Finally a panic while I'm not in X... Today's CVS on i386:

simple_lock: uninitialized lock
lock: 0xce707ef8, currently at: ../../../../kern/kern_synch.c:184
uvm_fault(0xc05c3da0, 0xdeadb000, 1) -> 0xe
kernel: supervisor trap page fault, code=0
Stopped in pid 0.17 (system) at netbsd:strlen+0x8:    cmpb  $0,0(%eax)
 
strlen+0x8
vsnprintf+0x42
lock_printf(c0531a16,deadbeef,ffffbeef,b8,c) lock_printf+0x5f
_simple_lock+0x8c
ltsleep+0x18f
acquire_0xb0
_lockmgr+0x507
ufs_lock+0x4f
VOP_LOCK+0x25
vn_lock+0x9f
vrele+0x130
vget_0x90
ffs_sync_0xde
sync_fsync+0xaa
VOP_FSYNC+0x49 
sched_sync+0xf5
db> show lock  
Sorry, no record of a lock with address 0xc0492fd0 found.
db> sync

Mutex error: lockdebug_wantlock: locking against myself
...
Turnstile chain at 0xc05e3960
=> No active turnstile for this lock.

(I can only guess that the other box with a kernel built today is
freezing for similar reasons but I'm always in X when it happens.)

Cheers,

Patrick