From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S263589AbUD2GfA (ORCPT ); Thu, 29 Apr 2004 02:35:00 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S263605AbUD2GfA (ORCPT ); Thu, 29 Apr 2004 02:35:00 -0400 Received: from holomorphy.com ([207.189.100.168]:130 "EHLO holomorphy.com") by vger.kernel.org with ESMTP id S263589AbUD2Gd2 (ORCPT ); Thu, 29 Apr 2004 02:33:28 -0400 Date: Wed, 28 Apr 2004 23:32:56 -0700 From: William Lee Irwin III To: Hugh Dickins Cc: Rik van Riel , Andrew Morton , Rajesh Venkatasubramanian , Russell King , James Bottomley , linux-kernel@vger.kernel.org Subject: Re: [PATCH] rmap 18 i_mmap_nonlinear Message-ID: <20040429063256.GH737@holomorphy.com> Mail-Followup-To: William Lee Irwin III , Hugh Dickins , Rik van Riel , Andrew Morton , Rajesh Venkatasubramanian , Russell King , James Bottomley , linux-kernel@vger.kernel.org References: <20040428234448.GB737@holomorphy.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.5.1+cvs20040105i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 28 Apr 2004, William Lee Irwin III wrote: >> I believe the flush_dcache_page() implementations touching >> ->i_mmap_shared care about this distinction. On Thu, Apr 29, 2004 at 07:10:59AM +0100, Hugh Dickins wrote: > That's right, arm and parisc do handle them differently: currently > arm ignores i_mmap (and I think rmk was wondering a few months ago > whether that's actually correct, given that MAP_SHARED mappings > which can never become writable go in there - and that surprise is > itself a very good reason for combining them), and parisc... ah, > what it does in Linus' tree at present is about the same for both, > but there are some changes on the way. > The differences are not going to be enough to deserve two separate > prio_tree_roots in every struct address_space, we can check vm_flags > for any differences if necessary. It seemed these two actually wanted a precise recovery of virtual addresses and the like for flush_dcache_page() like they would have had with pte_chains, but never got around to using it. On Thu, Apr 29, 2004 at 07:10:59AM +0100, Hugh Dickins wrote: > Something else I should have commented on, in that patch comment or > the next: although we now have the separate i_mmap_nonlinear list, > no attempt to search it for nonlinear pages in flush_dcache_page. > It looks like parisc has no sys_remap_file_pages syscall anyway, > and arm only flushes current active_mm, so should be okay so long > as people don't mix linear and nonlinear maps of same pages (hmm, > and don't map same page twice in a nonlinear: more likely) in same > mm: anyway, I think any problems there have to be a "Don't do that", > searching page tables in flush_dcache_page would be too too painful. Maybe it's worth #ifdef'ing out core remap_file_pages() support for those arches if all it can do is harm to them wrt. cache coherency issues. ARM probably wouldn't mind conserving the code it otherwise wouldn't use. -- wli