lor: zfs vs. syncer

[Andriy Gapon]

lock order reversal:
1st 0xffffff00753799d0 zfs (zfs) @ /usr/src/sys/kern/vfs_mount.c:1204
2nd 0xffffff005c62fd80 syncer (syncer) @ /usr/src/sys/kern/vfs_subr.c:2188
KDB: stack backtrace:
db_trace_self_wrapper() at 0xffffffff801b1b9a = db_trace_self_wrapper+0x2a
kdb_backtrace() at 0xffffffff80391542 = kdb_backtrace+0x32
_witness_debugger() at 0xffffffff803a561c = _witness_debugger+0x2c
witness_checkorder() at 0xffffffff803a6a89 = witness_checkorder+0x959
__lockmgr_args() at 0xffffffff80346cef = __lockmgr_args+0x7cf
vop_stdlock() at 0xffffffff803e2301 = vop_stdlock+0x51
VOP_LOCK1_APV() at 0xffffffff8057a0c0 = VOP_LOCK1_APV+0xf0
_vn_lock() at 0xffffffff803fe2a4 = _vn_lock+0x74
vrele() at 0xffffffff803f340b = vrele+0x13b
dounmount() at 0xffffffff803ea646 = dounmount+0x386
unmount() at 0xffffffff803eac20 = unmount+0x2d0
syscall() at 0xffffffff805233b9 = syscall+0x319
Xfast_syscall() at 0xffffffff80509181 = Xfast_syscall+0xe1

This seems to be of the same kind as:
http://sources.zabbadoz.net/freebsd/lor/236.html

-- 
Andriy Gapon