741 if (si
== SEQ_START_TOKEN
) {
2742 seq_puts(swap
,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
2746 file
= si
->swap_file
;
2747 len
= seq_file_path(swap
, file
, " \t\n\\");
2748 seq_printf(swap
, "%*s%s\t%u\t%u\t%d\n",
2749 len
< 40 ? 40 - len
: 1, " ",
2750 S_ISBLK(file_inode(file
)->i_mode
) ?
2751 "partition" : "file\t",
2752 si
->pages
<< (PAGE_SHIFT
- 10),
2753 si
->inuse_pages
<< (PAGE_SHIFT
- 10),
2758 static const struct seq_operations swaps_op
= {
2759 .start
= swap_start
,
2765 static int swaps_open(struct inode
*inode
, struct file
*file
)
2767 struct seq_file
*seq
;
2770 ret
= seq_open(file
, &swaps_op
);
2774 seq
= file
->private_data
;
2775 seq
->poll_event
= atomic_read(&proc_poll_event
);
2779 static const struct proc_ops swaps_proc_ops
= {
2780 .proc_flags
= PROC_ENTRY_PERMANENT
,
2781 .proc_open
= swaps_open
,
2782 .proc_read
= seq_read
,
2783 .proc_lseek
= seq_lseek
,
2784 .proc_release
= seq_release
,
2785 .proc_poll
= swaps_poll
,
2788 static int __init
procswaps_init(void)
2790 proc_create("swaps", 0, NULL
, &swaps_proc_ops
);
2793 __initcall(procswaps_init
);
2794 #endif /* CONFIG_PROC_FS */
2796 #ifdef MAX_SWAPFILES_CHECK
2797 static int __init
max_swapfiles_check(void)
2799 MAX_SWAPFILES_CHECK();
2802 late_initcall(max_swapfiles_check
);
2805 static struct swap_info_struct
*alloc_swap_info(void)
2807 struct swap_info_struct
*p
;
2811 p
= kvzalloc(struct_size(p
, avail_lists
, nr_node_ids
), GFP_KERNEL
);
2813 return ERR_PTR(-ENOMEM
);
2815 spin_lock(&swap_lock
);
2816 for (type
= 0; type
< nr_swapfiles
; type
++) {
2817 if (!(swap_info
[type
]->flags
& SWP_USED
))
2820 if (type
>= MAX_SWAPFILES
) {
2821 spin_unlock(&swap_lock
);
2823 return ERR_PTR(-EPERM
);
2825 if (type
>= nr_swapfiles
) {
2827 WRITE_ONCE(swap_info
[type
], p
);
2829 * Write swap_info[type] before nr_swapfiles, in case a
2830 * racing procfs swap_start() or swap_next() is reading them.
2831 * (We never shrink nr_swapfiles, we never free this entry.)
2834 WRITE_ONCE(nr_swapfiles
, nr_swapfiles
+ 1);
2837 p
= swap_info
[type
];
2839 * Do not memset this entry: a racing procfs swap_next()
2840 * would be relying on p->type to remain valid.
2843 p
->swap_extent_root
= RB_ROOT
;
2844 plist_node_init(&p
->list
, 0);
2846 plist_node_init(&p
->avail_lists
[i
], 0);
2847 p
->flags
= SWP_USED
;
2848 spin_unlock(&swap_lock
);
2849 spin_lock_init(&p
->lock
);
2850 spin_lock_init(&p
->cont_lock
);
2855 static int claim_swapfile(struct swap_info_struct
*p
, struct inode
*inode
)
2859 if (S_ISBLK(inode
->i_mode
)) {
2860 p
->bdev
= bdgrab(I_BDEV(inode
));
2861 error
= blkdev_get(p
->bdev
,
2862 FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
, p
);
2867 p
->old_block_size
= block_size(p
->bdev
);
2868 error
= set_blocksize(p
->bdev
, PAGE_SIZE
);
2872 * Zoned block devices contain zones that have a sequential
2873 * write only restriction. Hence zoned block devices are not
2874 * suitable for swapping. Disallow them here.
