ORA-600 [KGHLKREM1] On Linux Using Parameter drop_cache On hugepages Configuration

(Doc ID 1070812.1)

Last updated on APRIL 23, 2015

Applies to:

Oracle Database - Enterprise Edition - Version and later
Generic Linux
***Checked for relevance on 29-Jul-2013***


You are running an Oracle Database, single-instance or RAC. You have the SGA backed by hugepages.
You are getting the error

ORA-00600: internal error code, arguments: [KGHLKREM1], [0x06BC00020]
with stack trace similar to: kghnerror kghadd_reserved_ext kghgex

-- or also

ORA-07445: exception encountered: core dump
[kglhdal()+1105][SIGSEGV] [Address not mapped to object] [0x000000008] [] []

ORA-07445: exception encountered: core dump [kghfnd()+2328] [SIGSEGV]
[Address not mapped to object] [0xFFFFFFFFFFFFFFF0] [] []

Also the SGA heap Dump of memory around the offending addr (in this particular example: 0x6bc00020) shows it is zeroed out:

*** 2010-02-08 15:57:38.274
***** Internal heap ERROR KGHLKREM1 addr=0x6c400020 ds=0x60000058 *****
***** Dump of memory around addr 0x6c400020:
06C3FF020 00000000 00000000 00000000 00000000 [................]
Repeat 511 times


1. On your system you are running with vm.drop_caches=1 (or 3), drop_cache have been set to a value greater than zero , or you are executing

echo 3 > /proc/sys/vm/drop_caches


/proc/sys/vm/drop_caches (since Linux 2.6.16)
Writing to this file causes the kernel to drop clean caches, dentries and inodes from memory, causing that memory to become free.

To free pagecache:

* echo 1 > /proc/sys/vm/drop_caches

To free dentries and inodes:

* echo 2 > /proc/sys/vm/drop_caches

To free pagecache, dentries and inodes:

* echo 3 > /proc/sys/vm/drop_caches

As this is a non-destructive operation, and dirty objects are not freeable, the user should run "sync" first in order to make sure all cached objects are freed.

2. You have setup the Hugepages


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