Question

I’m trying to solve a segmentation fault. This message appears in my apache-error.log:

[notice] child pid 3979 exit signal
Segmentation fault (11)

I’ve tried disabling some apache and php modules but I’m still getting the same error.

I’ve also tried putting this in apache2.conf:

CoreDumpDirectory /tmp/apache2-gdb-dump

and then chmod 777, chown www-data… so that the server can write.

I can see no core-dump files to give me a hint on the error.

Does anybody have an idea why CoreDumpDirectory isn’t working on Ubuntu?

answers: $ ulimit -a
core file size
(blocks, -c) unlimited data seg size
(kbytes, -d) unlimited scheduling
priority (-e) 0 file size
(blocks, -f) unlimited pending signals
(-i) 15863 max locked memory
(kbytes, -l) 32 max memory size
(kbytes, -m) unlimited open files
(-n) 1024 pipe size (512
bytes, -p) 8 POSIX message queues
(bytes, -q) 819200 real-time priority
(-r) 0 stack size
(kbytes, -s) 8192 cpu time
(seconds, -t) unlimited max user
processes (-u) 15863
virtual memory (kbytes, -v)
unlimited file locks
(-x) unlimited

Answer 1

I finally was able to see Apache’s core dump in Ubuntu:

1. edit /etc/default/apport

2. edit apache2.conf:

     CoreDumpDirectory /tmp/apache2-gdb-dump
   

3. make sure Apache can write to it:

   # chmod 777 /tmp/apache2-gdb-dump
   

4. remove core dump size limit:

   # ulimit -c unlimited
   

5. Optionally, change the name pattern of the core dumps:

   # echo 'coredump-%e.%p' > /proc/sys/kernel/core_pattern
   

To analyse the dump use gdb:

$ gdb apache2 /tmp/apache2-gdb-dump/coredump-x.x

To see stacktrace details, in gdb:

gdb> where

This I did, and I obtained the core-dump.
However, my problem was not solved by looking at the coredump;
it was apparently an issue in my php script.

More info:
http://matrafox.info/apache-child-pid-exit-signal-segmentation-fault.html