Message-ID: <4DF24D04.1080802@redhat.com>
Date: Fri, 10 Jun 2011 18:57:40 +0200
From: Igor Mammedov <imammedo@redhat.com>
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To: Andrew Morton <akpm@linux-foundation.org>
CC: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
        Hiroyuki Kamezawa <kamezawa.hiroyuki@gmail.com>,
        Michal Hocko <mhocko@suse.cz>, linux-kernel@vger.kernel.org,
        balbir@linux.vnet.ibm.com, linux-mm@kvack.org,
        Paul Menage <menage@google.com>, Li Zefan <lizf@cn.fujitsu.com>,
        containers@lists.linux-foundation.org,
        Tim Deegan <Tim.Deegan@citrix.com>
Subject: Re: [PATCH] memcg: do not expose uninitialized mem_cgroup_per_node
 to world
References: <1306925044-2828-1-git-send-email-imammedo@redhat.com>	<20110601123913.GC4266@tiehlicka.suse.cz>	<4DE6399C.8070802@redhat.com>	<20110601134149.GD4266@tiehlicka.suse.cz>	<4DE64F0C.3050203@redhat.com>	<20110601152039.GG4266@tiehlicka.suse.cz>	<4DE66BEB.7040502@redhat.com>	<BANLkTimbqHPeUdue=_Z31KVdPwcXtbLpeg@mail.gmail.com>	<4DE8D50F.1090406@redhat.com>	<BANLkTinMamg_qesEffGxKu3QkT=zyQ2MRQ@mail.gmail.com>	<4DEE26E7.2060201@redhat.com>	<20110608123527.479e6991.kamezawa.hiroyu@jp.fujitsu.com> <20110608140951.115ab1dd.akpm@linux-foundation.org>
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On 06/08/2011 11:09 PM, Andrew Morton wrote:
> The original patch:
>
> --- a/mm/memcontrol.c
> +++ b/mm/memcontrol.c
> @@ -4707,7 +4707,6 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
>   	if (!pn)
>   		return 1;
>
> -	mem->info.nodeinfo[node] = pn;
>   	for (zone = 0; zone<  MAX_NR_ZONES; zone++) {
>   		mz =&pn->zoneinfo[zone];
>   		for_each_lru(l)
> @@ -4716,6 +4715,7 @@ static int alloc_mem_cgroup_per_zone_info(struct mem_cgroup *mem, int node)
>   		mz->on_tree = false;
>   		mz->mem = mem;
>   	}
> +	mem->info.nodeinfo[node] = pn;
>   	return 0;
>   }
>
> looks like a really good idea.  But it needs a new changelog and I'd be
> a bit reluctant to merge it as it appears that the aptch removes our
> only known way of reproducing a bug.
>
> So for now I think I'll queue the patch up unchangelogged so the issue
> doesn't get forgotten about.
>
Problem was in rhel's xen hv.
It was missing fix for imul emulation.
Details here 
http://lists.xensource.com/archives/html/xen-devel/2011-06/msg00801.html
Thanks to Tim Deegan and everyone who was involved in the discussion.

-- 
Thanks,
  Igor

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