reproduce:
        # https://git.kernel.org/pub/scm/linux/kernel/git/sj/linux.git/commit/?id=43414b4cb39a85c66e164f34d962e88a143a439a
        git remote add sj https://git.kernel.org/pub/scm/linux/kernel/git/sj/linux.git
        git fetch --no-tags sj damon/next
        git checkout 43414b4cb39a85c66e164f34d962e88a143a439a
        make menuconfig
        # enable CONFIG_COMPILE_TEST, CONFIG_WARN_MISSING_DOCUMENTS, CONFIG_WARN_ABI_ERRORS
        # pip install -r Documentation/sphinx/requirements.txt
        make htmldocs