Re: [PATCH 0/4] mm,memory_hotplug: allocate memmap from hotadded memory

Michal Hocko
2019-04-01T11:53:11Z

On Mon 01-04-19 09:59:36, Oscar Salvador wrote:
> On Fri, Mar 29, 2019 at 02:42:43PM +0100, Michal Hocko wrote:
> > Having a larger contiguous area is definitely nice to have but you also
> > have to consider the other side of the thing. If we have a movable
> > memblock with unmovable memory then we are breaking the movable
> > property. So there should be some flexibility for caller to tell whether
> > to allocate on per device or per memblock. Or we need something to move
> > memmaps during the hotremove.
>
> By movable memblock you mean a memblock whose pages can be migrated over when
> this memblock is offlined, right?

I am mostly thinking about movable_node kernel parameter which makes
newly hotpluged memory go into ZONE_MOVABLE and people do use that to
make sure such a memory can be later hotremoved.

--
Michal Hocko
SUSE Labs