Linux-x86_64 Error: 12

I faced with that error message on 12.1.0.2.0 EE version on RHEL6 Here are the error messages SQL> startup nomount; ORA-27126: unable to lock shared memory segment in core Linux-x86_64 Error: 12: Cannot allocate memory Additional information: 3894 Additional information: 2129923 Additional information: 6090752 Continue reading