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Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for ZONE_MOVABLE request

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On Fri 25-08-17 09:15:43, Joonsoo Kim wrote:
> On Thu, Aug 24, 2017 at 11:30:50AM +0200, Michal Hocko wrote:
> > On Thu 24-08-17 14:45:46, Joonsoo Kim wrote:
> > > From: Joonsoo Kim <iamjoonsoo.kim@lge.com>
> > > 
> > > Freepage on ZONE_HIGHMEM doesn't work for kernel memory so it's not that
> > > important to reserve. When ZONE_MOVABLE is used, this problem would
> > > theorectically cause to decrease usable memory for GFP_HIGHUSER_MOVABLE
> > > allocation request which is mainly used for page cache and anon page
> > > allocation. So, fix it.
> > 
> > I do not really understand what is the problem you are trying to fix.
> > Yes the memory is reserved for a higher priority consumer and that is
> > deliberate AFAICT. Just consider that an OOM victim wants to make
> > further progress and rely on memory reserve while doing
> > GFP_HIGHUSER_MOVABLE request.
> > 
> > So what is the real problem you are trying to address here?
> 
> If the system has the both, ZONE_HIGHMEM and ZONE_MOVABLE,
> ZONE_HIGHMEM will reserve the memory for ZONE_MOVABLE request.

Ohh, right. I forgot that __GFP_MOVABLE doesn't really enforce the
movable zone. It does so only if __GFP_HIGHMEM is specified as well when
ZONE_HIGHMEM is enabled. So indeed reserving memory in both is somehow
awkward. So why don't we simply remove reserves from the movable zone
when the highmem zone is enabled?
-- 
Michal Hocko
SUSE Labs

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[PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for ZONE_MOVABLE request js1304@gmail.com - 2017-08-24 07:50 +0200
  Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Michal Hocko <mhocko@kernel.org> - 2017-08-24 11:40 +0200
    Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2017-08-25 02:20 +0200
      Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Michal Hocko <mhocko@kernel.org> - 2017-08-25 09:40 +0200
  Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Vlastimil Babka <vbabka@suse.cz> - 2017-08-24 11:50 +0200
    Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2017-08-25 02:30 +0200
      Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Michal Hocko <mhocko@kernel.org> - 2017-08-25 09:40 +0200
        Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2017-08-28 02:20 +0200
          Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Michal Hocko <mhocko@kernel.org> - 2017-08-28 12:00 +0200
            Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2017-08-29 02:50 +0200
              Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Michal Hocko <mhocko@kernel.org> - 2017-08-29 15:40 +0200
                Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2017-08-31 03:50 +0200
      Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Vlastimil Babka <vbabka@suse.cz> - 2017-08-25 10:00 +0200
        Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2017-08-28 02:30 +0200
          Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Vlastimil Babka <vbabka@suse.cz> - 2017-08-28 08:50 +0200
            Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Joonsoo Kim <iamjoonsoo.kim@lge.com> - 2017-08-29 02:40 +0200
              Re: [PATCH] mm/page_alloc: don't reserve ZONE_HIGHMEM for  ZONE_MOVABLE request Vlastimil Babka <vbabka@suse.cz> - 2017-08-29 09:10 +0200

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