Re: [PATCH v1 0/3] mm/memory_hotplug: Export generic_online_page()

[Michal Hocko]

On Mon 23-09-19 14:20:05, David Hildenbrand wrote:
> On 23.09.19 14:07, Michal Hocko wrote:
> > On Mon 23-09-19 13:34:18, David Hildenbrand wrote:
> >> On 23.09.19 13:15, Michal Hocko wrote:
> > [...]
> >>> I am wondering why those pages get onlined when they are, in fact,
> >>> supposed to be offline.
> >>>
> >>
> >> It's the current way of emulating sub-memory-block hotplug on top of the
> >> memory bock device API we have. Hyper-V and XEN have been using that for
> >> a long time.
> > 
> > Do they really have to use the existing block interface when they in
> > fact do not operate on the block granularity? Zone device memory already
> > acts on sub section/block boundaries.
> > 
> 
> Yes, we need memory blocks, especially for user space to properly online
> them (as we discussed a while back, to decide on a zone) and for udev
> events, to e.g., properly reload kexec when memory blocks get
> added/removed/onlined/offlined.

Just to make sure I really follow. We need a user interface to control
where the memory gets onlined but it is the driver which determines
which part of the block really gets onlined, right?
-- 
Michal Hocko
SUSE Labs