reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux.git/commit/?id=b682759a2f8d90996861880b77d42606114647f2
        git remote add jlayton https://git.kernel.org/pub/scm/linux/kernel/git/jlayton/linux.git
        git fetch --no-tags jlayton uek-localio
        git checkout b682759a2f8d90996861880b77d42606114647f2
        # 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 net/rds/