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/tlbflush.h>
44 #include <linux/swapops.h>
45 #include <linux/swap_cgroup.h>
47 static bool swap_count_continued(struct swap_info_struct
*, pgoff_t
,
49 static void free_swap_count_continuations(struct swap_info_struct
*);
50 static sector_t
map_swap_entry(swp_entry_t
, struct block_device
**);
52 DEFINE_SPINLOCK(swap_lock
);
53 static unsigned int nr_swapfiles
;
54 atomic_long_t nr_swap_pages
;
56 * Some modules use swappable objects and may try to swap them out under
57 * memory pressure (via the shrinker). Before doing so, they may wish to
58 * check to see if any swap space is available.
60 EXPORT_SYMBOL_GPL(nr_swap_pages
);
61 /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */
62 long total_swap_pages
;
63 static int least_priority
= -1;
65 static const char Bad_file
[] = "Bad swap file entry ";
66 static const char Unused_file
[] = "Unused swap file entry ";
67 static const char Bad_offset
[] = "Bad swap offset entry ";
68 static const char Unused_offset
[] = "Unused swap offset entry ";
71 * all active swap_info_structs
72 * protected with swap_lock, and ordered by priority.
74 PLIST_HEAD(swap_active_head
);
77 * all available (active, not full) swap_info_structs
78 * protected with swap_avail_lock, ordered by priority.
79 * This is used by get_swap_page() instead of swap_active_head
80 * because swap_active_head includes all swap_info_structs,
81 * but get_swap_page() doesn't need to look at full ones.
82 * This uses its own lock instead of swap_lock because when a
83 * swap_info_struct changes between not-full/full, it needs to
84 * add/remove itself to/from this list, but the swap_info_struct->lock
85 * is held and the locking order requires swap_lock to be taken
86 * before any swap_info_struct->lock.
88 static struct plist_head
*swap_avail_heads
;
89 static DEFINE_SPINLOCK(swap_avail_lock
);
91 struct swap_info_struct
*swap_info
[MAX_SWAPFILES
];
93 static DEFINE_MUTEX(swapon_mutex
);
95 static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait
);
96 /* Activity counter to indicate that a swapon or swapoff has occurred */
97 static atomic_t proc_poll_event
= ATOMIC_INIT(0);
99 atomic_t nr_rotate_swap
= ATOMIC_INIT(0);
101 static struct swap_info_struct
*swap_type_to_swap_info(int type
)
103 if (type
>= READ_ONCE(nr_swapfiles
))
106 smp_rmb(); /* Pairs with smp_wmb in alloc_swap_info. */
107 return READ_ONCE(swap_info
[type
]);
110 static inline unsigned char swap_count(unsigned char ent
)
112 return ent
& ~SWAP_HAS_CACHE
; /* may include COUNT_CONTINUED flag */
115 /* Reclaim the swap entry anyway if possible */
116 #define TTRS_ANYWAY 0x1
118 * Reclaim the swap entry if there are no more mappings of the
121 #define TTRS_UNMAPPED 0x2
122 /* Reclaim the swap entry if swap is getting full*/
123 #define TTRS_FULL 0x4
125 /* returns 1 if swap entry is freed */
126 static int __try_to_reclaim_swap(struct swap_info_struct
*si
,
127 unsigned long offset
, unsigned long flags
)
129 swp_entry_t entry
= swp_entry(si
->type
, offset
);
133 page
= find_get_page(swap_address_space(entry
), offset
);
137 * When this function is called from scan_swap_map_slots() and it's
138 * called by vmscan.c at reclaiming pages. So, we hold a lock on a page,
139 * here. We have to use trylock for avoiding deadlock. This is a special
140 * case and you should use try_to_free_swap() with explicit lock_page()
141 * in usual operations.
143 if (trylock_page(page
)) {
144 if ((flags
& TTRS_ANYWAY
) ||
145 ((flags
& TTRS_UNMAPPED
) && !page_mapped(page
)) ||
146 ((flags
& TTRS_FULL
) && mem_cgroup_swap_full(page
)))
147 ret
= try_to_free_swap(page
);
154 static inline struct swap_extent
*first_se(struct swap_info_struct
*sis
)
156 struct rb_node
*rb
= rb_first(&sis
->swap_extent_root
);
157 return rb_entry(rb
, struct swap_extent
, rb_node
);
160 static inline struct swap_extent
*next_se(struct swap_extent
*se
)
162 struct rb_node
*rb
= rb_next(&se
->rb_node
);
163 return rb
? rb_entry(rb
, struct swap_extent
, rb_node
) : NULL
;
167 * swapon tell device that all the old swap contents can be discarded,
168 * to allow the swap device to optimize its wear-levelling.
170 static int discard_swap(struct swap_info_struct
*si
)
172 struct swap_extent
*se
;
173 sector_t start_block
;
177 /* Do not discard the swap header page! */
179 start_block
= (se
->start_block
+ 1) << (PAGE_SHIFT
- 9);
180 nr_blocks
= ((sector_t
)se
->nr_pages
- 1) << (PAGE_SHIFT
- 9);
182 err
= blkdev_issue_discard(si
->bdev
, start_block
,
183 nr_blocks
, GFP_KERNEL
, 0);
189 for (se
= next_se(se
); se
; se
= next_se(se
)) {
190 start_block
= se
->start_block
<< (PAGE_SHIFT
- 9);
191 nr_blocks
= (sector_t
)se
->nr_pages
<< (PAGE_SHIFT
- 9);
193 err
= blkdev_issue_discard(si
->bdev
, start_block
,
194 nr_blocks
, GFP_KERNEL
, 0);
200 return err
; /* That will often be -EOPNOTSUPP */
203 static struct swap_extent
*
204 offset_to_swap_extent(struct swap_info_struct
*sis
, unsigned long offset
)
206 struct swap_extent
*se
;
209 rb
= sis
->swap_extent_root
.rb_node
;
211 se
= rb_entry(rb
, struct swap_extent
, rb_node
);
212 if (offset
< se
->start_page
)
214 else if (offset
>= se
->start_page
+ se
->nr_pages
)
219 /* It *must* be present */
224 * swap allocation tell device that a cluster of swap can now be discarded,
225 * to allow the swap device to optimize its wear-levelling.
227 static void discard_swap_cluster(struct swap_info_struct
*si
,
228 pgoff_t start_page
, pgoff_t nr_pages
)
230 struct swap_extent
*se
= offset_to_swap_extent(si
, start_page
);
233 pgoff_t offset
= start_page
- se
->start_page
;
234 sector_t start_block
= se
->start_block
+ offset
;
235 sector_t nr_blocks
= se
->nr_pages
- offset
;
237 if (nr_blocks
> nr_pages
)
238 nr_blocks
= nr_pages
;
239 start_page
+= nr_blocks
;
240 nr_pages
-= nr_blocks
;
242 start_block
<<= PAGE_SHIFT
- 9;
243 nr_blocks
<<= PAGE_SHIFT
- 9;
244 if (blkdev_issue_discard(si
->bdev
, start_block
,
245 nr_blocks
, GFP_NOIO
, 0))
252 #ifdef CONFIG_THP_SWAP
253 #define SWAPFILE_CLUSTER HPAGE_PMD_NR
255 #define swap_entry_size(size) (size)
257 #define SWAPFILE_CLUSTER 256
260 * Define swap_entry_size() as constant to let compiler to optimize
261 * out some code if !CONFIG_THP_SWAP
263 #define swap_entry_size(size) 1
265 #define LATENCY_LIMIT 256
267 static inline void cluster_set_flag(struct swap_cluster_info
*info
,
273 static inline unsigned int cluster_count(struct swap_cluster_info
*info
)
278 static inline void cluster_set_count(struct swap_cluster_info
*info
,
284 static inline void cluster_set_count_flag(struct swap_cluster_info
*info
,
285 unsigned int c
, unsigned int f
)
291 static inline unsigned int cluster_next(struct swap_cluster_info
*info
)
296 static inline void cluster_set_next(struct swap_cluster_info
*info
,
302 static inline void cluster_set_next_flag(struct swap_cluster_info
*info
,
303 unsigned int n
, unsigned int f
)
309 static inline bool cluster_is_free(struct swap_cluster_info
*info
)
311 return info
->flags
& CLUSTER_FLAG_FREE
;
314 static inline bool cluster_is_null(struct swap_cluster_info
*info
)
316 return info
->flags
& CLUSTER_FLAG_NEXT_NULL
;
319 static inline void cluster_set_null(struct swap_cluster_info
*info
)
321 info
->flags
= CLUSTER_FLAG_NEXT_NULL
;
325 static inline bool cluster_is_huge(struct swap_cluster_info
*info
)
327 if (IS_ENABLED(CONFIG_THP_SWAP
))
328 return info
->flags
& CLUSTER_FLAG_HUGE
;
332 static inline void cluster_clear_huge(struct swap_cluster_info
*info
)
334 info
->flags
&= ~CLUSTER_FLAG_HUGE
;
337 static inline struct swap_cluster_info
*lock_cluster(struct swap_info_struct
*si
,
338 unsigned long offset
)
340 struct swap_cluster_info
*ci
;
342 ci
= si
->cluster_info
;
344 ci
+= offset
/ SWAPFILE_CLUSTER
;
345 spin_lock(&ci
->lock
);
350 static inline void unlock_cluster(struct swap_cluster_info
*ci
)
353 spin_unlock(&ci
->lock
);
357 * Determine the locking method in use for this device. Return
358 * swap_cluster_info if SSD-style cluster-based locking is in place.
360 static inline struct swap_cluster_info
*lock_cluster_or_swap_info(
361 struct swap_info_struct
*si
, unsigned long offset
)
363 struct swap_cluster_info
*ci
;
365 /* Try to use fine-grained SSD-style locking if available: */
366 ci
= lock_cluster(si
, offset
);
367 /* Otherwise, fall back to traditional, coarse locking: */
369 spin_lock(&si
->lock
);
374 static inline void unlock_cluster_or_swap_info(struct swap_info_struct
*si
,
375 struct swap_cluster_info
*ci
)
380 spin_unlock(&si
->lock
);
383 static inline bool cluster_list_empty(struct swap_cluster_list
*list
)
385 return cluster_is_null(&list
->head
);
388 static inline unsigned int cluster_list_first(struct swap_cluster_list
*list
)
390 return cluster_next(&list
->head
);
393 static void cluster_list_init(struct swap_cluster_list
*list
)
395 cluster_set_null(&list
->head
);
396 cluster_set_null(&list
->tail
);
399 static void cluster_list_add_tail(struct swap_cluster_list
*list
,
400 struct swap_cluster_info
*ci
,
403 if (cluster_list_empty(list
)) {
404 cluster_set_next_flag(&list
->head
, idx
, 0);
405 cluster_set_next_flag(&list
->tail
, idx
, 0);
407 struct swap_cluster_info
*ci_tail
;
408 unsigned int tail
= cluster_next(&list
->tail
);
411 * Nested cluster lock, but both cluster locks are
412 * only acquired when we held swap_info_struct->lock
415 spin_lock_nested(&ci_tail
->lock
, SINGLE_DEPTH_NESTING
);
416 cluster_set_next(ci_tail
, idx
);
417 spin_unlock(&ci_tail
->lock
);
418 cluster_set_next_flag(&list
->tail
, idx
, 0);
422 static unsigned int cluster_list_del_first(struct swap_cluster_list
*list
,
423 struct swap_cluster_info
*ci
)
427 idx
= cluster_next(&list
->head
);
428 if (cluster_next(&list
->tail
) == idx
) {
429 cluster_set_null(&list
->head
);
430 cluster_set_null(&list
->tail
);
432 cluster_set_next_flag(&list
->head
,
433 cluster_next(&ci
[idx
]), 0);
438 /* Add a cluster to discard list and schedule it to do discard */
439 static void swap_cluster_schedule_discard(struct swap_info_struct
*si
,
443 * If scan_swap_map() can't find a free cluster, it will check
444 * si->swap_map directly. To make sure the discarding cluster isn't
445 * taken by scan_swap_map(), mark the swap entries bad (occupied). It
446 * will be cleared after discard
448 memset(si
->swap_map
+ idx
* SWAPFILE_CLUSTER
,
449 SWAP_MAP_BAD
, SWAPFILE_CLUSTER
);
451 cluster_list_add_tail(&si
->discard_clusters
, si
->cluster_info
, idx
);
453 schedule_work(&si
->discard_work
);
456 static void __free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
458 struct swap_cluster_info
*ci
= si
->cluster_info
;
460 cluster_set_flag(ci
+ idx
, CLUSTER_FLAG_FREE
);
461 cluster_list_add_tail(&si
->free_clusters
, ci
, idx
);
465 * Doing discard actually. After a cluster discard is finished, the cluster
466 * will be added to free cluster list. caller should hold si->lock.
468 static void swap_do_scheduled_discard(struct swap_info_struct
*si
)
470 struct swap_cluster_info
*info
, *ci
;
473 info
= si
->cluster_info
;
475 while (!cluster_list_empty(&si
->discard_clusters
)) {
476 idx
= cluster_list_del_first(&si
->discard_clusters
, info
);
477 spin_unlock(&si
->lock
);
479 discard_swap_cluster(si
, idx
* SWAPFILE_CLUSTER
,
482 spin_lock(&si
->lock
);
483 ci
= lock_cluster(si
, idx
* SWAPFILE_CLUSTER
);
484 __free_cluster(si
, idx
);
485 memset(si
->swap_map
+ idx
* SWAPFILE_CLUSTER
,
486 0, SWAPFILE_CLUSTER
);
491 static void swap_discard_work(struct work_struct
*work
)
493 struct swap_info_struct
*si
;
495 si
= container_of(work
, struct swap_info_struct
, discard_work
);
497 spin_lock(&si
->lock
);
498 swap_do_scheduled_discard(si
);
499 spin_unlock(&si
->lock
);
502 static void alloc_cluster(struct swap_info_struct
*si
, unsigned long idx
)
504 struct swap_cluster_info
*ci
= si
->cluster_info
;
506 VM_BUG_ON(cluster_list_first(&si
->free_clusters
) != idx
);
507 cluster_list_del_first(&si
->free_clusters
, ci
);
508 cluster_set_count_flag(ci
+ idx
, 0, 0);
511 static void free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
513 struct swap_cluster_info
*ci
= si
->cluster_info
+ idx
;
515 VM_BUG_ON(cluster_count(ci
) != 0);
517 * If the swap is discardable, prepare discard the cluster
518 * instead of free it immediately. The cluster will be freed
521 if ((si
->flags
& (SWP_WRITEOK
| SWP_PAGE_DISCARD
)) ==
522 (SWP_WRITEOK
| SWP_PAGE_DISCARD
)) {
523 swap_cluster_schedule_discard(si
, idx
);
527 __free_cluster(si
, idx
);
531 * The cluster corresponding to page_nr will be used. The cluster will be
532 * removed from free cluster list and its usage counter will be increased.
