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
*);
51 DEFINE_SPINLOCK(swap_lock
);
52 static unsigned int nr_swapfiles
;
53 atomic_long_t nr_swap_pages
;
55 * Some modules use swappable objects and may try to swap them out under
56 * memory pressure (via the shrinker). Before doing so, they may wish to
57 * check to see if any swap space is available.
59 EXPORT_SYMBOL_GPL(nr_swap_pages
);
60 /* protected with swap_lock. reading in vm_swap_full() doesn't need lock */
61 long total_swap_pages
;
62 static int least_priority
= -1;
64 static const char Bad_file
[] = "Bad swap file entry ";
65 static const char Unused_file
[] = "Unused swap file entry ";
66 static const char Bad_offset
[] = "Bad swap offset entry ";
67 static const char Unused_offset
[] = "Unused swap offset entry ";
70 * all active swap_info_structs
71 * protected with swap_lock, and ordered by priority.
73 PLIST_HEAD(swap_active_head
);
76 * all available (active, not full) swap_info_structs
77 * protected with swap_avail_lock, ordered by priority.
78 * This is used by get_swap_page() instead of swap_active_head
79 * because swap_active_head includes all swap_info_structs,
80 * but get_swap_page() doesn't need to look at full ones.
81 * This uses its own lock instead of swap_lock because when a
82 * swap_info_struct changes between not-full/full, it needs to
83 * add/remove itself to/from this list, but the swap_info_struct->lock
84 * is held and the locking order requires swap_lock to be taken
85 * before any swap_info_struct->lock.
87 static struct plist_head
*swap_avail_heads
;
88 static DEFINE_SPINLOCK(swap_avail_lock
);
90 struct swap_info_struct
*swap_info
[MAX_SWAPFILES
];
92 static DEFINE_MUTEX(swapon_mutex
);
94 static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait
);
95 /* Activity counter to indicate that a swapon or swapoff has occurred */
96 static atomic_t proc_poll_event
= ATOMIC_INIT(0);
98 atomic_t nr_rotate_swap
= ATOMIC_INIT(0);
100 static struct swap_info_struct
*swap_type_to_swap_info(int type
)
102 if (type
>= READ_ONCE(nr_swapfiles
))
105 smp_rmb(); /* Pairs with smp_wmb in alloc_swap_info. */
106 return READ_ONCE(swap_info
[type
]);
109 static inline unsigned char swap_count(unsigned char ent
)
111 return ent
& ~SWAP_HAS_CACHE
; /* may include COUNT_CONTINUED flag */
114 /* Reclaim the swap entry anyway if possible */
115 #define TTRS_ANYWAY 0x1
117 * Reclaim the swap entry if there are no more mappings of the
120 #define TTRS_UNMAPPED 0x2
121 /* Reclaim the swap entry if swap is getting full*/
122 #define TTRS_FULL 0x4
124 /* returns 1 if swap entry is freed */
125 static int __try_to_reclaim_swap(struct swap_info_struct
*si
,
126 unsigned long offset
, unsigned long flags
)
128 swp_entry_t entry
= swp_entry(si
->type
, offset
);
132 page
= find_get_page(swap_address_space(entry
), offset
);
136 * When this function is called from scan_swap_map_slots() and it's
137 * called by vmscan.c at reclaiming pages. So, we hold a lock on a page,
138 * here. We have to use trylock for avoiding deadlock. This is a special
139 * case and you should use try_to_free_swap() with explicit lock_page()
140 * in usual operations.
142 if (trylock_page(page
)) {
143 if ((flags
& TTRS_ANYWAY
) ||
144 ((flags
& TTRS_UNMAPPED
) && !page_mapped(page
)) ||
145 ((flags
& TTRS_FULL
) && mem_cgroup_swap_full(page
)))
146 ret
= try_to_free_swap(page
);
153 static inline struct swap_extent
*first_se(struct swap_info_struct
*sis
)
155 struct rb_node
*rb
= rb_first(&sis
->swap_extent_root
);
156 return rb_entry(rb
, struct swap_extent
, rb_node
);
159 static inline struct swap_extent
*next_se(struct swap_extent
*se
)
161 struct rb_node
*rb
= rb_next(&se
->rb_node
);
162 return rb
? rb_entry(rb
, struct swap_extent
, rb_node
) : NULL
;
166 * swapon tell device that all the old swap contents can be discarded,
167 * to allow the swap device to optimize its wear-levelling.
169 static int discard_swap(struct swap_info_struct
*si
)
171 struct swap_extent
*se
;
172 sector_t start_block
;
176 /* Do not discard the swap header page! */
178 start_block
= (se
->start_block
+ 1) << (PAGE_SHIFT
- 9);
179 nr_blocks
= ((sector_t
)se
->nr_pages
- 1) << (PAGE_SHIFT
- 9);
181 err
= blkdev_issue_discard(si
->bdev
, start_block
,
182 nr_blocks
, GFP_KERNEL
, 0);
188 for (se
= next_se(se
); se
; se
= next_se(se
)) {
189 start_block
= se
->start_block
<< (PAGE_SHIFT
- 9);
190 nr_blocks
= (sector_t
)se
->nr_pages
<< (PAGE_SHIFT
- 9);
192 err
= blkdev_issue_discard(si
->bdev
, start_block
,
193 nr_blocks
, GFP_KERNEL
, 0);
199 return err
; /* That will often be -EOPNOTSUPP */
202 static struct swap_extent
*
203 offset_to_swap_extent(struct swap_info_struct
*sis
, unsigned long offset
)
205 struct swap_extent
*se
;
208 rb
= sis
->swap_extent_root
.rb_node
;
210 se
= rb_entry(rb
, struct swap_extent
, rb_node
);
211 if (offset
< se
->start_page
)
213 else if (offset
>= se
->start_page
+ se
->nr_pages
)
218 /* It *must* be present */
223 * swap allocation tell device that a cluster of swap can now be discarded,
224 * to allow the swap device to optimize its wear-levelling.
226 static void discard_swap_cluster(struct swap_info_struct
*si
,
227 pgoff_t start_page
, pgoff_t nr_pages
)
229 struct swap_extent
*se
= offset_to_swap_extent(si
, start_page
);
232 pgoff_t offset
= start_page
- se
->start_page
;
233 sector_t start_block
= se
->start_block
+ offset
;
234 sector_t nr_blocks
= se
->nr_pages
- offset
;
236 if (nr_blocks
> nr_pages
)
237 nr_blocks
= nr_pages
;
238 start_page
+= nr_blocks
;
239 nr_pages
-= nr_blocks
;
241 start_block
<<= PAGE_SHIFT
- 9;
242 nr_blocks
<<= PAGE_SHIFT
- 9;
243 if (blkdev_issue_discard(si
->bdev
, start_block
,
244 nr_blocks
, GFP_NOIO
, 0))
251 #ifdef CONFIG_THP_SWAP
252 #define SWAPFILE_CLUSTER HPAGE_PMD_NR
254 #define swap_entry_size(size) (size)
256 #define SWAPFILE_CLUSTER 256
259 * Define swap_entry_size() as constant to let compiler to optimize
260 * out some code if !CONFIG_THP_SWAP
262 #define swap_entry_size(size) 1
264 #define LATENCY_LIMIT 256
266 static inline void cluster_set_flag(struct swap_cluster_info
*info
,
272 static inline unsigned int cluster_count(struct swap_cluster_info
*info
)
277 static inline void cluster_set_count(struct swap_cluster_info
*info
,
283 static inline void cluster_set_count_flag(struct swap_cluster_info
*info
,
284 unsigned int c
, unsigned int f
)
290 static inline unsigned int cluster_next(struct swap_cluster_info
*info
)
295 static inline void cluster_set_next(struct swap_cluster_info
*info
,
301 static inline void cluster_set_next_flag(struct swap_cluster_info
*info
,
302 unsigned int n
, unsigned int f
)
308 static inline bool cluster_is_free(struct swap_cluster_info
*info
)
310 return info
->flags
& CLUSTER_FLAG_FREE
;
313 static inline bool cluster_is_null(struct swap_cluster_info
*info
)
315 return info
->flags
& CLUSTER_FLAG_NEXT_NULL
;
318 static inline void cluster_set_null(struct swap_cluster_info
*info
)
320 info
->flags
= CLUSTER_FLAG_NEXT_NULL
;
324 static inline bool cluster_is_huge(struct swap_cluster_info
*info
)
326 if (IS_ENABLED(CONFIG_THP_SWAP
))
327 return info
->flags
& CLUSTER_FLAG_HUGE
;
331 static inline void cluster_clear_huge(struct swap_cluster_info
*info
)
333 info
->flags
&= ~CLUSTER_FLAG_HUGE
;
336 static inline struct swap_cluster_info
*lock_cluster(struct swap_info_struct
*si
,
337 unsigned long offset
)
339 struct swap_cluster_info
*ci
;
341 ci
= si
->cluster_info
;
343 ci
+= offset
/ SWAPFILE_CLUSTER
;
344 spin_lock(&ci
->lock
);
349 static inline void unlock_cluster(struct swap_cluster_info
*ci
)
352 spin_unlock(&ci
->lock
);
356 * Determine the locking method in use for this device. Return
357 * swap_cluster_info if SSD-style cluster-based locking is in place.
359 static inline struct swap_cluster_info
*lock_cluster_or_swap_info(
360 struct swap_info_struct
*si
, unsigned long offset
)
362 struct swap_cluster_info
*ci
;
364 /* Try to use fine-grained SSD-style locking if available: */
365 ci
= lock_cluster(si
, offset
);
366 /* Otherwise, fall back to traditional, coarse locking: */
368 spin_lock(&si
->lock
);
373 static inline void unlock_cluster_or_swap_info(struct swap_info_struct
*si
,
374 struct swap_cluster_info
*ci
)
379 spin_unlock(&si
->lock
);
382 static inline bool cluster_list_empty(struct swap_cluster_list
*list
)
384 return cluster_is_null(&list
->head
);
387 static inline unsigned int cluster_list_first(struct swap_cluster_list
*list
)
389 return cluster_next(&list
->head
);
392 static void cluster_list_init(struct swap_cluster_list
*list
)
394 cluster_set_null(&list
->head
);
395 cluster_set_null(&list
->tail
);
398 static void cluster_list_add_tail(struct swap_cluster_list
*list
,
399 struct swap_cluster_info
*ci
,
402 if (cluster_list_empty(list
)) {
403 cluster_set_next_flag(&list
->head
, idx
, 0);
404 cluster_set_next_flag(&list
->tail
, idx
, 0);
406 struct swap_cluster_info
*ci_tail
;
407 unsigned int tail
= cluster_next(&list
->tail
);
410 * Nested cluster lock, but both cluster locks are
411 * only acquired when we held swap_info_struct->lock
414 spin_lock_nested(&ci_tail
->lock
, SINGLE_DEPTH_NESTING
);
415 cluster_set_next(ci_tail
, idx
);
416 spin_unlock(&ci_tail
->lock
);
417 cluster_set_next_flag(&list
->tail
, idx
, 0);
421 static unsigned int cluster_list_del_first(struct swap_cluster_list
*list
,
422 struct swap_cluster_info
*ci
)
426 idx
= cluster_next(&list
->head
);
427 if (cluster_next(&list
->tail
) == idx
) {
428 cluster_set_null(&list
->head
);
429 cluster_set_null(&list
->tail
);
431 cluster_set_next_flag(&list
->head
,
432 cluster_next(&ci
[idx
]), 0);
437 /* Add a cluster to discard list and schedule it to do discard */
438 static void swap_cluster_schedule_discard(struct swap_info_struct
*si
,
442 * If scan_swap_map() can't find a free cluster, it will check
443 * si->swap_map directly. To make sure the discarding cluster isn't
444 * taken by scan_swap_map(), mark the swap entries bad (occupied). It
445 * will be cleared after discard
447 memset(si
->swap_map
+ idx
* SWAPFILE_CLUSTER
,
448 SWAP_MAP_BAD
, SWAPFILE_CLUSTER
);
450 cluster_list_add_tail(&si
->discard_clusters
, si
->cluster_info
, idx
);
452 schedule_work(&si
->discard_work
);
455 static void __free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
457 struct swap_cluster_info
*ci
= si
->cluster_info
;
459 cluster_set_flag(ci
+ idx
, CLUSTER_FLAG_FREE
);
460 cluster_list_add_tail(&si
->free_clusters
, ci
, idx
);
464 * Doing discard actually. After a cluster discard is finished, the cluster
465 * will be added to free cluster list. caller should hold si->lock.
