reproduce (this is a W=1 build):
        git remote add anna-nfs git://git.linux-nfs.org/projects/anna/linux-nfs.git
        git fetch --no-tags anna-nfs linux-next
        git checkout 67ee714244dfb06cdeab07ee624e2eeddab35067
        # install powerpc cross compiling tool for clang build
        # apt-get install binutils-powerpc-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=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-19 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=powerpc SHELL=/bin/bash fs/nfs/flexfilelayout/