accept$inet6(0xffffffffffffffff, 0x0, 0x0)
r0 = socket$inet6_udp(0xa, 0x2, 0x0)
setsockopt$inet6_IPV6_FLOWLABEL_MGR(r0, 0x29, 0x20, &(0x7f0000000880)={@mcast1, 0x0, 0x0, 0x0, 0x4}, 0x20)