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 */
224 sector_t
swap_page_sector(struct page
*page
)
226 struct swap_info_struct
*sis
= page_swap_info(page
);
227 struct swap_extent
*se
;
231 offset
= __page_file_index(page
);
232 se
= offset_to_swap_extent(sis
, offset
);
233 sector
= se
->start_block
+ (offset
- se
->start_page
);
234 return sector
<< (PAGE_SHIFT
- 9);
238 * swap allocation tell device that a cluster of swap can now be discarded,
239 * to allow the swap device to optimize its wear-levelling.
241 static void discard_swap_cluster(struct swap_info_struct
*si
,
242 pgoff_t start_page
, pgoff_t nr_pages
)
244 struct swap_extent
*se
= offset_to_swap_extent(si
, start_page
);
247 pgoff_t offset
= start_page
- se
->start_page
;
248 sector_t start_block
= se
->start_block
+ offset
;
249 sector_t nr_blocks
= se
->nr_pages
- offset
;
251 if (nr_blocks
> nr_pages
)
252 nr_blocks
= nr_pages
;
253 start_page
+= nr_blocks
;
254 nr_pages
-= nr_blocks
;
256 start_block
<<= PAGE_SHIFT
- 9;
257 nr_blocks
<<= PAGE_SHIFT
- 9;
258 if (blkdev_issue_discard(si
->bdev
, start_block
,
259 nr_blocks
, GFP_NOIO
, 0))
266 #ifdef CONFIG_THP_SWAP
267 #define SWAPFILE_CLUSTER HPAGE_PMD_NR
269 #define swap_entry_size(size) (size)
271 #define SWAPFILE_CLUSTER 256
274 * Define swap_entry_size() as constant to let compiler to optimize
275 * out some code if !CONFIG_THP_SWAP
277 #define swap_entry_size(size) 1
279 #define LATENCY_LIMIT 256
281 static inline void cluster_set_flag(struct swap_cluster_info
*info
,
287 static inline unsigned int cluster_count(struct swap_cluster_info
*info
)
292 static inline void cluster_set_count(struct swap_cluster_info
*info
,
298 static inline void cluster_set_count_flag(struct swap_cluster_info
*info
,
299 unsigned int c
, unsigned int f
)
305 static inline unsigned int cluster_next(struct swap_cluster_info
*info
)
310 static inline void cluster_set_next(struct swap_cluster_info
*info
,
316 static inline void cluster_set_next_flag(struct swap_cluster_info
*info
,
317 unsigned int n
, unsigned int f
)
323 static inline bool cluster_is_free(struct swap_cluster_info
*info
)
325 return info
->flags
& CLUSTER_FLAG_FREE
;
328 static inline bool cluster_is_null(struct swap_cluster_info
*info
)
330 return info
->flags
& CLUSTER_FLAG_NEXT_NULL
;
333 static inline void cluster_set_null(struct swap_cluster_info
*info
)
335 info
->flags
= CLUSTER_FLAG_NEXT_NULL
;
339 static inline bool cluster_is_huge(struct swap_cluster_info
*info
)
341 if (IS_ENABLED(CONFIG_THP_SWAP
))
342 return info
->flags
& CLUSTER_FLAG_HUGE
;
346 static inline void cluster_clear_huge(struct swap_cluster_info
*info
)
348 info
->flags
&= ~CLUSTER_FLAG_HUGE
;
351 static inline struct swap_cluster_info
*lock_cluster(struct swap_info_struct
*si
,
352 unsigned long offset
)
354 struct swap_cluster_info
*ci
;
356 ci
= si
->cluster_info
;
358 ci
+= offset
/ SWAPFILE_CLUSTER
;
359 spin_lock(&ci
->lock
);
364 static inline void unlock_cluster(struct swap_cluster_info
*ci
)
367 spin_unlock(&ci
->lock
);
371 * Determine the locking method in use for this device. Return
372 * swap_cluster_info if SSD-style cluster-based locking is in place.
374 static inline struct swap_cluster_info
*lock_cluster_or_swap_info(
375 struct swap_info_struct
*si
, unsigned long offset
)
377 struct swap_cluster_info
*ci
;
379 /* Try to use fine-grained SSD-style locking if available: */
380 ci
= lock_cluster(si
, offset
);
381 /* Otherwise, fall back to traditional, coarse locking: */
383 spin_lock(&si
->lock
);
388 static inline void unlock_cluster_or_swap_info(struct swap_info_struct
*si
,
389 struct swap_cluster_info
*ci
)
394 spin_unlock(&si
->lock
);
397 static inline bool cluster_list_empty(struct swap_cluster_list
*list
)
399 return cluster_is_null(&list
->head
);
402 static inline unsigned int cluster_list_first(struct swap_cluster_list
*list
)
404 return cluster_next(&list
->head
);
407 static void cluster_list_init(struct swap_cluster_list
*list
)
409 cluster_set_null(&list
->head
);
410 cluster_set_null(&list
->tail
);
413 static void cluster_list_add_tail(struct swap_cluster_list
*list
,
414 struct swap_cluster_info
*ci
,
417 if (cluster_list_empty(list
)) {
418 cluster_set_next_flag(&list
->head
, idx
, 0);
419 cluster_set_next_flag(&list
->tail
, idx
, 0);
421 struct swap_cluster_info
*ci_tail
;
422 unsigned int tail
= cluster_next(&list
->tail
);
425 * Nested cluster lock, but both cluster locks are
426 * only acquired when we held swap_info_struct->lock
429 spin_lock_nested(&ci_tail
->lock
, SINGLE_DEPTH_NESTING
);
430 cluster_set_next(ci_tail
, idx
);
431 spin_unlock(&ci_tail
->lock
);
432 cluster_set_next_flag(&list
->tail
, idx
, 0);
436 static unsigned int cluster_list_del_first(struct swap_cluster_list
*list
,
437 struct swap_cluster_info
*ci
)
441 idx
= cluster_next(&list
->head
);
442 if (cluster_next(&list
->tail
) == idx
) {
443 cluster_set_null(&list
->head
);
444 cluster_set_null(&list
->tail
);
446 cluster_set_next_flag(&list
->head
,
447 cluster_next(&ci
[idx
]), 0);
452 /* Add a cluster to discard list and schedule it to do discard */
453 static void swap_cluster_schedule_discard(struct swap_info_struct
*si
,
457 * If scan_swap_map() can't find a free cluster, it will check
458 * si->swap_map directly. To make sure the discarding cluster isn't
459 * taken by scan_swap_map(), mark the swap entries bad (occupied). It
460 * will be cleared after discard
462 memset(si
->swap_map
+ idx
* SWAPFILE_CLUSTER
,
463 SWAP_MAP_BAD
, SWAPFILE_CLUSTER
);
465 cluster_list_add_tail(&si
->discard_clusters
, si
->cluster_info
, idx
);
467 schedule_work(&si
->discard_work
);
470 static void __free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
472 struct swap_cluster_info
*ci
= si
->cluster_info
;
474 cluster_set_flag(ci
+ idx
, CLUSTER_FLAG_FREE
);
475 cluster_list_add_tail(&si
->free_clusters
, ci
, idx
);
479 * Doing discard actually. After a cluster discard is finished, the cluster
480 * will be added to free cluster list. caller should hold si->lock.
482 static void swap_do_scheduled_discard(struct swap_info_struct
*si
)
484 struct swap_cluster_info
*info
, *ci
;
487 info
= si
->cluster_info
;
489 while (!cluster_list_empty(&si
->discard_clusters
)) {
490 idx
= cluster_list_del_first(&si
->discard_clusters
, info
);
491 spin_unlock(&si
->lock
);
493 discard_swap_cluster(si
, idx
* SWAPFILE_CLUSTER
,
496 spin_lock(&si
->lock
);
497 ci
= lock_cluster(si
, idx
* SWAPFILE_CLUSTER
);
498 __free_cluster(si
, idx
);
499 memset(si
->swap_map
+ idx
* SWAPFILE_CLUSTER
,
500 0, SWAPFILE_CLUSTER
);
505 static void swap_discard_work(struct work_struct
*work
)
507 struct swap_info_struct
*si
;
509 si
= container_of(work
, struct swap_info_struct
, discard_work
);
511 spin_lock(&si
->lock
);
512 swap_do_scheduled_discard(si
);
513 spin_unlock(&si
->lock
);
516 static void alloc_cluster(struct swap_info_struct
*si
, unsigned long idx
)
518 struct swap_cluster_info
*ci
= si
->cluster_info
;
520 VM_BUG_ON(cluster_list_first(&si
->free_clusters
) != idx
);
521 cluster_list_del_first(&si
->free_clusters
, ci
);
522 cluster_set_count_flag(ci
+ idx
, 0, 0);
525 static void free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
527 struct swap_cluster_info
*ci
= si
->cluster_info
+ idx
;
529 VM_BUG_ON(cluster_count(ci
) != 0);
531 * If the swap is discardable, prepare discard the cluster
532 * instead of free it immediately. The cluster will be freed
535 if ((si
->flags
& (SWP_WRITEOK
| SWP_PAGE_DISCARD
)) ==
536 (SWP_WRITEOK
| SWP_PAGE_DISCARD
)) {
537 swap_cluster_schedule_discard(si
, idx
);
541 __free_cluster(si
, idx
);
545 * The cluster corresponding to page_nr will be used. The cluster will be
546 * removed from free cluster list and its usage counter will be increased.
548 static void inc_cluster_info_page(struct swap_info_struct
*p
,
549 struct swap_cluster_info
*cluster_info
, unsigned long page_nr
)
551 unsigned long idx
= page_nr
/ SWAPFILE_CLUSTER
;
555 if (cluster_is_free(&cluster_info
[idx
]))
556 alloc_cluster(p
, idx
);
558 VM_BUG_ON(cluster_count(&cluster_info
[idx
]) >= SWAPFILE_CLUSTER
);
559 cluster_set_count(&cluster_info
[idx
],
560 cluster_count(&cluster_info
[idx
]) + 1);
564 * The cluster corresponding to page_nr decreases one usage. If the usage
565 * counter becomes 0, which means no page in the cluster is in using, we can
566 * optionally discard the cluster and add it to free cluster list.
568 static void dec_cluster_info_page(struct swap_info_struct
*p
,
569 struct swap_cluster_info
*cluster_info
, unsigned long page_nr
)
571 unsigned long idx
= page_nr
/ SWAPFILE_CLUSTER
;
576 VM_BUG_ON(cluster_count(&cluster_info
[idx
]) == 0);
577 cluster_set_count(&cluster_info
[idx
],
578 cluster_count(&cluster_info
[idx
]) - 1);
580 if (cluster_count(&cluster_info
[idx
]) == 0)
581 free_cluster(p
, idx
);
585 * It's possible scan_swap_map() uses a free cluster in the middle of free
586 * cluster list. Avoiding such abuse to avoid list corruption.
589 scan_swap_map_ssd_cluster_conflict(struct swap_info_struct
*si
,
590 unsigned long offset
)
592 struct percpu_cluster
*percpu_cluster
;
595 offset
/= SWAPFILE_CLUSTER
;
596 conflict
= !cluster_list_empty(&si
->free_clusters
) &&
597 offset
!= cluster_list_first(&si
->free_clusters
) &&
598 cluster_is_free(&si
->cluster_info
[offset
]);
603 percpu_cluster
= this_cpu_ptr(si
->percpu_cluster
);
604 cluster_set_null(&percpu_cluster
->index
);
609 * Try to get a swap entry from current cpu's swap entry pool (a cluster). This
610 * might involve allocating a new cluster for current CPU too.
