Re: [Xen-devel] domains not shutting down properly - theproblemisback again

[Keir Fraser <keir.fraser@xxxxxxxxxxxxx>]

On 02/01/2009 10:11, "James Harper" <james.harper@xxxxxxxxxxxxxxxx> wrote:

>> xenstored will not auto-connect to any domain. So since it holds no
>> resources of the domU, it won't impede the domU's destruction.
> 
> Even a domain I create subsequent to restarting xenstored & xend? 'xm
> console' doesn't work in that case so I'm guessing not.

No. I'd be a bit surprised if you could create a domain without a wotrking
dom0 ring connection to xenstored though.

> I have previously logged xenstored_domain.c:domain_cleanup() - it never
> gets called during the domain crashing or being shut down. I think the
> action of creating another domain (or an explicit 'xm destroy') results
> in domain_cleanup() getting called somewhere along the way, which mostly
> cleans up the domain but obviously leaves a few pages and an event
> channel lying around (as revealed by 'xm debug q' and 'lsevtchn').

As long as domain_cleanup() gets called at some point it should see the
dying domU has dominfo.dying and then release resources.

> I guess I'll start adding some logs to domain.c...

Good idea. Maybe something is going wrong in domain_kill(). That will be
called by the DOMCTL_destroydomain hypercall, which should be triggered by
'xm destroy'. Note the hypercall is preemptable, requiring a loop on EAGAIN
in libxenctrl, to make sure it completes its work. The notification on
VIRQ_DOM_EXC is near the end of the function.

 -- Keir



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