Re: [stable] [tip:x86/urgent] x86: Add memory modify constraints to xchg() and cmpxchg()

Tomáš Janoušek
2010-09-09T20:27:06Z

Hello,

2.6.32.21 does not boot on my HP Compaq nx7300. I bisected it to this patch:

On Mon, Aug 02, 2010 at 04:59:50PM -0700, Greg KH wrote:
> On Mon, Aug 02, 2010 at 04:51:27PM -0700, Jeremy Fitzhardinge wrote:
> > On 07/27/2010 10:33 PM, tip-bot for H. Peter Anvin wrote:
> > >Commit-ID: 113fc5a6e8c2288619ff7e8187a6f556b7e0d372
> > >Gitweb: http://git.kernel.org/tip/113fc5a6e8c2288619ff7e8187a6f556b7e0d372
> > >Author: H. Peter Anvin<hpa@zytor.com>
> > >AuthorDate: Tue, 27 Jul 2010 17:01:49 -0700
> > >Committer: H. Peter Anvin<hpa@zytor.com>
> > >CommitDate: Tue, 27 Jul 2010 17:14:02 -0700
> > >
> > >x86: Add memory modify constraints to xchg() and cmpxchg()
> >
> > Here's the 2.6.32 version for stable.
>
> Thanks, I'll queue it up when it hits Linus's tree.

Here's a video of the crash: http://store.lisk.in/tmp/09092010019.mp4
With boot_delay=30, it sometimes just reboots and sometimes prints the trace.
Without it, it always prints the trace. The crash occurs during the
initialization of intel-agp (which explains why I can't reproduce it in qemu).
More details in the video.

The system boots and works just fine with 2.6.32.21 with the patch reverted.
v2.6.36-rc3-185-gd56557a works fine as well, perhaps there were other fixes
that didn't get to stable (e.g. 4532b30).

I'm compiling the kernel with the latest gcc in Debian (-dumpversion says
4.4.5, dpkg reports 4:4.4.4-2). Shall I post dmesg/lspci as well?

Since I have an easy workaround and other things to do, I won't spend time
trying to backport those other fixes myself, but if you're going to fix this,
I will help with testing.

Regards,
--
Tomáš Janoušek, a.k.a. Liskni_si, http://work.lisk.in/