612 static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct
*si
,
613 unsigned long *offset
, unsigned long *scan_base
)
615 struct percpu_cluster
*cluster
;
616 struct swap_cluster_info
*ci
;
618 unsigned long tmp
, max
;
621 cluster
= this_cpu_ptr(si
->percpu_cluster
);
622 if (cluster_is_null(&cluster
->index
)) {
623 if (!cluster_list_empty(&si
->free_clusters
)) {
624 cluster
->index
= si
->free_clusters
.head
;
625 cluster
->next
= cluster_next(&cluster
->index
) *
627 } else if (!cluster_list_empty(&si
->discard_clusters
)) {
629 * we don't have free cluster but have some clusters in
630 * discarding, do discard now and reclaim them
632 swap_do_scheduled_discard(si
);
633 *scan_base
= *offset
= si
->cluster_next
;
642 * Other CPUs can use our cluster if they can't find a free cluster,
643 * check if there is still free entry in the cluster
646 max
= min_t(unsigned long, si
->max
,
647 (cluster_next(&cluster
->index
) + 1) * SWAPFILE_CLUSTER
);
649 cluster_set_null(&cluster
->index
);
652 ci
= lock_cluster(si
, tmp
);
654 if (!si
->swap_map
[tmp
]) {
662 cluster_set_null(&cluster
->index
);
665 cluster
->next
= tmp
+ 1;
671 static void __del_from_avail_list(struct swap_info_struct
*p
)
676 plist_del(&p
->avail_lists
[nid
], &swap_avail_heads
[nid
]);
679 static void del_from_avail_list(struct swap_info_struct
*p
)
681 spin_lock(&swap_avail_lock
);
682 __del_from_avail_list(p
);
683 spin_unlock(&swap_avail_lock
);
686 static void swap_range_alloc(struct swap_info_struct
*si
, unsigned long offset
,
687 unsigned int nr_entries
)
689 unsigned int end
= offset
+ nr_entries
- 1;
691 if (offset
== si
->lowest_bit
)
692 si
->lowest_bit
+= nr_entries
;
693 if (end
== si
->highest_bit
)
694 si
->highest_bit
-= nr_entries
;
695 si
->inuse_pages
+= nr_entries
;
696 if (si
->inuse_pages
== si
->pages
) {
697 si
->lowest_bit
= si
->max
;
699 del_from_avail_list(si
);
703 static void add_to_avail_list(struct swap_info_struct
*p
)
707 spin_lock(&swap_avail_lock
);
709 WARN_ON(!plist_node_empty(&p
->avail_lists
[nid
]));
710 plist_add(&p
->avail_lists
[nid
], &swap_avail_heads
[nid
]);
712 spin_unlock(&swap_avail_lock
);
715 static void swap_range_free(struct swap_info_struct
*si
, unsigned long offset
,
716 unsigned int nr_entries
)
718 unsigned long end
= offset
+ nr_entries
- 1;
719 void (*swap_slot_free_notify
)(struct block_device
*, unsigned long);
721 if (offset
< si
->lowest_bit
)
722 si
->lowest_bit
= offset
;
723 if (end
> si
->highest_bit
) {
724 bool was_full
= !si
->highest_bit
;
726 si
->highest_bit
= end
;
727 if (was_full
&& (si
->flags
& SWP_WRITEOK
))
728 add_to_avail_list(si
);
730 atomic_long_add(nr_entries
, &nr_swap_pages
);
731 si
->inuse_pages
-= nr_entries
;
732 if (si
->flags
& SWP_BLKDEV
)
733 swap_slot_free_notify
=
734 si
->bdev
->bd_disk
->fops
->swap_slot_free_notify
;
736 swap_slot_free_notify
= NULL
;
737 while (offset
<= end
) {
738 frontswap_invalidate_page(si
->type
, offset
);
739 if (swap_slot_free_notify
)
740 swap_slot_free_notify(si
->bdev
, offset
);
745 static int scan_swap_map_slots(struct swap_info_struct
*si
,
746 unsigned char usage
, int nr
,
749 struct swap_cluster_info
*ci
;
750 unsigned long offset
;
751 unsigned long scan_base
;
752 unsigned long last_in_cluster
= 0;
753 int latency_ration
= LATENCY_LIMIT
;
760 * We try to cluster swap pages by allocating them sequentially
761 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
762 * way, however, we resort to first-free allocation, starting
763 * a new cluster. This prevents us from scattering swap pages
764 * all over the entire swap partition, so that we reduce
765 * overall disk seek times between swap pages. -- sct
766 * But we do now try to find an empty cluster. -Andrea
767 * And we let swap pages go all over an SSD partition. Hugh
770 si
->flags
+= SWP_SCANNING
;
771 scan_base
= offset
= si
->cluster_next
;
774 if (si
->cluster_info
) {
775 if (scan_swap_map_try_ssd_cluster(si
, &offset
, &scan_base
))
781 if (unlikely(!si
->cluster_nr
--)) {
782 if (si
->pages
- si
->inuse_pages
< SWAPFILE_CLUSTER
) {
783 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
787 spin_unlock(&si
->lock
);
790 * If seek is expensive, start searching for new cluster from
791 * start of partition, to minimize the span of allocated swap.
792 * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info
793 * case, just handled by scan_swap_map_try_ssd_cluster() above.
795 scan_base
= offset
= si
->lowest_bit
;
796 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
- 1;
798 /* Locate the first empty (unaligned) cluster */
799 for (; last_in_cluster
<= si
->highest_bit
; offset
++) {
800 if (si
->swap_map
[offset
])
801 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
;
802 else if (offset
== last_in_cluster
) {
803 spin_lock(&si
->lock
);
804 offset
-= SWAPFILE_CLUSTER
- 1;
805 si
->cluster_next
= offset
;
806 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
809 if (unlikely(--latency_ration
< 0)) {
811 latency_ration
= LATENCY_LIMIT
;
816 spin_lock(&si
->lock
);
817 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
821 if (si
->cluster_info
) {
822 while (scan_swap_map_ssd_cluster_conflict(si
, offset
)) {
823 /* take a break if we already got some slots */
826 if (!scan_swap_map_try_ssd_cluster(si
, &offset
,
831 if (!(si
->flags
& SWP_WRITEOK
))
833 if (!si
->highest_bit
)
835 if (offset
> si
->highest_bit
)
836 scan_base
= offset
= si
->lowest_bit
;
838 ci
= lock_cluster(si
, offset
);
839 /* reuse swap entry of cache-only swap if not busy. */
840 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
843 spin_unlock(&si
->lock
);
844 swap_was_freed
= __try_to_reclaim_swap(si
, offset
, TTRS_ANYWAY
);
845 spin_lock(&si
->lock
);
846 /* entry was freed successfully, try to use this again */
849 goto scan
; /* check next one */
852 if (si
->swap_map
[offset
]) {
859 si
->swap_map
[offset
] = usage
;
860 inc_cluster_info_page(si
, si
->cluster_info
, offset
);
863 swap_range_alloc(si
, offset
, 1);
864 si
->cluster_next
= offset
+ 1;
865 slots
[n_ret
++] = swp_entry(si
->type
, offset
);
867 /* got enough slots or reach max slots? */
868 if ((n_ret
== nr
) || (offset
>= si
->highest_bit
))
871 /* search for next available slot */
873 /* time to take a break? */
874 if (unlikely(--latency_ration
< 0)) {
877 spin_unlock(&si
->lock
);
879 spin_lock(&si
->lock
);
880 latency_ration
= LATENCY_LIMIT
;
883 /* try to get more slots in cluster */
884 if (si
->cluster_info
) {
885 if (scan_swap_map_try_ssd_cluster(si
, &offset
, &scan_base
))
893 /* non-ssd case, still more slots in cluster? */
894 if (si
->cluster_nr
&& !si
->swap_map
[offset
]) {
900 si
->flags
-= SWP_SCANNING
;
904 spin_unlock(&si
->lock
);
905 while (++offset
<= si
->highest_bit
) {
906 if (!si
->swap_map
[offset
]) {
907 spin_lock(&si
->lock
);
910 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
911 spin_lock(&si
->lock
);
914 if (unlikely(--latency_ration
< 0)) {
916 latency_ration
= LATENCY_LIMIT
;
919 offset
= si
->lowest_bit
;
920 while (offset
< scan_base
) {
921 if (!si
->swap_map
[offset
]) {
922 spin_lock(&si
->lock
);
925 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
926 spin_lock(&si
->lock
);
929 if (unlikely(--latency_ration
< 0)) {
931 latency_ration
= LATENCY_LIMIT
;
935 spin_lock(&si
->lock
);
938 si
->flags
-= SWP_SCANNING
;
942 static int swap_alloc_cluster(struct swap_info_struct
*si
, swp_entry_t
*slot
)
945 struct swap_cluster_info
*ci
;
946 unsigned long offset
, i
;
950 * Should not even be attempting cluster allocations when huge
951 * page swap is disabled. Warn and fail the allocation.
953 if (!IS_ENABLED(CONFIG_THP_SWAP
)) {
958 if (cluster_list_empty(&si
->free_clusters
))
961 idx
= cluster_list_first(&si
->free_clusters
);
962 offset
= idx
* SWAPFILE_CLUSTER
;
963 ci
= lock_cluster(si
, offset
);
964 alloc_cluster(si
, idx
);
965 cluster_set_count_flag(ci
, SWAPFILE_CLUSTER
, CLUSTER_FLAG_HUGE
);
967 map
= si
->swap_map
+ offset
;
968 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++)
969 map
[i
] = SWAP_HAS_CACHE
;
971 swap_range_alloc(si
, offset
, SWAPFILE_CLUSTER
);
972 *slot
= swp_entry(si
->type
, offset
);
977 static void swap_free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
979 unsigned long offset
= idx
* SWAPFILE_CLUSTER
;
980 struct swap_cluster_info
*ci
;
982 ci
= lock_cluster(si
, offset
);
983 memset(si
->swap_map
+ offset
, 0, SWAPFILE_CLUSTER
);
984 cluster_set_count_flag(ci
, 0, 0);
985 free_cluster(si
, idx
);
987 swap_range_free(si
, offset
, SWAPFILE_CLUSTER
);
990 static unsigned long scan_swap_map(struct swap_info_struct
*si
,
996 n_ret
= scan_swap_map_slots(si
, usage
, 1, &entry
);
999 return swp_offset(entry
);
1005 int get_swap_pages(int n_goal
, swp_entry_t swp_entries
[], int entry_size
)
1007 unsigned long size
= swap_entry_size(entry_size
);
1008 struct swap_info_struct
*si
, *next
;
1013 /* Only single cluster request supported */
1014 WARN_ON_ONCE(n_goal
> 1 && size
== SWAPFILE_CLUSTER
);
1016 avail_pgs
= atomic_long_read(&nr_swap_pages
) / size
;
1020 if (n_goal
> SWAP_BATCH
)
1021 n_goal
= SWAP_BATCH
;
1023 if (n_goal
> avail_pgs
)
1026 atomic_long_sub(n_goal
* size
, &nr_swap_pages
);
1028 spin_lock(&swap_avail_lock
);
1031 node
= numa_node_id();
1032 plist_for_each_entry_safe(si
, next
, &swap_avail_heads
[node
], avail_lists
[node
]) {
1033 /* requeue si to after same-priority siblings */
1034 plist_requeue(&si
->avail_lists
[node
], &swap_avail_heads
[node
]);
1035 spin_unlock(&swap_avail_lock
);
1036 spin_lock(&si
->lock
);
1037 if (!si
->highest_bit
|| !(si
->flags
& SWP_WRITEOK
)) {
1038 spin_lock(&swap_avail_lock
);
1039 if (plist_node_empty(&si
->avail_lists
[node
])) {
1040 spin_unlock(&si
->lock
);
1043 WARN(!si
->highest_bit
,
1044 "swap_info %d in list but !highest_bit\n",
1046 WARN(!(si
->flags
& SWP_WRITEOK
),
1047 "swap_info %d in list but !SWP_WRITEOK\n",
1049 __del_from_avail_list(si
);
1050 spin_unlock(&si
->lock
);
1053 if (size
== SWAPFILE_CLUSTER
) {
1054 if (si
->flags
& SWP_BLKDEV
)
1055 n_ret
= swap_alloc_cluster(si
, swp_entries
);
1057 n_ret
= scan_swap_map_slots(si
, SWAP_HAS_CACHE
,
1058 n_goal
, swp_entries
);
1059 spin_unlock(&si
->lock
);
1060 if (n_ret
|| size
== SWAPFILE_CLUSTER
)
1062 pr_debug("scan_swap_map of si %d failed to find offset\n",
1065 spin_lock(&swap_avail_lock
);
1068 * if we got here, it's likely that si was almost full before,
1069 * and since scan_swap_map() can drop the si->lock, multiple
1070 * callers probably all tried to get a page from the same si
1071 * and it filled up before we could get one; or, the si filled
1072 * up between us dropping swap_avail_lock and taking si->lock.
1073 * Since we dropped the swap_avail_lock, the swap_avail_head
1074 * list may have been modified; so if next is still in the
1075 * swap_avail_head list then try it, otherwise start over
1076 * if we have not gotten any slots.
