lock order reversals on 10.0-ALPHA4

With:
FreeBSD lapr.js.berklix.net 10.0-ALPHA4 FreeBSD 10.0-ALPHA4 #0
r255933: Sun Sep 29 02:50:54 UTC 2013
root_at_snap.freebsd.org:/usr/obj/usr/src/sys/GENERIC  amd64

At boot dmesg shows several lock order reversals, eg

------
Trying to mount root from ufs:/dev/ad4s2a [rw]...
ipfw2 (+ipv6) initialized, divert loadable, nat loadable, default to deny, logging disabled
lock order reversal:
 1st 0xfffffe00a6e26b48 bufwait (bufwait) _at_ /usr/src/sys/kern/vfs_bio.c:3059
 2nd 0xfffff80005cf8400 dirhash (dirhash) _at_ /usr/src/sys/ufs/ufs/ufs_dirhash.c:284
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe00c8f3d3f0
kdb_backtrace() at kdb_backtrace+0x39/frame 0xfffffe00c8f3d4a0
witness_checkorder() at witness_checkorder+0xd23/frame 0xfffffe00c8f3d530
_sx_xlock() at _sx_xlock+0x75/frame 0xfffffe00c8f3d570
ufsdirhash_add() at ufsdirhash_add+0x3b/frame 0xfffffe00c8f3d5b0
ufs_direnter() at ufs_direnter+0x688/frame 0xfffffe00c8f3d670
ufs_makeinode() at ufs_makeinode+0x573/frame 0xfffffe00c8f3d830
ufs_symlink() at ufs_symlink+0x32/frame 0xfffffe00c8f3d880
VOP_SYMLINK_APV() at VOP_SYMLINK_APV+0xf0/frame 0xfffffe00c8f3d8b0
kern_symlinkat() at kern_symlinkat+0x23e/frame 0xfffffe00c8f3dae0
amd64_syscall() at amd64_syscall+0x265/frame 0xfffffe00c8f3dbf0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe00c8f3dbf0
--- syscall (57, FreeBSD ELF64, sys_symlink), rip = 0x800888ffa, rsp = 0x7fffffffca58, rbp = 0x7fffffffdc10 ---
lock order reversal:
 1st 0xfffff800881b9d50 ufs (ufs) _at_ /usr/src/sys/kern/vfs_mount.c:851
 2nd 0xfffff800881b99a0 devfs (devfs) _at_ /usr/src/sys/kern/vfs_subr.c:2099
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2b/frame 0xfffffe00c8ed93d0
kdb_backtrace() at kdb_backtrace+0x39/frame 0xfffffe00c8ed9480
witness_checkorder() at witness_checkorder+0xd23/frame 0xfffffe00c8ed9510
__lockmgr_args() at __lockmgr_args+0x6f2/frame 0xfffffe00c8ed9640
vop_stdlock() at vop_stdlock+0x3c/frame 0xfffffe00c8ed9660
VOP_LOCK1_APV() at VOP_LOCK1_APV+0xf5/frame 0xfffffe00c8ed9690
_vn_lock() at _vn_lock+0xab/frame 0xfffffe00c8ed9700
vget() at vget+0x70/frame 0xfffffe00c8ed9750
devfs_allocv() at devfs_allocv+0xfd/frame 0xfffffe00c8ed97a0
devfs_root() at devfs_root+0x43/frame 0xfffffe00c8ed97d0
vfs_donmount() at vfs_donmount+0x115e/frame 0xfffffe00c8ed9aa0
sys_nmount() at sys_nmount+0x72/frame 0xfffffe00c8ed9ae0
amd64_syscall() at amd64_syscall+0x265/frame 0xfffffe00c8ed9bf0
Xfast_syscall() at Xfast_syscall+0xfb/frame 0xfffffe00c8ed9bf0
--- syscall (378, FreeBSD ELF64, sys_nmount), rip = 0x800a9dd7a, rsp = 0x7fffffffccb8, rbp = 0x7fffffffd220 ---
----

It comes up multi user OK,
Do you already have enough lock order reversal to work on,
or do you want me to run diagnostics ? what ?

Cheers,
Julian
-- 
Julian Stacey, BSD Unix Linux C Sys Eng Consultant, Munich http://berklix.com
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