diff options
| author | KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> | 2010-08-09 17:20:09 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2010-08-09 20:45:04 -0700 |
| commit | 966cca029f739716fbcc8068b8c6dfe381f86fc3 (patch) | |
| tree | 838686762076c262c425e3dc09d0cda4e9e5e83d /mm/swapfile.c | |
| parent | 979f867191f80e74713394cf8c0a3c1b3662b648 (diff) | |
mm: fix corruption of hibernation caused by reusing swap during image saving
Since 2.6.31, swap_map[]'s refcounting was changed to show that a used
swap entry is just for swap-cache, can be reused. Then, while scanning
free entry in swap_map[], a swap entry may be able to be reclaimed and
reused. It was caused by commit c9e444103b5e7a5 ("mm: reuse unused swap
entry if necessary").
But this caused deta corruption at resume. The scenario is
- Assume a clean-swap cache, but mapped.
- at hibernation_snapshot[], clean-swap-cache is saved as
clean-swap-cache and swap_map[] is marked as SWAP_HAS_CACHE.
- then, save_image() is called. And reuse SWAP_HAS_CACHE entry to save
image, and break the contents.
After resume:
- the memory reclaim runs and finds clean-not-referenced-swap-cache and
discards it because it's marked as clean. But here, the contents on
disk and swap-cache is inconsistent.
Hance memory is corrupted.
This patch avoids the bug by not reclaiming swap-entry during hibernation.
This is a quick fix for backporting.
Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Rafael J. Wysocki <rjw@sisk.pl>
Reported-by: Ondreg Zary <linux@rainbow-software.org>
Tested-by: Ondreg Zary <linux@rainbow-software.org>
Tested-by: Andrea Gelmini <andrea.gelmini@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/swapfile.c')
| -rw-r--r-- | mm/swapfile.c | 6 |
1 files changed, 4 insertions, 2 deletions
diff --git a/mm/swapfile.c b/mm/swapfile.c index 03aa2d55f1a..f08d165871b 100644 --- a/mm/swapfile.c +++ b/mm/swapfile.c @@ -318,8 +318,10 @@ checks: if (offset > si->highest_bit) scan_base = offset = si->lowest_bit; - /* reuse swap entry of cache-only swap if not busy. */ - if (vm_swap_full() && si->swap_map[offset] == SWAP_HAS_CACHE) { + /* reuse swap entry of cache-only swap if not hibernation. */ + if (vm_swap_full() + && usage == SWAP_HAS_CACHE + && si->swap_map[offset] == SWAP_HAS_CACHE) { int swap_was_freed; spin_unlock(&swap_lock); swap_was_freed = __try_to_reclaim_swap(si, offset); |