CURRENT r293712 lock order reversal

[Baho Utot]

I get the following when I unmount a thumb drive

Here is how I created the system......

I installed FreeBSD-10.2 and then updated it to CURRENT by the handbook.

I then rebuilt the whole system by using release.sh so I would have a 
clean "install" media.

I then copied (dd) the memstick image to a thumb drive and booted to it.
I then installed "CURRENT" from the memstick overwriting the system ie 
"clean install"

This is from dmesg:

FreeBSD is a registered trademark of The FreeBSD Foundation.
FreeBSD 11.0-CURRENT #0 r293712: Wed Jan 13 01:02:51 UTC 2016
     root at dell.bildanet.com:/usr/obj/usr/src/sys/GENERIC amd64
FreeBSD clang version 3.7.1 (tags/RELEASE_371/final 255217) 20151225
WARNING: WITNESS option enabled, expect reduced performance.

lock order reversal:
  1st 0xfffff800430c0d50 ufs (ufs) @ /usr/src/sys/kern/vfs_mount.c:1224
  2nd 0xfffff800431cc418 devfs (devfs) @ 
/usr/src/sys/ufs/ffs/ffs_vfsops.c:1375
stack backtrace:
#0 0xffffffff80a7a2a0 at witness_debugger+0x70
#1 0xffffffff80a7a1a1 at witness_checkorder+0xe71
#2 0xffffffff809fb9bb at __lockmgr_args+0xd3b
#3 0xffffffff80ac276c at vop_stdlock+0x3c
#4 0xffffffff80fb81d0 at VOP_LOCK1_APV+0x100
#5 0xffffffff80ae366a at _vn_lock+0x9a
#6 0xffffffff80cb812a at ffs_flushfiles+0x11a
#7 0xffffffff80c9caef at softdep_flushfiles+0x3cf
#8 0xffffffff80cbab84 at ffs_unmount+0x84
#9 0xffffffff80acc200 at dounmount+0x530
#10 0xffffffff80acbc3d at sys_unmount+0x35d
#11 0xffffffff80e6b15b at amd64_syscall+0x2db
#12 0xffffffff80e4afdb at Xfast_syscall+0xfb