Re: Fatal page fault in cbq_enqueue()

[Paul Ripke <stix%stix.id.au@localhost>]

On Wed, Mar 08, 2017 at 08:53:56PM -0500, Christos Zoulas wrote:
> On Mar 9, 12:16pm, stix%stix.id.au@localhost (Paul Ripke) wrote:
> -- Subject: Re: Fatal page fault in cbq_enqueue()
> 
> | > > Index: altq_classq.h
> | > > ===================================================================
> | > > RCS file: /cvsroot/src/sys/altq/altq_classq.h,v
> | > > retrieving revision 1.7
> | > > diff -u -u -r1.7 altq_classq.h
> | > > --- altq_classq.h	12 Oct 2006 19:59:08 -0000	1.7
> | > > +++ altq_classq.h	27 Jan 2017 18:10:12 -0000
> | > > @@ -108,9 +108,9 @@
> | > >  {
> | > >  	struct mbuf  *m, *m0;
> | > >  
> | > > -	if ((m = qtail(q)) == NULL)
> | > > +	if ((m = qtail(q)) == NULL || (m0 = m->m_nextpkt) == NULL)
> | > >  		return (NULL);
> | > > -	if ((m0 = m->m_nextpkt) != m)
> | > > +	if (m0 != m)
> | > >  		m->m_nextpkt = m0->m_nextpkt;
> | > >  	else
> | > >  		qtail(q) = NULL;
> | > 
> | > Indeed... Well, we'll see how it goes, I'm running with that now. I've
> | > had one crash since, so a couple of weeks might be enough to have some
> | > idea.
> | 
> | Pity. Crashed elsewhere. I think there's a definite race in altq somewhere.
> 
> So it took how many days?

Booted with that patch around Jan 28. I think I've had a couple of
silent reboots since, followed by:

Mar  3 10:45:30 slave /netbsd: panic: _rmc_wrr_dequeue_next
Mar  3 10:47:42 slave /netbsd: panic: _rmc_wrr_dequeue_next
Mar  9 11:52:03 slave /netbsd: panic: _rmc_wrr_dequeue_next

That's a remarkably tight cluster of crashes.

-- 
Paul Ripke
"Great minds discuss ideas, average minds discuss events, small minds
 discuss people."
-- Disputed: Often attributed to Eleanor Roosevelt. 1948.