Re: [PATCH v2 5/5] mm, memory_hotplug: Refactor shrink_zone/pgdat_span

[Michal Hocko <mhocko@kernel.org>]

On Tue 27-11-18 17:20:05, Oscar Salvador wrote:
> From: Oscar Salvador <osalvador@suse.com>
> 
> shrink_zone_span and shrink_pgdat_span look a bit weird.
> 
> They both have a loop at the end to check if the zone
> or pgdat contains only holes in case the section to be removed
> was not either the first one or the last one.
> 
> Both code loops look quite similar, so we can simplify it a bit.
> We do that by creating a function (has_only_holes), that basically
> calls find_smallest_section_pfn() with the full range.
> In case nothing has to be found, we do not have any more sections
> there.
> 
> To be honest, I am not really sure we even need to go through this
> check in case we are removing a middle section, because from what I can see,
> we will always have a first/last section.
> 
> Taking the chance, we could also simplify both find_smallest_section_pfn()
> and find_biggest_section_pfn() functions and move the common code
> to a helper.

I didn't get to read through this whole series but one thing that is on
my todo list for a long time is to remove all this stuff. I do not think
we really want to simplify it when there shouldn't be any real reason to
have it around at all. Why do we need to shrink zone/node at all?

Now that we can override and assign memory to both normal na movable
zones I think we should be good to remove shrinking.

-- 
Michal Hocko
SUSE Labs