534 static void inc_cluster_info_page(struct swap_info_struct
*p
,
535 struct swap_cluster_info
*cluster_info
, unsigned long page_nr
)
537 unsigned long idx
= page_nr
/ SWAPFILE_CLUSTER
;
541 if (cluster_is_free(&cluster_info
[idx
]))
542 alloc_cluster(p
, idx
);
544 VM_BUG_ON(cluster_count(&cluster_info
[idx
]) >= SWAPFILE_CLUSTER
);
545 cluster_set_count(&cluster_info
[idx
],
546 cluster_count(&cluster_info
[idx
]) + 1);
550 * The cluster corresponding to page_nr decreases one usage. If the usage
551 * counter becomes 0, which means no page in the cluster is in using, we can
552 * optionally discard the cluster and add it to free cluster list.
554 static void dec_cluster_info_page(struct swap_info_struct
*p
,
555 struct swap_cluster_info
*cluster_info
, unsigned long page_nr
)
557 unsigned long idx
= page_nr
/ SWAPFILE_CLUSTER
;
562 VM_BUG_ON(cluster_count(&cluster_info
[idx
]) == 0);
563 cluster_set_count(&cluster_info
[idx
],
564 cluster_count(&cluster_info
[idx
]) - 1);
566 if (cluster_count(&cluster_info
[idx
]) == 0)
567 free_cluster(p
, idx
);
571 * It's possible scan_swap_map() uses a free cluster in the middle of free
572 * cluster list. Avoiding such abuse to avoid list corruption.
575 scan_swap_map_ssd_cluster_conflict(struct swap_info_struct
*si
,
576 unsigned long offset
)
578 struct percpu_cluster
*percpu_cluster
;
581 offset
/= SWAPFILE_CLUSTER
;
582 conflict
= !cluster_list_empty(&si
->free_clusters
) &&
583 offset
!= cluster_list_first(&si
->free_clusters
) &&
584 cluster_is_free(&si
->cluster_info
[offset
]);
589 percpu_cluster
= this_cpu_ptr(si
->percpu_cluster
);
590 cluster_set_null(&percpu_cluster
->index
);
595 * Try to get a swap entry from current cpu's swap entry pool (a cluster). This
596 * might involve allocating a new cluster for current CPU too.
598 static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct
*si
,
599 unsigned long *offset
, unsigned long *scan_base
)
601 struct percpu_cluster
*cluster
;
602 struct swap_cluster_info
*ci
;
603 unsigned long tmp
, max
;
606 cluster
= this_cpu_ptr(si
->percpu_cluster
);
607 if (cluster_is_null(&cluster
->index
)) {
608 if (!cluster_list_empty(&si
->free_clusters
)) {
609 cluster
->index
= si
->free_clusters
.head
;
610 cluster
->next
= cluster_next(&cluster
->index
) *
612 } else if (!cluster_list_empty(&si
->discard_clusters
)) {
614 * we don't have free cluster but have some clusters in
615 * discarding, do discard now and reclaim them, then
616 * reread cluster_next_cpu since we dropped si->lock
618 swap_do_scheduled_discard(si
);
619 *scan_base
= this_cpu_read(*si
->cluster_next_cpu
);
620 *offset
= *scan_base
;
627 * Other CPUs can use our cluster if they can't find a free cluster,
628 * check if there is still free entry in the cluster
631 max
= min_t(unsigned long, si
->max
,
632 (cluster_next(&cluster
->index
) + 1) * SWAPFILE_CLUSTER
);
634 ci
= lock_cluster(si
, tmp
);
636 if (!si
->swap_map
[tmp
])
643 cluster_set_null(&cluster
->index
);
646 cluster
->next
= tmp
+ 1;
652 static void __del_from_avail_list(struct swap_info_struct
*p
)
657 plist_del(&p
->avail_lists
[nid
], &swap_avail_heads
[nid
]);
660 static void del_from_avail_list(struct swap_info_struct
*p
)
662 spin_lock(&swap_avail_lock
);
663 __del_from_avail_list(p
);
664 spin_unlock(&swap_avail_lock
);
667 static void swap_range_alloc(struct swap_info_struct
*si
, unsigned long offset
,
668 unsigned int nr_entries
)
670 unsigned int end
= offset
+ nr_entries
- 1;
672 if (offset
== si
->lowest_bit
)
673 si
->lowest_bit
+= nr_entries
;
674 if (end
== si
->highest_bit
)
675 si
->highest_bit
-= nr_entries
;
676 si
->inuse_pages
+= nr_entries
;
677 if (si
->inuse_pages
== si
->pages
) {
678 si
->lowest_bit
= si
->max
;
680 del_from_avail_list(si
);
684 static void add_to_avail_list(struct swap_info_struct
*p
)
688 spin_lock(&swap_avail_lock
);
690 WARN_ON(!plist_node_empty(&p
->avail_lists
[nid
]));
691 plist_add(&p
->avail_lists
[nid
], &swap_avail_heads
[nid
]);
693 spin_unlock(&swap_avail_lock
);
696 static void swap_range_free(struct swap_info_struct
*si
, unsigned long offset
,
697 unsigned int nr_entries
)
699 unsigned long begin
= offset
;
700 unsigned long end
= offset
+ nr_entries
- 1;
701 void (*swap_slot_free_notify
)(struct block_device
*, unsigned long);
703 if (offset
< si
->lowest_bit
)
704 si
->lowest_bit
= offset
;
705 if (end
> si
->highest_bit
) {
706 bool was_full
= !si
->highest_bit
;
708 si
->highest_bit
= end
;
709 if (was_full
&& (si
->flags
& SWP_WRITEOK
))
710 add_to_avail_list(si
);
712 atomic_long_add(nr_entries
, &nr_swap_pages
);
713 si
->inuse_pages
-= nr_entries
;
714 if (si
->flags
& SWP_BLKDEV
)
715 swap_slot_free_notify
=
716 si
->bdev
->bd_disk
->fops
->swap_slot_free_notify
;
718 swap_slot_free_notify
= NULL
;
719 while (offset
<= end
) {
720 frontswap_invalidate_page(si
->type
, offset
);
721 if (swap_slot_free_notify
)
722 swap_slot_free_notify(si
->bdev
, offset
);
725 clear_shadow_from_swap_cache(si
->type
, begin
, end
);
728 static void set_cluster_next(struct swap_info_struct
*si
, unsigned long next
)
732 if (!(si
->flags
& SWP_SOLIDSTATE
)) {
733 si
->cluster_next
= next
;
737 prev
= this_cpu_read(*si
->cluster_next_cpu
);
739 * Cross the swap address space size aligned trunk, choose
740 * another trunk randomly to avoid lock contention on swap
741 * address space if possible.
743 if ((prev
>> SWAP_ADDRESS_SPACE_SHIFT
) !=
744 (next
>> SWAP_ADDRESS_SPACE_SHIFT
)) {
745 /* No free swap slots available */
746 if (si
->highest_bit
<= si
->lowest_bit
)
748 next
= si
->lowest_bit
+
749 prandom_u32_max(si
->highest_bit
- si
->lowest_bit
+ 1);
750 next
= ALIGN_DOWN(next
, SWAP_ADDRESS_SPACE_PAGES
);
751 next
= max_t(unsigned int, next
, si
->lowest_bit
);
753 this_cpu_write(*si
->cluster_next_cpu
, next
);
756 static int scan_swap_map_slots(struct swap_info_struct
*si
,
757 unsigned char usage
, int nr
,
760 struct swap_cluster_info
*ci
;
761 unsigned long offset
;
762 unsigned long scan_base
;
763 unsigned long last_in_cluster
= 0;
764 int latency_ration
= LATENCY_LIMIT
;
766 bool scanned_many
= false;
769 * We try to cluster swap pages by allocating them sequentially
770 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
771 * way, however, we resort to first-free allocation, starting
772 * a new cluster. This prevents us from scattering swap pages
773 * all over the entire swap partition, so that we reduce
774 * overall disk seek times between swap pages. -- sct
775 * But we do now try to find an empty cluster. -Andrea
776 * And we let swap pages go all over an SSD partition. Hugh
779 si
->flags
+= SWP_SCANNING
;
781 * Use percpu scan base for SSD to reduce lock contention on
782 * cluster and swap cache. For HDD, sequential access is more
785 if (si
->flags
& SWP_SOLIDSTATE
)
786 scan_base
= this_cpu_read(*si
->cluster_next_cpu
);
788 scan_base
= si
->cluster_next
;
792 if (si
->cluster_info
) {
793 if (!scan_swap_map_try_ssd_cluster(si
, &offset
, &scan_base
))
795 } else if (unlikely(!si
->cluster_nr
--)) {
796 if (si
->pages
- si
->inuse_pages
< SWAPFILE_CLUSTER
) {
797 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
801 spin_unlock(&si
->lock
);
804 * If seek is expensive, start searching for new cluster from
805 * start of partition, to minimize the span of allocated swap.
806 * If seek is cheap, that is the SWP_SOLIDSTATE si->cluster_info
807 * case, just handled by scan_swap_map_try_ssd_cluster() above.
809 scan_base
= offset
= si
->lowest_bit
;
810 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
- 1;
812 /* Locate the first empty (unaligned) cluster */
813 for (; last_in_cluster
<= si
->highest_bit
; offset
++) {
814 if (si
->swap_map
[offset
])
815 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
;
816 else if (offset
== last_in_cluster
) {
817 spin_lock(&si
->lock
);
818 offset
-= SWAPFILE_CLUSTER
- 1;
819 si
->cluster_next
= offset
;
820 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
823 if (unlikely(--latency_ration
< 0)) {
825 latency_ration
= LATENCY_LIMIT
;
830 spin_lock(&si
->lock
);
831 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
835 if (si
->cluster_info
) {
836 while (scan_swap_map_ssd_cluster_conflict(si
, offset
)) {
837 /* take a break if we already got some slots */
840 if (!scan_swap_map_try_ssd_cluster(si
, &offset
,
845 if (!(si
->flags
& SWP_WRITEOK
))
847 if (!si
->highest_bit
)
849 if (offset
> si
->highest_bit
)
850 scan_base
= offset
= si
->lowest_bit
;
852 ci
= lock_cluster(si
, offset
);
853 /* reuse swap entry of cache-only swap if not busy. */
854 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
857 spin_unlock(&si
->lock
);
858 swap_was_freed
= __try_to_reclaim_swap(si
, offset
, TTRS_ANYWAY
);
859 spin_lock(&si
->lock
);
860 /* entry was freed successfully, try to use this again */
863 goto scan
; /* check next one */
866 if (si
->swap_map
[offset
]) {
873 si
->swap_map
[offset
] = usage
;
874 inc_cluster_info_page(si
, si
->cluster_info
, offset
);
877 swap_range_alloc(si
, offset
, 1);
878 slots
[n_ret
++] = swp_entry(si
->type
, offset
);
880 /* got enough slots or reach max slots? */
881 if ((n_ret
== nr
) || (offset
>= si
->highest_bit
))
884 /* search for next available slot */
886 /* time to take a break? */
887 if (unlikely(--latency_ration
< 0)) {
890 spin_unlock(&si
->lock
);
892 spin_lock(&si
->lock
);
893 latency_ration
= LATENCY_LIMIT
;
896 /* try to get more slots in cluster */
897 if (si
->cluster_info
) {
898 if (scan_swap_map_try_ssd_cluster(si
, &offset
, &scan_base
))
900 } else if (si
->cluster_nr
&& !si
->swap_map
[++offset
]) {
901 /* non-ssd case, still more slots in cluster? */
907 * Even if there's no free clusters available (fragmented),
908 * try to scan a little more quickly with lock held unless we
909 * have scanned too many slots already.
912 unsigned long scan_limit
;
914 if (offset
< scan_base
)
915 scan_limit
= scan_base
;
917 scan_limit
= si
->highest_bit
;
918 for (; offset
<= scan_limit
&& --latency_ration
> 0;
920 if (!si
->swap_map
[offset
])
926 set_cluster_next(si
, offset
+ 1);
927 si
->flags
-= SWP_SCANNING
;
931 spin_unlock(&si
->lock
);
932 while (++offset
<= si
->highest_bit
) {
933 if (!si
->swap_map
[offset
]) {
934 spin_lock(&si
->lock
);
937 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
938 spin_lock(&si
->lock
);
941 if (unlikely(--latency_ration
< 0)) {
943 latency_ration
= LATENCY_LIMIT
;
947 offset
= si
->lowest_bit
;
948 while (offset
< scan_base
) {
949 if (!si
->swap_map
[offset
]) {
950 spin_lock(&si
->lock
);
953 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
954 spin_lock(&si
->lock
);
957 if (unlikely(--latency_ration
< 0)) {
959 latency_ration
= LATENCY_LIMIT
;
964 spin_lock(&si
->lock
);
967 si
->flags
-= SWP_SCANNING
;
971 static int swap_alloc_cluster(struct swap_info_struct
*si
, swp_entry_t
*slot
)
974 struct swap_cluster_info
*ci
;
975 unsigned long offset
, i
;
979 * Should not even be attempting cluster allocations when huge
980 * page swap is disabled. Warn and fail the allocation.
