reproduce (this is a W=1 build):
        # https://github.com/jimc/linux/commit/198cb0234063750d4125d2f5b3fd29f373fba200
        git remote add jimc https://github.com/jimc/linux.git
        git fetch --no-tags jimc folio-pool-v2-lockdep
        git checkout 198cb0234063750d4125d2f5b3fd29f373fba200
        # apt-get install sparse
        # sparse: v0.6.5-rc1

        # 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 kernel/locking/