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Date:   Thu, 18 Mar 2021 11:09:27 -0400
From:   Johannes Weiner <hannes@cmpxchg.org>
To:     Muchun Song <songmuchun@bytedance.com>
Cc:     guro@fb.com, mhocko@kernel.org, akpm@linux-foundation.org,
        shakeelb@google.com, vdavydov.dev@gmail.com,
        linux-kernel@vger.kernel.org, linux-mm@kvack.org,
        duanxiongchun@bytedance.com
Subject: Re: [PATCH v4 2/5] mm: memcontrol: directly access page->memcg_data
 in mm/page_alloc.c
Message-ID: <YFNtJzm2DNEVkTbO@cmpxchg.org>
References: <20210318110658.60892-1-songmuchun@bytedance.com>
 <20210318110658.60892-3-songmuchun@bytedance.com>
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On Thu, Mar 18, 2021 at 07:06:55PM +0800, Muchun Song 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>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>