panic: Bad tailq NEXT (kqueue issue ?)

[Francois Tigeot]

On Thu, Sep 02, 2010 at 12:27:39PM +0200, Francois Tigeot wrote:
> I have been running the latest -master for a few hours on my main
> desktop box.
> It has just now freezed under X11 and rebooted automatically.
> 
> On the next boot, the system was able to save a core dump:
> 
> panic: Bad tailq NEXT(0xfffffffe5550e190->tqh_last) != NULL
> 
> Relevant files are available here:
> http://www.wolfpond.org/crash.dfly/

I believe this bug is a consequence of the recent kqueue work.

The panic originates at line 600 of sys/kern/kern_event.c

The relevant line is part of kern_event():
	TAILQ_INSERT_TAIL(&kq->kq_knpend, &marker, kn_tqe);

This function is marked MPSAFE; I'm running a SMP kernel on a Core 2 Duo CPU.

So far, this panic occurs every few hours with the latest kernel.

-- 
Francois Tigeot