Re: xenbackendd error

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

On Fri, Oct 28, 2011 at 02:12:12PM +0200, Roger Pau Monné wrote:
> 2011/10/28 Manuel Bouyer <bouyer%antioche.eu.org@localhost>:
> > On Fri, Oct 28, 2011 at 01:44:33PM +0200, Roger Pau Monné wrote:
> >> 2011/10/28 Manuel Bouyer <bouyer%antioche.eu.org@localhost>:
> >> >
> >> > No, that's ok. This is fixed in HEAD, and there is a pending
> >> > pullup for netbsd-5:
> >> > http://releng.netbsd.org/cgi-bin/req-5.cgi?show=1682
> >>
> >> I thought this bug was introduced after the merge of the
> >> rmind-uvmplock branch, or at least I'm not able to reproduce it on
> >> previous kernels.
> >
> > I think we're talking about a different bug then. This one is
> > about keeping a pointer to a freed vnode in the backend driver.
> 
> Correct me if I'm wrong, but I think you are talking about this PR:
> http://gnats.netbsd.org/cgi-bin/query-pr-single.pl?number=45158 which
> I've submitted after the addition of the rmind-uvmplock branch, I
> never saw it happen before.

The symptoms are the same, but the bug I fixed in the backend has
nothing to do with rmind-uvmplock. It's a stale pointer being reused.

I started seeing this when doing tests with Xen 4.1 on a 8-cpu system.

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
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