linux-kernel - Re: System freeze on reboot

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Date:	Thu, 13 Aug 2009 00:16:00 +0200
From:	Zdenek Kabelac <zdenek.kabelac@...il.com>
To:	Robin Holt <holt@....com>
Cc:	Christoph Lameter <cl@...ux-foundation.org>,
	Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
	Pekka Enberg <penberg@...helsinki.fi>,
	Jesper Dangaard Brouer <hawk@...x.dk>,
	Eric Dumazet <eric.dumazet@...il.com>
Subject: Re: System freeze on reboot - general protection fault

2009/8/11 Zdenek Kabelac <zdenek.kabelac@...il.com>:
> 2009/8/11 Robin Holt <holt@....com>:
>> On Tue, Aug 11, 2009 at 05:32:16PM +0200, Zdenek Kabelac wrote:
>>> 2009/8/11 Christoph Lameter <cl@...ux-foundation.org>:
>>> > On Tue, 11 Aug 2009, Zdenek Kabelac wrote:
>>> >
>>> >> Well - I've tried to switch from  'slub' allocator to  old 'slab'
>>> >> allocator and the problem is gone - shutdown goes without any problem.
>>> >>
>>> >> So it's probably related to 'slub' allocator only?
>>> >
>>> > The slab allocator does not have all the diagnostics of slub. The issue
>>> > may simply not be detected in slab. If you switch off diagnostics in slub
>>> > then everything will seem to work fine as well. But we need to figure out
>>> > what is going wrong here.
>>>
>>> Hmm - but there are few things -
>>>
>>> My machine runs  Fedora Rawhide. If I run the same kernel within KVM
>>> running Debian unstable I could easily reboot this guest machine
>>> without any problems.
>>>
>>> Also if I boot Rawhide only to single mode - I could also reboot
>>> machine without this oops.
>>> The problem seems to be - when I do full machine startup to the
>>> multiuser runlevel 3
>>
>> Try booting all the way and recording you output from lsmod.  Reboot
>> single user mode and modprobe each of the modules in that original lists.
>> Test shutdown from single user mode.  This might identify if it is one
>> of your loaded modules.  If so, effectively bisect the modprobes until
>> you find the offending module(s).
>>
>
>
> Ok - it appeared to be more complex - when I've been trying to get
> this oops on my laptop while not being connected via wired net - but
> to not bother here with details - the result is
>
> That if I remove nf_conntrack_ipv4.ko  - so it can not be loaded - the
> problem is gone.
> So it looks like the memory problem is related to netfiltering - there
> are multiple modules loaded as dependecy becuase of this - so it's
> hard to say exactly which module of them makes the trouble.
>
> I've checked for some recent commits in this area - and they seem to
> be actually important
> (i.e 941297f443f871b8c3372feccf27a8733f6ce9e9  16.Jul)
>
> I could probably try to revert some of them - but if someone has some
> ideas what could make these problems ?
>
> I've added authors of some recent conntrack commits to Cc: - maybe
> they might know?

I've tested v2.6.30 - and it's crashing in the same way - so any other
starting point where slub has the same detection mechanism and
conntrack module should be working reliable ?

Zdenek
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