From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from psmtp.com (na3sys010amx123.postini.com [74.125.245.123]) by kanga.kvack.org (Postfix) with SMTP id 6E2C86B0085 for ; Wed, 5 Jun 2013 19:29:39 -0400 (EDT) Date: Wed, 5 Jun 2013 20:29:33 -0300 From: Rafael Aquini Subject: Re: [PATCH] virtio_balloon: leak_balloon(): only tell host if we got pages deflated Message-ID: <20130605232932.GA30387@optiplex.redhat.com> References: <20130605171031.7448deea@redhat.com> <20130605212449.GB19617@optiplex.redhat.com> <20130605190844.1e96bbde@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20130605190844.1e96bbde@redhat.com> Sender: owner-linux-mm@kvack.org List-ID: To: Luiz Capitulino Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kvm@vger.kernel.org On Wed, Jun 05, 2013 at 07:08:44PM -0400, Luiz Capitulino wrote: > On Wed, 5 Jun 2013 18:24:49 -0300 > Rafael Aquini wrote: > > > On Wed, Jun 05, 2013 at 05:10:31PM -0400, Luiz Capitulino wrote: > > > The balloon_page_dequeue() function can return NULL. If it does for > > > the first page being freed, then leak_balloon() will create a > > > scatter list with len=0. Which in turn seems to generate an invalid > > > virtio request. > > > > > > Signed-off-by: Luiz Capitulino > > > --- > > > > > > PS: I didn't get this in practice. I found it by code review. On the other > > > hand, automatic-ballooning was able to put such invalid requests in > > > the virtqueue and QEMU would explode... > > > > > > > Nice catch! The patch looks sane and replicates the check done at > > fill_balloon(). I think we also could use this P.S. as a commentary > > to let others aware of this scenario. Thanks Luiz! > > Want me to respin? > That would be great, indeed. I guess the commentary could also go for the same if case at fill_balloon(), assuming the tests are placed to prevent the same scenario you described at changelog. You can stick my Ack on it, if reposting. Cheers! -- Rafael -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org