982 if (!IS_ENABLED(CONFIG_THP_SWAP
)) {
987 if (cluster_list_empty(&si
->free_clusters
))
990 idx
= cluster_list_first(&si
->free_clusters
);
991 offset
= idx
* SWAPFILE_CLUSTER
;
992 ci
= lock_cluster(si
, offset
);
993 alloc_cluster(si
, idx
);
994 cluster_set_count_flag(ci
, SWAPFILE_CLUSTER
, CLUSTER_FLAG_HUGE
);
996 map
= si
->swap_map
+ offset
;
997 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++)
998 map
[i
] = SWAP_HAS_CACHE
;
1000 swap_range_alloc(si
, offset
, SWAPFILE_CLUSTER
);
1001 *slot
= swp_entry(si
->type
, offset
);
1006 static void swap_free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
1008 unsigned long offset
= idx
* SWAPFILE_CLUSTER
;
1009 struct swap_cluster_info
*ci
;
1011 ci
= lock_cluster(si
, offset
);
1012 memset(si
->swap_map
+ offset
, 0, SWAPFILE_CLUSTER
);
1013 cluster_set_count_flag(ci
, 0, 0);
1014 free_cluster(si
, idx
);
1016 swap_range_free(si
, offset
, SWAPFILE_CLUSTER
);
1019 static unsigned long scan_swap_map(struct swap_info_struct
*si
,
1020 unsigned char usage
)
1025 n_ret
= scan_swap_map_slots(si
, usage
, 1, &entry
);
1028 return swp_offset(entry
);
1034 int get_swap_pages(int n_goal
, swp_entry_t swp_entries
[], int entry_size
)
1036 unsigned long size
= swap_entry_size(entry_size
);
1037 struct swap_info_struct
*si
, *next
;
1042 /* Only single cluster request supported */
1043 WARN_ON_ONCE(n_goal
> 1 && size
== SWAPFILE_CLUSTER
);
1045 avail_pgs
= atomic_long_read(&nr_swap_pages
) / size
;
1049 n_goal
= min3((long)n_goal
, (long)SWAP_BATCH
, avail_pgs
);
1051 atomic_long_sub(n_goal
* size
, &nr_swap_pages
);
1053 spin_lock(&swap_avail_lock
);
1056 node
= numa_node_id();
1057 plist_for_each_entry_safe(si
, next
, &swap_avail_heads
[node
], avail_lists
[node
]) {
1058 /* requeue si to after same-priority siblings */
1059 plist_requeue(&si
->avail_lists
[node
], &swap_avail_heads
[node
]);
1060 spin_unlock(&swap_avail_lock
);
1061 spin_lock(&si
->lock
);
1062 if (!si
->highest_bit
|| !(si
->flags
& SWP_WRITEOK
)) {
1063 spin_lock(&swap_avail_lock
);
1064 if (plist_node_empty(&si
->avail_lists
[node
])) {
1065 spin_unlock(&si
->lock
);
1068 WARN(!si
->highest_bit
,
1069 "swap_info %d in list but !highest_bit\n",
1071 WARN(!(si
->flags
& SWP_WRITEOK
),
1072 "swap_info %d in list but !SWP_WRITEOK\n",
1074 __del_from_avail_list(si
);
1075 spin_unlock(&si
->lock
);
1078 if (size
== SWAPFILE_CLUSTER
) {
1079 if (!(si
->flags
& SWP_FS
))
1080 n_ret
= swap_alloc_cluster(si
, swp_entries
);
1082 n_ret
= scan_swap_map_slots(si
, SWAP_HAS_CACHE
,
1083 n_goal
, swp_entries
);
1084 spin_unlock(&si
->lock
);
1085 if (n_ret
|| size
== SWAPFILE_CLUSTER
)
1087 pr_debug("scan_swap_map of si %d failed to find offset\n",
1090 spin_lock(&swap_avail_lock
);
1093 * if we got here, it's likely that si was almost full before,
1094 * and since scan_swap_map() can drop the si->lock, multiple
1095 * callers probably all tried to get a page from the same si
1096 * and it filled up before we could get one; or, the si filled
1097 * up between us dropping swap_avail_lock and taking si->lock.
1098 * Since we dropped the swap_avail_lock, the swap_avail_head
1099 * list may have been modified; so if next is still in the
1100 * swap_avail_head list then try it, otherwise start over
1101 * if we have not gotten any slots.
1103 if (plist_node_empty(&next
->avail_lists
[node
]))
1107 spin_unlock(&swap_avail_lock
);
1111 atomic_long_add((long)(n_goal
- n_ret
) * size
,
1117 /* The only caller of this function is now suspend routine */
1118 swp_entry_t
get_swap_page_of_type(int type
)
1120 struct swap_info_struct
*si
= swap_type_to_swap_info(type
);
1126 spin_lock(&si
->lock
);
1127 if (si
->flags
& SWP_WRITEOK
) {
1128 atomic_long_dec(&nr_swap_pages
);
1129 /* This is called for allocating swap entry, not cache */
1130 offset
= scan_swap_map(si
, 1);
1132 spin_unlock(&si
->lock
);
1133 return swp_entry(type
, offset
);
1135 atomic_long_inc(&nr_swap_pages
);
1137 spin_unlock(&si
->lock
);
1139 return (swp_entry_t
) {0};
1142 static struct swap_info_struct
*__swap_info_get(swp_entry_t entry
)
1144 struct swap_info_struct
*p
;
1145 unsigned long offset
;
1149 p
= swp_swap_info(entry
);
1152 if (!(p
->flags
& SWP_USED
))
1154 offset
= swp_offset(entry
);
1155 if (offset
>= p
->max
)
1160 pr_err("swap_info_get: %s%08lx\n", Bad_offset
, entry
.val
);
1163 pr_err("swap_info_get: %s%08lx\n", Unused_file
, entry
.val
);
1166 pr_err("swap_info_get: %s%08lx\n", Bad_file
, entry
.val
);
1171 static struct swap_info_struct
*_swap_info_get(swp_entry_t entry
)
1173 struct swap_info_struct
*p
;
1175 p
= __swap_info_get(entry
);
1178 if (!p
->swap_map
[swp_offset(entry
)])
1183 pr_err("swap_info_get: %s%08lx\n", Unused_offset
, entry
.val
);
1189 static struct swap_info_struct
*swap_info_get(swp_entry_t entry
)
1191 struct swap_info_struct
*p
;
1193 p
= _swap_info_get(entry
);
1195 spin_lock(&p
->lock
);
1199 static struct swap_info_struct
*swap_info_get_cont(swp_entry_t entry
,
1200 struct swap_info_struct
*q
)
1202 struct swap_info_struct
*p
;
1204 p
= _swap_info_get(entry
);
1208 spin_unlock(&q
->lock
);
1210 spin_lock(&p
->lock
);
1215 static unsigned char __swap_entry_free_locked(struct swap_info_struct
*p
,
1216 unsigned long offset
,
1217 unsigned char usage
)
1219 unsigned char count
;
1220 unsigned char has_cache
;
1222 count
= p
->swap_map
[offset
];
1224 has_cache
= count
& SWAP_HAS_CACHE
;
1225 count
&= ~SWAP_HAS_CACHE
;
1227 if (usage
== SWAP_HAS_CACHE
) {
1228 VM_BUG_ON(!has_cache
);
1230 } else if (count
== SWAP_MAP_SHMEM
) {
1232 * Or we could insist on shmem.c using a special
1233 * swap_shmem_free() and free_shmem_swap_and_cache()...
1236 } else if ((count
& ~COUNT_CONTINUED
) <= SWAP_MAP_MAX
) {
1237 if (count
== COUNT_CONTINUED
) {
1238 if (swap_count_continued(p
, offset
, count
))
1239 count
= SWAP_MAP_MAX
| COUNT_CONTINUED
;
1241 count
= SWAP_MAP_MAX
;
1246 usage
= count
| has_cache
;
1247 p
->swap_map
[offset
] = usage
? : SWAP_HAS_CACHE
;
1253 * Check whether swap entry is valid in the swap device. If so,
1254 * return pointer to swap_info_struct, and keep the swap entry valid
1255 * via preventing the swap device from being swapoff, until
1256 * put_swap_device() is called. Otherwise return NULL.
1258 * The entirety of the RCU read critical section must come before the
1259 * return from or after the call to synchronize_rcu() in
1260 * enable_swap_info() or swapoff(). So if "si->flags & SWP_VALID" is
1261 * true, the si->map, si->cluster_info, etc. must be valid in the
1264 * Notice that swapoff or swapoff+swapon can still happen before the
1265 * rcu_read_lock() in get_swap_device() or after the rcu_read_unlock()
1266 * in put_swap_device() if there isn't any other way to prevent
1267 * swapoff, such as page lock, page table lock, etc. The caller must
1268 * be prepared for that. For example, the following situation is
1273 * ... swapoff+swapon
1274 * __read_swap_cache_async()
1275 * swapcache_prepare()
1276 * __swap_duplicate()
1278 * // verify PTE not changed
1280 * In __swap_duplicate(), the swap_map need to be checked before
1281 * changing partly because the specified swap entry may be for another
1282 * swap device which has been swapoff. And in do_swap_page(), after
1283 * the page is read from the swap device, the PTE is verified not
1284 * changed with the page table locked to check whether the swap device
1285 * has been swapoff or swapoff+swapon.
1287 struct swap_info_struct
*get_swap_device(swp_entry_t entry
)
1289 struct swap_info_struct
*si
;
1290 unsigned long offset
;
1294 si
= swp_swap_info(entry
);
1299 if (!(si
->flags
& SWP_VALID
))
1301 offset
= swp_offset(entry
);
1302 if (offset
>= si
->max
)
1307 pr_err("%s: %s%08lx\n", __func__
, Bad_file
, entry
.val
);
1315 static unsigned char __swap_entry_free(struct swap_info_struct
*p
,
1318 struct swap_cluster_info
*ci
;
1319 unsigned long offset
= swp_offset(entry
);
1320 unsigned char usage
;
1322 ci
= lock_cluster_or_swap_info(p
, offset
);
1323 usage
= __swap_entry_free_locked(p
, offset
, 1);
1324 unlock_cluster_or_swap_info(p
, ci
);
1326 free_swap_slot(entry
);
1331 static void swap_entry_free(struct swap_info_struct
*p
, swp_entry_t entry
)
1333 struct swap_cluster_info
*ci
;
1334 unsigned long offset
= swp_offset(entry
);
1335 unsigned char count
;
1337 ci
= lock_cluster(p
, offset
);
1338 count
= p
->swap_map
[offset
];
1339 VM_BUG_ON(count
!= SWAP_HAS_CACHE
);
1340 p
->swap_map
[offset
] = 0;
1341 dec_cluster_info_page(p
, p
->cluster_info
, offset
);
1344 mem_cgroup_uncharge_swap(entry
, 1);
1345 swap_range_free(p
, offset
, 1);
1349 * Caller has made sure that the swap device corresponding to entry
1350 * is still around or has not been recycled.
1352 void swap_free(swp_entry_t entry
)
1354 struct swap_info_struct
*p
;
1356 p
= _swap_info_get(entry
);
1358 __swap_entry_free(p
, entry
);
1362 * Called after dropping swapcache to decrease refcnt to swap entries.
1364 void put_swap_page(struct page
*page
, swp_entry_t entry
)
1366 unsigned long offset
= swp_offset(entry
);
1367 unsigned long idx
= offset
/ SWAPFILE_CLUSTER
;
1368 struct swap_cluster_info
*ci
;
1369 struct swap_info_struct
*si
;
1371 unsigned int i
, free_entries
= 0;
1373 int size
= swap_entry_size(hpage_nr_pages(page
));
1375 si
= _swap_info_get(entry
);
1379 ci
= lock_cluster_or_swap_info(si
, offset
);
1380 if (size
== SWAPFILE_CLUSTER
) {
1381 VM_BUG_ON(!cluster_is_huge(ci
));
1382 map
= si
->swap_map
+ offset
;
1383 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++) {
1385 VM_BUG_ON(!(val
& SWAP_HAS_CACHE
));
1386 if (val
== SWAP_HAS_CACHE
)
1389 cluster_clear_huge(ci
);
1390 if (free_entries
== SWAPFILE_CLUSTER
) {
1391 unlock_cluster_or_swap_info(si
, ci
);
1392 spin_lock(&si
->lock
);
1393 mem_cgroup_uncharge_swap(entry
, SWAPFILE_CLUSTER
);
1394 swap_free_cluster(si
, idx
);
1395 spin_unlock(&si
->lock
);
1399 for (i
= 0; i
< size
; i
++, entry
.val
++) {
1400 if (!__swap_entry_free_locked(si
, offset
+ i
, SWAP_HAS_CACHE
)) {
1401 unlock_cluster_or_swap_info(si
, ci
);
1402 free_swap_slot(entry
);
1405 lock_cluster_or_swap_info(si
, offset
);
1408 unlock_cluster_or_swap_info(si
, ci
);
1411 #ifdef CONFIG_THP_SWAP
1412 int split_swap_cluster(swp_entry_t entry
)
1414 struct swap_info_struct
*si
;
1415 struct swap_cluster_info
*ci
;
1416 unsigned long offset
= swp_offset(entry
);
1418 si
= _swap_info_get(entry
);
1421 ci
= lock_cluster(si
, offset
);
1422 cluster_clear_huge(ci
);
1428 static int swp_entry_cmp(const void *ent1
, const void *ent2
)
1430 const swp_entry_t
*e1
= ent1
, *e2
= ent2
;
1432 return (int)swp_type(*e1
) - (int)swp_type(*e2
);
1435 void swapcache_free_entries(swp_entry_t
*entries
, int n
)
1437 struct swap_info_struct
*p
, *prev
;
1447 * Sort swap entries by swap device, so each lock is only taken once.
1448 * nr_swapfiles isn't absolutely correct, but the overhead of sort() is
1449 * so low that it isn't necessary to optimize further.
