Re: [PATCH 2/2] mm, memory_hotplug: remove zone restrictions

[Michal Hocko]

On Fri 30-06-17 17:39:56, Wei Yang wrote:
> On Fri, Jun 30, 2017 at 4:39 PM, Michal Hocko <mhocko@xxxxxxxxxx> wrote:
[...]
> > yes and to be honest I do not plan to fix it unless somebody has a real
> > life usecase for it. Now that we allow explicit onlininig type anywhere
> > it seems like a reasonable behavior and this will allow us to remove
> > quite some code which is always a good deal wrt longterm maintenance.
> >
> 
> hmm... the statistics displayed in /proc/zoneinfo would be meaningless
> for zone_normal and zone_movable.

Why would they be meaningless? Counters will always reflect the actual
use - if not then it is a bug. And wrt to zone description what is
meaningless about
memory34/valid_zones:Normal
memory35/valid_zones:Normal Movable
memory36/valid_zones:Movable
memory37/valid_zones:Movable Normal
memory38/valid_zones:Movable Normal
memory39/valid_zones:Movable Normal
memory40/valid_zones:Normal
memory41/valid_zones:Movable

And
Node 1, zone   Normal
  pages free     65465
        min      156
        low      221
        high     286
        spanned  229376
        present  65536
        managed  65536
[...]
  start_pfn:           1114112
Node 1, zone  Movable
  pages free     65443
        min      156
        low      221
        high     286
        spanned  196608
        present  65536
        managed  65536
[...]
  start_pfn:           1179648

ranges are clearly defined as [start_pfn, start_pfn+managed] and managed
matches the number of onlined pages (256MB).
-- 
Michal Hocko
SUSE Labs