Re: Hang: 2.6.32.4 sky2/DMAR (was [PATCH] sky2: Fix WARNING: atlib/dma-debug.c:902 check_sync)

[Michael Breuer]

On 1/22/2010 6:06 PM, Jarek Poplawski wrote:
> On Fri, Jan 22, 2010 at 05:14:58PM -0500, Michael Breuer wrote:
>    
> > On 1/22/2010 4:53 PM, Jarek Poplawski wrote:
> >      
> > > On Fri, Jan 22, 2010 at 01:01:15PM -0500, Michael Breuer wrote:
> > >        
> > > > Kernel 2.6.32.4 (git) with the following patches applied:
> > > >
> > > > af_packet.c (tpacket_snd version 3)
> > > > sky2.c pskb_may_pull
> > > > sky2 fix WARNING at lib/dma-debug.c check_sync
> > > >          
> > > I guess, you meant the "sky2.c receive_copy" patch which you tested
> > > earlier, or at least you managed to crash DMAR with that patch
> > > before crashing it with Stephen's "lib/dma-debug.c check_sync" patch,
> > > right?
> > >
> > >        
> > Yes - sorry, correct - all three patches were in the last run.
> > Previously, I've encountered the crash without these patches.
> >      
> OK, thanks for testing - it's really very helpful, and supports
> David's opinion that dmar is a different problem.
> ...
>    
> > Not sure I can do that. Note that based on the log messages, there
> > were no errors/dropped packets involving dhcp. Moving the dhcp
> > server off of the affected machine is not trivial. The dhcp
> > correlation is based on logged messages preceding each crash. I
> > cannot confirm that they're related, however it's really suspicious.
> > If it helps, HP replaced my unmanaged switch with a managed one so I
> > can see whether there were any switch events logged the next time I
> > have a crash.
> >
> > At this point, it seems the following is required to trigger the crash:
> > 1) Uptime of 24-36 hours
> > 2) High RX load on server (cifs traffic is what I've triggered it with).
> > 3) Normal DHCP traffic.
> >      
> Do you mean you got these crashes with the new switch too, and this
> switch doesn't drop DHCP at all? (Otherwise, let's try this switch
> first.)
>
> Jarek P.
>    
Nope - just got the new switch. Crash was old switch. That said, I don't 
think (based on the log messages) that the dhcpoffer packet drop was 
happening prior to the crash. I also can't fathom why a DHCPOFFER packet 
dropped after leaving the server would have any bearing on the issue.
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