linux-kernel - [PATCH] mm: memcontrol: skip propagate percpu vmstat values to current memcg

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Message-Id: <20210119052744.96765-1-songmuchun@bytedance.com>
Date:   Tue, 19 Jan 2021 13:27:44 +0800
From:   Muchun Song <songmuchun@...edance.com>
To:     hannes@...xchg.org, mhocko@...nel.org, vdavydov.dev@...il.com,
        akpm@...ux-foundation.org
Cc:     cgroups@...r.kernel.org, linux-mm@...ck.org,
        linux-kernel@...r.kernel.org,
        Muchun Song <songmuchun@...edance.com>
Subject: [PATCH] mm: memcontrol: skip propagate percpu vmstat values to current memcg

The current memcg will be freed soon, so updating it's vmstat and
vmevent values is pointless. Just skip updating it.

Signed-off-by: Muchun Song <songmuchun@...edance.com>
---
 mm/memcontrol.c | 7 ++++---
 1 file changed, 4 insertions(+), 3 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index c0a90767e264..597fbe9acf93 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -3700,7 +3700,7 @@ static void memcg_flush_percpu_vmstats(struct mem_cgroup *memcg)
 		for (i = 0; i < MEMCG_NR_STAT; i++)
 			stat[i] += per_cpu(memcg->vmstats_percpu->stat[i], cpu);
 
-	for (mi = memcg; mi; mi = parent_mem_cgroup(mi))
+	for (mi = parent_mem_cgroup(memcg); mi; mi = parent_mem_cgroup(mi))
 		for (i = 0; i < MEMCG_NR_STAT; i++)
 			atomic_long_add(stat[i], &mi->vmstats[i]);
 
@@ -3716,7 +3716,8 @@ static void memcg_flush_percpu_vmstats(struct mem_cgroup *memcg)
 				stat[i] += per_cpu(
 					pn->lruvec_stat_cpu->count[i], cpu);
 
-		for (pi = pn; pi; pi = parent_nodeinfo(pi, node))
+		for (pi = parent_nodeinfo(pn, node); pi;
+		     pi = parent_nodeinfo(pi, node))
 			for (i = 0; i < NR_VM_NODE_STAT_ITEMS; i++)
 				atomic_long_add(stat[i], &pi->lruvec_stat[i]);
 	}
@@ -3736,7 +3737,7 @@ static void memcg_flush_percpu_vmevents(struct mem_cgroup *memcg)
 			events[i] += per_cpu(memcg->vmstats_percpu->events[i],
 					     cpu);
 
-	for (mi = memcg; mi; mi = parent_mem_cgroup(mi))
+	for (mi = parent_mem_cgroup(memcg); mi; mi = parent_mem_cgroup(mi))
 		for (i = 0; i < NR_VM_EVENT_ITEMS; i++)
 			atomic_long_add(events[i], &mi->vmevents[i]);
 }
-- 
2.11.0