RESCIND Re: [v02] REPOST powerpc/migration: Handle unitialized timer reset

[Michael Bringmann]

Hello, Michael:
    I am an idiot this morning.  Not enough coffee.
I confused this posting with another.  Please forget the request.

    We do want to omit 

[PATCH v08 0/5] powerpc/hotplug: Update affinity for migrated CPUs
https://lists.ozlabs.org/pipermail/linuxppc-dev/2018-July/176301.html

though.

Very sorry for the inconvenience.

Michael

On 09/26/2018 09:44 AM, Michael Bringmann wrote:
> Hello, Michael:
>     Please look at v03 of the patch set which was posted
> just on 09/25/2018.  We had a last minute brainstorm of how
> to simplify the code after the v02 REPOST.
>     Also, note that we would like to invalidate the set,
> 
> [PATCH v08 0/5] powerpc/hotplug: Update affinity for migrated CPUs
> https://lists.ozlabs.org/pipermail/linuxppc-dev/2018-July/176301.html
> 
> as we think it is covered now by other code.
> 
>     Thanks for your attention and assistance.
> 
> Michael
> 
> On 09/26/2018 07:13 AM, Michael Ellerman wrote:
>> On Thu, 2018-09-20 at 16:45:13 UTC, Michael Bringmann wrote:
>>> After migration of a powerpc LPAR, the kernel executes code to
>>> update the system state to reflect new platform characteristics.
>>> Such changes include modifications to device tree properties
>>> provided to the system by PHYP.  Property notifications received
>>> by the powerpc 'migration_store' code are passed along to the
>>> kernel in general through a call to 'of_update_property' which
>>> in turn passes such events back to all modules through entries like
>>> the '.notifier_call' function within the NUMA module.  When the
>>> NUMA module updates its state, it resets its event timer.  If this
>>> occurs after a previous call to 'stop_topology_update' or on a
>>> system without VPHN enabled, the code runs into an unitialized
>>> timer structure and crashes.  This patch adds a safety check
>>> along this path toward the problem code.
>>>
>>> Note: This crash was observed on every LPM in the 4.17-rc7 kernel
>>> (and in the 4.18 kernel) of a system with dedicated CPUs enabled.
>>> An example crash log without the patch is as follows.
>>>
>> ...
>>>
>>> Signed-off-by: Michael Bringmann <mwb at linux.vnet.ibm.com>
>>
>> Applied to powerpc fixes, thanks.
>>
>> https://git.kernel.org/powerpc/c/8604895a34d92f5e186ceb931b0d1b
>>
>> 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