reproduce (this is a W=1 build):
        # https://git.kernel.org/pub/scm/linux/kernel/git/ljs/linux.git/commit/?id=1be9d553f4be97b754471cc04735f215e75c4bf2
        git remote add ljs https://git.kernel.org/pub/scm/linux/kernel/git/ljs/linux.git
        git fetch --no-tags ljs project/cow-context
        git checkout 1be9d553f4be97b754471cc04735f215e75c4bf2

        # install arm cross compiling tool for clang build
        # apt-get install binutils-arm-linux-gnueabi
        # clang-23 might not be officially released. Try a lower version if installation fails.
        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=$HOME/0day COMPILER=clang-23 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arm olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=clang-23 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=arm SHELL=/bin/bash kernel/ mm/