467 static void swap_do_scheduled_discard(struct swap_info_struct
*si
)
469 struct swap_cluster_info
*info
, *ci
;
472 info
= si
->cluster_info
;
474 while (!cluster_list_empty(&si
->discard_clusters
)) {
475 idx
= cluster_list_del_first(&si
->discard_clusters
, info
);
476 spin_unlock(&si
->lock
);
478 discard_swap_cluster(si
, idx
* SWAPFILE_CLUSTER
,
481 spin_lock(&si
->lock
);
482 ci
= lock_cluster(si
, idx
* SWAPFILE_CLUSTER
);
483 __free_cluster(si
, idx
);
484 memset(si
->swap_map
+ idx
* SWAPFILE_CLUSTER
,
485 0, SWAPFILE_CLUSTER
);
490 static void swap_discard_work(struct work_struct
*work
)
492 struct swap_info_struct
*si
;
494 si
= container_of(work
, struct swap_info_struct
, discard_work
);
496 spin_lock(&si
->lock
);
497 swap_do_scheduled_discard(si
);
498 spin_unlock(&si
->lock
);
501 static void alloc_cluster(struct swap_info_struct
*si
, unsigned long idx
)
503 struct swap_cluster_info
*ci
= si
->cluster_info
;
505 VM_BUG_ON(cluster_list_first(&si
->free_clusters
) != idx
);
506 cluster_list_del_first(&si
->free_clusters
, ci
);
507 cluster_set_count_flag(ci
+ idx
, 0, 0);
510 static void free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
512 struct swap_cluster_info
*ci
= si
->cluster_info
+ idx
;
514 VM_BUG_ON(cluster_count(ci
) != 0);
516 * If the swap is discardable, prepare discard the cluster
517 * instead of free it immediately. The cluster will be freed
520 if ((si
->flags
& (SWP_WRITEOK
| SWP_PAGE_DISCARD
)) ==
521 (SWP_WRITEOK
| SWP_PAGE_DISCARD
)) {
522 swap_cluster_schedule_discard(si
, idx
);
526 __free_cluster(si
, idx
);
530 * The cluster corresponding to page_nr will be used. The cluster will be
531 * removed from free cluster list and its usage counter will be increased.
533 static void inc_cluster_info_page(struct swap_info_struct
*p
,
534 struct swap_cluster_info
*cluster_info
, unsigned long page_nr
)
536 unsigned long idx
= page_nr
/ SWAPFILE_CLUSTER
;
540 if (cluster_is_free(&cluster_info
[idx
]))
541 alloc_cluster(p
, idx
);
543 VM_BUG_ON(cluster_count(&cluster_info
[idx
]) >= SWAPFILE_CLUSTER
);
544 cluster_set_count(&cluster_info
[idx
],
545 cluster_count(&cluster_info
[idx
]) + 1);
549 * The cluster corresponding to page_nr decreases one usage. If the usage
550 * counter becomes 0, which means no page in the cluster is in using, we can
551 * optionally discard the cluster and add it to free cluster list.
553 static void dec_cluster_info_page(struct swap_info_struct
*p
,
554 struct swap_cluster_info
*cluster_info
, unsigned long page_nr
)
556 unsigned long idx
= page_nr
/ SWAPFILE_CLUSTER
;
561 VM_BUG_ON(cluster_count(&cluster_info
[idx
]) == 0);
562 cluster_set_count(&cluster_info
[idx
],
563 cluster_count(&cluster_info
[idx
]) - 1);
565 if (cluster_count(&cluster_info
[idx
]) == 0)
566 free_cluster(p
, idx
);
570 * It's possible scan_swap_map() uses a free cluster in the middle of free
571 * cluster list. Avoiding such abuse to avoid list corruption.
574 scan_swap_map_ssd_cluster_conflict(struct swap_info_struct
*si
,
575 unsigned long offset
)
577 struct percpu_cluster
*percpu_cluster
;
580 offset
/= SWAPFILE_CLUSTER
;
581 conflict
= !cluster_list_empty(&si
->free_clusters
) &&
582 offset
!= cluster_list_first(&si
->free_clusters
) &&
583 cluster_is_free(&si
->cluster_info
[offset
]);
588 percpu_cluster
= this_cpu_ptr(si
->percpu_cluster
);
589 cluster_set_null(&percpu_cluster
->index
);
594 * Try to get a swap entry from current cpu's swap entry pool (a cluster). This
595 * might involve allocating a new cluster for current CPU too.
597 static bool scan_swap_map_try_ssd_cluster(struct swap_info_struct
*si
,
598 unsigned long *offset
, unsigned long *scan_base
)
600 struct percpu_cluster
*cluster
;
601 struct swap_cluster_info
*ci
;
602 unsigned long tmp
, max
;
605 cluster
= this_cpu_ptr(si
->percpu_cluster
);
606 if (cluster_is_null(&cluster
->index
)) {
607 if (!cluster_list_empty(&si
->free_clusters
)) {
608 cluster
->index
= si
->free_clusters
.head
;
609 cluster
->next
= cluster_next(&cluster
->index
) *
611 } else if (!cluster_list_empty(&si
->discard_clusters
)) {
613 * we don't have free cluster but have some clusters in
614 * discarding, do discard now and reclaim them, then
615 * reread cluster_next_cpu since we dropped si->lock
617 swap_do_scheduled_discard(si
);
618 *scan_base
= this_cpu_read(*si
->cluster_next_cpu
);
619 *offset
= *scan_base
;
626 * Other CPUs can use our cluster if they can't find a free cluster,
627 * check if there is still free entry in the cluster
630 max
= min_t(unsigned long, si
->max
,
631 (cluster_next(&cluster
->index
) + 1) * SWAPFILE_CLUSTER
);
633 ci
= lock_cluster(si
, tmp
);
635 if (!si
->swap_map
[tmp
])
642 cluster_set_null(&cluster
->index
);
645 cluster
->next
= tmp
+ 1;
651 static void __del_from_avail_list(struct swap_info_struct
*p
)
656 plist_del(&p
->avail_lists
[nid
], &swap_avail_heads
[nid
]);
659 static void del_from_avail_list(struct swap_info_struct
*p
)
661 spin_lock(&swap_avail_lock
);
662 __del_from_avail_list(p
);
663 spin_unlock(&swap_avail_lock
);
666 static void swap_range_alloc(struct swap_info_struct
*si
, unsigned long offset
,
667 unsigned int nr_entries
)
669 unsigned int end
= offset
+ nr_entries
- 1;
671 if (offset
== si
->lowest_bit
)
672 si
->lowest_bit
+= nr_entries
;
673 if (end
== si
->highest_bit
)
674 WRITE_ONCE(si
->highest_bit
, si
->highest_bit
- nr_entries
);
675 si
->inuse_pages
+= nr_entries
;
676 if (si
->inuse_pages
== si
->pages
) {
677 si
->lowest_bit
= si
->max
;
679 del_from_avail_list(si
);
683 static void add_to_avail_list(struct swap_info_struct
*p
)
687 spin_lock(&swap_avail_lock
);
689 WARN_ON(!plist_node_empty(&p
->avail_lists
[nid
]));
690 plist_add(&p
->avail_lists
[nid
], &swap_avail_heads
[nid
]);
692 spin_unlock(&swap_avail_lock
);
695 static void swap_range_free(struct swap_info_struct
*si
, unsigned long offset
,
696 unsigned int nr_entries
)
698 unsigned long begin
= offset
;
699 unsigned long end
= offset
+ nr_entries
- 1;
700 void (*swap_slot_free_notify
)(struct block_device
*, unsigned long);
702 if (offset
< si
->lowest_bit
)
703 si
->lowest_bit
= offset
;
704 if (end
> si
->highest_bit
) {
705 bool was_full
= !si
->highest_bit
;
707 WRITE_ONCE(si
->highest_bit
, end
);
708 if (was_full
&& (si
->flags
& SWP_WRITEOK
))
709 add_to_avail_list(si
);
711 atomic_long_add(nr_entries
, &nr_swap_pages
);
712 si
->inuse_pages
-= nr_entries
;
713 if (si
->flags
& SWP_BLKDEV
)
714 swap_slot_free_notify
=
715 si
->bdev
->bd_disk
->fops
->swap_slot_free_notify
;
717 swap_slot_free_notify
= NULL
;
718 while (offset
<= end
) {
719 arch_swap_invalidate_page(si
->type
, offset
);
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 WRITE_ONCE(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
<= READ_ONCE(si
->highest_bit
)) {
933 if (data_race(!si
->swap_map
[offset
])) {
934 spin_lock(&si
->lock
);
937 if (vm_swap_full() &&
938 READ_ONCE(si
->swap_map
[offset
]) == SWAP_HAS_CACHE
) {
939 spin_lock(&si
->lock
);
942 if (unlikely(--latency_ration
< 0)) {
944 latency_ration
= LATENCY_LIMIT
;
948 offset
= si
->lowest_bit
;
949 while (offset
< scan_base
) {
950 if (data_race(!si
->swap_map
[offset
])) {
951 spin_lock(&si
->lock
);
954 if (vm_swap_full() &&
955 READ_ONCE(si
->swap_map
[offset
]) == SWAP_HAS_CACHE
) {
956 spin_lock(&si
->lock
);
959 if (unlikely(--latency_ration
< 0)) {
961 latency_ration
= LATENCY_LIMIT
;
966 spin_lock(&si
->lock
);
969 si
->flags
-= SWP_SCANNING
;
973 static int swap_alloc_cluster(struct swap_info_struct
*si
, swp_entry_t
*slot
)
976 struct swap_cluster_info
*ci
;
977 unsigned long offset
;
980 * Should not even be attempting cluster allocations when huge
981 * page swap is disabled. Warn and fail the allocation.
983 if (!IS_ENABLED(CONFIG_THP_SWAP
)) {
988 if (cluster_list_empty(&si
->free_clusters
))
991 idx
= cluster_list_first(&si
->free_clusters
);
992 offset
= idx
* SWAPFILE_CLUSTER
;
993 ci
= lock_cluster(si
, offset
);
994 alloc_cluster(si
, idx
);
995 cluster_set_count_flag(ci
, SWAPFILE_CLUSTER
, CLUSTER_FLAG_HUGE
);
997 memset(si
->swap_map
+ offset
, SWAP_HAS_CACHE
, SWAPFILE_CLUSTER
);
999 swap_range_alloc(si
, offset
, SWAPFILE_CLUSTER
);
1000 *slot
= swp_entry(si
->type
, offset
);
1005 static void swap_free_cluster(struct swap_info_struct
*si
, unsigned long idx
)
1007 unsigned long offset
= idx
* SWAPFILE_CLUSTER
;
1008 struct swap_cluster_info
*ci
;
1010 ci
= lock_cluster(si
, offset
);
1011 memset(si
->swap_map
+ offset
, 0, SWAPFILE_CLUSTER
);
1012 cluster_set_count_flag(ci
, 0, 0);
1013 free_cluster(si
, idx
);
1015 swap_range_free(si
, offset
, SWAPFILE_CLUSTER
);
1018 static unsigned long scan_swap_map(struct swap_info_struct
*si
,
1019 unsigned char usage
)
1024 n_ret
= scan_swap_map_slots(si
, usage
, 1, &entry
);
1027 return swp_offset(entry
);
1033 int get_swap_pages(int n_goal
, swp_entry_t swp_entries
[], int entry_size
)
1035 unsigned long size
= swap_entry_size(entry_size
);
1036 struct swap_info_struct
*si
, *next
;
1041 /* Only single cluster request supported */
1042 WARN_ON_ONCE(n_goal
> 1 && size
== SWAPFILE_CLUSTER
);
1044 spin_lock(&swap_avail_lock
);
1046 avail_pgs
= atomic_long_read(&nr_swap_pages
) / size
;
1047 if (avail_pgs
<= 0) {
1048 spin_unlock(&swap_avail_lock
);
1052 n_goal
= min3((long)n_goal
, (long)SWAP_BATCH
, avail_pgs
);
1054 atomic_long_sub(n_goal
* size
, &nr_swap_pages
);
1057 node
= numa_node_id();
1058 plist_for_each_entry_safe(si
, next
, &swap_avail_heads
[node
], avail_lists
[node
]) {
1059 /* requeue si to after same-priority siblings */
1060 plist_requeue(&si
->avail_lists
[node
], &swap_avail_heads
[node
]);
1061 spin_unlock(&swap_avail_lock
);
1062 spin_lock(&si
->lock
);
1063 if (!si
->highest_bit
|| !(si
->flags
& SWP_WRITEOK
)) {
1064 spin_lock(&swap_avail_lock
);
1065 if (plist_node_empty(&si
->avail_lists
[node
])) {
1066 spin_unlock(&si
->lock
);
1069 WARN(!si
->highest_bit
,
1070 "swap_info %d in list but !highest_bit\n",
1072 WARN(!(si
->flags
& SWP_WRITEOK
),
1073 "swap_info %d in list but !SWP_WRITEOK\n",
1075 __del_from_avail_list(si
);
1076 spin_unlock(&si
->lock
);
1079 if (size
== SWAPFILE_CLUSTER
) {
1080 if (si
->flags
& SWP_BLKDEV
)
1081 n_ret
= swap_alloc_cluster(si
, swp_entries
);
1083 n_ret
= scan_swap_map_slots(si
, SWAP_HAS_CACHE
,
1084 n_goal
, swp_entries
);
1085 spin_unlock(&si
->lock
);
1086 if (n_ret
|| size
== SWAPFILE_CLUSTER
)
1088 pr_debug("scan_swap_map of si %d failed to find offset\n",
1091 spin_lock(&swap_avail_lock
);
1094 * if we got here, it's likely that si was almost full before,
1095 * and since scan_swap_map() can drop the si->lock, multiple
1096 * callers probably all tried to get a page from the same si
1097 * and it filled up before we could get one; or, the si filled
1098 * up between us dropping swap_avail_lock and taking si->lock.
