daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: mysqld got signal 11;
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: This could be because you hit a bug. It is also possible that this binary
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: or one of the libraries it was linked against is corrupt, improperly built,
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: or misconfigured. This error can also be caused by malfunctioning hardware.
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: We will try our best to scrape up some info that will hopefully help diagnose
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: the problem, but since we have already crashed, something is definitely wrong
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: and this may fail.
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: key_buffer_size=16777216
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: read_buffer_size=2093056
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: max_used_connections=37
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: max_connections=100
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: threads_connected=18
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: It is possible that mysqld could use up to 
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: key_buffer_size + (read_buffer_size + sort_buffer_size)*max_connections = 1039983 K
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: bytes of memory
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: Hope that's ok; if not, decrease some variables in the equation.
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: thd=0xaf9b420
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: Attempting backtrace. You can use the following information to find out
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: where mysqld died. If you see no messages after this, something went
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: terribly wrong...
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: Cannot determine thread, fp=0x23ed5d78, backtrace may not be correct.
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: Stack range sanity check OK, backtrace follows:
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0x81ba944
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0xffffe420
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0xb0638f4
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0x81d35a8
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0x8227620
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0x82263ea
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0x81ce7fd
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0x81cd37d
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0x81cc812
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0xb7f5ab63
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: 0xb7dd218a
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: New value of fp=(nil) failed sanity check, terminating stack trace!
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: Please read http://dev.mysql.com/doc/mysql/en/Using_stack_trace.html and follow instructions on how to resolve the stack trace. Resolved
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: stack trace is much more helpful in diagnosing the problem, so please do 
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: resolve it
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: Trying to get some variables.
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: Some pointers may be invalid and cause the dump to abort...
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: thd->query at 0xb0613b0 = DELETE FROM share_network  USING share_network,        (friends AS f         RIGHT JOIN share_network AS s         ON f.owner_username=s.username AND            f.username=s.shares_with)  WHERE share_network.username=s.username AND        share_network.shares_with=s.shares_with AND        f.owner_username IS NULL
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: thd->thread_id=24
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: The manual page at http://www.mysql.com/doc/en/Crashing.html contains
daemon.log.1:Oct 15 22:58:23 uk2-host2 mysqld[9353]: information that should help you find out what is causing the crash.