Re: Linux 2.6.35.3

H. Peter Anvin
2010-08-21T03:45:05Z

On 08/20/2010 08:40 PM, Mark Stanovich wrote:
> After updating to the 2.6.35.3 stable release, my machine was rebooting
> automatically during the first few seconds of boot.
>
> I bisected to the first bad commit of
>
> commit 568132624386f53e87575195d868db
> 9afb2e9316
> Author: H. Peter Anvin <hpa@zytor.com <mailto:hpa@zytor.com>>
> Date: Tue Jul 27 17:01:49 2010 -0700
>
> x86: Add memory modify constraints to xchg() and cmpxchg()
>
> commit 113fc5a6e8c2288619ff7e8187a6f556b7e0d372 upstream.
>
> xchg() and cmpxchg() modify their memory operands, not merely read
> them. For some versions of gcc the "memory" clobber has apparently
> dealt with the situation, but not for all.
>
> I noticed that the latest version pulled from Linus's git tree did not
> have the problem. After looking at the changes to
> arch/x86/include/asm/cmpxchg_32.h, I cherry-picked two patches from
> Linus's tree that seemed to make a difference, namely:
>
> 69309a05907546fb686b251d4ab041c26afe1e1d
> 4532b305e8f0c238dd73048068ff8a6dd1380291
>
> Applying these patches solved the rebooting problem on 2.6.35.3
>
> I believe the same problem also happens for the latest stable version of
> 2.6.34, but did not verify the fix worked for the 2.6.34 stable releases.
>
> I don't know if this is helpful, but I thought I would let you know in
> case someone else is having the same problem.
>
> If you need any further information, just let me know.
>

Yes, as a matter of fact, we have been trying to root-cause this
problem; please see:

https://bugzilla.kernel.org/show_bug.cgi?id=16612

If you could try the one-liner in there and see if it solves your
problem, it would be great.

-hpa

P.S. What version of gcc do you use?

--
H. Peter Anvin, Intel Open Source Technology Center
I work for Intel. I don't speak on their behalf.