From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755113AbbFQLwG (ORCPT ); Wed, 17 Jun 2015 07:52:06 -0400 Received: from mx1.redhat.com ([209.132.183.28]:55845 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752219AbbFQLv7 (ORCPT ); Wed, 17 Jun 2015 07:51:59 -0400 Date: Wed, 17 Jun 2015 13:51:56 +0200 From: "Michael S. Tsirkin" To: Igor Mammedov Cc: linux-kernel@vger.kernel.org, kvm@vger.kernel.org, pbonzini@redhat.com Subject: Re: [PATCH 3/5] vhost: support upto 509 memory regions Message-ID: <20150617134848-mutt-send-email-mst@redhat.com> References: <20150616231201-mutt-send-email-mst@redhat.com> <20150617000056.481e4a96@igors-macbook-pro.local> <20150617083202-mutt-send-email-mst@redhat.com> <20150617092802.5c8d8475@igors-macbook-pro.local> <20150617092910-mutt-send-email-mst@redhat.com> <20150617105421.71751f44@nial.brq.redhat.com> <20150617110711-mutt-send-email-mst@redhat.com> <20150617123742.5c3fec30@nial.brq.redhat.com> <20150617123842-mutt-send-email-mst@redhat.com> <20150617134803.5a03d04e@nial.brq.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20150617134803.5a03d04e@nial.brq.redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 17, 2015 at 01:48:03PM +0200, Igor Mammedov wrote: > > > So far it's kernel limitation and this patch fixes crashes > > > that users see now, with the rest of patches enabling performance > > > not to regress. > > > > When I say regression I refer to an option to limit the array > > size again after userspace started using the larger size. > Is there a need to do so? Considering userspace can be malicious, I guess yes. > Userspace that cares about memory footprint won't use many slots > keeping it low and user space that can't do without many slots > or doesn't care will have bigger memory footprint. We really can't trust userspace to do the right thing though. -- MST