panic: mutex Giant not owned at /usr/src/sys/kern/vfs_subr.c:1943

(kgdb) where
#0  doadump () at pcpu.h:166
#1  0xc0582470 in boot (howto=260) at /usr/src/sys/kern/kern_shutdown.c:402
#2  0xc058271b in panic (fmt=0xc076000f "from debugger") at /usr/src/sys/kern/kern_shutdown.c:558
#3  0xc04756fd in db_panic (addr=-1067853541, have_addr=0, count=-1, modif=0xe2103984 "") at /usr/src/sys/ddb/db_command.c:426
#4  0xc0475694 in db_command (last_cmdp=0xc07f3d64, cmd_table=0x0) at /usr/src/sys/ddb/db_command.c:395
#5  0xc0475752 in db_command_loop () at /usr/src/sys/ddb/db_command.c:446
#6  0xc0477369 in db_trap (type=3, code=0) at /usr/src/sys/ddb/db_main.c:221
#7  0xc059db97 in kdb_trap (type=3, code=0, tf=0xe2103b0c) at /usr/src/sys/kern/subr_kdb.c:485
#8  0xc0722e80 in trap (frame=
       {tf_fs = -502267896, tf_es = -1067843544, tf_ds = -1065943000, tf_edi = 1, tf_esi = -1065899213, tf_ebp = -502252724, tf_isp = -502252744, tf_ebx = -502252680, tf_edx = 0, tf_ecx = -1056878592, tf_eax = 18, tf_trapno = 3, tf_err = 0, tf_eip = -1067853541, tf_cs = 32, tf_eflags = 642, tf_esp = -502252692, tf_ss = -1067964725}) at /usr/src/sys/i386/i386/trap.c:622
#9  0xc071160a in calltrap () at /usr/src/sys/i386/i386/exception.s:137
#10 0xc059d91b in kdb_enter (msg=0x12 <Address 0x12 out of bounds>) at cpufunc.h:60
#11 0xc05826cb in panic (fmt=0xc077ab33 "mutex %s not owned at %s:%d") at /usr/src/sys/kern/kern_shutdown.c:542
#12 0xc05798c2 in _mtx_assert (m=0xc07fe908, what=-1056878592, file=0xc07855e4 "/usr/src/sys/kern/vfs_subr.c", line=1943)
    at /usr/src/sys/kern/kern_mutex.c:755
#13 0xc05dd9a3 in vget (vp=0xc4db2b2c, flags=8194, td=0xc49f8cb0) at /usr/src/sys/kern/vfs_subr.c:1943
#14 0xc05d5c96 in vfs_hash_get (mp=0xc4a19400, hash=353286, flags=2, td=0xc49f8cb0, vpp=0xe2103c90, fn=0, arg=0x0)
    at /usr/src/sys/kern/vfs_hash.c:81
#15 0xc06b1b8b in ffs_vget (mp=0xc4a19400, ino=353286, flags=2, vpp=0xe2103c90) at pcpu.h:163
#16 0xc06aa331 in handle_workitem_remove (dirrem=0xc4a14c60, xp=0x12) at /usr/src/sys/ufs/ffs/ffs_softdep.c:3544
#17 0xc06a5d27 in process_worklist_item (mp=0xc4a19400, flags=0) at /usr/src/sys/ufs/ffs/ffs_softdep.c:947
#18 0xc06a5ad8 in softdep_process_worklist (mp=0xc4a19400, full=0) at /usr/src/sys/ufs/ffs/ffs_softdep.c:838
#19 0xc06a58a7 in softdep_flush () at /usr/src/sys/ufs/ffs/ffs_softdep.c:752
#20 0xc056bbf4 in fork_exit (callout=0xc06a57b8 <softdep_flush>, arg=0x0, frame=0xe2103d38)
    at /usr/src/sys/kern/kern_fork.c:802
#21 0xc071166c in fork_trampoline () at /usr/src/sys/i386/i386/exception.s:198
(kgdb) l *0xc05dd9a3
0xc05dd9a3 is in vget (/usr/src/sys/kern/vfs_subr.c:1943).
1938            int error;
1939
1940            error = 0;
1941            oldflags = flags;
1942            oweinact = 0;
1943            VFS_ASSERT_GIANT(vp->v_mount);
1944            if ((flags & LK_INTERLOCK) == 0)
1945                    VI_LOCK(vp);
1946            /*
1947             * If the inactive call was deferred because vput() was called

Core file available.

-- 
AIM-UANIC