2876 if (blk_queue_is_zoned(p
->bdev
->bd_queue
))
2878 p
->flags
|= SWP_BLKDEV
;
2879 } else if (S_ISREG(inode
->i_mode
)) {
2880 p
->bdev
= inode
->i_sb
->s_bdev
;
2888 * Find out how many pages are allowed for a single swap device. There
2889 * are two limiting factors:
2890 * 1) the number of bits for the swap offset in the swp_entry_t type, and
2891 * 2) the number of bits in the swap pte, as defined by the different
2894 * In order to find the largest possible bit mask, a swap entry with
2895 * swap type 0 and swap offset ~0UL is created, encoded to a swap pte,
2896 * decoded to a swp_entry_t again, and finally the swap offset is
2899 * This will mask all the bits from the initial ~0UL mask that can't
2900 * be encoded in either the swp_entry_t or the architecture definition
2903 unsigned long generic_max_swapfile_size(void)
2905 return swp_offset(pte_to_swp_entry(
2906 swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
2909 /* Can be overridden by an architecture for additional checks. */
2910 __weak
unsigned long max_swapfile_size(void)
2912 return generic_max_swapfile_size();
2915 static unsigned long read_swap_header(struct swap_info_struct
*p
,
2916 union swap_header
*swap_header
,
2917 struct inode
*inode
)
2920 unsigned long maxpages
;
2921 unsigned long swapfilepages
;
2922 unsigned long last_page
;
2924 if (memcmp("SWAPSPACE2", swap_header
->magic
.magic
, 10)) {
2925 pr_err("Unable to find swap-space signature\n");
2929 /* swap partition endianess hack... */
2930 if (swab32(swap_header
->info
.version
) == 1) {
2931 swab32s(&swap_header
->info
.version
);
2932 swab32s(&swap_header
->info
.last_page
);
2933 swab32s(&swap_header
->info
.nr_badpages
);
2934 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
2936 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++)
2937 swab32s(&swap_header
->info
.badpages
[i
]);
2939 /* Check the swap header's sub-version */
2940 if (swap_header
->info
.version
!= 1) {
2941 pr_warn("Unable to handle swap header version %d\n",
2942 swap_header
->info
.version
);
2947 p
->cluster_next
= 1;
2950 maxpages
= max_swapfile_size();
2951 last_page
= swap_header
->info
.last_page
;
2953 pr_warn("Empty swap-file\n");
2956 if (last_page
> maxpages
) {
2957 pr_warn("Truncating oversized swap area, only using %luk out of %luk\n",
2958 maxpages
<< (PAGE_SHIFT
- 10),
2959 last_page
<< (PAGE_SHIFT
- 10));
2961 if (maxpages
> last_page
) {
2962 maxpages
= last_page
+ 1;
2963 /* p->max is an unsigned int: don't overflow it */
2964 if ((unsigned int)maxpages
== 0)
2965 maxpages
= UINT_MAX
;
2967 p
->highest_bit
= maxpages
- 1;
2971 swapfilepages
= i_size_read(inode
) >> PAGE_SHIFT
;
2972 if (swapfilepages
&& maxpages
> swapfilepages
) {
2973 pr_warn("Swap area shorter than signature indicates\n");
2976 if (swap_header
->info
.nr_badpages
&& S_ISREG(inode
->i_mode
))
2978 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
2984 #define SWAP_CLUSTER_INFO_COLS \
2985 DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
2986 #define SWAP_CLUSTER_SPACE_COLS \
2987 DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
2988 #define SWAP_CLUSTER_COLS \
2989 max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
2991 static int setup_swap_map_and_extents(struct swap_info_struct
*p
,
2992 union swap_header
*swap_header
,
2993 unsigned char *swap_map
,
