Re: [PATCH v5 3/3] mm/page_alloc: Keep memoryless cpuless node 0 offline

From: David Hildenbrand
Date: Tue Aug 18 2020 - 03:33:15 EST


On 12.08.20 08:01, Srikar Dronamraju wrote:
> Hi Andrew, Michal, David
>
> * Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> [2020-08-06 21:32:11]:
>
>> On Fri, 3 Jul 2020 18:28:23 +0530 Srikar Dronamraju <srikar@xxxxxxxxxxxxxxxxxx> wrote:
>>
>>>> The memory hotplug changes that somehow because you can hotremove numa
>>>> nodes and therefore make the nodemask sparse but that is not a common
>>>> case. I am not sure what would happen if a completely new node was added
>>>> and its corresponding node was already used by the renumbered one
>>>> though. It would likely conflate the two I am afraid. But I am not sure
>>>> this is really possible with x86 and a lack of a bug report would
>>>> suggest that nobody is doing that at least.
>>>>
>>>
>>> JFYI,
>>> Satheesh copied in this mailchain had opened a bug a year on crash with vcpu
>>> hotplug on memoryless node.
>>>
>>> https://bugzilla.kernel.org/show_bug.cgi?id=202187
>>
>> So... do we merge this patch or not? Seems that the overall view is
>> "risky but nobody is likely to do anything better any time soon"?
>
> Can we decide on this one way or the other?

Hmm, not sure who's the person to decide. I tend to prefer doing the
node renaming, handling this in ppc code; looking at the review of v2
there are still some concerns regarding numa distances.

https://patchwork.ozlabs.org/project/linuxppc-dev/patch/20200817103238.158133-1-aneesh.kumar@xxxxxxxxxxxxx/

--
Thanks,

David / dhildenb