linux-kernel - Re: [PATCH] perf top: fix crash on annotate request

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Date:	Fri, 16 Dec 2011 01:04:14 +0300
From:	Brian Gitonga Marete <marete@...hnix.com>
To:	Arnaldo Carvalho de Melo <acme@...radead.org>
Cc:	David Ahern <dsahern@...il.com>, linux-kernel@...r.kernel.org,
	mingo@...e.hu, peterz@...radead.org, fweisbec@...il.com
Subject: Re: [PATCH] perf top: fix crash on annotate request

On Fri, Dec 16, 2011 at 12:01 AM, Brian Gitonga Marete
<marete@...hnix.com> wrote:
> On Tue, Dec 6, 2011 at 4:44 PM, Arnaldo Carvalho de Melo
> <acme@...radead.org> wrote:
>>
>> Em Tue, Dec 06, 2011 at 10:22:57AM +0300, Brian Gitonga Marete escreveu:
>> > On Thu, Dec 1, 2011 at 5:11 PM, Arnaldo Carvalho de Melo <acme@...radead.org> wrote:
>> > > Its just this one, can you try doing something like:
>>
>> > > perf top -vvv > /tmp/debug.top 2>&1
>> > > bzip2 /tmp/debug.top
>>
>> > > That will print lots of information about symbols being loaded,
>> > > overlapping maps, etc that can help me understand why that symbol name
>> > > looks garbage.
>>
>> > > And send me in pvt the result together with a fresh backtrace with those
>> > > symbols printed? Also which distro are you using?
>>
>> > Hello Arnaldo. Curiously, I am unable to reproduce the crash when
>> > stdout is redirected to a file. I am able to capture lots of output if
>>
>> That is good input, so can you please try using just:
>>
>> perf top --stdio
>>
>> I.e. probably the problem is with the TUI code and running it in --stdio
>> mode will help us pinpoint that. No need to redirect anything.
>>
>
> Indeed `--stdio' avoids the crash. See my bisection report below.
>
>> > I redirect stdout to a file in verbose mode, but it won't crash when I
>> > do that. Just the same, I am still able to always reproduce (within a
>> > few seconds) with your perf/core branch on the tree you pointed me to.
>> > This time, I did a `thread apply all bt' in gdb to show the trace for
>> > the UI thread since it now seems to me to probably have something with
>> > the UI output (because I cannot reproduce if o/put is to a file). The
>> > trace is attached in the file gdb.txt.
>>
>> > Is the `perf top -vvv > /tmp/debug.top 2>&1' output useful even if it
>> > is captured in a session that does not crash? If so will send the
>> > output privately to you.
>>
>> please.
>
> Coming in a separate email to you.
>
>> > I am using Ubuntu 10.10
>>
>
> Hi. I have bisected this on Linus' tree and the commit that introduced
> the crash is: 8b1bfdbdb30
>
> commit 8b1bfdbdb3041c0503c42ef49bab25caabeaa558
> Author: Arnaldo Carvalho de Melo <acme@...hat.com>
> Date:   Wed Oct 5 19:41:31 2011 -0300
>
> perf top: Use the TUI interface by default
>
> It has to do with UI. Reverting it eliminates the crash. (As does
> using --stdio as I have said above)

Looking at the code, it seems that the connection between the TUI
interface and the core (where the crash occurs) is that the TUI
interface activates the annotation code which otherwise is not run. So
the bug is probably in the annotation code? Or in the version of the
binary (ELF) decoding libraries that are on my system -- Ubuntu 10.10

-- 
Brian Gitonga Marete
Toshnix Systems
Tel: +254722151590
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