reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git/commit/?id=40ced64186624690248a72f77202a245eb1717e3
        git remote add rppt https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git
        git fetch --no-tags rppt uffd+guestmemfd/v1
        git checkout 40ced64186624690248a72f77202a245eb1717e3

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests

        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=nios2 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-11.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=nios2 SHELL=/bin/bash mm/