reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # install s390 cross compiling tool for clang build
        # apt-get install binutils-s390x-linux-gnu
        # https://github.com/ceph/ceph-client/commit/6b738aa5f6bb2343f8277d318ff1e9ea9289212c
        git remote add ceph-client https://github.com/ceph/ceph-client.git
        git fetch --no-tags ceph-client tls-tracing-only
        git checkout 6b738aa5f6bb2343f8277d318ff1e9ea9289212c
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-18 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-18 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash fs/ceph/