From: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
new_page_nodemask is a migration callback and it tries to use a common
gfp flags for the target page allocation whether it is a base page or a
THP. The later only adds GFP_TRANSHUGE to the given mask. This results
in the allocation being slightly more aggressive than necessary because
the resulting gfp mask will contain also __GFP_RECLAIM_KSWAPD. THP
allocations usually exclude this flag to reduce over eager background
reclaim during a high THP allocation load which has been seen during
large mmaps initialization. There is no indication that this is a
problem for migration as well but theoretically the same might happen
when migrating large mappings to a different node. Make the migration
callback consistent with regular THP allocations.
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx>
---
mm/migrate.c | 5 +++++
1 file changed, 5 insertions(+)
diff --git a/mm/migrate.c b/mm/migrate.c
index 3b3d918..1cfc965 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1547,6 +1547,11 @@ struct page *new_page_nodemask(struct page *page,
}
if (PageTransHuge(page)) {
+ /*
+ * clear __GFP_RECALIM to make the migration callback
+ * consistent with regular THP allocations.
+ */
+ gfp_mask &= ~__GFP_RECLAIM;
gfp_mask |= GFP_TRANSHUGE;
order = HPAGE_PMD_ORDER;
}
--
2.7.4
