linux-kernel - Re: [PATCH RFC] perf_counter: Don't swap contexts containing locked mutex

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Date:	Fri, 29 May 2009 13:17:30 +0200
From:	Peter Zijlstra <peterz@...radead.org>
To:	Paul Mackerras <paulus@...ba.org>
Cc:	Ingo Molnar <mingo@...e.hu>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] perf_counter: Don't swap contexts containing
 locked mutex

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.


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