Segfaults

Thu Jun 23 14:21:20 UTC 2016

Hi Christian, 

I looked and there is no log for apport in /var/log/. Also I check dmesg and I 
now see this error. 

[2920471.605928] mdadm[26249]: segfault at 8 ip 00007f6cb8f0ed16 sp 
00007fffd5bb20e8 error 4 in libc-2.23.so[7f6cb8e84000+1c0000] 
[2920471.606068] Core dump to |/usr/share/apport/apport 15730 11 0 26249 pipe 
failed 

Which is different than before. I have never seen the core dump error before. 
Any ideas on what that means? Sounds like apport isn't working correctly. 

Thanks! 

Tyler 

----- Original Message -----

From: "Christian Ehrhardt" <christian.ehrhardt at canonical.com> 
To: "Tyler Petersen" <tpetersen at xes-inc.com> 
Cc: "ubuntu-server" <ubuntu-server at lists.ubuntu.com> 
Sent: Thursday, June 23, 2016 1:08:09 AM 
Subject: Re: Segfaults 

Hi Tyler, 
well in that case we have to find why your apport isn't collecting the crash, because that is the start to look deeper into it. 
There is /var/log/apport* which might help you to understand what is going on. 

I quickly ran this: 
#include <signal.h> 
int main() 
{ 
raise(SIGSEGV); 
} 

And got: 
cat /var/log/apport.log 
ERROR: apport (pid 26269) Thu Jun 23 07:50:47 2016: called for pid 26268, signal 11, core limit 0 
ERROR: apport (pid 26269) Thu Jun 23 07:50:47 2016: executable: /tmp/segfaultme (command line "./segfaultme") 
ERROR: apport (pid 26269) Thu Jun 23 07:50:47 2016: executable does not belong to a package, ignoring 

Well that is fair, but at least it picked up the fault happening for sure. 

Next I let something segfault that is in a package 
md5sum /dev/urandom & 
kill --signal SIGSEGV $! 

Here I already got my "there was a crash popup by apport" since I'm on a desktop. 
In the log I found: 
ERROR: apport (pid 28384) Thu Jun 23 08:01:01 2016: called for pid 28159, signal 11, core limit 0 
ERROR: apport (pid 28384) Thu Jun 23 08:01:01 2016: executable: /usr/bin/md5sum (command line "md5sum /dev/urandom") 
ERROR: apport (pid 28384) Thu Jun 23 08:01:01 2016: gdbus call error: Error: GDBus.Error:org.freedesktop.DBus.Error.ServiceUnknown: The name org.gnome.SessionManager was not provided by any .service files 
ERROR: apport (pid 28384) Thu Jun 23 08:01:01 2016: debug: session gdbus call: 
ERROR: apport (pid 28384) Thu Jun 23 08:01:02 2016: wrote report /var/crash/_usr_bin_md5sum.1000.crash 

Debugging starts like: 
sudo apport-retrace --stdout --rebuild-package-info /var/crash/_usr_bin_md5sum.1000.crash 
sudo apport-retrace --rebuild-package-info --gdb /var/crash/_usr_bin_md5sum.1000.crash 

I hope that helps to find why crashes aren't collected for you and then also about the first few steps into debugging if you like. 

Christian Ehrhardt 
Software Engineer, Ubuntu Server 
Canonical Ltd 

On Wed, Jun 22, 2016 at 9:45 PM, Tyler Petersen < tpetersen at xes-inc.com > wrote: 

Hi everyone, 

I am still having problems with this. I made sure apport was running and the /var/crash directory exists. But when 
a segfault happens nothing is written to the directory. The segfaults also seem to come and go. 

Thanks, 

Tyler 

From: "Christian Ehrhardt" < christian.ehrhardt at canonical.com > 
To: "Tyler Petersen" < tpetersen at xes-inc.com > 
Cc: "ubuntu-server" < ubuntu-server at lists.ubuntu.com > 
Sent: Wednesday, June 15, 2016 10:47:37 AM 
Subject: Re: Segfaults 

Hi Tyler, 
when an appliaction is crashing it should leave a .crash file in /var/crash which stores debugging information. 
Base on that you can automatically report a bug that has most of the info to start with. 
See https://help.ubuntu.com/community/ReportingBugs#Crash_reports for more. 

If you want to look into it more yourself I'd recommend starting with 
https://wiki.ubuntu.com/DebuggingProgramCrash 
https://www.piware.de/2011/08/apport-retrace-made-useful/ 

Kind regards, 
Christian 

Christian Ehrhardt 
Software Engineer, Ubuntu Server 
Canonical Ltd 

On Wed, Jun 15, 2016 at 3:55 PM, Tyler Petersen < tpetersen at xes-inc.com > wrote: 

<blockquote>

Hi everyone, 
We are currently experiencing some odd issues on our ubuntu servers (14.04). We 
keep seeing segfault messages for mdadm but we are not sure if they are a bug or 
a real problem. The servers are two completely different physical boxes. Both 
are running the 3.13.0-88-generic kernal and mdadm version 3.2.5-5ubuntu4.3. 
Here are the two most common errors we see: "[2201076.898901] mdadm[17298]: 
segfault at 8 ip 00007f3445891d16 sp 00007ffc2cd425f8 error 4 in 
libc-2.23.so [7f3445807000+1c0000]" and "[39304.894195] mdadm[17613]: segfault at 
0 ip 00007fb29477cd16 sp 00007ffe8ce211d8 error 4 in 
libc-2.23.so [7fb2946f2000+1c0000]". Any help or advice would be greatly 
apperciated. 
Thanks, 
Tyler 

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</blockquote>

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