1078 if (plist_node_empty(&next
->avail_lists
[node
]))
1082 spin_unlock(&swap_avail_lock
);
1086 atomic_long_add((long)(n_goal
- n_ret
) * size
,
1092 /* The only caller of this function is now suspend routine */
1093 swp_entry_t
get_swap_page_of_type(int type
)
1095 struct swap_info_struct
*si
= swap_type_to_swap_info(type
);
1101 spin_lock(&si
->lock
);
1102 if (si
->flags
& SWP_WRITEOK
) {
1103 atomic_long_dec(&nr_swap_pages
);
1104 /* This is called for allocating swap entry, not cache */
1105 offset
= scan_swap_map(si
, 1);
1107 spin_unlock(&si
->lock
);
1108 return swp_entry(type
, offset
);
1110 atomic_long_inc(&nr_swap_pages
);
1112 spin_unlock(&si
->lock
);
1114 return (swp_entry_t
) {0};
1117 static struct swap_info_struct
*__swap_info_get(swp_entry_t entry
)
1119 struct swap_info_struct
*p
;
1120 unsigned long offset
;
1124 p
= swp_swap_info(entry
);
1127 if (!(p
->flags
& SWP_USED
))
1129 offset
= swp_offset(entry
);
1130 if (offset
>= p
->max
)
1135 pr_err("swap_info_get: %s%08lx\n", Bad_offset
, entry
.val
);
1138 pr_err("swap_info_get: %s%08lx\n", Unused_file
, entry
.val
);
1141 pr_err("swap_info_get: %s%08lx\n", Bad_file
, entry
.val
);
1146 static struct swap_info_struct
*_swap_info_get(swp_entry_t entry
)
1148 struct swap_info_struct
*p
;
1150 p
= __swap_info_get(entry
);
1153 if (!p
->swap_map
[swp_offset(entry
)])
1158 pr_err("swap_info_get: %s%08lx\n", Unused_offset
, entry
.val
);
1164 static struct swap_info_struct
*swap_info_get(swp_entry_t entry
)
1166 struct swap_info_struct
*p
;
1168 p
= _swap_info_get(entry
);
1170 spin_lock(&p
->lock
);
1174 static struct swap_info_struct
*swap_info_get_cont(swp_entry_t entry
,
1175 struct swap_info_struct
*q
)
1177 struct swap_info_struct
*p
;
1179 p
= _swap_info_get(entry
);
1183 spin_unlock(&q
->lock
);
1185 spin_lock(&p
->lock
);
1190 static unsigned char __swap_entry_free_locked(struct swap_info_struct
*p
,
1191 unsigned long offset
,
1192 unsigned char usage
)
1194 unsigned char count
;
1195 unsigned char has_cache
;
1197 count
= p
->swap_map
[offset
];
1199 has_cache
= count
& SWAP_HAS_CACHE
;
1200 count
&= ~SWAP_HAS_CACHE
;
1202 if (usage
== SWAP_HAS_CACHE
) {
1203 VM_BUG_ON(!has_cache
);
1205 } else if (count
== SWAP_MAP_SHMEM
) {
1207 * Or we could insist on shmem.c using a special
1208 * swap_shmem_free() and free_shmem_swap_and_cache()...
1211 } else if ((count
& ~COUNT_CONTINUED
) <= SWAP_MAP_MAX
) {
1212 if (count
== COUNT_CONTINUED
) {
1213 if (swap_count_continued(p
, offset
, count
))
1214 count
= SWAP_MAP_MAX
| COUNT_CONTINUED
;
1216 count
= SWAP_MAP_MAX
;
1221 usage
= count
| has_cache
;
1222 p
->swap_map
[offset
] = usage
? : SWAP_HAS_CACHE
;
1228 * Check whether swap entry is valid in the swap device. If so,
1229 * return pointer to swap_info_struct, and keep the swap entry valid
1230 * via preventing the swap device from being swapoff, until
1231 * put_swap_device() is called. Otherwise return NULL.
1233 * The entirety of the RCU read critical section must come before the
1234 * return from or after the call to synchronize_rcu() in
1235 * enable_swap_info() or swapoff(). So if "si->flags & SWP_VALID" is
1236 * true, the si->map, si->cluster_info, etc. must be valid in the
1239 * Notice that swapoff or swapoff+swapon can still happen before the
1240 * rcu_read_lock() in get_swap_device() or after the rcu_read_unlock()
1241 * in put_swap_device() if there isn't any other way to prevent
1242 * swapoff, such as page lock, page table lock, etc. The caller must
1243 * be prepared for that. For example, the following situation is
1248 * ... swapoff+swapon
1249 * __read_swap_cache_async()
1250 * swapcache_prepare()
1251 * __swap_duplicate()
1253 * // verify PTE not changed
1255 * In __swap_duplicate(), the swap_map need to be checked before
1256 * changing partly because the specified swap entry may be for another
1257 * swap device which has been swapoff. And in do_swap_page(), after
1258 * the page is read from the swap device, the PTE is verified not
1259 * changed with the page table locked to check whether the swap device
1260 * has been swapoff or swapoff+swapon.
1262 struct swap_info_struct
*get_swap_device(swp_entry_t entry
)
1264 struct swap_info_struct
*si
;
1265 unsigned long offset
;
1269 si
= swp_swap_info(entry
);
1274 if (!(si
->flags
& SWP_VALID
))
1276 offset
= swp_offset(entry
);
1277 if (offset
>= si
->max
)
1282 pr_err("%s: %s%08lx\n", __func__
, Bad_file
, entry
.val
);
1290 static unsigned char __swap_entry_free(struct swap_info_struct
*p
,
1291 swp_entry_t entry
, unsigned char usage
)
1293 struct swap_cluster_info
*ci
;
1294 unsigned long offset
= swp_offset(entry
);
1296 ci
= lock_cluster_or_swap_info(p
, offset
);
1297 usage
= __swap_entry_free_locked(p
, offset
, usage
);
1298 unlock_cluster_or_swap_info(p
, ci
);
1300 free_swap_slot(entry
);
1305 static void swap_entry_free(struct swap_info_struct
*p
, swp_entry_t entry
)
1307 struct swap_cluster_info
*ci
;
1308 unsigned long offset
= swp_offset(entry
);
1309 unsigned char count
;
1311 ci
= lock_cluster(p
, offset
);
1312 count
= p
->swap_map
[offset
];
1313 VM_BUG_ON(count
!= SWAP_HAS_CACHE
);
1314 p
->swap_map
[offset
] = 0;
1315 dec_cluster_info_page(p
, p
->cluster_info
, offset
);
1318 mem_cgroup_uncharge_swap(entry
, 1);
1319 swap_range_free(p
, offset
, 1);
1323 * Caller has made sure that the swap device corresponding to entry
1324 * is still around or has not been recycled.
1326 void swap_free(swp_entry_t entry
)
1328 struct swap_info_struct
*p
;
1330 p
= _swap_info_get(entry
);
1332 __swap_entry_free(p
, entry
, 1);
1336 * Called after dropping swapcache to decrease refcnt to swap entries.
1338 void put_swap_page(struct page
*page
, swp_entry_t entry
)
1340 unsigned long offset
= swp_offset(entry
);
1341 unsigned long idx
= offset
/ SWAPFILE_CLUSTER
;
1342 struct swap_cluster_info
*ci
;
1343 struct swap_info_struct
*si
;
1345 unsigned int i
, free_entries
= 0;
1347 int size
= swap_entry_size(hpage_nr_pages(page
));
1349 si
= _swap_info_get(entry
);
1353 ci
= lock_cluster_or_swap_info(si
, offset
);
1354 if (size
== SWAPFILE_CLUSTER
) {
1355 VM_BUG_ON(!cluster_is_huge(ci
));
1356 map
= si
->swap_map
+ offset
;
1357 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++) {
1359 VM_BUG_ON(!(val
& SWAP_HAS_CACHE
));
1360 if (val
== SWAP_HAS_CACHE
)
1363 cluster_clear_huge(ci
);
1364 if (free_entries
== SWAPFILE_CLUSTER
) {
1365 unlock_cluster_or_swap_info(si
, ci
);
1366 spin_lock(&si
->lock
);
1367 mem_cgroup_uncharge_swap(entry
, SWAPFILE_CLUSTER
);
1368 swap_free_cluster(si
, idx
);
1369 spin_unlock(&si
->lock
);
1373 for (i
= 0; i
< size
; i
++, entry
.val
++) {
1374 if (!__swap_entry_free_locked(si
, offset
+ i
, SWAP_HAS_CACHE
)) {
1375 unlock_cluster_or_swap_info(si
, ci
);
1376 free_swap_slot(entry
);
1379 lock_cluster_or_swap_info(si
, offset
);
1382 unlock_cluster_or_swap_info(si
, ci
);
1385 #ifdef CONFIG_THP_SWAP
1386 int split_swap_cluster(swp_entry_t entry
)
1388 struct swap_info_struct
*si
;
1389 struct swap_cluster_info
*ci
;
1390 unsigned long offset
= swp_offset(entry
);
1392 si
= _swap_info_get(entry
);
1395 ci
= lock_cluster(si
, offset
);
1396 cluster_clear_huge(ci
);
1402 static int swp_entry_cmp(const void *ent1
, const void *ent2
)
1404 const swp_entry_t
*e1
= ent1
, *e2
= ent2
;
1406 return (int)swp_type(*e1
) - (int)swp_type(*e2
);
1409 void swapcache_free_entries(swp_entry_t
*entries
, int n
)
1411 struct swap_info_struct
*p
, *prev
;
1421 * Sort swap entries by swap device, so each lock is only taken once.
1422 * nr_swapfiles isn't absolutely correct, but the overhead of sort() is
1423 * so low that it isn't necessary to optimize further.
1425 if (nr_swapfiles
> 1)
1426 sort(entries
, n
, sizeof(entries
[0]), swp_entry_cmp
, NULL
);
1427 for (i
= 0; i
< n
; ++i
) {
1428 p
= swap_info_get_cont(entries
[i
], prev
);
1430 swap_entry_free(p
, entries
[i
]);
1434 spin_unlock(&p
->lock
);
1438 * How many references to page are currently swapped out?
1439 * This does not give an exact answer when swap count is continued,
1440 * but does include the high COUNT_CONTINUED flag to allow for that.
1442 int page_swapcount(struct page
*page
)
1445 struct swap_info_struct
*p
;
1446 struct swap_cluster_info
*ci
;
1448 unsigned long offset
;
1450 entry
.val
= page_private(page
);
1451 p
= _swap_info_get(entry
);
1453 offset
= swp_offset(entry
);
1454 ci
= lock_cluster_or_swap_info(p
, offset
);
1455 count
= swap_count(p
->swap_map
[offset
]);
1456 unlock_cluster_or_swap_info(p
, ci
);
1461 int __swap_count(swp_entry_t entry
)
1463 struct swap_info_struct
*si
;
1464 pgoff_t offset
= swp_offset(entry
);
1467 si
= get_swap_device(entry
);
1469 count
= swap_count(si
->swap_map
[offset
]);
1470 put_swap_device(si
);
1475 static int swap_swapcount(struct swap_info_struct
*si
, swp_entry_t entry
)
1478 pgoff_t offset
= swp_offset(entry
);
1479 struct swap_cluster_info
*ci
;
1481 ci
= lock_cluster_or_swap_info(si
, offset
);
1482 count
= swap_count(si
->swap_map
[offset
]);
1483 unlock_cluster_or_swap_info(si
, ci
);
1488 * How many references to @entry are currently swapped out?
1489 * This does not give an exact answer when swap count is continued,
1490 * but does include the high COUNT_CONTINUED flag to allow for that.
1492 int __swp_swapcount(swp_entry_t entry
)
1495 struct swap_info_struct
*si
;
1497 si
= get_swap_device(entry
);
1499 count
= swap_swapcount(si
, entry
);
1500 put_swap_device(si
);
1506 * How many references to @entry are currently swapped out?
1507 * This considers COUNT_CONTINUED so it returns exact answer.
