Messages in this thread Patch in this message | | | Date | Mon, 6 Feb 2012 11:40:29 +0100 | Subject | Re: WARNING: at arch/x86/kernel/cpu/perf_event.c:989 | From | Stephane Eranian <> |
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On Mon, Feb 6, 2012 at 11:12 AM, Eric Dumazet <eric.dumazet@gmail.com> wrote: > Le lundi 06 février 2012 à 10:54 +0100, Stephane Eranian a écrit : >> On Sat, Feb 4, 2012 at 7:09 PM, Stephane Eranian <eranian@google.com> wrote: >> > I am working on it. It is hard to reproduce for me. >> > >> What did you run to trigger this warning? What system is this on? >> >> > On Sat, Feb 4, 2012 at 2:51 PM, Ingo Molnar <mingo@elte.hu> wrote: >> >> >> >> there's yet another one triggering at: >> >> >> >> [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 >> >> >> >> Thanks, >> >> >> >> Ingo > > Stephane, I trigger this as well very easily on my machine, 32bit > kernel, using the following : > > > perf record -a -g hackbench 10 thread 4000 > I tried that on my Nehalem 64-bit running 3.3.0-rc2 where I reverted that chunck of commit 84f2b9b:
--- a/arch/x86/kernel/cpu/perf_event.c +++ b/arch/x86/kernel/cpu/perf_event.c @@ -986,9 +986,6 @@ static void x86_pmu_start(struct perf_event *event, int flags) struct cpu_hw_events *cpuc = &__get_cpu_var(cpu_hw_events); int idx = event->hw.idx;
- if (WARN_ON_ONCE(!(event->hw.state & PERF_HES_STOPPED))) - return; - if (WARN_ON_ONCE(idx == -1)) return;
I have an explanation for the other two WARN_ON_ONCE() but not for that one. Friday, I was able to track this down to a situation where from unthr we call pmu->stop() but because the event is already marked as not active in cpuc->active_mask, PERF_HES_STOPPED is not set, then x86_pmu_start() complains. It happens during frequency adjustments and not unthrottling. This is odd because the only place where cpuc->active_mask is cleared (for the event) is x86_pmu_stop(). So looks like we get into a situation where cpuc->active_mask[b] == 0 && event->state != HES_STOPPED. But I don't know where this could happen.
> > [ 1205.338006] ------------[ cut here ]------------ > [ 1205.338028] WARNING: at arch/x86/kernel/cpu/perf_event.c:989 > x86_pmu_start+0xba/0xf0() > [ 1205.338044] Hardware name: ProLiant BL460c G1 > [ 1205.338053] Modules linked in: xt_hashlimit af_packet tg3 bonding > [ 1205.338076] Pid: 0, comm: swapper/5 Not tainted > 3.3.0-rc2-00172-g23783f8 #55 > [ 1205.338090] Call Trace: > [ 1205.338100] [<c0609e06>] ? printk+0x1d/0x1f > [ 1205.338111] [<c022b012>] warn_slowpath_common+0x72/0xa0 > [ 1205.338123] [<c021072a>] ? x86_pmu_start+0xba/0xf0 > [ 1205.338134] [<c021072a>] ? x86_pmu_start+0xba/0xf0 > [ 1205.338145] [<c022b062>] warn_slowpath_null+0x22/0x30 > [ 1205.338157] [<c021072a>] x86_pmu_start+0xba/0xf0 > [ 1205.338170] [<c02aba7b>] perf_adjust_freq_unthr_context.part.75 > +0xfb/0x180 > [ 1205.338185] [<c02abd21>] perf_event_task_tick+0x221/0x290 > [ 1205.338199] [<c0258dee>] ? update_cpu_load+0xbe/0xf0 > [ 1205.338210] [<c0259728>] scheduler_tick+0x98/0xf0 > [ 1205.338222] [<c0239c6a>] update_process_times+0x5a/0x70 > [ 1205.338235] [<c026bb10>] tick_sched_timer+0x60/0x1f0 > [ 1205.338248] [<c024f1c0>] ? __remove_hrtimer+0x40/0xa0 > [ 1205.338260] [<c024f3f7>] __run_hrtimer+0x67/0x1e0 > [ 1205.338270] [<c026bab0>] ? tick_init_highres+0x20/0x20 > [ 1205.338297] [<c02501b0>] hrtimer_interrupt+0xe0/0x260 > [ 1205.338323] [<c025c207>] ? sched_clock_cpu+0xd7/0x160 > [ 1205.338350] [<c025c841>] ? set_next_entity+0x31/0x70 > [ 1205.338380] [<c0610804>] smp_apic_timer_interrupt+0x54/0x88 > [ 1205.338407] [<c060fcda>] apic_timer_interrupt+0x2a/0x30 > [ 1205.338439] [<c0209efc>] ? mwait_idle+0x7c/0x1d0 > [ 1205.338470] [<c0201606>] cpu_idle+0x66/0xa0 > [ 1205.338495] [<c060500f>] start_secondary+0x1bf/0x1c5 > [ 1205.338520] ---[ end trace 94f790d96c8679f1 ]--- > [ 1211.617012] Uhhuh. NMI received for unknown reason 21 on CPU 0. > [ 1211.617049] Do you have a strange power saving mode enabled? > [ 1211.617075] Dazed and confused, but trying to continue > [ 1211.970013] Uhhuh. NMI received for unknown reason 31 on CPU 7. > [ 1211.970050] Do you have a strange power saving mode enabled? > [ 1211.970076] Dazed and confused, but trying to continue > [ 1214.440012] Uhhuh. NMI received for unknown reason 21 on CPU 3. > [ 1214.440048] Do you have a strange power saving mode enabled? > [ 1214.440074] Dazed and confused, but trying to continue > [ 1214.634012] Uhhuh. NMI received for unknown reason 31 on CPU 4. > [ 1214.634047] Do you have a strange power saving mode enabled? > [ 1214.634073] Dazed and confused, but trying to continue > [ 1216.568016] Uhhuh. NMI received for unknown reason 31 on CPU 1. > [ 1216.568052] Do you have a strange power saving mode enabled? > [ 1216.568078] Dazed and confused, but trying to continue > [ 1217.309010] Uhhuh. NMI received for unknown reason 31 on CPU 2. > [ 1217.309044] Do you have a strange power saving mode enabled? > [ 1217.309070] Dazed and confused, but trying to continue > > > > > processor : 7 > vendor_id : GenuineIntel > cpu family : 6 > model : 23 > model name : Intel(R) Xeon(R) CPU E5450 @ 3.00GHz > stepping : 6 > > -- 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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