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References: <20210318110658.60892-1-songmuchun@bytedance.com> <20210318110658.60892-3-songmuchun@bytedance.com>
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From:   Shakeel Butt <shakeelb@google.com>
Date:   Thu, 18 Mar 2021 18:00:27 -0700
Message-ID: <CALvZod7m6ZDrmv6s5dJ=j1mj2ee2nqx5ZNZmr=giYL+C1rC26A@mail.gmail.com>
Subject: Re: [PATCH v4 2/5] mm: memcontrol: directly access page->memcg_data
 in mm/page_alloc.c
To:     Muchun Song <songmuchun@bytedance.com>
Cc:     Roman Gushchin <guro@fb.com>, Johannes Weiner <hannes@cmpxchg.org>,
        Michal Hocko <mhocko@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Vladimir Davydov <vdavydov.dev@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux MM <linux-mm@kvack.org>,
        Xiongchun duan <duanxiongchun@bytedance.com>
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On Thu, Mar 18, 2021 at 4:08 AM Muchun Song <songmuchun@bytedance.com> wrote:
>
> The page_memcg() is not suitable for use by page_expected_state() and
> page_bad_reason(). Because it can BUG_ON() for the slab pages when
> CONFIG_DEBUG_VM is enabled. As neither lru, nor kmem, nor slab page
> should have anything left in there by the time the page is freed, what
> we care about is whether the value of page->memcg_data is 0. So just
> directly access page->memcg_data here.
>
> Signed-off-by: Muchun Song <songmuchun@bytedance.com>

Reviewed-by: Shakeel Butt <shakeelb@google.com>