1509 int swp_swapcount(swp_entry_t entry
)
1511 int count
, tmp_count
, n
;
1512 struct swap_info_struct
*p
;
1513 struct swap_cluster_info
*ci
;
1518 p
= _swap_info_get(entry
);
1522 offset
= swp_offset(entry
);
1524 ci
= lock_cluster_or_swap_info(p
, offset
);
1526 count
= swap_count(p
->swap_map
[offset
]);
1527 if (!(count
& COUNT_CONTINUED
))
1530 count
&= ~COUNT_CONTINUED
;
1531 n
= SWAP_MAP_MAX
+ 1;
1533 page
= vmalloc_to_page(p
->swap_map
+ offset
);
1534 offset
&= ~PAGE_MASK
;
1535 VM_BUG_ON(page_private(page
) != SWP_CONTINUED
);
1538 page
= list_next_entry(page
, lru
);
1539 map
= kmap_atomic(page
);
1540 tmp_count
= map
[offset
];
1543 count
+= (tmp_count
& ~COUNT_CONTINUED
) * n
;
1544 n
*= (SWAP_CONT_MAX
+ 1);
1545 } while (tmp_count
& COUNT_CONTINUED
);
1547 unlock_cluster_or_swap_info(p
, ci
);
1551 static bool swap_page_trans_huge_swapped(struct swap_info_struct
*si
,
1554 struct swap_cluster_info
*ci
;
1555 unsigned char *map
= si
->swap_map
;
1556 unsigned long roffset
= swp_offset(entry
);
1557 unsigned long offset
= round_down(roffset
, SWAPFILE_CLUSTER
);
1561 ci
= lock_cluster_or_swap_info(si
, offset
);
1562 if (!ci
|| !cluster_is_huge(ci
)) {
1563 if (swap_count(map
[roffset
]))
1567 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++) {
1568 if (swap_count(map
[offset
+ i
])) {
1574 unlock_cluster_or_swap_info(si
, ci
);
1578 static bool page_swapped(struct page
*page
)
1581 struct swap_info_struct
*si
;
1583 if (!IS_ENABLED(CONFIG_THP_SWAP
) || likely(!PageTransCompound(page
)))
1584 return page_swapcount(page
) != 0;
1586 page
= compound_head(page
);
1587 entry
.val
= page_private(page
);
1588 si
= _swap_info_get(entry
);
1590 return swap_page_trans_huge_swapped(si
, entry
);
1594 static int page_trans_huge_map_swapcount(struct page
*page
, int *total_mapcount
,
1595 int *total_swapcount
)
1597 int i
, map_swapcount
, _total_mapcount
, _total_swapcount
;
1598 unsigned long offset
= 0;
1599 struct swap_info_struct
*si
;
1600 struct swap_cluster_info
*ci
= NULL
;
1601 unsigned char *map
= NULL
;
1602 int mapcount
, swapcount
= 0;
1604 /* hugetlbfs shouldn't call it */
1605 VM_BUG_ON_PAGE(PageHuge(page
), page
);
1607 if (!IS_ENABLED(CONFIG_THP_SWAP
) || likely(!PageTransCompound(page
))) {
1608 mapcount
= page_trans_huge_mapcount(page
, total_mapcount
);
1609 if (PageSwapCache(page
))
1610 swapcount
= page_swapcount(page
);
1611 if (total_swapcount
)
1612 *total_swapcount
= swapcount
;
1613 return mapcount
+ swapcount
;
1616 page
= compound_head(page
);
1618 _total_mapcount
= _total_swapcount
= map_swapcount
= 0;
1619 if (PageSwapCache(page
)) {
1622 entry
.val
= page_private(page
);
1623 si
= _swap_info_get(entry
);
1626 offset
= swp_offset(entry
);
1630 ci
= lock_cluster(si
, offset
);
1631 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1632 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
1633 _total_mapcount
+= mapcount
;
1635 swapcount
= swap_count(map
[offset
+ i
]);
1636 _total_swapcount
+= swapcount
;
1638 map_swapcount
= max(map_swapcount
, mapcount
+ swapcount
);
1641 if (PageDoubleMap(page
)) {
1643 _total_mapcount
-= HPAGE_PMD_NR
;
1645 mapcount
= compound_mapcount(page
);
1646 map_swapcount
+= mapcount
;
1647 _total_mapcount
+= mapcount
;
1649 *total_mapcount
= _total_mapcount
;
1650 if (total_swapcount
)
1651 *total_swapcount
= _total_swapcount
;
1653 return map_swapcount
;
1657 * We can write to an anon page without COW if there are no other references
1658 * to it. And as a side-effect, free up its swap: because the old content
1659 * on disk will never be read, and seeking back there to write new content
1660 * later would only waste time away from clustering.
1662 * NOTE: total_map_swapcount should not be relied upon by the caller if
1663 * reuse_swap_page() returns false, but it may be always overwritten
1664 * (see the other implementation for CONFIG_SWAP=n).
1666 bool reuse_swap_page(struct page
*page
, int *total_map_swapcount
)
1668 int count
, total_mapcount
, total_swapcount
;
1670 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1671 if (unlikely(PageKsm(page
)))
1673 count
= page_trans_huge_map_swapcount(page
, &total_mapcount
,
1675 if (total_map_swapcount
)
1676 *total_map_swapcount
= total_mapcount
+ total_swapcount
;
1677 if (count
== 1 && PageSwapCache(page
) &&
1678 (likely(!PageTransCompound(page
)) ||
1679 /* The remaining swap count will be freed soon */
1680 total_swapcount
== page_swapcount(page
))) {
1681 if (!PageWriteback(page
)) {
1682 page
= compound_head(page
);
1683 delete_from_swap_cache(page
);
1687 struct swap_info_struct
*p
;
1689 entry
.val
= page_private(page
);
1690 p
= swap_info_get(entry
);
1691 if (p
->flags
& SWP_STABLE_WRITES
) {
1692 spin_unlock(&p
->lock
);
1695 spin_unlock(&p
->lock
);
1703 * If swap is getting full, or if there are no more mappings of this page,
1704 * then try_to_free_swap is called to free its swap space.
1706 int try_to_free_swap(struct page
*page
)
1708 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1710 if (!PageSwapCache(page
))
1712 if (PageWriteback(page
))
1714 if (page_swapped(page
))
1718 * Once hibernation has begun to create its image of memory,
1719 * there's a danger that one of the calls to try_to_free_swap()
1720 * - most probably a call from __try_to_reclaim_swap() while
1721 * hibernation is allocating its own swap pages for the image,
1722 * but conceivably even a call from memory reclaim - will free
1723 * the swap from a page which has already been recorded in the
1724 * image as a clean swapcache page, and then reuse its swap for
1725 * another page of the image. On waking from hibernation, the
1726 * original page might be freed under memory pressure, then
1727 * later read back in from swap, now with the wrong data.
1729 * Hibernation suspends storage while it is writing the image
1730 * to disk so check that here.
1732 if (pm_suspended_storage())
1735 page
= compound_head(page
);
1736 delete_from_swap_cache(page
);
1742 * Free the swap entry like above, but also try to
1743 * free the page cache entry if it is the last user.
1745 int free_swap_and_cache(swp_entry_t entry
)
1747 struct swap_info_struct
*p
;
1748 unsigned char count
;
1750 if (non_swap_entry(entry
))
1753 p
= _swap_info_get(entry
);
1755 count
= __swap_entry_free(p
, entry
, 1);
1756 if (count
== SWAP_HAS_CACHE
&&
1757 !swap_page_trans_huge_swapped(p
, entry
))
1758 __try_to_reclaim_swap(p
, swp_offset(entry
),
1759 TTRS_UNMAPPED
| TTRS_FULL
);
1764 #ifdef CONFIG_HIBERNATION
1766 * Find the swap type that corresponds to given device (if any).
1768 * @offset - number of the PAGE_SIZE-sized block of the device, starting
1769 * from 0, in which the swap header is expected to be located.
1771 * This is needed for the suspend to disk (aka swsusp).
1773 int swap_type_of(dev_t device
, sector_t offset
, struct block_device
**bdev_p
)
1775 struct block_device
*bdev
= NULL
;
1779 bdev
= bdget(device
);
1781 spin_lock(&swap_lock
);
1782 for (type
= 0; type
< nr_swapfiles
; type
++) {
1783 struct swap_info_struct
*sis
= swap_info
[type
];
1785 if (!(sis
->flags
& SWP_WRITEOK
))
1790 *bdev_p
= bdgrab(sis
->bdev
);
1792 spin_unlock(&swap_lock
);
1795 if (bdev
== sis
->bdev
) {
1796 struct swap_extent
*se
= first_se(sis
);
1798 if (se
->start_block
== offset
) {
1800 *bdev_p
= bdgrab(sis
->bdev
);
1802 spin_unlock(&swap_lock
);
1808 spin_unlock(&swap_lock
);
1816 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
1817 * corresponding to given index in swap_info (swap type).
1819 sector_t
swapdev_block(int type
, pgoff_t offset
)
1821 struct block_device
*bdev
;
1822 struct swap_info_struct
*si
= swap_type_to_swap_info(type
);
1824 if (!si
|| !(si
->flags
& SWP_WRITEOK
))
1826 return map_swap_entry(swp_entry(type
, offset
), &bdev
);
1830 * Return either the total number of swap pages of given type, or the number
1831 * of free pages of that type (depending on @free)
1833 * This is needed for software suspend
1835 unsigned int count_swap_pages(int type
, int free
)
1839 spin_lock(&swap_lock
);
1840 if ((unsigned int)type
< nr_swapfiles
) {
1841 struct swap_info_struct
*sis
= swap_info
[type
];
1843 spin_lock(&sis
->lock
);
1844 if (sis
->flags
& SWP_WRITEOK
) {
1847 n
-= sis
->inuse_pages
;
1849 spin_unlock(&sis
->lock
);
1851 spin_unlock(&swap_lock
);
1854 #endif /* CONFIG_HIBERNATION */
1856 static inline int pte_same_as_swp(pte_t pte
, pte_t swp_pte
)
1858 return pte_same(pte_swp_clear_soft_dirty(pte
), swp_pte
);
1862 * No need to decide whether this PTE shares the swap entry with others,
1863 * just let do_wp_page work it out if a write is requested later - to
1864 * force COW, vm_page_prot omits write permission from any private vma.
1866 static int unuse_pte(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1867 unsigned long addr
, swp_entry_t entry
, struct page
*page
)
1869 struct page
*swapcache
;
1870 struct mem_cgroup
*memcg
;
1876 page
= ksm_might_need_to_copy(page
, vma
, addr
);
1877 if (unlikely(!page
))
1880 if (mem_cgroup_try_charge(page
, vma
->vm_mm
, GFP_KERNEL
,
1886 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
1887 if (unlikely(!pte_same_as_swp(*pte
, swp_entry_to_pte(entry
)))) {
1888 mem_cgroup_cancel_charge(page
, memcg
, false);
1893 dec_mm_counter(vma
->vm_mm
, MM_SWAPENTS
);
1894 inc_mm_counter(vma
->vm_mm
, MM_ANONPAGES
);
1896 set_pte_at(vma
->vm_mm
, addr
, pte
,
1897 pte_mkold(mk_pte(page
, vma
->vm_page_prot
)));
1898 if (page
== swapcache
) {
1899 page_add_anon_rmap(page
, vma
, addr
, false);
1900 mem_cgroup_commit_charge(page
, memcg
, true, false);
1901 } else { /* ksm created a completely new copy */
1902 page_add_new_anon_rmap(page
, vma
, addr
, false);
1903 mem_cgroup_commit_charge(page
, memcg
, false, false);
1904 lru_cache_add_active_or_unevictable(page
, vma
);
1908 * Move the page to the active list so it is not
1909 * immediately swapped out again after swapon.
1911 activate_page(page
);
1913 pte_unmap_unlock(pte
, ptl
);
1915 if (page
!= swapcache
) {
1922 static int unuse_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1923 unsigned long addr
, unsigned long end
,
1924 unsigned int type
, bool frontswap
,
1925 unsigned long *fs_pages_to_unuse
)
1930 struct swap_info_struct
*si
;
1931 unsigned long offset
;
1933 volatile unsigned char *swap_map
;
1935 si
= swap_info
[type
];
1936 pte
= pte_offset_map(pmd
, addr
);
1938 struct vm_fault vmf
;
1940 if (!is_swap_pte(*pte
))
1943 entry
= pte_to_swp_entry(*pte
);
1944 if (swp_type(entry
) != type
)
1947 offset
= swp_offset(entry
);
1948 if (frontswap
&& !frontswap_test(si
, offset
))
1952 swap_map
= &si
->swap_map
[offset
];
1956 page
= swapin_readahead(entry
, GFP_HIGHUSER_MOVABLE
, &vmf
);
1958 if (*swap_map
== 0 || *swap_map
== SWAP_MAP_BAD
)
1964 wait_on_page_writeback(page
);
1965 ret
= unuse_pte(vma
, pmd
, addr
, entry
, page
);
1972 try_to_free_swap(page
);
1976 if (*fs_pages_to_unuse
&& !--(*fs_pages_to_unuse
)) {
1977 ret
= FRONTSWAP_PAGES_UNUSED
;
1981 pte
= pte_offset_map(pmd
, addr
);
1982 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
1990 static inline int unuse_pmd_range(struct vm_area_struct
*vma
, pud_t
*pud
,
1991 unsigned long addr
, unsigned long end
,
1992 unsigned int type
, bool frontswap
,
1993 unsigned long *fs_pages_to_unuse
)
1999 pmd
= pmd_offset(pud
, addr
);
2002 next
= pmd_addr_end(addr
, end
);
2003 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
2005 ret
= unuse_pte_range(vma
, pmd
, addr
, next
, type
,
2006 frontswap
, fs_pages_to_unuse
);
2009 } while (pmd
++, addr
= next
, addr
!= end
);
2013 static inline int unuse_pud_range(struct vm_area_struct
*vma
, p4d_t
*p4d
,
2014 unsigned long addr
, unsigned long end
,
2015 unsigned int type
, bool frontswap
,
2016 unsigned long *fs_pages_to_unuse
)
2022 pud
= pud_offset(p4d
, addr
);
2024 next
= pud_addr_end(addr
, end
);
2025 if (pud_none_or_clear_bad(pud
))
2027 ret
= unuse_pmd_range(vma
, pud
, addr
, next
, type
,
2028 frontswap
, fs_pages_to_unuse
);
2031 } while (pud
++, addr
= next
, addr
!= end
);
2035 static inline int unuse_p4d_range(struct vm_area_struct
*vma
, pgd_t
*pgd
,
2036 unsigned long addr
, unsigned long end
,
2037 unsigned int type
, bool frontswap
,
2038 unsigned long *fs_pages_to_unuse
)
2044 p4d
= p4d_offset(pgd
, addr
);
2046 next
= p4d_addr_end(addr
, end
);
2047 if (p4d_none_or_clear_bad(p4d
))
2049 ret
= unuse_pud_range(vma
, p4d
, addr
, next
, type
,
2050 frontswap
, fs_pages_to_unuse
);
2053 } while (p4d
++, addr
= next
, addr
!= end
);
2057 static int unuse_vma(struct vm_area_struct
*vma
, unsigned int type
,
2058 bool frontswap
, unsigned long *fs_pages_to_unuse
)
2061 unsigned long addr
, end
, next
;
2064 addr
= vma
->vm_start
;
2067 pgd
= pgd_offset(vma
->vm_mm
, addr
);
2069 next
= pgd_addr_end(addr
, end
);
2070 if (pgd_none_or_clear_bad(pgd
))
2072 ret
= unuse_p4d_range(vma
, pgd
, addr
, next
, type
,
2073 frontswap
, fs_pages_to_unuse
);
2076 } while (pgd
++, addr
= next
, addr
!= end
);
2080 static int unuse_mm(struct mm_struct
*mm
, unsigned int type
,
2081 bool frontswap
, unsigned long *fs_pages_to_unuse
)
2083 struct vm_area_struct
*vma
;
2086 down_read(&mm
->mmap_sem
);
2087 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2088 if (vma
->anon_vma
) {
2089 ret
= unuse_vma(vma
, type
, frontswap
,
2096 up_read(&mm
->mmap_sem
);
2101 * Scan swap_map (or frontswap_map if frontswap parameter is true)
2102 * from current position to next entry still in use. Return 0
2103 * if there are no inuse entries after prev till end of the map.
