Re: hibernation hangs with ATA errors (lockup_detector bug)

[Frederic Weisbecker <fweisbec@gmail.com>]

On Wed, Jun 02, 2010 at 09:13:40PM +0200, Frederic Weisbecker wrote:
> On Wed, Jun 02, 2010 at 02:44:59PM -0400, Don Zickus wrote:
> > On Tue, Jun 01, 2010 at 04:46:28PM +0200, Jiri Slaby wrote:
> > > On 06/01/2010 03:50 PM, Don Zickus wrote:
> > > > On Mon, May 31, 2010 at 04:22:00PM +0200, Jiri Slaby wrote:
> > > >> Hi,
> > > >>
> > > >> with -next I get the following errors while trying to hibernate in
> > > >> qemu-kvm after the image is stored on disk:
> > > > 
> > > > Is this the host that is hibernating or the guest?
> > > 
> > > Guest.
> > > 
> > > > KVM guests don't emulate the performance counters, so the nmi piece
> > > > shouldn't be functioning and the soft lockup piece just sits on top of an
> > > > hrtimer, so off the top of my head it is hard to imagine it intefering
> > > > with a sata driver.
> > > > 
> > > > I'll need your whole boot up log to see how the lockup detector
> > > > initialized itself.
> > 
> > Ok, so I found out what is causing the problem, not entirely sure why or
> > what the right fix is, but this patch should do the trick.
> > 
> > This is probably one of those fixing the symptoms but not the problem patch,
> > but I don't know enough about suspend/resume to understand what the real
> > problem is.
> 
> 
> So the problem is that we stop the cpu hotplug notifying, I guess this prevents
> some ata callbacks to execute in the cpu hotplug notifier and then provoke this
> crash.


(Adding more people in Cc)


But I'm eventually surprised about this: stopping the cpu hotplug callbacks
prevents some ATA resume callbacks to execute.

Does that mean some ata resume path are done from a cpu hotplug notifier?
That looks weird.