1451 if (nr_swapfiles
> 1)
1452 sort(entries
, n
, sizeof(entries
[0]), swp_entry_cmp
, NULL
);
1453 for (i
= 0; i
< n
; ++i
) {
1454 p
= swap_info_get_cont(entries
[i
], prev
);
1456 swap_entry_free(p
, entries
[i
]);
1460 spin_unlock(&p
->lock
);
1464 * How many references to page are currently swapped out?
1465 * This does not give an exact answer when swap count is continued,
1466 * but does include the high COUNT_CONTINUED flag to allow for that.
1468 int page_swapcount(struct page
*page
)
1471 struct swap_info_struct
*p
;
1472 struct swap_cluster_info
*ci
;
1474 unsigned long offset
;
1476 entry
.val
= page_private(page
);
1477 p
= _swap_info_get(entry
);
1479 offset
= swp_offset(entry
);
1480 ci
= lock_cluster_or_swap_info(p
, offset
);
1481 count
= swap_count(p
->swap_map
[offset
]);
1482 unlock_cluster_or_swap_info(p
, ci
);
1487 int __swap_count(swp_entry_t entry
)
1489 struct swap_info_struct
*si
;
1490 pgoff_t offset
= swp_offset(entry
);
1493 si
= get_swap_device(entry
);
1495 count
= swap_count(si
->swap_map
[offset
]);
1496 put_swap_device(si
);
1501 static int swap_swapcount(struct swap_info_struct
*si
, swp_entry_t entry
)
1504 pgoff_t offset
= swp_offset(entry
);
1505 struct swap_cluster_info
*ci
;
1507 ci
= lock_cluster_or_swap_info(si
, offset
);
1508 count
= swap_count(si
->swap_map
[offset
]);
1509 unlock_cluster_or_swap_info(si
, ci
);
1514 * How many references to @entry are currently swapped out?
1515 * This does not give an exact answer when swap count is continued,
1516 * but does include the high COUNT_CONTINUED flag to allow for that.
1518 int __swp_swapcount(swp_entry_t entry
)
1521 struct swap_info_struct
*si
;
1523 si
= get_swap_device(entry
);
1525 count
= swap_swapcount(si
, entry
);
1526 put_swap_device(si
);
1532 * How many references to @entry are currently swapped out?
1533 * This considers COUNT_CONTINUED so it returns exact answer.
1535 int swp_swapcount(swp_entry_t entry
)
1537 int count
, tmp_count
, n
;
1538 struct swap_info_struct
*p
;
1539 struct swap_cluster_info
*ci
;
1544 p
= _swap_info_get(entry
);
1548 offset
= swp_offset(entry
);
1550 ci
= lock_cluster_or_swap_info(p
, offset
);
1552 count
= swap_count(p
->swap_map
[offset
]);
1553 if (!(count
& COUNT_CONTINUED
))
1556 count
&= ~COUNT_CONTINUED
;
1557 n
= SWAP_MAP_MAX
+ 1;
1559 page
= vmalloc_to_page(p
->swap_map
+ offset
);
1560 offset
&= ~PAGE_MASK
;
1561 VM_BUG_ON(page_private(page
) != SWP_CONTINUED
);
1564 page
= list_next_entry(page
, lru
);
1565 map
= kmap_atomic(page
);
1566 tmp_count
= map
[offset
];
1569 count
+= (tmp_count
& ~COUNT_CONTINUED
) * n
;
1570 n
*= (SWAP_CONT_MAX
+ 1);
1571 } while (tmp_count
& COUNT_CONTINUED
);
1573 unlock_cluster_or_swap_info(p
, ci
);
1577 static bool swap_page_trans_huge_swapped(struct swap_info_struct
*si
,
1580 struct swap_cluster_info
*ci
;
1581 unsigned char *map
= si
->swap_map
;
1582 unsigned long roffset
= swp_offset(entry
);
1583 unsigned long offset
= round_down(roffset
, SWAPFILE_CLUSTER
);
1587 ci
= lock_cluster_or_swap_info(si
, offset
);
1588 if (!ci
|| !cluster_is_huge(ci
)) {
1589 if (swap_count(map
[roffset
]))
1593 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++) {
1594 if (swap_count(map
[offset
+ i
])) {
1600 unlock_cluster_or_swap_info(si
, ci
);
1604 static bool page_swapped(struct page
*page
)
1607 struct swap_info_struct
*si
;
1609 if (!IS_ENABLED(CONFIG_THP_SWAP
) || likely(!PageTransCompound(page
)))
1610 return page_swapcount(page
) != 0;
1612 page
= compound_head(page
);
1613 entry
.val
= page_private(page
);
1614 si
= _swap_info_get(entry
);
1616 return swap_page_trans_huge_swapped(si
, entry
);
1620 static int page_trans_huge_map_swapcount(struct page
*page
, int *total_mapcount
,
1621 int *total_swapcount
)
1623 int i
, map_swapcount
, _total_mapcount
, _total_swapcount
;
1624 unsigned long offset
= 0;
1625 struct swap_info_struct
*si
;
1626 struct swap_cluster_info
*ci
= NULL
;
1627 unsigned char *map
= NULL
;
1628 int mapcount
, swapcount
= 0;
1630 /* hugetlbfs shouldn't call it */
1631 VM_BUG_ON_PAGE(PageHuge(page
), page
);
1633 if (!IS_ENABLED(CONFIG_THP_SWAP
) || likely(!PageTransCompound(page
))) {
1634 mapcount
= page_trans_huge_mapcount(page
, total_mapcount
);
1635 if (PageSwapCache(page
))
1636 swapcount
= page_swapcount(page
);
1637 if (total_swapcount
)
1638 *total_swapcount
= swapcount
;
1639 return mapcount
+ swapcount
;
1642 page
= compound_head(page
);
1644 _total_mapcount
= _total_swapcount
= map_swapcount
= 0;
1645 if (PageSwapCache(page
)) {
1648 entry
.val
= page_private(page
);
1649 si
= _swap_info_get(entry
);
1652 offset
= swp_offset(entry
);
1656 ci
= lock_cluster(si
, offset
);
1657 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1658 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
1659 _total_mapcount
+= mapcount
;
1661 swapcount
= swap_count(map
[offset
+ i
]);
1662 _total_swapcount
+= swapcount
;
1664 map_swapcount
= max(map_swapcount
, mapcount
+ swapcount
);
1667 if (PageDoubleMap(page
)) {
1669 _total_mapcount
-= HPAGE_PMD_NR
;
1671 mapcount
= compound_mapcount(page
);
1672 map_swapcount
+= mapcount
;
1673 _total_mapcount
+= mapcount
;
1675 *total_mapcount
= _total_mapcount
;
1676 if (total_swapcount
)
1677 *total_swapcount
= _total_swapcount
;
1679 return map_swapcount
;
1683 * We can write to an anon page without COW if there are no other references
1684 * to it. And as a side-effect, free up its swap: because the old content
1685 * on disk will never be read, and seeking back there to write new content
1686 * later would only waste time away from clustering.
1688 * NOTE: total_map_swapcount should not be relied upon by the caller if
1689 * reuse_swap_page() returns false, but it may be always overwritten
1690 * (see the other implementation for CONFIG_SWAP=n).
1692 bool reuse_swap_page(struct page
*page
, int *total_map_swapcount
)
1694 int count
, total_mapcount
, total_swapcount
;
1696 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1697 if (unlikely(PageKsm(page
)))
1699 count
= page_trans_huge_map_swapcount(page
, &total_mapcount
,
1701 if (total_map_swapcount
)
1702 *total_map_swapcount
= total_mapcount
+ total_swapcount
;
1703 if (count
== 1 && PageSwapCache(page
) &&
1704 (likely(!PageTransCompound(page
)) ||
1705 /* The remaining swap count will be freed soon */
1706 total_swapcount
== page_swapcount(page
))) {
1707 if (!PageWriteback(page
)) {
1708 page
= compound_head(page
);
1709 delete_from_swap_cache(page
);
1713 struct swap_info_struct
*p
;
1715 entry
.val
= page_private(page
);
1716 p
= swap_info_get(entry
);
1717 if (p
->flags
& SWP_STABLE_WRITES
) {
1718 spin_unlock(&p
->lock
);
1721 spin_unlock(&p
->lock
);
1729 * If swap is getting full, or if there are no more mappings of this page,
1730 * then try_to_free_swap is called to free its swap space.
1732 int try_to_free_swap(struct page
*page
)
1734 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1736 if (!PageSwapCache(page
))
1738 if (PageWriteback(page
))
1740 if (page_swapped(page
))
1744 * Once hibernation has begun to create its image of memory,
1745 * there's a danger that one of the calls to try_to_free_swap()
1746 * - most probably a call from __try_to_reclaim_swap() while
1747 * hibernation is allocating its own swap pages for the image,
1748 * but conceivably even a call from memory reclaim - will free
1749 * the swap from a page which has already been recorded in the
1750 * image as a clean swapcache page, and then reuse its swap for
1751 * another page of the image. On waking from hibernation, the
1752 * original page might be freed under memory pressure, then
1753 * later read back in from swap, now with the wrong data.
1755 * Hibernation suspends storage while it is writing the image
1756 * to disk so check that here.
1758 if (pm_suspended_storage())
1761 page
= compound_head(page
);
1762 delete_from_swap_cache(page
);
1768 * Free the swap entry like above, but also try to
1769 * free the page cache entry if it is the last user.
1771 int free_swap_and_cache(swp_entry_t entry
)
1773 struct swap_info_struct
*p
;
1774 unsigned char count
;
1776 if (non_swap_entry(entry
))
1779 p
= _swap_info_get(entry
);
1781 count
= __swap_entry_free(p
, entry
);
1782 if (count
== SWAP_HAS_CACHE
&&
1783 !swap_page_trans_huge_swapped(p
, entry
))
1784 __try_to_reclaim_swap(p
, swp_offset(entry
),
1785 TTRS_UNMAPPED
| TTRS_FULL
);
1790 #ifdef CONFIG_HIBERNATION
1792 * Find the swap type that corresponds to given device (if any).
1794 * @offset - number of the PAGE_SIZE-sized block of the device, starting
1795 * from 0, in which the swap header is expected to be located.
1797 * This is needed for the suspend to disk (aka swsusp).
1799 int swap_type_of(dev_t device
, sector_t offset
, struct block_device
**bdev_p
)
1801 struct block_device
*bdev
= NULL
;
1805 bdev
= bdget(device
);
1807 spin_lock(&swap_lock
);
1808 for (type
= 0; type
< nr_swapfiles
; type
++) {
1809 struct swap_info_struct
*sis
= swap_info
[type
];
1811 if (!(sis
->flags
& SWP_WRITEOK
))
1816 *bdev_p
= bdgrab(sis
->bdev
);
1818 spin_unlock(&swap_lock
);
1821 if (bdev
== sis
->bdev
) {
1822 struct swap_extent
*se
= first_se(sis
);
1824 if (se
->start_block
== offset
) {
1826 *bdev_p
= bdgrab(sis
->bdev
);
1828 spin_unlock(&swap_lock
);
1834 spin_unlock(&swap_lock
);
1842 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
1843 * corresponding to given index in swap_info (swap type).
1845 sector_t
swapdev_block(int type
, pgoff_t offset
)
1847 struct block_device
*bdev
;
1848 struct swap_info_struct
*si
= swap_type_to_swap_info(type
);
1850 if (!si
|| !(si
->flags
& SWP_WRITEOK
))
1852 return map_swap_entry(swp_entry(type
, offset
), &bdev
);
1856 * Return either the total number of swap pages of given type, or the number
1857 * of free pages of that type (depending on @free)
1859 * This is needed for software suspend
1861 unsigned int count_swap_pages(int type
, int free
)
1865 spin_lock(&swap_lock
);
1866 if ((unsigned int)type
< nr_swapfiles
) {
1867 struct swap_info_struct
*sis
= swap_info
[type
];
1869 spin_lock(&sis
->lock
);
1870 if (sis
->flags
& SWP_WRITEOK
) {
1873 n
-= sis
->inuse_pages
;
1875 spin_unlock(&sis
->lock
);
1877 spin_unlock(&swap_lock
);
1880 #endif /* CONFIG_HIBERNATION */
1882 static inline int pte_same_as_swp(pte_t pte
, pte_t swp_pte
)
1884 return pte_same(pte_swp_clear_soft_dirty(pte
), swp_pte
);
1888 * No need to decide whether this PTE shares the swap entry with others,
1889 * just let do_wp_page work it out if a write is requested later - to
1890 * force COW, vm_page_prot omits write permission from any private vma.
1892 static int unuse_pte(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1893 unsigned long addr
, swp_entry_t entry
, struct page
*page
)
1895 struct page
*swapcache
;
1901 page
= ksm_might_need_to_copy(page
, vma
, addr
);
1902 if (unlikely(!page
))
1905 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
1906 if (unlikely(!pte_same_as_swp(*pte
, swp_entry_to_pte(entry
)))) {
1911 dec_mm_counter(vma
->vm_mm
, MM_SWAPENTS
);
1912 inc_mm_counter(vma
->vm_mm
, MM_ANONPAGES
);
1914 set_pte_at(vma
->vm_mm
, addr
, pte
,
1915 pte_mkold(mk_pte(page
, vma
->vm_page_prot
)));
1916 if (page
== swapcache
) {
1917 page_add_anon_rmap(page
, vma
, addr
, false);
1918 } else { /* ksm created a completely new copy */
1919 page_add_new_anon_rmap(page
, vma
, addr
, false);
1920 lru_cache_add_inactive_or_unevictable(page
, vma
);
1924 * Move the page to the active list so it is not
1925 * immediately swapped out again after swapon.
