From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761116AbYBTJAr (ORCPT ); Wed, 20 Feb 2008 04:00:47 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755254AbYBTJAk (ORCPT ); Wed, 20 Feb 2008 04:00:40 -0500 Received: from relay2.sgi.com ([192.48.171.30]:42667 "EHLO relay.sgi.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1753546AbYBTJAj (ORCPT ); Wed, 20 Feb 2008 04:00:39 -0500 Date: Wed, 20 Feb 2008 03:00:36 -0600 From: Robin Holt To: Nick Piggin Cc: Robin Holt , Christoph Lameter , akpm@linux-foundation.org, Andrea Arcangeli , Avi Kivity , Izik Eidus , kvm-devel@lists.sourceforge.net, Peter Zijlstra , general@lists.openfabrics.org, Steve Wise , Roland Dreier , Kanoj Sarcar , steiner@sgi.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com Subject: Re: [patch 5/6] mmu_notifier: Support for drivers with revers maps (f.e. for XPmem) Message-ID: <20080220090035.GG11391@sgi.com> References: <20080215064859.384203497@sgi.com> <200802201055.21343.nickpiggin@yahoo.com.au> <20080220031221.GE11391@sgi.com> <200802201451.46069.nickpiggin@yahoo.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200802201451.46069.nickpiggin@yahoo.com.au> User-Agent: Mutt/1.5.15+20070412 (2007-04-11) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 20, 2008 at 02:51:45PM +1100, Nick Piggin wrote: > On Wednesday 20 February 2008 14:12, Robin Holt wrote: > > For XPMEM, we do not currently allow file backed > > mapping pages from being exported so we should never reach this condition. > > It has been an issue since day 1. We have operated with that assumption > > for 6 years and have not had issues with that assumption. The user of > > xpmem is MPT and it controls the communication buffers so it is reasonable > > to expect this type of behavior. > > OK, that makes things simpler. > > So why can't you export a device from your xpmem driver, which > can be mmap()ed to give out "anonymous" memory pages to be used > for these communication buffers? Because we need to have heap and stack available as well. MPT does not control all the communication buffer areas. I haven't checked, but this is the same problem that IB will have. I believe they are actually allowing any memory region be accessible, but I am not sure of that. Thanks, Robin From mboxrd@z Thu Jan 1 00:00:00 1970 From: Robin Holt Subject: [ofa-general] Re: [patch 5/6] mmu_notifier: Support for drivers with revers maps (f.e. for XPmem) Date: Wed, 20 Feb 2008 03:00:36 -0600 Message-ID: <20080220090035.GG11391@sgi.com> References: <20080215064859.384203497@sgi.com> <200802201055.21343.nickpiggin@yahoo.com.au> <20080220031221.GE11391@sgi.com> <200802201451.46069.nickpiggin@yahoo.com.au> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: steiner@sgi.com, Andrea Arcangeli , Peter Zijlstra , linux-mm@kvack.org, Izik Eidus , Kanoj Sarcar , Roland Dreier , linux-kernel@vger.kernel.org, Avi Kivity , kvm-devel@lists.sourceforge.net, daniel.blueman@quadrics.com, Robin Holt , general@lists.openfabrics.org, akpm@linux-foundation.org, Christoph Lameter To: Nick Piggin Return-path: Content-Disposition: inline In-Reply-To: <200802201451.46069.nickpiggin@yahoo.com.au> List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: general-bounces@lists.openfabrics.org Errors-To: general-bounces@lists.openfabrics.org List-Id: kvm.vger.kernel.org On Wed, Feb 20, 2008 at 02:51:45PM +1100, Nick Piggin wrote: > On Wednesday 20 February 2008 14:12, Robin Holt wrote: > > For XPMEM, we do not currently allow file backed > > mapping pages from being exported so we should never reach this condition. > > It has been an issue since day 1. We have operated with that assumption > > for 6 years and have not had issues with that assumption. The user of > > xpmem is MPT and it controls the communication buffers so it is reasonable > > to expect this type of behavior. > > OK, that makes things simpler. > > So why can't you export a device from your xpmem driver, which > can be mmap()ed to give out "anonymous" memory pages to be used > for these communication buffers? Because we need to have heap and stack available as well. MPT does not control all the communication buffer areas. I haven't checked, but this is the same problem that IB will have. I believe they are actually allowing any memory region be accessible, but I am not sure of that. Thanks, Robin From mboxrd@z Thu Jan 1 00:00:00 1970 Date: Wed, 20 Feb 2008 03:00:36 -0600 From: Robin Holt Subject: Re: [patch 5/6] mmu_notifier: Support for drivers with revers maps (f.e. for XPmem) Message-ID: <20080220090035.GG11391@sgi.com> References: <20080215064859.384203497@sgi.com> <200802201055.21343.nickpiggin@yahoo.com.au> <20080220031221.GE11391@sgi.com> <200802201451.46069.nickpiggin@yahoo.com.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200802201451.46069.nickpiggin@yahoo.com.au> Sender: owner-linux-mm@kvack.org Return-Path: To: Nick Piggin Cc: Robin Holt , Christoph Lameter , akpm@linux-foundation.org, Andrea Arcangeli , Avi Kivity , Izik Eidus , kvm-devel@lists.sourceforge.net, Peter Zijlstra , general@lists.openfabrics.org, Steve Wise , Roland Dreier , Kanoj Sarcar , steiner@sgi.com, linux-kernel@vger.kernel.org, linux-mm@kvack.org, daniel.blueman@quadrics.com List-ID: On Wed, Feb 20, 2008 at 02:51:45PM +1100, Nick Piggin wrote: > On Wednesday 20 February 2008 14:12, Robin Holt wrote: > > For XPMEM, we do not currently allow file backed > > mapping pages from being exported so we should never reach this condition. > > It has been an issue since day 1. We have operated with that assumption > > for 6 years and have not had issues with that assumption. The user of > > xpmem is MPT and it controls the communication buffers so it is reasonable > > to expect this type of behavior. > > OK, that makes things simpler. > > So why can't you export a device from your xpmem driver, which > can be mmap()ed to give out "anonymous" memory pages to be used > for these communication buffers? Because we need to have heap and stack available as well. MPT does not control all the communication buffer areas. I haven't checked, but this is the same problem that IB will have. I believe they are actually allowing any memory region be accessible, but I am not sure of that. Thanks, Robin -- 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