2105 static unsigned int find_next_to_unuse(struct swap_info_struct
*si
,
2106 unsigned int prev
, bool frontswap
)
2109 unsigned char count
;
2112 * No need for swap_lock here: we're just looking
2113 * for whether an entry is in use, not modifying it; false
2114 * hits are okay, and sys_swapoff() has already prevented new
2115 * allocations from this area (while holding swap_lock).
2117 for (i
= prev
+ 1; i
< si
->max
; i
++) {
2118 count
= READ_ONCE(si
->swap_map
[i
]);
2119 if (count
&& swap_count(count
) != SWAP_MAP_BAD
)
2120 if (!frontswap
|| frontswap_test(si
, i
))
2122 if ((i
% LATENCY_LIMIT
) == 0)
2133 * If the boolean frontswap is true, only unuse pages_to_unuse pages;
2134 * pages_to_unuse==0 means all pages; ignored if frontswap is false
2136 int try_to_unuse(unsigned int type
, bool frontswap
,
2137 unsigned long pages_to_unuse
)
2139 struct mm_struct
*prev_mm
;
2140 struct mm_struct
*mm
;
2141 struct list_head
*p
;
2143 struct swap_info_struct
*si
= swap_info
[type
];
2148 if (!READ_ONCE(si
->inuse_pages
))
2155 retval
= shmem_unuse(type
, frontswap
, &pages_to_unuse
);
2162 spin_lock(&mmlist_lock
);
2163 p
= &init_mm
.mmlist
;
2164 while (READ_ONCE(si
->inuse_pages
) &&
2165 !signal_pending(current
) &&
2166 (p
= p
->next
) != &init_mm
.mmlist
) {
2168 mm
= list_entry(p
, struct mm_struct
, mmlist
);
2169 if (!mmget_not_zero(mm
))
2171 spin_unlock(&mmlist_lock
);
2174 retval
= unuse_mm(mm
, type
, frontswap
, &pages_to_unuse
);
2182 * Make sure that we aren't completely killing
2183 * interactive performance.
2186 spin_lock(&mmlist_lock
);
2188 spin_unlock(&mmlist_lock
);
2193 while (READ_ONCE(si
->inuse_pages
) &&
2194 !signal_pending(current
) &&
2195 (i
= find_next_to_unuse(si
, i
, frontswap
)) != 0) {
2197 entry
= swp_entry(type
, i
);
2198 page
= find_get_page(swap_address_space(entry
), i
);
2203 * It is conceivable that a racing task removed this page from
2204 * swap cache just before we acquired the page lock. The page
2205 * might even be back in swap cache on another swap area. But
2206 * that is okay, try_to_free_swap() only removes stale pages.
2209 wait_on_page_writeback(page
);
2210 try_to_free_swap(page
);
2215 * For frontswap, we just need to unuse pages_to_unuse, if
2216 * it was specified. Need not check frontswap again here as
2217 * we already zeroed out pages_to_unuse if not frontswap.
2219 if (pages_to_unuse
&& --pages_to_unuse
== 0)
2224 * Lets check again to see if there are still swap entries in the map.
2225 * If yes, we would need to do retry the unuse logic again.
2226 * Under global memory pressure, swap entries can be reinserted back
2227 * into process space after the mmlist loop above passes over them.
2229 * Limit the number of retries? No: when mmget_not_zero() above fails,
2230 * that mm is likely to be freeing swap from exit_mmap(), which proceeds
2231 * at its own independent pace; and even shmem_writepage() could have
2232 * been preempted after get_swap_page(), temporarily hiding that swap.
2233 * It's easy and robust (though cpu-intensive) just to keep retrying.
2235 if (READ_ONCE(si
->inuse_pages
)) {
2236 if (!signal_pending(current
))
2241 return (retval
== FRONTSWAP_PAGES_UNUSED
) ? 0 : retval
;
2245 * After a successful try_to_unuse, if no swap is now in use, we know
2246 * we can empty the mmlist. swap_lock must be held on entry and exit.
2247 * Note that mmlist_lock nests inside swap_lock, and an mm must be
2248 * added to the mmlist just after page_duplicate - before would be racy.
2250 static void drain_mmlist(void)
2252 struct list_head
*p
, *next
;
2255 for (type
= 0; type
< nr_swapfiles
; type
++)
2256 if (swap_info
[type
]->inuse_pages
)
2258 spin_lock(&mmlist_lock
);
2259 list_for_each_safe(p
, next
, &init_mm
.mmlist
)
2261 spin_unlock(&mmlist_lock
);
2265 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
2266 * corresponds to page offset for the specified swap entry.
2267 * Note that the type of this function is sector_t, but it returns page offset
2268 * into the bdev, not sector offset.
2270 static sector_t
map_swap_entry(swp_entry_t entry
, struct block_device
**bdev
)
2272 struct swap_info_struct
*sis
;
2273 struct swap_extent
*se
;
2276 sis
= swp_swap_info(entry
);
2279 offset
= swp_offset(entry
);
2280 se
= offset_to_swap_extent(sis
, offset
);
2281 return se
->start_block
+ (offset
- se
->start_page
);
2285 * Returns the page offset into bdev for the specified page's swap entry.
2287 sector_t
map_swap_page(struct page
*page
, struct block_device
**bdev
)
2290 entry
.val
= page_private(page
);
2291 return map_swap_entry(entry
, bdev
);
2295 * Free all of a swapdev's extent information
2297 static void destroy_swap_extents(struct swap_info_struct
*sis
)
2299 while (!RB_EMPTY_ROOT(&sis
->swap_extent_root
)) {
2300 struct rb_node
*rb
= sis
->swap_extent_root
.rb_node
;
2301 struct swap_extent
*se
= rb_entry(rb
, struct swap_extent
, rb_node
);
2303 rb_erase(rb
, &sis
->swap_extent_root
);
2307 if (sis
->flags
& SWP_ACTIVATED
) {
2308 struct file
*swap_file
= sis
->swap_file
;
2309 struct address_space
*mapping
= swap_file
->f_mapping
;
2311 sis
->flags
&= ~SWP_ACTIVATED
;
2312 if (mapping
->a_ops
->swap_deactivate
)
2313 mapping
->a_ops
->swap_deactivate(swap_file
);
2318 * Add a block range (and the corresponding page range) into this swapdev's
2321 * This function rather assumes that it is called in ascending page order.
2324 add_swap_extent(struct swap_info_struct
*sis
, unsigned long start_page
,
2325 unsigned long nr_pages
, sector_t start_block
)
2327 struct rb_node
**link
= &sis
->swap_extent_root
.rb_node
, *parent
= NULL
;
2328 struct swap_extent
*se
;
2329 struct swap_extent
*new_se
;
2332 * place the new node at the right most since the
2333 * function is called in ascending page order.
2337 link
= &parent
->rb_right
;
2341 se
= rb_entry(parent
, struct swap_extent
, rb_node
);
2342 BUG_ON(se
->start_page
+ se
->nr_pages
!= start_page
);
2343 if (se
->start_block
+ se
->nr_pages
== start_block
) {
2345 se
->nr_pages
+= nr_pages
;
2350 /* No merge, insert a new extent. */
2351 new_se
= kmalloc(sizeof(*se
), GFP_KERNEL
);
2354 new_se
->start_page
= start_page
;
2355 new_se
->nr_pages
= nr_pages
;
2356 new_se
->start_block
= start_block
;
2358 rb_link_node(&new_se
->rb_node
, parent
, link
);
2359 rb_insert_color(&new_se
->rb_node
, &sis
->swap_extent_root
);
2362 EXPORT_SYMBOL_GPL(add_swap_extent
);
2365 * A `swap extent' is a simple thing which maps a contiguous range of pages
2366 * onto a contiguous range of disk blocks. An ordered list of swap extents
2367 * is built at swapon time and is then used at swap_writepage/swap_readpage
2368 * time for locating where on disk a page belongs.
2370 * If the swapfile is an S_ISBLK block device, a single extent is installed.
2371 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
2372 * swap files identically.
2374 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
2375 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
2376 * swapfiles are handled *identically* after swapon time.
2378 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
2379 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
2380 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
2381 * requirements, they are simply tossed out - we will never use those blocks
2384 * For all swap devices we set S_SWAPFILE across the life of the swapon. This
2385 * prevents users from writing to the swap device, which will corrupt memory.
2387 * The amount of disk space which a single swap extent represents varies.
2388 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
2389 * extents in the list. To avoid much list walking, we cache the previous
2390 * search location in `curr_swap_extent', and start new searches from there.
2391 * This is extremely effective. The average number of iterations in
2392 * map_swap_page() has been measured at about 0.3 per page. - akpm.
2394 static int setup_swap_extents(struct swap_info_struct
*sis
, sector_t
*span
)
2396 struct file
*swap_file
= sis
->swap_file
;
2397 struct address_space
*mapping
= swap_file
->f_mapping
;
2398 struct inode
*inode
= mapping
->host
;
2401 if (S_ISBLK(inode
->i_mode
)) {
2402 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
2407 if (mapping
->a_ops
->swap_activate
) {
2408 ret
= mapping
->a_ops
->swap_activate(sis
, swap_file
, span
);
2410 sis
->flags
|= SWP_ACTIVATED
;
2412 sis
->flags
|= SWP_FS
;
2413 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
2419 return generic_swapfile_activate(sis
, swap_file
, span
);
2422 static int swap_node(struct swap_info_struct
*p
)
2424 struct block_device
*bdev
;
2429 bdev
= p
->swap_file
->f_inode
->i_sb
->s_bdev
;
2431 return bdev
? bdev
->bd_disk
->node_id
: NUMA_NO_NODE
;
2434 static void setup_swap_info(struct swap_info_struct
*p
, int prio
,
2435 unsigned char *swap_map
,
2436 struct swap_cluster_info
*cluster_info
)
2443 p
->prio
= --least_priority
;
2445 * the plist prio is negated because plist ordering is
2446 * low-to-high, while swap ordering is high-to-low
2448 p
->list
.prio
= -p
->prio
;
2451 p
->avail_lists
[i
].prio
= -p
->prio
;
2453 if (swap_node(p
) == i
)
2454 p
->avail_lists
[i
].prio
= 1;
2456 p
->avail_lists
[i
].prio
= -p
->prio
;
2459 p
->swap_map
= swap_map
;
2460 p
->cluster_info
= cluster_info
;
2463 static void _enable_swap_info(struct swap_info_struct
*p
)
2465 p
->flags
|= SWP_WRITEOK
| SWP_VALID
;
2466 atomic_long_add(p
->pages
, &nr_swap_pages
);
2467 total_swap_pages
+= p
->pages
;
2469 assert_spin_locked(&swap_lock
);
2471 * both lists are plists, and thus priority ordered.
2472 * swap_active_head needs to be priority ordered for swapoff(),
2473 * which on removal of any swap_info_struct with an auto-assigned
2474 * (i.e. negative) priority increments the auto-assigned priority
2475 * of any lower-priority swap_info_structs.
