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Description of problem:
RHEL7 has replaced its traditional memory allocator from CONFIG_SLAB to
CONFIG_SLUB. The "kmem -S" command displays statistics about the objects
in each per-cpu kmem_cache_cpu slab and about all of the per-node,
partially-used slabs. A change in the manner of bookkeeping was
introduced in Linux 3.1 that causes the object and in-use count of
those slabs to display incorrect data.
Version-Release number of selected component (if applicable):
crash-7.0.2-2.el7
How reproducible:
Always.
Steps to Reproduce:
1. Run "kmem -S" command.
2.
3.
Actual results:
For example, the slabs in the mm_struct kmem_cache each
have 15 total objects per-slab, but the "NODE 0 PARTIAL"
and "NODE 1 PARTIAL" listings show slabs with "TOTAL"
values that are equal to the "ALLOCATED" values, and
as a result, show "FREE" values of 0:
crash> kmem -S mm_struct
... [ cut ] ...
KMEM_CACHE_NODE NODE SLABS PARTIAL PER-CPU
ffff88022709b400 0 5 5 0
NODE 0 PARTIAL:
SLAB MEMORY NODE TOTAL ALLOCATED FREE
ffffea0008713e00 ffff88021c4f8000 0 2 2 0
ffffea000877e000 ffff88021df80000 0 0 0 0
ffffea000874b400 ffff88021d2d0000 0 0 0 0
ffffea0008742200 ffff88021d088000 0 5 5 0
ffffea000878ba00 ffff88021e2e8000 0 7 7 0
NODE 0 FULL:
(empty)
KMEM_CACHE_NODE NODE SLABS PARTIAL PER-CPU
ffff880426807400 1 4 4 0
NODE 1 PARTIAL:
SLAB MEMORY NODE TOTAL ALLOCATED FREE
ffffea00107a6e00 ffff88041e9b8000 1 4 4 0
ffffea0010802000 ffff880420080000 1 0 0 0
ffffea00107d5800 ffff88041f560000 1 3 3 0
ffffea00107cbc00 ffff88041f2f0000 1 5 5 0
NODE 1 FULL:
(empty)
crash>
Expected results:
The TOTAL values should all be 15, with corrected FREE counts.
Additional info:
This request was resolved in Red Hat Enterprise Linux 7.0.
Contact your manager or support representative in case you have further questions about the request.