reproduce (this is a W=1 build):
        # https://github.com/sean-jc/linux/commit/7df9be2ef92ca4407a365455e0670f4f07af7e25
        git remote add sean-jc https://github.com/sean-jc/linux
        git fetch --no-tags sean-jc x86/stale_mmio_cleanup
        git checkout 7df9be2ef92ca4407a365455e0670f4f07af7e25
        # save the config file
        mkdir build_dir && cp config build_dir/.config
        make W=1 O=build_dir ARCH=i386 olddefconfig
        make W=1 O=build_dir ARCH=i386 SHELL=/bin/bash arch/x86/kvm/