4 * Copyright (C) 1991, 1992, 1993, 1994 Linus Torvalds
5 * Swap reorganised 29.12.95, Stephen Tweedie
9 #include <linux/hugetlb.h>
10 #include <linux/mman.h>
11 #include <linux/slab.h>
12 #include <linux/kernel_stat.h>
13 #include <linux/swap.h>
14 #include <linux/vmalloc.h>
15 #include <linux/pagemap.h>
16 #include <linux/namei.h>
17 #include <linux/shmem_fs.h>
18 #include <linux/blkdev.h>
19 #include <linux/random.h>
20 #include <linux/writeback.h>
21 #include <linux/proc_fs.h>
22 #include <linux/seq_file.h>
23 #include <linux/init.h>
24 #include <linux/ksm.h>
25 #include <linux/rmap.h>
26 #include <linux/security.h>
27 #include <linux/backing-dev.h>
28 #include <linux/mutex.h>
29 #include <linux/capability.h>
30 #include <linux/syscalls.h>
31 #include <linux/memcontrol.h>
32 #include <linux/poll.h>
33 #include <linux/oom.h>
35 #include <asm/pgtable.h>
36 #include <asm/tlbflush.h>
37 #include <linux/swapops.h>
38 #include <linux/page_cgroup.h>
40 static bool swap_count_continued(struct swap_info_struct
*, pgoff_t
,
42 static void free_swap_count_continuations(struct swap_info_struct
*);
43 static sector_t
map_swap_entry(swp_entry_t
, struct block_device
**);
45 static DEFINE_SPINLOCK(swap_lock
);
46 static unsigned int nr_swapfiles
;
48 long total_swap_pages
;
49 static int least_priority
;
51 static const char Bad_file
[] = "Bad swap file entry ";
52 static const char Unused_file
[] = "Unused swap file entry ";
53 static const char Bad_offset
[] = "Bad swap offset entry ";
54 static const char Unused_offset
[] = "Unused swap offset entry ";
56 static struct swap_list_t swap_list
= {-1, -1};
58 static struct swap_info_struct
*swap_info
[MAX_SWAPFILES
];
60 static DEFINE_MUTEX(swapon_mutex
);
62 static DECLARE_WAIT_QUEUE_HEAD(proc_poll_wait
);
63 /* Activity counter to indicate that a swapon or swapoff has occurred */
64 static atomic_t proc_poll_event
= ATOMIC_INIT(0);
66 static inline unsigned char swap_count(unsigned char ent
)
68 return ent
& ~SWAP_HAS_CACHE
; /* may include SWAP_HAS_CONT flag */
71 /* returns 1 if swap entry is freed */
73 __try_to_reclaim_swap(struct swap_info_struct
*si
, unsigned long offset
)
75 swp_entry_t entry
= swp_entry(si
->type
, offset
);
79 page
= find_get_page(&swapper_space
, entry
.val
);
83 * This function is called from scan_swap_map() and it's called
84 * by vmscan.c at reclaiming pages. So, we hold a lock on a page, here.
85 * We have to use trylock for avoiding deadlock. This is a special
86 * case and you should use try_to_free_swap() with explicit lock_page()
87 * in usual operations.
89 if (trylock_page(page
)) {
90 ret
= try_to_free_swap(page
);
93 page_cache_release(page
);
98 * swapon tell device that all the old swap contents can be discarded,
99 * to allow the swap device to optimize its wear-levelling.
101 static int discard_swap(struct swap_info_struct
*si
)
103 struct swap_extent
*se
;
104 sector_t start_block
;
108 /* Do not discard the swap header page! */
109 se
= &si
->first_swap_extent
;
110 start_block
= (se
->start_block
+ 1) << (PAGE_SHIFT
- 9);
111 nr_blocks
= ((sector_t
)se
->nr_pages
- 1) << (PAGE_SHIFT
- 9);
113 err
= blkdev_issue_discard(si
->bdev
, start_block
,
114 nr_blocks
, GFP_KERNEL
, 0);
120 list_for_each_entry(se
, &si
->first_swap_extent
.list
, list
) {
121 start_block
= se
->start_block
<< (PAGE_SHIFT
- 9);
122 nr_blocks
= (sector_t
)se
->nr_pages
<< (PAGE_SHIFT
- 9);
124 err
= blkdev_issue_discard(si
->bdev
, start_block
,
125 nr_blocks
, GFP_KERNEL
, 0);
131 return err
; /* That will often be -EOPNOTSUPP */
135 * swap allocation tell device that a cluster of swap can now be discarded,
136 * to allow the swap device to optimize its wear-levelling.
138 static void discard_swap_cluster(struct swap_info_struct
*si
,
139 pgoff_t start_page
, pgoff_t nr_pages
)
141 struct swap_extent
*se
= si
->curr_swap_extent
;
142 int found_extent
= 0;
145 struct list_head
*lh
;
147 if (se
->start_page
<= start_page
&&
148 start_page
< se
->start_page
+ se
->nr_pages
) {
149 pgoff_t offset
= start_page
- se
->start_page
;
150 sector_t start_block
= se
->start_block
+ offset
;
151 sector_t nr_blocks
= se
->nr_pages
- offset
;
153 if (nr_blocks
> nr_pages
)
154 nr_blocks
= nr_pages
;
155 start_page
+= nr_blocks
;
156 nr_pages
-= nr_blocks
;
159 si
->curr_swap_extent
= se
;
161 start_block
<<= PAGE_SHIFT
- 9;
162 nr_blocks
<<= PAGE_SHIFT
- 9;
163 if (blkdev_issue_discard(si
->bdev
, start_block
,
164 nr_blocks
, GFP_NOIO
, 0))
169 se
= list_entry(lh
, struct swap_extent
, list
);
173 static int wait_for_discard(void *word
)
179 #define SWAPFILE_CLUSTER 256
180 #define LATENCY_LIMIT 256
182 static unsigned long scan_swap_map(struct swap_info_struct
*si
,
185 unsigned long offset
;
186 unsigned long scan_base
;
187 unsigned long last_in_cluster
= 0;
188 int latency_ration
= LATENCY_LIMIT
;
189 int found_free_cluster
= 0;
192 * We try to cluster swap pages by allocating them sequentially
193 * in swap. Once we've allocated SWAPFILE_CLUSTER pages this
194 * way, however, we resort to first-free allocation, starting
195 * a new cluster. This prevents us from scattering swap pages
196 * all over the entire swap partition, so that we reduce
197 * overall disk seek times between swap pages. -- sct
198 * But we do now try to find an empty cluster. -Andrea
199 * And we let swap pages go all over an SSD partition. Hugh
202 si
->flags
+= SWP_SCANNING
;
203 scan_base
= offset
= si
->cluster_next
;
205 if (unlikely(!si
->cluster_nr
--)) {
206 if (si
->pages
- si
->inuse_pages
< SWAPFILE_CLUSTER
) {
207 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
210 if (si
->flags
& SWP_DISCARDABLE
) {
212 * Start range check on racing allocations, in case
213 * they overlap the cluster we eventually decide on
214 * (we scan without swap_lock to allow preemption).
215 * It's hardly conceivable that cluster_nr could be
216 * wrapped during our scan, but don't depend on it.
218 if (si
->lowest_alloc
)
220 si
->lowest_alloc
= si
->max
;
221 si
->highest_alloc
= 0;
223 spin_unlock(&swap_lock
);
226 * If seek is expensive, start searching for new cluster from
227 * start of partition, to minimize the span of allocated swap.
228 * But if seek is cheap, search from our current position, so
229 * that swap is allocated from all over the partition: if the
230 * Flash Translation Layer only remaps within limited zones,
231 * we don't want to wear out the first zone too quickly.
233 if (!(si
->flags
& SWP_SOLIDSTATE
))
234 scan_base
= offset
= si
->lowest_bit
;
235 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
- 1;
237 /* Locate the first empty (unaligned) cluster */
238 for (; last_in_cluster
<= si
->highest_bit
; offset
++) {
239 if (si
->swap_map
[offset
])
240 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
;
241 else if (offset
== last_in_cluster
) {
242 spin_lock(&swap_lock
);
243 offset
-= SWAPFILE_CLUSTER
- 1;
244 si
->cluster_next
= offset
;
245 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
246 found_free_cluster
= 1;
249 if (unlikely(--latency_ration
< 0)) {
251 latency_ration
= LATENCY_LIMIT
;
255 offset
= si
->lowest_bit
;
256 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
- 1;
258 /* Locate the first empty (unaligned) cluster */
259 for (; last_in_cluster
< scan_base
; offset
++) {
260 if (si
->swap_map
[offset
])
261 last_in_cluster
= offset
+ SWAPFILE_CLUSTER
;
262 else if (offset
== last_in_cluster
) {
263 spin_lock(&swap_lock
);
264 offset
-= SWAPFILE_CLUSTER
- 1;
265 si
->cluster_next
= offset
;
266 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
267 found_free_cluster
= 1;
270 if (unlikely(--latency_ration
< 0)) {
272 latency_ration
= LATENCY_LIMIT
;
277 spin_lock(&swap_lock
);
278 si
->cluster_nr
= SWAPFILE_CLUSTER
- 1;
279 si
->lowest_alloc
= 0;
283 if (!(si
->flags
& SWP_WRITEOK
))
285 if (!si
->highest_bit
)
287 if (offset
> si
->highest_bit
)
288 scan_base
= offset
= si
->lowest_bit
;
290 /* reuse swap entry of cache-only swap if not busy. */
291 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
293 spin_unlock(&swap_lock
);
294 swap_was_freed
= __try_to_reclaim_swap(si
, offset
);
295 spin_lock(&swap_lock
);
296 /* entry was freed successfully, try to use this again */
299 goto scan
; /* check next one */
302 if (si
->swap_map
[offset
])
305 if (offset
== si
->lowest_bit
)
307 if (offset
== si
->highest_bit
)
310 if (si
->inuse_pages
== si
->pages
) {
311 si
->lowest_bit
= si
->max
;
314 si
->swap_map
[offset
] = usage
;
315 si
->cluster_next
= offset
+ 1;
316 si
->flags
-= SWP_SCANNING
;
318 if (si
->lowest_alloc
) {
320 * Only set when SWP_DISCARDABLE, and there's a scan
321 * for a free cluster in progress or just completed.