1927 activate_page(page
);
1929 pte_unmap_unlock(pte
, ptl
);
1930 if (page
!= swapcache
) {
1937 static int unuse_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1938 unsigned long addr
, unsigned long end
,
1939 unsigned int type
, bool frontswap
,
1940 unsigned long *fs_pages_to_unuse
)
1945 struct swap_info_struct
*si
;
1946 unsigned long offset
;
1948 volatile unsigned char *swap_map
;
1950 si
= swap_info
[type
];
1951 pte
= pte_offset_map(pmd
, addr
);
1953 struct vm_fault vmf
;
1955 if (!is_swap_pte(*pte
))
1958 entry
= pte_to_swp_entry(*pte
);
1959 if (swp_type(entry
) != type
)
1962 offset
= swp_offset(entry
);
1963 if (frontswap
&& !frontswap_test(si
, offset
))
1967 swap_map
= &si
->swap_map
[offset
];
1968 page
= lookup_swap_cache(entry
, vma
, addr
);
1973 page
= swapin_readahead(entry
, GFP_HIGHUSER_MOVABLE
,
1977 if (*swap_map
== 0 || *swap_map
== SWAP_MAP_BAD
)
1983 wait_on_page_writeback(page
);
1984 ret
= unuse_pte(vma
, pmd
, addr
, entry
, page
);
1991 try_to_free_swap(page
);
1995 if (*fs_pages_to_unuse
&& !--(*fs_pages_to_unuse
)) {
1996 ret
= FRONTSWAP_PAGES_UNUSED
;
2000 pte
= pte_offset_map(pmd
, addr
);
2001 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
2009 static inline int unuse_pmd_range(struct vm_area_struct
*vma
, pud_t
*pud
,
2010 unsigned long addr
, unsigned long end
,
2011 unsigned int type
, bool frontswap
,
2012 unsigned long *fs_pages_to_unuse
)
2018 pmd
= pmd_offset(pud
, addr
);
2021 next
= pmd_addr_end(addr
, end
);
2022 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
2024 ret
= unuse_pte_range(vma
, pmd
, addr
, next
, type
,
2025 frontswap
, fs_pages_to_unuse
);
2028 } while (pmd
++, addr
= next
, addr
!= end
);
2032 static inline int unuse_pud_range(struct vm_area_struct
*vma
, p4d_t
*p4d
,
2033 unsigned long addr
, unsigned long end
,
2034 unsigned int type
, bool frontswap
,
2035 unsigned long *fs_pages_to_unuse
)
2041 pud
= pud_offset(p4d
, addr
);
2043 next
= pud_addr_end(addr
, end
);
2044 if (pud_none_or_clear_bad(pud
))
2046 ret
= unuse_pmd_range(vma
, pud
, addr
, next
, type
,
2047 frontswap
, fs_pages_to_unuse
);
2050 } while (pud
++, addr
= next
, addr
!= end
);
2054 static inline int unuse_p4d_range(struct vm_area_struct
*vma
, pgd_t
*pgd
,
2055 unsigned long addr
, unsigned long end
,
2056 unsigned int type
, bool frontswap
,
2057 unsigned long *fs_pages_to_unuse
)
2063 p4d
= p4d_offset(pgd
, addr
);
2065 next
= p4d_addr_end(addr
, end
);
2066 if (p4d_none_or_clear_bad(p4d
))
2068 ret
= unuse_pud_range(vma
, p4d
, addr
, next
, type
,
2069 frontswap
, fs_pages_to_unuse
);
2072 } while (p4d
++, addr
= next
, addr
!= end
);
2076 static int unuse_vma(struct vm_area_struct
*vma
, unsigned int type
,
2077 bool frontswap
, unsigned long *fs_pages_to_unuse
)
2080 unsigned long addr
, end
, next
;
2083 addr
= vma
->vm_start
;
2086 pgd
= pgd_offset(vma
->vm_mm
, addr
);
2088 next
= pgd_addr_end(addr
, end
);
2089 if (pgd_none_or_clear_bad(pgd
))
2091 ret
= unuse_p4d_range(vma
, pgd
, addr
, next
, type
,
2092 frontswap
, fs_pages_to_unuse
);
2095 } while (pgd
++, addr
= next
, addr
!= end
);
2099 static int unuse_mm(struct mm_struct
*mm
, unsigned int type
,
2100 bool frontswap
, unsigned long *fs_pages_to_unuse
)
2102 struct vm_area_struct
*vma
;
2106 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2107 if (vma
->anon_vma
) {
2108 ret
= unuse_vma(vma
, type
, frontswap
,
2115 mmap_read_unlock(mm
);
2120 * Scan swap_map (or frontswap_map if frontswap parameter is true)
2121 * from current position to next entry still in use. Return 0
2122 * if there are no inuse entries after prev till end of the map.
2124 static unsigned int find_next_to_unuse(struct swap_info_struct
*si
,
2125 unsigned int prev
, bool frontswap
)
2128 unsigned char count
;
2131 * No need for swap_lock here: we're just looking
2132 * for whether an entry is in use, not modifying it; false
2133 * hits are okay, and sys_swapoff() has already prevented new
2134 * allocations from this area (while holding swap_lock).
2136 for (i
= prev
+ 1; i
< si
->max
; i
++) {
2137 count
= READ_ONCE(si
->swap_map
[i
]);
2138 if (count
&& swap_count(count
) != SWAP_MAP_BAD
)
2139 if (!frontswap
|| frontswap_test(si
, i
))
2141 if ((i
% LATENCY_LIMIT
) == 0)
2152 * If the boolean frontswap is true, only unuse pages_to_unuse pages;
2153 * pages_to_unuse==0 means all pages; ignored if frontswap is false
2155 int try_to_unuse(unsigned int type
, bool frontswap
,
2156 unsigned long pages_to_unuse
)
2158 struct mm_struct
*prev_mm
;
2159 struct mm_struct
*mm
;
2160 struct list_head
*p
;
2162 struct swap_info_struct
*si
= swap_info
[type
];
2167 if (!READ_ONCE(si
->inuse_pages
))
2174 retval
= shmem_unuse(type
, frontswap
, &pages_to_unuse
);
2181 spin_lock(&mmlist_lock
);
2182 p
= &init_mm
.mmlist
;
2183 while (READ_ONCE(si
->inuse_pages
) &&
2184 !signal_pending(current
) &&
2185 (p
= p
->next
) != &init_mm
.mmlist
) {
2187 mm
= list_entry(p
, struct mm_struct
, mmlist
);
2188 if (!mmget_not_zero(mm
))
2190 spin_unlock(&mmlist_lock
);
2193 retval
= unuse_mm(mm
, type
, frontswap
, &pages_to_unuse
);
2201 * Make sure that we aren't completely killing
2202 * interactive performance.
2205 spin_lock(&mmlist_lock
);
2207 spin_unlock(&mmlist_lock
);
2212 while (READ_ONCE(si
->inuse_pages
) &&
2213 !signal_pending(current
) &&
2214 (i
= find_next_to_unuse(si
, i
, frontswap
)) != 0) {
2216 entry
= swp_entry(type
, i
);
2217 page
= find_get_page(swap_address_space(entry
), i
);
2222 * It is conceivable that a racing task removed this page from
2223 * swap cache just before we acquired the page lock. The page
2224 * might even be back in swap cache on another swap area. But
2225 * that is okay, try_to_free_swap() only removes stale pages.
2228 wait_on_page_writeback(page
);
2229 try_to_free_swap(page
);
2234 * For frontswap, we just need to unuse pages_to_unuse, if
2235 * it was specified. Need not check frontswap again here as
2236 * we already zeroed out pages_to_unuse if not frontswap.
2238 if (pages_to_unuse
&& --pages_to_unuse
== 0)
2243 * Lets check again to see if there are still swap entries in the map.
2244 * If yes, we would need to do retry the unuse logic again.
2245 * Under global memory pressure, swap entries can be reinserted back
2246 * into process space after the mmlist loop above passes over them.
2248 * Limit the number of retries? No: when mmget_not_zero() above fails,
2249 * that mm is likely to be freeing swap from exit_mmap(), which proceeds
2250 * at its own independent pace; and even shmem_writepage() could have
2251 * been preempted after get_swap_page(), temporarily hiding that swap.
2252 * It's easy and robust (though cpu-intensive) just to keep retrying.
2254 if (READ_ONCE(si
->inuse_pages
)) {
2255 if (!signal_pending(current
))
2260 return (retval
== FRONTSWAP_PAGES_UNUSED
) ? 0 : retval
;
2264 * After a successful try_to_unuse, if no swap is now in use, we know
2265 * we can empty the mmlist. swap_lock must be held on entry and exit.
2266 * Note that mmlist_lock nests inside swap_lock, and an mm must be
2267 * added to the mmlist just after page_duplicate - before would be racy.
2269 static void drain_mmlist(void)
2271 struct list_head
*p
, *next
;
2274 for (type
= 0; type
< nr_swapfiles
; type
++)
2275 if (swap_info
[type
]->inuse_pages
)
2277 spin_lock(&mmlist_lock
);
2278 list_for_each_safe(p
, next
, &init_mm
.mmlist
)
2280 spin_unlock(&mmlist_lock
);
2284 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
2285 * corresponds to page offset for the specified swap entry.
2286 * Note that the type of this function is sector_t, but it returns page offset
2287 * into the bdev, not sector offset.
2289 static sector_t
map_swap_entry(swp_entry_t entry
, struct block_device
**bdev
)
2291 struct swap_info_struct
*sis
;
2292 struct swap_extent
*se
;
2295 sis
= swp_swap_info(entry
);
2298 offset
= swp_offset(entry
);
2299 se
= offset_to_swap_extent(sis
, offset
);
2300 return se
->start_block
+ (offset
- se
->start_page
);
2304 * Returns the page offset into bdev for the specified page's swap entry.
2306 sector_t
map_swap_page(struct page
*page
, struct block_device
**bdev
)
2309 entry
.val
= page_private(page
);
2310 return map_swap_entry(entry
, bdev
);
2314 * Free all of a swapdev's extent information
2316 static void destroy_swap_extents(struct swap_info_struct
*sis
)
2318 while (!RB_EMPTY_ROOT(&sis
->swap_extent_root
)) {
2319 struct rb_node
*rb
= sis
->swap_extent_root
.rb_node
;
2320 struct swap_extent
*se
= rb_entry(rb
, struct swap_extent
, rb_node
);
2322 rb_erase(rb
, &sis
->swap_extent_root
);
2326 if (sis
->flags
& SWP_ACTIVATED
) {
2327 struct file
*swap_file
= sis
->swap_file
;
2328 struct address_space
*mapping
= swap_file
->f_mapping
;
2330 sis
->flags
&= ~SWP_ACTIVATED
;
2331 if (mapping
->a_ops
->swap_deactivate
)
2332 mapping
->a_ops
->swap_deactivate(swap_file
);
2337 * Add a block range (and the corresponding page range) into this swapdev's
2340 * This function rather assumes that it is called in ascending page order.
2343 add_swap_extent(struct swap_info_struct
*sis
, unsigned long start_page
,
2344 unsigned long nr_pages
, sector_t start_block
)
2346 struct rb_node
**link
= &sis
->swap_extent_root
.rb_node
, *parent
= NULL
;
2347 struct swap_extent
*se
;
2348 struct swap_extent
*new_se
;
2351 * place the new node at the right most since the
2352 * function is called in ascending page order.
2356 link
= &parent
->rb_right
;
2360 se
= rb_entry(parent
, struct swap_extent
, rb_node
);
2361 BUG_ON(se
->start_page
+ se
->nr_pages
!= start_page
);
2362 if (se
->start_block
+ se
->nr_pages
== start_block
) {
2364 se
->nr_pages
+= nr_pages
;
2369 /* No merge, insert a new extent. */
2370 new_se
= kmalloc(sizeof(*se
), GFP_KERNEL
);
2373 new_se
->start_page
= start_page
;
2374 new_se
->nr_pages
= nr_pages
;
2375 new_se
->start_block
= start_block
;
2377 rb_link_node(&new_se
->rb_node
, parent
, link
);
2378 rb_insert_color(&new_se
->rb_node
, &sis
->swap_extent_root
);
2381 EXPORT_SYMBOL_GPL(add_swap_extent
);
2384 * A `swap extent' is a simple thing which maps a contiguous range of pages
2385 * onto a contiguous range of disk blocks. An ordered list of swap extents
2386 * is built at swapon time and is then used at swap_writepage/swap_readpage
2387 * time for locating where on disk a page belongs.
2389 * If the swapfile is an S_ISBLK block device, a single extent is installed.
2390 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
2391 * swap files identically.
2393 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
2394 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
2395 * swapfiles are handled *identically* after swapon time.
2397 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
2398 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
2399 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
2400 * requirements, they are simply tossed out - we will never use those blocks
2403 * For all swap devices we set S_SWAPFILE across the life of the swapon. This
2404 * prevents users from writing to the swap device, which will corrupt memory.
2406 * The amount of disk space which a single swap extent represents varies.
2407 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
2408 * extents in the list. To avoid much list walking, we cache the previous
2409 * search location in `curr_swap_extent', and start new searches from there.
2410 * This is extremely effective. The average number of iterations in
2411 * map_swap_page() has been measured at about 0.3 per page. - akpm.
