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Message-Id: <20201027080256.76497-5-songmuchun@bytedance.com>
Date: Tue, 27 Oct 2020 16:02:55 +0800
From: Muchun Song <songmuchun@...edance.com>
To: hannes@...xchg.org, mhocko@...nel.org, vdavydov.dev@...il.com,
akpm@...ux-foundation.org, shakeelb@...gle.com, guro@...com,
iamjoonsoo.kim@....com, laoar.shao@...il.com, chris@...isdown.name,
christian.brauner@...ntu.com, peterz@...radead.org,
mingo@...nel.org, keescook@...omium.org, tglx@...utronix.de,
esyr@...hat.com, surenb@...gle.com, areber@...hat.com,
elver@...gle.com
Cc: linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
linux-mm@...ck.org, Muchun Song <songmuchun@...edance.com>
Subject: [PATCH 4/5] mm: memcg/slab: Fix root memcg vmstats
If we reparent the slab objects to the root memcg, when we free
the slab object, we need to update the per-memcg vmstats to keep
it correct for the root memcg. Now this at least affects the vmstat
of NR_KERNEL_STACK_KB for !CONFIG_VMAP_STACK when the thread stack
size is smaller than the PAGE_SIZE.
Fixes: ec9f02384f60 ("mm: workingset: fix vmstat counters for shadow nodes")
Signed-off-by: Muchun Song <songmuchun@...edance.com>
---
mm/memcontrol.c | 9 +++++++--
1 file changed, 7 insertions(+), 2 deletions(-)
diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index 22b4fb941b54..70345b15b150 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -875,8 +875,13 @@ void __mod_lruvec_kmem_state(void *p, enum node_stat_item idx, int val)
rcu_read_lock();
memcg = mem_cgroup_from_obj(p);
- /* Untracked pages have no memcg, no lruvec. Update only the node */
- if (!memcg || memcg == root_mem_cgroup) {
+ /*
+ * Untracked pages have no memcg, no lruvec. Update only the
+ * node. If we reparent the slab objects to the root memcg,
+ * when we free the slab object, we need to update the per-memcg
+ * vmstats to keep it correct for the root memcg.
+ */
+ if (!memcg) {
__mod_node_page_state(pgdat, idx, val);
} else {
lruvec = mem_cgroup_lruvec(memcg, pgdat);
--
2.20.1
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