From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759758AbYAUQlU (ORCPT ); Mon, 21 Jan 2008 11:41:20 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752957AbYAUQlL (ORCPT ); Mon, 21 Jan 2008 11:41:11 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:37737 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752805AbYAUQlJ (ORCPT ); Mon, 21 Jan 2008 11:41:09 -0500 Date: Mon, 21 Jan 2008 17:40:52 +0100 From: Ingo Molnar To: Andi Kleen Cc: linux-kernel@vger.kernel.org, tglx@linutronix.de, jbeulich@novell.com, venkatesh.pallipadi@intel.com, "H. Peter Anvin" Subject: Re: CPA boot crash (was: [PATCH] [0/36] Great change_page_attr patch series v3) Message-ID: <20080121164052.GA11364@elte.hu> References: <200801161114.239449000@suse.de> <200801181734.51193.ak@suse.de> <20080118164853.GA17589@elte.hu> <200801181819.58675.ak@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200801181819.58675.ak@suse.de> User-Agent: Mutt/1.5.17 (2007-11-01) X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.3 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Andi Kleen wrote: > > i pointed it out how to port a larger series ontop of a whitespace > > cleanup patch: > > > > http://lkml.org/lkml/2008/1/18/281 > > > > the "there's an easy technique" bit. > > But it will be even easier to just redo the cleanup stuff at the end. > If I do what you describe here I'm sure I will make a mistake > somewhere and I would rather not risk that. FYI, i've done the proper splitup of your CPA patchset - see today's x86.git#mm for the details. I've extracted all the c_p_a() fixes from your series and eliminated the 'undo cleanups' patch as well. It's a first shot so it might not yet be perfect - although so far it looks good in testing on 4-5 testsystems here, on mixed 64-bit and 32-bit boxes. Doing it this way was a pretty straightforward process, it took less than an hour - and the end result feels much better in terms of maintainability. I left the clflush feature bits out for now - fixes and cleanups go first. We first need to see whether this is robust enough before making other changes to c_p_a(). There's enough on the arch/x86 plate for v2.6.25 already - we can try the clflush optimizations in v2.6.26. (since there's no high-freq in-kernel user of the c_p_a() API at the moment, there's no pressing need for this either.) Anyway, could you check today's x86.git and see whether any of those fixes have some implicit dependency on other changes i left out of this splitup? That's the main high-level risk i can see for now. (besides the large number of changes to this fragile API) Also, CPA_DEBUG still produces warnings all around the place - as it did with your series. Ingo