Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751633AbdFIM0n (ORCPT ); Fri, 9 Jun 2017 08:26:43 -0400 Received: from merlin.infradead.org ([205.233.59.134]:36328 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751542AbdFIM0l (ORCPT ); Fri, 9 Jun 2017 08:26:41 -0400 Date: Fri, 9 Jun 2017 14:26:21 +0200 From: Peter Zijlstra To: "Levin, Alexander (Sasha Levin)" Cc: Frederic Weisbecker , Thomas Gleixner , Ingo Molnar , LKML , Rik van Riel , James Hartsock , "stable@vger.kernel.org" , Tim Wright , Pavel Machek Subject: Re: [PATCH] nohz: Fix spurious warning when hrtimer and clockevent get out of sync Message-ID: <20170609122621.hptdcosdf6ptohta@hirez.programming.kicks-ass.net> References: <20170603124237.GA25077@lerouge> <20170603125259.scyapxq2fftqiiz3@sasha-lappy> <20170606145227.GB22016@lerouge> <20170607040801.4r7iqfzynf3d3xom@sasha-lappy> <20170607141400.GA29571@lerouge> <20170607213349.wtc2xhljlx5zjv5f@sasha-lappy> <20170608190702.GB27757@lerouge> <20170608221336.vem2i3364sljme4n@sasha-lappy> <20170609004853.GA27190@lerouge> <20170609121346.km66edd6v2sjinhc@sasha-lappy> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170609121346.km66edd6v2sjinhc@sasha-lappy> User-Agent: NeoMutt/20170113 (1.7.2) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1376 Lines: 29 On Fri, Jun 09, 2017 at 12:13:49PM +0000, Levin, Alexander (Sasha Levin) wrote: > On Fri, Jun 09, 2017 at 02:48:57AM +0200, Frederic Weisbecker wrote: > > On Thu, Jun 08, 2017 at 10:13:38PM +0000, Levin, Alexander (Sasha Levin) wrote: > > > On Thu, Jun 08, 2017 at 09:07:05PM +0200, Frederic Weisbecker wrote: > > > > Awesome, these traces have been very helpful! So now I think I get what's going on. > > > > Can you please test the following fix? > > > > > > With the patch, I hit the warning early on boot: > > > > > > [ 1.423727] clocksource: Switched to clocksource kvm-clock > > > [ 1.429326] ------------[ cut here ]------------ > > > [ 1.430234] WARNING: CPU: 1 PID: 0 at kernel/time/tick-sched.c:792 __tick_nohz_idle_enter+0xe1c/0x15c0 > > > > Oh sorry, I inverted some conditional. It warns as soon as the tick is completely stopped > > and not just deferred, which seldom happen on my testbox. > > > > I need to learn programming again. > > > > Here is the fixed version: > > These warnings seem to have gone away, but I've started seeing a new one: > > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 12525 at kernel/time/hrtimer.c:805 hrtimer_forward+0x222/0x3e0 kernel/time/hrtimer.c:805 > Kernel panic - not syncing: panic_on_warn set ... https://lkml.kernel.org/r/20170609104457.GA39907@inn.lkp.intel.com has a very similar splat