Message-ID: <4966A117.9030201@cn.fujitsu.com>
Date: Fri, 09 Jan 2009 08:57:59 +0800
From: Li Zefan <lizf@cn.fujitsu.com>
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To: Daisuke Nishimura <nishimura@mxp.nes.nec.co.jp>
CC: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
       kamezawa.hiroyu@jp.fujitsu.com, balbir@linux.vnet.ibm.com,
       menage@google.com
Subject: Re: [RFC][PATCH 1/4] memcg: fix for mem_cgroup_get_reclaim_stat_from_page
References: <20090108190818.b663ce20.nishimura@mxp.nes.nec.co.jp> <20090108191430.af89e037.nishimura@mxp.nes.nec.co.jp>
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> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> index e2996b8..62e69d8 100644
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -559,6 +559,10 @@ mem_cgroup_get_reclaim_stat_from_page(struct page *page)
>  		return NULL;
>  
>  	pc = lookup_page_cgroup(page);
> +	smp_rmb();

It is better to add a comment to explain this smp_rmb. I think it's recommended
that every memory barrier has a comment.

> +	if (!PageCgroupUsed(pc))
> +		return NULL;
> +
>  	mz = page_cgroup_zoneinfo(pc);
>  	if (!mz)
>  		return NULL;
> 
> 
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