How to get user level stack trace of an application from system crash

[Shailendra Rana]

On 7 October 2015 at 14:10, Pranay Srivastava <pranjas at gmail.com> wrote:
> On Tue, Oct 6, 2015 at 11:23 AM, Shailendra Rana
> <shailendra.rana1982 at gmail.com> wrote:
>> Hi,
>>
>> I have an application which traps file events using fanotify, process
>> these events and gives a verdict to fanotify whether access to a file
>> is allowed or not. However, in some cases the verdict does not reach
>> fanotify and system freezes. In such a case I just have system crash
>> to analyze the issue.
>
> Do you've any specific steps? Which kernel version you are using?
>
>>
>> My question is that is it possible to get a user level stack trace of
>> an application using system crash ?
>>
>> Thanks and regards,
>> Shailendra
>>
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>
>
>
> --
>         ---P.K.S

Hi,

The application traps file events and send them over to other system
via TCP. This other machine is running a third party solution which
process these events and sends the verdict to the application which
passes on the same to fanotify based on which decision of access to a
file is made. I have seen this freeze issue in case of network
failures but those are identifiable. There are couple of cases
mentioned below which may lead to this.

1) The event is received by third party solution but it did not send
the verdict to the application. In that scenario need to notify this
third party for fixing the issue.
2) Verdict is received by an application but could not pass on the
same to fantiofy maybe it is stuck in an infinite loop. In this case I
need to work towards fixing my application.

In order to identify the correct root cause I would want to have a
user level stack trace of this application. Using crash tool I could
not figure out the same.

I am using 3.13.0-24-generic #47-Ubuntu.

Thanks and regards,
Shailendra