From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756313AbdDMUoQ (ORCPT ); Thu, 13 Apr 2017 16:44:16 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:42165 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756202AbdDMUoO (ORCPT ); Thu, 13 Apr 2017 16:44:14 -0400 Date: Thu, 13 Apr 2017 13:44:11 -0700 From: Matthew Wilcox To: Wei Wang Cc: virtio-dev@lists.oasis-open.org, linux-kernel@vger.kernel.org, qemu-devel@nongnu.org, virtualization@lists.linux-foundation.org, kvm@vger.kernel.org, linux-mm@kvack.org, mst@redhat.com, david@redhat.com, dave.hansen@intel.com, cornelia.huck@de.ibm.com, akpm@linux-foundation.org, mgorman@techsingularity.net, aarcange@redhat.com, amit.shah@redhat.com, pbonzini@redhat.com, liliang.opensource@gmail.com Subject: Re: [PATCH v9 0/5] Extend virtio-balloon for fast (de)inflating & fast live migration Message-ID: <20170413204411.GJ784@bombadil.infradead.org> References: <1492076108-117229-1-git-send-email-wei.w.wang@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1492076108-117229-1-git-send-email-wei.w.wang@intel.com> User-Agent: Mutt/1.7.1 (2016-10-04) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Apr 13, 2017 at 05:35:03PM +0800, Wei Wang wrote: > 2) transfer the guest unused pages to the host so that they > can be skipped to migrate in live migration. I don't understand this second bit. You leave the pages on the free list, and tell the host they're free. What's preventing somebody else from allocating them and using them for something? Is the guest semi-frozen at this point with just enough of it running to ask the balloon driver to do things?