From: Wei Yang <richard.weiyang@gmail.com>
Date: Fri, 29 Apr 2022 06:15:58 +0000 (-0700)
Subject: mm/memcg: set pos explicitly for reclaim and !reclaim
X-Git-Url: http://git.maquefel.me/?a=commitdiff_plain;h=89d8330ccf2ad4c0744e1d1b77ffe2deb1641e54;p=linux.git

mm/memcg: set pos explicitly for reclaim and !reclaim

During mem_cgroup_iter, there are two ways to get iteration position:
reclaim vs non-reclaim mode.

Let's do it explicitly for reclaim vs non-reclaim mode.

Link: https://lkml.kernel.org/r/20220330234719.18340-3-richard.weiyang@gmail.com
Signed-off-by: Wei Yang <richard.weiyang@gmail.com>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index f06b5c249ecbd..1b76d5698900a 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -1013,9 +1013,6 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 	if (!root)
 		root = root_mem_cgroup;
 
-	if (prev && !reclaim)
-		pos = prev;
-
 	rcu_read_lock();
 
 	if (reclaim) {
@@ -1041,6 +1038,8 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root,
 			 */
 			(void)cmpxchg(&iter->position, pos, NULL);
 		}
+	} else if (prev) {
+		pos = prev;
 	}
 
 	if (pos)