323 if (found_free_cluster
) {
325 * To optimize wear-levelling, discard the
326 * old data of the cluster, taking care not to
327 * discard any of its pages that have already
328 * been allocated by racing tasks (offset has
329 * already stepped over any at the beginning).
331 if (offset
< si
->highest_alloc
&&
332 si
->lowest_alloc
<= last_in_cluster
)
333 last_in_cluster
= si
->lowest_alloc
- 1;
334 si
->flags
|= SWP_DISCARDING
;
335 spin_unlock(&swap_lock
);
337 if (offset
< last_in_cluster
)
338 discard_swap_cluster(si
, offset
,
339 last_in_cluster
- offset
+ 1);
341 spin_lock(&swap_lock
);
342 si
->lowest_alloc
= 0;
343 si
->flags
&= ~SWP_DISCARDING
;
345 smp_mb(); /* wake_up_bit advises this */
346 wake_up_bit(&si
->flags
, ilog2(SWP_DISCARDING
));
348 } else if (si
->flags
& SWP_DISCARDING
) {
350 * Delay using pages allocated by racing tasks
351 * until the whole discard has been issued. We
352 * could defer that delay until swap_writepage,
353 * but it's easier to keep this self-contained.
355 spin_unlock(&swap_lock
);
356 wait_on_bit(&si
->flags
, ilog2(SWP_DISCARDING
),
357 wait_for_discard
, TASK_UNINTERRUPTIBLE
);
358 spin_lock(&swap_lock
);
361 * Note pages allocated by racing tasks while
362 * scan for a free cluster is in progress, so
363 * that its final discard can exclude them.
365 if (offset
< si
->lowest_alloc
)
366 si
->lowest_alloc
= offset
;
367 if (offset
> si
->highest_alloc
)
368 si
->highest_alloc
= offset
;
374 spin_unlock(&swap_lock
);
375 while (++offset
<= si
->highest_bit
) {
376 if (!si
->swap_map
[offset
]) {
377 spin_lock(&swap_lock
);
380 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
381 spin_lock(&swap_lock
);
384 if (unlikely(--latency_ration
< 0)) {
386 latency_ration
= LATENCY_LIMIT
;
389 offset
= si
->lowest_bit
;
390 while (++offset
< scan_base
) {
391 if (!si
->swap_map
[offset
]) {
392 spin_lock(&swap_lock
);
395 if (vm_swap_full() && si
->swap_map
[offset
] == SWAP_HAS_CACHE
) {
396 spin_lock(&swap_lock
);
399 if (unlikely(--latency_ration
< 0)) {
401 latency_ration
= LATENCY_LIMIT
;
404 spin_lock(&swap_lock
);
407 si
->flags
-= SWP_SCANNING
;
411 swp_entry_t
get_swap_page(void)
413 struct swap_info_struct
*si
;
418 spin_lock(&swap_lock
);
419 if (nr_swap_pages
<= 0)
423 for (type
= swap_list
.next
; type
>= 0 && wrapped
< 2; type
= next
) {
424 si
= swap_info
[type
];
427 (!wrapped
&& si
->prio
!= swap_info
[next
]->prio
)) {
428 next
= swap_list
.head
;
432 if (!si
->highest_bit
)
434 if (!(si
->flags
& SWP_WRITEOK
))
437 swap_list
.next
= next
;
438 /* This is called for allocating swap entry for cache */
439 offset
= scan_swap_map(si
, SWAP_HAS_CACHE
);
441 spin_unlock(&swap_lock
);
442 return swp_entry(type
, offset
);
444 next
= swap_list
.next
;
449 spin_unlock(&swap_lock
);
450 return (swp_entry_t
) {0};
453 /* The only caller of this function is now susupend routine */
454 swp_entry_t
get_swap_page_of_type(int type
)
456 struct swap_info_struct
*si
;
459 spin_lock(&swap_lock
);
460 si
= swap_info
[type
];
461 if (si
&& (si
->flags
& SWP_WRITEOK
)) {
463 /* This is called for allocating swap entry, not cache */
464 offset
= scan_swap_map(si
, 1);
466 spin_unlock(&swap_lock
);
467 return swp_entry(type
, offset
);
471 spin_unlock(&swap_lock
);
472 return (swp_entry_t
) {0};
475 static struct swap_info_struct
*swap_info_get(swp_entry_t entry
)
477 struct swap_info_struct
*p
;
478 unsigned long offset
, type
;
482 type
= swp_type(entry
);
483 if (type
>= nr_swapfiles
)
486 if (!(p
->flags
& SWP_USED
))
488 offset
= swp_offset(entry
);
489 if (offset
>= p
->max
)
491 if (!p
->swap_map
[offset
])
493 spin_lock(&swap_lock
);
497 printk(KERN_ERR
"swap_free: %s%08lx\n", Unused_offset
, entry
.val
);
500 printk(KERN_ERR
"swap_free: %s%08lx\n", Bad_offset
, entry
.val
);
503 printk(KERN_ERR
"swap_free: %s%08lx\n", Unused_file
, entry
.val
);
506 printk(KERN_ERR
"swap_free: %s%08lx\n", Bad_file
, entry
.val
);
511 static unsigned char swap_entry_free(struct swap_info_struct
*p
,
512 swp_entry_t entry
, unsigned char usage
)
514 unsigned long offset
= swp_offset(entry
);
516 unsigned char has_cache
;
518 count
= p
->swap_map
[offset
];
519 has_cache
= count
& SWAP_HAS_CACHE
;
520 count
&= ~SWAP_HAS_CACHE
;
522 if (usage
== SWAP_HAS_CACHE
) {
523 VM_BUG_ON(!has_cache
);
525 } else if (count
== SWAP_MAP_SHMEM
) {
527 * Or we could insist on shmem.c using a special
528 * swap_shmem_free() and free_shmem_swap_and_cache()...
531 } else if ((count
& ~COUNT_CONTINUED
) <= SWAP_MAP_MAX
) {
532 if (count
== COUNT_CONTINUED
) {
533 if (swap_count_continued(p
, offset
, count
))
534 count
= SWAP_MAP_MAX
| COUNT_CONTINUED
;
536 count
= SWAP_MAP_MAX
;
542 mem_cgroup_uncharge_swap(entry
);
544 usage
= count
| has_cache
;
545 p
->swap_map
[offset
] = usage
;
547 /* free if no reference */
549 struct gendisk
*disk
= p
->bdev
->bd_disk
;
550 if (offset
< p
->lowest_bit
)
551 p
->lowest_bit
= offset
;
552 if (offset
> p
->highest_bit
)
553 p
->highest_bit
= offset
;
554 if (swap_list
.next
>= 0 &&
555 p
->prio
> swap_info
[swap_list
.next
]->prio
)
556 swap_list
.next
= p
->type
;
559 if ((p
->flags
& SWP_BLKDEV
) &&
560 disk
->fops
->swap_slot_free_notify
)
561 disk
->fops
->swap_slot_free_notify(p
->bdev
, offset
);
568 * Caller has made sure that the swapdevice corresponding to entry
569 * is still around or has not been recycled.
571 void swap_free(swp_entry_t entry
)
573 struct swap_info_struct
*p
;
575 p
= swap_info_get(entry
);
577 swap_entry_free(p
, entry
, 1);
578 spin_unlock(&swap_lock
);
583 * Called after dropping swapcache to decrease refcnt to swap entries.
585 void swapcache_free(swp_entry_t entry
, struct page
*page
)
587 struct swap_info_struct
*p
;
590 p
= swap_info_get(entry
);
592 count
= swap_entry_free(p
, entry
, SWAP_HAS_CACHE
);
594 mem_cgroup_uncharge_swapcache(page
, entry
, count
!= 0);
595 spin_unlock(&swap_lock
);
600 * How many references to page are currently swapped out?
601 * This does not give an exact answer when swap count is continued,
602 * but does include the high COUNT_CONTINUED flag to allow for that.
604 static inline int page_swapcount(struct page
*page
)
607 struct swap_info_struct
*p
;
610 entry
.val
= page_private(page
);
611 p
= swap_info_get(entry
);
613 count
= swap_count(p
->swap_map
[swp_offset(entry
)]);
614 spin_unlock(&swap_lock
);
620 * We can write to an anon page without COW if there are no other references
621 * to it. And as a side-effect, free up its swap: because the old content
622 * on disk will never be read, and seeking back there to write new content
623 * later would only waste time away from clustering.
625 int reuse_swap_page(struct page
*page
)
629 VM_BUG_ON(!PageLocked(page
));
630 if (unlikely(PageKsm(page
)))
632 count
= page_mapcount(page
);
633 if (count
<= 1 && PageSwapCache(page
)) {
634 count
+= page_swapcount(page
);
635 if (count
== 1 && !PageWriteback(page
)) {
636 delete_from_swap_cache(page
);
644 * If swap is getting full, or if there are no more mappings of this page,
645 * then try_to_free_swap is called to free its swap space.
