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From:   Wei Yang <richardw.yang@linux.intel.com>
To:     akpm@linux-foundation.org
Cc:     linux-mm@kvack.org, linux-kernel@vger.kernel.org, mhocko@suse.com,
        yang.shi@linux.alibaba.com, rientjes@google.com, david@redhat.com,
        Wei Yang <richardw.yang@linux.intel.com>
Subject: [Patch v4 3/4] mm/migrate.c: check pagelist in move_pages_and_store_status()
Date:   Thu, 30 Jan 2020 06:16:15 +0800
Message-Id: <20200129221616.25432-4-richardw.yang@linux.intel.com>
In-Reply-To: <20200129221616.25432-1-richardw.yang@linux.intel.com>
References: <20200129221616.25432-1-richardw.yang@linux.intel.com>
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

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@linux.intel.com>
Acked-by: Michal Hocko <mhocko@suse.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
---
 mm/migrate.c | 9 +++------
 1 file changed, 3 insertions(+), 6 deletions(-)

diff --git a/mm/migrate.c b/mm/migrate.c
index 92e8c9396368..981916007b4f 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;
@@ -1675,9 +1675,6 @@ 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