1099 * Since we dropped the swap_avail_lock, the swap_avail_head
1100 * list may have been modified; so if next is still in the
1101 * swap_avail_head list then try it, otherwise start over
1102 * if we have not gotten any slots.
1104 if (plist_node_empty(&next
->avail_lists
[node
]))
1108 spin_unlock(&swap_avail_lock
);
1112 atomic_long_add((long)(n_goal
- n_ret
) * size
,
1118 /* The only caller of this function is now suspend routine */
1119 swp_entry_t
get_swap_page_of_type(int type
)
1121 struct swap_info_struct
*si
= swap_type_to_swap_info(type
);
1127 spin_lock(&si
->lock
);
1128 if (si
->flags
& SWP_WRITEOK
) {
1129 /* This is called for allocating swap entry, not cache */
1130 offset
= scan_swap_map(si
, 1);
1132 atomic_long_dec(&nr_swap_pages
);
1133 spin_unlock(&si
->lock
);
1134 return swp_entry(type
, offset
);
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 (data_race(!(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 (data_race(!p
->swap_map
[swp_offset(entry
)]))
1183 pr_err("swap_info_get: %s%08lx\n", Unused_offset
, entry
.val
);
1188 static struct swap_info_struct
*swap_info_get(swp_entry_t entry
)
1190 struct swap_info_struct
*p
;
1192 p
= _swap_info_get(entry
);
1194 spin_lock(&p
->lock
);
1198 static struct swap_info_struct
*swap_info_get_cont(swp_entry_t entry
,
1199 struct swap_info_struct
*q
)
1201 struct swap_info_struct
*p
;
1203 p
= _swap_info_get(entry
);
1207 spin_unlock(&q
->lock
);
1209 spin_lock(&p
->lock
);
1214 static unsigned char __swap_entry_free_locked(struct swap_info_struct
*p
,
1215 unsigned long offset
,
1216 unsigned char usage
)
1218 unsigned char count
;
1219 unsigned char has_cache
;
1221 count
= p
->swap_map
[offset
];
1223 has_cache
= count
& SWAP_HAS_CACHE
;
1224 count
&= ~SWAP_HAS_CACHE
;
1226 if (usage
== SWAP_HAS_CACHE
) {
1227 VM_BUG_ON(!has_cache
);
1229 } else if (count
== SWAP_MAP_SHMEM
) {
1231 * Or we could insist on shmem.c using a special
1232 * swap_shmem_free() and free_shmem_swap_and_cache()...
1235 } else if ((count
& ~COUNT_CONTINUED
) <= SWAP_MAP_MAX
) {
1236 if (count
== COUNT_CONTINUED
) {
1237 if (swap_count_continued(p
, offset
, count
))
1238 count
= SWAP_MAP_MAX
| COUNT_CONTINUED
;
1240 count
= SWAP_MAP_MAX
;
1245 usage
= count
| has_cache
;
1247 WRITE_ONCE(p
->swap_map
[offset
], usage
);
1249 WRITE_ONCE(p
->swap_map
[offset
], SWAP_HAS_CACHE
);
1255 * Check whether swap entry is valid in the swap device. If so,
1256 * return pointer to swap_info_struct, and keep the swap entry valid
1257 * via preventing the swap device from being swapoff, until
1258 * put_swap_device() is called. Otherwise return NULL.
1260 * The entirety of the RCU read critical section must come before the
1261 * return from or after the call to synchronize_rcu() in
1262 * enable_swap_info() or swapoff(). So if "si->flags & SWP_VALID" is
1263 * true, the si->map, si->cluster_info, etc. must be valid in the
1266 * Notice that swapoff or swapoff+swapon can still happen before the
1267 * rcu_read_lock() in get_swap_device() or after the rcu_read_unlock()
1268 * in put_swap_device() if there isn't any other way to prevent
1269 * swapoff, such as page lock, page table lock, etc. The caller must
1270 * be prepared for that. For example, the following situation is
1275 * ... swapoff+swapon
1276 * __read_swap_cache_async()
1277 * swapcache_prepare()
1278 * __swap_duplicate()
1280 * // verify PTE not changed
1282 * In __swap_duplicate(), the swap_map need to be checked before
1283 * changing partly because the specified swap entry may be for another
1284 * swap device which has been swapoff. And in do_swap_page(), after
1285 * the page is read from the swap device, the PTE is verified not
1286 * changed with the page table locked to check whether the swap device
1287 * has been swapoff or swapoff+swapon.
1289 struct swap_info_struct
*get_swap_device(swp_entry_t entry
)
1291 struct swap_info_struct
*si
;
1292 unsigned long offset
;
1296 si
= swp_swap_info(entry
);
1301 if (data_race(!(si
->flags
& SWP_VALID
)))
1303 offset
= swp_offset(entry
);
1304 if (offset
>= si
->max
)
1309 pr_err("%s: %s%08lx\n", __func__
, Bad_file
, entry
.val
);
1317 static unsigned char __swap_entry_free(struct swap_info_struct
*p
,
1320 struct swap_cluster_info
*ci
;
1321 unsigned long offset
= swp_offset(entry
);
1322 unsigned char usage
;
1324 ci
= lock_cluster_or_swap_info(p
, offset
);
1325 usage
= __swap_entry_free_locked(p
, offset
, 1);
1326 unlock_cluster_or_swap_info(p
, ci
);
1328 free_swap_slot(entry
);
1333 static void swap_entry_free(struct swap_info_struct
*p
, swp_entry_t entry
)
1335 struct swap_cluster_info
*ci
;
1336 unsigned long offset
= swp_offset(entry
);
1337 unsigned char count
;
1339 ci
= lock_cluster(p
, offset
);
1340 count
= p
->swap_map
[offset
];
1341 VM_BUG_ON(count
!= SWAP_HAS_CACHE
);
1342 p
->swap_map
[offset
] = 0;
1343 dec_cluster_info_page(p
, p
->cluster_info
, offset
);
1346 mem_cgroup_uncharge_swap(entry
, 1);
1347 swap_range_free(p
, offset
, 1);
1351 * Caller has made sure that the swap device corresponding to entry
1352 * is still around or has not been recycled.
1354 void swap_free(swp_entry_t entry
)
1356 struct swap_info_struct
*p
;
1358 p
= _swap_info_get(entry
);
1360 __swap_entry_free(p
, entry
);
1364 * Called after dropping swapcache to decrease refcnt to swap entries.
1366 void put_swap_page(struct page
*page
, swp_entry_t entry
)
1368 unsigned long offset
= swp_offset(entry
);
1369 unsigned long idx
= offset
/ SWAPFILE_CLUSTER
;
1370 struct swap_cluster_info
*ci
;
1371 struct swap_info_struct
*si
;
1373 unsigned int i
, free_entries
= 0;
1375 int size
= swap_entry_size(thp_nr_pages(page
));
1377 si
= _swap_info_get(entry
);
1381 ci
= lock_cluster_or_swap_info(si
, offset
);
1382 if (size
== SWAPFILE_CLUSTER
) {
1383 VM_BUG_ON(!cluster_is_huge(ci
));
1384 map
= si
->swap_map
+ offset
;
1385 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++) {
1387 VM_BUG_ON(!(val
& SWAP_HAS_CACHE
));
1388 if (val
== SWAP_HAS_CACHE
)
1391 cluster_clear_huge(ci
);
1392 if (free_entries
== SWAPFILE_CLUSTER
) {
1393 unlock_cluster_or_swap_info(si
, ci
);
1394 spin_lock(&si
->lock
);
1395 mem_cgroup_uncharge_swap(entry
, SWAPFILE_CLUSTER
);
1396 swap_free_cluster(si
, idx
);
1397 spin_unlock(&si
->lock
);
1401 for (i
= 0; i
< size
; i
++, entry
.val
++) {
1402 if (!__swap_entry_free_locked(si
, offset
+ i
, SWAP_HAS_CACHE
)) {
1403 unlock_cluster_or_swap_info(si
, ci
);
1404 free_swap_slot(entry
);
1407 lock_cluster_or_swap_info(si
, offset
);
1410 unlock_cluster_or_swap_info(si
, ci
);
1413 #ifdef CONFIG_THP_SWAP
1414 int split_swap_cluster(swp_entry_t entry
)
1416 struct swap_info_struct
*si
;
1417 struct swap_cluster_info
*ci
;
1418 unsigned long offset
= swp_offset(entry
);
1420 si
= _swap_info_get(entry
);
1423 ci
= lock_cluster(si
, offset
);
1424 cluster_clear_huge(ci
);
1430 static int swp_entry_cmp(const void *ent1
, const void *ent2
)
1432 const swp_entry_t
*e1
= ent1
, *e2
= ent2
;
1434 return (int)swp_type(*e1
) - (int)swp_type(*e2
);
1437 void swapcache_free_entries(swp_entry_t
*entries
, int n
)
1439 struct swap_info_struct
*p
, *prev
;
1449 * Sort swap entries by swap device, so each lock is only taken once.
1450 * nr_swapfiles isn't absolutely correct, but the overhead of sort() is
1451 * so low that it isn't necessary to optimize further.
1453 if (nr_swapfiles
> 1)
1454 sort(entries
, n
, sizeof(entries
[0]), swp_entry_cmp
, NULL
);
1455 for (i
= 0; i
< n
; ++i
) {
1456 p
= swap_info_get_cont(entries
[i
], prev
);
1458 swap_entry_free(p
, entries
[i
]);
1462 spin_unlock(&p
->lock
);
1466 * How many references to page are currently swapped out?
1467 * This does not give an exact answer when swap count is continued,
1468 * but does include the high COUNT_CONTINUED flag to allow for that.
1470 int page_swapcount(struct page
*page
)
1473 struct swap_info_struct
*p
;
1474 struct swap_cluster_info
*ci
;
1476 unsigned long offset
;
1478 entry
.val
= page_private(page
);
1479 p
= _swap_info_get(entry
);
1481 offset
= swp_offset(entry
);
1482 ci
= lock_cluster_or_swap_info(p
, offset
);
1483 count
= swap_count(p
->swap_map
[offset
]);
1484 unlock_cluster_or_swap_info(p
, ci
);
1489 int __swap_count(swp_entry_t entry
)
1491 struct swap_info_struct
*si
;
1492 pgoff_t offset
= swp_offset(entry
);
1495 si
= get_swap_device(entry
);
1497 count
= swap_count(si
->swap_map
[offset
]);
1498 put_swap_device(si
);
1503 static int swap_swapcount(struct swap_info_struct
*si
, swp_entry_t entry
)
1506 pgoff_t offset
= swp_offset(entry
);
1507 struct swap_cluster_info
*ci
;
1509 ci
= lock_cluster_or_swap_info(si
, offset
);
1510 count
= swap_count(si
->swap_map
[offset
]);
1511 unlock_cluster_or_swap_info(si
, ci
);
1516 * How many references to @entry are currently swapped out?
1517 * This does not give an exact answer when swap count is continued,
1518 * but does include the high COUNT_CONTINUED flag to allow for that.
1520 int __swp_swapcount(swp_entry_t entry
)
1523 struct swap_info_struct
*si
;
1525 si
= get_swap_device(entry
);
1527 count
= swap_swapcount(si
, entry
);
1528 put_swap_device(si
);
1534 * How many references to @entry are currently swapped out?
1535 * This considers COUNT_CONTINUED so it returns exact answer.
