LOCK_SGA can not use with AMM or ASMM

LOCK_SGA locks the entire SGA into physical memory. It is usually advisable to lock the SGA into real (physical) memory, especially if the use of virtual memory would include storing some of the SGA using disk space.

On 11gR2:

SQL> show parameter lock_sga

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
lock_sga boolean FALSE

SQL> show parameter memory_target

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
memory_target big integer 776M

SQL> ALTER SYSTEM SET LOCK_SGA=TRUE SCOPE=SPFILE;

System altered.

SQL> shutdown
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup
ORA-00847: MEMORY_TARGET/MEMORY_MAX_TARGET and LOCK_SGA cannot be set together

On 10gR2:

SQL> show parameter lock_sga

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
lock_sga boolean FALSE

SQL> show parameter sga_target

NAME TYPE VALUE
------------------------------------ ----------- ------------------------------
sga_target big integer 168M

SQL> ALTER SYSTEM SET LOCK_SGA=TRUE SCOPE=SPFILE;

System altered.

SQL> shutdown
Database closed.
Database dismounted.
ORACLE instance shut down.

SQL> startup
ORA-27102: out of memory
Linux-x86_64 Error: 12: Cannot allocate memory

If need to use LOCK_SGA -)
- To Disable the Use of Automatic Memory Management or Automatic Shared Memory Management and enable manual shared memory management
Or...
- Don't lock the SGA.