linux-kernel - Re: [PATCH -v3] perf, x86: try to handle unknown nmis with running perfctrs

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Date:	Wed, 25 Aug 2010 12:20:13 +0200
From:	Robert Richter <robert.richter@....com>
To:	Don Zickus <dzickus@...hat.com>
CC:	Cyrill Gorcunov <gorcunov@...il.com>, Ingo Molnar <mingo@...e.hu>,
	Peter Zijlstra <peterz@...radead.org>,
	Lin Ming <ming.m.lin@...el.com>,
	"fweisbec@...il.com" <fweisbec@...il.com>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	"Huang, Ying" <ying.huang@...el.com>,
	Yinghai Lu <yinghai@...nel.org>,
	Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH -v3] perf, x86: try to handle unknown nmis with running
 perfctrs

On 24.08.10 16:27:18, Don Zickus wrote:
> On Tue, Aug 24, 2010 at 11:52:40PM +0400, Cyrill Gorcunov wrote:
> > > I use 2.6.34 atm. Letme try 2.6.36 (which might require some time to recompile).
> > > 
> > > 	-- Cyrill
> > 
> > Don, for me it fails with somehow unrelated page handling fault - in
> > reiserfs_evict_inode O_o Fails in __get_cpu_var I suspect might means
> > a problem either in per-cpu allocator itself or we screw pointer somehow.
> > Weird.
> 
> I just found out (with the help of the crash utility and Dave A.) that
> Robert's percpu struct nmi clashes with the exception entry point .nmi.
> I only see this problem in 2.6.36, so I am not sure what changed with
> regards to compiler flags to confuse variables with text segments.

I was testing the patches also with CONFIG_LOCKUP_DETECTOR=y without
crashes.

> 
> But renaming the percpu struct nmi to nmidon fixed the problem for me (I
> am open to other suggestions :-) ).

Also I was looking at the differences between .35 and tip/perf/urgent
and could not find a namespace collision.

Hmm...

-Robert

-- 
Advanced Micro Devices, Inc.
Operating System Research Center

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