2413 static int setup_swap_extents(struct swap_info_struct
*sis
, sector_t
*span
)
2415 struct file
*swap_file
= sis
->swap_file
;
2416 struct address_space
*mapping
= swap_file
->f_mapping
;
2417 struct inode
*inode
= mapping
->host
;
2420 if (S_ISBLK(inode
->i_mode
)) {
2421 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
2426 if (mapping
->a_ops
->swap_activate
) {
2427 ret
= mapping
->a_ops
->swap_activate(sis
, swap_file
, span
);
2429 sis
->flags
|= SWP_ACTIVATED
;
2431 sis
->flags
|= SWP_FS
;
2432 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
2438 return generic_swapfile_activate(sis
, swap_file
, span
);
2441 static int swap_node(struct swap_info_struct
*p
)
2443 struct block_device
*bdev
;
2448 bdev
= p
->swap_file
->f_inode
->i_sb
->s_bdev
;
2450 return bdev
? bdev
->bd_disk
->node_id
: NUMA_NO_NODE
;
2453 static void setup_swap_info(struct swap_info_struct
*p
, int prio
,
2454 unsigned char *swap_map
,
2455 struct swap_cluster_info
*cluster_info
)
2462 p
->prio
= --least_priority
;
2464 * the plist prio is negated because plist ordering is
2465 * low-to-high, while swap ordering is high-to-low
2467 p
->list
.prio
= -p
->prio
;
2470 p
->avail_lists
[i
].prio
= -p
->prio
;
2472 if (swap_node(p
) == i
)
2473 p
->avail_lists
[i
].prio
= 1;
2475 p
->avail_lists
[i
].prio
= -p
->prio
;
2478 p
->swap_map
= swap_map
;
2479 p
->cluster_info
= cluster_info
;
2482 static void _enable_swap_info(struct swap_info_struct
*p
)
2484 p
->flags
|= SWP_WRITEOK
| SWP_VALID
;
2485 atomic_long_add(p
->pages
, &nr_swap_pages
);
2486 total_swap_pages
+= p
->pages
;
2488 assert_spin_locked(&swap_lock
);
2490 * both lists are plists, and thus priority ordered.
2491 * swap_active_head needs to be priority ordered for swapoff(),
2492 * which on removal of any swap_info_struct with an auto-assigned
2493 * (i.e. negative) priority increments the auto-assigned priority
2494 * of any lower-priority swap_info_structs.
2495 * swap_avail_head needs to be priority ordered for get_swap_page(),
2496 * which allocates swap pages from the highest available priority
2499 plist_add(&p
->list
, &swap_active_head
);
2500 add_to_avail_list(p
);
2503 static void enable_swap_info(struct swap_info_struct
*p
, int prio
,
2504 unsigned char *swap_map
,
2505 struct swap_cluster_info
*cluster_info
,
2506 unsigned long *frontswap_map
)
2508 frontswap_init(p
->type
, frontswap_map
);
2509 spin_lock(&swap_lock
);
2510 spin_lock(&p
->lock
);
2511 setup_swap_info(p
, prio
, swap_map
, cluster_info
);
2512 spin_unlock(&p
->lock
);
2513 spin_unlock(&swap_lock
);
2515 * Guarantee swap_map, cluster_info, etc. fields are valid
2516 * between get/put_swap_device() if SWP_VALID bit is set
2519 spin_lock(&swap_lock
);
2520 spin_lock(&p
->lock
);
2521 _enable_swap_info(p
);
2522 spin_unlock(&p
->lock
);
2523 spin_unlock(&swap_lock
);
2526 static void reinsert_swap_info(struct swap_info_struct
*p
)
2528 spin_lock(&swap_lock
);
2529 spin_lock(&p
->lock
);
2530 setup_swap_info(p
, p
->prio
, p
->swap_map
, p
->cluster_info
);
2531 _enable_swap_info(p
);
2532 spin_unlock(&p
->lock
);
2533 spin_unlock(&swap_lock
);
2536 bool has_usable_swap(void)
2540 spin_lock(&swap_lock
);
2541 if (plist_head_empty(&swap_active_head
))
2543 spin_unlock(&swap_lock
);
2547 SYSCALL_DEFINE1(swapoff
, const char __user
*, specialfile
)
2549 struct swap_info_struct
*p
= NULL
;
2550 unsigned char *swap_map
;
2551 struct swap_cluster_info
*cluster_info
;
2552 unsigned long *frontswap_map
;
2553 struct file
*swap_file
, *victim
;
2554 struct address_space
*mapping
;
2555 struct inode
*inode
;
2556 struct filename
*pathname
;
2558 unsigned int old_block_size
;
2560 if (!capable(CAP_SYS_ADMIN
))
2563 BUG_ON(!current
->mm
);
2565 pathname
= getname(specialfile
);
2566 if (IS_ERR(pathname
))
2567 return PTR_ERR(pathname
);
2569 victim
= file_open_name(pathname
, O_RDWR
|O_LARGEFILE
, 0);
2570 err
= PTR_ERR(victim
);
2574 mapping
= victim
->f_mapping
;
2575 spin_lock(&swap_lock
);
2576 plist_for_each_entry(p
, &swap_active_head
, list
) {
2577 if (p
->flags
& SWP_WRITEOK
) {
2578 if (p
->swap_file
->f_mapping
== mapping
) {
2586 spin_unlock(&swap_lock
);
2589 if (!security_vm_enough_memory_mm(current
->mm
, p
->pages
))
2590 vm_unacct_memory(p
->pages
);
2593 spin_unlock(&swap_lock
);
2596 del_from_avail_list(p
);
2597 spin_lock(&p
->lock
);
2599 struct swap_info_struct
*si
= p
;
2602 plist_for_each_entry_continue(si
, &swap_active_head
, list
) {
2605 for_each_node(nid
) {
2606 if (si
->avail_lists
[nid
].prio
!= 1)
2607 si
->avail_lists
[nid
].prio
--;
2612 plist_del(&p
->list
, &swap_active_head
);
2613 atomic_long_sub(p
->pages
, &nr_swap_pages
);
2614 total_swap_pages
-= p
->pages
;
2615 p
->flags
&= ~SWP_WRITEOK
;
2616 spin_unlock(&p
->lock
);
2617 spin_unlock(&swap_lock
);
2619 disable_swap_slots_cache_lock();
2621 set_current_oom_origin();
2622 err
= try_to_unuse(p
->type
, false, 0); /* force unuse all pages */
2623 clear_current_oom_origin();
2626 /* re-insert swap space back into swap_list */
2627 reinsert_swap_info(p
);
2628 reenable_swap_slots_cache_unlock();
2632 reenable_swap_slots_cache_unlock();
2634 spin_lock(&swap_lock
);
2635 spin_lock(&p
->lock
);
2636 p
->flags
&= ~SWP_VALID
; /* mark swap device as invalid */
2637 spin_unlock(&p
->lock
);
2638 spin_unlock(&swap_lock
);
2640 * wait for swap operations protected by get/put_swap_device()
2645 flush_work(&p
->discard_work
);
2647 destroy_swap_extents(p
);
2648 if (p
->flags
& SWP_CONTINUED
)
2649 free_swap_count_continuations(p
);
2651 if (!p
->bdev
|| !blk_queue_nonrot(bdev_get_queue(p
->bdev
)))
2652 atomic_dec(&nr_rotate_swap
);
2654 mutex_lock(&swapon_mutex
);
2655 spin_lock(&swap_lock
);
2656 spin_lock(&p
->lock
);
2659 /* wait for anyone still in scan_swap_map */
2660 p
->highest_bit
= 0; /* cuts scans short */
2661 while (p
->flags
>= SWP_SCANNING
) {
2662 spin_unlock(&p
->lock
);
2663 spin_unlock(&swap_lock
);
2664 schedule_timeout_uninterruptible(1);
2665 spin_lock(&swap_lock
);
2666 spin_lock(&p
->lock
);
2669 swap_file
= p
->swap_file
;
2670 old_block_size
= p
->old_block_size
;
2671 p
->swap_file
= NULL
;
2673 swap_map
= p
->swap_map
;
2675 cluster_info
= p
->cluster_info
;
2676 p
->cluster_info
= NULL
;
2677 frontswap_map
= frontswap_map_get(p
);
2678 spin_unlock(&p
->lock
);
2679 spin_unlock(&swap_lock
);
2680 frontswap_invalidate_area(p
->type
);
2681 frontswap_map_set(p
, NULL
);
2682 mutex_unlock(&swapon_mutex
);
2683 free_percpu(p
->percpu_cluster
);
2684 p
->percpu_cluster
= NULL
;
2685 free_percpu(p
->cluster_next_cpu
);
2686 p
->cluster_next_cpu
= NULL
;
2688 kvfree(cluster_info
);
2689 kvfree(frontswap_map
);
2690 /* Destroy swap account information */
2691 swap_cgroup_swapoff(p
->type
);
2692 exit_swap_address_space(p
->type
);
2694 inode
= mapping
->host
;
2695 if (S_ISBLK(inode
->i_mode
)) {
2696 struct block_device
*bdev
= I_BDEV(inode
);
2698 set_blocksize(bdev
, old_block_size
);
2699 blkdev_put(bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
2703 inode
->i_flags
&= ~S_SWAPFILE
;
2704 inode_unlock(inode
);
2705 filp_close(swap_file
, NULL
);
2708 * Clear the SWP_USED flag after all resources are freed so that swapon
2709 * can reuse this swap_info in alloc_swap_info() safely. It is ok to
2710 * not hold p->lock after we cleared its SWP_WRITEOK.
2712 spin_lock(&swap_lock
);
2714 spin_unlock(&swap_lock
);
2717 atomic_inc(&proc_poll_event
);
2718 wake_up_interruptible(&proc_poll_wait
);
2721 filp_close(victim
, NULL
);
2727 #ifdef CONFIG_PROC_FS
2728 static __poll_t
swaps_poll(struct file
*file
, poll_table
*wait
)
2730 struct seq_file
*seq
= file
->private_data
;
2732 poll_wait(file
, &proc_poll_wait
, wait
);
2734 if (seq
->poll_event
!= atomic_read(&proc_poll_event
)) {
2735 seq
->poll_event
= atomic_read(&proc_poll_event
);
2736 return EPOLLIN
| EPOLLRDNORM
| EPOLLERR
| EPOLLPRI
;
2739 return EPOLLIN
| EPOLLRDNORM
;
2743 static void *swap_start(struct seq_file
*swap
, loff_t
*pos
)
2745 struct swap_info_struct
*si
;
2749 mutex_lock(&swapon_mutex
);
2752 return SEQ_START_TOKEN
;
2754 for (type
= 0; (si
= swap_type_to_swap_info(type
)); type
++) {
2755 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
2764 static void *swap_next(struct seq_file
*swap
, void *v
, loff_t
*pos
)
2766 struct swap_info_struct
*si
= v
;
2769 if (v
== SEQ_START_TOKEN
)
2772 type
= si
->type
+ 1;
2775 for (; (si
= swap_type_to_swap_info(type
)); type
++) {
2776 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
2784 static void swap_stop(struct seq_file
*swap
, void *v
)
2786 mutex_unlock(&swapon_mutex
);
2789 static int swap_show(struct seq_file
*swap
, void *v
)
2791 struct swap_info_struct
*si
= v
;
2794 unsigned int bytes
, inuse
;
2796 if (si
== SEQ_START_TOKEN
) {
2797 seq_puts(swap
,"Filename\t\t\t\tType\t\tSize\t\tUsed\t\tPriority\n");
2801 bytes
= si
->pages
<< (PAGE_SHIFT
- 10);
2802 inuse
= si
->inuse_pages
<< (PAGE_SHIFT
- 10);
2804 file
= si
->swap_file
;
2805 len
= seq_file_path(swap
, file
, " \t\n\\");
2806 seq_printf(swap
, "%*s%s\t%u\t%s%u\t%s%d\n",
2807 len
< 40 ? 40 - len
: 1, " ",
2808 S_ISBLK(file_inode(file
)->i_mode
) ?
2809 "partition" : "file\t",
2810 bytes
, bytes
< 10000000 ? "\t" : "",
2811 inuse
, inuse
< 10000000 ? "\t" : "",
2816 static const struct seq_operations swaps_op
= {
2817 .start
= swap_start
,
2823 static int swaps_open(struct inode
*inode
, struct file
*file
)
2825 struct seq_file
*seq
;
2828 ret
= seq_open(file
, &swaps_op
);
2832 seq
= file
->private_data
;
2833 seq
->poll_event
= atomic_read(&proc_poll_event
);
2837 static const struct proc_ops swaps_proc_ops
= {
2838 .proc_flags
= PROC_ENTRY_PERMANENT
,
2839 .proc_open
= swaps_open
,
2840 .proc_read
= seq_read
,
2841 .proc_lseek
= seq_lseek
,
2842 .proc_release
= seq_release
,
2843 .proc_poll
= swaps_poll
,
2846 static int __init
procswaps_init(void)
2848 proc_create("swaps", 0, NULL
, &swaps_proc_ops
);
2851 __initcall(procswaps_init
);
2852 #endif /* CONFIG_PROC_FS */
2854 #ifdef MAX_SWAPFILES_CHECK
2855 static int __init
max_swapfiles_check(void)
2857 MAX_SWAPFILES_CHECK();
2860 late_initcall(max_swapfiles_check
);
2863 static struct swap_info_struct
*alloc_swap_info(void)
2865 struct swap_info_struct
*p
;
2869 p
= kvzalloc(struct_size(p
, avail_lists
, nr_node_ids
), GFP_KERNEL
);
2871 return ERR_PTR(-ENOMEM
);
2873 spin_lock(&swap_lock
);
2874 for (type
= 0; type
< nr_swapfiles
; type
++) {
2875 if (!(swap_info
[type
]->flags
& SWP_USED
))
2878 if (type
>= MAX_SWAPFILES
) {
2879 spin_unlock(&swap_lock
);
2881 return ERR_PTR(-EPERM
);
2883 if (type
>= nr_swapfiles
) {
2885 WRITE_ONCE(swap_info
[type
], p
);
2887 * Write swap_info[type] before nr_swapfiles, in case a
2888 * racing procfs swap_start() or swap_next() is reading them.
2889 * (We never shrink nr_swapfiles, we never free this entry.)
2892 WRITE_ONCE(nr_swapfiles
, nr_swapfiles
+ 1);
2895 p
= swap_info
[type
];
2897 * Do not memset this entry: a racing procfs swap_next()
2898 * would be relying on p->type to remain valid.
