reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/snitzer/linux.git/commit/?id=1db309e3046ff4d7bc50071001f56700fec36d46
        git remote add snitzer https://git.kernel.org/pub/scm/linux/kernel/git/snitzer/linux.git
        git fetch --no-tags snitzer nfs-localio-for-6.11
        git checkout 1db309e3046ff4d7bc50071001f56700fec36d46
        # 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 fs/nfs/