1537 int swp_swapcount(swp_entry_t entry
)
1539 int count
, tmp_count
, n
;
1540 struct swap_info_struct
*p
;
1541 struct swap_cluster_info
*ci
;
1546 p
= _swap_info_get(entry
);
1550 offset
= swp_offset(entry
);
1552 ci
= lock_cluster_or_swap_info(p
, offset
);
1554 count
= swap_count(p
->swap_map
[offset
]);
1555 if (!(count
& COUNT_CONTINUED
))
1558 count
&= ~COUNT_CONTINUED
;
1559 n
= SWAP_MAP_MAX
+ 1;
1561 page
= vmalloc_to_page(p
->swap_map
+ offset
);
1562 offset
&= ~PAGE_MASK
;
1563 VM_BUG_ON(page_private(page
) != SWP_CONTINUED
);
1566 page
= list_next_entry(page
, lru
);
1567 map
= kmap_atomic(page
);
1568 tmp_count
= map
[offset
];
1571 count
+= (tmp_count
& ~COUNT_CONTINUED
) * n
;
1572 n
*= (SWAP_CONT_MAX
+ 1);
1573 } while (tmp_count
& COUNT_CONTINUED
);
1575 unlock_cluster_or_swap_info(p
, ci
);
1579 static bool swap_page_trans_huge_swapped(struct swap_info_struct
*si
,
1582 struct swap_cluster_info
*ci
;
1583 unsigned char *map
= si
->swap_map
;
1584 unsigned long roffset
= swp_offset(entry
);
1585 unsigned long offset
= round_down(roffset
, SWAPFILE_CLUSTER
);
1589 ci
= lock_cluster_or_swap_info(si
, offset
);
1590 if (!ci
|| !cluster_is_huge(ci
)) {
1591 if (swap_count(map
[roffset
]))
1595 for (i
= 0; i
< SWAPFILE_CLUSTER
; i
++) {
1596 if (swap_count(map
[offset
+ i
])) {
1602 unlock_cluster_or_swap_info(si
, ci
);
1606 static bool page_swapped(struct page
*page
)
1609 struct swap_info_struct
*si
;
1611 if (!IS_ENABLED(CONFIG_THP_SWAP
) || likely(!PageTransCompound(page
)))
1612 return page_swapcount(page
) != 0;
1614 page
= compound_head(page
);
1615 entry
.val
= page_private(page
);
1616 si
= _swap_info_get(entry
);
1618 return swap_page_trans_huge_swapped(si
, entry
);
1622 static int page_trans_huge_map_swapcount(struct page
*page
, int *total_mapcount
,
1623 int *total_swapcount
)
1625 int i
, map_swapcount
, _total_mapcount
, _total_swapcount
;
1626 unsigned long offset
= 0;
1627 struct swap_info_struct
*si
;
1628 struct swap_cluster_info
*ci
= NULL
;
1629 unsigned char *map
= NULL
;
1630 int mapcount
, swapcount
= 0;
1632 /* hugetlbfs shouldn't call it */
1633 VM_BUG_ON_PAGE(PageHuge(page
), page
);
1635 if (!IS_ENABLED(CONFIG_THP_SWAP
) || likely(!PageTransCompound(page
))) {
1636 mapcount
= page_trans_huge_mapcount(page
, total_mapcount
);
1637 if (PageSwapCache(page
))
1638 swapcount
= page_swapcount(page
);
1639 if (total_swapcount
)
1640 *total_swapcount
= swapcount
;
1641 return mapcount
+ swapcount
;
1644 page
= compound_head(page
);
1646 _total_mapcount
= _total_swapcount
= map_swapcount
= 0;
1647 if (PageSwapCache(page
)) {
1650 entry
.val
= page_private(page
);
1651 si
= _swap_info_get(entry
);
1654 offset
= swp_offset(entry
);
1658 ci
= lock_cluster(si
, offset
);
1659 for (i
= 0; i
< HPAGE_PMD_NR
; i
++) {
1660 mapcount
= atomic_read(&page
[i
]._mapcount
) + 1;
1661 _total_mapcount
+= mapcount
;
1663 swapcount
= swap_count(map
[offset
+ i
]);
1664 _total_swapcount
+= swapcount
;
1666 map_swapcount
= max(map_swapcount
, mapcount
+ swapcount
);
1669 if (PageDoubleMap(page
)) {
1671 _total_mapcount
-= HPAGE_PMD_NR
;
1673 mapcount
= compound_mapcount(page
);
1674 map_swapcount
+= mapcount
;
1675 _total_mapcount
+= mapcount
;
1677 *total_mapcount
= _total_mapcount
;
1678 if (total_swapcount
)
1679 *total_swapcount
= _total_swapcount
;
1681 return map_swapcount
;
1685 * We can write to an anon page without COW if there are no other references
1686 * to it. And as a side-effect, free up its swap: because the old content
1687 * on disk will never be read, and seeking back there to write new content
1688 * later would only waste time away from clustering.
1690 * NOTE: total_map_swapcount should not be relied upon by the caller if
1691 * reuse_swap_page() returns false, but it may be always overwritten
1692 * (see the other implementation for CONFIG_SWAP=n).
1694 bool reuse_swap_page(struct page
*page
, int *total_map_swapcount
)
1696 int count
, total_mapcount
, total_swapcount
;
1698 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1699 if (unlikely(PageKsm(page
)))
1701 count
= page_trans_huge_map_swapcount(page
, &total_mapcount
,
1703 if (total_map_swapcount
)
1704 *total_map_swapcount
= total_mapcount
+ total_swapcount
;
1705 if (count
== 1 && PageSwapCache(page
) &&
1706 (likely(!PageTransCompound(page
)) ||
1707 /* The remaining swap count will be freed soon */
1708 total_swapcount
== page_swapcount(page
))) {
1709 if (!PageWriteback(page
)) {
1710 page
= compound_head(page
);
1711 delete_from_swap_cache(page
);
1715 struct swap_info_struct
*p
;
1717 entry
.val
= page_private(page
);
1718 p
= swap_info_get(entry
);
1719 if (p
->flags
& SWP_STABLE_WRITES
) {
1720 spin_unlock(&p
->lock
);
1723 spin_unlock(&p
->lock
);
1731 * If swap is getting full, or if there are no more mappings of this page,
1732 * then try_to_free_swap is called to free its swap space.
1734 int try_to_free_swap(struct page
*page
)
1736 VM_BUG_ON_PAGE(!PageLocked(page
), page
);
1738 if (!PageSwapCache(page
))
1740 if (PageWriteback(page
))
1742 if (page_swapped(page
))
1746 * Once hibernation has begun to create its image of memory,
1747 * there's a danger that one of the calls to try_to_free_swap()
1748 * - most probably a call from __try_to_reclaim_swap() while
1749 * hibernation is allocating its own swap pages for the image,
1750 * but conceivably even a call from memory reclaim - will free
1751 * the swap from a page which has already been recorded in the
1752 * image as a clean swapcache page, and then reuse its swap for
1753 * another page of the image. On waking from hibernation, the
1754 * original page might be freed under memory pressure, then
1755 * later read back in from swap, now with the wrong data.
1757 * Hibernation suspends storage while it is writing the image
1758 * to disk so check that here.
1760 if (pm_suspended_storage())
1763 page
= compound_head(page
);
1764 delete_from_swap_cache(page
);
1770 * Free the swap entry like above, but also try to
1771 * free the page cache entry if it is the last user.
1773 int free_swap_and_cache(swp_entry_t entry
)
1775 struct swap_info_struct
*p
;
1776 unsigned char count
;
1778 if (non_swap_entry(entry
))
1781 p
= _swap_info_get(entry
);
1783 count
= __swap_entry_free(p
, entry
);
1784 if (count
== SWAP_HAS_CACHE
&&
1785 !swap_page_trans_huge_swapped(p
, entry
))
1786 __try_to_reclaim_swap(p
, swp_offset(entry
),
1787 TTRS_UNMAPPED
| TTRS_FULL
);
1792 #ifdef CONFIG_HIBERNATION
1794 * Find the swap type that corresponds to given device (if any).
1796 * @offset - number of the PAGE_SIZE-sized block of the device, starting
1797 * from 0, in which the swap header is expected to be located.
1799 * This is needed for the suspend to disk (aka swsusp).
1801 int swap_type_of(dev_t device
, sector_t offset
)
1808 spin_lock(&swap_lock
);
1809 for (type
= 0; type
< nr_swapfiles
; type
++) {
1810 struct swap_info_struct
*sis
= swap_info
[type
];
1812 if (!(sis
->flags
& SWP_WRITEOK
))
1815 if (device
== sis
->bdev
->bd_dev
) {
1816 struct swap_extent
*se
= first_se(sis
);
1818 if (se
->start_block
== offset
) {
1819 spin_unlock(&swap_lock
);
1824 spin_unlock(&swap_lock
);
1828 int find_first_swap(dev_t
*device
)
1832 spin_lock(&swap_lock
);
1833 for (type
= 0; type
< nr_swapfiles
; type
++) {
1834 struct swap_info_struct
*sis
= swap_info
[type
];
1836 if (!(sis
->flags
& SWP_WRITEOK
))
1838 *device
= sis
->bdev
->bd_dev
;
1839 spin_unlock(&swap_lock
);
1842 spin_unlock(&swap_lock
);
1847 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
1848 * corresponding to given index in swap_info (swap type).
1850 sector_t
swapdev_block(int type
, pgoff_t offset
)
1852 struct swap_info_struct
*si
= swap_type_to_swap_info(type
);
1853 struct swap_extent
*se
;
1855 if (!si
|| !(si
->flags
& SWP_WRITEOK
))
1857 se
= offset_to_swap_extent(si
, offset
);
1858 return se
->start_block
+ (offset
- se
->start_page
);
1862 * Return either the total number of swap pages of given type, or the number
1863 * of free pages of that type (depending on @free)
1865 * This is needed for software suspend
1867 unsigned int count_swap_pages(int type
, int free
)
1871 spin_lock(&swap_lock
);
1872 if ((unsigned int)type
< nr_swapfiles
) {
1873 struct swap_info_struct
*sis
= swap_info
[type
];
1875 spin_lock(&sis
->lock
);
1876 if (sis
->flags
& SWP_WRITEOK
) {
1879 n
-= sis
->inuse_pages
;
1881 spin_unlock(&sis
->lock
);
1883 spin_unlock(&swap_lock
);
1886 #endif /* CONFIG_HIBERNATION */
1888 static inline int pte_same_as_swp(pte_t pte
, pte_t swp_pte
)
1890 return pte_same(pte_swp_clear_soft_dirty(pte
), swp_pte
);
1894 * No need to decide whether this PTE shares the swap entry with others,
1895 * just let do_wp_page work it out if a write is requested later - to
1896 * force COW, vm_page_prot omits write permission from any private vma.
1898 static int unuse_pte(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1899 unsigned long addr
, swp_entry_t entry
, struct page
*page
)
1901 struct page
*swapcache
;
1907 page
= ksm_might_need_to_copy(page
, vma
, addr
);
1908 if (unlikely(!page
))
1911 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
1912 if (unlikely(!pte_same_as_swp(*pte
, swp_entry_to_pte(entry
)))) {
1917 dec_mm_counter(vma
->vm_mm
, MM_SWAPENTS
);
1918 inc_mm_counter(vma
->vm_mm
, MM_ANONPAGES
);
1920 set_pte_at(vma
->vm_mm
, addr
, pte
,
1921 pte_mkold(mk_pte(page
, vma
->vm_page_prot
)));
1922 if (page
== swapcache
) {
1923 page_add_anon_rmap(page
, vma
, addr
, false);
1924 } else { /* ksm created a completely new copy */
1925 page_add_new_anon_rmap(page
, vma
, addr
, false);
1926 lru_cache_add_inactive_or_unevictable(page
, vma
);
1930 pte_unmap_unlock(pte
, ptl
);
1931 if (page
!= swapcache
) {
1938 static int unuse_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
1939 unsigned long addr
, unsigned long end
,
1940 unsigned int type
, bool frontswap
,
1941 unsigned long *fs_pages_to_unuse
)
1946 struct swap_info_struct
*si
;
1947 unsigned long offset
;
1949 volatile unsigned char *swap_map
;
1951 si
= swap_info
[type
];
1952 pte
= pte_offset_map(pmd
, addr
);
1954 if (!is_swap_pte(*pte
))
1957 entry
= pte_to_swp_entry(*pte
);
1958 if (swp_type(entry
) != type
)
1961 offset
= swp_offset(entry
);
1962 if (frontswap
&& !frontswap_test(si
, offset
))
1966 swap_map
= &si
->swap_map
[offset
];
1967 page
= lookup_swap_cache(entry
, vma
, addr
);
1969 struct vm_fault vmf
= {
1975 page
= swapin_readahead(entry
, GFP_HIGHUSER_MOVABLE
,
1979 if (*swap_map
== 0 || *swap_map
== SWAP_MAP_BAD
)
1985 wait_on_page_writeback(page
);
1986 ret
= unuse_pte(vma
, pmd
, addr
, entry
, page
);
1993 try_to_free_swap(page
);
1997 if (*fs_pages_to_unuse
&& !--(*fs_pages_to_unuse
)) {
1998 ret
= FRONTSWAP_PAGES_UNUSED
;
2002 pte
= pte_offset_map(pmd
, addr
);
2003 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
2011 static inline int unuse_pmd_range(struct vm_area_struct
*vma
, pud_t
*pud
,
2012 unsigned long addr
, unsigned long end
,
2013 unsigned int type
, bool frontswap
,
2014 unsigned long *fs_pages_to_unuse
)
2020 pmd
= pmd_offset(pud
, addr
);
2023 next
= pmd_addr_end(addr
, end
);
2024 if (pmd_none_or_trans_huge_or_clear_bad(pmd
))
2026 ret
= unuse_pte_range(vma
, pmd
, addr
, next
, type
,
2027 frontswap
, fs_pages_to_unuse
);
2030 } while (pmd
++, addr
= next
, addr
!= end
);
2034 static inline int unuse_pud_range(struct vm_area_struct
*vma
, p4d_t
*p4d
,
2035 unsigned long addr
, unsigned long end
,
2036 unsigned int type
, bool frontswap
,
2037 unsigned long *fs_pages_to_unuse
)
2043 pud
= pud_offset(p4d
, addr
);
2045 next
= pud_addr_end(addr
, end
);
2046 if (pud_none_or_clear_bad(pud
))
2048 ret
= unuse_pmd_range(vma
, pud
, addr
, next
, type
,
2049 frontswap
, fs_pages_to_unuse
);
2052 } while (pud
++, addr
= next
, addr
!= end
);
2056 static inline int unuse_p4d_range(struct vm_area_struct
*vma
, pgd_t
*pgd
,
2057 unsigned long addr
, unsigned long end
,
2058 unsigned int type
, bool frontswap
,
2059 unsigned long *fs_pages_to_unuse
)
2065 p4d
= p4d_offset(pgd
, addr
);
2067 next
= p4d_addr_end(addr
, end
);
2068 if (p4d_none_or_clear_bad(p4d
))
2070 ret
= unuse_pud_range(vma
, p4d
, addr
, next
, type
,
2071 frontswap
, fs_pages_to_unuse
);
2074 } while (p4d
++, addr
= next
, addr
!= end
);
2078 static int unuse_vma(struct vm_area_struct
*vma
, unsigned int type
,
2079 bool frontswap
, unsigned long *fs_pages_to_unuse
)
2082 unsigned long addr
, end
, next
;
2085 addr
= vma
->vm_start
;
2088 pgd
= pgd_offset(vma
->vm_mm
, addr
);
2090 next
= pgd_addr_end(addr
, end
);
2091 if (pgd_none_or_clear_bad(pgd
))
2093 ret
= unuse_p4d_range(vma
, pgd
, addr
, next
, type
,
2094 frontswap
, fs_pages_to_unuse
);
2097 } while (pgd
++, addr
= next
, addr
!= end
);
2101 static int unuse_mm(struct mm_struct
*mm
, unsigned int type
,
2102 bool frontswap
, unsigned long *fs_pages_to_unuse
)
2104 struct vm_area_struct
*vma
;
2108 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
2109 if (vma
->anon_vma
) {
2110 ret
= unuse_vma(vma
, type
, frontswap
,
2117 mmap_read_unlock(mm
);
2122 * Scan swap_map (or frontswap_map if frontswap parameter is true)
2123 * from current position to next entry still in use. Return 0
2124 * if there are no inuse entries after prev till end of the map.
