On Wed, Jul 06, 2016 at 09:58:50AM +0100, Mel Gorman wrote: > On Wed, Jul 06, 2016 at 09:02:52AM +0900, Minchan Kim wrote: > > On Fri, Jul 01, 2016 at 09:01:39PM +0100, Mel Gorman wrote: > > > The number of LRU pages, dirty pages and writeback pages must be accounted > > > for on both zones and nodes because of the reclaim retry logic, compaction > > > retry logic and highmem calculations all depending on per-zone stats. > > > > > > The retry logic is only critical for allocations that can use any zones. > > > > Sorry, I cannot follow this assertion. > > Could you explain? > > > > The patch has been reworked since and I tried clarifying the changelog. > Does this help? > It occurred to me at breakfast that this should be more consistent with the OOM killer on both 32-bit and 64-bit so; diff --git a/mm/compaction.c b/mm/compaction.c index dfe7dafe8e8b..640532831b94 100644 --- a/mm/compaction.c +++ b/mm/compaction.c @@ -1448,11 +1448,9 @@ bool compaction_zonelist_suitable(struct alloc_context *ac, int order, struct zoneref *z; pg_data_t *last_pgdat = NULL; -#ifdef CONFIG_HIGHMEM /* Do not retry compaction for zone-constrained allocations */ - if (!is_highmem_idx(ac->high_zoneidx)) + if (ac->high_zoneidx < ZONE_NORMAL) return false; -#endif /* * Make sure at least one zone would pass __compaction_suitable if we continue diff --git a/mm/page_alloc.c b/mm/page_alloc.c index ded48e580abc..194a8162528b 100644 --- a/mm/page_alloc.c +++ b/mm/page_alloc.c @@ -3455,11 +3455,11 @@ should_reclaim_retry(gfp_t gfp_mask, unsigned order, return false; /* - * Blindly retry allocation requests that cannot use all zones. We do - * not have a reliable and fast means of calculating reclaimable, dirty - * and writeback pages in eligible zones. + * Blindly retry lowmem allocation requests that are often ignored by + * the OOM killer as we not have a reliable and fast means of + * calculating reclaimable, dirty and writeback pages in eligible zones. */ - if (IS_ENABLED(CONFIG_HIGHMEM) && !is_highmem_idx(gfp_zone(gfp_mask))) + if (ac->high_zoneidx < ZONE_NORMAL) goto out; /* -- 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>