[patch] mm, thp: abort compaction if migration page cannot be chargedto memcg

[David Rientjes]

If page migration cannot charge the new page to the memcg,
migrate_pages() will return -ENOMEM.  This isn't considered in memory
compaction however, and the loop continues to iterate over all pageblocks
trying in a futile attempt to continue migrations which are only bound to
fail.

This will short circuit and fail memory compaction if migrate_pages()
returns -ENOMEM.  COMPACT_PARTIAL is returned in case some migrations
were successful so that the page allocator will retry.

Signed-off-by: David Rientjes <rientjes@xxxxxxxxxx>
---
 mm/compaction.c |    5 ++++-
 1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/mm/compaction.c b/mm/compaction.c
--- a/mm/compaction.c
+++ b/mm/compaction.c
@@ -701,8 +701,11 @@ static int compact_zone(struct zone *zone, struct compact_control *cc)
 		if (err) {
 			putback_lru_pages(&cc->migratepages);
 			cc->nr_migratepages = 0;
+			if (err == -ENOMEM) {
+				ret = COMPACT_PARTIAL;
+				goto out;
+			}
 		}
-
 	}
 
 out:
--
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