2476 * swap_avail_head needs to be priority ordered for get_swap_page(),
2477 * which allocates swap pages from the highest available priority
2480 plist_add(&p
->list
, &swap_active_head
);
2481 add_to_avail_list(p
);
2484 static void enable_swap_info(struct swap_info_struct
*p
, int prio
,
2485 unsigned char *swap_map
,
2486 struct swap_cluster_info
*cluster_info
,
2487 unsigned long *frontswap_map
)
2489 frontswap_init(p
->type
, frontswap_map
);
2490 spin_lock(&swap_lock
);
2491 spin_lock(&p
->lock
);
2492 setup_swap_info(p
, prio
, swap_map
, cluster_info
);
2493 spin_unlock(&p
->lock
);
2494 spin_unlock(&swap_lock
);
2496 * Guarantee swap_map, cluster_info, etc. fields are valid
2497 * between get/put_swap_device() if SWP_VALID bit is set
2500 spin_lock(&swap_lock
);
2501 spin_lock(&p
->lock
);
2502 _enable_swap_info(p
);
2503 spin_unlock(&p
->lock
);
2504 spin_unlock(&swap_lock
);
2507 static void reinsert_swap_info(struct swap_info_struct
*p
)
2509 spin_lock(&swap_lock
);
2510 spin_lock(&p
->lock
);
2511 setup_swap_info(p
, p
->prio
, p
->swap_map
, p
->cluster_info
);
2512 _enable_swap_info(p
);
2513 spin_unlock(&p
->lock
);
2514 spin_unlock(&swap_lock
);
2517 bool has_usable_swap(void)
2521 spin_lock(&swap_lock
);
2522 if (plist_head_empty(&swap_active_head
))
2524 spin_unlock(&swap_lock
);
2528 SYSCALL_DEFINE1(swapoff
, const char __user
*, specialfile
)
2530 struct swap_info_struct
*p
= NULL
;
2531 unsigned char *swap_map
;
2532 struct swap_cluster_info
*cluster_info
;
2533 unsigned long *frontswap_map
;
2534 struct file
*swap_file
, *victim
;
2535 struct address_space
*mapping
;
2536 struct inode
*inode
;
2537 struct filename
*pathname
;
2539 unsigned int old_block_size
;
2541 if (!capable(CAP_SYS_ADMIN
))
2544 BUG_ON(!current
->mm
);
2546 pathname
= getname(specialfile
);
2547 if (IS_ERR(pathname
))
2548 return PTR_ERR(pathname
);
2550 victim
= file_open_name(pathname
, O_RDWR
|O_LARGEFILE
, 0);
2551 err
= PTR_ERR(victim
);
2555 mapping
= victim
->f_mapping
;
2556 spin_lock(&swap_lock
);
2557 plist_for_each_entry(p
, &swap_active_head
, list
) {
2558 if (p
->flags
& SWP_WRITEOK
) {
2559 if (p
->swap_file
->f_mapping
== mapping
) {
2567 spin_unlock(&swap_lock
);
2570 if (!security_vm_enough_memory_mm(current
->mm
, p
->pages
))
2571 vm_unacct_memory(p
->pages
);
2574 spin_unlock(&swap_lock
);
2577 del_from_avail_list(p
);
2578 spin_lock(&p
->lock
);
2580 struct swap_info_struct
*si
= p
;
2583 plist_for_each_entry_continue(si
, &swap_active_head
, list
) {
2586 for_each_node(nid
) {
2587 if (si
->avail_lists
[nid
].prio
!= 1)
2588 si
->avail_lists
[nid
].prio
--;
2593 plist_del(&p
->list
, &swap_active_head
);
2594 atomic_long_sub(p
->pages
, &nr_swap_pages
);
2595 total_swap_pages
-= p
->pages
;
2596 p
->flags
&= ~SWP_WRITEOK
;
2597 spin_unlock(&p
->lock
);
2598 spin_unlock(&swap_lock
);
2600 disable_swap_slots_cache_lock();
2602 set_current_oom_origin();
2603 err
= try_to_unuse(p
->type
, false, 0); /* force unuse all pages */
2604 clear_current_oom_origin();
2607 /* re-insert swap space back into swap_list */
2608 reinsert_swap_info(p
);
2609 reenable_swap_slots_cache_unlock();
2613 reenable_swap_slots_cache_unlock();
2615 spin_lock(&swap_lock
);
2616 spin_lock(&p
->lock
);
2617 p
->flags
&= ~SWP_VALID
; /* mark swap device as invalid */
2618 spin_unlock(&p
->lock
);
2619 spin_unlock(&swap_lock
);
2621 * wait for swap operations protected by get/put_swap_device()
2626 flush_work(&p
->discard_work
);
2628 destroy_swap_extents(p
);
2629 if (p
->flags
& SWP_CONTINUED
)
2630 free_swap_count_continuations(p
);
2632 if (!p
->bdev
|| !blk_queue_nonrot(bdev_get_queue(p
->bdev
)))
2633 atomic_dec(&nr_rotate_swap
);
2635 mutex_lock(&swapon_mutex
);
2636 spin_lock(&swap_lock
);
2637 spin_lock(&p
->lock
);
2640 /* wait for anyone still in scan_swap_map */
2641 p
->highest_bit
= 0; /* cuts scans short */
2642 while (p
->flags
>= SWP_SCANNING
) {
2643 spin_unlock(&p
->lock
);
2644 spin_unlock(&swap_lock
);
2645 schedule_timeout_uninterruptible(1);
2646 spin_lock(&swap_lock
);
2647 spin_lock(&p
->lock
);
2650 swap_file
= p
->swap_file
;
2651 old_block_size
= p
->old_block_size
;
2652 p
->swap_file
= NULL
;
2654 swap_map
= p
->swap_map
;
2656 cluster_info
= p
->cluster_info
;
2657 p
->cluster_info
= NULL
;
2658 frontswap_map
= frontswap_map_get(p
);
2659 spin_unlock(&p
->lock
);
2660 spin_unlock(&swap_lock
);
2661 frontswap_invalidate_area(p
->type
);
2662 frontswap_map_set(p
, NULL
);
2663 mutex_unlock(&swapon_mutex
);
2664 free_percpu(p
->percpu_cluster
);
2665 p
->percpu_cluster
= NULL
;
2667 kvfree(cluster_info
);
2668 kvfree(frontswap_map
);
2669 /* Destroy swap account information */
2670 swap_cgroup_swapoff(p
->type
);
2671 exit_swap_address_space(p
->type
);
2673 inode
= mapping
->host
;
2674 if (S_ISBLK(inode
->i_mode
)) {
2675 struct block_device
*bdev
= I_BDEV(inode
);
2677 set_blocksize(bdev
, old_block_size
);
2678 blkdev_put(bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
2682 inode
->i_flags
&= ~S_SWAPFILE
;
2683 inode_unlock(inode
);
2684 filp_close(swap_file
, NULL
);
2687 * Clear the SWP_USED flag after all resources are freed so that swapon
2688 * can reuse this swap_info in alloc_swap_info() safely. It is ok to
2689 * not hold p->lock after we cleared its SWP_WRITEOK.
2691 spin_lock(&swap_lock
);
2693 spin_unlock(&swap_lock
);
2696 atomic_inc(&proc_poll_event
);
2697 wake_up_interruptible(&proc_poll_wait
);
2700 filp_close(victim
, NULL
);
2706 #ifdef CONFIG_PROC_FS
2707 static __poll_t
swaps_poll(struct file
*file
, poll_table
*wait
)
2709 struct seq_file
*seq
= file
->private_data
;
2711 poll_wait(file
, &proc_poll_wait
, wait
);
2713 if (seq
->poll_event
!= atomic_read(&proc_poll_event
)) {
2714 seq
->poll_event
= atomic_read(&proc_poll_event
);
2715 return EPOLLIN
| EPOLLRDNORM
| EPOLLERR
| EPOLLPRI
;
2718 return EPOLLIN
| EPOLLRDNORM
;
2722 static void *swap_start(struct seq_file
*swap
, loff_t
*pos
)
2724 struct swap_info_struct
*si
;
2728 mutex_lock(&swapon_mutex
);
2731 return SEQ_START_TOKEN
;
2733 for (type
= 0; (si
= swap_type_to_swap_info(type
)); type
++) {
2734 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
2743 static void *swap_next(struct seq_file
*swap
, void *v
, loff_t
*pos
)
2745 struct swap_info_struct
*si
= v
;
2748 if (v
== SEQ_START_TOKEN
)
2751 type
= si
->type
+ 1;
2754 for (; (si
= swap_type_to_swap_info(type
)); type
++) {
2755 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
2763 static void swap_stop(struct seq_file
*swap
, void *v
)
2765 mutex_unlock(&swapon_mutex
);
2768 static int swap_show(struct seq_file
*swap
, void *v
)
2770 struct swap_info_struct
*si
= v
;
2774 if (si
== SEQ_START_TOKEN
) {
2775 seq_puts(swap
,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
2779 file
= si
->swap_file
;
2780 len
= seq_file_path(swap
, file
, " \t\n\\");
2781 seq_printf(swap
, "%*s%s\t%u\t%u\t%d\n",
2782 len
< 40 ? 40 - len
: 1, " ",
2783 S_ISBLK(file_inode(file
)->i_mode
) ?
2784 "partition" : "file\t",
2785 si
->pages
<< (PAGE_SHIFT
- 10),
2786 si
->inuse_pages
<< (PAGE_SHIFT
- 10),
2791 static const struct seq_operations swaps_op
= {
2792 .start
= swap_start
,
2798 static int swaps_open(struct inode
*inode
, struct file
*file
)
2800 struct seq_file
*seq
;
2803 ret
= seq_open(file
, &swaps_op
);
2807 seq
= file
->private_data
;
2808 seq
->poll_event
= atomic_read(&proc_poll_event
);
2812 static const struct file_operations proc_swaps_operations
= {
2815 .llseek
= seq_lseek
,
2816 .release
= seq_release
,
2820 static int __init
procswaps_init(void)
2822 proc_create("swaps", 0, NULL
, &proc_swaps_operations
);
2825 __initcall(procswaps_init
);
2826 #endif /* CONFIG_PROC_FS */
2828 #ifdef MAX_SWAPFILES_CHECK
2829 static int __init
max_swapfiles_check(void)
2831 MAX_SWAPFILES_CHECK();
2834 late_initcall(max_swapfiles_check
);
2837 static struct swap_info_struct
*alloc_swap_info(void)
2839 struct swap_info_struct
*p
;
2840 struct swap_info_struct
*defer
= NULL
;
2844 p
= kvzalloc(struct_size(p
, avail_lists
, nr_node_ids
), GFP_KERNEL
);
2846 return ERR_PTR(-ENOMEM
);
2848 spin_lock(&swap_lock
);
2849 for (type
= 0; type
< nr_swapfiles
; type
++) {
2850 if (!(swap_info
[type
]->flags
& SWP_USED
))
2853 if (type
>= MAX_SWAPFILES
) {
2854 spin_unlock(&swap_lock
);
2856 return ERR_PTR(-EPERM
);
2858 if (type
>= nr_swapfiles
) {
2860 WRITE_ONCE(swap_info
[type
], p
);
2862 * Write swap_info[type] before nr_swapfiles, in case a
2863 * racing procfs swap_start() or swap_next() is reading them.
2864 * (We never shrink nr_swapfiles, we never free this entry.)
2867 WRITE_ONCE(nr_swapfiles
, nr_swapfiles
+ 1);
2870 p
= swap_info
[type
];
2872 * Do not memset this entry: a racing procfs swap_next()
2873 * would be relying on p->type to remain valid.
