[PATCH 7/8] mm/migrate.c: move page on next iteration

[Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>]

When page is not successfully queued for migration, we would move pages
on pagelist immediately. Actually, this could be done in the next
iteration by telling it we need some help.

This patch adds a new variable need_move to be an indication. After
this, we only need to call move_pages_and_store_status() twice.

Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
---
 mm/migrate.c | 18 +++++++++---------
 1 file changed, 9 insertions(+), 9 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index aee5aeb082c4..2a857fec65b6 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1610,6 +1610,7 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 	LIST_HEAD(pagelist);
 	int start, i;
 	int err = 0, err1;
+	int need_move = 0;
 
 	migrate_prep();
 
@@ -1641,13 +1642,15 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 		if (current_node == NUMA_NO_NODE) {
 			current_node = node;
 			start = i;
-		} else if (node != current_node) {
+		} else if (node != current_node || need_move) {
 			err = move_pages_and_store_status(mm, current_node,
-					&pagelist, status, start, i - start);
+					&pagelist, status, start,
+					i - start - need_move);
 			if (err)
 				goto out;
 			start = i;
 			current_node = node;
+			need_move = 0;
 		}
 
 		/*
@@ -1662,6 +1665,9 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 			continue;
 		}
 
+		/* Ask next iteration to move us */
+		need_move = 1;
+
 		/*
 		 * Two possible cases for err here:
 		 * == 0: page is already on the target node, then store
@@ -1671,17 +1677,11 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 		err = store_status(status, i, err ? : current_node, 1);
 		if (err)
 			goto out_flush;
-
-		err = move_pages_and_store_status(mm, current_node, &pagelist,
-				status, start, i - start);
-		if (err)
-			goto out;
-		current_node = NUMA_NO_NODE;
 	}
 out_flush:
 	/* Make sure we do not overwrite the existing error */
 	err1 = move_pages_and_store_status(mm, current_node, &pagelist,
-				status, start, i - start);
+				status, start, i - start - need_move);
 	if (err >= 0)
 		err = err1;
 out:
-- 
2.17.1