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