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Date:   Thu, 29 Jul 2021 14:52:31 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Miaohe Lin <linmiaohe@huawei.com>
Cc:     hannes@cmpxchg.org, mhocko@kernel.org, vdavydov.dev@gmail.com,
        akpm@linux-foundation.org, shakeelb@google.com, guro@fb.com,
        alexs@kernel.org, richard.weiyang@gmail.com,
        songmuchun@bytedance.com, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, cgroups@vger.kernel.org
Subject: Re: [PATCH 4/5] mm, memcg: avoid possible NULL pointer dereferencing
 in mem_cgroup_init()
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References: <20210729125755.16871-1-linmiaohe@huawei.com>
 <20210729125755.16871-5-linmiaohe@huawei.com>
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On Thu, Jul 29, 2021 at 08:57:54PM +0800, Miaohe Lin wrote:
> rtpn might be NULL in very rare case. We have better to check it before
> dereferencing it. Since memcg can live with NULL rb_tree_per_node in
> soft_limit_tree, warn this case and continue.

Why would we need to warn?  the GFP flags don't contain NOWARN, so
we already know an allocation failed.