Re: [BUG] perf_event: crash in perf_output_begin

From: Stephane Eranian
Date: Mon May 10 2010 - 16:03:31 EST


On Mon, May 10, 2010 at 5:52 PM, Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
> On Mon, 2010-05-10 at 17:33 +0200, Stephane Eranian wrote:
>> Hi,
>>
>> While testing 2.6.34-rc7 I ran into the following issue when
>> using BTS sampling on Intel Core. It seems like something
>> is not terminated properly. I am sampling BTS per-thread
>> on a test program, then hit CTRL-C, one second later my
>> machine crashes while running bash. Crash dump below:
>>
>> [ Â750.249109] general protection fault: 0000 [#1] SMP
>> [ Â750.249270] CPU 3
>> [ Â750.249270] Pid: 6132, comm: bash Not tainted 2.6.34-rc7-tip+ #46
>
> Can you try and reverting 4fd38e4595e2f6c9d27732c042a0e16b2753049c, I
> spend most of the day chasing that, and I can't say I'm much wiser.
>

It seems to avoid my problem. So that means with STATE_FREE, some code
path is exercised differently and there is leftover state that
generates spurious
interrupts, as if some event_sched_out() code was not executed.
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