reproduce (this is a W=1 build):
        # https://github.com/davidhildenbrand/linux/commit/0860b7bf763a2d4726b86810b14aae75e09c23fc
        git remote add davidhildenbrand https://github.com/davidhildenbrand/linux
        git fetch --no-tags davidhildenbrand virtio-mem-logically-offline
        git checkout 0860b7bf763a2d4726b86810b14aae75e09c23fc
        # 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 mm/