2901 p
->swap_extent_root
= RB_ROOT
;
2902 plist_node_init(&p
->list
, 0);
2904 plist_node_init(&p
->avail_lists
[i
], 0);
2905 p
->flags
= SWP_USED
;
2906 spin_unlock(&swap_lock
);
2907 spin_lock_init(&p
->lock
);
2908 spin_lock_init(&p
->cont_lock
);
2913 static int claim_swapfile(struct swap_info_struct
*p
, struct inode
*inode
)
2917 if (S_ISBLK(inode
->i_mode
)) {
2918 p
->bdev
= bdgrab(I_BDEV(inode
));
2919 error
= blkdev_get(p
->bdev
,
2920 FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
, p
);
2925 p
->old_block_size
= block_size(p
->bdev
);
2926 error
= set_blocksize(p
->bdev
, PAGE_SIZE
);
2930 * Zoned block devices contain zones that have a sequential
2931 * write only restriction. Hence zoned block devices are not
2932 * suitable for swapping. Disallow them here.
2934 if (blk_queue_is_zoned(p
->bdev
->bd_disk
->queue
))
2936 p
->flags
|= SWP_BLKDEV
;
2937 } else if (S_ISREG(inode
->i_mode
)) {
2938 p
->bdev
= inode
->i_sb
->s_bdev
;
2946 * Find out how many pages are allowed for a single swap device. There
2947 * are two limiting factors:
2948 * 1) the number of bits for the swap offset in the swp_entry_t type, and
2949 * 2) the number of bits in the swap pte, as defined by the different
2952 * In order to find the largest possible bit mask, a swap entry with
2953 * swap type 0 and swap offset ~0UL is created, encoded to a swap pte,
2954 * decoded to a swp_entry_t again, and finally the swap offset is
2957 * This will mask all the bits from the initial ~0UL mask that can't
2958 * be encoded in either the swp_entry_t or the architecture definition
2961 unsigned long generic_max_swapfile_size(void)
2963 return swp_offset(pte_to_swp_entry(
2964 swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
2967 /* Can be overridden by an architecture for additional checks. */
2968 __weak
unsigned long max_swapfile_size(void)
2970 return generic_max_swapfile_size();
2973 static unsigned long read_swap_header(struct swap_info_struct
*p
,
2974 union swap_header
*swap_header
,
2975 struct inode
*inode
)
2978 unsigned long maxpages
;
2979 unsigned long swapfilepages
;
2980 unsigned long last_page
;
2982 if (memcmp("SWAPSPACE2", swap_header
->magic
.magic
, 10)) {
2983 pr_err("Unable to find swap-space signature\n");
2987 /* swap partition endianess hack... */
2988 if (swab32(swap_header
->info
.version
) == 1) {
2989 swab32s(&swap_header
->info
.version
);
2990 swab32s(&swap_header
->info
.last_page
);
2991 swab32s(&swap_header
->info
.nr_badpages
);
2992 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
2994 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++)
2995 swab32s(&swap_header
->info
.badpages
[i
]);
2997 /* Check the swap header's sub-version */
2998 if (swap_header
->info
.version
!= 1) {
2999 pr_warn("Unable to handle swap header version %d\n",
3000 swap_header
->info
.version
);
3005 p
->cluster_next
= 1;
3008 maxpages
= max_swapfile_size();
3009 last_page
= swap_header
->info
.last_page
;
3011 pr_warn("Empty swap-file\n");
3014 if (last_page
> maxpages
) {
3015 pr_warn("Truncating oversized swap area, only using %luk out of %luk\n",
3016 maxpages
<< (PAGE_SHIFT
- 10),
3017 last_page
<< (PAGE_SHIFT
- 10));
3019 if (maxpages
> last_page
) {
3020 maxpages
= last_page
+ 1;
3021 /* p->max is an unsigned int: don't overflow it */
3022 if ((unsigned int)maxpages
== 0)
3023 maxpages
= UINT_MAX
;
3025 p
->highest_bit
= maxpages
- 1;
3029 swapfilepages
= i_size_read(inode
) >> PAGE_SHIFT
;
3030 if (swapfilepages
&& maxpages
> swapfilepages
) {
3031 pr_warn("Swap area shorter than signature indicates\n");
3034 if (swap_header
->info
.nr_badpages
&& S_ISREG(inode
->i_mode
))
3036 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
3042 #define SWAP_CLUSTER_INFO_COLS \
3043 DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
3044 #define SWAP_CLUSTER_SPACE_COLS \
3045 DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
3046 #define SWAP_CLUSTER_COLS \
3047 max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
3049 static int setup_swap_map_and_extents(struct swap_info_struct
*p
,
3050 union swap_header
*swap_header
,
3051 unsigned char *swap_map
,
3052 struct swap_cluster_info
*cluster_info
,
3053 unsigned long maxpages
,
3057 unsigned int nr_good_pages
;
3059 unsigned long nr_clusters
= DIV_ROUND_UP(maxpages
, SWAPFILE_CLUSTER
);
3060 unsigned long col
= p
->cluster_next
/ SWAPFILE_CLUSTER
% SWAP_CLUSTER_COLS
;
3061 unsigned long i
, idx
;
3063 nr_good_pages
= maxpages
- 1; /* omit header page */
3065 cluster_list_init(&p
->free_clusters
);
3066 cluster_list_init(&p
->discard_clusters
);
3068 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++) {
3069 unsigned int page_nr
= swap_header
->info
.badpages
[i
];
3070 if (page_nr
== 0 || page_nr
> swap_header
->info
.last_page
)
3072 if (page_nr
< maxpages
) {
3073 swap_map
[page_nr
] = SWAP_MAP_BAD
;
3076 * Haven't marked the cluster free yet, no list
3077 * operation involved
3079 inc_cluster_info_page(p
, cluster_info
, page_nr
);
3083 /* Haven't marked the cluster free yet, no list operation involved */
3084 for (i
= maxpages
; i
< round_up(maxpages
, SWAPFILE_CLUSTER
); i
++)
3085 inc_cluster_info_page(p
, cluster_info
, i
);
3087 if (nr_good_pages
) {
3088 swap_map
[0] = SWAP_MAP_BAD
;
3090 * Not mark the cluster free yet, no list
3091 * operation involved
3093 inc_cluster_info_page(p
, cluster_info
, 0);
3095 p
->pages
= nr_good_pages
;
3096 nr_extents
= setup_swap_extents(p
, span
);
3099 nr_good_pages
= p
->pages
;
3101 if (!nr_good_pages
) {
3102 pr_warn("Empty swap-file\n");
3111 * Reduce false cache line sharing between cluster_info and
3112 * sharing same address space.
3114 for (k
= 0; k
< SWAP_CLUSTER_COLS
; k
++) {
3115 j
= (k
+ col
) % SWAP_CLUSTER_COLS
;
3116 for (i
= 0; i
< DIV_ROUND_UP(nr_clusters
, SWAP_CLUSTER_COLS
); i
++) {
3117 idx
= i
* SWAP_CLUSTER_COLS
+ j
;
3118 if (idx
>= nr_clusters
)
3120 if (cluster_count(&cluster_info
[idx
]))
3122 cluster_set_flag(&cluster_info
[idx
], CLUSTER_FLAG_FREE
);
3123 cluster_list_add_tail(&p
->free_clusters
, cluster_info
,
3131 * Helper to sys_swapon determining if a given swap
3132 * backing device queue supports DISCARD operations.
3134 static bool swap_discardable(struct swap_info_struct
*si
)
3136 struct request_queue
*q
= bdev_get_queue(si
->bdev
);
3138 if (!q
|| !blk_queue_discard(q
))
3144 SYSCALL_DEFINE2(swapon
, const char __user
*, specialfile
, int, swap_flags
)
3146 struct swap_info_struct
*p
;
3147 struct filename
*name
;
3148 struct file
*swap_file
= NULL
;
3149 struct address_space
*mapping
;
3152 union swap_header
*swap_header
;
3155 unsigned long maxpages
;
3156 unsigned char *swap_map
= NULL
;
3157 struct swap_cluster_info
*cluster_info
= NULL
;
3158 unsigned long *frontswap_map
= NULL
;
3159 struct page
*page
= NULL
;
3160 struct inode
*inode
= NULL
;
3161 bool inced_nr_rotate_swap
= false;
3163 if (swap_flags
& ~SWAP_FLAGS_VALID
)
3166 if (!capable(CAP_SYS_ADMIN
))
3169 if (!swap_avail_heads
)
3172 p
= alloc_swap_info();
3176 INIT_WORK(&p
->discard_work
, swap_discard_work
);
3178 name
= getname(specialfile
);
3180 error
= PTR_ERR(name
);
3184 swap_file
= file_open_name(name
, O_RDWR
|O_LARGEFILE
, 0);
3185 if (IS_ERR(swap_file
)) {
3186 error
= PTR_ERR(swap_file
);
3191 p
->swap_file
= swap_file
;
3192 mapping
= swap_file
->f_mapping
;
3193 inode
= mapping
->host
;
3195 error
= claim_swapfile(p
, inode
);
3196 if (unlikely(error
))
3200 if (IS_SWAPFILE(inode
)) {
3202 goto bad_swap_unlock_inode
;
3206 * Read the swap header.
3208 if (!mapping
->a_ops
->readpage
) {
3210 goto bad_swap_unlock_inode
;
3212 page
= read_mapping_page(mapping
, 0, swap_file
);
3214 error
= PTR_ERR(page
);
3215 goto bad_swap_unlock_inode
;
3217 swap_header
= kmap(page
);
3219 maxpages
= read_swap_header(p
, swap_header
, inode
);
3220 if (unlikely(!maxpages
)) {
3222 goto bad_swap_unlock_inode
;
3225 /* OK, set up the swap map and apply the bad block list */
3226 swap_map
= vzalloc(maxpages
);
3229 goto bad_swap_unlock_inode
;
3232 if (bdi_cap_stable_pages_required(inode_to_bdi(inode
)))
3233 p
->flags
|= SWP_STABLE_WRITES
;
3235 if (bdi_cap_synchronous_io(inode_to_bdi(inode
)))
3236 p
->flags
|= SWP_SYNCHRONOUS_IO
;
3238 if (p
->bdev
&& blk_queue_nonrot(bdev_get_queue(p
->bdev
))) {
3240 unsigned long ci
, nr_cluster
;
3242 p
->flags
|= SWP_SOLIDSTATE
;
3243 p
->cluster_next_cpu
= alloc_percpu(unsigned int);
3244 if (!p
->cluster_next_cpu
) {
3246 goto bad_swap_unlock_inode
;
3249 * select a random position to start with to help wear leveling
3252 for_each_possible_cpu(cpu
) {
3253 per_cpu(*p
->cluster_next_cpu
, cpu
) =
3254 1 + prandom_u32_max(p
->highest_bit
);
3256 nr_cluster
= DIV_ROUND_UP(maxpages
, SWAPFILE_CLUSTER
);
3258 cluster_info
= kvcalloc(nr_cluster
, sizeof(*cluster_info
),
3260 if (!cluster_info
) {
3262 goto bad_swap_unlock_inode
;
3265 for (ci
= 0; ci
< nr_cluster
; ci
++)
3266 spin_lock_init(&((cluster_info
+ ci
)->lock
));
3268 p
->percpu_cluster
= alloc_percpu(struct percpu_cluster
);
3269 if (!p
->percpu_cluster
) {
3271 goto bad_swap_unlock_inode
;
3273 for_each_possible_cpu(cpu
) {
3274 struct percpu_cluster
*cluster
;
3275 cluster
= per_cpu_ptr(p
->percpu_cluster
, cpu
);
3276 cluster_set_null(&cluster
->index
);
3279 atomic_inc(&nr_rotate_swap
);
3280 inced_nr_rotate_swap
= true;
3283 error
= swap_cgroup_swapon(p
->type
, maxpages
);
3285 goto bad_swap_unlock_inode
;
3287 nr_extents
= setup_swap_map_and_extents(p
, swap_header
, swap_map
,
3288 cluster_info
, maxpages
, &span
);
3289 if (unlikely(nr_extents
< 0)) {
3291 goto bad_swap_unlock_inode
;
3293 /* frontswap enabled? set up bit-per-page map for frontswap */
3294 if (IS_ENABLED(CONFIG_FRONTSWAP
))
3295 frontswap_map
= kvcalloc(BITS_TO_LONGS(maxpages
),
3299 if (p
->bdev
&&(swap_flags
& SWAP_FLAG_DISCARD
) && swap_discardable(p
)) {
3301 * When discard is enabled for swap with no particular
3302 * policy flagged, we set all swap discard flags here in
3303 * order to sustain backward compatibility with older
3304 * swapon(8) releases.
3306 p
->flags
|= (SWP_DISCARDABLE
| SWP_AREA_DISCARD
|
3310 * By flagging sys_swapon, a sysadmin can tell us to
3311 * either do single-time area discards only, or to just
3312 * perform discards for released swap page-clusters.
3313 * Now it's time to adjust the p->flags accordingly.
