[Pkg-xen-devel] Bug#919460: Bug#919460: xen: disk I/O problems on stretch PV guest restores after security update

[Hans van Kranenburg]

Hi Sergio,

On 1/16/19 10:31 AM, Sergio Gelato wrote:
> Source: xen Version: 4.8.5+shim4.10.2+xsa282-1+deb9u11
> 
> Yesterday I upgraded a test dom0 to this version (from
> 4.8.4+xsa273+shim4.10.1+xsa273-1+deb9u10; stretch amd64, Xeon E5430),
> then rebooted. Running domU's were saved and restored in the usual
> way. However, all PV domU's running stretch (both i386 and amd64, all
> kernel 4.9.130-2) lost write access to xvda on restore due to I/O
> errors. Sample kernel log attached. (/var/log/kern.log stopped
> recording entries, so I grabbed dmesg output to show what happened
> afterwards.)

Thanks for your report.

> and amd64). These were restored successfully.
> 
> In all cases, xvda is backed by an LVM logical volume local to the
> dom0.
> 
> After "reboot -f"ing some of the affected domUs (which made them
> functional again), I rebooted the dom0. This time all domUs were
> restored normally. (Of course those that still had their filesystems
> mounted read-only stayed that way.)
> 
> Is anyone else seeing this?

The usual questions here would be like "can you reproduce the issue"
etc... Because if you consistently can cause the problem to happen,
you're in a positition to start trying things.

The following is not an answer to your question, but a personal suggestion:

When speaking for myself, I've had major troubles with Linux 4.9 in the
dom0 causing all kinds of crashes when using live migrate (similar to
suspend/resume you're doing) and I've never been able to track them
down, they were never explained or fixed. blk-mq or general storage
related crashes where amongst them.

At this point, with the 4.19 kernel for buster already in pretty good
shape and in stretch-backports as well, I can recommend trying it out.

Hans