kernel fault when doing some I/O

[Aioanei Rares]

Hi everyone, 

I've been getting this several times but only now I could get a screenshot (it's a X-less VirtualBox host)
The message I'm getting is the following :

lock order reversal :
 1st 0xffffff800a4c8698 bufwait (bufwait) @ /usr/src/sys/kern/vfs_bio.c:2559
 2nd 0xffffff0002b81000 dirhash (dirhash) @ /usr/src/sys/ufs/ufs/ufs_dirhash.c:285
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
_witness_debugger() at _witness_debugger+0x2e
witness_checkorder() at witness_checkorder+0x81e
_sx_xlock() at _sx_lock+0x55
ufsdirhash_acquire() at ufsdirhash_acquire+0x33
ufsdirhash_add() at ufsdirhash_add+0x19
ufs_direnter() at ufs_direnter+0x889
ufs_makeinode() at ufs_makeinode+0x38a
VOP_CREATE_APV() at VOP_CREATE_APV+0x8d
vn_open_cred() at vn_open_cred+0x473
kern_openat() at kern_openat+0x179
syscall() at syscall+0x1ae
Xfast_syscall() at Xfast_syscall+0xe1
--- syscall (5, FreeBSD ELF64, open), rip = 0x800c1095c, rsp = 0x7fffff1f9b38, rbp = 0x800e0a900 ---

I was doing an update of my src tree, if that matters. Hope this helps. :)

-- 
Aioanei Rares <bsdlisten at gmail.com>