From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S933832AbXGQRR0 (ORCPT ); Tue, 17 Jul 2007 13:17:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1758883AbXGQRRO (ORCPT ); Tue, 17 Jul 2007 13:17:14 -0400 Received: from rgminet01.oracle.com ([148.87.113.118]:38722 "EHLO rgminet01.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1759618AbXGQRRL (ORCPT ); Tue, 17 Jul 2007 13:17:11 -0400 Date: Tue, 17 Jul 2007 10:03:00 -0700 From: Randy Dunlap To: Ingo Molnar Cc: Jeremy Fitzhardinge , linux-kernel@vger.kernel.org, Andrew Morton , Linus Torvalds , stable@kernel.org, Greg KH , Chris Wright Subject: Re: [patch] fix the softlockup watchdog to actually work Message-Id: <20070717100300.821650f5.randy.dunlap@oracle.com> In-Reply-To: <20070717154934.GA24231@elte.hu> References: <20070717114453.GA8212@elte.hu> <469CCF8F.4010107@goop.org> <20070717154934.GA24231@elte.hu> Organization: Oracle Linux Eng. X-Mailer: Sylpheed 2.4.2 (GTK+ 2.8.10; x86_64-unknown-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Brightmail-Tracker: AAAAAQAAAAI= X-Brightmail-Tracker: AAAAAQAAAAI= X-Whitelist: TRUE X-Whitelist: TRUE Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 17 Jul 2007 17:49:34 +0200 Ingo Molnar wrote: > > * Jeremy Fitzhardinge wrote: > > > Ingo Molnar wrote: > > > Subject: softlockup: fix Xen bogosity > > > From: Ingo Molnar > > > > > > this Xen related commit: > > > > > > > Well, not just Xen. It relates to any virtual environment: kvm, > > lguest, vmi, xen... (Not that they all implement a measure of > > unstolen time.) > > > > How about a more descriptive patch title, along the lines of > > "softlockup watchdog: fix rate limiting"? > > uhm, the problem was that it did not work _at all_, not something about > 'rate limiting'. Yes, i got quite a bit grumpy when i found this, > because you completely broke the softlockup watchdog via a pretty > intrusive commit and you apparently didnt even do a minimal check > whether its functionality was preserved! Updated patch for Andrew/Linus > and for -stable attached. > > Ingo > > -----------------------------> > Subject: fix the softlockup watchdog to actually work > From: Ingo Molnar > > this Xen related commit: > > commit 966812dc98e6a7fcdf759cbfa0efab77500a8868 > Author: Jeremy Fitzhardinge > Date: Tue May 8 00:28:02 2007 -0700 > > Ignore stolen time in the softlockup watchdog > > broke the softlockup watchdog to never report any lockups. (!) > > print_timestamp defaults to 0, this makes the following condition > always true: > > if (print_timestamp < (touch_timestamp + 1) || > > and we'll in essence never report soft lockups. > > apparently the functionality of the soft lockup watchdog was never > actually tested with that patch applied ... > > [this is -stable material too.] > > Signed-off-by: Ingo Molnar > --- > kernel/softlockup.c | 7 ++++--- > 1 file changed, 4 insertions(+), 3 deletions(-) > > Index: linux/kernel/softlockup.c > =================================================================== > --- linux.orig/kernel/softlockup.c > +++ linux/kernel/softlockup.c > @@ -79,10 +79,11 @@ void softlockup_tick(void) > print_timestamp = per_cpu(print_timestamp, this_cpu); > > /* report at most once a second */ > - if (print_timestamp < (touch_timestamp + 1) || > - did_panic || > - !per_cpu(watchdog_task, this_cpu)) > + if ((print_timestamp >= touch_timestamp && > + print_timestamp < (touch_timestamp + 1)) || > + did_panic || !per_cpu(watchdog_task, this_cpu)) { > return; > + } > > /* do not print during early bootup: */ > if (unlikely(system_state != SYSTEM_RUNNING)) { patch contains unneeded braces { }. --- ~Randy *** Remember to use Documentation/SubmitChecklist when testing your code ***