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Date:   Mon, 30 May 2022 14:26:50 +0300
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From:   Vasily Averin <vvs@openvz.org>
Subject: [PATCH mm v3 7/9] memcg: enable accounting for large allocations in
 mem_cgroup_css_alloc
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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Precedence: bulk

Creation of each memory cgroup allocates few huge objects in
mem_cgroup_css_alloc(). Its size exceeds the size of memory
accounted in common part of cgroup creation:

common part: 	~11Kb	+  318 bytes percpu
memcg: 		~17Kb	+ 4692 bytes percpu

memory:
------
Allocs  Alloc   $1*$2   Sum     Allocation
number  size
--------------------------------------------
1   +   8192    8192    8192    (mem_cgroup_css_alloc+0x4a) <NB
14  ~   352     4928    13120   KERNFS
1   +   2048    2048    15168   (mem_cgroup_css_alloc+0xdd) <NB
1       1024    1024    16192   (alloc_shrinker_info+0x79)
1       584     584     16776   (radix_tree_node_alloc.constprop.0+0x89)
2       64      128     16904   (percpu_ref_init+0x6a)
1       64      64      16968   (mem_cgroup_css_online+0x32)

1   =   3684    3684    3684    call_site=mem_cgroup_css_alloc+0x9e
1   =   984     984     4668    call_site=mem_cgroup_css_alloc+0xfd
2       12      24      4692    call_site=percpu_ref_init+0x23

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

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

Signed-off-by: Vasily Averin <vvs@openvz.org>
Reviewed-by: Roman Gushchin <roman.gushchin@linux.dev>
Reviewed-by: Michal Koutný <mkoutny@suse.com>
Acked-by: Shakeel Butt <shakeelb@google.com>
Reviewed-by: Muchun Song <songmuchun@bytedance.com>
---
 mm/memcontrol.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/memcontrol.c b/mm/memcontrol.c
index abec50f31fe6..376734af8935 100644
--- a/mm/memcontrol.c
+++ b/mm/memcontrol.c
@@ -5064,7 +5064,7 @@ static int alloc_mem_cgroup_per_node_info(struct mem_cgroup *memcg, int node)
 {
 	struct mem_cgroup_per_node *pn;
 
-	pn = kzalloc_node(sizeof(*pn), GFP_KERNEL, node);
+	pn = kzalloc_node(sizeof(*pn), GFP_KERNEL_ACCOUNT, node);
 	if (!pn)
 		return 1;
 
@@ -5116,7 +5116,7 @@ static struct mem_cgroup *mem_cgroup_alloc(void)
 	int __maybe_unused i;
 	long error = -ENOMEM;
 
-	memcg = kzalloc(struct_size(memcg, nodeinfo, nr_node_ids), GFP_KERNEL);
+	memcg = kzalloc(struct_size(memcg, nodeinfo, nr_node_ids), GFP_KERNEL_ACCOUNT);
 	if (!memcg)
 		return ERR_PTR(error);
 
-- 
2.36.1