Messages in this thread | | | Date | Mon, 8 Nov 2010 08:26:29 +0900 | Subject | Re: [patch 2/4] memcg: catch negative per-cpu sums in dirty info | From | Minchan Kim <> |
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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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