Messages in this thread | | | Subject | Re: [PATCH v2 1/2] mm/page_alloc: use ac->high_zoneidx for classzone_idx | From | Vlastimil Babka <> | Date | Thu, 19 Mar 2020 13:29:19 +0100 |
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On 3/18/20 4:32 AM, js1304@gmail.com wrote: > From: Joonsoo Kim <iamjoonsoo.kim@lge.com> > > Currently, we use the zone index of preferred_zone which represents > the best matching zone for allocation, as classzone_idx. It has a problem > on NUMA system with ZONE_MOVABLE. > > In NUMA system, it can be possible that each node has different populated > zones. For example, node 0 could have DMA/DMA32/NORMAL/MOVABLE zone and > node 1 could have only NORMAL zone. In this setup, allocation request > initiated on node 0 and the one on node 1 would have different > classzone_idx, 3 and 2, respectively, since their preferred_zones are > different. If they are handled by only their own node, there is no problem. > However, if they are somtimes handled by the remote node due to memory > shortage, the problem would happen. > > In the following setup, allocation initiated on node 1 will have some > precedence than allocation initiated on node 0 when former allocation is > processed on node 0 due to not enough memory on node 1. They will have > different lowmem reserve due to their different classzone_idx thus > an watermark bars are also different.
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> Reported-by: Ye Xiaolong <xiaolong.ye@intel.com> > Tested-by: Ye Xiaolong <xiaolong.ye@intel.com> > Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@lge.com>
With the clarifications that David requested,
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Thanks!
> --- > mm/internal.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/mm/internal.h b/mm/internal.h > index c39c895..aebaa33 100644 > --- a/mm/internal.h > +++ b/mm/internal.h > @@ -119,7 +119,7 @@ struct alloc_context { > bool spread_dirty_pages; > }; > > -#define ac_classzone_idx(ac) zonelist_zone_idx(ac->preferred_zoneref) > +#define ac_classzone_idx(ac) (ac->high_zoneidx) > > /* > * Locate the struct page for both the matching buddy in our >
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