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Date:   Wed, 1 Jun 2022 19:34:34 +0200
From:   Michal =?iso-8859-1?Q?Koutn=FD?= <mkoutny@suse.com>
To:     Muchun Song <songmuchun@bytedance.com>
Cc:     hannes@cmpxchg.org, mhocko@kernel.org, roman.gushchin@linux.dev,
        shakeelb@google.com, akpm@linux-foundation.org,
        cgroups@vger.kernel.org, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, duanxiongchun@bytedance.com,
        longman@redhat.com
Subject: Re: [PATCH v5 03/11] mm: memcontrol: prepare objcg API for non-kmem
 usage
Message-ID: <20220601173434.GB16134@blackbody.suse.cz>
References: <20220530074919.46352-1-songmuchun@bytedance.com>
 <20220530074919.46352-4-songmuchun@bytedance.com>
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Hello.

On Mon, May 30, 2022 at 03:49:11PM +0800, Muchun Song <songmuchun@bytedance.com> wrote:
> So we also allocate an object cgroup for the root_mem_cgroup.

This change made me wary that this patch also kmem charging in the
root_mem_cgroup. Fortunately, get_obj_cgroup_from_current won't return
this objcg so all is fine.

> +}
> +#else
> +static inline void obj_cgroup_release_bytes(struct obj_cgroup *objcg)
> +{
> +}
> +#endif

This empty body is for !CONFIG_MEMCG_KMEM, however, the subsequent use for LRU
pages makes no use of these, so it's warranted.

Altogether, I find this correct, hence
Reviewed-by: Michal Koutn? <mkoutny@suse.com>