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

[Tomoe Sugihara <sugihara@xxxxxxxxxxxxx>]

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.


Best,
Tomoe

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