linux-kernel - Re: x86_pmu_start WARN

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Message-ID: <alpine.DEB.2.10.1402101620170.29602@vincent-weaver-1.um.maine.edu>
Date:	Mon, 10 Feb 2014 16:26:29 -0500 (EST)
From:	Vince Weaver <vincent.weaver@...ne.edu>
To:	Dave Jones <davej@...hat.com>,
	Linux Kernel <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>,
	Ingo Molnar <mingo@...hat.com>,
	Paul Mackerras <paulus@...ba.org>
Subject: Re: x86_pmu_start WARN_ON.

On Thu, 30 Jan 2014, Dave Jones wrote:

> I gave Vince's perf_fuzzer a run, hoping to trigger a different perf bug
> that I've been seeing. Instead I hit a different bug.

I've been seeing that WARN_ON for months but it was hard to reproduce.
After a lot of hassle (and scores or reboots) I managed to narrow this to 
a small test case.

Unfortunately it only reproduces on my core2 machine.  My ivb machine 
won't trigger it because it doesn't support PERF_COUNT_HW_INSTRUCTIONS
when precise_ip=1; is set.

This is with 3.14-rc2

The test case is attached, the warning message from my machine is below.

Vince

[   47.296031] ------------[ cut here ]------------
[   47.300013] WARNING: CPU: 0 PID: 2821 at arch/x86/kernel/cpu/perf_event.c:1076 x86_pmu_start+0x46/0xee()
[   47.300013] Modules linked in: cpufreq_userspace cpufreq_stats cpufreq_powersave cpufreq_conservative f71882fg mcs7830 usbnet evdev ohci_pci ohci_hcd pcspkr i2c_nforce2 psmouse serio_raw coretemp video wmi button acpi_cpufreq processor thermal_sys ehci_pci ehci_hcd sg sd_mod usbcore usb_common
[   47.300013] CPU: 0 PID: 2821 Comm: out Not tainted 3.14.0-rc2 #2
[   47.300013] Hardware name: AOpen   DE7000/nMCP7ALPx-DE R1.06 Oct.19.2012, BIOS 080015  10/19/2012
[   47.300013]  0000000000000000 ffffffff817f25ad ffffffff814e746b 0000000000000000
[   47.300013]  ffffffff8103bf1c ffff880037e62420 ffffffff81012126 ffff88011fc13400
[   47.300013]  ffff88011b2b1800 ffff88011fc0b940 0000000000000021 0000000000000000
[   47.300013] Call Trace:
[   47.300013]  [<ffffffff814e746b>] ? dump_stack+0x41/0x56
[   47.300013]  [<ffffffff8103bf1c>] ? warn_slowpath_common+0x79/0x92
[   47.300013]  [<ffffffff81012126>] ? x86_pmu_start+0x46/0xee
[   47.300013]  [<ffffffff81012126>] ? x86_pmu_start+0x46/0xee
[   47.300013]  [<ffffffff810123a1>] ? x86_pmu_enable+0x1d3/0x285
[   47.300013]  [<ffffffff810bca0d>] ? perf_event_context_sched_in+0x6d/0x8d
[   47.300013]  [<ffffffff810bca4e>] ? __perf_event_task_sched_in+0x21/0x108
[   47.300013]  [<ffffffff810666bc>] ? idle_balance+0x11a/0x157
[   47.300013]  [<ffffffff810628f5>] ? finish_task_switch+0x40/0xa5
[   47.300013]  [<ffffffff814e7e45>] ? __schedule+0x46a/0x4bd
[   47.300013]  [<ffffffff814e749d>] ? schedule_timeout+0x1d/0xb4
[   47.300013]  [<ffffffff8108bba6>] ? generic_exec_single+0x3f/0x52
[   47.300013]  [<ffffffff8102f017>] ? perf_reg_value+0x4c/0x4c
[   47.300013]  [<ffffffff8108bd33>] ? smp_call_function_single+0xdc/0xf2
[   47.300013]  [<ffffffff814e7480>] ? dump_stack+0x56/0x56
[   47.300013]  [<ffffffff814e8587>] ? __wait_for_common+0xce/0x14a
[   47.300013]  [<ffffffff8106286d>] ? try_to_wake_up+0x19a/0x19a
[   47.300013]  [<ffffffff810a1b47>] ? get_tracepoint+0x20/0x53
[   47.300013]  [<ffffffff8107ea47>] ? T.944+0x1c8/0x1c8
[   47.300013]  [<ffffffff8107c9f9>] ? wait_rcu_gp+0x3f/0x46
[   47.300013]  [<ffffffff8107ca00>] ? wait_rcu_gp+0x46/0x46
[   47.300013]  [<ffffffff810b2014>] ? perf_trace_event_unreg+0x2e/0xbd
[   47.300013]  [<ffffffff810b20d1>] ? perf_trace_destroy+0x2e/0x3b
[   47.300013]  [<ffffffff810bc0bf>] ? __free_event+0x2d/0x52
[   47.300013]  [<ffffffff810bfdec>] ? perf_event_release_kernel+0x74/0x7b
[   47.300013]  [<ffffffff810bfe9d>] ? perf_release+0x10/0x14
[   47.300013]  [<ffffffff81105b03>] ? __fput+0xdf/0x1a4
[   47.300013]  [<ffffffff810538d9>] ? task_work_run+0x7f/0x96
[   47.300013]  [<ffffffff814f09f0>] ? int_signal+0x12/0x17
[   47.300013] ---[ end trace 9ccad2f02057baa8 ]---

View attachment "warning29.c" of type "TEXT/x-csrc" (8710 bytes)