reproduce:
        # apt-get install sparse
        # sparse version: v0.6.4-46-gadceff0a-dirty
        # https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/?id=bbf854dc3570eb0a2b9d851f21e363e1570c717e
        git remote add linus https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
        git fetch --no-tags linus master
        git checkout bbf854dc3570eb0a2b9d851f21e363e1570c717e
        # 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 arch/x86/events/ arch/x86/kernel/ arch/x86/lib/ drivers/ fs/ init/ kernel/ lib/ mm/kasan/ net/9p/ net/core/ net/ipv4/ net/sunrpc/ security/ sound/soc/