reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=af9199145b1977316b3c752e2124543e320f087f
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout af9199145b1977316b3c752e2124543e320f087f

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        make W=1 O=/tmp/kselftest headers
        make W=1 O=/tmp/kselftest
        make W=1 O=/tmp/kselftest -C tools/testing/selftests
        make W=1 O=/tmp/kselftest -C tools/testing/selftests/bpf