Oracle DB fails to start with shared memory error: ORA-27137

Issue

• Oracle DB service failed to start with the following shared memory error:

SQL> startup;
ORA-27137: unable to allocate large pages to create a shared memory segment
Linux-x86_64 Error: 12: Cannot allocate memory

• The "Large Pages Information" section in the alert log has the following information:

****************** Large Pages Information *****************
Parameter use_large_pages = ONLY

Large Pages unused system wide = 0 (0 KB) (alloc incr 4096 KB)
Large Pages configured system wide = 0 (0 KB)
Large Page size = 2048 KB

ERROR:
  Failed to allocate shared global region with large pages, unix errno = 12.
  Aborting Instance startup.
  ORA-27137: unable to allocate Large Pages to create a shared memory segment

ACTION:
  Total Shared Global Region size is 800 GB. Increase the number of
  unused large pages to atleast 409604 (800 GB) to allocate 100% Shared Global
  Region with Large Pages.