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    SubjectRe: [patch 2/4] memcg: catch negative per-cpu sums in dirty info
    On Sun,  7 Nov 2010 23:14:37 +0100
    Johannes Weiner <> 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 <>

    Acked-by: KAMEZAWA Hiroyuki <>

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