From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Rafael J. Wysocki" Subject: Re: [Bug #12155] Regression in 2.6.28-rc and 2.6.27-stable - hibernate related Date: Sat, 13 Dec 2008 19:56:02 +0100 Message-ID: <200812131956.03495.rjw@sisk.pl> References: Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Content-Disposition: inline Sender: kernel-testers-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-ID: Content-Type: text/plain; charset="us-ascii" To: Fabio Comolli Cc: Linux Kernel Mailing List , Kernel Testers List , Dave Kleikamp , Peter Zijlstra , Ingo Molnar , Greg Kroah-Hartman , Chuck Ebbert , Linus Torvalds On Saturday, 13 of December 2008, Fabio Comolli wrote: > Hi. Hi, > On Sat, Dec 13, 2008 at 5:33 PM, Rafael J. Wysocki wrote: > > This message has been generated automatically as a part of a report > > of recent regressions. > > > > The following bug entry is on the current list of known regressions > > from 2.6.27. Please verify if it still should be listed and let me know > > (either way). > > > > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=12155 > > Subject : Regression in 2.6.28-rc and 2.6.27-stable - hibernate related > > Submitter : Fabio Comolli > > Date : 2008-11-23 16:17 (21 days old) > > References : http://marc.info/?l=linux-kernel&m=122745709926361&w=4 > > Still present. It has been bisected to: > > --------------------------------------------------------------------------------------------------------------- > commit 5e55aa8db085dad1aabb4574c73c23c7ae571e7b > Author: Dave Kleikamp > Date: Sun Oct 26 18:20:14 2008 -0400 > > sched_clock: prevent scd->clock from moving backwards > > commit 5b7dba4ff834259a5623e03a565748704a8fe449 upstream > > sched_clock: prevent scd->clock from moving backwards > > When sched_clock_cpu() couples the clocks between two cpus, it may > increment scd->clock beyond the GTOD tick window that __update_sched_clock() > uses to clamp the clock. A later call to __update_sched_clock() may move > the clock back to scd->tick_gtod + TICK_NSEC, violating the clock's > monotonic property. > > This patch ensures that scd->clock will not be set backward. > > Signed-off-by: Dave Kleikamp > Acked-by: Peter Zijlstra > Signed-off-by: Ingo Molnar > Cc: Chuck Ebbert > Signed-off-by: Greg Kroah-Hartman > ------------------------------------------------------------------------------------------------------------ > > Both 2.6.27.8 and 2.6.28-rc8 with that commit reverted work fine > (well, at least they failed to show the bug so far). Thanks for the update, I have put this information into the Bugzilla entry. Would everyone involved agree with reverting the above commit for now and revisiting the issue in the 2.6.29 time frame? Rafael From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752220AbYLMS6g (ORCPT ); Sat, 13 Dec 2008 13:58:36 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751251AbYLMS60 (ORCPT ); Sat, 13 Dec 2008 13:58:26 -0500 Received: from ogre.sisk.pl ([217.79.144.158]:40885 "EHLO ogre.sisk.pl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750919AbYLMS60 (ORCPT ); Sat, 13 Dec 2008 13:58:26 -0500 From: "Rafael J. Wysocki" To: "Fabio Comolli" Subject: Re: [Bug #12155] Regression in 2.6.28-rc and 2.6.27-stable - hibernate related Date: Sat, 13 Dec 2008 19:56:02 +0100 User-Agent: KMail/1.9.9 Cc: "Linux Kernel Mailing List" , "Kernel Testers List" , "Dave Kleikamp" , Peter Zijlstra , Ingo Molnar , "Greg Kroah-Hartman" , Chuck Ebbert , Linus Torvalds References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200812131956.03495.rjw@sisk.pl> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Saturday, 13 of December 2008, Fabio Comolli wrote: > Hi. Hi, > On Sat, Dec 13, 2008 at 5:33 PM, Rafael J. Wysocki wrote: > > This message has been generated automatically as a part of a report > > of recent regressions. > > > > The following bug entry is on the current list of known regressions > > from 2.6.27. Please verify if it still should be listed and let me know > > (either way). > > > > > > Bug-Entry : http://bugzilla.kernel.org/show_bug.cgi?id=12155 > > Subject : Regression in 2.6.28-rc and 2.6.27-stable - hibernate related > > Submitter : Fabio Comolli > > Date : 2008-11-23 16:17 (21 days old) > > References : http://marc.info/?l=linux-kernel&m=122745709926361&w=4 > > Still present. It has been bisected to: > > --------------------------------------------------------------------------------------------------------------- > commit 5e55aa8db085dad1aabb4574c73c23c7ae571e7b > Author: Dave Kleikamp > Date: Sun Oct 26 18:20:14 2008 -0400 > > sched_clock: prevent scd->clock from moving backwards > > commit 5b7dba4ff834259a5623e03a565748704a8fe449 upstream > > sched_clock: prevent scd->clock from moving backwards > > When sched_clock_cpu() couples the clocks between two cpus, it may > increment scd->clock beyond the GTOD tick window that __update_sched_clock() > uses to clamp the clock. A later call to __update_sched_clock() may move > the clock back to scd->tick_gtod + TICK_NSEC, violating the clock's > monotonic property. > > This patch ensures that scd->clock will not be set backward. > > Signed-off-by: Dave Kleikamp > Acked-by: Peter Zijlstra > Signed-off-by: Ingo Molnar > Cc: Chuck Ebbert > Signed-off-by: Greg Kroah-Hartman > ------------------------------------------------------------------------------------------------------------ > > Both 2.6.27.8 and 2.6.28-rc8 with that commit reverted work fine > (well, at least they failed to show the bug so far). Thanks for the update, I have put this information into the Bugzilla entry. Would everyone involved agree with reverting the above commit for now and revisiting the issue in the 2.6.29 time frame? Rafael