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| author | Sonny Rao <sonnyrao@chromium.org> | 2012-12-20 15:05:07 -0800 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-01-11 09:06:48 -0800 |
| commit | 711cf004f2148f1d1967bc5eca025019e5001212 (patch) | |
| tree | 83ba439251b29610cc5ea1f6626d0190521769d9 /mm/backing-dev.c | |
| parent | 6cb6a94380506d9e5491b8e145811bd676ce6f3d (diff) | |
mm: fix calculation of dirtyable memory
commit c8b74c2f6604923de91f8aa6539f8bb934736754 upstream.
The system uses global_dirtyable_memory() to calculate number of
dirtyable pages/pages that can be allocated to the page cache. A bug
causes an underflow thus making the page count look like a big unsigned
number. This in turn confuses the dirty writeback throttling to
aggressively write back pages as they become dirty (usually 1 page at a
time). This generally only affects systems with highmem because the
underflowed count gets subtracted from the global count of dirtyable
memory.
The problem was introduced with v3.2-4896-gab8fabd
Fix is to ensure we don't get an underflowed total of either highmem or
global dirtyable memory.
Signed-off-by: Sonny Rao <sonnyrao@chromium.org>
Signed-off-by: Puneet Kumar <puneetster@chromium.org>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Tested-by: Damien Wyart <damien.wyart@free.fr>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'mm/backing-dev.c')
0 files changed, 0 insertions, 0 deletions