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    SubjectRe: [patch 2/4] memcg: catch negative per-cpu sums in dirty info
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    On Mon, Nov 8, 2010 at 7:14 AM, Johannes Weiner <hannes@cmpxchg.org> wrote:
    > Folding the per-cpu counters can yield a negative value in case of
    > accounting races between CPUs.
    >
    > When collecting the dirty info, the code would read those sums into an
    > unsigned variable and then check for it being negative, which can not
    > work.
    >
    > Instead, fold the counters into a signed local variable, make the
    > check, and only then assign it.
    >
    > This way, the function signals correctly when there are insane values
    > instead of leaking them out to the caller.
    >
    > Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
    Reviewed-by: Minchan Kim <minchan.kim@gmail.com>


    --
    Kind regards,
    Minchan Kim


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