2994 struct swap_cluster_info
*cluster_info
,
2995 unsigned long maxpages
,
2999 unsigned int nr_good_pages
;
3001 unsigned long nr_clusters
= DIV_ROUND_UP(maxpages
, SWAPFILE_CLUSTER
);
3002 unsigned long col
= p
->cluster_next
/ SWAPFILE_CLUSTER
% SWAP_CLUSTER_COLS
;
3003 unsigned long i
, idx
;
3005 nr_good_pages
= maxpages
- 1; /* omit header page */
3007 cluster_list_init(&p
->free_clusters
);
3008 cluster_list_init(&p
->discard_clusters
);
3010 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++) {
3011 unsigned int page_nr
= swap_header
->info
.badpages
[i
];
3012 if (page_nr
== 0 || page_nr
> swap_header
->info
.last_page
)
3014 if (page_nr
< maxpages
) {
3015 swap_map
[page_nr
] = SWAP_MAP_BAD
;
3018 * Haven't marked the cluster free yet, no list
3019 * operation involved
3021 inc_cluster_info_page(p
, cluster_info
, page_nr
);
3025 /* Haven't marked the cluster free yet, no list operation involved */
3026 for (i
= maxpages
; i
< round_up(maxpages
, SWAPFILE_CLUSTER
); i
++)
3027 inc_cluster_info_page(p
, cluster_info
, i
);
3029 if (nr_good_pages
) {
3030 swap_map
[0] = SWAP_MAP_BAD
;
3032 * Not mark the cluster free yet, no list
3033 * operation involved
3035 inc_cluster_info_page(p
, cluster_info
, 0);
3037 p
->pages
= nr_good_pages
;
3038 nr_extents
= setup_swap_extents(p
, span
);
3041 nr_good_pages
= p
->pages
;
3043 if (!nr_good_pages
) {
3044 pr_warn("Empty swap-file\n");
3053 * Reduce false cache line sharing between cluster_info and
3054 * sharing same address space.
3056 for (k
= 0; k
< SWAP_CLUSTER_COLS
; k
++) {
3057 j
= (k
+ col
) % SWAP_CLUSTER_COLS
;
3058 for (i
= 0; i
< DIV_ROUND_UP(nr_clusters
, SWAP_CLUSTER_COLS
); i
++) {
3059 idx
= i
* SWAP_CLUSTER_COLS
+ j
;
3060 if (idx
>= nr_clusters
)
3062 if (cluster_count(&cluster_info
[idx
]))
3064 cluster_set_flag(&cluster_info
[idx
], CLUSTER_FLAG_FREE
);
3065 cluster_list_add_tail(&p
->free_clusters
, cluster_info
,
3073 * Helper to sys_swapon determining if a given swap
3074 * backing device queue supports DISCARD operations.
3076 static bool swap_discardable(struct swap_info_struct
*si
)
3078 struct request_queue
*q
= bdev_get_queue(si
->bdev
);
3080 if (!q
|| !blk_queue_discard(q
))
3086 SYSCALL_DEFINE2(swapon
, const char __user
*, specialfile
, int, swap_flags
)
3088 struct swap_info_struct
*p
;
3089 struct filename
*name
;
3090 struct file
*swap_file
= NULL
;
3091 struct address_space
*mapping
;
3094 union swap_header
*swap_header
;
3097 unsigned long maxpages
;
3098 unsigned char *swap_map
= NULL
;
3099 struct swap_cluster_info
*cluster_info
= NULL
;
3100 unsigned long *frontswap_map
= NULL
;
3101 struct page
*page
= NULL
;
3102 struct inode
*inode
= NULL
;
3103 bool inced_nr_rotate_swap
= false;
3105 if (swap_flags
& ~SWAP_FLAGS_VALID
)
3108 if (!capable(CAP_SYS_ADMIN
))
3111 if (!swap_avail_heads
)
3114 p
= alloc_swap_info();
3118 INIT_WORK(&p
->discard_work
, swap_discard_work
);
3120 name
= getname(specialfile
);
3122 error
= PTR_ERR(name
);
3126 swap_file
= file_open_name(name
, O_RDWR
|O_LARGEFILE
, 0);
3127 if (IS_ERR(swap_file
)) {
3128 error
= PTR_ERR(swap_file
);
3133 p
->swap_file
= swap_file
;
3134 mapping
= swap_file
->f_mapping
;
3135 inode
= mapping
->host
;
3137 error
= claim_swapfile(p
, inode
);
3138 if (unlikely(error
))
3142 if (IS_SWAPFILE(inode
)) {
3144 goto bad_swap_unlock_inode
;
3148 * Read the swap header.
