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Subject: Re: Strange segmentation violations of rpc.gssd in Debian Buster
To:     "Kraus, Sebastian" <sebastian.kraus@tu-berlin.de>,
        "J. Bruce Fields" <bfields@fieldses.org>
Cc:     "linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>
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 <20200620170316.GH1514@fieldses.org>
 <5c45562c90404838944ee71a1d926c74@tu-berlin.de>
 <20200622223628.GC11051@fieldses.org>
 <406fe972135846dc8a23b60be59b0590@tu-berlin.de>
From:   Doug Nazar <nazard@nazar.ca>
Message-ID: <1527b158-3404-168c-8908-de4b8a709ccd@nazar.ca>
Date:   Thu, 25 Jun 2020 17:44:14 -0400
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On 2020-06-25 13:43, Kraus, Sebastian wrote:
> [Current thread is 1 (Thread 0x7fb2eaeba700 (LWP 14174))]
> (gdb) bt
> #0  0x000056233fff038e in ?? ()
> #1  0x000056233fff09f8 in ?? ()
> #2  0x000056233fff0b92 in ?? ()
> #3  0x000056233fff13b3 in ?? ()
> #4  0x00007fb2eb8dbfa3 in start_thread (arg=<optimized out>) at pthread_create.c:486
> #5  0x00007fb2eb80c4cf in clone () at ../sysdeps/unix/sysv/linux/x86_64/clone.S:95
> (gdb) quit
>
>
> I am not an expert in analyzing stack and backtraces. Is there anything meaningful, you are able to extract from the trace?
> As far as I see, thread 14174 caused the segmentation violation just after its birth on clone.
> Please correct me, if I am in error.
> Seems Debian Buster does not ship any dedicated package with debug symbols for the rpc.gssd executable.
> So far, I was not able to find such a package.
> What's your opinon about the trace?

You'll need to install the debug symbols for your distribution/package. 
A quick google links to https://wiki.debian.org/HowToGetABacktrace. 
Those ?? lines should then be replaced with function, file & line numbers.

I've been following this with interest since it used to happen to me a 
lot. It hasn't recently, even though every so often I spend a few hours 
trying to re-create it to try debug it.

Doug