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RE: [Xen-devel] blocking Xen 3.X production use: soft lockup bugs

To: "Steve Traugott" <stevegt@xxxxxxxxxxxxx>, "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject: RE: [Xen-devel] blocking Xen 3.X production use: soft lockup bugs
From: "Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>
Date: Wed, 2 Aug 2006 23:25:45 +0100
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Thread-topic: [Xen-devel] blocking Xen 3.X production use: soft lockup bugs
> The problem (or something that looks identical) is described in
> several tickets, status currently NEW or REOPENED, no clear
> resolution:
> http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=543
> http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=690
> http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=697
> http://bugzilla.xensource.com/bugzilla/show_bug.cgi?id=705

There's very little to go on here. Two of the bugs are actually the same
guy. One of the others is x86_64 the other two are 32b. 

The only thing in common about the stack traces is that networking
functions seem to feature.

Taking a wild guess, are you doing some kind of unusual networking setup
involving iptables rules?

> Do we have any consensus that this bug is fixed at all in
> xen-3.0-testing, or even unstable?  Is anyone who was hitting soft
> lockups in testing *not* hitting them any more on the same hardware?
> If so, what changeset are you on now?

Soft lockups could be due to a huge variety of causes. It's unlikely to
be a hardware issue, and since the problems seem to be experienced by a
very small number of users my guess would be that it's configuration
dependent, most likely networking.

> If anyone needs any more information, just let me know.  As usual, if
> anyone wants login and console server access to one of these boxes to
> chase this down, I'm more than happy to provide that.

Having a really detailed bug report would really be the best way of

When this happens, does it just effect one guest? What's the stack
trace? How many VCPUs has the guest got? Is the guest completely hosed
or is it still pingable? What about guest console echo? What about 'xm
sysreq'? Looking in dom0, are you still seeing packets go to/from the
associated VIF? How many network interfaces has the guest got? What's
the precise networking setup in dom0? Can you come up with a recipe for
reproduction, ideally with a single guest? 


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