Re: OOM-killer and strange RSS value in 3.9-rc7

From: Michal Hocko <mhocko@suse.cz>
To: Han Pingtian <hanpt@linux.vnet.ibm.com>
Cc: linux-kernel@vger.kernel.org, rientjes@google.com
Subject: Re: OOM-killer and strange RSS value in 3.9-rc7
Date: Mon, 22 Apr 2013 13:40:52 +0200	[thread overview]
Message-ID: <20130422114052.GB18286@dhcp22.suse.cz> (raw)
In-Reply-To: <20130422031849.GG2672@localhost.localdomain>

On Mon 22-04-13 11:18:49, Han Pingtian wrote:
> On Fri, Apr 19, 2013 at 09:43:10AM -0700, Michal Hocko wrote:
> > [Do not drop people from the CC please]
> > 
> > On Fri 19-04-13 10:33:45, Han Pingtian wrote:
> > > On Thu, Apr 18, 2013 at 10:55:14AM -0700, Michal Hocko wrote:
> > [...]
> > > > What is the kernel that you are using and what config?
> > > > 
> > > We are testing a alpha version of a enterprise linux which using a 3.7
> > > series kernel. On this 3.7 kernel we encountered the oom killer problem. So
> > > we decide to see if the problem can be reproduced on 3.9-rc7. We
> > > configured 3.9-rc7 by copying the enterprise linux's config file to
> > > .config and then run 'make localmodconfig' and pressed enter to all the
> > > questions. Then the oom problem is reproduced on the 3.9-rc7.
> > > 
> > > But we also used the same method to config 3.9-rc7 on another company's
> > > enterprise linux yesterday and found that the problem cannot be
> > > reproduced there. So maybe the leak is caused by some userspace
> > > applications?
> > 
> > No application should cause in-kernel mem leak. What is the difference
> > in the two configs?
> 
> This is the diff output of those two .config:
> 
> 
> --- /tmp/config.bad	2013-04-21 22:03:13.000000000 -0500
> +++ /tmp/config.good	2013-04-21 22:03:27.000000000 -0500
> @@ -9,21 +9,21 @@
>  #
>  CONFIG_PPC_BOOK3S_64=y
>  # CONFIG_PPC_BOOK3E_64 is not set
> -CONFIG_GENERIC_CPU=y
> +# CONFIG_GENERIC_CPU is not set
>  # CONFIG_CELL_CPU is not set
>  # CONFIG_POWER4_CPU is not set
>  # CONFIG_POWER5_CPU is not set
>  # CONFIG_POWER6_CPU is not set
> -# CONFIG_POWER7_CPU is not set
> +CONFIG_POWER7_CPU=y

Wow, so the two configs are for different architectures? Not very much
helpful. Could you stick with a single machine and do just small updates
to the config to the point where the problem is no longer present,
please?

[...]
> -CONFIG_MEMCG=y
> -CONFIG_MEMCG_SWAP=y
> -CONFIG_MEMCG_SWAP_ENABLED=y
> -CONFIG_MEMCG_KMEM=y
> +# CONFIG_MEMCG is not set

Is it possible that you have used MEMCG resp. KMEM extension in the bad
config configuration?

[...]
> -CONFIG_SLUB_DEBUG=y
> -# CONFIG_COMPAT_BRK is not set
> -# CONFIG_SLAB is not set
> -CONFIG_SLUB=y
> +CONFIG_COMPAT_BRK=y
> +CONFIG_SLAB=y

I would start with the bad config and SLUB changed to SLAB in the first
step, though.

[...]
-- 
Michal Hocko
SUSE Labs