reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/sj/linux.git/commit/?id=d9418cac100e220d93d44553fd8c9bc713dc2eb4
        git remote add sj https://git.kernel.org/pub/scm/linux/kernel/git/sj/linux.git
        git fetch --no-tags sj damon/next
        git checkout d9418cac100e220d93d44553fd8c9bc713dc2eb4
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash mm/damon/