reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git/commit/?id=a5d37500c54a90dc76e3e3e1cd3b0194b06d5461
        git remote add peterz-queue https://git.kernel.org/pub/scm/linux/kernel/git/peterz/queue.git
        git fetch --no-tags peterz-queue sched/flat
        git checkout a5d37500c54a90dc76e3e3e1cd3b0194b06d5461

        # 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 kernel/sched/