reproduce (this is a W=1 build):
        # https://github.com/agraf/linux-2.6/commit/81ee2fbdd7aa2d3bdbef8e22556cef1e9bfb99c0
        git remote add agraf-2.6 https://github.com/agraf/linux-2.6.git
        git fetch --no-tags agraf-2.6 kvm-kho-gmem-test
        git checkout 81ee2fbdd7aa2d3bdbef8e22556cef1e9bfb99c0
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=x86_64 olddefconfig
        make W=1 O=build_dir ARCH=x86_64 SHELL=/bin/bash mm/