From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dave Hansen Subject: Re: [PATCH v11 4/6] mm: function to offer a page block on the free list Date: Mon, 12 Jun 2017 09:42:36 -0700 Message-ID: <9d0900f3-9df5-ac63-4069-2d796f2a5bc7__29179.063338279$1497285763$gmane$org@intel.com> References: <1497004901-30593-1-git-send-email-wei.w.wang@intel.com> <1497004901-30593-5-git-send-email-wei.w.wang@intel.com> <20170612181354-mutt-send-email-mst@kernel.org> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20170612181354-mutt-send-email-mst@kernel.org> Content-Language: en-US List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: virtualization-bounces@lists.linux-foundation.org Errors-To: virtualization-bounces@lists.linux-foundation.org To: "Michael S. Tsirkin" Cc: aarcange@redhat.com, kvm@vger.kernel.org, qemu-devel@nongnu.org, amit.shah@redhat.com, liliang.opensource@gmail.com, linux-kernel@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-mm@kvack.org, cornelia.huck@de.ibm.com, pbonzini@redhat.com, akpm@linux-foundation.org, mgorman@techsingularity.net List-Id: virtualization@lists.linuxfoundation.org On 06/12/2017 09:28 AM, Michael S. Tsirkin wrote: > >> The hypervisor is going to throw away the contents of these pages, >> right? > It should be careful and only throw away contents that was there before > report_unused_page_block was invoked. Hypervisor is responsible for not > corrupting guest memory. But that's not something an mm patch should > worry about. That makes sense. I'm struggling to imagine how the hypervisor makes use of this information, though. Does it make the pages read-only before this, and then it knows if there has not been a write *and* it gets notified via this new mechanism that it can throw the page away?