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Date: Fri, 7 Feb 2014 13:13:06 -0800 (PST)
From: David Rientjes <rientjes@google.com>
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To: Fengguang Wu <fengguang.wu@intel.com>
cc: Tejun Heo <tj@kernel.org>, Filipe David Borba Manana <fdmanana@gmail.com>,
        Chris Mason <clm@fb.com>, linux-btrfs@vger.kernel.org,
        linux-kernel@vger.kernel.org
Subject: Re: [btrfs] BUG: unable to handle kernel NULL pointer dereference
 at 0000000000000038
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On Fri, 7 Feb 2014, Fengguang Wu wrote:

> On Fri, Feb 07, 2014 at 02:13:59AM -0800, David Rientjes wrote:
> > On Fri, 7 Feb 2014, Fengguang Wu wrote:
> > 
> > > [    1.625020] BTRFS: selftest: Running btrfs_split_item tests
> > > [    1.627004] BTRFS: selftest: Running find delalloc tests
> > > [    2.289182] tsc: Refined TSC clocksource calibration: 2299.967 MHz
> > > [  292.084537] kthreadd invoked oom-killer: gfp_mask=0x3000d0, order=1, oom_score_adj=0
> > > [  292.086439] kthreadd cpuset=
> > > [  292.087072] BUG: unable to handle kernel NULL pointer dereference at 0000000000000038
> > > [  292.087372] IP: [<ffffffff812119de>] pr_cont_kernfs_name+0x1b/0x6c
> > 
> > This looks like a problem with the cpuset cgroup name, are you sure this 
> > isn't related to the removal of cgroup->name?
> 
> It looks not related to patch "cgroup: remove cgroup->name", because
> that patch lies in the cgroup tree and not contained in output of "git log BAD_COMMIT".
> 

It's dying on pr_cont_kernfs_name which is some tree that has "kernfs: 
implement kernfs_get_parent(), kernfs_name/path() and friends", which is 
not in linux-next, and is obviously printing the cpuset cgroup name.

It doesn't look like it has anything at all to do with btrfs or why they 
would care about this failure.