Re: 2.6.17-rc5-mm1

["Martin J. Bligh" <mbligh@mbligh.org>]

Andrew Morton wrote:
> "Martin J. Bligh" <mbligh@mbligh.org> wrote:
>
> > Andrew Morton wrote:
> >
> > > Martin Bligh <mbligh@google.com> wrote:
> > >
> > >
> > > > The x86_65 panic in LTP has changed a bit. Looks more useful now.
> > > > Possibly just unrelated new stuff. Possibly we got lucky.
> > >
> > > What are you doing to make this happen?
> >
> > runalltests on LTP
>
>
> We have to get to the bottom of this - there's a shadow over about 500
> patches and we don't know which.

We did do one chop, and concluded it wasn't the x86_64 patches.

> iirc I tried to reproduce this a couple of weeks back and failed.

It looks like a different panic to me. It was a double-fault before.

> Are you able to narrow it down to a particular LTP test?  It was mtest01 or
> something like that?  Perhaps we can identify a particular command line
> which triggers the fault in a standalone fashion?

I can't do much from here - it's running on an IBM machine. Have to beg
Andy, or one of the other IBMers, for help.

> And why can't I make it happen?  Perhaps it's a memory initialisation
> problem, and it only happens to hit in that stage of LTP because that's
> when you started doing page reclaim, or something? 

It consistently happens on -mm, and not mainline, flicking back and 
forth over time. So if you mean h/w mem init, I don't think so. if you
mena some patch in -mm, then yes.

>  Perhaps just try putting a heap of memory pressure on the machine, 
> see what that does?

Yes, the other stuff might not be swapping.

> Being unable to reproduce it and not having a theory to go on leaves us
> kinda stuck.  Help, please?

Yeah, we have a sniff-testing mechanism that works well. However,
drill-down still requires significant amounts of human intervention.
The next gen of stuff should help do more intelligent stuff, but we're
kind of stuck with human-ness for now.

M.

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