Messages in this thread | | | Date | Tue, 16 Nov 2010 12:39:12 +0900 | From | KAMEZAWA Hiroyuki <> | Subject | Re: [patch 2/4] memcg: catch negative per-cpu sums in dirty info |
| |
On Sun, 7 Nov 2010 23:14:37 +0100 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>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
| |