Re: [PATCH] perf: powerpc: Disable pagefaults during callchain stack read

On 08/01/2011 04:39 AM, Benjamin Herrenschmidt wrote:

On Mon, 2011-08-01 at 11:59 +0200, Peter Zijlstra wrote:

quoted

quoted

Signed-off-by: David Ahern <redacted>
CC: Benjamin Herrenschmidt <benh@kernel.crashing.org>
CC: Anton Blanchard <redacted> 

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.