Re: x86_pmu_start WARN_ON.

[Vince Weaver]

and the perf_fuzzer overnight triggered this possibly related warning
in x86_pmu_stop()

I assume it's this code (the line numbers don't match up for some reason).

        if (__test_and_clear_bit(hwc->idx, cpuc->active_mask)) {
                x86_pmu.disable(event);
                cpuc->events[hwc->idx] = NULL;
                WARN_ON_ONCE(hwc->state & PERF_HES_STOPPED);
                hwc->state |= PERF_HES_STOPPED;
        }

so possibly also related to PERF_HES_STOPPED?


[25526.987821] ------------[ cut here ]------------
[25526.988047] WARNING: CPU: 1 PID: 3849 at arch/x86/kernel/cpu/perf_event.c:1221 x86_pmu_stop+0x71/0xa6()
[25526.988047] Modules linked in: cpufreq_userspace cpufreq_stats cpufreq_powersave cpufreq_conservative f71882fg mcs7830 usbnet ohci_pci evdev video wmi psmouse serio_raw coretemp i2c_nforce2 ohci_hcd acpi_cpufreq processor pcspkr thermal_sys button sg ehci_pci ehci_hcd sd_mod usbcore usb_common
[25526.988047] CPU: 1 PID: 3849 Comm: perf_fuzzer Tainted: G        W    3.14.0-rc3+ #17
[25526.988047] Hardware name: AOpen   DE7000/nMCP7ALPx-DE R1.06 Oct.19.2012, BIOS 080015  10/19/2012
[25526.988047]  00000000000004c5 ffff88011fc83ca8 ffffffff81530d11 00000000000004c5
[25526.988047]  0000000000000000 ffff88011fc83ce8 ffffffff8103fce4 ffff88011fc83d28
[25526.988047]  ffffffff81012ca0 ffff8800c9be6000 0000000000000004 ffff88011fc8b940
[25526.988047] Call Trace:
[25526.988047]  <IRQ>  [<ffffffff81530d11>] dump_stack+0x49/0x60
[25526.988047]  [<ffffffff8103fce4>] warn_slowpath_common+0x81/0x9b
[25526.988047]  [<ffffffff81012ca0>] ? x86_pmu_stop+0x71/0xa6
[25526.988047]  [<ffffffff8103fd18>] warn_slowpath_null+0x1a/0x1c
[25526.988047]  [<ffffffff81012ca0>] x86_pmu_stop+0x71/0xa6
[25526.988047]  [<ffffffff81012e7b>] x86_pmu_del+0x3d/0xb8
[25526.988047]  [<ffffffff810ca936>] event_sched_out+0x92/0x121
[25526.988047]  [<ffffffff810cd124>] group_sched_in+0xf7/0x147
[25526.988047]  [<ffffffff810cd2d2>] ctx_sched_in+0x15e/0x185
[25526.988047]  [<ffffffff810cd362>] perf_event_sched_in+0x69/0x71
[25526.988047]  [<ffffffff810cd594>] perf_cpu_hrtimer_handler+0x13a/0x1b0
[25526.988047]  [<ffffffff8105e5b5>] __run_hrtimer+0xba/0x145
[25526.988047]  [<ffffffff810cd45a>] ? __perf_install_in_context+0xf0/0xf0
[25526.988047]  [<ffffffff8105e88a>] hrtimer_interrupt+0xd5/0x1c3
[25526.988047]  [<ffffffff8102b593>] local_apic_timer_interrupt+0x58/0x5d
[25526.988047]  [<ffffffff8102bf4f>] smp_trace_apic_timer_interrupt+0x53/0x91
[25526.988047]  [<ffffffff8153bafa>] trace_apic_timer_interrupt+0x6a/0x70
[25526.988047]  <EOI>  [<ffffffff8153ade6>] ? system_call_fastpath+0x1a/0x1f
[25526.988047] ---[ end trace d5252ca58550eb43 ]---

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