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Date: Thu, 12 Sep 2013 22:49:10 +0200
From: Ingo Molnar <mingo@kernel.org>
To: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Arnaldo Carvalho de Melo <acme@infradead.org>,
        Peter Zijlstra <a.p.zijlstra@chello.nl>,
        Thomas Gleixner <tglx@linutronix.de>,
        Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [GIT PULL] perf fixes
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* Linus Torvalds <torvalds@linux-foundation.org> wrote:

> On Thu, Sep 12, 2013 at 1:33 PM, Ingo Molnar <mingo@kernel.org> wrote:
> >
> > Hm, just to make sure, are you running a (very fresh) kernel that has this
> > fix included:
> >
> > d008d5258e9c perf: Fix up MMAP2 buffer space reservation
> 
> I've rebooted about five times since that report, so I'm not sure..
> 
> [ Short time passes ]
> 
> Hmm. That "reproducible" error is no longer reproducible for me on 
> current git (68f0d9d92e54). So if you fixed something recently, it's 
> possible I was running a pre-perf-pull kernel and an after-perf-pull 
> "perf" binary.

Yeah, so I think prior merging d008d5258e9c you'd see those artifacts with 
new, MMAP2-aware perf tooling. Both older kernels would work fine with any 
version of the tooling, and old tooling would work fine. Only new tooling 
used on a kernel within the breakage window would be exposed to this.

I think the window of breakage is relatively small (you managed to hit 
it), but should we add a quirk for this?

Thanks,

	Ingo