Re: [Xen-API] XCP 1.0-beta: md on dom0 kernel causes kernel oops

[Daniel Stodden <daniel.stodden@xxxxxxxxxx>]

On Mon, 2010-12-06 at 07:40 -0500, Tomoe Sugihara wrote:
> On 12/03/2010 08:03 AM, Tomoe Sugihara wrote:
> > On 12/02/2010 05:50 PM, Simon Rowe wrote:
> >> On Wednesday 01 Dec 2010 23:03:48 Tomoe Sugihara wrote:
> >>
> >>> I tried the following two and both ended up with Oops.
> >>>
> >>> 1. just two regular HDDs --- /dev/sdc and /dev/sde or whatever.
> >>>
> >>>       Here's how I reproduced just now.Very soon after dd, kernel panics.
> >>>
> >>>        $ mdadm --create /dev/md0 --level=mirror --raid-devices=2 /dev/sdc
> >>> /dev/sde mdadm: /dev/sdc appears to be part of a raid array:
> >>>            level=raid1 devices=2 ctime=Mon Nov 29 15:52:53 2010
> >>>        mdadm: /dev/sde appears to be part of a raid array:
> >>>            level=raid1 devices=2 ctime=Mon Nov 29 09:34:34 2010
> >>>        Continue creating array? y
> >>>        mdadm: array /dev/md0 started.
> >>>        $ dd if=/dev/zero of=/dev/md0 bs=1M
> >>>
> >>>
> >>>
> >>> 2. dm linear devices which are on top of iscsi
> >>>
> >>>      mdadm --create /dev/mirror/000008bc --auto=md --bitmap=internal
> >>> --metadata=0 --run --bitmap-chunk=65536 --delay=5   --level=1
> >>> --assume-clean --raid-devices=3 /dev/mapper/00000001-00000003
> >>> /dev/mapper/00000002-000002d7 /dev/mapper/00000003-0000050a
> >>>
> >>>       Interestingly, his doesn't cause kernel panic; similar stack trace
> >>> shows up in dmsg and mdadm stalls.
> >>
> >> We don't support (and therefore test) software RAID in XenServer. I'll 
> >> some of
> >> our kernel guys if there's anything obvious.
> >>
> >>    Simon
> >>
> >
> > Could you see the email that I reported the issue? Here's a link to the 
> > post:
> > http://www.mail-archive.com/xen-api@xxxxxxxxxxxxxxxxxxx/msg02151.html
> >
> > As I said, the issue is introduced by dom0 custom patch, which I put a link 
> > to the repository below,
> > therefor it is not there in vanilla kernel.
> >
> > http://xenbits.xen.org/XCP/linux-2.6.32.pq.hg?diff/2d68a42120cf/blktap2-ioc.diff
> >
> > I would really want it to be addressed not only for our SM backend plugin 
> > but also for the sake
> > of removing the vulnerability.
> 
> Hi,
> 
> We would really like this to be addressed so we can test
> XCP 1.0 beta with our SM backend driver.
> 
> I found the author and the log for the patch that introduces the oops from 
> the following link.
> http://xenbits.xen.org/XCP/linux-2.6.32.pq.hg?annotate/2d68a42120cf/blktap2-ioc.diff
> 
> I didn't get what it is for, but I hope the author may be able to help this 
> fixed.

Yeah, looks like this queue got tagged for XCP on a quite unfortunate
edge, indeed. The patch series has long been fixed since then, but
merged a little further on trunk, so I can't just offer you a
replacement for the -ioc diff. 

One could replace the entire blktap2-series, or maybe there's a bigger
update already in the make (?).

Cheers,
Daniel


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