Re: [PATCH v5 1/5] mm,memory_hotplug: Allocate memmap from the added memory range

[David Hildenbrand]

On 24.03.21 13:10, Michal Hocko wrote:
> On Wed 24-03-21 13:03:29, Michal Hocko wrote:
> > On Wed 24-03-21 11:12:59, Oscar Salvador wrote:
> [...]
>
> an additional remark
>
> > > - online_pages()->move_pfn_range_to_zone(): Accounts for node/zone's spanned pages
> > > - online_pages()->zone->present_pages += nr_pages;
>
> I am pretty sure you shouldn't account vmmemmap pages to the target zone
> in some cases - e.g. vmemmap cannot be part of the movable zone, can it?
> So this would be yet another special casing. This patch has got it wrong
> unless I have missed some special casing.

It's a bit unfortunate that we have to discuss the very basic design 
decisions again.

@Oscar, maybe you can share the links where we discussed all this and 
add some of it to the patch description.

I think what we have right here is good enough for an initial version, 
from where on we can improve things without having to modify calling code.

--
Thanks,

David / dhildenb