reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/sashal/linux.git/commit/?id=30a926a5b094a325518d8faedaafebc50bf9ab84
        git remote add sashal https://git.kernel.org/pub/scm/linux/kernel/git/sashal/linux.git
        git fetch --no-tags sashal spec
        git checkout 30a926a5b094a325518d8faedaafebc50bf9ab84

        # 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 fs/ kernel/