reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git/commit/?id=c2abb22c9f24b8570ba3fe1c115908b142514b99
        git remote add rppt https://git.kernel.org/pub/scm/linux/kernel/git/rppt/linux.git
        git fetch --no-tags rppt gfp-to-kmalloc/v0.1
        git checkout c2abb22c9f24b8570ba3fe1c115908b142514b99

        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # apt-get install llvm-dev

        # save the config file
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-14.2.0 ~/lkp-tests/kbuild/make.cross W=1 ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-14.2.0 ~/lkp-tests/kbuild/make.cross W=1 ARCH=s390 
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-14.2.0 ~/lkp-tests/kbuild/make.cross W=1 headers_install
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-14.2.0 ~/lkp-tests/kbuild/make.cross W=1 -C tools/testing/selftests