3150 if (!mapping
->a_ops
->readpage
) {
3152 goto bad_swap_unlock_inode
;
3154 page
= read_mapping_page(mapping
, 0, swap_file
);
3156 error
= PTR_ERR(page
);
3157 goto bad_swap_unlock_inode
;
3159 swap_header
= kmap(page
);
3161 maxpages
= read_swap_header(p
, swap_header
, inode
);
3162 if (unlikely(!maxpages
)) {
3164 goto bad_swap_unlock_inode
;
3167 /* OK, set up the swap map and apply the bad block list */
3168 swap_map
= vzalloc(maxpages
);
3171 goto bad_swap_unlock_inode
;
3174 if (bdi_cap_stable_pages_required(inode_to_bdi(inode
)))
3175 p
->flags
|= SWP_STABLE_WRITES
;
3177 if (bdi_cap_synchronous_io(inode_to_bdi(inode
)))
3178 p
->flags
|= SWP_SYNCHRONOUS_IO
;
3180 if (p
->bdev
&& blk_queue_nonrot(bdev_get_queue(p
->bdev
))) {
3182 unsigned long ci
, nr_cluster
;
3184 p
->flags
|= SWP_SOLIDSTATE
;
3186 * select a random position to start with to help wear leveling
3189 p
->cluster_next
= 1 + (prandom_u32() % p
->highest_bit
);
3190 nr_cluster
= DIV_ROUND_UP(maxpages
, SWAPFILE_CLUSTER
);
3192 cluster_info
= kvcalloc(nr_cluster
, sizeof(*cluster_info
),
3194 if (!cluster_info
) {
3196 goto bad_swap_unlock_inode
;
3199 for (ci
= 0; ci
< nr_cluster
; ci
++)
3200 spin_lock_init(&((cluster_info
+ ci
)->lock
));
3202 p
->percpu_cluster
= alloc_percpu(struct percpu_cluster
);
3203 if (!p
->percpu_cluster
) {
3205 goto bad_swap_unlock_inode
;
3207 for_each_possible_cpu(cpu
) {
3208 struct percpu_cluster
*cluster
;
3209 cluster
= per_cpu_ptr(p
->percpu_cluster
, cpu
);
3210 cluster_set_null(&cluster
->index
);
3213 atomic_inc(&nr_rotate_swap
);
3214 inced_nr_rotate_swap
= true;
3217 error
= swap_cgroup_swapon(p
->type
, maxpages
);
3219 goto bad_swap_unlock_inode
;
3221 nr_extents
= setup_swap_map_and_extents(p
, swap_header
, swap_map
,
3222 cluster_info
, maxpages
, &span
);
3223 if (unlikely(nr_extents
< 0)) {
3225 goto bad_swap_unlock_inode
;
3227 /* frontswap enabled? set up bit-per-page map for frontswap */
3228 if (IS_ENABLED(CONFIG_FRONTSWAP
))
3229 frontswap_map
= kvcalloc(BITS_TO_LONGS(maxpages
),
3233 if (p
->bdev
&&(swap_flags
& SWAP_FLAG_DISCARD
) && swap_discardable(p
)) {
3235 * When discard is enabled for swap with no particular
3236 * policy flagged, we set all swap discard flags here in
3237 * order to sustain backward compatibility with older
3238 * swapon(8) releases.
3240 p
->flags
|= (SWP_DISCARDABLE
| SWP_AREA_DISCARD
|
3244 * By flagging sys_swapon, a sysadmin can tell us to
3245 * either do single-time area discards only, or to just
3246 * perform discards for released swap page-clusters.
