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@xxxxxxx> > > > > > > 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 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>
