Re: KVM induced panic on 2.6.38[2367] & 2.6.39

Avi Kivity
2011-08-22T06:36:04Z

On 08/20/2011 04:16 PM, Brad Campbell wrote:
> Author: Alexander Duyck <alexander.h.duyck@intel.com>
> Date: Thu Jul 1 13:28:27 2010 +0000
>
> x86: Drop CONFIG_MCORE2 check around setting of NET_IP_ALIGN
>
> This patch removes the CONFIG_MCORE2 check from around
> NET_IP_ALIGN. It is
> based on a suggestion from Andi Kleen. The assumption is that
> there are
> not any x86 cores where unaligned access is really slow, and this
> change
> would allow for a performance improvement to still exist on
> configurations
> that are not necessarily optimized for Core 2.
>
> Cc: Andi Kleen <ak@linux.intel.com>
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Cc: x86@kernel.org
> Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
> Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
> Acked-by: H. Peter Anvin <hpa@zytor.com>
> Signed-off-by: David S. Miller <davem@davemloft.net>
>
> :040000 040000 5a15867789080a2f67a74b17c4422f85b7a9fb4a
> b98769348bd765731ca3ff03b33764257e23226c M arch
>
> I can confirm this bug exists in the 3.0 kernel, however I'm unable to
> reproduce it on todays git.
>
> So anyone using netfilter, kvm and bridge on kernels between
> 2.6.36-rc1 and 3.0 may hit this bug, but it looks like it is fixed in
> the current 3.1-rc kernels.
>

Thanks for this effort. I don't think this patch is buggy in itself, it
merely exposed another bug which was fixed later on.

--
I have a truly marvellous patch that fixes the bug which this
signature is too narrow to contain.