After upgrading Grid Infrastructure from 11.2.0.1 to 11.2.0.2 on a single instance, you may observe huge amount of increase in disk usage due to core dump creation. You will see that a directory named like core_123 created every 10 minutes in <Grid_Home>/log/<host_name>/diskmon.

There is a bug numbered 10283819 in MOS considers the problem , however no workaround is provided. There are two ways you can follow to handle situation. First one is upgrading to 11.2.0.3. And the other one is uninstalling 11.2.0.1 completely, even remove the empty home, and restart all Oracle services.