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Date:   Mon, 13 Jun 2022 08:35:26 +0300
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From:   Vasily Averin <vvs@openvz.org>
Subject: [PATCH mm v4 6/9] memcg: enable accounting for percpu allocation of
 struct cgroup_rstat_cpu
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: <3e1d6eab-57c7-ba3d-67e1-c45aa0dfa2ab@openvz.org>
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Precedence: bulk

struct cgroup_rstat_cpu is percpu allocated for each new cgroup and
can consume a significant portion of all allocated memory on nodes
with a large number of CPUs.

Common part of the cgroup creation:
Allocs  Alloc   $1*$2   Sum	Allocation
number  size
--------------------------------------------
16  ~   352     5632    5632    KERNFS
1   +   4096    4096    9728    (cgroup_mkdir+0xe4)
1       584     584     10312   (radix_tree_node_alloc.constprop.0+0x89)
1       192     192     10504   (__d_alloc+0x29)
2       72      144     10648   (avc_alloc_node+0x27)
2       64      128     10776   (percpu_ref_init+0x6a)
1       64      64      10840   (memcg_list_lru_alloc+0x21a)
percpu:
1   +   192     192     192     call_site=psi_cgroup_alloc+0x1e
1   +   96      96      288     call_site=cgroup_rstat_init+0x5f
2       12      24      312     call_site=percpu_ref_init+0x23
1       6       6       318     call_site=__percpu_counter_init+0x22

 '+' -- to be accounted,
 '~' -- partially accounted

Signed-off-by: Vasily Averin <vvs@openvz.org>
Acked-by: Shakeel Butt <shakeelb@google.com>
Acked-by: Roman Gushchin <roman.gushchin@linux.dev>
Acked-by: Muchun Song <songmuchun@bytedance.com>
---
 kernel/cgroup/rstat.c | 3 ++-
 1 file changed, 2 insertions(+), 1 deletion(-)

diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index 24b5c2ab5598..2904b185b01b 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -257,7 +257,8 @@ int cgroup_rstat_init(struct cgroup *cgrp)
 
 	/* the root cgrp has rstat_cpu preallocated */
 	if (!cgrp->rstat_cpu) {
-		cgrp->rstat_cpu = alloc_percpu(struct cgroup_rstat_cpu);
+		cgrp->rstat_cpu = alloc_percpu_gfp(struct cgroup_rstat_cpu,
+						   GFP_KERNEL_ACCOUNT);
 		if (!cgrp->rstat_cpu)
 			return -ENOMEM;
 	}
-- 
2.36.1