From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030472AbXCGIff (ORCPT ); Wed, 7 Mar 2007 03:35:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030481AbXCGIff (ORCPT ); Wed, 7 Mar 2007 03:35:35 -0500 Received: from smtp.osdl.org ([65.172.181.24]:56910 "EHLO smtp.osdl.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030472AbXCGIfe (ORCPT ); Wed, 7 Mar 2007 03:35:34 -0500 Date: Wed, 7 Mar 2007 00:35:20 -0800 From: Andrew Morton To: Ingo Molnar Cc: Nick Piggin , Linux Memory Management , Linux Kernel , Benjamin Herrenschmidt , "Paolo 'Blaisorblade' Giarrusso" Subject: Re: [patch 4/6] mm: merge populate and nopage into fault (fixes nonlinear) Message-Id: <20070307003520.08b1a082.akpm@linux-foundation.org> In-Reply-To: <20070307082755.GA25733@elte.hu> References: <20070221023656.6306.246.sendpatchset@linux.site> <20070221023735.6306.83373.sendpatchset@linux.site> <20070306225101.f393632c.akpm@linux-foundation.org> <20070307070853.GB15877@wotan.suse.de> <20070307081948.GA9563@wotan.suse.de> <20070307082755.GA25733@elte.hu> X-Mailer: Sylpheed version 2.2.7 (GTK+ 2.8.17; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 7 Mar 2007 09:27:55 +0100 Ingo Molnar wrote: > > * Nick Piggin wrote: > > > If it doesn't look very impressive, it could be because it leaves all > > the old crud around for backwards compatibility (the worst offenders > > are removed in patch 6/6). > > > > If you look at the patchset as a whole, it removes about 250 lines, > > mostly of (non trivial) duplicated code in filemap.c memory.c shmem.c > > fremap.c, that is nonlinear pages specific and doesn't get anywhere > > near the testing that the linear fault path does. > > > > A minimal fix for nonlinear pages would have required changing all > > ->populate handlers, which I simply thought was not very productive > > considering the testing and coverage issues, and that I was going to > > rewrite the nonlinear path anyway. > > > > If you like, you can consider patches 1,2,3 as the fix, and ignore > > nonlinear (hey, it doesn't even bother checking truncate_count > > today!). > > > > Then 4,5,6 is the fault/nonlinear rewrite, take it or leave it. I > > thought you would have liked the patches... > > btw., if we decide that nonlinear isnt worth the continuing maintainance > pain, we could internally implement/emulate sys_remap_file_pages() via a > call to mremap() and essentially deprecate it, without breaking the ABI > - and remove all the nonlinear code. (This would split fremap areas into > separate vmas) > I'm rather regretting having merged it - I don't think it has been used for much. Paolo's UML speedup patches might use nonlinear though.