3247 * Now it's time to adjust the p->flags accordingly.
3249 if (swap_flags
& SWAP_FLAG_DISCARD_ONCE
)
3250 p
->flags
&= ~SWP_PAGE_DISCARD
;
3251 else if (swap_flags
& SWAP_FLAG_DISCARD_PAGES
)
3252 p
->flags
&= ~SWP_AREA_DISCARD
;
3254 /* issue a swapon-time discard if it's still required */
3255 if (p
->flags
& SWP_AREA_DISCARD
) {
3256 int err
= discard_swap(p
);
3258 pr_err("swapon: discard_swap(%p): %d\n",
3263 error
= init_swap_address_space(p
->type
, maxpages
);
3265 goto bad_swap_unlock_inode
;
3268 * Flush any pending IO and dirty mappings before we start using this
3271 inode
->i_flags
|= S_SWAPFILE
;
3272 error
= inode_drain_writes(inode
);
3274 inode
->i_flags
&= ~S_SWAPFILE
;
3275 goto bad_swap_unlock_inode
;
3278 mutex_lock(&swapon_mutex
);
3280 if (swap_flags
& SWAP_FLAG_PREFER
)
3282 (swap_flags
& SWAP_FLAG_PRIO_MASK
) >> SWAP_FLAG_PRIO_SHIFT
;
3283 enable_swap_info(p
, prio
, swap_map
, cluster_info
, frontswap_map
);
3285 pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
3286 p
->pages
<<(PAGE_SHIFT
-10), name
->name
, p
->prio
,
3287 nr_extents
, (unsigned long long)span
<<(PAGE_SHIFT
-10),
3288 (p
->flags
& SWP_SOLIDSTATE
) ? "SS" : "",
3289 (p
->flags
& SWP_DISCARDABLE
) ? "D" : "",
3290 (p
->flags
& SWP_AREA_DISCARD
) ? "s" : "",
3291 (p
->flags
& SWP_PAGE_DISCARD
) ? "c" : "",
3292 (frontswap_map
) ? "FS" : "");
3294 mutex_unlock(&swapon_mutex
);
3295 atomic_inc(&proc_poll_event
);
3296 wake_up_interruptible(&proc_poll_wait
);
3300 bad_swap_unlock_inode
:
3301 inode_unlock(inode
);
3303 free_percpu(p
->percpu_cluster
);
3304 p
->percpu_cluster
= NULL
;
3305 if (inode
&& S_ISBLK(inode
->i_mode
) && p
->bdev
) {
3306 set_blocksize(p
->bdev
, p
->old_block_size
);
3307 blkdev_put(p
->bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
3310 destroy_swap_extents(p
);
3311 swap_cgroup_swapoff(p
->type
);
3312 spin_lock(&swap_lock
);
3313 p
->swap_file
= NULL
;
3315 spin_unlock(&swap_lock
);
3317 kvfree(cluster_info
);
3318 kvfree(frontswap_map
);
3319 if (inced_nr_rotate_swap
)
3320 atomic_dec(&nr_rotate_swap
);
3322 filp_close(swap_file
, NULL
);
3324 if (page
&& !IS_ERR(page
)) {
3331 inode_unlock(inode
);
3333 enable_swap_slots_cache();
3337 void si_swapinfo(struct sysinfo
*val
)
3340 unsigned long nr_to_be_unused
= 0;
3342 spin_lock(&swap_lock
);
3343 for (type
= 0; type
< nr_swapfiles
; type
++) {
3344 struct swap_info_struct
*si
= swap_info
[type
];
3346 if ((si
->flags
& SWP_USED
) && !(si
->flags
& SWP_WRITEOK
))
3347 nr_to_be_unused
+= si
->inuse_pages
;
3349 val
->freeswap
= atomic_long_read(&nr_swap_pages
) + nr_to_be_unused
;
3350 val
->totalswap
= total_swap_pages
+ nr_to_be_unused
;
3351 spin_unlock(&swap_lock
);
3355 * Verify that a swap entry is valid and increment its swap map count.
