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

From: Jarek Poplawski
Date: Fri Jan 22 2010 - 18:06:18 EST

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 (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

Jarek P.
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