[PATCH] powerpc/pseries: Perform full re-add of CPU for topology update post-migration

[Michael Bringmann]

On 1/29/19 3:37 AM, Michael Ellerman wrote:
> Michael Bringmann <mwb at linux.vnet.ibm.com> writes:
> 
>> On 10/29/18 1:43 PM, Nathan Fontenot wrote:
>>> On pseries systems, performing a partition migration can result in
>>> altering the nodes a CPU is assigned to on the destination system. For
>>> exampl, pre-migration on the source system CPUs are in node 1 and 3,
>>> post-migration on the destination system CPUs are in nodes 2 and 3.
>>>
>>> Handling the node change for a CPU can cause corruption in the slab
>>> cache if we hit a timing where a CPUs node is changed while cache_reap()
>>> is invoked. The corruption occurs because the slab cache code appears
>>> to rely on the CPU and slab cache pages being on the same node.
>>>
>>> The current dynamic updating of a CPUs node done in arch/powerpc/mm/numa.c
>>> does not prevent us from hitting this scenario.
>>>
>>> Changing the device tree property update notification handler that
>>> recognizes an affinity change for a CPU to do a full DLPAR remove and
>>> add of the CPU instead of dynamically changing its node resolves this
>>> issue.
>>>
>>> Signed-off-by: Nathan Fontenot <nfont at linux.vnet.ibm.com
>> Signed-off-by: Michael W. Bringmann <mwb at linux.vnet.ibm.com>

Tested-by: Michael W. Bringmann <mwb at linux.vnet.ibm.com>

> 
> Are you sure that's what you meant? ie. you wrote some of the patch?
> 
> What I'd like is to get a Tested-by from you.
> 
> cheers
> 
> 

-- 
Michael W. Bringmann
Linux Technology Center
IBM Corporation
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External: (512) 286-5196
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mwb at linux.vnet.ibm.com