spin lock sched lock held for > 5 seconds

Hi,

got the following panic overnight running with all debugging options on
(WITNESS, MUTEX_DEBUG, DIAGNOSTIC, INVARIANTS; WITNESS_SKIPSPIN off):

panic: spin lock sched lock held by 0xc658e130 for > 5 seconds
cpuid = 0; lapic.id = 00000000
Stack backtrace:
backtrace(c031d030,0,c031c4c5,df0dab8c,100) at backtrace+0x17
panic(c031c4c5,c031c62e,c658e130,c036f160,18b) at panic+0x13d
_mtx_lock_spin(c036f160,2,c031a229,18b,c21b2ab0) at _mtx_lock_spin+0x83
_mtx_lock_spin_flags(c036f160,2,c031a229,18b,df0dac0c) at
_mtx_lock_spin_flags+0xb9
statclock(df0dac00,df0dac44,c02d8a9c,0,c2198d00) at statclock+0x39
rtcintr(0) at rtcintr+0x4f
Xfastunpend8(df0dacb8,c02d1f05,8,608,c0372e60) at Xfastunpend8+0x1c
call_fast_unpend(8,608,c0372e60,ffc00034,0) at call_fast_unpend+0xd
i386_unpend(c036f160,c21b0790,df0dacd0,c01b1ae0,df0dacec) at
i386_unpend+0x8d
cpu_unpend(df0dacec,c01a2534,c036f160,1,c031c2e2) at cpu_unpend+0x2d
critical_exit(c036f160,1,c031c2e2,1bc,1) at critical_exit+0x2d
_mtx_unlock_spin_flags(c036f160,0,c031ac9f,7c,c21b2ab0) at
_mtx_unlock_spin_flags+0xbb
idle_proc(0,df0dad48,c031ab89,312,c21b2ab0) at idle_proc+0xb0
fork_exit(c0199972,0,df0dad48) at fork_exit+0xc3
fork_trampoline() at fork_trampoline+0x1a
--- trap 0x1, eip = 0, esp = 0xdf0dad7c, ebp = 0 ---
Debugger("panic")
timeout stopping cpus
Stopped at      Debugger+0x4f:  xchgl   %ebx,in_Debugger.0
db>

The machine is still in ddb, let me know if I can provide additional info.

Lars
-- 
Lars Eggert <larse_at_isi.edu>           USC Information Sciences Institute