LOR on reboot

[Ke Sun]

Hi current,

I have FreeBSD 10.0-CURRENT #5 r254404 on my laptop. During reboot,
I get the following LOR. Could someone please fix this?

Thanks!
Ke Sun

Syncing disks, vnodes remaining...0 0 0 0 0 0 done
All buffers synced.
lock order reversal:
 1st 0xfffffe00094bd5f0 zfs (zfs) @ /usr/src/sys/kern/vfs_mount.c:1237
  2nd 0xfffffe000903b418 devfs (devfs) @ /usr/src/sys/ufs/ffs/ffs_vfsops.c:1411
  KDB: stack backtrace:
  db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xffffff81a7582470
  kdb_backtrace() at kdb_backtrace+0x39/frame 0xffffff81a7582520
  witness_checkorder() at witness_checkorder+0xd4f/frame 0xffffff81a75825b0
  __lockmgr_args() at __lockmgr_args+0x6f2/frame 0xffffff81a75826e0
  vop_stdlock() at vop_stdlock+0x3c/frame 0xffffff81a7582700
  VOP_LOCK1_APV() at VOP_LOCK1_APV+0xf5/frame 0xffffff81a7582730
  _vn_lock() at _vn_lock+0xab/frame 0xffffff81a75827a0
  ffs_flushfiles() at ffs_flushfiles+0x88/frame 0xffffff81a7582800
  ffs_unmount() at ffs_unmount+0x162/frame 0xffffff81a7582860
  dounmount() at dounmount+0x39e/frame 0xffffff81a75828e0
  vfs_unmountall() at vfs_unmountall+0x61/frame 0xffffff81a7582910
  kern_reboot() at kern_reboot+0x548/frame 0xffffff81a7582980
  sys_reboot() at sys_reboot+0x58/frame 0xffffff81a75829a0
  amd64_syscall() at amd64_syscall+0x265/frame 0xffffff81a7582ab0
  Xfast_syscall() at Xfast_syscall+0xfb/frame 0xffffff81a7582ab0
  --- syscall (55, FreeBSD ELF64, sys_reboot), rip = 0x80085f5ec, rsp =
  0x7fffffffd9b8, rbp = 0x7fffffffdb20 ---