Re: [RFC PATCH] mm, memory_hotplug: support movable_node for hotplugable nodes

[Reza Arbab]

On Thu, Jun 01, 2017 at 05:38:38PM +0200, Michal Hocko wrote:
> On Thu 01-06-17 10:19:36, Reza Arbab wrote:
> > The x86 SRAT (or the dt, on other platforms) can describe memory as
> > hotpluggable. See memblock_mark_hotplug(). That's only for memory present at
> > boot, though.
>
> Yes but lose that information after the memblock is gone and numa fully
> initialized. Or can we reconstruct that somehow?

I'm not sure you'd have to. At boot time, those markings are used to 
determine the initial boundaries of ZONE_MOVABLE. So if you removed 
these memblocks, then readded them, they would still be in ZONE_MOVABLE.

> > He's saying that since the memory was added after boot, it is by 
> > definition hotpluggable. There's no need to check for that 
> > marking/description.
>
> Yes, but we do not know whether we are onlining memblocks from a boot
> time numa node or a fresh one which has been hotadded.

That's true.

--
Reza Arbab