[Xen-users] Experiencing kernel panic with SSH + LVM + Xen + significant amounts of data

[Peter Selby <peter@xxxxxxxx>]

Hi all,

I'm running into a kernel panic with Xen, under fairly specific
circumstances. I'll post it here first, and follow up on xen-devel if
it looks like it's a Xen bug.

After some experimentation, it seems like the panic occurs under the
following circumstances:

1) A significant amount of data is being moved

2) ...Onto (or off of?) an LVM partition

3) ...With SSH being involved somehow?

4) ...On Xen.

Originally, I was trying to move a filesystem over the network via "dd
if=... | ssh dd of=...", onto an LVM partition. The filesystem was
20G, and it repeatably crashed, usually after >25% transferred.

I've also tried scp'ing files, using dd to transfer files,
transferring the 20G FS to /dev/null, moving data OFF the host in
question, etc. None of these triggered a panic.

Moving large files on the host itself doesn't trigger a
crash. However, piping data to an LVM partition (and in one case,
piping from LVM to /dev/null) has triggered a crash, though the panic
seems to occur simultaneously with an SSH login when it's
happened. Minus an SSH login, I've successfully and repeatably moved
data from LVM => LVM, LVM => null, yes => LVM, without a crash (logged
in via SSH the whole time, I should add...there seems to be something
about logins specifically)

The system has ended up in a bad state more than once, too, which
complicates things. It's possible that the crash triggered by moving
OFF of LVM to /dev/null was the result of a bad state triggered
earlier, because I wasn't able to reproduce it.

No such issues occur if I'm not running Xen, which seems to rule out
HW failure. To be clear, the host in question is the hypervisor, and
the panics occur regardless of whether VMs are running.

Version info:

Essentially, it's a fully up-to-date Ubuntu 12.04 system.

HW - HP ProLiant DL145 G2/K85NL (rackmount)

Xen - 4.1.2-2ubuntu2.6

LVM:
  LVM version:     2.02.66(2) (2010-05-20)
  Library version: 1.02.48 (2010-05-20)
  Driver version:  4.22.0

SSH:
  OpenSSH_5.9p1 Debian-5ubuntu1, OpenSSL 1.0.1 14 Mar 2012

Kernel - 3.2.0-39-generic

I can provide more info on request.

I've also attached a sample kernel panic. This one's a little old, but
the crashes don't always dump to syslog, and the symptoms haven't
changed.

Thanks!

Peter

Attachment: kernelpanic.txt
Description: Text document

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