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
        git remote add trondmy-nfs git://git.linux-nfs.org/projects/trondmy/linux-nfs.git
        git fetch trondmy-nfs linux-next
        git checkout trondmy-nfs/linux-next
        b4 shazam https://lore.kernel.org/r/bbf929d6-18d2-4b7e-a660-a19460af0a3c@moroto.mountain
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=s390 SHELL=/bin/bash fs/nfsd/