3357 * Returns error code in following case.
3359 * - swp_entry is invalid -> EINVAL
3360 * - swp_entry is migration entry -> EINVAL
3361 * - swap-cache reference is requested but there is already one. -> EEXIST
3362 * - swap-cache reference is requested but the entry is not used. -> ENOENT
3363 * - swap-mapped reference requested but needs continued swap count. -> ENOMEM
3365 static int __swap_duplicate(swp_entry_t entry
, unsigned char usage
)
3367 struct swap_info_struct
*p
;
3368 struct swap_cluster_info
*ci
;
3369 unsigned long offset
;
3370 unsigned char count
;
3371 unsigned char has_cache
;
3374 p
= get_swap_device(entry
);
3378 offset
= swp_offset(entry
);
3379 ci
= lock_cluster_or_swap_info(p
, offset
);
3381 count
= p
->swap_map
[offset
];
3384 * swapin_readahead() doesn't check if a swap entry is valid, so the
3385 * swap entry could be SWAP_MAP_BAD. Check here with lock held.
3387 if (unlikely(swap_count(count
) == SWAP_MAP_BAD
)) {
3392 has_cache
= count
& SWAP_HAS_CACHE
;
3393 count
&= ~SWAP_HAS_CACHE
;
3396 if (usage
== SWAP_HAS_CACHE
) {
3398 /* set SWAP_HAS_CACHE if there is no cache and entry is used */
3399 if (!has_cache
&& count
)
3400 has_cache
= SWAP_HAS_CACHE
;
3401 else if (has_cache
) /* someone else added cache */
3403 else /* no users remaining */
3406 } else if (count
|| has_cache
) {
3408 if ((count
& ~COUNT_CONTINUED
) < SWAP_MAP_MAX
)
3410 else if ((count
& ~COUNT_CONTINUED
) > SWAP_MAP_MAX
)
3412 else if (swap_count_continued(p
, offset
, count
))
3413 count
= COUNT_CONTINUED
;
3417 err
= -ENOENT
; /* unused swap entry */
3419 p
->swap_map
[offset
] = count
| has_cache
;
3422 unlock_cluster_or_swap_info(p
, ci
);
3430 * Help swapoff by noting that swap entry belongs to shmem/tmpfs
3431 * (in which case its reference count is never incremented).
3433 void swap_shmem_alloc(swp_entry_t entry
)
3435 __swap_duplicate(entry
, SWAP_MAP_SHMEM
);
3439 * Increase reference count of swap entry by 1.
3440 * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
3441 * but could not be atomically allocated. Returns 0, just as if it succeeded,
3442 * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
3443 * might occur if a page table entry has got corrupted.
3445 int swap_duplicate(swp_entry_t entry
)
3449 while (!err
&& __swap_duplicate(entry
, 1) == -ENOMEM
)
3450 err
= add_swap_count_continuation(entry
, GFP_ATOMIC
);
3455 * @entry: swap entry for which we allocate swap cache.
3457 * Called when allocating swap cache for existing swap entry,
3458 * This can return error codes. Returns 0 at success.
3459 * -EEXIST means there is a swap cache.
3460 * Note: return code is different from swap_duplicate().
3462 int swapcache_prepare(swp_entry_t entry
)
3464 return __swap_duplicate(entry
, SWAP_HAS_CACHE
);
3467 struct swap_info_struct
*swp_swap_info(swp_entry_t entry
)
3469 return swap_type_to_swap_info(swp_type(entry
));
3472 struct swap_info_struct
*page_swap_info(struct page
*page
)
3474 swp_entry_t entry
= { .val
= page_private(page
) };
3475 return swp_swap_info(entry
);
3479 * out-of-line __page_file_ methods to avoid include hell.
