Messages in this thread | | | From | Greg Thelen <> | Subject | Re: [patch 2/4] memcg: catch negative per-cpu sums in dirty info | Date | Mon, 08 Nov 2010 14:28:46 -0800 |
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Minchan Kim <minchan.kim@gmail.com> writes:
> 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> Reviewed-by: Greg Thelen <gthelen@google.com>
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