Messages in this thread | | | Date | Tue, 7 Feb 2012 10:17:12 +0100 | Subject | Re: [PATCH] perf: fix assertion failure in x86_pmu_start() | From | Stephane Eranian <> |
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On Tue, Feb 7, 2012 at 9:34 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote: > 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] <IRQ> [<ffffffff81065cc7>] warn_slowpath_common+0x7e/0x97 >> [89214.998379] [<ffffffff81065cf5>] warn_slowpath_null+0x15/0x17 >> [89215.004428] [<ffffffff8103f626>] x86_pmu_start+0x79/0xd4 >> [89215.010042] [<ffffffff810e30d1>] perf_adjust_freq_unthr_context.part.63+0xef/0x123 >> [89215.018123] [<ffffffff810e318c>] perf_event_task_tick+0x87/0x1c1 >> [89215.024463] [<ffffffff810a2370>] ? tick_nohz_handler+0xda/0xda >> [89215.030595] [<ffffffff8108b819>] scheduler_tick+0xd1/0xf3 >> [89215.036296] [<ffffffff810720b0>] update_process_times+0x5e/0x6f >> [89215.042512] [<ffffffff810a23e0>] tick_sched_timer+0x70/0x99 >> [89215.048387] [<ffffffff810823f9>] __run_hrtimer+0x8c/0x148 >> [89215.054087] [<ffffffff81082add>] 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 <eranian@google.com> >> --- > > This indeed fix the WARNING for me > > Acked-by: Eric Dumazet <eric.dumazet@gmail.com> > > But I still have these messages when doing a perf session. > > Machine seems to recover properly. > > Previous kernels were working without notice. > Doing what on what machine?
> [ 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 > > -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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