2126 static unsigned int find_next_to_unuse(struct swap_info_struct
*si
,
2127 unsigned int prev
, bool frontswap
)
2130 unsigned char count
;
2133 * No need for swap_lock here: we're just looking
2134 * for whether an entry is in use, not modifying it; false
2135 * hits are okay, and sys_swapoff() has already prevented new
2136 * allocations from this area (while holding swap_lock).
2138 for (i
= prev
+ 1; i
< si
->max
; i
++) {
2139 count
= READ_ONCE(si
->swap_map
[i
]);
2140 if (count
&& swap_count(count
) != SWAP_MAP_BAD
)
2141 if (!frontswap
|| frontswap_test(si
, i
))
2143 if ((i
% LATENCY_LIMIT
) == 0)
2154 * If the boolean frontswap is true, only unuse pages_to_unuse pages;
2155 * pages_to_unuse==0 means all pages; ignored if frontswap is false
2157 int try_to_unuse(unsigned int type
, bool frontswap
,
2158 unsigned long pages_to_unuse
)
2160 struct mm_struct
*prev_mm
;
2161 struct mm_struct
*mm
;
2162 struct list_head
*p
;
2164 struct swap_info_struct
*si
= swap_info
[type
];
2169 if (!READ_ONCE(si
->inuse_pages
))
2176 retval
= shmem_unuse(type
, frontswap
, &pages_to_unuse
);
2183 spin_lock(&mmlist_lock
);
2184 p
= &init_mm
.mmlist
;
2185 while (READ_ONCE(si
->inuse_pages
) &&
2186 !signal_pending(current
) &&
2187 (p
= p
->next
) != &init_mm
.mmlist
) {
2189 mm
= list_entry(p
, struct mm_struct
, mmlist
);
2190 if (!mmget_not_zero(mm
))
2192 spin_unlock(&mmlist_lock
);
2195 retval
= unuse_mm(mm
, type
, frontswap
, &pages_to_unuse
);
2203 * Make sure that we aren't completely killing
2204 * interactive performance.
2207 spin_lock(&mmlist_lock
);
2209 spin_unlock(&mmlist_lock
);
2214 while (READ_ONCE(si
->inuse_pages
) &&
2215 !signal_pending(current
) &&
2216 (i
= find_next_to_unuse(si
, i
, frontswap
)) != 0) {
2218 entry
= swp_entry(type
, i
);
2219 page
= find_get_page(swap_address_space(entry
), i
);
2224 * It is conceivable that a racing task removed this page from
2225 * swap cache just before we acquired the page lock. The page
2226 * might even be back in swap cache on another swap area. But
2227 * that is okay, try_to_free_swap() only removes stale pages.
2230 wait_on_page_writeback(page
);
2231 try_to_free_swap(page
);
2236 * For frontswap, we just need to unuse pages_to_unuse, if
2237 * it was specified. Need not check frontswap again here as
2238 * we already zeroed out pages_to_unuse if not frontswap.
2240 if (pages_to_unuse
&& --pages_to_unuse
== 0)
2245 * Lets check again to see if there are still swap entries in the map.
2246 * If yes, we would need to do retry the unuse logic again.
2247 * Under global memory pressure, swap entries can be reinserted back
2248 * into process space after the mmlist loop above passes over them.
2250 * Limit the number of retries? No: when mmget_not_zero() above fails,
2251 * that mm is likely to be freeing swap from exit_mmap(), which proceeds
2252 * at its own independent pace; and even shmem_writepage() could have
2253 * been preempted after get_swap_page(), temporarily hiding that swap.
2254 * It's easy and robust (though cpu-intensive) just to keep retrying.
2256 if (READ_ONCE(si
->inuse_pages
)) {
2257 if (!signal_pending(current
))
2262 return (retval
== FRONTSWAP_PAGES_UNUSED
) ? 0 : retval
;
2266 * After a successful try_to_unuse, if no swap is now in use, we know
2267 * we can empty the mmlist. swap_lock must be held on entry and exit.
2268 * Note that mmlist_lock nests inside swap_lock, and an mm must be
2269 * added to the mmlist just after page_duplicate - before would be racy.
2271 static void drain_mmlist(void)
2273 struct list_head
*p
, *next
;
2276 for (type
= 0; type
< nr_swapfiles
; type
++)
2277 if (swap_info
[type
]->inuse_pages
)
2279 spin_lock(&mmlist_lock
);
2280 list_for_each_safe(p
, next
, &init_mm
.mmlist
)
2282 spin_unlock(&mmlist_lock
);
2286 * Free all of a swapdev's extent information
2288 static void destroy_swap_extents(struct swap_info_struct
*sis
)
2290 while (!RB_EMPTY_ROOT(&sis
->swap_extent_root
)) {
2291 struct rb_node
*rb
= sis
->swap_extent_root
.rb_node
;
2292 struct swap_extent
*se
= rb_entry(rb
, struct swap_extent
, rb_node
);
2294 rb_erase(rb
, &sis
->swap_extent_root
);
2298 if (sis
->flags
& SWP_ACTIVATED
) {
2299 struct file
*swap_file
= sis
->swap_file
;
2300 struct address_space
*mapping
= swap_file
->f_mapping
;
2302 sis
->flags
&= ~SWP_ACTIVATED
;
2303 if (mapping
->a_ops
->swap_deactivate
)
2304 mapping
->a_ops
->swap_deactivate(swap_file
);
2309 * Add a block range (and the corresponding page range) into this swapdev's
2312 * This function rather assumes that it is called in ascending page order.
2315 add_swap_extent(struct swap_info_struct
*sis
, unsigned long start_page
,
2316 unsigned long nr_pages
, sector_t start_block
)
2318 struct rb_node
**link
= &sis
->swap_extent_root
.rb_node
, *parent
= NULL
;
2319 struct swap_extent
*se
;
2320 struct swap_extent
*new_se
;
2323 * place the new node at the right most since the
2324 * function is called in ascending page order.
2328 link
= &parent
->rb_right
;
2332 se
= rb_entry(parent
, struct swap_extent
, rb_node
);
2333 BUG_ON(se
->start_page
+ se
->nr_pages
!= start_page
);
2334 if (se
->start_block
+ se
->nr_pages
== start_block
) {
2336 se
->nr_pages
+= nr_pages
;
2341 /* No merge, insert a new extent. */
2342 new_se
= kmalloc(sizeof(*se
), GFP_KERNEL
);
2345 new_se
->start_page
= start_page
;
2346 new_se
->nr_pages
= nr_pages
;
2347 new_se
->start_block
= start_block
;
2349 rb_link_node(&new_se
->rb_node
, parent
, link
);
2350 rb_insert_color(&new_se
->rb_node
, &sis
->swap_extent_root
);
2353 EXPORT_SYMBOL_GPL(add_swap_extent
);
2356 * A `swap extent' is a simple thing which maps a contiguous range of pages
2357 * onto a contiguous range of disk blocks. An ordered list of swap extents
2358 * is built at swapon time and is then used at swap_writepage/swap_readpage
2359 * time for locating where on disk a page belongs.
2361 * If the swapfile is an S_ISBLK block device, a single extent is installed.
2362 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
2363 * swap files identically.
2365 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
2366 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
2367 * swapfiles are handled *identically* after swapon time.
2369 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
2370 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
2371 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
2372 * requirements, they are simply tossed out - we will never use those blocks
2375 * For all swap devices we set S_SWAPFILE across the life of the swapon. This
2376 * prevents users from writing to the swap device, which will corrupt memory.
2378 * The amount of disk space which a single swap extent represents varies.
2379 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
2380 * extents in the list. To avoid much list walking, we cache the previous
2381 * search location in `curr_swap_extent', and start new searches from there.
2382 * This is extremely effective. The average number of iterations in
2383 * map_swap_page() has been measured at about 0.3 per page. - akpm.
2385 static int setup_swap_extents(struct swap_info_struct
*sis
, sector_t
*span
)
2387 struct file
*swap_file
= sis
->swap_file
;
2388 struct address_space
*mapping
= swap_file
->f_mapping
;
2389 struct inode
*inode
= mapping
->host
;
2392 if (S_ISBLK(inode
->i_mode
)) {
2393 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
2398 if (mapping
->a_ops
->swap_activate
) {
2399 ret
= mapping
->a_ops
->swap_activate(sis
, swap_file
, span
);
2401 sis
->flags
|= SWP_ACTIVATED
;
2403 sis
->flags
|= SWP_FS_OPS
;
2404 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
2410 return generic_swapfile_activate(sis
, swap_file
, span
);
2413 static int swap_node(struct swap_info_struct
*p
)
2415 struct block_device
*bdev
;
2420 bdev
= p
->swap_file
->f_inode
->i_sb
->s_bdev
;
2422 return bdev
? bdev
->bd_disk
->node_id
: NUMA_NO_NODE
;
2425 static void setup_swap_info(struct swap_info_struct
*p
, int prio
,
2426 unsigned char *swap_map
,
2427 struct swap_cluster_info
*cluster_info
)
2434 p
->prio
= --least_priority
;
2436 * the plist prio is negated because plist ordering is
2437 * low-to-high, while swap ordering is high-to-low
2439 p
->list
.prio
= -p
->prio
;
2442 p
->avail_lists
[i
].prio
= -p
->prio
;
2444 if (swap_node(p
) == i
)
2445 p
->avail_lists
[i
].prio
= 1;
2447 p
->avail_lists
[i
].prio
= -p
->prio
;
2450 p
->swap_map
= swap_map
;
2451 p
->cluster_info
= cluster_info
;
2454 static void _enable_swap_info(struct swap_info_struct
*p
)
2456 p
->flags
|= SWP_WRITEOK
| SWP_VALID
;
2457 atomic_long_add(p
->pages
, &nr_swap_pages
);
2458 total_swap_pages
+= p
->pages
;
2460 assert_spin_locked(&swap_lock
);
2462 * both lists are plists, and thus priority ordered.
2463 * swap_active_head needs to be priority ordered for swapoff(),
2464 * which on removal of any swap_info_struct with an auto-assigned
2465 * (i.e. negative) priority increments the auto-assigned priority
2466 * of any lower-priority swap_info_structs.
