attach_mnt
attach_mnt(mnt, parent, mp);
attach_mnt(dst_mnt, dst_parent, src_parent->mnt_mp);
attach_mnt(mnt, new_ns_root, mp.mp);
attach_mnt(new_mnt, root_parent, root_mnt->mnt_mp);
attach_mnt(root_mnt, old_mnt, old_mp.mp);
attach_mnt(real_mount(mnt), mp.parent, mp.mp);