From a9320aae68a1cd3f41b9846e24504b09ffc3311e Mon Sep 17 00:00:00 2001 From: Wei Yang Date: Thu, 28 Apr 2022 23:15:59 -0700 Subject: [PATCH] mm/memcg: move generation assignment and comparison together For each round-trip, we assign generation on first invocation and compare it on subsequent invocations. Let's move them together to make it more self-explaining. Also this reduce a check on prev. [hannes@cmpxchg.org: better comment to explain reclaim model] Link: https://lkml.kernel.org/r/20220330234719.18340-4-richard.weiyang@gmail.com Signed-off-by: Wei Yang Acked-by: Johannes Weiner Reviewed-by: Roman Gushchin Signed-off-by: Andrew Morton --- mm/memcontrol.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/mm/memcontrol.c b/mm/memcontrol.c index 1b76d56..1ae0a2a 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -1021,7 +1021,13 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, mz = root->nodeinfo[reclaim->pgdat->node_id]; iter = &mz->iter; - if (prev && reclaim->generation != iter->generation) + /* + * On start, join the current reclaim iteration cycle. + * Exit when a concurrent walker completes it. + */ + if (!prev) + reclaim->generation = iter->generation; + else if (reclaim->generation != iter->generation) goto out_unlock; while (1) { @@ -1083,8 +1089,6 @@ struct mem_cgroup *mem_cgroup_iter(struct mem_cgroup *root, if (!memcg) iter->generation++; - else if (!prev) - reclaim->generation = iter->generation; } out_unlock: -- 2.7.4