Last updated on APRIL 23, 2015
Applies to:
Oracle Database - Enterprise Edition - Version 10.2.0.1 and laterGeneric Linux
***Checked for relevance on 29-Jul-2013***
Symptoms
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] [] []
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:
asm1_lmd0_8600.trc
~~~~~~~~~~~~~~~~~~
*** 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
~~~~~~~~~~~~~~~~~~
*** 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
Changes
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.
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
Cause
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