Re: [PATCH 03/10] mm/migrate: update node demotion order during on hotplug events

[David Hildenbrand]

On 09.04.21 12:14, Oscar Salvador wrote:
> On Thu, Apr 08, 2021 at 11:52:51AM +0200, Oscar Salvador wrote:
> > I am not really into PMEM, and I ignore whether we need
> > CONFIG_MEMORY_HOTPLUG in order to have such memory on the system.
> > If so, the following can be partly ignored.
>
> Ok, I refreshed by memory with [1].
>  From that, it seems that in order to use PMEM as RAM we need CONFIG_MEMORY_HOTPLUG.
> But is that always the case? Can happen that in some scenario PMEM comes ready
> to use and we do not need the hotplug trick?

The only way to add more System RAM is via add_memory() and friends like 
add_memory_driver_managed(). These all require CONFIG_MEMORY_HOTPLUG.

Memory ballooning is a different case, but there we're only adjusting 
the managed page counters.

--
Thanks,

David / dhildenb