reproduce (this is a W=1 build):
        # https://github.com/sean-jc/linux/commit/e6c91f158091040c1e79a7dc9b8401235ae066b5
        git remote add sean-jc https://github.com/sean-jc/linux
        git fetch --no-tags sean-jc x86/dynamic_memslot_hashtable
        git checkout e6c91f158091040c1e79a7dc9b8401235ae066b5

        # 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 arch/x86/kvm/