From: Martin <marogge@onlinehome.de>
To: "vger.kernel.org, " <linux-kernel@vger.kernel.org>, wzab@ise.pw.edu.pl
Subject: Re: Kernel panic on HT machine - maybe i915 related?
Date: Wed, 15 Jun 2011 22:24:34 +0200
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wzab wrote:

> Hi,
> I tried to find the source of the problem I experience, supposing, that
> it may affect also other users of machine with Hyper-Threaded CPU.
> [...]

Hi wzab et al, 

only today I have started to use a spare machine at work, with a hyperthreaded 
CPU (P4 3.2GHz). I also experience random kernel panics with 2.6.39.1 and 
SMP/HT enabled. The machine usually runs for a couple of hours before the 
panic occurs.

> Crash seems to happen in random places:
> [...]

Same here, although my panics look different from yours. In both cases I had a 
lot of hardware interrupts on the stack trace but no kmemcheck. I only 
remembered to take a photo with my mobile phone the second time. The stack 
trace contains handle_*irq*, tg3, ata_bmdma, __ata_sff, i915, drm_vblank_put, 
intel_thermal, try_preempt, resched*, drm_vblank_put, do_invalid_op, oops_end, 
do_bounds, panic. The EIP is drm_vblank_put+0x13/0x50.

Could this be an i915 issue with 2.6.39.1? At home I have two other machines 
on i915 but with different chipsets that run fine with the same kernel.

> As crash occurs only with HT on and doesn't happen on another machine
> with 2 cores, it seems that maybe the problem is associated with
> incorrect allocation of resources or locking for HT enabled CPU...

I do not observe the issue with the regular non-SMP 2.6.38.7 distro kernel, so 
it might be HT related. Truth be told I need to investigate further since my 
2.6.39.1 kernel is patched. In the meantime, if someone recognizes the issue 
please come forward.

Thanks and regards,

Martin
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