panic: mutex em1 not owned at /usr/src/sys/dev/em/if_em.c:1608

With today's current.

I got an panic when playing with net/freevrrpd.  I forgot to specify
$dumpdev in /etc/rc.conf on this new test box, so I cannot get kernel
core at this time...


----- console
Dec  5 12:41:15 soia freevrrpd[36220]: interface em1 is alive again, reactivate it on VRRP
em1: watchdog timeout -- resetting
panic: mutex em1 not owned at /usr/src/sys/dev/em/if_em.c:1608
cpuid = 0; 
Debugger("panic")
Stopped at      Debugger+0x55:  xchgl   %ebx,in_Debugger.0
db> trace
Debugger(c074cea6,0,c074c48f,e1fc5c48,100) at Debugger+0x55
panic(c074c48f,c692d200,c073f433,648,c6928000) at panic+0x156
_mtx_assert(c6928354,1,c073f433,648,c6928000) at _mtx_assert+0xec
em_stop(c6928000,1,c6928000,0,e1fc5cb0) at em_stop+0x32
em_watchdog(c6928000,0,c07554b3,4bd,7) at em_watchdog+0x57
if_slowtimo(0,0,c074df78,d8,1) at if_slowtimo+0x67
softclock(0,0,c074abe2,23a,c68de000) at softclock+0x1b8
ithread_loop(c687bd00,e1fc5d48,c074aa48,311,0) at ithread_loop+0x192
fork_exit(c0545340,c687bd00,e1fc5d48) at fork_exit+0xb4
fork_trampoline() at fork_trampoline+0x8
--- trap 0x1, eip = 0, esp = 0xe1fc5d7c, ebp = 0 ---
db> show locks
exclusive sleep mutex ifnet r = 0 (0xc07f0800) locked _at_ /usr/src/sys/net/if.c:1213
exclusive sleep mutex Giant r = 0 (0xc07c6a20) locked _at_ /usr/src/sys/kern/kern_timeout.c:216
-----


-- 
Jun Kuriyama <kuriyama_at_imgsrc.co.jp> // IMG SRC, Inc.
             <kuriyama_at_FreeBSD.org> // FreeBSD Project