Re: BUG() with SCSI-interfaced disk images

Ryan Harper
2009-01-08T14:01:06Z

* John Morrissey <jwm@horde.net> [2009-01-07 20:16]:
> On Wed, Jan 07, 2009 at 04:34:50PM -0600, Ryan Harper wrote:
> > * John Morrissey <jwm@horde.net> [2009-01-07 15:59]:
> > > On Fri, Dec 26, 2008 at 04:00:28PM -0500, John Morrissey wrote:
> > > > I'm encountering a kernel BUG() in guests using SCSI-interfaced disk
> > > > images. I've tried with the Debian packaging of KVM 79 and 82; both
> > > > exhibit the same behavior (disclaimer: Debian has about a dozen
> > > > patches in their kvm packaging, but they all seem to be changes to the
> > > > build/install process or security-related).
> > >
> > > Not to be pushy, but does anyone have any ideas on this, or can I
> > > provide any additional information? I'm afraid I'm a bit over my head
> > > when debugging kernel internals.
> >
> > Sorry, I meant to respond. This is more than likely a SCSI emulation
> > error rather than a kernel error. I've seen the error a couple of
> > times, but I don't have a fix for the issue yet as I don't have a
> > reliable way to reproduce the error. If you have an easy way to
> > reproduce the bug, I'll see if I can figure out a fix.
>
> I can reproduce this reliably when fscking a filesystem in a .vmdk I have.
> I can't give you the vmdk or a dump of the filesystem, but I can devote some
> time to troubleshoot this if you can guide me a little. If having the vmdk
> is really important, I might be able to sanitize it enough to send it to you
> (hopefully not making this bug unreproducible in the process).

I don't need the vmdk, but if there is some other repeatable process
that can trigger this for you, getting that will allow me to recreate
the issue myself. For example, installing Debian into a vmdk, reboot,
and then fsck'ing from inside the vm would trigger it. Finding some
sort of repeatable process that can trip the bug but without using any
of your specific data would be the best way to move forward with the
bug.

--
Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
ryanh@us.ibm.com