LOR in zfs/syncer

[Robert Schulze]

Hi,

during zfs destroy, the following LOR appeared:

lock order reversal:
  1st 0xffffff007c26fa58 zfs (zfs) @ /usr/src/sys/kern/vfs_mount.c:1204
  2nd 0xffffff0126175a58 syncer (syncer) @ /usr/src/sys/kern/vfs_subr.c:2232
KDB: stack backtrace:
db_trace_self_wrapper() at db_trace_self_wrapper+0x2a
kdb_backtrace() at kdb_backtrace+0x37
_witness_debugger() at _witness_debugger+0x49
witness_checkorder() at witness_checkorder+0x7d3
__lockmgr_args() at __lockmgr_args+0xd0b
vop_stdlock() at vop_stdlock+0x39
VOP_LOCK1_APV() at VOP_LOCK1_APV+0x9b
_vn_lock() at _vn_lock+0x5d
vputx() at vputx+0x2f5
dounmount() at dounmount+0x26d
unmount() at unmount+0x27f
syscallenter() at syscallenter+0xe5
syscall() at syscall+0x55
Xfast_syscall() at Xfast_syscall+0xe2
--- syscall (22, FreeBSD ELF64, unmount), rip = 0x800f444dc, rsp = 
0x7fffffffe1e8, rbp = 0x801204300 ---

uname -a:

FreeBSD xxxxx 8.2-RC3 FreeBSD 8.2-RC3 #3: Mon Jan 31 12:57:26 CET 2011 
    root at xxxxx:/usr/obj/usr/src/sys/BAK  amd64


with kind regards,

Robert Schulze