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Message-ID: <a1fcdab2-a208-0fad-3f4e-233317ab828f@openvz.org>
Date:   Mon, 30 May 2022 14:27:07 +0300
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From:   Vasily Averin <vvs@openvz.org>
Subject: [PATCH mm v3 9/9] memcg: enable accounting for perpu allocation of
 struct rt_rq
To:     Andrew Morton <akpm@linux-foundation.org>
Cc:     kernel@openvz.org, linux-kernel@vger.kernel.org,
        linux-mm@kvack.org, Shakeel Butt <shakeelb@google.com>,
        Roman Gushchin <roman.gushchin@linux.dev>,
        =?UTF-8?Q?Michal_Koutn=c3=bd?= <mkoutny@suse.com>,
        Vlastimil Babka <vbabka@suse.cz>,
        Michal Hocko <mhocko@suse.com>,
        Muchun Song <songmuchun@bytedance.com>, cgroups@vger.kernel.org
References: <06505918-3b8a-0ad5-5951-89ecb510138e@openvz.org>
 <cover.1653899364.git.vvs@openvz.org>
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If enabled in config, alloc_rt_sched_group() is called for each new
cpu cgroup and allocates a huge (~1700 bytes) percpu struct rt_rq.
This significantly exceeds the size of the percpu allocation in the
common part of cgroup creation.

Memory allocated during new cpu cgroup creation
(with enabled RT_GROUP_SCHED):
common part:    ~11Kb   +   318 bytes percpu
cpu cgroup:     ~2.5Kb  + ~2800 bytes percpu

Accounting for this memory helps to avoid misuse inside memcg-limited
containers.

Signed-off-by: Vasily Averin <vvs@openvz.org>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
---
 kernel/sched/rt.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/sched/rt.c b/kernel/sched/rt.c
index 8c9ed9664840..44a8fc096e33 100644
--- a/kernel/sched/rt.c
+++ b/kernel/sched/rt.c
@@ -256,7 +256,7 @@ int alloc_rt_sched_group(struct task_group *tg, struct task_group *parent)
 
 	for_each_possible_cpu(i) {
 		rt_rq = kzalloc_node(sizeof(struct rt_rq),
-				     GFP_KERNEL, cpu_to_node(i));
+				     GFP_KERNEL_ACCOUNT, cpu_to_node(i));
 		if (!rt_rq)
 			goto err;
 
-- 
2.36.1