reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # https://github.com/gestionlin/linux/commit/49d60804ba15895c09e4b47eb20fdc8b56ed6878
        git remote add linyunsheng https://github.com/gestionlin/linux.git
        git fetch --no-tags linyunsheng page_frag_cache_v3
        git checkout 49d60804ba15895c09e4b47eb20fdc8b56ed6878
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=x86_64 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=x86_64 SHELL=/bin/bash net/sched/