sysctl -a causes kernel trap 12

[Konstantin Belousov]

On Mon, Jan 07, 2013 at 03:54:23PM -0800, Xin Li wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA256
> 
> Hi,
> 
> I've recently (by mid-December I think) noticed that sysctl -a can
> sometimes cause kernel trap 12.  Tried enabling INVARIANTS and the
> problem mysteriously disappeared.  After some experiments on this, it
> seems that this can be triggered by sysctl -a but the system have an 1
> in 10 chance to survive.  When INVARIANTS is enabled however, I can
> not trigger the panic.  "sysctl hw" triggers the panic sometimes, but
> not always.
> 
> Do anybody have clue on this?  The system hangs hard when it panics so
> kernel debugger won't work.  When it panics, the fault instruction
> pointer is always 0x20:0xffffffff808d61c9, which is
> sys/kern/subr_turnstile.c:297:
> 
> > /* Resort td on the list if needed. */ if
> > (!turnstile_adjust_thread(ts, td)) { mtx_unlock_spin(&ts->ts_lock);
> > // 297 // return; }
> 
> This sounds like a race condition but I haven't yet able to track it
> down...

Could you try to isolate the sub-leaf under hw which causes the panic ?
Just shot in the dark, do you have Intel GPU gemified driver loaded ?
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 834 bytes
Desc: not available
URL: <http://lists.freebsd.org/pipermail/freebsd-current/attachments/20130108/c5358ee3/attachment.sig>