647 int try_to_free_swap(struct page
*page
)
649 VM_BUG_ON(!PageLocked(page
));
651 if (!PageSwapCache(page
))
653 if (PageWriteback(page
))
655 if (page_swapcount(page
))
659 * Once hibernation has begun to create its image of memory,
660 * there's a danger that one of the calls to try_to_free_swap()
661 * - most probably a call from __try_to_reclaim_swap() while
662 * hibernation is allocating its own swap pages for the image,
663 * but conceivably even a call from memory reclaim - will free
664 * the swap from a page which has already been recorded in the
665 * image as a clean swapcache page, and then reuse its swap for
666 * another page of the image. On waking from hibernation, the
667 * original page might be freed under memory pressure, then
668 * later read back in from swap, now with the wrong data.
670 * Hibernation clears bits from gfp_allowed_mask to prevent
671 * memory reclaim from writing to disk, so check that here.
673 if (!(gfp_allowed_mask
& __GFP_IO
))
676 delete_from_swap_cache(page
);
682 * Free the swap entry like above, but also try to
683 * free the page cache entry if it is the last user.
685 int free_swap_and_cache(swp_entry_t entry
)
687 struct swap_info_struct
*p
;
688 struct page
*page
= NULL
;
690 if (non_swap_entry(entry
))
693 p
= swap_info_get(entry
);
695 if (swap_entry_free(p
, entry
, 1) == SWAP_HAS_CACHE
) {
696 page
= find_get_page(&swapper_space
, entry
.val
);
697 if (page
&& !trylock_page(page
)) {
698 page_cache_release(page
);
702 spin_unlock(&swap_lock
);
706 * Not mapped elsewhere, or swap space full? Free it!
707 * Also recheck PageSwapCache now page is locked (above).
709 if (PageSwapCache(page
) && !PageWriteback(page
) &&
710 (!page_mapped(page
) || vm_swap_full())) {
711 delete_from_swap_cache(page
);
715 page_cache_release(page
);
720 #ifdef CONFIG_CGROUP_MEM_RES_CTLR
722 * mem_cgroup_count_swap_user - count the user of a swap entry
723 * @ent: the swap entry to be checked
724 * @pagep: the pointer for the swap cache page of the entry to be stored
726 * Returns the number of the user of the swap entry. The number is valid only
727 * for swaps of anonymous pages.
728 * If the entry is found on swap cache, the page is stored to pagep with
729 * refcount of it being incremented.
731 int mem_cgroup_count_swap_user(swp_entry_t ent
, struct page
**pagep
)
734 struct swap_info_struct
*p
;
737 page
= find_get_page(&swapper_space
, ent
.val
);
739 count
+= page_mapcount(page
);
740 p
= swap_info_get(ent
);
742 count
+= swap_count(p
->swap_map
[swp_offset(ent
)]);
743 spin_unlock(&swap_lock
);
751 #ifdef CONFIG_HIBERNATION
753 * Find the swap type that corresponds to given device (if any).
755 * @offset - number of the PAGE_SIZE-sized block of the device, starting
756 * from 0, in which the swap header is expected to be located.
758 * This is needed for the suspend to disk (aka swsusp).
760 int swap_type_of(dev_t device
, sector_t offset
, struct block_device
**bdev_p
)
762 struct block_device
*bdev
= NULL
;
766 bdev
= bdget(device
);
768 spin_lock(&swap_lock
);
769 for (type
= 0; type
< nr_swapfiles
; type
++) {
770 struct swap_info_struct
*sis
= swap_info
[type
];
772 if (!(sis
->flags
& SWP_WRITEOK
))
777 *bdev_p
= bdgrab(sis
->bdev
);
779 spin_unlock(&swap_lock
);
782 if (bdev
== sis
->bdev
) {
783 struct swap_extent
*se
= &sis
->first_swap_extent
;
785 if (se
->start_block
== offset
) {
787 *bdev_p
= bdgrab(sis
->bdev
);
789 spin_unlock(&swap_lock
);
795 spin_unlock(&swap_lock
);
803 * Get the (PAGE_SIZE) block corresponding to given offset on the swapdev
804 * corresponding to given index in swap_info (swap type).
806 sector_t
swapdev_block(int type
, pgoff_t offset
)
808 struct block_device
*bdev
;
810 if ((unsigned int)type
>= nr_swapfiles
)
812 if (!(swap_info
[type
]->flags
& SWP_WRITEOK
))
814 return map_swap_entry(swp_entry(type
, offset
), &bdev
);
818 * Return either the total number of swap pages of given type, or the number
819 * of free pages of that type (depending on @free)
821 * This is needed for software suspend
823 unsigned int count_swap_pages(int type
, int free
)
827 spin_lock(&swap_lock
);
828 if ((unsigned int)type
< nr_swapfiles
) {
829 struct swap_info_struct
*sis
= swap_info
[type
];
831 if (sis
->flags
& SWP_WRITEOK
) {
834 n
-= sis
->inuse_pages
;
837 spin_unlock(&swap_lock
);
840 #endif /* CONFIG_HIBERNATION */
843 * No need to decide whether this PTE shares the swap entry with others,
844 * just let do_wp_page work it out if a write is requested later - to
845 * force COW, vm_page_prot omits write permission from any private vma.
847 static int unuse_pte(struct vm_area_struct
*vma
, pmd_t
*pmd
,
848 unsigned long addr
, swp_entry_t entry
, struct page
*page
)
850 struct mem_cgroup
*ptr
;
855 if (mem_cgroup_try_charge_swapin(vma
->vm_mm
, page
, GFP_KERNEL
, &ptr
)) {
860 pte
= pte_offset_map_lock(vma
->vm_mm
, pmd
, addr
, &ptl
);
861 if (unlikely(!pte_same(*pte
, swp_entry_to_pte(entry
)))) {
863 mem_cgroup_cancel_charge_swapin(ptr
);
868 dec_mm_counter(vma
->vm_mm
, MM_SWAPENTS
);
869 inc_mm_counter(vma
->vm_mm
, MM_ANONPAGES
);
871 set_pte_at(vma
->vm_mm
, addr
, pte
,
872 pte_mkold(mk_pte(page
, vma
->vm_page_prot
)));
873 page_add_anon_rmap(page
, vma
, addr
);
874 mem_cgroup_commit_charge_swapin(page
, ptr
);
877 * Move the page to the active list so it is not
878 * immediately swapped out again after swapon.
882 pte_unmap_unlock(pte
, ptl
);
887 static int unuse_pte_range(struct vm_area_struct
*vma
, pmd_t
*pmd
,
888 unsigned long addr
, unsigned long end
,
889 swp_entry_t entry
, struct page
*page
)
891 pte_t swp_pte
= swp_entry_to_pte(entry
);
896 * We don't actually need pte lock while scanning for swp_pte: since
897 * we hold page lock and mmap_sem, swp_pte cannot be inserted into the
898 * page table while we're scanning; though it could get zapped, and on
899 * some architectures (e.g. x86_32 with PAE) we might catch a glimpse
900 * of unmatched parts which look like swp_pte, so unuse_pte must
901 * recheck under pte lock. Scanning without pte lock lets it be
902 * preemptible whenever CONFIG_PREEMPT but not CONFIG_HIGHPTE.
904 pte
= pte_offset_map(pmd
, addr
);
907 * swapoff spends a _lot_ of time in this loop!
908 * Test inline before going to call unuse_pte.
910 if (unlikely(pte_same(*pte
, swp_pte
))) {
912 ret
= unuse_pte(vma
, pmd
, addr
, entry
, page
);
915 pte
= pte_offset_map(pmd
, addr
);
917 } while (pte
++, addr
+= PAGE_SIZE
, addr
!= end
);
923 static inline int unuse_pmd_range(struct vm_area_struct
*vma
, pud_t
*pud
,
924 unsigned long addr
, unsigned long end
,
925 swp_entry_t entry
, struct page
*page
)
931 pmd
= pmd_offset(pud
, addr
);
933 next
= pmd_addr_end(addr
, end
);
934 if (unlikely(pmd_trans_huge(*pmd
)))
936 if (pmd_none_or_clear_bad(pmd
))
938 ret
= unuse_pte_range(vma
, pmd
, addr
, next
, entry
, page
);
941 } while (pmd
++, addr
= next
, addr
!= end
);
945 static inline int unuse_pud_range(struct vm_area_struct
*vma
, pgd_t
*pgd
,
946 unsigned long addr
, unsigned long end
,
947 swp_entry_t entry
, struct page
*page
)
953 pud
= pud_offset(pgd
, addr
);
955 next
= pud_addr_end(addr
, end
);
956 if (pud_none_or_clear_bad(pud
))
958 ret
= unuse_pmd_range(vma
, pud
, addr
, next
, entry
, page
);
961 } while (pud
++, addr
= next
, addr
!= end
);
965 static int unuse_vma(struct vm_area_struct
*vma
,
966 swp_entry_t entry
, struct page
*page
)
969 unsigned long addr
, end
, next
;
972 if (page_anon_vma(page
)) {
973 addr
= page_address_in_vma(page
, vma
);
977 end
= addr
+ PAGE_SIZE
;
979 addr
= vma
->vm_start
;
983 pgd
= pgd_offset(vma
->vm_mm
, addr
);
985 next
= pgd_addr_end(addr
, end
);
986 if (pgd_none_or_clear_bad(pgd
))
988 ret
= unuse_pud_range(vma
, pgd
, addr
, next
, entry
, page
);
991 } while (pgd
++, addr
= next
, addr
!= end
);
995 static int unuse_mm(struct mm_struct
*mm
,
996 swp_entry_t entry
, struct page
*page
)
998 struct vm_area_struct
*vma
;
1001 if (!down_read_trylock(&mm
->mmap_sem
)) {
1003 * Activate page so shrink_inactive_list is unlikely to unmap
1004 * its ptes while lock is dropped, so swapoff can make progress.
