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

Greg Thelen
2011-09-24T02:39:33Z

cc: updated Balbir Singh email address

On Fri, Sep 23, 2011 at 7:34 PM, Greg Thelen <gthelen@google.com> wrote:
> On Fri, Sep 23, 2011 at 5:54 PM, Steven Rostedt <rostedt@goodmis.org> wrote:
>> From: Steven Rostedt <srostedt@redhat.com>
>>
>> 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@google.com>
>> Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>> Cc: Balbir Singh <balbir@linux.vnet.ibm.com>

Correction:
Cc: Balbir Singh <bsingharora@gmail.com>

>> Cc: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
>> Cc: Andrew Morton <akpm@linux-foundation.org>
>> Cc: Thomas Gleixner <tglx@linutronix.de>
>> Cc: Peter Zijlstra <peterz@infradead.org>
>> Cc: Christoph Lameter <cl@linux.com>
>> Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
>> Signed-off-by: Steven Rostedt <rostedt@goodmis.org>
>> Link: http://lkml.kernel.org/r/20110919212641.015320989@goodmis.org
>
> Looks good to me.  Thanks.
>
> Reviewed-by: Greg Thelen <gthelen@google.com>
>