From: Tejun Heo <tj@kernel.org>
To: David Rientjes <rientjes@google.com>
Cc: Fengguang Wu <fengguang.wu@intel.com>,
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
Date: Sat, 8 Feb 2014 15:10:37 -0500 [thread overview]
Message-ID: <20140208201037.GC10975@htj.dyndns.org> (raw)
In-Reply-To: <alpine.DEB.2.02.1402071307590.4212@chino.kir.corp.google.com>
Hello, David, Fengguang, Chris.
On Fri, Feb 07, 2014 at 01:13:06PM -0800, David Rientjes wrote:
> 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.
Yeah, this is from a patch in cgroup/review-post-kernfs-conversion
branch which updates cgroup to use pr_cont_kernfs_name(). I forget
that cgrp->kn is NULL for the dummy_root's top cgroup and thus it ends
up calling the kernfs functions with NULL kn and thus the oops. I
posted an updated patch and the git branch has been updated.
http://lkml.kernel.org/g/20140208200640.GB10975@htj.dyndns.org
So, nothing to do with btrfs and it looks like somehow the test
appratus is mixing up branches?
Thanks!
--
tejun
next prev parent reply other threads:[~2014-02-08 20:10 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <20140207023801.GC11051@localhost>
2014-02-07 10:13 ` [btrfs] BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 David Rientjes
2014-02-07 12:10 ` Fengguang Wu
2014-02-07 15:10 ` Chris Mason
2014-02-07 15:22 ` Filipe David Manana
2014-02-08 13:07 ` Fengguang Wu
2014-02-10 9:12 ` Fengguang Wu
2014-02-07 21:13 ` David Rientjes
2014-02-08 20:10 ` Tejun Heo [this message]
2014-02-10 9:25 ` Fengguang Wu
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