Re: [Bisected][-next-20130204+] [x86/kvm] udevd:[97]: segfault at ffffffffff5fd020 ip 00007fff069e277f sp 00007fff068c9ef8 error d

[Peter Hurley <peter@hurleysoftware.com>]

On Mon, 2013-02-18 at 19:59 -0300, Marcelo Tosatti wrote:
> On Wed, Feb 13, 2013 at 06:57:09AM -0500, Peter Hurley wrote:
> > On Wed, 2013-02-13 at 12:51 +0200, Gleb Natapov wrote:
> > > On Tue, Feb 12, 2013 at 04:39:03PM -0800, H. Peter Anvin wrote:
> > > > On 02/12/2013 04:26 PM, Peter Hurley wrote:
> > > > > With -next-20130204+ in ubuntu 12.10 VM (so the 80x25 VGA
> > > > > device/console):
> > > > > 
> > > > > [    0.666410] udevd[97]: starting version 175
> > > > > [    0.674043] udevd[97]: udevd:[97]: segfault at ffffffffff5fd020 ip 00007fff069e277f sp 00007fff068c9ef8 error d
> > > > > 
> > > > > and boots to an initramfs prompt.
> > > > > 
> > > > > git bisect (log attached) blames:
> > > > > 
> > > > > commit 7b5c4a65cc27f017c170b025f8d6d75dabb11c6f
> > > > > Merge: 3596f5b 949db15
> > > > > Author: H. Peter Anvin <hpa@linux.intel.com>
> > > > > Date:   Fri Jan 25 16:31:21 2013 -0800
> > > > > 
> > > > >     Merge tag 'v3.8-rc5' into x86/mm
> > > > >     
> > > > >     The __pa() fixup series that follows touches KVM code that is not
> > > > >     present in the existing branch based on v3.7-rc5, so merge in the
> > > > >     current upstream from Linus.
> > > > >     
> > > > >     Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
> > > > > 
> > > > > 
> > > > > This only happens with the VGA device/console but that is the default
> > > > > configuration for Ubuntu/KVM because it blacklists pretty much every fb
> > > > > driver.
> > > > > 
> > > > 
> > > > I am guessing this is another bad use of __pa()... need to look into that.
> 
> Can't find this commit on kvm.git or linux-2.6.git. Is it reproducible
> there?

This is in the linux-next repo (any git tag after 'next-20130204' will
reproduce this). It's a pretty large merge commit.

This doesn't happen on 3.8-rc7.

I'll try to repro this on kvm.git sometime this week. Otherwise, we can
wait for it to show up in 3.9.

Regards,
Peter Hurley