[em][panic] recursed on non-recursive mutex em0

[Jack Vogel]

On Wed, May 21, 2008 at 1:26 PM, Jack Vogel <jfvogel at gmail.com> wrote:
> On Wed, May 21, 2008 at 12:11 PM, Neil Hoggarth <neil at hoggarth.me.uk> wrote:
>> Hi Folks,
>>
>> I opened PR kern/122928 last month, describing my problems with Intel
>> PRO/1000 MT adaptor on 7-STABLE, with v6.7.3 of the em driver: every
>> so often the machine would get into a state where it would repeatedly
>> watchdog timeout the em0 interface, and the interface would stop
>> receiving packets.
>>
>> A few weeks ago I cvsupped a newer version of the 7-STABLE source
>> tree, after v6.9.0 of the em driver was MFCed. Since I started running
>> on the newer build watchdog timeouts appear to be followed by a system
>> panic rather than the freezing up of the interface.  I have no hard
>> evidence but it "feels like" the panics are happening under the same
>> sort of circumstance that was previously triggering my watchdog
>> problem (basically network activity combined with CPU load). A similar
>> observation was made by Yani Karydis on the freebsd-stable mailing
>> list earlier in the month:
>>
>> http://lists.freebsd.org/pipermail/freebsd-stable/2008-May/042311.html
>>
>> I've now got a serial console set up, and I'm running a kernel with
>> DDB support compiled in. I managed to get the information below out of
>> the most recent panic. Is anyone able to use this to debug the
>> situation? What else might I try to gather useful information?
>
> This is a helpful start, I'll stare at the code and see... sounds like some
> rx lock design issue.

OPPS, I think I found the problem, look for a delta on if_em.c shortly.

Let me know if this fixes your problem.

Jack