reproduce:
        git checkout 39f54262ba499d862420a97719d2f0eea0cbd394
        b4 shazam https://lore.kernel.org/r/20250211-b4-ovpn-v19-25-86d5daf2a47a@openvpn.net
        make W=1 O=/tmp/kselftest headers
        make W=1 O=/tmp/kselftest -C tools/testing/selftests
        make W=1 O=/tmp/kselftest -C tools/testing/selftests/bpf