On Thu, Apr 05, 2018 at 09:57:53AM +0200, Michal Hocko wrote:
> On Thu 05-04-18 16:27:16, Joonsoo Kim wrote:
> > From: Joonsoo Kim <iamjoonsoo....@lge.com>
> > 
> > ZONE_MOVABLE only has movable pages so we don't need to keep enough
> > freepages to avoid or deal with fragmentation. So, don't count it.
> > 
> > This changes min_free_kbytes and thus min_watermark greatly
> > if ZONE_MOVABLE is used. It will make the user uses more memory.
> 
> OK, but why does it matter. Has anybody seen this as an issue?

There was a regression report for CMA patchset and I think that it is
related to this problem. CMA patchset makes the system uses one more
zone (ZONE_MOVABLE) and then increase min_free_kbytes. It reduces
usable memory and it could cause regression.

http://lkml.kernel.org/r/20180102063528.GG30397@yexl-desktop

Thanks.

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