From: "T.J. Mercier" tjmercier@google.com

mainline inclusion from mainline-v6.9-rc1 commit 13ef7424577ff9b663aeaa4fda67e186d9856df3 category: bugfix bugzilla: https://gitee.com/openeuler/kernel/issues/IB0CT3

Reference: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/commit/?id=...

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The root memcg is onlined even when memcg is disabled. When it's onlined a 2 second periodic stat flush is started, but no stat flushing is required when memcg is disabled because there can be no child memcgs. Most calls to flush memcg stats are avoided when memcg is disabled as a result of the mem_cgroup_disabled check added in 7d7ef0a4686a ("mm: memcg: restore subtree stats flushing"), but the periodic flushing started in mem_cgroup_css_online is not. Skip it.

Link: https://lkml.kernel.org/r/20240126211927.1171338-1-tjmercier@google.com Fixes: aa48e47e3906 ("memcg: infrastructure to flush memcg stats") Signed-off-by: T.J. Mercier tjmercier@google.com Acked-by: Shakeel Butt shakeelb@google.com Acked-by: Johannes Weiner hannes@cmpxchg.org Acked-by: Chris Li chrisl@kernel.org Reported-by: Minchan Kim minchan@google.com Reviewed-by: Yosry Ahmed yosryahmed@google.com Cc: Michal Hocko mhocko@kernel.org Cc: Muchun Song muchun.song@linux.dev Cc: Roman Gushchin roman.gushchin@linux.dev Cc: Michal Koutn mkoutny@suse.com Signed-off-by: Andrew Morton akpm@linux-foundation.org

Conflicts: mm/memcontrol.c [context can not be matched] Signed-off-by: Chen Ridong chenridong@huawei.com --- mm/memcontrol.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c index aefaa33147b1..3e928581ab47 100644 --- a/mm/memcontrol.c +++ b/mm/memcontrol.c @@ -6581,7 +6581,7 @@ static int mem_cgroup_css_online(struct cgroup_subsys_state *css) refcount_set(&memcg->id.ref, 1); css_get(css);

- if (unlikely(mem_cgroup_is_root(memcg))) + if (unlikely(mem_cgroup_is_root(memcg)) && !mem_cgroup_disabled()) queue_delayed_work(system_unbound_wq, &stats_flush_dwork, 2UL*HZ); return 0;