NULL pointer dereference panic

I got the following panic is a fresh -current.  Unfortunately, it didn't
do a crash dump - I'm not sure why.  Has anyone else seen this?

Fatal trap 12: page fault while in kernel mode
fault virtual address    = 0x2c
fault code               = supervisor read, page not present
instruction pointer      = 0x20:0xc052cf96
stack pointer            = 0x28:0xd6690970
frame pointer            = 0x28:0xd6690990
code segment             = base 0x0, limit 0xfffff, type 0x1b
= DPL 0, pres 1, def32 1, gran 1
processor eflags = interrupt enabled, resume, IOPL = 0
current process          = 97180 (script)
trap number              = 12
panic: page fault
KDB: stack backtrace:
kdb_backtrace(c07008a8,c076ac80,c06eb1ad,d6690844,100,...) at kdb_backtrace+0x2e
panic(c06eb1ad,c0702b35,d6690930,1,1,...) at panic+0xb7
trap_fatal(d6690930,2c,c071dc0f,2fd,c2b6f6c0,...) at trap_fatal+0x30e
trap_pfault(d6690930,0,2c,c054f7e1,2c,...) at trap_pfault+0x1ba
trap(8,28,28,c0709faa,1a3,...) at trap+0x461
calltrap() at calltrap+0x5
--- trap 0xc, eip = 0xc052cf96, esp = 0xd6690970, ebp = 0xd6690990 ---
_mtx_lock_flags(24,0,c0709faa,1a3,0,...) at _mtx_lock_flags+0x46
vfs_ref(0,d66909f8,0,d66909dc,c06d4f68,...) at vfs_ref+0x32
vop_stdgetwritemount(d66909f8,c076ea74,d66909f0,d6690a2c,d6690a14,...) at vop_stdgetwritemount+0x1d
VOP_GETWRITEMOUNT_APV(c073df20,d66909f8,c07b4988,c06fe125,d6690a0c,...) at VOP_GETWRITEMOUNT_APV+0xa8
vn_start_write(c4251000,d6690a2c,1,2,c0701fa5,...) at vn_start_write+0x37
vn_close(c4251000,3,c2f37780,c2b6f6c0,6b5,...) at vn_close+0x65
vn_closefile(c370c750,c2b6f6c0,d6690af0,c0512cce,c370c750,...) at vn_closefile+0xe9
devfs_close_f(c370c750,c2b6f6c0,c06fca41,876,c370c750,...) at devfs_close_f+0x19
fdrop_locked(c370c750,c2b6f6c0,c06fca41,861) at fdrop_locked+0xbe
fdrop(c370c750,c2b6f6c0,d6690b38,c0567d6f,c076ea74,0,c07046e5,6b5,c07b4a6c,d6690b68,0,c07b4a68,d6690b64,c0566bba,0,c394872c,246,c0744d24,c394872c,661,c06fca41,d6690b8c,c052d0f2,c394872c,1,c06ff4e5,13

closef(c370c750,c2b6f6c0,c06fca41,661,c07b4a68,...) at closef+0x427
fdfree(c2b6f6c0,0,c06fd2c3,106,d6690c50,...) at fdfree+0x5c6
exit1(c2b6f6c0,0,d6690d30,c06bf073,c2b6f6c0,...) at exit1+0x57b
sys_exit(c2b6f6c0,d6690d04,4,c2b6f6c0,c33f0000,...) at sys_exit+0x1d
syscall(3b,3b,3b,1,0,...) at syscall+0x2e3
Xint0x80_syscall() at Xint0x80_syscall+0x1f
--- syscall (1, FreeBSD ELF32, sys_exit), eip = 0x281012fb, esp = 0xbfbfe1ec, ebp = 0xbfbfe1f8 ---

-- 
Peter Jeremy