reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git/commit/?id=47f8fcd254f1a994c8ed16dcb7b6bf905c0af434
        git remote add linux-next https://git.kernel.org/pub/scm/linux/kernel/git/next/linux-next.git
        git fetch --no-tags linux-next master
        git checkout 47f8fcd254f1a994c8ed16dcb7b6bf905c0af434
        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