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From:   Muchun Song <songmuchun@bytedance.com>
Date:   Sun, 22 May 2022 14:47:42 +0800
Message-ID: <CAMZfGtX1pste5vY_RE3N5LQ1_+BUjyRbSUa1yf0v7vboJj_iOg@mail.gmail.com>
Subject: Re: [PATCH mm v2 7/9] memcg: enable accounting for large allocations
 in mem_cgroup_css_alloc
To:     Vasily Averin <vvs@openvz.org>
Cc:     Andrew Morton <akpm@linux-foundation.org>, kernel@openvz.org,
        LKML <linux-kernel@vger.kernel.org>,
        Linux Memory Management List <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>,
        Cgroups <cgroups@vger.kernel.org>
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On Sun, May 22, 2022 at 12:38 AM Vasily Averin <vvs@openvz.org> wrote:
>
> 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: Muchun Song <songmuchun@bytedance.com>