linux-kernel - Re: [PATCHv2] perf: Fix vmalloc ring buffer free function

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Message-ID: <20130311121553.GB18098@gmail.com>
Date:	Mon, 11 Mar 2013 13:15:53 +0100
From:	Ingo Molnar <mingo@...nel.org>
To:	Jiri Olsa <jolsa@...hat.com>
Cc:	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	linux-kernel@...r.kernel.org,
	Corey Ashford <cjashfor@...ux.vnet.ibm.com>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Ingo Molnar <mingo@...e.hu>,
	Namhyung Kim <namhyung@...nel.org>,
	Paul Mackerras <paulus@...ba.org>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: Re: [PATCHv2] perf: Fix vmalloc ring buffer free function


* Jiri Olsa <jolsa@...hat.com> wrote:

> > >  struct page *
> > >  perf_mmap_to_page(struct ring_buffer *rb, unsigned long pgoff)
> > >  {
> > > -	if (pgoff > (1UL << page_order(rb)))
> > > +	if (pgoff > page_nr(rb))
> > >  		return NULL;
> > 
> > This is just wrong.. you have page_nr() be 1+2^n, but the comparison is
> 
> > '>' not '>=', this means we get a range of 2+2^n, not the desired 1+2^n.
> 
> ouch, missed that one

So, because this is perf/urgent which I want to send Linuswards, I removed 
the commit to not hold up other bits - please resend the whole patch once 
everything is fixed.

Thanks,

	Ingo
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