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

[Joonsoo Kim]

On Fri, Aug 25, 2017 at 09:56:10AM +0200, Vlastimil Babka wrote:
> On 08/25/2017 02:20 AM, Joonsoo Kim wrote:
> > On Thu, Aug 24, 2017 at 11:41:58AM +0200, Vlastimil Babka wrote:
> > 
> > Hmm, this is already pointed by Minchan and I have answered that.
> > 
> > lkml.kernel.org/r/<20170421013243.GA13966@js1304-desktop>
> > 
> > If you have a better idea, please let me know.
> 
> My idea is that size of sysctl_lowmem_reserve_ratio is ZONE_NORMAL+1 and
> it has no entries for zones > NORMAL. The
> setup_per_zone_lowmem_reserve() is adjusted to only set
> lower_zone->lowmem_reserve[j] for idx <= ZONE_NORMAL.
> 
> I can't imagine somebody would want override the ratio for HIGHMEM or
> MOVABLE
> (where it has no effect anyway) so the simplest thing is not to expose
> it at all.

Seems reasonable. However, if there is a user who checks
sysctl_lowmem_reserve_ratio entry for HIGHMEM and change it, suggested
interface will cause a problem since it doesn't expose ratio for
HIGHMEM. Am I missing something?

Thanks.


> 
> > Thanks.
> > 
> 
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