reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git/commit/?id=3cf00e4048276f677baca769649aea6fb5ae0f30
        git remote add mhiramat https://git.kernel.org/pub/scm/linux/kernel/git/mhiramat/linux.git
        git fetch --no-tags mhiramat topic/wprobe-v2
        git checkout 3cf00e4048276f677baca769649aea6fb5ae0f30
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # pip install -r Documentation/sphinx/requirements.txt
        make htmldocs