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Subject: Re: [PATCH RFC] perf_counter: Don't swap contexts containing
 locked mutex
From: Peter Zijlstra <peterz@infradead.org>
To: Paul Mackerras <paulus@samba.org>
Cc: Ingo Molnar <mingo@elte.hu>, linux-kernel@vger.kernel.org
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Date: Fri, 29 May 2009 13:17:30 +0200
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On Fri, 2009-05-29 at 21:13 +1000, Paul Mackerras wrote:
> Ingo Molnar writes:
> 
> > looping in the remove-context retry loop.
> 
> Ah! We need to reload task inside the loop.  And possibly in other
> places.

Thing is, after your patch this is called after the unclone, so the
context should be stable, still we see this. But yeah that loop needs
some care.

I also noticed we have races on cpuctx->task_ctx, I was looking at
removing it alltogether in favour of current->perf_counter_ctxp.