From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756703Ab2BGIe5 (ORCPT ); Tue, 7 Feb 2012 03:34:57 -0500 Received: from mail-we0-f174.google.com ([74.125.82.174]:50228 "EHLO mail-we0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755929Ab2BGIez (ORCPT ); Tue, 7 Feb 2012 03:34:55 -0500 Message-ID: <1328603689.2476.15.camel@edumazet-laptop> Subject: Re: [PATCH] perf: fix assertion failure in x86_pmu_start() From: Eric Dumazet To: Stephane Eranian Cc: linux-kernel@vger.kernel.org, mingo@elte.hu, peterz@infradead.org, markus@trippelsdorf.de, paulus@samba.org Date: Tue, 07 Feb 2012 09:34:49 +0100 In-Reply-To: <20120206205354.GA31186@quad> References: <20120206205354.GA31186@quad> Content-Type: text/plain; charset="UTF-8" X-Mailer: Evolution 3.2.2- Content-Transfer-Encoding: 8bit Mime-Version: 1.0 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Le lundi 06 février 2012 à 21:53 +0100, Stephane Eranian a écrit : > The following patch fixes an issue introduced by the following > commit: > e050e3f0a71b ("perf: Fix broken interrupt rate throttling") > > The patch caused the following warning to pop up depending on > the sampling frequency adjustments: > > [89214.962603] ------------[ cut here ]------------ > [89214.967441] WARNING: at arch/x86/kernel/cpu/perf_event.c:995 x86_pmu_start+0x79/0xd4() > [89214.975825] Hardware name: X8DTN > [89214.979268] Modules linked in: > [89214.982560] Pid: 0, comm: swapper/6 Not tainted 3.3.0-rc2-tip+ #1 > [89214.988865] Call Trace: > [89214.991533] [] warn_slowpath_common+0x7e/0x97 > [89214.998379] [] warn_slowpath_null+0x15/0x17 > [89215.004428] [] x86_pmu_start+0x79/0xd4 > [89215.010042] [] perf_adjust_freq_unthr_context.part.63+0xef/0x123 > [89215.018123] [] perf_event_task_tick+0x87/0x1c1 > [89215.024463] [] ? tick_nohz_handler+0xda/0xda > [89215.030595] [] scheduler_tick+0xd1/0xf3 > [89215.036296] [] update_process_times+0x5e/0x6f > [89215.042512] [] tick_sched_timer+0x70/0x99 > [89215.048387] [] __run_hrtimer+0x8c/0x148 > [89215.054087] [] hrtimer_interrupt+0xc1/0x18c > > It was caused by the following call sequence: > > perf_adjust_freq_unthr_context.part() { > stop() > if (delta > 0) { > perf_adjust_period() { > if (period > 8*...) { > stop() > ... > start() > } > } > } > start() > } > > Which caused a double start and a double stop, thus triggering the assert > in x86_pmu_start(). > > The patch fixes the problem by avoiding the double calls. We pass a new > argument to perf_adjust_period() to indicate whether or not the event > is already stopped. We can't just remove the start/stop from that function > because it's called from __perf_event_overflow where the event needs to > be reloaded via a stop/start back-toback call. > > The patch reintroduces the assertion in x86_pmu_start() which was removed > by commit: > 84f2b9b perf: Remove deprecated WARN_ON_ONCE() > > Signed-off-by: Stephane Eranian > --- This indeed fix the WARNING for me Acked-by: Eric Dumazet But I still have these messages when doing a perf session. Machine seems to recover properly. Previous kernels were working without notice. [ 300.553017] Uhhuh. NMI received for unknown reason 31 on CPU 2. [ 300.553071] Do you have a strange power saving mode enabled? [ 300.553115] Dazed and confused, but trying to continue [ 300.775014] Uhhuh. NMI received for unknown reason 31 on CPU 1. [ 300.775064] Do you have a strange power saving mode enabled? [ 300.775107] Dazed and confused, but trying to continue [ 303.250012] Uhhuh. NMI received for unknown reason 31 on CPU 0. [ 303.250067] Do you have a strange power saving mode enabled? [ 303.250110] Dazed and confused, but trying to continue [ 303.278012] Uhhuh. NMI received for unknown reason 31 on CPU 7. [ 303.278063] Do you have a strange power saving mode enabled? [ 303.278106] Dazed and confused, but trying to continue [ 305.839016] Uhhuh. NMI received for unknown reason 21 on CPU 5. [ 305.839068] Do you have a strange power saving mode enabled? [ 305.839112] Dazed and confused, but trying to continue [ 305.907013] Uhhuh. NMI received for unknown reason 31 on CPU 4. [ 305.907066] Do you have a strange power saving mode enabled? [ 305.907109] Dazed and confused, but trying to continue [ 306.953017] Uhhuh. NMI received for unknown reason 31 on CPU 1. [ 306.953069] Do you have a strange power saving mode enabled? [ 306.953111] Dazed and confused, but trying to continue [ 308.585014] Uhhuh. NMI received for unknown reason 31 on CPU 6. [ 308.585064] Do you have a strange power saving mode enabled? [ 308.585108] Dazed and confused, but trying to continue [ 309.239012] Uhhuh. NMI received for unknown reason 31 on CPU 0. [ 309.239079] Do you have a strange power saving mode enabled? [ 309.239137] Dazed and confused, but trying to continue [ 309.426009] Uhhuh. NMI received for unknown reason 21 on CPU 7. [ 309.426075] Do you have a strange power saving mode enabled? [ 309.426132] Dazed and confused, but trying to continue [ 309.592010] Uhhuh. NMI received for unknown reason 21 on CPU 2. [ 309.592076] Do you have a strange power saving mode enabled? [ 309.592133] Dazed and confused, but trying to continue