Re: [PATCH] memcg: Fix race condition in memcg_check_events() withthis_cpu usage

From: Greg Thelen
Date: Fri Sep 23 2011 - 22:39:36 EST


cc: updated Balbir Singh email address

On Fri, Sep 23, 2011 at 7:34 PM, Greg Thelen <gthelen@xxxxxxxxxx> wrote:
> On Fri, Sep 23, 2011 at 5:54 PM, Steven Rostedt <rostedt@xxxxxxxxxxx> wrote:
>> From: Steven Rostedt <srostedt@xxxxxxxxxx>
>>
>> The code in memcg_check_events() calls this_cpu_read() on
>> different variables without disabling preemption, and can cause
>> the calculations to be done from two different CPU variables.
>>
>> Disable preemption throughout the check to keep apples and oranges
>> from becoming a mixed drink.
>>
>> [ Added this_cpu to __this_cpu conversion by Johannes ]
>>
>> Cc: Greg Thelen <gthelen@xxxxxxxxxx>
>> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
>> Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>

Correction:
Cc: Balbir Singh <bsingharora@xxxxxxxxx>

>> Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
>> Cc: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
>> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
>> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
>> Cc: Christoph Lameter <cl@xxxxxxxxx>
>> Signed-off-by: Johannes Weiner <hannes@xxxxxxxxxxx>
>> Signed-off-by: Steven Rostedt <rostedt@xxxxxxxxxxx>
>> Link: http://lkml.kernel.org/r/20110919212641.015320989@xxxxxxxxxxx
>
> Looks good to me.  Thanks.
>
> Reviewed-by: Greg Thelen <gthelen@xxxxxxxxxx>
>
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