reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-52-g1cf3d98c-dirty
        # https://github.com/gmprice/linux/commit/8b894625fd0b7f702c0aa6e14bb673c59f42effc
        git remote add gmprice https://github.com/gmprice/linux
        git fetch --no-tags gmprice weighted_interleave-next
        git checkout 8b894625fd0b7f702c0aa6e14bb673c59f42effc
        # 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 mm/