UVM_VNODE_VNISLOCKED
vnlocked = (uvn->u_flags & UVM_VNODE_VNISLOCKED);
uvn->u_flags |= UVM_VNODE_DYING|UVM_VNODE_VNISLOCKED;
uvn->u_flags &= ~(UVM_VNODE_DYING|UVM_VNODE_VNISLOCKED|