Messages in this thread | | | Date | Sat, 8 Feb 2014 15:10:37 -0500 | From | Tejun Heo <> | Subject | Re: [btrfs] BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 |
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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
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