linux-kernel - [Patch v2 3/4] mm/migrate.c: check pagelist in move_pages_and_store

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Date:   Wed, 22 Jan 2020 09:16:46 +0800
From:   Wei Yang <richardw.yang@...ux.intel.com>
To:     akpm@...ux-foundation.org
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org, mhocko@...e.com,
        yang.shi@...ux.alibaba.com, rientjes@...gle.com,
        Wei Yang <richardw.yang@...ux.intel.com>
Subject: [Patch v2 3/4] mm/migrate.c: check pagelist in move_pages_and_store_status()

When pagelist is empty, it is not necessary to do the move and store.
Also it consolidate the empty list check in one place.

Signed-off-by: Wei Yang <richardw.yang@...ux.intel.com>
Acked-by: Michal Hocko <mhocko@...e.com>
---
 mm/migrate.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index a4d3bd6475e1..80d2bba57265 100644
--- a/mm/migrate.c
+++ b/mm/migrate.c
@@ -1499,9 +1499,6 @@ static int do_move_pages_to_node(struct mm_struct *mm,
 {
 	int err;
 
-	if (list_empty(pagelist))
-		return 0;
-
 	err = migrate_pages(pagelist, alloc_new_node_page, NULL, node,
 			MIGRATE_SYNC, MR_SYSCALL);
 	if (err)
@@ -1589,6 +1586,9 @@ static int move_pages_and_store_status(struct mm_struct *mm, int node,
 {
 	int err;
 
+	if (list_empty(pagelist))
+		return 0;
+
 	err = do_move_pages_to_node(mm, pagelist, node);
 	if (err)
 		return err;
@@ -1676,9 +1676,6 @@ static int do_pages_move(struct mm_struct *mm, nodemask_t task_nodes,
 		current_node = NUMA_NO_NODE;
 	}
 out_flush:
-	if (list_empty(&pagelist))
-		return err;
-
 	/* Make sure we do not overwrite the existing error */
 	err1 = move_pages_and_store_status(mm, current_node, &pagelist,
 				status, start, i - start);
-- 
2.17.1