Re: [Patch 2/2]: powerpc/hotplug/mm: Fix hot-add memory node assoc

[Reza Arbab]

On Thu, May 25, 2017 at 04:19:53PM +1000, Michael Ellerman wrote:
> The commit message for 3af229f2071f says:
>
>    In practice, we never see a system with 256 NUMA nodes, and in fact, we
>    do not support node hotplug on power in the first place, so the nodes
>    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
>    that are online when we come up are the nodes that will be present for
>    the lifetime of this kernel.
>
> Is that no longer true?

I don't know what the reasoning behind that statement was at the time, 
but as far as I can tell, the only thing missing for node hotplug now is 
Balbir's patchset [1]. He fixes the resource issue which motivated 
3af229f2071f and reverts it.

With that set, I can instantiate a new numa node just by doing 
add_memory(nid, ...) where nid doesn't currently exist.

[1] https://lkml.kernel.org/r/1479253501-26261-1-git-send-email-bsingharora@xxxxxxxxx

--
Reza Arbab