UEK3 - MEMORY LEAK OVER TIME DUE TO PSINFO_CACHE/SLAB (related memory) (Doc ID 2047851.1)

Last updated on JUNE 22, 2017

Applies to:

Linux OS - Version Oracle Linux 6.5 with Unbreakable Enterprise Kernel [3.8.13] and later
Oracle VM - Version 3.3.1 and later
Linux x86-64
Linux x86

Symptoms

The memory utilization on the Dom0 or Oracle Linux 6 server running UEK3 Kernel would show increase in memory usage over a period of time with swapping. Even without any major application/guests (running on dom0) the memory would increase over time and start to swap. 

 In addition to this, 'slabtop' can be used to check the details of slab usage. 

OBJS ACTIVE USE OBJ SIZE SLABS OBJ/SLAB CACHE SIZE NAME
145056 145056 100% 0.50K 18132 8 72528K size-512           <<<<<<<<<<<<<<<<<
192675 192675 100% 0.25K 12845 15 51380K size-256            <<<<<<<<<<<<<<<
341070 341070 100% 0.12K 11369 30 45476K psinfo_cache            <<<<<<<<<<<
156040 156040 100% 0.19K 7802 20 31208K dentry
30844 30844 100% 0.91K 7711 4 30844K ext4_inode_cache
689920 689808 99% 0.03K 6160 112 24640K size-32
217782 215056 98% 0.10K 5886 37 23544K buffer_head

 

 

In all tests where memory usage increases, there is a build up of "psinfo_cache" structures over time. These structures are allocated in the slab and are a contributor in the overall "SUnreClaim" memory usage.

Also SUnreclain accounts for the bulk of the overall memory usage increase during these tests, along with "generic purpose" slabs (size-192, size-32, etc.).

Changes

 

Cause

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