From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030463AbXCGI2f (ORCPT ); Wed, 7 Mar 2007 03:28:35 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965144AbXCGI2e (ORCPT ); Wed, 7 Mar 2007 03:28:34 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:38963 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030463AbXCGI2e (ORCPT ); Wed, 7 Mar 2007 03:28:34 -0500 Date: Wed, 7 Mar 2007 09:27:55 +0100 From: Ingo Molnar To: Nick Piggin Cc: Andrew Morton , Linux Memory Management , Linux Kernel , Benjamin Herrenschmidt Subject: Re: [patch 4/6] mm: merge populate and nopage into fault (fixes nonlinear) Message-ID: <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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20070307081948.GA9563@wotan.suse.de> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.0.3 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org * 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) Ingo