2467 * swap_avail_head needs to be priority ordered for get_swap_page(),
2468 * which allocates swap pages from the highest available priority
2471 plist_add(&p
->list
, &swap_active_head
);
2472 add_to_avail_list(p
);
2475 static void enable_swap_info(struct swap_info_struct
*p
, int prio
,
2476 unsigned char *swap_map
,
2477 struct swap_cluster_info
*cluster_info
,
2478 unsigned long *frontswap_map
)
2480 frontswap_init(p
->type
, frontswap_map
);
2481 spin_lock(&swap_lock
);
2482 spin_lock(&p
->lock
);
2483 setup_swap_info(p
, prio
, swap_map
, cluster_info
);
2484 spin_unlock(&p
->lock
);
2485 spin_unlock(&swap_lock
);
2487 * Guarantee swap_map, cluster_info, etc. fields are valid
2488 * between get/put_swap_device() if SWP_VALID bit is set
2491 spin_lock(&swap_lock
);
2492 spin_lock(&p
->lock
);
2493 _enable_swap_info(p
);
2494 spin_unlock(&p
->lock
);
2495 spin_unlock(&swap_lock
);
2498 static void reinsert_swap_info(struct swap_info_struct
*p
)
2500 spin_lock(&swap_lock
);
2501 spin_lock(&p
->lock
);
2502 setup_swap_info(p
, p
->prio
, p
->swap_map
, p
->cluster_info
);
2503 _enable_swap_info(p
);
2504 spin_unlock(&p
->lock
);
2505 spin_unlock(&swap_lock
);
2508 bool has_usable_swap(void)
2512 spin_lock(&swap_lock
);
2513 if (plist_head_empty(&swap_active_head
))
2515 spin_unlock(&swap_lock
);
2519 SYSCALL_DEFINE1(swapoff
, const char __user
*, specialfile
)
2521 struct swap_info_struct
*p
= NULL
;
2522 unsigned char *swap_map
;
2523 struct swap_cluster_info
*cluster_info
;
2524 unsigned long *frontswap_map
;
2525 struct file
*swap_file
, *victim
;
2526 struct address_space
*mapping
;
2527 struct inode
*inode
;
2528 struct filename
*pathname
;
2530 unsigned int old_block_size
;
2532 if (!capable(CAP_SYS_ADMIN
))
2535 BUG_ON(!current
->mm
);
2537 pathname
= getname(specialfile
);
2538 if (IS_ERR(pathname
))
2539 return PTR_ERR(pathname
);
2541 victim
= file_open_name(pathname
, O_RDWR
|O_LARGEFILE
, 0);
2542 err
= PTR_ERR(victim
);
2546 mapping
= victim
->f_mapping
;
2547 spin_lock(&swap_lock
);
2548 plist_for_each_entry(p
, &swap_active_head
, list
) {
2549 if (p
->flags
& SWP_WRITEOK
) {
2550 if (p
->swap_file
->f_mapping
== mapping
) {
2558 spin_unlock(&swap_lock
);
2561 if (!security_vm_enough_memory_mm(current
->mm
, p
->pages
))
2562 vm_unacct_memory(p
->pages
);
2565 spin_unlock(&swap_lock
);
2568 del_from_avail_list(p
);
2569 spin_lock(&p
->lock
);
2571 struct swap_info_struct
*si
= p
;
2574 plist_for_each_entry_continue(si
, &swap_active_head
, list
) {
2577 for_each_node(nid
) {
2578 if (si
->avail_lists
[nid
].prio
!= 1)
2579 si
->avail_lists
[nid
].prio
--;
2584 plist_del(&p
->list
, &swap_active_head
);
2585 atomic_long_sub(p
->pages
, &nr_swap_pages
);
2586 total_swap_pages
-= p
->pages
;
2587 p
->flags
&= ~SWP_WRITEOK
;
2588 spin_unlock(&p
->lock
);
2589 spin_unlock(&swap_lock
);
2591 disable_swap_slots_cache_lock();
2593 set_current_oom_origin();
2594 err
= try_to_unuse(p
->type
, false, 0); /* force unuse all pages */
2595 clear_current_oom_origin();
2598 /* re-insert swap space back into swap_list */
2599 reinsert_swap_info(p
);
2600 reenable_swap_slots_cache_unlock();
2604 reenable_swap_slots_cache_unlock();
2606 spin_lock(&swap_lock
);
2607 spin_lock(&p
->lock
);
2608 p
->flags
&= ~SWP_VALID
; /* mark swap device as invalid */
2609 spin_unlock(&p
->lock
);
2610 spin_unlock(&swap_lock
);
2612 * wait for swap operations protected by get/put_swap_device()
2617 flush_work(&p
->discard_work
);
2619 destroy_swap_extents(p
);
2620 if (p
->flags
& SWP_CONTINUED
)
2621 free_swap_count_continuations(p
);
2623 if (!p
->bdev
|| !blk_queue_nonrot(bdev_get_queue(p
->bdev
)))
2624 atomic_dec(&nr_rotate_swap
);
2626 mutex_lock(&swapon_mutex
);
2627 spin_lock(&swap_lock
);
2628 spin_lock(&p
->lock
);
2631 /* wait for anyone still in scan_swap_map */
2632 p
->highest_bit
= 0; /* cuts scans short */
2633 while (p
->flags
>= SWP_SCANNING
) {
2634 spin_unlock(&p
->lock
);
2635 spin_unlock(&swap_lock
);
2636 schedule_timeout_uninterruptible(1);
2637 spin_lock(&swap_lock
);
2638 spin_lock(&p
->lock
);
2641 swap_file
= p
->swap_file
;
2642 old_block_size
= p
->old_block_size
;
2643 p
->swap_file
= NULL
;
2645 swap_map
= p
->swap_map
;
2647 cluster_info
= p
->cluster_info
;
2648 p
->cluster_info
= NULL
;
2649 frontswap_map
= frontswap_map_get(p
);
2650 spin_unlock(&p
->lock
);
2651 spin_unlock(&swap_lock
);
2652 arch_swap_invalidate_area(p
->type
);
2653 frontswap_invalidate_area(p
->type
);
2654 frontswap_map_set(p
, NULL
);
2655 mutex_unlock(&swapon_mutex
);
2656 free_percpu(p
->percpu_cluster
);
2657 p
->percpu_cluster
= NULL
;
2658 free_percpu(p
->cluster_next_cpu
);
2659 p
->cluster_next_cpu
= NULL
;
2661 kvfree(cluster_info
);
2662 kvfree(frontswap_map
);
2663 /* Destroy swap account information */
2664 swap_cgroup_swapoff(p
->type
);
2665 exit_swap_address_space(p
->type
);
2667 inode
= mapping
->host
;
2668 if (S_ISBLK(inode
->i_mode
)) {
2669 struct block_device
*bdev
= I_BDEV(inode
);
2671 set_blocksize(bdev
, old_block_size
);
2672 blkdev_put(bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
2676 inode
->i_flags
&= ~S_SWAPFILE
;
2677 inode_unlock(inode
);
2678 filp_close(swap_file
, NULL
);
2681 * Clear the SWP_USED flag after all resources are freed so that swapon
2682 * can reuse this swap_info in alloc_swap_info() safely. It is ok to
2683 * not hold p->lock after we cleared its SWP_WRITEOK.
2685 spin_lock(&swap_lock
);
2687 spin_unlock(&swap_lock
);
2690 atomic_inc(&proc_poll_event
);
2691 wake_up_interruptible(&proc_poll_wait
);
2694 filp_close(victim
, NULL
);
2700 #ifdef CONFIG_PROC_FS
2701 static __poll_t
swaps_poll(struct file
*file
, poll_table
*wait
)
2703 struct seq_file
*seq
= file
->private_data
;
2705 poll_wait(file
, &proc_poll_wait
, wait
);
2707 if (seq
->poll_event
!= atomic_read(&proc_poll_event
)) {
2708 seq
->poll_event
= atomic_read(&proc_poll_event
);
2709 return EPOLLIN
| EPOLLRDNORM
| EPOLLERR
| EPOLLPRI
;
2712 return EPOLLIN
| EPOLLRDNORM
;
2716 static void *swap_start(struct seq_file
*swap
, loff_t
*pos
)
2718 struct swap_info_struct
*si
;
2722 mutex_lock(&swapon_mutex
);
2725 return SEQ_START_TOKEN
;
2727 for (type
= 0; (si
= swap_type_to_swap_info(type
)); type
++) {
2728 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
2737 static void *swap_next(struct seq_file
*swap
, void *v
, loff_t
*pos
)
2739 struct swap_info_struct
*si
= v
;
2742 if (v
== SEQ_START_TOKEN
)
2745 type
= si
->type
+ 1;
2748 for (; (si
= swap_type_to_swap_info(type
)); type
++) {
2749 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
2757 static void swap_stop(struct seq_file
*swap
, void *v
)
2759 mutex_unlock(&swapon_mutex
);
2762 static int swap_show(struct seq_file
*swap
, void *v
)
2764 struct swap_info_struct
*si
= v
;
2767 unsigned int bytes
, inuse
;
2769 if (si
== SEQ_START_TOKEN
) {
2770 seq_puts(swap
,"Filename\t\t\t\tType\t\tSize\t\tUsed\t\tPriority\n");
2774 bytes
= si
->pages
<< (PAGE_SHIFT
- 10);
2775 inuse
= si
->inuse_pages
<< (PAGE_SHIFT
- 10);
2777 file
= si
->swap_file
;
2778 len
= seq_file_path(swap
, file
, " \t\n\\");
2779 seq_printf(swap
, "%*s%s\t%u\t%s%u\t%s%d\n",
2780 len
< 40 ? 40 - len
: 1, " ",
2781 S_ISBLK(file_inode(file
)->i_mode
) ?
2782 "partition" : "file\t",
2783 bytes
, bytes
< 10000000 ? "\t" : "",
2784 inuse
, inuse
< 10000000 ? "\t" : "",
2789 static const struct seq_operations swaps_op
= {
2790 .start
= swap_start
,
2796 static int swaps_open(struct inode
*inode
, struct file
*file
)
2798 struct seq_file
*seq
;
2801 ret
= seq_open(file
, &swaps_op
);
2805 seq
= file
->private_data
;
2806 seq
->poll_event
= atomic_read(&proc_poll_event
);
2810 static const struct proc_ops swaps_proc_ops
= {
2811 .proc_flags
= PROC_ENTRY_PERMANENT
,
2812 .proc_open
= swaps_open
,
2813 .proc_read
= seq_read
,
2814 .proc_lseek
= seq_lseek
,
2815 .proc_release
= seq_release
,
2816 .proc_poll
= swaps_poll
,
2819 static int __init
procswaps_init(void)
2821 proc_create("swaps", 0, NULL
, &swaps_proc_ops
);
2824 __initcall(procswaps_init
);
2825 #endif /* CONFIG_PROC_FS */
2827 #ifdef MAX_SWAPFILES_CHECK
2828 static int __init
max_swapfiles_check(void)
2830 MAX_SWAPFILES_CHECK();
2833 late_initcall(max_swapfiles_check
);
2836 static struct swap_info_struct
*alloc_swap_info(void)
2838 struct swap_info_struct
*p
;
2839 struct swap_info_struct
*defer
= NULL
;
2843 p
= kvzalloc(struct_size(p
, avail_lists
, nr_node_ids
), GFP_KERNEL
);
2845 return ERR_PTR(-ENOMEM
);
2847 spin_lock(&swap_lock
);
2848 for (type
= 0; type
< nr_swapfiles
; type
++) {
2849 if (!(swap_info
[type
]->flags
& SWP_USED
))
2852 if (type
>= MAX_SWAPFILES
) {
2853 spin_unlock(&swap_lock
);
2855 return ERR_PTR(-EPERM
);
2857 if (type
>= nr_swapfiles
) {
2859 WRITE_ONCE(swap_info
[type
], p
);
2861 * Write swap_info[type] before nr_swapfiles, in case a
2862 * racing procfs swap_start() or swap_next() is reading them.
2863 * (We never shrink nr_swapfiles, we never free this entry.)
2866 WRITE_ONCE(nr_swapfiles
, nr_swapfiles
+ 1);
2869 p
= swap_info
[type
];
2871 * Do not memset this entry: a racing procfs swap_next()
2872 * would be relying on p->type to remain valid.
2875 p
->swap_extent_root
= RB_ROOT
;
2876 plist_node_init(&p
->list
, 0);
2878 plist_node_init(&p
->avail_lists
[i
], 0);
2879 p
->flags
= SWP_USED
;
2880 spin_unlock(&swap_lock
);
2882 spin_lock_init(&p
->lock
);
2883 spin_lock_init(&p
->cont_lock
);
2888 static int claim_swapfile(struct swap_info_struct
*p
, struct inode
*inode
)
2892 if (S_ISBLK(inode
->i_mode
)) {
2893 p
->bdev
= blkdev_get_by_dev(inode
->i_rdev
,
2894 FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
, p
);
2895 if (IS_ERR(p
->bdev
)) {
2896 error
= PTR_ERR(p
->bdev
);
2900 p
->old_block_size
= block_size(p
->bdev
);
2901 error
= set_blocksize(p
->bdev
, PAGE_SIZE
);
2905 * Zoned block devices contain zones that have a sequential
2906 * write only restriction. Hence zoned block devices are not
2907 * suitable for swapping. Disallow them here.
