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Date: Mon, 01 Aug 2011 06:44:36 -0600
From: David Ahern <dsahern@gmail.com>
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To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH] perf: powerpc: Disable pagefaults during callchain stack
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Cc: Peter Zijlstra <peterz@infradead.org>, linux-kernel@vger.kernel.org,
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On 08/01/2011 04:39 AM, Benjamin Herrenschmidt wrote:
> On Mon, 2011-08-01 at 11:59 +0200, Peter Zijlstra wrote:
>>> Signed-off-by: David Ahern <dsahern@gmail.com>
>>> CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
>>> CC: Anton Blanchard <anton@samba.org> 
>>
>> Hmm, Paul, didn't you fix something like this early on? Anyway, I've
>> no
>> objections since I'm really not familiar enough with the PPC side of
>> things. 
> 
> I'm travelling so I haven't had a chance to review properly or even test
> but it looks like an ad-hoc fix for the immediate problem.
> 
> Ultimately, I want to rework that stuff to do a __gup_fast like x86 does
> (maybe as a fallback from an attempt at access first) so we work around
> access permissions blocked by lack of dirty/accessed bits but in the
> meantime, this should fix the immediate issue.

The problem goes back to all kernel releases with perf, so this patch
should get applied to the stable trains too.

David

> 
> Cheers,
> Ben.
> 
>