reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://github.com/zen-kernel/zen-kernel/commit/47715d438aa7c28ae732ab8cce27b832e93b6b51
        git remote add zen https://github.com/zen-kernel/zen-kernel
        git fetch --no-tags zen 6.7/zen-sauce
        git checkout 47715d438aa7c28ae732ab8cce27b832e93b6b51
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-13.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sh olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-13.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=sh SHELL=/bin/bash fs/bcachefs/