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?

Running with CONFIG_DMAR=n, system is stable.
Running with the exact same source but CONFIG_DMAR=y I get the
WARNING (see below) after about 36 hours of uptime (has varied from
about 24 to about 48):
Smolt profile: http://smolt.fedoraproject.org/show?uuid=pub_bb05c701-1e47-4b3c-9fab-54f520f39d79+
I'm also attaching dmesg.old (dmesg from the crash).

Subsequent to this the system watchdog reboots the system (it's hung).

Of interest: each and every time this has happened the system was
under heavy RX load (win7 backup to a cifs share hosted on this
server). Also, there is always a dhcp exchange of some sort
preceding the event.

It is possible that the event is re creatable without DMAR enabled,
but I have been unsuccessful in doing so.

It would be nice to check now if it's re-creatable without the dhcp
exchange yet, or at least dhcp through the switch and the router,
because I suspect there might be something more than a simple drop
on the switch that affects sky2 stability.

Jarek P.