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author | Minchan Kim <minchan@kernel.org> | 2012-07-31 23:43:53 (GMT) |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2012-08-01 01:42:45 (GMT) |
commit | 2cfed0752808625d30aca7fc9f383af386fd8a13 (patch) | |
tree | 5e92da86e42e55b253cc04e10545e05b6b472542 /include | |
parent | ee6f509c3274014d1f52e7a7a10aee9f85393c5e (diff) | |
download | linux-fsl-qoriq-2cfed0752808625d30aca7fc9f383af386fd8a13.tar.xz |
mm: fix free page check in zone_watermark_ok()
__zone_watermark_ok currently compares free_pages which is a signed type
with z->lowmem_reserve[classzone_idx] which is unsigned which might lead
to sign overflow if free_pages doesn't satisfy the given order (or it came
as negative already) and then we rely on the following order loop to fix
it (which doesn't work for order-0). Let's fix the type conversion and do
not rely on the given value of free_pages or follow up fixups.
This patch fixes it because "memory-hotplug: fix kswapd looping forever
problem" depends on this.
As benefit of this patch, it doesn't rely on the loop to exit
__zone_watermark_ok in case of high order check and make the first test
effective.(ie, if (free_pages <= min + lowmem_reserve))
Aaditya reported this problem when he test my hotplug patch.
Reported-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com>
Tested-by: Aaditya Kumar <aaditya.kumar@ap.sony.com>
Signed-off-by: Aaditya Kumar <aaditya.kumar@ap.sony.com>
Signed-off-by: Minchan Kim <minchan@kernel.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Reviewed-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'include')
0 files changed, 0 insertions, 0 deletions