[systemd-devel] BTRFS bug with parallel mounts?

[Gustavo Sverzut Barbieri]

On Thursday, November 11, 2010, Mike Kazantsev <mk.fraggod at gmail.com> wrote:
> On Wed, 10 Nov 2010 15:52:51 -0200
> Gustavo Sverzut Barbieri <barbieri at profusion.mobi> wrote:
>
>> On Wed, Nov 10, 2010 at 2:11 PM, Greg KH <greg at kroah.com> wrote:
>> > On Wed, Nov 10, 2010 at 01:02:51PM -0200, Gustavo Sverzut Barbieri wrote:
>> >> On Wed, Nov 10, 2010 at 9:33 AM, Gustavo Sverzut Barbieri
>> >>
>> >> Part of the log (sorry, I had no way but to type it all):
>> >>
>> >> BUG: unable to handle kernel NULL pointer dereference at 0000000000000128
>> >> IP: [<ffffffff811329fb>] btrfs_test_super+0xb/0x30
>> >> PGD: 26b5b1067 PUD 26a465067 PMD 0
>> >> last sysfs file: /sys/devices/virtual/bdi/btrfs-2/uevent
>> >> CPU 0
>> >> Modules linked in: nvidia(P) lib80211_crypt_tkip wl(P)
>> >> Pid: 434, comm: mount Tainted: P     2.6.36 #3 Mac-F22586C8/MacBookPro6,2
>> >> RIP: ... btrfs_test_super+0xb/0x30
>> >
>> > Sounds like a btrfs issue, have you contacted those developers?
>>
>> No, I just mailed systemd as people (kay?) seems to be using it, at
>> least I saw people here advertising its usage, even the readahead have
>> specific code, so maybe people had (or not) issues with it.
>>
>> Let's face that mounting multiple points simultaneously is not what
>> one would expect.
>>
>>
>> > Also, you really are going to have to be able to reproduce this without
>> > the closed source kernel modules linked in (broadcom and nvidia) for
>> > anyone to even be able to help you out.
>>
>> yeah, I'm pretty sure about that ;-)
>>
>
> I can reliably reproduce the issue on my hardware and similar vm setup
> with several btrfs mounts, activated during boot.
> Kernel spits some backtrace into terminal, then, after a few seconds it
> enters some kind of crazy endless error-loop, flooding terminal with
> more backtraces.
> Vanilla 2.6.36 kernel, no proprietary code.
>
> Since none of these mounts are critical to boot (I didn't trust btrfs
> much at the time), I've worked around the issue by
> comment=systemd.automount, so they got mounted after boot with systemd.
>
> I thought about reporting the issue when I've encountered it, but been
> a bit busy adapting the system for systemd, so it kina slipped off my
> mind.
> Guess I'll get all these traces, clean my vm from possible private
> stuff (I rsync it from a real machine) and report the setup to btrfs
> maintainers in a few days.
> Thanks for reminder! ;)

I'd appreciate it as I'm going into a business trip without much spare
time do do dev/testing. If possible, add me as mail/bugzilla CC

-- 
Gustavo Sverzut Barbieri
http://profusion.mobi embedded systems
--------------------------------------
MSN: barbieri at gmail.com
Skype: gsbarbieri
Mobile: +55 (19) 9225-2202