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Date: Tue, 14 Sep 2010 00:28:30 +0900
Message-ID: <AANLkTimsUQuEeS2QvSwY_WhnQY7n=D73fNmOoqgrTqbZ@mail.gmail.com>
Subject: Re: [BUGFIX][PATCH] memcg: fix race in file_mapped accouting flag management
From: Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>
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Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>, "linux-mm@kvack.org" <linux-mm@kvack.org>, "nishimura@mxp.nes.nec.co.jp" <nishimura@mxp.nes.nec.co.jp>, gthelen@google.com, "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>, "akpm@linux-foundation.org" <akpm@linux-foundation.org>, stable@kernel.org
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2010/9/13 Balbir Singh <balbir@linux.vnet.ibm.com>:
> * KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2010-09-13 16:08:22=
]:
>
>>
>> I think this small race is not very critical but it's bug.
>> We have this race since 2.6.34.
>> =3D
>> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>>
>> Now. memory cgroup accounts file-mapped by counter and flag.
>> counter is working in the same way with zone_stat but FileMapped flag on=
ly
>> exists in memcg (for helping move_account).
>>
>> This flag can be updated wrongly in a case. Assume CPU0 and CPU1
>> and a thread mapping a page on CPU0, another thread unmapping it on CPU1=