1006 activate_page(page
);
1008 down_read(&mm
->mmap_sem
);
1011 for (vma
= mm
->mmap
; vma
; vma
= vma
->vm_next
) {
1012 if (vma
->anon_vma
&& (ret
= unuse_vma(vma
, entry
, page
)))
1015 up_read(&mm
->mmap_sem
);
1016 return (ret
< 0)? ret
: 0;
1020 * Scan swap_map from current position to next entry still in use.
1021 * Recycle to start on reaching the end, returning 0 when empty.
1023 static unsigned int find_next_to_unuse(struct swap_info_struct
*si
,
1026 unsigned int max
= si
->max
;
1027 unsigned int i
= prev
;
1028 unsigned char count
;
1031 * No need for swap_lock here: we're just looking
1032 * for whether an entry is in use, not modifying it; false
1033 * hits are okay, and sys_swapoff() has already prevented new
1034 * allocations from this area (while holding swap_lock).
1043 * No entries in use at top of swap_map,
1044 * loop back to start and recheck there.
1050 count
= si
->swap_map
[i
];
1051 if (count
&& swap_count(count
) != SWAP_MAP_BAD
)
1058 * We completely avoid races by reading each swap page in advance,
1059 * and then search for the process using it. All the necessary
1060 * page table adjustments can then be made atomically.
1062 static int try_to_unuse(unsigned int type
)
1064 struct swap_info_struct
*si
= swap_info
[type
];
1065 struct mm_struct
*start_mm
;
1066 unsigned char *swap_map
;
1067 unsigned char swcount
;
1074 * When searching mms for an entry, a good strategy is to
1075 * start at the first mm we freed the previous entry from
1076 * (though actually we don't notice whether we or coincidence
1077 * freed the entry). Initialize this start_mm with a hold.
1079 * A simpler strategy would be to start at the last mm we
1080 * freed the previous entry from; but that would take less
1081 * advantage of mmlist ordering, which clusters forked mms
1082 * together, child after parent. If we race with dup_mmap(), we
1083 * prefer to resolve parent before child, lest we miss entries
1084 * duplicated after we scanned child: using last mm would invert
1087 start_mm
= &init_mm
;
1088 atomic_inc(&init_mm
.mm_users
);
1091 * Keep on scanning until all entries have gone. Usually,
1092 * one pass through swap_map is enough, but not necessarily:
1093 * there are races when an instance of an entry might be missed.
1095 while ((i
= find_next_to_unuse(si
, i
)) != 0) {
1096 if (signal_pending(current
)) {
1102 * Get a page for the entry, using the existing swap
1103 * cache page if there is one. Otherwise, get a clean
1104 * page and read the swap into it.
1106 swap_map
= &si
->swap_map
[i
];
1107 entry
= swp_entry(type
, i
);
1108 page
= read_swap_cache_async(entry
,
1109 GFP_HIGHUSER_MOVABLE
, NULL
, 0);
1112 * Either swap_duplicate() failed because entry
1113 * has been freed independently, and will not be
1114 * reused since sys_swapoff() already disabled
1115 * allocation from here, or alloc_page() failed.
1124 * Don't hold on to start_mm if it looks like exiting.
1126 if (atomic_read(&start_mm
->mm_users
) == 1) {
1128 start_mm
= &init_mm
;
1129 atomic_inc(&init_mm
.mm_users
);
1133 * Wait for and lock page. When do_swap_page races with
1134 * try_to_unuse, do_swap_page can handle the fault much
1135 * faster than try_to_unuse can locate the entry. This
1136 * apparently redundant "wait_on_page_locked" lets try_to_unuse
1137 * defer to do_swap_page in such a case - in some tests,
1138 * do_swap_page and try_to_unuse repeatedly compete.
1140 wait_on_page_locked(page
);
1141 wait_on_page_writeback(page
);
1143 wait_on_page_writeback(page
);
1146 * Remove all references to entry.
1148 swcount
= *swap_map
;
1149 if (swap_count(swcount
) == SWAP_MAP_SHMEM
) {
1150 retval
= shmem_unuse(entry
, page
);
1151 /* page has already been unlocked and released */
1156 if (swap_count(swcount
) && start_mm
!= &init_mm
)
1157 retval
= unuse_mm(start_mm
, entry
, page
);
1159 if (swap_count(*swap_map
)) {
1160 int set_start_mm
= (*swap_map
>= swcount
);
1161 struct list_head
*p
= &start_mm
->mmlist
;
1162 struct mm_struct
*new_start_mm
= start_mm
;
1163 struct mm_struct
*prev_mm
= start_mm
;
1164 struct mm_struct
*mm
;
1166 atomic_inc(&new_start_mm
->mm_users
);
1167 atomic_inc(&prev_mm
->mm_users
);
1168 spin_lock(&mmlist_lock
);
1169 while (swap_count(*swap_map
) && !retval
&&
1170 (p
= p
->next
) != &start_mm
->mmlist
) {
1171 mm
= list_entry(p
, struct mm_struct
, mmlist
);
1172 if (!atomic_inc_not_zero(&mm
->mm_users
))
1174 spin_unlock(&mmlist_lock
);
1180 swcount
= *swap_map
;
1181 if (!swap_count(swcount
)) /* any usage ? */
1183 else if (mm
== &init_mm
)
1186 retval
= unuse_mm(mm
, entry
, page
);
1188 if (set_start_mm
&& *swap_map
< swcount
) {
1189 mmput(new_start_mm
);
1190 atomic_inc(&mm
->mm_users
);
1194 spin_lock(&mmlist_lock
);
1196 spin_unlock(&mmlist_lock
);
1199 start_mm
= new_start_mm
;
1203 page_cache_release(page
);
1208 * If a reference remains (rare), we would like to leave
1209 * the page in the swap cache; but try_to_unmap could
1210 * then re-duplicate the entry once we drop page lock,
1211 * so we might loop indefinitely; also, that page could
1212 * not be swapped out to other storage meanwhile. So:
1213 * delete from cache even if there's another reference,
1214 * after ensuring that the data has been saved to disk -
1215 * since if the reference remains (rarer), it will be
1216 * read from disk into another page. Splitting into two
1217 * pages would be incorrect if swap supported "shared
1218 * private" pages, but they are handled by tmpfs files.
1220 * Given how unuse_vma() targets one particular offset
1221 * in an anon_vma, once the anon_vma has been determined,
1222 * this splitting happens to be just what is needed to
1223 * handle where KSM pages have been swapped out: re-reading
1224 * is unnecessarily slow, but we can fix that later on.
1226 if (swap_count(*swap_map
) &&
1227 PageDirty(page
) && PageSwapCache(page
)) {
1228 struct writeback_control wbc
= {
1229 .sync_mode
= WB_SYNC_NONE
,
1232 swap_writepage(page
, &wbc
);
1234 wait_on_page_writeback(page
);
1238 * It is conceivable that a racing task removed this page from
1239 * swap cache just before we acquired the page lock at the top,
1240 * or while we dropped it in unuse_mm(). The page might even
1241 * be back in swap cache on another swap area: that we must not
1242 * delete, since it may not have been written out to swap yet.
1244 if (PageSwapCache(page
) &&
1245 likely(page_private(page
) == entry
.val
))
1246 delete_from_swap_cache(page
);
1249 * So we could skip searching mms once swap count went
1250 * to 1, we did not mark any present ptes as dirty: must
1251 * mark page dirty so shrink_page_list will preserve it.
1255 page_cache_release(page
);
1258 * Make sure that we aren't completely killing
1259 * interactive performance.
1269 * After a successful try_to_unuse, if no swap is now in use, we know
1270 * we can empty the mmlist. swap_lock must be held on entry and exit.
1271 * Note that mmlist_lock nests inside swap_lock, and an mm must be
1272 * added to the mmlist just after page_duplicate - before would be racy.
1274 static void drain_mmlist(void)
1276 struct list_head
*p
, *next
;
1279 for (type
= 0; type
< nr_swapfiles
; type
++)
1280 if (swap_info
[type
]->inuse_pages
)
1282 spin_lock(&mmlist_lock
);
1283 list_for_each_safe(p
, next
, &init_mm
.mmlist
)
1285 spin_unlock(&mmlist_lock
);
1289 * Use this swapdev's extent info to locate the (PAGE_SIZE) block which
1290 * corresponds to page offset for the specified swap entry.
1291 * Note that the type of this function is sector_t, but it returns page offset
1292 * into the bdev, not sector offset.
1294 static sector_t
map_swap_entry(swp_entry_t entry
, struct block_device
**bdev
)
1296 struct swap_info_struct
*sis
;
1297 struct swap_extent
*start_se
;
1298 struct swap_extent
*se
;
1301 sis
= swap_info
[swp_type(entry
)];
1304 offset
= swp_offset(entry
);
1305 start_se
= sis
->curr_swap_extent
;
1309 struct list_head
*lh
;
1311 if (se
->start_page
<= offset
&&
1312 offset
< (se
->start_page
+ se
->nr_pages
)) {
1313 return se
->start_block
+ (offset
- se
->start_page
);
1316 se
= list_entry(lh
, struct swap_extent
, list
);
1317 sis
->curr_swap_extent
= se
;
1318 BUG_ON(se
== start_se
); /* It *must* be present */
1323 * Returns the page offset into bdev for the specified page's swap entry.
