Re: [Xen-users] regession: domU locks up with kernel 4.1.10

[Ian Campbell <ian.campbell@xxxxxxxxxx>]

On Sun, 2015-10-11 at 22:51 +0200, Sven KÃhler wrote:
> Hi,
> 
> while 4.1.8 runs solid for months, 4.1.10 locks up minutes or even
> seconds after domU has booted. The log is full of messages like
> 
> INFO: rcu_sched detected stalls on CPUs/tasks: { 0}
> 
> and xl top shows the corresponding domU stuck at above 100-104% CPU
> usage. Also, the domU becomes unresponsive as far as network I/O is
> concerned.
> 
> I'm using the kernel sources from kernel.org without any patches. I use
> the same .config for 4.1.8 and 4.1.10.
> 
> git diff --stat didn't show any suspecious xen related changes, so I'm
> wondering what's going on. Is anybody else seeing this?

FWIW the Xen Project osstest automated test has been running on 4.1.10 and
isn't seeing anything like this. It's seeing an unrelated and apparently
machine specific failure to migrate an HVM guest, but the other stuff is wo
rking ok.

Is it the dom0 or the domU which is locking up? Which are you changing?

The rcu_sched stall message is a generic symptom of lots of potential
issues (it just means some CPU got stuck), the surrounding logs would
likely contain more information. It is best to post the whole thing.

It's possible that some generic or arch/x86 change has interacted badly
with the Xen support, or that this is e.g. a driver issue.

4.1.8 to 4.1.10 is only 190 commits, which is only a handful of steps with
git bisect, so it would be well worth trying that.

Ian.


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