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From:   Shakeel Butt <shakeelb@google.com>
Date:   Thu, 19 May 2022 18:31:50 -0700
Message-ID: <CALvZod5pFkm36r1nT2vmUX+Q1hy-MTKaGXOXpcT0Wra1oU=etw@mail.gmail.com>
Subject: Re: [PATCH 3/4] memcg: enable accounting for struct cgroup
To:     Vasily Averin <vvs@openvz.org>
Cc:     Roman Gushchin <roman.gushchin@linux.dev>,
        =?UTF-8?Q?Michal_Koutn=C3=BD?= <mkoutny@suse.com>,
        kernel@openvz.org, LKML <linux-kernel@vger.kernel.org>,
        Vlastimil Babka <vbabka@suse.cz>,
        Michal Hocko <mhocko@suse.com>,
        Cgroups <cgroups@vger.kernel.org>
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On Fri, May 13, 2022 at 8:52 AM Vasily Averin <vvs@openvz.org> wrote:
>
> Creating each new cgroup allocates 4Kb for struct cgroup. This is the
> largest memory allocation in this scenario and is epecially important
> for small VMs with 1-2 CPUs.
>
> Accounting of this memory helps to avoid misuse inside memcg-limited
> containers.
>
> Signed-off-by: Vasily Averin <vvs@openvz.org>
> ---
>  kernel/cgroup/cgroup.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
> index adb820e98f24..7595127c5b3a 100644
> --- a/kernel/cgroup/cgroup.c
> +++ b/kernel/cgroup/cgroup.c
> @@ -5353,7 +5353,7 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
>
>         /* allocate the cgroup and its ID, 0 is reserved for the root */
>         cgrp = kzalloc(struct_size(cgrp, ancestor_ids, (level + 1)),
> -                      GFP_KERNEL);
> +                      GFP_KERNEL_ACCOUNT);
>         if (!cgrp)
>                 return ERR_PTR(-ENOMEM);
>

Please include cgroup_rstat_cpu as well.