1325 sector_t
map_swap_page(struct page
*page
, struct block_device
**bdev
)
1328 entry
.val
= page_private(page
);
1329 return map_swap_entry(entry
, bdev
);
1333 * Free all of a swapdev's extent information
1335 static void destroy_swap_extents(struct swap_info_struct
*sis
)
1337 while (!list_empty(&sis
->first_swap_extent
.list
)) {
1338 struct swap_extent
*se
;
1340 se
= list_entry(sis
->first_swap_extent
.list
.next
,
1341 struct swap_extent
, list
);
1342 list_del(&se
->list
);
1348 * Add a block range (and the corresponding page range) into this swapdev's
1349 * extent list. The extent list is kept sorted in page order.
1351 * This function rather assumes that it is called in ascending page order.
1354 add_swap_extent(struct swap_info_struct
*sis
, unsigned long start_page
,
1355 unsigned long nr_pages
, sector_t start_block
)
1357 struct swap_extent
*se
;
1358 struct swap_extent
*new_se
;
1359 struct list_head
*lh
;
1361 if (start_page
== 0) {
1362 se
= &sis
->first_swap_extent
;
1363 sis
->curr_swap_extent
= se
;
1365 se
->nr_pages
= nr_pages
;
1366 se
->start_block
= start_block
;
1369 lh
= sis
->first_swap_extent
.list
.prev
; /* Highest extent */
1370 se
= list_entry(lh
, struct swap_extent
, list
);
1371 BUG_ON(se
->start_page
+ se
->nr_pages
!= start_page
);
1372 if (se
->start_block
+ se
->nr_pages
== start_block
) {
1374 se
->nr_pages
+= nr_pages
;
1380 * No merge. Insert a new extent, preserving ordering.
1382 new_se
= kmalloc(sizeof(*se
), GFP_KERNEL
);
1385 new_se
->start_page
= start_page
;
1386 new_se
->nr_pages
= nr_pages
;
1387 new_se
->start_block
= start_block
;
1389 list_add_tail(&new_se
->list
, &sis
->first_swap_extent
.list
);
1394 * A `swap extent' is a simple thing which maps a contiguous range of pages
1395 * onto a contiguous range of disk blocks. An ordered list of swap extents
1396 * is built at swapon time and is then used at swap_writepage/swap_readpage
1397 * time for locating where on disk a page belongs.
1399 * If the swapfile is an S_ISBLK block device, a single extent is installed.
1400 * This is done so that the main operating code can treat S_ISBLK and S_ISREG
1401 * swap files identically.
1403 * Whether the swapdev is an S_ISREG file or an S_ISBLK blockdev, the swap
1404 * extent list operates in PAGE_SIZE disk blocks. Both S_ISREG and S_ISBLK
1405 * swapfiles are handled *identically* after swapon time.
1407 * For S_ISREG swapfiles, setup_swap_extents() will walk all the file's blocks
1408 * and will parse them into an ordered extent list, in PAGE_SIZE chunks. If
1409 * some stray blocks are found which do not fall within the PAGE_SIZE alignment
1410 * requirements, they are simply tossed out - we will never use those blocks
1413 * For S_ISREG swapfiles we set S_SWAPFILE across the life of the swapon. This
1414 * prevents root from shooting her foot off by ftruncating an in-use swapfile,
1415 * which will scribble on the fs.
1417 * The amount of disk space which a single swap extent represents varies.
1418 * Typically it is in the 1-4 megabyte range. So we can have hundreds of
1419 * extents in the list. To avoid much list walking, we cache the previous
1420 * search location in `curr_swap_extent', and start new searches from there.
1421 * This is extremely effective. The average number of iterations in
1422 * map_swap_page() has been measured at about 0.3 per page. - akpm.
1424 static int setup_swap_extents(struct swap_info_struct
*sis
, sector_t
*span
)
1426 struct inode
*inode
;
1427 unsigned blocks_per_page
;
1428 unsigned long page_no
;
1430 sector_t probe_block
;
1431 sector_t last_block
;
1432 sector_t lowest_block
= -1;
1433 sector_t highest_block
= 0;
1437 inode
= sis
->swap_file
->f_mapping
->host
;
1438 if (S_ISBLK(inode
->i_mode
)) {
1439 ret
= add_swap_extent(sis
, 0, sis
->max
, 0);
1444 blkbits
= inode
->i_blkbits
;
1445 blocks_per_page
= PAGE_SIZE
>> blkbits
;
1448 * Map all the blocks into the extent list. This code doesn't try
1453 last_block
= i_size_read(inode
) >> blkbits
;
1454 while ((probe_block
+ blocks_per_page
) <= last_block
&&
1455 page_no
< sis
->max
) {
1456 unsigned block_in_page
;
1457 sector_t first_block
;
1459 first_block
= bmap(inode
, probe_block
);
1460 if (first_block
== 0)
1464 * It must be PAGE_SIZE aligned on-disk
1466 if (first_block
& (blocks_per_page
- 1)) {
1471 for (block_in_page
= 1; block_in_page
< blocks_per_page
;
1475 block
= bmap(inode
, probe_block
+ block_in_page
);
1478 if (block
!= first_block
+ block_in_page
) {
1485 first_block
>>= (PAGE_SHIFT
- blkbits
);
1486 if (page_no
) { /* exclude the header page */
1487 if (first_block
< lowest_block
)
1488 lowest_block
= first_block
;
1489 if (first_block
> highest_block
)
1490 highest_block
= first_block
;
1494 * We found a PAGE_SIZE-length, PAGE_SIZE-aligned run of blocks
1496 ret
= add_swap_extent(sis
, page_no
, 1, first_block
);
1501 probe_block
+= blocks_per_page
;
1506 *span
= 1 + highest_block
- lowest_block
;
1508 page_no
= 1; /* force Empty message */
1510 sis
->pages
= page_no
- 1;
1511 sis
->highest_bit
= page_no
- 1;
1515 printk(KERN_ERR
"swapon: swapfile has holes\n");
1520 static void enable_swap_info(struct swap_info_struct
*p
, int prio
,
1521 unsigned char *swap_map
)
1525 spin_lock(&swap_lock
);
1529 p
->prio
= --least_priority
;
1530 p
->swap_map
= swap_map
;
1531 p
->flags
|= SWP_WRITEOK
;
1532 nr_swap_pages
+= p
->pages
;
1533 total_swap_pages
+= p
->pages
;
1535 /* insert swap space into swap_list: */
1537 for (i
= swap_list
.head
; i
>= 0; i
= swap_info
[i
]->next
) {
1538 if (p
->prio
>= swap_info
[i
]->prio
)
1544 swap_list
.head
= swap_list
.next
= p
->type
;
1546 swap_info
[prev
]->next
= p
->type
;
1547 spin_unlock(&swap_lock
);
1550 SYSCALL_DEFINE1(swapoff
, const char __user
*, specialfile
)
1552 struct swap_info_struct
*p
= NULL
;
1553 unsigned char *swap_map
;
1554 struct file
*swap_file
, *victim
;
1555 struct address_space
*mapping
;
1556 struct inode
*inode
;
1562 if (!capable(CAP_SYS_ADMIN
))
1565 pathname
= getname(specialfile
);
1566 err
= PTR_ERR(pathname
);
1567 if (IS_ERR(pathname
))
1570 victim
= filp_open(pathname
, O_RDWR
|O_LARGEFILE
, 0);
1572 err
= PTR_ERR(victim
);
1576 mapping
= victim
->f_mapping
;
1578 spin_lock(&swap_lock
);
1579 for (type
= swap_list
.head
; type
>= 0; type
= swap_info
[type
]->next
) {
1580 p
= swap_info
[type
];
1581 if (p
->flags
& SWP_WRITEOK
) {
1582 if (p
->swap_file
->f_mapping
== mapping
)
1589 spin_unlock(&swap_lock
);
1592 if (!security_vm_enough_memory(p
->pages
))
1593 vm_unacct_memory(p
->pages
);
1596 spin_unlock(&swap_lock
);
1600 swap_list
.head
= p
->next
;
1602 swap_info
[prev
]->next
= p
->next
;
1603 if (type
== swap_list
.next
) {
1604 /* just pick something that's safe... */
1605 swap_list
.next
= swap_list
.head
;
1608 for (i
= p
->next
; i
>= 0; i
= swap_info
[i
]->next
)
1609 swap_info
[i
]->prio
= p
->prio
--;
1612 nr_swap_pages
-= p
->pages
;
1613 total_swap_pages
-= p
->pages
;
1614 p
->flags
&= ~SWP_WRITEOK
;
1615 spin_unlock(&swap_lock
);
1617 oom_score_adj
= test_set_oom_score_adj(OOM_SCORE_ADJ_MAX
);
1618 err
= try_to_unuse(type
);
1619 test_set_oom_score_adj(oom_score_adj
);
1623 * reading p->prio and p->swap_map outside the lock is
1624 * safe here because only sys_swapon and sys_swapoff
1625 * change them, and there can be no other sys_swapon or
1626 * sys_swapoff for this swap_info_struct at this point.
