7.1-PRELEASE sporadically panicking with fatal trap 12

John Baldwin jhb at freebsd.org
Mon Sep 29 15:38:47 UTC 2008

On Saturday 27 September 2008 02:37:55 pm John L. Templer wrote:
> I'm running 7.1-PRERELEASE, with /usr/src and /usr/ports last csup-ed 
> just a few days ago.  After being up for about a day or so the system 
> will panic because of a page fault.  I'm not completely sure, but it 
> seems that the system is more stable when gdm and gnome are disabled in 
> rc.conf.  At least it stayed up for several days when I did that.
> I've run memtest several times, so I'm pretty confident it's not a 
> memory problem.  Also the stack trace is always the same, so I'm 
> thinking it's not hardware related.
> I've attached a stack trace from kgdb, and the output from dmesg.  I'd 
> appreciate any help you could give me with this.

Generally when I see this panic (at this source line in mtx_lock() and with an 
offset of 0x188 or 0x18c), it is because the mutex is destroyed (mtx_lock == 

In this case since you got it in a task, I'm guessing ata destroyed a 
structure w/o draining the task, so the task executed after the structure 
containing the mutex was destroyed.

John Baldwin

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