3481 struct address_space
*__page_file_mapping(struct page
*page
)
3483 return page_swap_info(page
)->swap_file
->f_mapping
;
3485 EXPORT_SYMBOL_GPL(__page_file_mapping
);
3487 pgoff_t
__page_file_index(struct page
*page
)
3489 swp_entry_t swap
= { .val
= page_private(page
) };
3490 return swp_offset(swap
);
3492 EXPORT_SYMBOL_GPL(__page_file_index
);
3495 * add_swap_count_continuation - called when a swap count is duplicated
3496 * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
3497 * page of the original vmalloc'ed swap_map, to hold the continuation count
3498 * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called
3499 * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
3501 * These continuation pages are seldom referenced: the common paths all work
3502 * on the original swap_map, only referring to a continuation page when the
3503 * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
3505 * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
3506 * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
3507 * can be called after dropping locks.
3509 int add_swap_count_continuation(swp_entry_t entry
, gfp_t gfp_mask
)
3511 struct swap_info_struct
*si
;
3512 struct swap_cluster_info
*ci
;
3515 struct page
*list_page
;
3517 unsigned char count
;
3521 * When debugging, it's easier to use __GFP_ZERO here; but it's better
3522 * for latency not to zero a page while GFP_ATOMIC and holding locks.
3524 page
= alloc_page(gfp_mask
| __GFP_HIGHMEM
);
3526 si
= get_swap_device(entry
);
3529 * An acceptable race has occurred since the failing
3530 * __swap_duplicate(): the swap device may be swapoff
3534 spin_lock(&si
->lock
);
3536 offset
= swp_offset(entry
);
3538 ci
= lock_cluster(si
, offset
);
3540 count
= si
->swap_map
[offset
] & ~SWAP_HAS_CACHE
;
3542 if ((count
& ~COUNT_CONTINUED
) != SWAP_MAP_MAX
) {
3544 * The higher the swap count, the more likely it is that tasks
3545 * will race to add swap count continuation: we need to avoid
3546 * over-provisioning.
3557 * We are fortunate that although vmalloc_to_page uses pte_offset_map,
3558 * no architecture is using highmem pages for kernel page tables: so it
3559 * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps.
3561 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3562 offset
&= ~PAGE_MASK
;
3564 spin_lock(&si
->cont_lock
);
3566 * Page allocation does not initialize the page's lru field,
3567 * but it does always reset its private field.
3569 if (!page_private(head
)) {
3570 BUG_ON(count
& COUNT_CONTINUED
);
3571 INIT_LIST_HEAD(&head
->lru
);
3572 set_page_private(head
, SWP_CONTINUED
);
3573 si
->flags
|= SWP_CONTINUED
;
3576 list_for_each_entry(list_page
, &head
->lru
, lru
) {
3580 * If the previous map said no continuation, but we've found
3581 * a continuation page, free our allocation and use this one.
3583 if (!(count
& COUNT_CONTINUED
))
3584 goto out_unlock_cont
;
3586 map
= kmap_atomic(list_page
) + offset
;
3591 * If this continuation count now has some space in it,
3592 * free our allocation and use this one.
3594 if ((count
& ~COUNT_CONTINUED
) != SWAP_CONT_MAX
)
3595 goto out_unlock_cont
;
3598 list_add_tail(&page
->lru
, &head
->lru
);
3599 page
= NULL
; /* now it's attached, don't free it */
3601 spin_unlock(&si
->cont_lock
);
3604 spin_unlock(&si
->lock
);
3605 put_swap_device(si
);
3613 * swap_count_continued - when the original swap_map count is incremented
3614 * from SWAP_MAP_MAX, check if there is already a continuation page to carry
3615 * into, carry if so, or else fail until a new continuation page is allocated;
3616 * when the original swap_map count is decremented from 0 with continuation,
3617 * borrow from the continuation and report whether it still holds more.
