reproduce (this is a W=1 build):
        git clone https://github.com/intel/lkp-tests.git ~/lkp-tests
        # https://github.com/gestionlin/linux/commit/6ae38e319d283fb5361b24f2d0e3b2501f1b9ade
        git remote add linyunsheng https://github.com/gestionlin/linux.git
        git fetch --no-tags linyunsheng page_frag_cache_prototype_v1
        git checkout 6ae38e319d283fb5361b24f2d0e3b2501f1b9ade
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-13.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=loongarch olddefconfig
        COMPILER_INSTALL_PATH=$HOME/0day COMPILER=gcc-13.2.0 ~/lkp-tests/kbuild/make.cross W=1 O=build_dir ARCH=loongarch SHELL=/bin/bash net/mptcp/