2909 if (blk_queue_is_zoned(p
->bdev
->bd_disk
->queue
))
2911 p
->flags
|= SWP_BLKDEV
;
2912 } else if (S_ISREG(inode
->i_mode
)) {
2913 p
->bdev
= inode
->i_sb
->s_bdev
;
2921 * Find out how many pages are allowed for a single swap device. There
2922 * are two limiting factors:
2923 * 1) the number of bits for the swap offset in the swp_entry_t type, and
2924 * 2) the number of bits in the swap pte, as defined by the different
2927 * In order to find the largest possible bit mask, a swap entry with
2928 * swap type 0 and swap offset ~0UL is created, encoded to a swap pte,
2929 * decoded to a swp_entry_t again, and finally the swap offset is
2932 * This will mask all the bits from the initial ~0UL mask that can't
2933 * be encoded in either the swp_entry_t or the architecture definition
2936 unsigned long generic_max_swapfile_size(void)
2938 return swp_offset(pte_to_swp_entry(
2939 swp_entry_to_pte(swp_entry(0, ~0UL)))) + 1;
2942 /* Can be overridden by an architecture for additional checks. */
2943 __weak
unsigned long max_swapfile_size(void)
2945 return generic_max_swapfile_size();
2948 static unsigned long read_swap_header(struct swap_info_struct
*p
,
2949 union swap_header
*swap_header
,
2950 struct inode
*inode
)
2953 unsigned long maxpages
;
2954 unsigned long swapfilepages
;
2955 unsigned long last_page
;
2957 if (memcmp("SWAPSPACE2", swap_header
->magic
.magic
, 10)) {
2958 pr_err("Unable to find swap-space signature\n");
2962 /* swap partition endianess hack... */
2963 if (swab32(swap_header
->info
.version
) == 1) {
2964 swab32s(&swap_header
->info
.version
);
2965 swab32s(&swap_header
->info
.last_page
);
2966 swab32s(&swap_header
->info
.nr_badpages
);
2967 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
2969 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++)
2970 swab32s(&swap_header
->info
.badpages
[i
]);
2972 /* Check the swap header's sub-version */
2973 if (swap_header
->info
.version
!= 1) {
2974 pr_warn("Unable to handle swap header version %d\n",
2975 swap_header
->info
.version
);
2980 p
->cluster_next
= 1;
2983 maxpages
= max_swapfile_size();
2984 last_page
= swap_header
->info
.last_page
;
2986 pr_warn("Empty swap-file\n");
2989 if (last_page
> maxpages
) {
2990 pr_warn("Truncating oversized swap area, only using %luk out of %luk\n",
2991 maxpages
<< (PAGE_SHIFT
- 10),
2992 last_page
<< (PAGE_SHIFT
- 10));
2994 if (maxpages
> last_page
) {
2995 maxpages
= last_page
+ 1;
2996 /* p->max is an unsigned int: don't overflow it */
2997 if ((unsigned int)maxpages
== 0)
2998 maxpages
= UINT_MAX
;
3000 p
->highest_bit
= maxpages
- 1;
3004 swapfilepages
= i_size_read(inode
) >> PAGE_SHIFT
;
3005 if (swapfilepages
&& maxpages
> swapfilepages
) {
3006 pr_warn("Swap area shorter than signature indicates\n");
3009 if (swap_header
->info
.nr_badpages
&& S_ISREG(inode
->i_mode
))
3011 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
3017 #define SWAP_CLUSTER_INFO_COLS \
3018 DIV_ROUND_UP(L1_CACHE_BYTES, sizeof(struct swap_cluster_info))
3019 #define SWAP_CLUSTER_SPACE_COLS \
3020 DIV_ROUND_UP(SWAP_ADDRESS_SPACE_PAGES, SWAPFILE_CLUSTER)
3021 #define SWAP_CLUSTER_COLS \
3022 max_t(unsigned int, SWAP_CLUSTER_INFO_COLS, SWAP_CLUSTER_SPACE_COLS)
3024 static int setup_swap_map_and_extents(struct swap_info_struct
*p
,
3025 union swap_header
*swap_header
,
3026 unsigned char *swap_map
,
3027 struct swap_cluster_info
*cluster_info
,
3028 unsigned long maxpages
,
3032 unsigned int nr_good_pages
;
3034 unsigned long nr_clusters
= DIV_ROUND_UP(maxpages
, SWAPFILE_CLUSTER
);
3035 unsigned long col
= p
->cluster_next
/ SWAPFILE_CLUSTER
% SWAP_CLUSTER_COLS
;
3036 unsigned long i
, idx
;
3038 nr_good_pages
= maxpages
- 1; /* omit header page */
3040 cluster_list_init(&p
->free_clusters
);
3041 cluster_list_init(&p
->discard_clusters
);
3043 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++) {
3044 unsigned int page_nr
= swap_header
->info
.badpages
[i
];
3045 if (page_nr
== 0 || page_nr
> swap_header
->info
.last_page
)
3047 if (page_nr
< maxpages
) {
3048 swap_map
[page_nr
] = SWAP_MAP_BAD
;
3051 * Haven't marked the cluster free yet, no list
3052 * operation involved
3054 inc_cluster_info_page(p
, cluster_info
, page_nr
);
3058 /* Haven't marked the cluster free yet, no list operation involved */
3059 for (i
= maxpages
; i
< round_up(maxpages
, SWAPFILE_CLUSTER
); i
++)
3060 inc_cluster_info_page(p
, cluster_info
, i
);
3062 if (nr_good_pages
) {
3063 swap_map
[0] = SWAP_MAP_BAD
;
3065 * Not mark the cluster free yet, no list
3066 * operation involved
3068 inc_cluster_info_page(p
, cluster_info
, 0);
3070 p
->pages
= nr_good_pages
;
3071 nr_extents
= setup_swap_extents(p
, span
);
3074 nr_good_pages
= p
->pages
;
3076 if (!nr_good_pages
) {
3077 pr_warn("Empty swap-file\n");
3086 * Reduce false cache line sharing between cluster_info and
3087 * sharing same address space.
3089 for (k
= 0; k
< SWAP_CLUSTER_COLS
; k
++) {
3090 j
= (k
+ col
) % SWAP_CLUSTER_COLS
;
3091 for (i
= 0; i
< DIV_ROUND_UP(nr_clusters
, SWAP_CLUSTER_COLS
); i
++) {
3092 idx
= i
* SWAP_CLUSTER_COLS
+ j
;
3093 if (idx
>= nr_clusters
)
3095 if (cluster_count(&cluster_info
[idx
]))
3097 cluster_set_flag(&cluster_info
[idx
], CLUSTER_FLAG_FREE
);
3098 cluster_list_add_tail(&p
->free_clusters
, cluster_info
,
3106 * Helper to sys_swapon determining if a given swap
3107 * backing device queue supports DISCARD operations.
3109 static bool swap_discardable(struct swap_info_struct
*si
)
3111 struct request_queue
*q
= bdev_get_queue(si
->bdev
);
3113 if (!q
|| !blk_queue_discard(q
))
3119 SYSCALL_DEFINE2(swapon
, const char __user
*, specialfile
, int, swap_flags
)
3121 struct swap_info_struct
*p
;
3122 struct filename
*name
;
3123 struct file
*swap_file
= NULL
;
3124 struct address_space
*mapping
;
3127 union swap_header
*swap_header
;
3130 unsigned long maxpages
;
3131 unsigned char *swap_map
= NULL
;
3132 struct swap_cluster_info
*cluster_info
= NULL
;
3133 unsigned long *frontswap_map
= NULL
;
3134 struct page
*page
= NULL
;
3135 struct inode
*inode
= NULL
;
3136 bool inced_nr_rotate_swap
= false;
3138 if (swap_flags
& ~SWAP_FLAGS_VALID
)
3141 if (!capable(CAP_SYS_ADMIN
))
3144 if (!swap_avail_heads
)
3147 p
= alloc_swap_info();
3151 INIT_WORK(&p
->discard_work
, swap_discard_work
);
3153 name
= getname(specialfile
);
3155 error
= PTR_ERR(name
);
3159 swap_file
= file_open_name(name
, O_RDWR
|O_LARGEFILE
, 0);
3160 if (IS_ERR(swap_file
)) {
3161 error
= PTR_ERR(swap_file
);
3166 p
->swap_file
= swap_file
;
3167 mapping
= swap_file
->f_mapping
;
3168 inode
= mapping
->host
;
3170 error
= claim_swapfile(p
, inode
);
3171 if (unlikely(error
))
3175 if (IS_SWAPFILE(inode
)) {
3177 goto bad_swap_unlock_inode
;
3181 * Read the swap header.
3183 if (!mapping
->a_ops
->readpage
) {
3185 goto bad_swap_unlock_inode
;
3187 page
= read_mapping_page(mapping
, 0, swap_file
);
3189 error
= PTR_ERR(page
);
3190 goto bad_swap_unlock_inode
;
3192 swap_header
= kmap(page
);
3194 maxpages
= read_swap_header(p
, swap_header
, inode
);
3195 if (unlikely(!maxpages
)) {
3197 goto bad_swap_unlock_inode
;
3200 /* OK, set up the swap map and apply the bad block list */
3201 swap_map
= vzalloc(maxpages
);
3204 goto bad_swap_unlock_inode
;
3207 if (p
->bdev
&& blk_queue_stable_writes(p
->bdev
->bd_disk
->queue
))
3208 p
->flags
|= SWP_STABLE_WRITES
;
3210 if (p
->bdev
&& p
->bdev
->bd_disk
->fops
->rw_page
)
3211 p
->flags
|= SWP_SYNCHRONOUS_IO
;
3213 if (p
->bdev
&& blk_queue_nonrot(bdev_get_queue(p
->bdev
))) {
3215 unsigned long ci
, nr_cluster
;
3217 p
->flags
|= SWP_SOLIDSTATE
;
3218 p
->cluster_next_cpu
= alloc_percpu(unsigned int);
3219 if (!p
->cluster_next_cpu
) {
3221 goto bad_swap_unlock_inode
;
3224 * select a random position to start with to help wear leveling
3227 for_each_possible_cpu(cpu
) {
3228 per_cpu(*p
->cluster_next_cpu
, cpu
) =
3229 1 + prandom_u32_max(p
->highest_bit
);
3231 nr_cluster
= DIV_ROUND_UP(maxpages
, SWAPFILE_CLUSTER
);
3233 cluster_info
= kvcalloc(nr_cluster
, sizeof(*cluster_info
),
3235 if (!cluster_info
) {
3237 goto bad_swap_unlock_inode
;
3240 for (ci
= 0; ci
< nr_cluster
; ci
++)
3241 spin_lock_init(&((cluster_info
+ ci
)->lock
));
3243 p
->percpu_cluster
= alloc_percpu(struct percpu_cluster
);
3244 if (!p
->percpu_cluster
) {
3246 goto bad_swap_unlock_inode
;
3248 for_each_possible_cpu(cpu
) {
3249 struct percpu_cluster
*cluster
;
3250 cluster
= per_cpu_ptr(p
->percpu_cluster
, cpu
);
3251 cluster_set_null(&cluster
->index
);
3254 atomic_inc(&nr_rotate_swap
);
3255 inced_nr_rotate_swap
= true;
3258 error
= swap_cgroup_swapon(p
->type
, maxpages
);
3260 goto bad_swap_unlock_inode
;
3262 nr_extents
= setup_swap_map_and_extents(p
, swap_header
, swap_map
,
3263 cluster_info
, maxpages
, &span
);
3264 if (unlikely(nr_extents
< 0)) {
3266 goto bad_swap_unlock_inode
;
3268 /* frontswap enabled? set up bit-per-page map for frontswap */
3269 if (IS_ENABLED(CONFIG_FRONTSWAP
))
3270 frontswap_map
= kvcalloc(BITS_TO_LONGS(maxpages
),
3274 if (p
->bdev
&&(swap_flags
& SWAP_FLAG_DISCARD
) && swap_discardable(p
)) {
3276 * When discard is enabled for swap with no particular
3277 * policy flagged, we set all swap discard flags here in
3278 * order to sustain backward compatibility with older
3279 * swapon(8) releases.
3281 p
->flags
|= (SWP_DISCARDABLE
| SWP_AREA_DISCARD
|
3285 * By flagging sys_swapon, a sysadmin can tell us to
3286 * either do single-time area discards only, or to just
3287 * perform discards for released swap page-clusters.
3288 * Now it's time to adjust the p->flags accordingly.
3290 if (swap_flags
& SWAP_FLAG_DISCARD_ONCE
)
3291 p
->flags
&= ~SWP_PAGE_DISCARD
;
3292 else if (swap_flags
& SWAP_FLAG_DISCARD_PAGES
)
3293 p
->flags
&= ~SWP_AREA_DISCARD
;
3295 /* issue a swapon-time discard if it's still required */
3296 if (p
->flags
& SWP_AREA_DISCARD
) {
3297 int err
= discard_swap(p
);
3299 pr_err("swapon: discard_swap(%p): %d\n",
3304 error
= init_swap_address_space(p
->type
, maxpages
);
3306 goto bad_swap_unlock_inode
;
3309 * Flush any pending IO and dirty mappings before we start using this
3312 inode
->i_flags
|= S_SWAPFILE
;
3313 error
= inode_drain_writes(inode
);
3315 inode
->i_flags
&= ~S_SWAPFILE
;
3316 goto free_swap_address_space
;
3319 mutex_lock(&swapon_mutex
);
3321 if (swap_flags
& SWAP_FLAG_PREFER
)
3323 (swap_flags
& SWAP_FLAG_PRIO_MASK
) >> SWAP_FLAG_PRIO_SHIFT
;
3324 enable_swap_info(p
, prio
, swap_map
, cluster_info
, frontswap_map
);
3326 pr_info("Adding %uk swap on %s. Priority:%d extents:%d across:%lluk %s%s%s%s%s\n",
3327 p
->pages
<<(PAGE_SHIFT
-10), name
->name
, p
->prio
,
3328 nr_extents
, (unsigned long long)span
<<(PAGE_SHIFT
-10),
3329 (p
->flags
& SWP_SOLIDSTATE
) ? "SS" : "",
3330 (p
->flags
& SWP_DISCARDABLE
) ? "D" : "",
3331 (p
->flags
& SWP_AREA_DISCARD
) ? "s" : "",
3332 (p
->flags
& SWP_PAGE_DISCARD
) ? "c" : "",
3333 (frontswap_map
) ? "FS" : "");
3335 mutex_unlock(&swapon_mutex
);
3336 atomic_inc(&proc_poll_event
);
3337 wake_up_interruptible(&proc_poll_wait
);
3341 free_swap_address_space
:
3342 exit_swap_address_space(p
->type
);
3343 bad_swap_unlock_inode
:
3344 inode_unlock(inode
);
3346 free_percpu(p
->percpu_cluster
);
3347 p
->percpu_cluster
= NULL
;
3348 free_percpu(p
->cluster_next_cpu
);
3349 p
->cluster_next_cpu
= NULL
;
3350 if (inode
&& S_ISBLK(inode
->i_mode
) && p
->bdev
) {
3351 set_blocksize(p
->bdev
, p
->old_block_size
);
3352 blkdev_put(p
->bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
3355 destroy_swap_extents(p
);
3356 swap_cgroup_swapoff(p
->type
);
3357 spin_lock(&swap_lock
);
3358 p
->swap_file
= NULL
;
3360 spin_unlock(&swap_lock
);
3362 kvfree(cluster_info
);
3363 kvfree(frontswap_map
);
3364 if (inced_nr_rotate_swap
)
3365 atomic_dec(&nr_rotate_swap
);
3367 filp_close(swap_file
, NULL
);
3369 if (page
&& !IS_ERR(page
)) {
3376 inode_unlock(inode
);
3378 enable_swap_slots_cache();
3382 void si_swapinfo(struct sysinfo
*val
)
3385 unsigned long nr_to_be_unused
= 0;
3387 spin_lock(&swap_lock
);
3388 for (type
= 0; type
< nr_swapfiles
; type
++) {
3389 struct swap_info_struct
*si
= swap_info
[type
];
3391 if ((si
->flags
& SWP_USED
) && !(si
->flags
& SWP_WRITEOK
))
3392 nr_to_be_unused
+= si
->inuse_pages
;
3394 val
->freeswap
= atomic_long_read(&nr_swap_pages
) + nr_to_be_unused
;
3395 val
->totalswap
= total_swap_pages
+ nr_to_be_unused
;
3396 spin_unlock(&swap_lock
);
3400 * Verify that a swap entry is valid and increment its swap map count.
