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Subject: Re: [PATCH] x86: fix duplicate calls of the nmi handler
From: Peter Zijlstra <peterz@infradead.org>
To: Robert Richter <robert.richter@amd.com>
Cc: Ingo Molnar <mingo@elte.hu>, Don Zickus <dzickus@redhat.com>,
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Date: Fri, 10 Sep 2010 18:15:16 +0200
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On Fri, 2010-09-10 at 17:56 +0200, Robert Richter wrote:
> On 10.09.10 10:46:34, Ingo Molnar wrote:
> > > > I'll look at getting a trace of the thing, but if any of you has
> a
> > > > bright idea...
> 
> I found another patch in my queue, which fixes a duplicate call of the
> nmi handler. Since I could not yet reproduce the bug, I am not sure if
> this fixes the problem, but it is worth a try.
> 
> 

           <...>-6114  [001]   340.053060: perf_event_nmi_handler: NMI-handled(1): 34833 27411 1
           <...>-6114  [001]   340.053061: perf_event_nmi_handler: NMI-stop: 34833 27411 1
           <...>-6114  [001]   340.053062: perf_event_nmi_handler: NMI: 34834 27411 1
           <...>-6114  [001]   340.053063: x86_pmu_handle_irq: OVERFLOW: 1
           <...>-6114  [001]   340.053064: x86_pmu_handle_irq: HANDLED: 1
           <...>-6114  [001]   340.053067: perf_event_nmi_handler: NMI-handled(1): 34834 27411 1
           <...>-6114  [001]   340.053068: perf_event_nmi_handler: NMI-stop: 34834 27411 1
           <...>-6114  [001]   340.053069: perf_event_nmi_handler: NMI: 34835 27411 1
           <...>-6114  [001]   340.053070: perf_event_nmi_handler: NMI-handled(0): 34835 27411 1
           <...>-6114  [001]   340.053071: perf_event_nmi_handler: NMI: 34835 27411 1
           <...>-6114  [001]   340.053072: perf_event_nmi_handler: NMI: 34835 27411 1
           <...>-6114  [001]   340.053073: perf_event_nmi_handler: NMI-fail


Nope.. it doesn't get tagged because handled == 1, not > 1.