Re: HEAD instability on Xen

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Mon, Nov 19, 2007 at 12:00:00PM +0100, Manuel Bouyer wrote:
> On Sun, Nov 18, 2007 at 11:12:38PM +0100, Manuel Bouyer wrote:
> > On Sun, Nov 18, 2007 at 10:08:03PM +0000, Andrew Doran wrote:
> > > 
> > > Acutally, it already has all the necessary changes. Is there a point where
> > > the kernel is entered with Xen that the direction flag might not be 
> > > cleared?
> > 
> > I'll have a look. Could it be a missing lock or splxx() in the pmap ?
> > 
> > > I can't see one. It is cleared for the copyout() in the traceback that you
> > > posted.
> > > 
> > > > I've also seen it in the pool code. It was always handling a trap after 
> > > > a
> > > > copyin or copyout though.
> > > 
> > > I did many hours of low-memory stress testing on the updated pool code
> > > before checking it in, so I don't believe that there is an (obvious) 
> > > problem
> > > there. It could be perhaps be related to the removal of the _CPU options.
> > 
> > No, I've seen it with a kernel from before the _CPU options removal
> > (the bouyer-xenamd64-base2 tag in src/sys). 
> 
> I've tracked it down to a change between 2007.11.05.10.25.03 and
> 2007.11.08.10.25.03 on HEAD. Here's another instance of the panic (with
> 2007.11.08.10.25.03):

It's between 2007.11.07.00.00.00 and (2007.11.07.02.00.00 +
xennetback_xenbus.c 1.19). 

-- 
Manuel Bouyer, LIP6, Universite Paris VI.           
Manuel.Bouyer%lip6.fr@localhost
     NetBSD: 26 ans d'experience feront toujours la difference
--