Subject: Re: 2.6.19-rc6 : Spontaneous reboots, stack overflows - seems to implicate xfs, scsi, networking, SMP

From: David Chinner <[email-masked]>
Date: Fri, 24 Nov 2006 13:05:08 +1100

On Fri, Nov 24, 2006 at 02:08:53AM +0100, Jesper Juhl wrote:
> On 24/11/06, David Chinner <[email-masked]> wrote:
> >On Thu, Nov 23, 2006 at 07:37:00PM +0100, Arjan van de Ven wrote:
> >> On Thu, 2006-11-23 at 14:16 +0100, Ingo Oeser wrote:
> >> > Hi there,
> >> >
> >> > David Chinner schrieb:
> >> > > If the softirqs were run on a different stack, then a lot of these
> >>
> >> softirqs DO run on their own stack!
> >
> >So they run on a separate stack for 4k stacks on x86?
> 
> Yes, with 4K stacks there's sepperate IRQ stack.

Ok, thanks.

> >They don't run on a separate stack for 8k stacks on x86 -
> >Jesper's traces show that - so this may indicate an issue
> >with the methodology used to generate the stack overflow
> >traces inteh first place. i.e. if 4k stacks use a separate
> >stack, then most of the reported overflows are spurious
> >and would not normally occur on 4k stack systems..
> >
> 
> Well, some of the traces show that we were down to ~3K stack free with
> 8K stacks, so ~5K used. Even with 4K stacks and sepperate stack for
> IRQs we will still be uncomfortably close to the edge in those cases.

Sure - i didn't say there wasn't a problem - more just indicating
that most of the traces would not have happened on a 4k stack box so
it's harder to tell which of the traces you posted would actually
lead to an overflow.

Cheers,

Dave.
-- 
Dave Chinner
Principal Engineer
SGI Australian Software Group