1628 /* re-insert swap space back into swap_list */
1629 enable_swap_info(p
, p
->prio
, p
->swap_map
);
1633 destroy_swap_extents(p
);
1634 if (p
->flags
& SWP_CONTINUED
)
1635 free_swap_count_continuations(p
);
1637 mutex_lock(&swapon_mutex
);
1638 spin_lock(&swap_lock
);
1641 /* wait for anyone still in scan_swap_map */
1642 p
->highest_bit
= 0; /* cuts scans short */
1643 while (p
->flags
>= SWP_SCANNING
) {
1644 spin_unlock(&swap_lock
);
1645 schedule_timeout_uninterruptible(1);
1646 spin_lock(&swap_lock
);
1649 swap_file
= p
->swap_file
;
1650 p
->swap_file
= NULL
;
1652 swap_map
= p
->swap_map
;
1655 spin_unlock(&swap_lock
);
1656 mutex_unlock(&swapon_mutex
);
1658 /* Destroy swap account informatin */
1659 swap_cgroup_swapoff(type
);
1661 inode
= mapping
->host
;
1662 if (S_ISBLK(inode
->i_mode
)) {
1663 struct block_device
*bdev
= I_BDEV(inode
);
1664 set_blocksize(bdev
, p
->old_block_size
);
1665 blkdev_put(bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
1667 mutex_lock(&inode
->i_mutex
);
1668 inode
->i_flags
&= ~S_SWAPFILE
;
1669 mutex_unlock(&inode
->i_mutex
);
1671 filp_close(swap_file
, NULL
);
1673 atomic_inc(&proc_poll_event
);
1674 wake_up_interruptible(&proc_poll_wait
);
1677 filp_close(victim
, NULL
);
1682 #ifdef CONFIG_PROC_FS
1683 static unsigned swaps_poll(struct file
*file
, poll_table
*wait
)
1685 struct seq_file
*seq
= file
->private_data
;
1687 poll_wait(file
, &proc_poll_wait
, wait
);
1689 if (seq
->poll_event
!= atomic_read(&proc_poll_event
)) {
1690 seq
->poll_event
= atomic_read(&proc_poll_event
);
1691 return POLLIN
| POLLRDNORM
| POLLERR
| POLLPRI
;
1694 return POLLIN
| POLLRDNORM
;
1698 static void *swap_start(struct seq_file
*swap
, loff_t
*pos
)
1700 struct swap_info_struct
*si
;
1704 mutex_lock(&swapon_mutex
);
1707 return SEQ_START_TOKEN
;
1709 for (type
= 0; type
< nr_swapfiles
; type
++) {
1710 smp_rmb(); /* read nr_swapfiles before swap_info[type] */
1711 si
= swap_info
[type
];
1712 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
1721 static void *swap_next(struct seq_file
*swap
, void *v
, loff_t
*pos
)
1723 struct swap_info_struct
*si
= v
;
1726 if (v
== SEQ_START_TOKEN
)
1729 type
= si
->type
+ 1;
1731 for (; type
< nr_swapfiles
; type
++) {
1732 smp_rmb(); /* read nr_swapfiles before swap_info[type] */
1733 si
= swap_info
[type
];
1734 if (!(si
->flags
& SWP_USED
) || !si
->swap_map
)
1743 static void swap_stop(struct seq_file
*swap
, void *v
)
1745 mutex_unlock(&swapon_mutex
);
1748 static int swap_show(struct seq_file
*swap
, void *v
)
1750 struct swap_info_struct
*si
= v
;
1754 if (si
== SEQ_START_TOKEN
) {
1755 seq_puts(swap
,"Filename\t\t\t\tType\t\tSize\tUsed\tPriority\n");
1759 file
= si
->swap_file
;
1760 len
= seq_path(swap
, &file
->f_path
, " \t\n\\");
1761 seq_printf(swap
, "%*s%s\t%u\t%u\t%d\n",
1762 len
< 40 ? 40 - len
: 1, " ",
1763 S_ISBLK(file
->f_path
.dentry
->d_inode
->i_mode
) ?
1764 "partition" : "file\t",
1765 si
->pages
<< (PAGE_SHIFT
- 10),
1766 si
->inuse_pages
<< (PAGE_SHIFT
- 10),
1771 static const struct seq_operations swaps_op
= {
1772 .start
= swap_start
,
1778 static int swaps_open(struct inode
*inode
, struct file
*file
)
1780 struct seq_file
*seq
;
1783 ret
= seq_open(file
, &swaps_op
);
1787 seq
= file
->private_data
;
1788 seq
->poll_event
= atomic_read(&proc_poll_event
);
1792 static const struct file_operations proc_swaps_operations
= {
1795 .llseek
= seq_lseek
,
1796 .release
= seq_release
,
1800 static int __init
procswaps_init(void)
1802 proc_create("swaps", 0, NULL
, &proc_swaps_operations
);
1805 __initcall(procswaps_init
);
1806 #endif /* CONFIG_PROC_FS */
1808 #ifdef MAX_SWAPFILES_CHECK
1809 static int __init
max_swapfiles_check(void)
1811 MAX_SWAPFILES_CHECK();
1814 late_initcall(max_swapfiles_check
);
1817 static struct swap_info_struct
*alloc_swap_info(void)
1819 struct swap_info_struct
*p
;
1822 p
= kzalloc(sizeof(*p
), GFP_KERNEL
);
1824 return ERR_PTR(-ENOMEM
);
1826 spin_lock(&swap_lock
);
1827 for (type
= 0; type
< nr_swapfiles
; type
++) {
1828 if (!(swap_info
[type
]->flags
& SWP_USED
))
1831 if (type
>= MAX_SWAPFILES
) {
1832 spin_unlock(&swap_lock
);
1834 return ERR_PTR(-EPERM
);
1836 if (type
>= nr_swapfiles
) {
1838 swap_info
[type
] = p
;
1840 * Write swap_info[type] before nr_swapfiles, in case a
1841 * racing procfs swap_start() or swap_next() is reading them.
1842 * (We never shrink nr_swapfiles, we never free this entry.)
1848 p
= swap_info
[type
];
1850 * Do not memset this entry: a racing procfs swap_next()
1851 * would be relying on p->type to remain valid.
1854 INIT_LIST_HEAD(&p
->first_swap_extent
.list
);
1855 p
->flags
= SWP_USED
;
1857 spin_unlock(&swap_lock
);
1862 static int claim_swapfile(struct swap_info_struct
*p
, struct inode
*inode
)
1866 if (S_ISBLK(inode
->i_mode
)) {
1867 p
->bdev
= bdgrab(I_BDEV(inode
));
1868 error
= blkdev_get(p
->bdev
,
1869 FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
,
1875 p
->old_block_size
= block_size(p
->bdev
);
1876 error
= set_blocksize(p
->bdev
, PAGE_SIZE
);
1879 p
->flags
|= SWP_BLKDEV
;
1880 } else if (S_ISREG(inode
->i_mode
)) {
1881 p
->bdev
= inode
->i_sb
->s_bdev
;
1882 mutex_lock(&inode
->i_mutex
);
1883 if (IS_SWAPFILE(inode
))
1891 static unsigned long read_swap_header(struct swap_info_struct
*p
,
1892 union swap_header
*swap_header
,
1893 struct inode
*inode
)
1896 unsigned long maxpages
;
1897 unsigned long swapfilepages
;
1899 if (memcmp("SWAPSPACE2", swap_header
->magic
.magic
, 10)) {
1900 printk(KERN_ERR
"Unable to find swap-space signature\n");
1904 /* swap partition endianess hack... */
1905 if (swab32(swap_header
->info
.version
) == 1) {
1906 swab32s(&swap_header
->info
.version
);
1907 swab32s(&swap_header
->info
.last_page
);
1908 swab32s(&swap_header
->info
.nr_badpages
);
1909 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++)
1910 swab32s(&swap_header
->info
.badpages
[i
]);
1912 /* Check the swap header's sub-version */
1913 if (swap_header
->info
.version
!= 1) {
1915 "Unable to handle swap header version %d\n",
1916 swap_header
->info
.version
);
1921 p
->cluster_next
= 1;
1925 * Find out how many pages are allowed for a single swap
1926 * device. There are three limiting factors: 1) the number
1927 * of bits for the swap offset in the swp_entry_t type, and
1928 * 2) the number of bits in the swap pte as defined by the
1929 * the different architectures, and 3) the number of free bits
1930 * in an exceptional radix_tree entry. In order to find the
1931 * largest possible bit mask, a swap entry with swap type 0
1932 * and swap offset ~0UL is created, encoded to a swap pte,
1933 * decoded to a swp_entry_t again, and finally the swap
1934 * offset is extracted. This will mask all the bits from
1935 * the initial ~0UL mask that can't be encoded in either
1936 * the swp_entry_t or the architecture definition of a
1937 * swap pte. Then the same is done for a radix_tree entry.