2876 p
->swap_extent_root
= RB_ROOT
;
2877 plist_node_init(&p
->list
, 0);
2879 plist_node_init(&p
->avail_lists
[i
], 0);
2880 p
->flags
= SWP_USED
;
2881 spin_unlock(&swap_lock
);
2883 spin_lock_init(&p
->lock
);
2884 spin_lock_init(&p
->cont_lock
);
2889 static int claim_swapfile(struct swap_info_struct
*p
, struct inode
*inode
)
2893 if (S_ISBLK(inode
->i_mode
)) {
2894 p
->bdev
= bdgrab(I_BDEV(inode
));
2895 error
= blkdev_get(p
->bdev
,
2896 FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
, p
);
2901 p
->old_block_size
= block_size(p
->bdev
);
2902 error
= set_blocksize(p
->bdev
, PAGE_SIZE
);
2905 p
->flags
|= SWP_BLKDEV
;
2906 } else if (S_ISREG(inode
->i_mode
)) {
2907 p
->bdev
= inode
->i_sb
->s_bdev
;
2915 * Find out how many pages are allowed for a single swap device. There
2916 * are two limiting factors:
2917 * 1) the number of bits for the swap offset in the swp_entry_t type, and
2918 * 2) the number of bits in the swap pte, as defined by the different
2921 * In order to find the largest possible bit mask, a swap entry with
2922 * swap type 0 and swap offset ~0UL is created, encoded to a swap pte,
2923 * decoded to a swp_entry_t again, and finally the swap offset is
2926 * This will mask all the bits from the initial ~0UL mask that can't
2927 * be encoded in either the swp_entry_t or the architecture definition
2930 unsigned long generic_max_swapfile_size(void)
2932 return swp_offset(pte_to_swp_entry(
2933 swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
2936 /* Can be overridden by an architecture for additional checks. */
2937 __weak
unsigned long max_swapfile_size(void)
2939 return generic_max_swapfile_size();
2942 static unsigned long read_swap_header(struct swap_info_struct
*p
,
2943 union swap_header
*swap_header
,
2944 struct inode
*inode
)
2947 unsigned long maxpages
;
2948 unsigned long swapfilepages
;
2949 unsigned long last_page
;
2951 if (memcmp("SWAPSPACE2", swap_header
->magic
.magic
, 10)) {
2952 pr_err("Unable to find swap-space signature\n");
2956 /* swap partition endianess hack... */
2957 if (swab32(swap_header
->info
.version
) == 1) {
2958 swab32s(&swap_header
->info
.version
);
2959 swab32s(&swap_header
->info
.last_page
);
2960 swab32s(&swap_header
->info
.nr_badpages
);
2961 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
2963 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++)
2964 swab32s(&swap_header
->info
.badpages
[i
]);
2966 /* Check the swap header's sub-version */
2967 if (swap_header
->info
.version
!= 1) {
2968 pr_warn("Unable to handle swap header version %d\n",
2969 swap_header
->info
.version
);
2974 p
->cluster_next
= 1;
2977 maxpages
= max_swapfile_size();
2978 last_page
= swap_header
->info
.last_page
;
2980 pr_warn("Empty swap-file\n");
2983 if (last_page
> maxpages
) {
2984 pr_warn("Truncating oversized swap area, only using %luk out of %luk\n",
2985 maxpages
<< (PAGE_SHIFT
- 10),
2986 last_page
<< (PAGE_SHIFT
- 10));
2988 if (maxpages
> last_page
) {
2989 maxpages
= last_page
+ 1;
2990 /* p->max is an unsigned int: don't overflow it */
2991 if ((unsigned int)maxpages
== 0)
2992 maxpages
= UINT_MAX
;
2994 p
->highest_bit
= maxpages
- 1;
2998 swapfilepages
= i_size_read(inode
) >> PAGE_SHIFT
;
2999 if (swapfilepages
&& maxpages
> swapfilepages
) {
3000 pr_warn("Swap area shorter than signature indicates\n");
3003 if (swap_header
->info
.nr_badpages
&& S_ISREG(inode
->i_mode
))
3005 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
3011 #define SWAP_CLUSTER_INFO_COLS \
3012 DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
3013 #define SWAP_CLUSTER_SPACE_COLS \
3014 DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
3015 #define SWAP_CLUSTER_COLS \
3016 max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
3018 static int setup_swap_map_and_extents(struct swap_info_struct
*p
,
3019 union swap_header
*swap_header
,
3020 unsigned char *swap_map
,
3021 struct swap_cluster_info
*cluster_info
,
3022 unsigned long maxpages
,
3026 unsigned int nr_good_pages
;
3028 unsigned long nr_clusters
= DIV_ROUND_UP(maxpages
, SWAPFILE_CLUSTER
);
3029 unsigned long col
= p
->cluster_next
/ SWAPFILE_CLUSTER
% SWAP_CLUSTER_COLS
;
3030 unsigned long i
, idx
;
3032 nr_good_pages
= maxpages
- 1; /* omit header page */
3034 cluster_list_init(&p
->free_clusters
);
3035 cluster_list_init(&p
->discard_clusters
);
3037 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++) {
3038 unsigned int page_nr
= swap_header
->info
.badpages
[i
];
3039 if (page_nr
== 0 || page_nr
> swap_header
->info
.last_page
)
3041 if (page_nr
< maxpages
) {
3042 swap_map
[page_nr
] = SWAP_MAP_BAD
;
3045 * Haven't marked the cluster free yet, no list
3046 * operation involved
3048 inc_cluster_info_page(p
, cluster_info
, page_nr
);
3052 /* Haven't marked the cluster free yet, no list operation involved */
3053 for (i
= maxpages
; i
< round_up(maxpages
, SWAPFILE_CLUSTER
); i
++)
3054 inc_cluster_info_page(p
, cluster_info
, i
);
3056 if (nr_good_pages
) {
3057 swap_map
[0] = SWAP_MAP_BAD
;
3059 * Not mark the cluster free yet, no list
3060 * operation involved
3062 inc_cluster_info_page(p
, cluster_info
, 0);
3064 p
->pages
= nr_good_pages
;
3065 nr_extents
= setup_swap_extents(p
, span
);
3068 nr_good_pages
= p
->pages
;
3070 if (!nr_good_pages
) {
3071 pr_warn("Empty swap-file\n");
3080 * Reduce false cache line sharing between cluster_info and
3081 * sharing same address space.
3083 for (k
= 0; k
< SWAP_CLUSTER_COLS
; k
++) {
3084 j
= (k
+ col
) % SWAP_CLUSTER_COLS
;
3085 for (i
= 0; i
< DIV_ROUND_UP(nr_clusters
, SWAP_CLUSTER_COLS
); i
++) {
3086 idx
= i
* SWAP_CLUSTER_COLS
+ j
;
3087 if (idx
>= nr_clusters
)
3089 if (cluster_count(&cluster_info
[idx
]))
3091 cluster_set_flag(&cluster_info
[idx
], CLUSTER_FLAG_FREE
);
3092 cluster_list_add_tail(&p
->free_clusters
, cluster_info
,
3100 * Helper to sys_swapon determining if a given swap
3101 * backing device queue supports DISCARD operations.
3103 static bool swap_discardable(struct swap_info_struct
*si
)
3105 struct request_queue
*q
= bdev_get_queue(si
->bdev
);
3107 if (!q
|| !blk_queue_discard(q
))
3113 SYSCALL_DEFINE2(swapon
, const char __user
*, specialfile
, int, swap_flags
)
3115 struct swap_info_struct
*p
;
3116 struct filename
*name
;
3117 struct file
*swap_file
= NULL
;
3118 struct address_space
*mapping
;
3121 union swap_header
*swap_header
;
3124 unsigned long maxpages
;
3125 unsigned char *swap_map
= NULL
;
3126 struct swap_cluster_info
*cluster_info
= NULL
;
3127 unsigned long *frontswap_map
= NULL
;
3128 struct page
*page
= NULL
;
3129 struct inode
*inode
= NULL
;
3130 bool inced_nr_rotate_swap
= false;
3132 if (swap_flags
& ~SWAP_FLAGS_VALID
)
3135 if (!capable(CAP_SYS_ADMIN
))
3138 if (!swap_avail_heads
)
3141 p
= alloc_swap_info();
3145 INIT_WORK(&p
->discard_work
, swap_discard_work
);
3147 name
= getname(specialfile
);
3149 error
= PTR_ERR(name
);
3153 swap_file
= file_open_name(name
, O_RDWR
|O_LARGEFILE
, 0);
3154 if (IS_ERR(swap_file
)) {
3155 error
= PTR_ERR(swap_file
);
3160 p
->swap_file
= swap_file
;
3161 mapping
= swap_file
->f_mapping
;
3162 inode
= mapping
->host
;
3164 error
= claim_swapfile(p
, inode
);
3165 if (unlikely(error
))
3169 if (IS_SWAPFILE(inode
)) {
3171 goto bad_swap_unlock_inode
;
3175 * Read the swap header.
3177 if (!mapping
->a_ops
->readpage
) {
3179 goto bad_swap_unlock_inode
;
3181 page
= read_mapping_page(mapping
, 0, swap_file
);
3183 error
= PTR_ERR(page
);
3186 swap_header
= kmap(page
);
3188 maxpages
= read_swap_header(p
, swap_header
, inode
);
3189 if (unlikely(!maxpages
)) {
3191 goto bad_swap_unlock_inode
;
3194 /* OK, set up the swap map and apply the bad block list */
3195 swap_map
= vzalloc(maxpages
);
3198 goto bad_swap_unlock_inode
;
3201 if (bdi_cap_stable_pages_required(inode_to_bdi(inode
)))
3202 p
->flags
|= SWP_STABLE_WRITES
;
3204 if (bdi_cap_synchronous_io(inode_to_bdi(inode
)))
3205 p
->flags
|= SWP_SYNCHRONOUS_IO
;
3207 if (p
->bdev
&& blk_queue_nonrot(bdev_get_queue(p
->bdev
))) {
3209 unsigned long ci
, nr_cluster
;
3211 p
->flags
|= SWP_SOLIDSTATE
;
3213 * select a random position to start with to help wear leveling
3216 p
->cluster_next
= 1 + (prandom_u32() % p
->highest_bit
);
3217 nr_cluster
= DIV_ROUND_UP(maxpages
, SWAPFILE_CLUSTER
);
3219 cluster_info
= kvcalloc(nr_cluster
, sizeof(*cluster_info
),
3221 if (!cluster_info
) {
3223 goto bad_swap_unlock_inode
;
3226 for (ci
= 0; ci
< nr_cluster
; ci
++)
3227 spin_lock_init(&((cluster_info
+ ci
)->lock
));
3229 p
->percpu_cluster
= alloc_percpu(struct percpu_cluster
);
3230 if (!p
->percpu_cluster
) {
3232 goto bad_swap_unlock_inode
;
3234 for_each_possible_cpu(cpu
) {
3235 struct percpu_cluster
*cluster
;
3236 cluster
= per_cpu_ptr(p
->percpu_cluster
, cpu
);
3237 cluster_set_null(&cluster
->index
);
3240 atomic_inc(&nr_rotate_swap
);
3241 inced_nr_rotate_swap
= true;
3244 error
= swap_cgroup_swapon(p
->type
, maxpages
);
3246 goto bad_swap_unlock_inode
;
3248 nr_extents
= setup_swap_map_and_extents(p
, swap_header
, swap_map
,
3249 cluster_info
, maxpages
, &span
);
3250 if (unlikely(nr_extents
< 0)) {
3252 goto bad_swap_unlock_inode
;
3254 /* frontswap enabled? set up bit-per-page map for frontswap */
3255 if (IS_ENABLED(CONFIG_FRONTSWAP
))
3256 frontswap_map
= kvcalloc(BITS_TO_LONGS(maxpages
),
3260 if (p
->bdev
&&(swap_flags
& SWAP_FLAG_DISCARD
) && swap_discardable(p
)) {
3262 * When discard is enabled for swap with no particular
3263 * policy flagged, we set all swap discard flags here in
3264 * order to sustain backward compatibility with older
3265 * swapon(8) releases.
3267 p
->flags
|= (SWP_DISCARDABLE
| SWP_AREA_DISCARD
|
3271 * By flagging sys_swapon, a sysadmin can tell us to
3272 * either do single-time area discards only, or to just
3273 * perform discards for released swap page-clusters.
3274 * Now it's time to adjust the p->flags accordingly.
3276 if (swap_flags
& SWAP_FLAG_DISCARD_ONCE
)
3277 p
->flags
&= ~SWP_PAGE_DISCARD
;
3278 else if (swap_flags
& SWAP_FLAG_DISCARD_PAGES
)
3279 p
->flags
&= ~SWP_AREA_DISCARD
;
3281 /* issue a swapon-time discard if it's still required */
3282 if (p
->flags
& SWP_AREA_DISCARD
) {
3283 int err
= discard_swap(p
);
3285 pr_err("swapon: discard_swap(%p): %d\n",
3290 error
= init_swap_address_space(p
->type
, maxpages
);
3292 goto bad_swap_unlock_inode
;
3295 * Flush any pending IO and dirty mappings before we start using this
3298 inode
->i_flags
|= S_SWAPFILE
;
3299 error
= inode_drain_writes(inode
);
3301 inode
->i_flags
&= ~S_SWAPFILE
;
3302 goto free_swap_address_space
;
3305 mutex_lock(&swapon_mutex
);
3307 if (swap_flags
& SWAP_FLAG_PREFER
)
3309 (swap_flags
& SWAP_FLAG_PRIO_MASK
) >> SWAP_FLAG_PRIO_SHIFT
;
3310 enable_swap_info(p
, prio
, swap_map
, cluster_info
, frontswap_map
);
3312 pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
3313 p
->pages
<<(PAGE_SHIFT
-10), name
->name
, p
->prio
,
3314 nr_extents
, (unsigned long long)span
<<(PAGE_SHIFT
-10),
3315 (p
->flags
& SWP_SOLIDSTATE
) ? "SS" : "",
3316 (p
->flags
& SWP_DISCARDABLE
) ? "D" : "",
3317 (p
->flags
& SWP_AREA_DISCARD
) ? "s" : "",
3318 (p
->flags
& SWP_PAGE_DISCARD
) ? "c" : "",
3319 (frontswap_map
) ? "FS" : "");
3321 mutex_unlock(&swapon_mutex
);
3322 atomic_inc(&proc_poll_event
);
3323 wake_up_interruptible(&proc_poll_wait
);
3327 free_swap_address_space
:
3328 exit_swap_address_space(p
->type
);
3329 bad_swap_unlock_inode
:
3330 inode_unlock(inode
);
3332 free_percpu(p
->percpu_cluster
);
3333 p
->percpu_cluster
= NULL
;
3334 if (inode
&& S_ISBLK(inode
->i_mode
) && p
->bdev
) {
3335 set_blocksize(p
->bdev
, p
->old_block_size
);
3336 blkdev_put(p
->bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
3339 destroy_swap_extents(p
);
3340 swap_cgroup_swapoff(p
->type
);
3341 spin_lock(&swap_lock
);
3342 p
->swap_file
= NULL
;
3344 spin_unlock(&swap_lock
);
3346 kvfree(cluster_info
);
3347 kvfree(frontswap_map
);
3348 if (inced_nr_rotate_swap
)
3349 atomic_dec(&nr_rotate_swap
);
3351 filp_close(swap_file
, NULL
);
3353 if (page
&& !IS_ERR(page
)) {
3360 inode_unlock(inode
);
3362 enable_swap_slots_cache();
3366 void si_swapinfo(struct sysinfo
*val
)
3369 unsigned long nr_to_be_unused
= 0;
3371 spin_lock(&swap_lock
);
3372 for (type
= 0; type
< nr_swapfiles
; type
++) {
3373 struct swap_info_struct
*si
= swap_info
[type
];
3375 if ((si
->flags
& SWP_USED
) && !(si
->flags
& SWP_WRITEOK
))
3376 nr_to_be_unused
+= si
->inuse_pages
;
3378 val
->freeswap
= atomic_long_read(&nr_swap_pages
) + nr_to_be_unused
;
3379 val
->totalswap
= total_swap_pages
+ nr_to_be_unused
;
3380 spin_unlock(&swap_lock
);
3384 * Verify that a swap entry is valid and increment its swap map count.
