reproduce (this is a W=1 build):
        # https://github.com/paulmckrcu/linux/commit/f7cd407d56a0baf6fc9fe3e093253f6e30d61a95
        git remote add paulmckrcu https://github.com/paulmckrcu/linux
        git fetch --no-tags paulmckrcu next.2025.10.30c
        git checkout f7cd407d56a0baf6fc9fe3e093253f6e30d61a95

        # install s390 cross compiling tool for clang build
        # apt-get install binutils-s390x-linux-gnu
        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=$HOME/0day COMPILER=clang-16 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-16 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash kernel/rcu/