3315 if (swap_flags
& SWAP_FLAG_DISCARD_ONCE
)
3316 p
->flags
&= ~SWP_PAGE_DISCARD
;
3317 else if (swap_flags
& SWAP_FLAG_DISCARD_PAGES
)
3318 p
->flags
&= ~SWP_AREA_DISCARD
;
3320 /* issue a swapon-time discard if it's still required */
3321 if (p
->flags
& SWP_AREA_DISCARD
) {
3322 int err
= discard_swap(p
);
3324 pr_err("swapon: discard_swap(%p): %d\n",
3329 error
= init_swap_address_space(p
->type
, maxpages
);
3331 goto bad_swap_unlock_inode
;
3334 * Flush any pending IO and dirty mappings before we start using this
3337 inode
->i_flags
|= S_SWAPFILE
;
3338 error
= inode_drain_writes(inode
);
3340 inode
->i_flags
&= ~S_SWAPFILE
;
3341 goto bad_swap_unlock_inode
;
3344 mutex_lock(&swapon_mutex
);
3346 if (swap_flags
& SWAP_FLAG_PREFER
)
3348 (swap_flags
& SWAP_FLAG_PRIO_MASK
) >> SWAP_FLAG_PRIO_SHIFT
;
3349 enable_swap_info(p
, prio
, swap_map
, cluster_info
, frontswap_map
);
3351 pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
3352 p
->pages
<<(PAGE_SHIFT
-10), name
->name
, p
->prio
,
3353 nr_extents
, (unsigned long long)span
<<(PAGE_SHIFT
-10),
3354 (p
->flags
& SWP_SOLIDSTATE
) ? "SS" : "",
3355 (p
->flags
& SWP_DISCARDABLE
) ? "D" : "",
3356 (p
->flags
& SWP_AREA_DISCARD
) ? "s" : "",
3357 (p
->flags
& SWP_PAGE_DISCARD
) ? "c" : "",
3358 (frontswap_map
) ? "FS" : "");
3360 mutex_unlock(&swapon_mutex
);
3361 atomic_inc(&proc_poll_event
);
3362 wake_up_interruptible(&proc_poll_wait
);
3366 bad_swap_unlock_inode
:
3367 inode_unlock(inode
);
3369 free_percpu(p
->percpu_cluster
);
3370 p
->percpu_cluster
= NULL
;
3371 free_percpu(p
->cluster_next_cpu
);
3372 p
->cluster_next_cpu
= NULL
;
3373 if (inode
&& S_ISBLK(inode
->i_mode
) && p
->bdev
) {
3374 set_blocksize(p
->bdev
, p
->old_block_size
);
3375 blkdev_put(p
->bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
3378 destroy_swap_extents(p
);
3379 swap_cgroup_swapoff(p
->type
);
3380 spin_lock(&swap_lock
);
3381 p
->swap_file
= NULL
;
3383 spin_unlock(&swap_lock
);
3385 kvfree(cluster_info
);
3386 kvfree(frontswap_map
);
3387 if (inced_nr_rotate_swap
)
3388 atomic_dec(&nr_rotate_swap
);
3390 filp_close(swap_file
, NULL
);
3392 if (page
&& !IS_ERR(page
)) {
3399 inode_unlock(inode
);
3401 enable_swap_slots_cache();
3405 void si_swapinfo(struct sysinfo
*val
)
3408 unsigned long nr_to_be_unused
= 0;
3410 spin_lock(&swap_lock
);
3411 for (type
= 0; type
< nr_swapfiles
; type
++) {
3412 struct swap_info_struct
*si
= swap_info
[type
];
3414 if ((si
->flags
& SWP_USED
) && !(si
->flags
& SWP_WRITEOK
))
3415 nr_to_be_unused
+= si
->inuse_pages
;
3417 val
->freeswap
= atomic_long_read(&nr_swap_pages
) + nr_to_be_unused
;
3418 val
->totalswap
= total_swap_pages
+ nr_to_be_unused
;
3419 spin_unlock(&swap_lock
);
3423 * Verify that a swap entry is valid and increment its swap map count.
3425 * Returns error code in following case.
3427 * - swp_entry is invalid -> EINVAL
3428 * - swp_entry is migration entry -> EINVAL
3429 * - swap-cache reference is requested but there is already one. -> EEXIST
3430 * - swap-cache reference is requested but the entry is not used. -> ENOENT
3431 * - swap-mapped reference requested but needs continued swap count. -> ENOMEM
3433 static int __swap_duplicate(swp_entry_t entry
, unsigned char usage
)
3435 struct swap_info_struct
*p
;
3436 struct swap_cluster_info
*ci
;
3437 unsigned long offset
;
3438 unsigned char count
;
3439 unsigned char has_cache
;
3442 p
= get_swap_device(entry
);
3446 offset
= swp_offset(entry
);
3447 ci
= lock_cluster_or_swap_info(p
, offset
);
3449 count
= p
->swap_map
[offset
];
3452 * swapin_readahead() doesn't check if a swap entry is valid, so the
3453 * swap entry could be SWAP_MAP_BAD. Check here with lock held.
3455 if (unlikely(swap_count(count
) == SWAP_MAP_BAD
)) {
3460 has_cache
= count
& SWAP_HAS_CACHE
;
3461 count
&= ~SWAP_HAS_CACHE
;
3464 if (usage
== SWAP_HAS_CACHE
) {
3466 /* set SWAP_HAS_CACHE if there is no cache and entry is used */
3467 if (!has_cache
&& count
)
3468 has_cache
= SWAP_HAS_CACHE
;
3469 else if (has_cache
) /* someone else added cache */
3471 else /* no users remaining */
3474 } else if (count
|| has_cache
) {
3476 if ((count
& ~COUNT_CONTINUED
) < SWAP_MAP_MAX
)
3478 else if ((count
& ~COUNT_CONTINUED
) > SWAP_MAP_MAX
)
3480 else if (swap_count_continued(p
, offset
, count
))
3481 count
= COUNT_CONTINUED
;
3485 err
= -ENOENT
; /* unused swap entry */
3487 p
->swap_map
[offset
] = count
| has_cache
;
3490 unlock_cluster_or_swap_info(p
, ci
);
3498 * Help swapoff by noting that swap entry belongs to shmem/tmpfs
3499 * (in which case its reference count is never incremented).
3501 void swap_shmem_alloc(swp_entry_t entry
)
3503 __swap_duplicate(entry
, SWAP_MAP_SHMEM
);
3507 * Increase reference count of swap entry by 1.
3508 * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
3509 * but could not be atomically allocated. Returns 0, just as if it succeeded,
3510 * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
3511 * might occur if a page table entry has got corrupted.
3513 int swap_duplicate(swp_entry_t entry
)
3517 while (!err
&& __swap_duplicate(entry
, 1) == -ENOMEM
)
3518 err
= add_swap_count_continuation(entry
, GFP_ATOMIC
);
3523 * @entry: swap entry for which we allocate swap cache.
3525 * Called when allocating swap cache for existing swap entry,
3526 * This can return error codes. Returns 0 at success.
3527 * -EEXIST means there is a swap cache.
3528 * Note: return code is different from swap_duplicate().
3530 int swapcache_prepare(swp_entry_t entry
)
3532 return __swap_duplicate(entry
, SWAP_HAS_CACHE
);
3535 struct swap_info_struct
*swp_swap_info(swp_entry_t entry
)
3537 return swap_type_to_swap_info(swp_type(entry
));
3540 struct swap_info_struct
*page_swap_info(struct page
*page
)
3542 swp_entry_t entry
= { .val
= page_private(page
) };
3543 return swp_swap_info(entry
);
3547 * out-of-line __page_file_ methods to avoid include hell.
3549 struct address_space
*__page_file_mapping(struct page
*page
)
3551 return page_swap_info(page
)->swap_file
->f_mapping
;
3553 EXPORT_SYMBOL_GPL(__page_file_mapping
);
3555 pgoff_t
__page_file_index(struct page
*page
)
3557 swp_entry_t swap
= { .val
= page_private(page
) };
3558 return swp_offset(swap
);
3560 EXPORT_SYMBOL_GPL(__page_file_index
);
3563 * add_swap_count_continuation - called when a swap count is duplicated
3564 * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
3565 * page of the original vmalloc'ed swap_map, to hold the continuation count
3566 * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called
3567 * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
3569 * These continuation pages are seldom referenced: the common paths all work
3570 * on the original swap_map, only referring to a continuation page when the
3571 * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
3573 * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
3574 * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
3575 * can be called after dropping locks.
3577 int add_swap_count_continuation(swp_entry_t entry
, gfp_t gfp_mask
)
3579 struct swap_info_struct
*si
;
3580 struct swap_cluster_info
*ci
;
3583 struct page
*list_page
;
3585 unsigned char count
;
3589 * When debugging, it's easier to use __GFP_ZERO here; but it's better
3590 * for latency not to zero a page while GFP_ATOMIC and holding locks.
3592 page
= alloc_page(gfp_mask
| __GFP_HIGHMEM
);
3594 si
= get_swap_device(entry
);
3597 * An acceptable race has occurred since the failing
3598 * __swap_duplicate(): the swap device may be swapoff
3602 spin_lock(&si
->lock
);
3604 offset
= swp_offset(entry
);
3606 ci
= lock_cluster(si
, offset
);
3608 count
= si
->swap_map
[offset
] & ~SWAP_HAS_CACHE
;
3610 if ((count
& ~COUNT_CONTINUED
) != SWAP_MAP_MAX
) {
3612 * The higher the swap count, the more likely it is that tasks
3613 * will race to add swap count continuation: we need to avoid
3614 * over-provisioning.
3625 * We are fortunate that although vmalloc_to_page uses pte_offset_map,
3626 * no architecture is using highmem pages for kernel page tables: so it
3627 * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps.
3629 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3630 offset
&= ~PAGE_MASK
;
3632 spin_lock(&si
->cont_lock
);
3634 * Page allocation does not initialize the page's lru field,
3635 * but it does always reset its private field.
3637 if (!page_private(head
)) {
3638 BUG_ON(count
& COUNT_CONTINUED
);
3639 INIT_LIST_HEAD(&head
->lru
);
3640 set_page_private(head
, SWP_CONTINUED
);
3641 si
->flags
|= SWP_CONTINUED
;
3644 list_for_each_entry(list_page
, &head
->lru
, lru
) {
3648 * If the previous map said no continuation, but we've found
3649 * a continuation page, free our allocation and use this one.
3651 if (!(count
& COUNT_CONTINUED
))
3652 goto out_unlock_cont
;
3654 map
= kmap_atomic(list_page
) + offset
;
3659 * If this continuation count now has some space in it,
3660 * free our allocation and use this one.
3662 if ((count
& ~COUNT_CONTINUED
) != SWAP_CONT_MAX
)
3663 goto out_unlock_cont
;
3666 list_add_tail(&page
->lru
, &head
->lru
);
3667 page
= NULL
; /* now it's attached, don't free it */
3669 spin_unlock(&si
->cont_lock
);
3672 spin_unlock(&si
->lock
);
3673 put_swap_device(si
);
3681 * swap_count_continued - when the original swap_map count is incremented
3682 * from SWAP_MAP_MAX, check if there is already a continuation page to carry
3683 * into, carry if so, or else fail until a new continuation page is allocated;
3684 * when the original swap_map count is decremented from 0 with continuation,
3685 * borrow from the continuation and report whether it still holds more.
3686 * Called while __swap_duplicate() or swap_entry_free() holds swap or cluster
3689 static bool swap_count_continued(struct swap_info_struct
*si
,
3690 pgoff_t offset
, unsigned char count
)
3697 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3698 if (page_private(head
) != SWP_CONTINUED
) {
3699 BUG_ON(count
& COUNT_CONTINUED
);
3700 return false; /* need to add count continuation */
3703 spin_lock(&si
->cont_lock
);
3704 offset
&= ~PAGE_MASK
;
3705 page
= list_next_entry(head
, lru
);
3706 map
= kmap_atomic(page
) + offset
;
3708 if (count
== SWAP_MAP_MAX
) /* initial increment from swap_map */
3709 goto init_map
; /* jump over SWAP_CONT_MAX checks */
3711 if (count
== (SWAP_MAP_MAX
| COUNT_CONTINUED
)) { /* incrementing */
3713 * Think of how you add 1 to 999
3715 while (*map
== (SWAP_CONT_MAX
| COUNT_CONTINUED
)) {
3717 page
= list_next_entry(page
, lru
);
3718 BUG_ON(page
== head
);
3719 map
= kmap_atomic(page
) + offset
;
3721 if (*map
== SWAP_CONT_MAX
) {
3723 page
= list_next_entry(page
, lru
);
3725 ret
= false; /* add count continuation */
3728 map
= kmap_atomic(page
) + offset
;
3729 init_map
: *map
= 0; /* we didn't zero the page */
3733 while ((page
= list_prev_entry(page
, lru
)) != head
) {
3734 map
= kmap_atomic(page
) + offset
;
3735 *map
= COUNT_CONTINUED
;
3738 ret
= true; /* incremented */
3740 } else { /* decrementing */
3742 * Think of how you subtract 1 from 1000
3744 BUG_ON(count
!= COUNT_CONTINUED
);
3745 while (*map
== COUNT_CONTINUED
) {
3747 page
= list_next_entry(page
, lru
);
3748 BUG_ON(page
== head
);
3749 map
= kmap_atomic(page
) + offset
;
3756 while ((page
= list_prev_entry(page
, lru
)) != head
) {
3757 map
= kmap_atomic(page
) + offset
;
3758 *map
= SWAP_CONT_MAX
| count
;
3759 count
= COUNT_CONTINUED
;
3762 ret
= count
== COUNT_CONTINUED
;
3765 spin_unlock(&si
->cont_lock
);
3770 * free_swap_count_continuations - swapoff free all the continuation pages
3771 * appended to the swap_map, after swap_map is quiesced, before vfree'ing it.
3773 static void free_swap_count_continuations(struct swap_info_struct
*si
)
3777 for (offset
= 0; offset
< si
->max
; offset
+= PAGE_SIZE
) {
3779 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3780 if (page_private(head
)) {
3781 struct page
*page
, *next
;
3783 list_for_each_entry_safe(page
, next
, &head
->lru
, lru
) {
3784 list_del(&page
->lru
);
3791 #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
3792 void cgroup_throttle_swaprate(struct page
*page
, gfp_t gfp_mask
)
3794 struct swap_info_struct
*si
, *next
;
3795 int nid
= page_to_nid(page
);
3797 if (!(gfp_mask
& __GFP_IO
))
3800 if (!blk_cgroup_congested())
3804 * We've already scheduled a throttle, avoid taking the global swap
3807 if (current
->throttle_queue
)
3810 spin_lock(&swap_avail_lock
);
3811 plist_for_each_entry_safe(si
, next
, &swap_avail_heads
[nid
],
3814 blkcg_schedule_throttle(bdev_get_queue(si
->bdev
), true);
3818 spin_unlock(&swap_avail_lock
);
3822 static int __init
swapfile_init(void)
3826 swap_avail_heads
= kmalloc_array(nr_node_ids
, sizeof(struct plist_head
),
3828 if (!swap_avail_heads
) {
3829 pr_emerg("Not enough memory for swap heads, swap is disabled\n");
3834 plist_head_init(&swap_avail_heads
[nid
]);
3838 subsys_initcall(swapfile_init
);