reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-66-g0196afe1
        # https://github.com/kkdwivedi/linux/commit/78b8828eae603e326faa2784533ab560ff3979ce
        git remote add kkdwivedi https://github.com/kkdwivedi/linux
        git fetch --no-tags kkdwivedi res-lock-v4
        git checkout 78b8828eae603e326faa2784533ab560ff3979ce
        # 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=i386 olddefconfig
        make W=1 C=1 CF='-fdiagnostic-prefix -D__CHECK_ENDIAN__ -fmax-errors=unlimited -fmax-warnings=unlimited' O=build_dir ARCH=i386 SHELL=/bin/bash kernel/bpf/ kernel/locking/