reproduce (this is a W=1 build):
        # https://github.com/norov/linux/commit/04ae3062fb41ac0c5445a26ddc6c1b0ca2562e8e
        git remote add norov https://github.com/norov/linux
        git fetch --no-tags norov cpumask_next
        git checkout 04ae3062fb41ac0c5445a26ddc6c1b0ca2562e8e
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=um olddefconfig
        make W=1 O=build_dir ARCH=um SHELL=/bin/bash drivers/net/