3386 * Returns error code in following case.
3388 * - swp_entry is invalid -> EINVAL
3389 * - swp_entry is migration entry -> EINVAL
3390 * - swap-cache reference is requested but there is already one. -> EEXIST
3391 * - swap-cache reference is requested but the entry is not used. -> ENOENT
3392 * - swap-mapped reference requested but needs continued swap count. -> ENOMEM
3394 static int __swap_duplicate(swp_entry_t entry
, unsigned char usage
)
3396 struct swap_info_struct
*p
;
3397 struct swap_cluster_info
*ci
;
3398 unsigned long offset
;
3399 unsigned char count
;
3400 unsigned char has_cache
;
3403 p
= get_swap_device(entry
);
3407 offset
= swp_offset(entry
);
3408 ci
= lock_cluster_or_swap_info(p
, offset
);
3410 count
= p
->swap_map
[offset
];
3413 * swapin_readahead() doesn't check if a swap entry is valid, so the
3414 * swap entry could be SWAP_MAP_BAD. Check here with lock held.
3416 if (unlikely(swap_count(count
) == SWAP_MAP_BAD
)) {
3421 has_cache
= count
& SWAP_HAS_CACHE
;
3422 count
&= ~SWAP_HAS_CACHE
;
3425 if (usage
== SWAP_HAS_CACHE
) {
3427 /* set SWAP_HAS_CACHE if there is no cache and entry is used */
3428 if (!has_cache
&& count
)
3429 has_cache
= SWAP_HAS_CACHE
;
3430 else if (has_cache
) /* someone else added cache */
3432 else /* no users remaining */
3435 } else if (count
|| has_cache
) {
3437 if ((count
& ~COUNT_CONTINUED
) < SWAP_MAP_MAX
)
3439 else if ((count
& ~COUNT_CONTINUED
) > SWAP_MAP_MAX
)
3441 else if (swap_count_continued(p
, offset
, count
))
3442 count
= COUNT_CONTINUED
;
3446 err
= -ENOENT
; /* unused swap entry */
3448 p
->swap_map
[offset
] = count
| has_cache
;
3451 unlock_cluster_or_swap_info(p
, ci
);
3459 * Help swapoff by noting that swap entry belongs to shmem/tmpfs
3460 * (in which case its reference count is never incremented).
3462 void swap_shmem_alloc(swp_entry_t entry
)
3464 __swap_duplicate(entry
, SWAP_MAP_SHMEM
);
3468 * Increase reference count of swap entry by 1.
3469 * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
3470 * but could not be atomically allocated. Returns 0, just as if it succeeded,
3471 * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
3472 * might occur if a page table entry has got corrupted.
3474 int swap_duplicate(swp_entry_t entry
)
3478 while (!err
&& __swap_duplicate(entry
, 1) == -ENOMEM
)
3479 err
= add_swap_count_continuation(entry
, GFP_ATOMIC
);
3484 * @entry: swap entry for which we allocate swap cache.
3486 * Called when allocating swap cache for existing swap entry,
3487 * This can return error codes. Returns 0 at success.
3488 * -EBUSY means there is a swap cache.
3489 * Note: return code is different from swap_duplicate().
3491 int swapcache_prepare(swp_entry_t entry
)
3493 return __swap_duplicate(entry
, SWAP_HAS_CACHE
);
3496 struct swap_info_struct
*swp_swap_info(swp_entry_t entry
)
3498 return swap_type_to_swap_info(swp_type(entry
));
3501 struct swap_info_struct
*page_swap_info(struct page
*page
)
3503 swp_entry_t entry
= { .val
= page_private(page
) };
3504 return swp_swap_info(entry
);
3508 * out-of-line __page_file_ methods to avoid include hell.
3510 struct address_space
*__page_file_mapping(struct page
*page
)
3512 return page_swap_info(page
)->swap_file
->f_mapping
;
3514 EXPORT_SYMBOL_GPL(__page_file_mapping
);
3516 pgoff_t
__page_file_index(struct page
*page
)
3518 swp_entry_t swap
= { .val
= page_private(page
) };
3519 return swp_offset(swap
);
3521 EXPORT_SYMBOL_GPL(__page_file_index
);
3524 * add_swap_count_continuation - called when a swap count is duplicated
3525 * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
3526 * page of the original vmalloc'ed swap_map, to hold the continuation count
3527 * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called
3528 * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
3530 * These continuation pages are seldom referenced: the common paths all work
3531 * on the original swap_map, only referring to a continuation page when the
3532 * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
3534 * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
3535 * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
3536 * can be called after dropping locks.
3538 int add_swap_count_continuation(swp_entry_t entry
, gfp_t gfp_mask
)
3540 struct swap_info_struct
*si
;
3541 struct swap_cluster_info
*ci
;
3544 struct page
*list_page
;
3546 unsigned char count
;
3550 * When debugging, it's easier to use __GFP_ZERO here; but it's better
3551 * for latency not to zero a page while GFP_ATOMIC and holding locks.
3553 page
= alloc_page(gfp_mask
| __GFP_HIGHMEM
);
3555 si
= get_swap_device(entry
);
3558 * An acceptable race has occurred since the failing
3559 * __swap_duplicate(): the swap device may be swapoff
3563 spin_lock(&si
->lock
);
3565 offset
= swp_offset(entry
);
3567 ci
= lock_cluster(si
, offset
);
3569 count
= si
->swap_map
[offset
] & ~SWAP_HAS_CACHE
;
3571 if ((count
& ~COUNT_CONTINUED
) != SWAP_MAP_MAX
) {
3573 * The higher the swap count, the more likely it is that tasks
3574 * will race to add swap count continuation: we need to avoid
3575 * over-provisioning.
3586 * We are fortunate that although vmalloc_to_page uses pte_offset_map,
3587 * no architecture is using highmem pages for kernel page tables: so it
3588 * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps.
3590 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3591 offset
&= ~PAGE_MASK
;
3593 spin_lock(&si
->cont_lock
);
3595 * Page allocation does not initialize the page's lru field,
3596 * but it does always reset its private field.
3598 if (!page_private(head
)) {
3599 BUG_ON(count
& COUNT_CONTINUED
);
3600 INIT_LIST_HEAD(&head
->lru
);
3601 set_page_private(head
, SWP_CONTINUED
);
3602 si
->flags
|= SWP_CONTINUED
;
3605 list_for_each_entry(list_page
, &head
->lru
, lru
) {
3609 * If the previous map said no continuation, but we've found
3610 * a continuation page, free our allocation and use this one.
3612 if (!(count
& COUNT_CONTINUED
))
3613 goto out_unlock_cont
;
3615 map
= kmap_atomic(list_page
) + offset
;
3620 * If this continuation count now has some space in it,
3621 * free our allocation and use this one.
3623 if ((count
& ~COUNT_CONTINUED
) != SWAP_CONT_MAX
)
3624 goto out_unlock_cont
;
3627 list_add_tail(&page
->lru
, &head
->lru
);
3628 page
= NULL
; /* now it's attached, don't free it */
3630 spin_unlock(&si
->cont_lock
);
3633 spin_unlock(&si
->lock
);
3634 put_swap_device(si
);
3642 * swap_count_continued - when the original swap_map count is incremented
3643 * from SWAP_MAP_MAX, check if there is already a continuation page to carry
3644 * into, carry if so, or else fail until a new continuation page is allocated;
3645 * when the original swap_map count is decremented from 0 with continuation,
3646 * borrow from the continuation and report whether it still holds more.
3647 * Called while __swap_duplicate() or swap_entry_free() holds swap or cluster
3650 static bool swap_count_continued(struct swap_info_struct
*si
,
3651 pgoff_t offset
, unsigned char count
)
3658 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3659 if (page_private(head
) != SWP_CONTINUED
) {
3660 BUG_ON(count
& COUNT_CONTINUED
);
3661 return false; /* need to add count continuation */
3664 spin_lock(&si
->cont_lock
);
3665 offset
&= ~PAGE_MASK
;
3666 page
= list_entry(head
->lru
.next
, struct page
, lru
);
3667 map
= kmap_atomic(page
) + offset
;
3669 if (count
== SWAP_MAP_MAX
) /* initial increment from swap_map */
3670 goto init_map
; /* jump over SWAP_CONT_MAX checks */
3672 if (count
== (SWAP_MAP_MAX
| COUNT_CONTINUED
)) { /* incrementing */
3674 * Think of how you add 1 to 999
3676 while (*map
== (SWAP_CONT_MAX
| COUNT_CONTINUED
)) {
3678 page
= list_entry(page
->lru
.next
, struct page
, lru
);
3679 BUG_ON(page
== head
);
3680 map
= kmap_atomic(page
) + offset
;
3682 if (*map
== SWAP_CONT_MAX
) {
3684 page
= list_entry(page
->lru
.next
, struct page
, lru
);
3686 ret
= false; /* add count continuation */
3689 map
= kmap_atomic(page
) + offset
;
3690 init_map
: *map
= 0; /* we didn't zero the page */
3694 page
= list_entry(page
->lru
.prev
, struct page
, lru
);
3695 while (page
!= head
) {
3696 map
= kmap_atomic(page
) + offset
;
3697 *map
= COUNT_CONTINUED
;
3699 page
= list_entry(page
->lru
.prev
, struct page
, lru
);
3701 ret
= true; /* incremented */
3703 } else { /* decrementing */
3705 * Think of how you subtract 1 from 1000
3707 BUG_ON(count
!= COUNT_CONTINUED
);
3708 while (*map
== COUNT_CONTINUED
) {
3710 page
= list_entry(page
->lru
.next
, struct page
, lru
);
3711 BUG_ON(page
== head
);
3712 map
= kmap_atomic(page
) + offset
;
3719 page
= list_entry(page
->lru
.prev
, struct page
, lru
);
3720 while (page
!= head
) {
3721 map
= kmap_atomic(page
) + offset
;
3722 *map
= SWAP_CONT_MAX
| count
;
3723 count
= COUNT_CONTINUED
;
3725 page
= list_entry(page
->lru
.prev
, struct page
, lru
);
3727 ret
= count
== COUNT_CONTINUED
;
3730 spin_unlock(&si
->cont_lock
);
3735 * free_swap_count_continuations - swapoff free all the continuation pages
3736 * appended to the swap_map, after swap_map is quiesced, before vfree'ing it.
3738 static void free_swap_count_continuations(struct swap_info_struct
*si
)
3742 for (offset
= 0; offset
< si
->max
; offset
+= PAGE_SIZE
) {
3744 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3745 if (page_private(head
)) {
3746 struct page
*page
, *next
;
3748 list_for_each_entry_safe(page
, next
, &head
->lru
, lru
) {
3749 list_del(&page
->lru
);
3756 #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
3757 void mem_cgroup_throttle_swaprate(struct mem_cgroup
*memcg
, int node
,
3760 struct swap_info_struct
*si
, *next
;
3761 if (!(gfp_mask
& __GFP_IO
) || !memcg
)
3764 if (!blk_cgroup_congested())
3768 * We've already scheduled a throttle, avoid taking the global swap
3771 if (current
->throttle_queue
)
3774 spin_lock(&swap_avail_lock
);
3775 plist_for_each_entry_safe(si
, next
, &swap_avail_heads
[node
],
3776 avail_lists
[node
]) {
3778 blkcg_schedule_throttle(bdev_get_queue(si
->bdev
),
3783 spin_unlock(&swap_avail_lock
);
3787 static int __init
swapfile_init(void)
3791 swap_avail_heads
= kmalloc_array(nr_node_ids
, sizeof(struct plist_head
),
3793 if (!swap_avail_heads
) {
3794 pr_emerg("Not enough memory for swap heads, swap is disabled\n");
3799 plist_head_init(&swap_avail_heads
[nid
]);
3803 subsys_initcall(swapfile_init
);