From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756398AbYKQCag (ORCPT ); Sun, 16 Nov 2008 21:30:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754711AbYKQCa1 (ORCPT ); Sun, 16 Nov 2008 21:30:27 -0500 Received: from cantor.suse.de ([195.135.220.2]:40875 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754723AbYKQCa0 (ORCPT ); Sun, 16 Nov 2008 21:30:26 -0500 Date: Mon, 17 Nov 2008 03:30:19 +0100 From: Nick Piggin To: "Pallipadi, Venkatesh" Cc: Ingo Molnar , Thomas Gleixner , H Peter Anvin , Hugh Dickins , Roland Dreier , Jesse Barnes , Jeremy Fitzhardinge , Arjan van de Ven , "linux-kernel@vger.kernel.org" , "Siddha, Suresh B" Subject: Re: [patch 2/8] x86 PAT: set VM_PFNMAP flag in vm_insert_pfn Message-ID: <20081117023019.GB1943@wotan.suse.de> References: <20081112212647.259698000@intel.com> <20081112212900.151113000@intel.com> <20081112232312.GB29363@wotan.suse.de> <7E82351C108FA840AB1866AC776AEC46426F30E5@orsmsx505.amr.corp.intel.com> <20081113034425.GA23434@wotan.suse.de> <7E82351C108FA840AB1866AC776AEC4642775AF2@orsmsx505.amr.corp.intel.com> <20081114020547.GA24414@wotan.suse.de> <7E82351C108FA840AB1866AC776AEC46427EC16C@orsmsx505.amr.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <7E82351C108FA840AB1866AC776AEC46427EC16C@orsmsx505.amr.corp.intel.com> User-Agent: Mutt/1.5.9i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, Nov 14, 2008 at 01:35:38PM -0800, Pallipadi, Venkatesh wrote: > > > >-----Original Message----- > >From: Nick Piggin [mailto:npiggin@suse.de] > >Sent: Thursday, November 13, 2008 6:06 PM > >To: Pallipadi, Venkatesh > >Cc: Ingo Molnar; Thomas Gleixner; H Peter Anvin; Hugh Dickins; > >Roland Dreier; Jesse Barnes; Jeremy Fitzhardinge; Arjan van de > >Ven; linux-kernel@vger.kernel.org; Siddha, Suresh B > >Subject: Re: [patch 2/8] x86 PAT: set VM_PFNMAP flag in vm_insert_pfn > > > >On Thu, Nov 13, 2008 at 10:47:23AM -0800, Pallipadi, Venkatesh wrote: > >> > >> Yes. It does. But, it calls a lower level insert_pfn() > >function. The lower > >> level insert_pfn() does not have any bug checks. But the higher level > >> vm_insert_pfn() checks for PFNMAP or MIXEDMAP. > > > >Yes, but is there anything extra you need to check for cache aliases in > >MIXEDMAP mappings? > > > > Yes. We need additional things to track MIXEDMAP and we are looking at that. > But, that is slightly more trickier than the general PFNMAP case. And > only in-tree user of MIXEDMAP is xip and that too it only uses it for > regular WB mapping. So, we thought we should fix the more common case > first here. > > With MIXEDMAP there is no way whether to distinguish whether insert_pfn > Or insert_page was used while looking at VMA. We can probably use PFNMAP > in addition to MIXEDMAP to indicate that, which will make things easier. It's difficult because it can have either method for a single VMA, and a given address in the vma may even change over time (not with current code in kernel AFAIKS, but AXFS eventually might get to that point). > But, we are still looking at that and trying to understand the change > implication. OK: now I understand correctly. Getting PFNMAP working is an important first step. I agree. Thanks, Nick