1939 maxpages
= swp_offset(pte_to_swp_entry(
1940 swp_entry_to_pte(swp_entry(0, ~0UL))));
1941 maxpages
= swp_offset(radix_to_swp_entry(
1942 swp_to_radix_entry(swp_entry(0, maxpages
)))) + 1;
1944 if (maxpages
> swap_header
->info
.last_page
) {
1945 maxpages
= swap_header
->info
.last_page
+ 1;
1946 /* p->max is an unsigned int: don't overflow it */
1947 if ((unsigned int)maxpages
== 0)
1948 maxpages
= UINT_MAX
;
1950 p
->highest_bit
= maxpages
- 1;
1954 swapfilepages
= i_size_read(inode
) >> PAGE_SHIFT
;
1955 if (swapfilepages
&& maxpages
> swapfilepages
) {
1957 "Swap area shorter than signature indicates\n");
1960 if (swap_header
->info
.nr_badpages
&& S_ISREG(inode
->i_mode
))
1962 if (swap_header
->info
.nr_badpages
> MAX_SWAP_BADPAGES
)
1968 static int setup_swap_map_and_extents(struct swap_info_struct
*p
,
1969 union swap_header
*swap_header
,
1970 unsigned char *swap_map
,
1971 unsigned long maxpages
,
1975 unsigned int nr_good_pages
;
1978 nr_good_pages
= maxpages
- 1; /* omit header page */
1980 for (i
= 0; i
< swap_header
->info
.nr_badpages
; i
++) {
1981 unsigned int page_nr
= swap_header
->info
.badpages
[i
];
1982 if (page_nr
== 0 || page_nr
> swap_header
->info
.last_page
)
1984 if (page_nr
< maxpages
) {
1985 swap_map
[page_nr
] = SWAP_MAP_BAD
;
1990 if (nr_good_pages
) {
1991 swap_map
[0] = SWAP_MAP_BAD
;
1993 p
->pages
= nr_good_pages
;
1994 nr_extents
= setup_swap_extents(p
, span
);
1997 nr_good_pages
= p
->pages
;
1999 if (!nr_good_pages
) {
2000 printk(KERN_WARNING
"Empty swap-file\n");
2007 SYSCALL_DEFINE2(swapon
, const char __user
*, specialfile
, int, swap_flags
)
2009 struct swap_info_struct
*p
;
2011 struct file
*swap_file
= NULL
;
2012 struct address_space
*mapping
;
2016 union swap_header
*swap_header
;
2019 unsigned long maxpages
;
2020 unsigned char *swap_map
= NULL
;
2021 struct page
*page
= NULL
;
2022 struct inode
*inode
= NULL
;
2024 if (!capable(CAP_SYS_ADMIN
))
2027 p
= alloc_swap_info();
2031 name
= getname(specialfile
);
2033 error
= PTR_ERR(name
);
2037 swap_file
= filp_open(name
, O_RDWR
|O_LARGEFILE
, 0);
2038 if (IS_ERR(swap_file
)) {
2039 error
= PTR_ERR(swap_file
);
2044 p
->swap_file
= swap_file
;
2045 mapping
= swap_file
->f_mapping
;
2047 for (i
= 0; i
< nr_swapfiles
; i
++) {
2048 struct swap_info_struct
*q
= swap_info
[i
];
2050 if (q
== p
|| !q
->swap_file
)
2052 if (mapping
== q
->swap_file
->f_mapping
) {
2058 inode
= mapping
->host
;
2059 /* If S_ISREG(inode->i_mode) will do mutex_lock(&inode->i_mutex); */
2060 error
= claim_swapfile(p
, inode
);
2061 if (unlikely(error
))
2065 * Read the swap header.
2067 if (!mapping
->a_ops
->readpage
) {
2071 page
= read_mapping_page(mapping
, 0, swap_file
);
2073 error
= PTR_ERR(page
);
2076 swap_header
= kmap(page
);
2078 maxpages
= read_swap_header(p
, swap_header
, inode
);
2079 if (unlikely(!maxpages
)) {
2084 /* OK, set up the swap map and apply the bad block list */
2085 swap_map
= vzalloc(maxpages
);
2091 error
= swap_cgroup_swapon(p
->type
, maxpages
);
2095 nr_extents
= setup_swap_map_and_extents(p
, swap_header
, swap_map
,
2097 if (unlikely(nr_extents
< 0)) {
2103 if (blk_queue_nonrot(bdev_get_queue(p
->bdev
))) {
2104 p
->flags
|= SWP_SOLIDSTATE
;
2105 p
->cluster_next
= 1 + (random32() % p
->highest_bit
);
2107 if (discard_swap(p
) == 0 && (swap_flags
& SWAP_FLAG_DISCARD
))
2108 p
->flags
|= SWP_DISCARDABLE
;
2111 mutex_lock(&swapon_mutex
);
2113 if (swap_flags
& SWAP_FLAG_PREFER
)
2115 (swap_flags
& SWAP_FLAG_PRIO_MASK
) >> SWAP_FLAG_PRIO_SHIFT
;
2116 enable_swap_info(p
, prio
, swap_map
);
2118 printk(KERN_INFO
"Adding %uk swap on %s. "
2119 "Priority:%d extents:%d across:%lluk %s%s\n",
2120 p
->pages
<<(PAGE_SHIFT
-10), name
, p
->prio
,
2121 nr_extents
, (unsigned long long)span
<<(PAGE_SHIFT
-10),
2122 (p
->flags
& SWP_SOLIDSTATE
) ? "SS" : "",
2123 (p
->flags
& SWP_DISCARDABLE
) ? "D" : "");
2125 mutex_unlock(&swapon_mutex
);
2126 atomic_inc(&proc_poll_event
);
2127 wake_up_interruptible(&proc_poll_wait
);
2129 if (S_ISREG(inode
->i_mode
))
2130 inode
->i_flags
|= S_SWAPFILE
;
2134 if (inode
&& S_ISBLK(inode
->i_mode
) && p
->bdev
) {
2135 set_blocksize(p
->bdev
, p
->old_block_size
);
2136 blkdev_put(p
->bdev
, FMODE_READ
| FMODE_WRITE
| FMODE_EXCL
);
2138 destroy_swap_extents(p
);
2139 swap_cgroup_swapoff(p
->type
);
2140 spin_lock(&swap_lock
);
2141 p
->swap_file
= NULL
;
2143 spin_unlock(&swap_lock
);
2146 if (inode
&& S_ISREG(inode
->i_mode
)) {
2147 mutex_unlock(&inode
->i_mutex
);
2150 filp_close(swap_file
, NULL
);
2153 if (page
&& !IS_ERR(page
)) {
2155 page_cache_release(page
);
2159 if (inode
&& S_ISREG(inode
->i_mode
))
2160 mutex_unlock(&inode
->i_mutex
);
2164 void si_swapinfo(struct sysinfo
*val
)
2167 unsigned long nr_to_be_unused
= 0;
2169 spin_lock(&swap_lock
);
2170 for (type
= 0; type
< nr_swapfiles
; type
++) {
2171 struct swap_info_struct
*si
= swap_info
[type
];
2173 if ((si
->flags
& SWP_USED
) && !(si
->flags
& SWP_WRITEOK
))
2174 nr_to_be_unused
+= si
->inuse_pages
;
2176 val
->freeswap
= nr_swap_pages
+ nr_to_be_unused
;
2177 val
->totalswap
= total_swap_pages
+ nr_to_be_unused
;
2178 spin_unlock(&swap_lock
);
2182 * Verify that a swap entry is valid and increment its swap map count.
2184 * Returns error code in following case.
2186 * - swp_entry is invalid -> EINVAL
2187 * - swp_entry is migration entry -> EINVAL
2188 * - swap-cache reference is requested but there is already one. -> EEXIST
2189 * - swap-cache reference is requested but the entry is not used. -> ENOENT
2190 * - swap-mapped reference requested but needs continued swap count. -> ENOMEM
2192 static int __swap_duplicate(swp_entry_t entry
, unsigned char usage
)
2194 struct swap_info_struct
*p
;
2195 unsigned long offset
, type
;
2196 unsigned char count
;
2197 unsigned char has_cache
;
2200 if (non_swap_entry(entry
))
2203 type
= swp_type(entry
);
2204 if (type
>= nr_swapfiles
)
2206 p
= swap_info
[type
];
2207 offset
= swp_offset(entry
);
2209 spin_lock(&swap_lock
);
2210 if (unlikely(offset
>= p
->max
))
2213 count
= p
->swap_map
[offset
];
2214 has_cache
= count
& SWAP_HAS_CACHE
;
2215 count
&= ~SWAP_HAS_CACHE
;
2218 if (usage
== SWAP_HAS_CACHE
) {
2220 /* set SWAP_HAS_CACHE if there is no cache and entry is used */
2221 if (!has_cache
&& count
)
2222 has_cache
= SWAP_HAS_CACHE
;
2223 else if (has_cache
) /* someone else added cache */
2225 else /* no users remaining */
2228 } else if (count
|| has_cache
) {
2230 if ((count
& ~COUNT_CONTINUED
) < SWAP_MAP_MAX
)
2232 else if ((count
& ~COUNT_CONTINUED
) > SWAP_MAP_MAX
)
2234 else if (swap_count_continued(p
, offset
, count
))
2235 count
= COUNT_CONTINUED
;
2239 err
= -ENOENT
; /* unused swap entry */
2241 p
->swap_map
[offset
] = count
| has_cache
;
2244 spin_unlock(&swap_lock
);
2249 printk(KERN_ERR
"swap_dup: %s%08lx\n", Bad_file
, entry
.val
);
2254 * Help swapoff by noting that swap entry belongs to shmem/tmpfs
2255 * (in which case its reference count is never incremented).
2257 void swap_shmem_alloc(swp_entry_t entry
)
2259 __swap_duplicate(entry
, SWAP_MAP_SHMEM
);
2263 * Increase reference count of swap entry by 1.
2264 * Returns 0 for success, or -ENOMEM if a swap_count_continuation is required
2265 * but could not be atomically allocated. Returns 0, just as if it succeeded,
2266 * if __swap_duplicate() fails for another reason (-EINVAL or -ENOENT), which
2267 * might occur if a page table entry has got corrupted.
2269 int swap_duplicate(swp_entry_t entry
)
2273 while (!err
&& __swap_duplicate(entry
, 1) == -ENOMEM
)
2274 err
= add_swap_count_continuation(entry
, GFP_ATOMIC
);
2279 * @entry: swap entry for which we allocate swap cache.
