Out of memory problem

Hello, I am using the version 1.1.7 with authentication / accounting in mysql (rlm_sql). The problem is that the use of memory increasing until it is exhausted: dmesg messages: Out of Memory: Killed process 28272 (radiusd). Out of Memory: Killed process 1149 (radiusd). Out of Memory: Killed process 1155 (radiusd). The problem can only be solved restarting or reloading the radiusd. After restarting, the use of memory back to normal. It is a bug in version? Kernel problem ??? (kernel version is 2.6.15) Thanks Sorry for my english