FreeBSD lock order reversal (LOR) #264

lock order reversal:
 1st 0xc3578044 user map (user map) @ sys/vm/vm_map.c:3115
 2nd 0xc373a6a0 zfs (zfs) @ sys/kern/vfs_subr.c:2049
		
KDB: stack backtrace:
db_trace_self_wrapper(c0bc5e25,c327691c,c0838f75,4,c0bc17b5,...) at db_trace_self_wrapper+0x26
kdb_backtrace(4,c0bc17b5,c0bcf4f9,c3523660,c3276974,...) at kdb_backtrace+0x29
_witness_debugger(c0bc86da,c373a6a0,c109790d,c3523660,c0bcf4f9,...) at _witness_debugger+0x25
witness_checkorder(c373a6a0,1,c0bcf4f9,801,0,...) at witness_checkorder+0x800
__lockmgr_args(c373a6a0,200501,c373a6bc,0,0,...) at __lockmgr_args+0x237
vop_stdlock(c3276a78,c0bea9cd,c0bbc3d4,200501,c373a648,...) at vop_stdlock+0x62
VOP_LOCK1_APV(c109bd20,c3276a78,c0cdd0c0,c373a648,200501,...) at VOP_LOCK1_APV+0xa5
_vn_lock(c373a648,200501,c0bcf4f9,801,4,...) at _vn_lock+0x5e
vget(c373a648,200501,c3574d20,4b4,0,...) at vget+0xc9
vnode_pager_lock(c1866c98,0,c0be7f93,127,c3276c18,...) at vnode_pager_lock+0x1e0
vm_fault(c3578000,80db000,2,8,80db020,...) at vm_fault+0x1df
trap_pfault(5,0,c0bf7580,2f5,c3572d0c,...) at trap_pfault+0x118
trap(c3276d38) at trap+0x289
calltrap() at calltrap+0x6
--- trap 0xc, eip = 0x80480e5, esp = 0xbfbfeef0, ebp = 0xbfbfef10 ---
		

• PR kern/128633
• Similar to LOR #235