3618 * Called while __swap_duplicate() or swap_entry_free() holds swap or cluster
3621 static bool swap_count_continued(struct swap_info_struct
*si
,
3622 pgoff_t offset
, unsigned char count
)
3629 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3630 if (page_private(head
) != SWP_CONTINUED
) {
3631 BUG_ON(count
& COUNT_CONTINUED
);
3632 return false; /* need to add count continuation */
3635 spin_lock(&si
->cont_lock
);
3636 offset
&= ~PAGE_MASK
;
3637 page
= list_next_entry(head
, lru
);
3638 map
= kmap_atomic(page
) + offset
;
3640 if (count
== SWAP_MAP_MAX
) /* initial increment from swap_map */
3641 goto init_map
; /* jump over SWAP_CONT_MAX checks */
3643 if (count
== (SWAP_MAP_MAX
| COUNT_CONTINUED
)) { /* incrementing */
3645 * Think of how you add 1 to 999
3647 while (*map
== (SWAP_CONT_MAX
| COUNT_CONTINUED
)) {
3649 page
= list_next_entry(page
, lru
);
3650 BUG_ON(page
== head
);
3651 map
= kmap_atomic(page
) + offset
;
3653 if (*map
== SWAP_CONT_MAX
) {
3655 page
= list_next_entry(page
, lru
);
3657 ret
= false; /* add count continuation */
3660 map
= kmap_atomic(page
) + offset
;
3661 init_map
: *map
= 0; /* we didn't zero the page */
3665 while ((page
= list_prev_entry(page
, lru
)) != head
) {
3666 map
= kmap_atomic(page
) + offset
;
3667 *map
= COUNT_CONTINUED
;
3670 ret
= true; /* incremented */
3672 } else { /* decrementing */
3674 * Think of how you subtract 1 from 1000
3676 BUG_ON(count
!= COUNT_CONTINUED
);
3677 while (*map
== COUNT_CONTINUED
) {
3679 page
= list_next_entry(page
, lru
);
3680 BUG_ON(page
== head
);
3681 map
= kmap_atomic(page
) + offset
;
3688 while ((page
= list_prev_entry(page
, lru
)) != head
) {
3689 map
= kmap_atomic(page
) + offset
;
3690 *map
= SWAP_CONT_MAX
| count
;
3691 count
= COUNT_CONTINUED
;
3694 ret
= count
== COUNT_CONTINUED
;
3697 spin_unlock(&si
->cont_lock
);
3702 * free_swap_count_continuations - swapoff free all the continuation pages
3703 * appended to the swap_map, after swap_map is quiesced, before vfree'ing it.
3705 static void free_swap_count_continuations(struct swap_info_struct
*si
)
3709 for (offset
= 0; offset
< si
->max
; offset
+= PAGE_SIZE
) {
3711 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3712 if (page_private(head
)) {
3713 struct page
*page
, *next
;
3715 list_for_each_entry_safe(page
, next
, &head
->lru
, lru
) {
3716 list_del(&page
->lru
);
3723 #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
3724 void mem_cgroup_throttle_swaprate(struct mem_cgroup
*memcg
, int node
,
3727 struct swap_info_struct
*si
, *next
;
3728 if (!(gfp_mask
& __GFP_IO
) || !memcg
)
3731 if (!blk_cgroup_congested())
3735 * We've already scheduled a throttle, avoid taking the global swap
3738 if (current
->throttle_queue
)
3741 spin_lock(&swap_avail_lock
);
3742 plist_for_each_entry_safe(si
, next
, &swap_avail_heads
[node
],
3743 avail_lists
[node
]) {
3745 blkcg_schedule_throttle(bdev_get_queue(si
->bdev
),
3750 spin_unlock(&swap_avail_lock
);
3754 static int __init
swapfile_init(void)
3758 swap_avail_heads
= kmalloc_array(nr_node_ids
, sizeof(struct plist_head
),
3760 if (!swap_avail_heads
) {
3761 pr_emerg("Not enough memory for swap heads, swap is disabled\n");
3766 plist_head_init(&swap_avail_heads
[nid
]);
3770 subsys_initcall(swapfile_init
);