3402 * Returns error code in following case.
3404 * - swp_entry is invalid -> EINVAL
3405 * - swp_entry is migration entry -> EINVAL
3406 * - swap-cache reference is requested but there is already one. -> EEXIST
3407 * - swap-cache reference is requested but the entry is not used. -> ENOENT
3408 * - swap-mapped reference requested but needs continued swap count. -> ENOMEM
3410 static int __swap_duplicate(swp_entry_t entry
, unsigned char usage
)
3412 struct swap_info_struct
*p
;
3413 struct swap_cluster_info
*ci
;
3414 unsigned long offset
;
3415 unsigned char count
;
3416 unsigned char has_cache
;
3419 p
= get_swap_device(entry
);
3423 offset
= swp_offset(entry
);
3424 ci
= lock_cluster_or_swap_info(p
, offset
);
3426 count
= p
->swap_map
[offset
];
3429 * swapin_readahead() doesn't check if a swap entry is valid, so the
3430 * swap entry could be SWAP_MAP_BAD. Check here with lock held.
3432 if (unlikely(swap_count(count
) == SWAP_MAP_BAD
)) {
3437 has_cache
= count
& SWAP_HAS_CACHE
;
3438 count
&= ~SWAP_HAS_CACHE
;
3441 if (usage
== SWAP_HAS_CACHE
) {
3443 /* set SWAP_HAS_CACHE if there is no cache and entry is used */
3444 if (!has_cache
&& count
)
3445 has_cache
= SWAP_HAS_CACHE
;
3446 else if (has_cache
) /* someone else added cache */
3448 else /* no users remaining */
3451 } else if (count
|| has_cache
) {
3453 if ((count
& ~COUNT_CONTINUED
) < SWAP_MAP_MAX
)
3455 else if ((count
& ~COUNT_CONTINUED
) > SWAP_MAP_MAX
)
3457 else if (swap_count_continued(p
, offset
, count
))
3458 count
= COUNT_CONTINUED
;
3462 err
= -ENOENT
; /* unused swap entry */
3464 WRITE_ONCE(p
->swap_map
[offset
], count
| has_cache
);
3467 unlock_cluster_or_swap_info(p
, ci
);
3474 * Help swapoff by noting that swap entry belongs to shmem/tmpfs
3475 * (in which case its reference count is never incremented).
3477 void swap_shmem_alloc(swp_entry_t entry
)
3479 __swap_duplicate(entry
, SWAP_MAP_SHMEM
);
3483 * Increase reference count of swap entry by 1.
3484 * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
3485 * but could not be atomically allocated. Returns 0, just as if it succeeded,
3486 * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
3487 * might occur if a page table entry has got corrupted.
3489 int swap_duplicate(swp_entry_t entry
)
3493 while (!err
&& __swap_duplicate(entry
, 1) == -ENOMEM
)
3494 err
= add_swap_count_continuation(entry
, GFP_ATOMIC
);
3499 * @entry: swap entry for which we allocate swap cache.
3501 * Called when allocating swap cache for existing swap entry,
3502 * This can return error codes. Returns 0 at success.
3503 * -EEXIST means there is a swap cache.
3504 * Note: return code is different from swap_duplicate().
3506 int swapcache_prepare(swp_entry_t entry
)
3508 return __swap_duplicate(entry
, SWAP_HAS_CACHE
);
3511 struct swap_info_struct
*swp_swap_info(swp_entry_t entry
)
3513 return swap_type_to_swap_info(swp_type(entry
));
3516 struct swap_info_struct
*page_swap_info(struct page
*page
)
3518 swp_entry_t entry
= { .val
= page_private(page
) };
3519 return swp_swap_info(entry
);
3523 * out-of-line __page_file_ methods to avoid include hell.
3525 struct address_space
*__page_file_mapping(struct page
*page
)
3527 return page_swap_info(page
)->swap_file
->f_mapping
;
3529 EXPORT_SYMBOL_GPL(__page_file_mapping
);
3531 pgoff_t
__page_file_index(struct page
*page
)
3533 swp_entry_t swap
= { .val
= page_private(page
) };
3534 return swp_offset(swap
);
3536 EXPORT_SYMBOL_GPL(__page_file_index
);
3539 * add_swap_count_continuation - called when a swap count is duplicated
3540 * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
3541 * page of the original vmalloc'ed swap_map, to hold the continuation count
3542 * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called
3543 * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
3545 * These continuation pages are seldom referenced: the common paths all work
3546 * on the original swap_map, only referring to a continuation page when the
3547 * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
3549 * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
3550 * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
3551 * can be called after dropping locks.
3553 int add_swap_count_continuation(swp_entry_t entry
, gfp_t gfp_mask
)
3555 struct swap_info_struct
*si
;
3556 struct swap_cluster_info
*ci
;
3559 struct page
*list_page
;
3561 unsigned char count
;
3565 * When debugging, it's easier to use __GFP_ZERO here; but it's better
3566 * for latency not to zero a page while GFP_ATOMIC and holding locks.
3568 page
= alloc_page(gfp_mask
| __GFP_HIGHMEM
);
3570 si
= get_swap_device(entry
);
3573 * An acceptable race has occurred since the failing
3574 * __swap_duplicate(): the swap device may be swapoff
3578 spin_lock(&si
->lock
);
3580 offset
= swp_offset(entry
);
3582 ci
= lock_cluster(si
, offset
);
3584 count
= swap_count(si
->swap_map
[offset
]);
3586 if ((count
& ~COUNT_CONTINUED
) != SWAP_MAP_MAX
) {
3588 * The higher the swap count, the more likely it is that tasks
3589 * will race to add swap count continuation: we need to avoid
3590 * over-provisioning.
3601 * We are fortunate that although vmalloc_to_page uses pte_offset_map,
3602 * no architecture is using highmem pages for kernel page tables: so it
3603 * will not corrupt the GFP_ATOMIC caller's atomic page table kmaps.
3605 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3606 offset
&= ~PAGE_MASK
;
3608 spin_lock(&si
->cont_lock
);
3610 * Page allocation does not initialize the page's lru field,
3611 * but it does always reset its private field.
3613 if (!page_private(head
)) {
3614 BUG_ON(count
& COUNT_CONTINUED
);
3615 INIT_LIST_HEAD(&head
->lru
);
3616 set_page_private(head
, SWP_CONTINUED
);
3617 si
->flags
|= SWP_CONTINUED
;
3620 list_for_each_entry(list_page
, &head
->lru
, lru
) {
3624 * If the previous map said no continuation, but we've found
3625 * a continuation page, free our allocation and use this one.
3627 if (!(count
& COUNT_CONTINUED
))
3628 goto out_unlock_cont
;
3630 map
= kmap_atomic(list_page
) + offset
;
3635 * If this continuation count now has some space in it,
3636 * free our allocation and use this one.
3638 if ((count
& ~COUNT_CONTINUED
) != SWAP_CONT_MAX
)
3639 goto out_unlock_cont
;
3642 list_add_tail(&page
->lru
, &head
->lru
);
3643 page
= NULL
; /* now it's attached, don't free it */
3645 spin_unlock(&si
->cont_lock
);
3648 spin_unlock(&si
->lock
);
3649 put_swap_device(si
);
3657 * swap_count_continued - when the original swap_map count is incremented
3658 * from SWAP_MAP_MAX, check if there is already a continuation page to carry
3659 * into, carry if so, or else fail until a new continuation page is allocated;
3660 * when the original swap_map count is decremented from 0 with continuation,
3661 * borrow from the continuation and report whether it still holds more.
3662 * Called while __swap_duplicate() or swap_entry_free() holds swap or cluster
3665 static bool swap_count_continued(struct swap_info_struct
*si
,
3666 pgoff_t offset
, unsigned char count
)
3673 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3674 if (page_private(head
) != SWP_CONTINUED
) {
3675 BUG_ON(count
& COUNT_CONTINUED
);
3676 return false; /* need to add count continuation */
3679 spin_lock(&si
->cont_lock
);
3680 offset
&= ~PAGE_MASK
;
3681 page
= list_next_entry(head
, lru
);
3682 map
= kmap_atomic(page
) + offset
;
3684 if (count
== SWAP_MAP_MAX
) /* initial increment from swap_map */
3685 goto init_map
; /* jump over SWAP_CONT_MAX checks */
3687 if (count
== (SWAP_MAP_MAX
| COUNT_CONTINUED
)) { /* incrementing */
3689 * Think of how you add 1 to 999
3691 while (*map
== (SWAP_CONT_MAX
| COUNT_CONTINUED
)) {
3693 page
= list_next_entry(page
, lru
);
3694 BUG_ON(page
== head
);
3695 map
= kmap_atomic(page
) + offset
;
3697 if (*map
== SWAP_CONT_MAX
) {
3699 page
= list_next_entry(page
, lru
);
3701 ret
= false; /* add count continuation */
3704 map
= kmap_atomic(page
) + offset
;
3705 init_map
: *map
= 0; /* we didn't zero the page */
3709 while ((page
= list_prev_entry(page
, lru
)) != head
) {
3710 map
= kmap_atomic(page
) + offset
;
3711 *map
= COUNT_CONTINUED
;
3714 ret
= true; /* incremented */
3716 } else { /* decrementing */
3718 * Think of how you subtract 1 from 1000
3720 BUG_ON(count
!= COUNT_CONTINUED
);
3721 while (*map
== COUNT_CONTINUED
) {
3723 page
= list_next_entry(page
, lru
);
3724 BUG_ON(page
== head
);
3725 map
= kmap_atomic(page
) + offset
;
3732 while ((page
= list_prev_entry(page
, lru
)) != head
) {
3733 map
= kmap_atomic(page
) + offset
;
3734 *map
= SWAP_CONT_MAX
| count
;
3735 count
= COUNT_CONTINUED
;
3738 ret
= count
== COUNT_CONTINUED
;
3741 spin_unlock(&si
->cont_lock
);
3746 * free_swap_count_continuations - swapoff free all the continuation pages
3747 * appended to the swap_map, after swap_map is quiesced, before vfree'ing it.
3749 static void free_swap_count_continuations(struct swap_info_struct
*si
)
3753 for (offset
= 0; offset
< si
->max
; offset
+= PAGE_SIZE
) {
3755 head
= vmalloc_to_page(si
->swap_map
+ offset
);
3756 if (page_private(head
)) {
3757 struct page
*page
, *next
;
3759 list_for_each_entry_safe(page
, next
, &head
->lru
, lru
) {
3760 list_del(&page
->lru
);
3767 #if defined(CONFIG_MEMCG) && defined(CONFIG_BLK_CGROUP)
3768 void cgroup_throttle_swaprate(struct page
*page
, gfp_t gfp_mask
)
3770 struct swap_info_struct
*si
, *next
;
3771 int nid
= page_to_nid(page
);
3773 if (!(gfp_mask
& __GFP_IO
))
3776 if (!blk_cgroup_congested())
3780 * We've already scheduled a throttle, avoid taking the global swap
3783 if (current
->throttle_queue
)
3786 spin_lock(&swap_avail_lock
);
3787 plist_for_each_entry_safe(si
, next
, &swap_avail_heads
[nid
],
3790 blkcg_schedule_throttle(bdev_get_queue(si
->bdev
), true);
3794 spin_unlock(&swap_avail_lock
);
3798 static int __init
swapfile_init(void)
3802 swap_avail_heads
= kmalloc_array(nr_node_ids
, sizeof(struct plist_head
),
3804 if (!swap_avail_heads
) {
3805 pr_emerg("Not enough memory for swap heads, swap is disabled\n");
3810 plist_head_init(&swap_avail_heads
[nid
]);
3814 subsys_initcall(swapfile_init
);