From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758561Ab2CGODI (ORCPT ); Wed, 7 Mar 2012 09:03:08 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:33939 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756539Ab2CGODG (ORCPT ); Wed, 7 Mar 2012 09:03:06 -0500 Date: Wed, 7 Mar 2012 15:02:46 +0100 From: Ingo Molnar To: "Srivatsa S. Bhat" Cc: Konstantin Khlebnikov , Peter Zijlstra , linux-kernel@vger.kernel.org, Andrew Morton , Linus Torvalds , prashanth@linux.vnet.ibm.com, "Rafael J. Wysocki" , Linux PM mailing list , Srivatsa Vaddagiri , "paulmck@linux.vnet.ibm.com >> \"Paul E. McKenney\"" Subject: Re: [PATCH bisected regression] sched: rebuild sched domains at suspend/resume Message-ID: <20120307140246.GC12676@elte.hu> References: <20120306204357.13169.90791.stgit@zurg> <4F5763CD.8050903@linux.vnet.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4F5763CD.8050903@linux.vnet.ibm.com> User-Agent: Mutt/1.5.21 (2010-09-15) 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=AWL,BAYES_00 autolearn=no SpamAssassin version=3.3.1 -2.0 BAYES_00 BODY: Bayes spam probability is 0 to 1% [score: 0.0000] 0.0 AWL AWL: From: address is in the auto white-list Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Srivatsa S. Bhat wrote: > On 03/07/2012 02:15 AM, Konstantin Khlebnikov wrote: > > > This is fix for suspend/resume regression introduced in > > commit 8f2f748b0656 ("CPU hotplug, cpusets, suspend: Don't > > touch cpusets during suspend/resume") Without this patch > > suspend always hangs on my thinkpad x220 (2 x CPU * HT). > > > Hey, with commit 8f2f748b0656, suspend/resume works perfectly > for me! I ran it multiple times just to make sure, and > everything worked just great. > > Apart from that, I even tried suspend/resume after building > the kernel with and without CONFIG_CPUSETS. Both cases worked > perfectly. > > So, I am really surprised at what you stated above. Are you > *really* sure you are facing suspend hangs *because* of the > above commit? That's not the only information Konstantin gave: he also provided a patch, which activates a side-effect that got removed by your patch - and voila, s2ram was working for him again. At this point I don't think we should doubt the messenger, we should doubt our assumptions and we should go for a clean revert ASAP. I don't see the underlying bug straight away, but clearly my assumptions of this patch not causing problems, when I applied the patch, are not valid anymore. So if Linus wants to revert the commit straight away: Acked-by: Ingo Molnar > And AFAICS hardware doesn't matter for the code in question, but in any case, > the laptop on which I tested it is: > Thinkpad T420 (Intel core i5-2540M), 2 cores * HT (total 4 logical cpus). Well, any environmental detail might matter as long as we don't understand the bug. > Also, the patch you posted here doesn't make much sense.. nor > does it give a clue as to what might be wrong at your end (if > anything is really wrong, that is). Do you have CONFIG_CPUSETS > set or unset? Could you share your .config? His patch is simply the re-creation of a side-effect that the kernel had before - and it made suspend work for him. While it is not a patch we want to apply, it sure was a valid and valuable experiment to perform. Thanks, Ingo