reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://github.com/paulmckrcu/linux/commit/2ad3ef4260e9bd8628025b35fa2613c7e4e7720f
        git remote add paulmckrcu https://github.com/paulmckrcu/linux
        git fetch --no-tags paulmckrcu dev
        git checkout 2ad3ef4260e9bd8628025b35fa2613c7e4e7720f
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arc olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-8.5.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arc SHELL=/bin/bash kernel/