reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git/commit/?id=b3a8a00229ce2b0367afff075a00d53b92e1234a
        git remote add akpm-mm https://git.kernel.org/pub/scm/linux/kernel/git/akpm/mm.git
        git fetch --no-tags akpm-mm mm-new
        git checkout b3a8a00229ce2b0367afff075a00d53b92e1234a

        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=$HOME/0day COMPILER=gcc-10.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=csky olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-10.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=csky SHELL=/bin/bash