2281 * Called when allocating swap cache for existing swap entry,
2282 * This can return error codes. Returns 0 at success.
2283 * -EBUSY means there is a swap cache.
2284 * Note: return code is different from swap_duplicate().
2286 int swapcache_prepare(swp_entry_t entry
)
2288 return __swap_duplicate(entry
, SWAP_HAS_CACHE
);
2292 * swap_lock prevents swap_map being freed. Don't grab an extra
2293 * reference on the swaphandle, it doesn't matter if it becomes unused.
2295 int valid_swaphandles(swp_entry_t entry
, unsigned long *offset
)
2297 struct swap_info_struct
*si
;
2298 int our_page_cluster
= page_cluster
;
2299 pgoff_t target
, toff
;
2303 if (!our_page_cluster
) /* no readahead */
2306 si
= swap_info
[swp_type(entry
)];
2307 target
= swp_offset(entry
);
2308 base
= (target
>> our_page_cluster
) << our_page_cluster
;
2309 end
= base
+ (1 << our_page_cluster
);
2310 if (!base
) /* first page is swap header */
2313 spin_lock(&swap_lock
);
2314 if (end
> si
->max
) /* don't go beyond end of map */
2317 /* Count contiguous allocated slots above our target */
2318 for (toff
= target
; ++toff
< end
; nr_pages
++) {
2319 /* Don't read in free or bad pages */
2320 if (!si
->swap_map
[toff
])
2322 if (swap_count(si
->swap_map
[toff
]) == SWAP_MAP_BAD
)
2325 /* Count contiguous allocated slots below our target */
2326 for (toff
= target
; --toff
>= base
; nr_pages
++) {
2327 /* Don't read in free or bad pages */
2328 if (!si
->swap_map
[toff
])
2330 if (swap_count(si
->swap_map
[toff
]) == SWAP_MAP_BAD
)
2333 spin_unlock(&swap_lock
);
2336 * Indicate starting offset, and return number of pages to get:
2337 * if only 1, say 0, since there's then no readahead to be done.
2340 return nr_pages
? ++nr_pages
: 0;
2344 * add_swap_count_continuation - called when a swap count is duplicated
2345 * beyond SWAP_MAP_MAX, it allocates a new page and links that to the entry's
2346 * page of the original vmalloc'ed swap_map, to hold the continuation count
2347 * (for that entry and for its neighbouring PAGE_SIZE swap entries). Called
2348 * again when count is duplicated beyond SWAP_MAP_MAX * SWAP_CONT_MAX, etc.
2350 * These continuation pages are seldom referenced: the common paths all work
2351 * on the original swap_map, only referring to a continuation page when the
2352 * low "digit" of a count is incremented or decremented through SWAP_MAP_MAX.
2354 * add_swap_count_continuation(, GFP_ATOMIC) can be called while holding
2355 * page table locks; if it fails, add_swap_count_continuation(, GFP_KERNEL)
2356 * can be called after dropping locks.
2358 int add_swap_count_continuation(swp_entry_t entry
, gfp_t gfp_mask
)
2360 struct swap_info_struct
*si
;
2363 struct page
*list_page
;
2365 unsigned char count
;
2368 * When debugging, it's easier to use __GFP_ZERO here; but it's better
2369 * for latency not to zero a page while GFP_ATOMIC and holding locks.
2371 page
= alloc_page(gfp_mask
| __GFP_HIGHMEM
);
2373 si
= swap_info_get(entry
);
2376 * An acceptable race has occurred since the failing
2377 * __swap_duplicate(): the swap entry has been freed,
2378 * perhaps even the whole swap_map cleared for swapoff.
2383 offset
= swp_offset(entry
);
2384 count
= si
->swap_map
[offset
] & ~SWAP_HAS_CACHE
;
2386 if ((count
& ~COUNT_CONTINUED
) != SWAP_MAP_MAX
) {
2388 * The higher the swap count, the more likely it is that tasks
2389 * will race to add swap count continuation: we need to avoid
2390 * over-provisioning.
2396 spin_unlock(&swap_lock
);
2401 * We are fortunate that although vmalloc_to_page uses pte_offset_map,
2402 * no architecture is using highmem pages for kernel pagetables: so it
2403 * will not corrupt the GFP_ATOMIC caller's atomic pagetable kmaps.
2405 head
= vmalloc_to_page(si
->swap_map
+ offset
);
2406 offset
&= ~PAGE_MASK
;
2409 * Page allocation does not initialize the page's lru field,
2410 * but it does always reset its private field.
2412 if (!page_private(head
)) {
2413 BUG_ON(count
& COUNT_CONTINUED
);
2414 INIT_LIST_HEAD(&head
->lru
);
2415 set_page_private(head
, SWP_CONTINUED
);
2416 si
->flags
|= SWP_CONTINUED
;
2419 list_for_each_entry(list_page
, &head
->lru
, lru
) {
2423 * If the previous map said no continuation, but we've found
2424 * a continuation page, free our allocation and use this one.
2426 if (!(count
& COUNT_CONTINUED
))
2429 map
= kmap_atomic(list_page
, KM_USER0
) + offset
;
2431 kunmap_atomic(map
, KM_USER0
);
2434 * If this continuation count now has some space in it,
2435 * free our allocation and use this one.
2437 if ((count
& ~COUNT_CONTINUED
) != SWAP_CONT_MAX
)
2441 list_add_tail(&page
->lru
, &head
->lru
);
2442 page
= NULL
; /* now it's attached, don't free it */
2444 spin_unlock(&swap_lock
);
2452 * swap_count_continued - when the original swap_map count is incremented
2453 * from SWAP_MAP_MAX, check if there is already a continuation page to carry
2454 * into, carry if so, or else fail until a new continuation page is allocated;
2455 * when the original swap_map count is decremented from 0 with continuation,
2456 * borrow from the continuation and report whether it still holds more.
2457 * Called while __swap_duplicate() or swap_entry_free() holds swap_lock.
2459 static bool swap_count_continued(struct swap_info_struct
*si
,
2460 pgoff_t offset
, unsigned char count
)
2466 head
= vmalloc_to_page(si
->swap_map
+ offset
);
2467 if (page_private(head
) != SWP_CONTINUED
) {
2468 BUG_ON(count
& COUNT_CONTINUED
);
2469 return false; /* need to add count continuation */
2472 offset
&= ~PAGE_MASK
;
2473 page
= list_entry(head
->lru
.next
, struct page
, lru
);
2474 map
= kmap_atomic(page
, KM_USER0
) + offset
;
2476 if (count
== SWAP_MAP_MAX
) /* initial increment from swap_map */
2477 goto init_map
; /* jump over SWAP_CONT_MAX checks */
2479 if (count
== (SWAP_MAP_MAX
| COUNT_CONTINUED
)) { /* incrementing */
2481 * Think of how you add 1 to 999
2483 while (*map
== (SWAP_CONT_MAX
| COUNT_CONTINUED
)) {
2484 kunmap_atomic(map
, KM_USER0
);
2485 page
= list_entry(page
->lru
.next
, struct page
, lru
);
2486 BUG_ON(page
== head
);
2487 map
= kmap_atomic(page
, KM_USER0
) + offset
;
2489 if (*map
== SWAP_CONT_MAX
) {
2490 kunmap_atomic(map
, KM_USER0
);
2491 page
= list_entry(page
->lru
.next
, struct page
, lru
);
2493 return false; /* add count continuation */
2494 map
= kmap_atomic(page
, KM_USER0
) + offset
;
2495 init_map
: *map
= 0; /* we didn't zero the page */
2498 kunmap_atomic(map
, KM_USER0
);
2499 page
= list_entry(page
->lru
.prev
, struct page
, lru
);
2500 while (page
!= head
) {
2501 map
= kmap_atomic(page
, KM_USER0
) + offset
;
2502 *map
= COUNT_CONTINUED
;
2503 kunmap_atomic(map
, KM_USER0
);
2504 page
= list_entry(page
->lru
.prev
, struct page
, lru
);
2506 return true; /* incremented */
2508 } else { /* decrementing */
2510 * Think of how you subtract 1 from 1000
2512 BUG_ON(count
!= COUNT_CONTINUED
);
2513 while (*map
== COUNT_CONTINUED
) {
2514 kunmap_atomic(map
, KM_USER0
);
2515 page
= list_entry(page
->lru
.next
, struct page
, lru
);
2516 BUG_ON(page
== head
);
2517 map
= kmap_atomic(page
, KM_USER0
) + offset
;
2523 kunmap_atomic(map
, KM_USER0
);
2524 page
= list_entry(page
->lru
.prev
, struct page
, lru
);
2525 while (page
!= head
) {
2526 map
= kmap_atomic(page
, KM_USER0
) + offset
;
2527 *map
= SWAP_CONT_MAX
| count
;
2528 count
= COUNT_CONTINUED
;
2529 kunmap_atomic(map
, KM_USER0
);
2530 page
= list_entry(page
->lru
.prev
, struct page
, lru
);
2532 return count
== COUNT_CONTINUED
;
2537 * free_swap_count_continuations - swapoff free all the continuation pages
2538 * appended to the swap_map, after swap_map is quiesced, before vfree'ing it.
2540 static void free_swap_count_continuations(struct swap_info_struct
*si
)
2544 for (offset
= 0; offset
< si
->max
; offset
+= PAGE_SIZE
) {
2546 head
= vmalloc_to_page(si
->swap_map
+ offset
);
2547 if (page_private(head
)) {
2548 struct list_head
*this, *next
;
2549 list_for_each_safe(this, next
, &head
->lru
) {
2551 page
= list_entry(this, struct page
, lru
);