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Subject: Re: [PATCH 4/5] mm, memcg: avoid possible NULL pointer dereferencing
 in mem_cgroup_init()
To:     Matthew Wilcox <willy@infradead.org>
CC:     <hannes@cmpxchg.org>, <mhocko@kernel.org>,
        <vdavydov.dev@gmail.com>, <akpm@linux-foundation.org>,
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        <richard.weiyang@gmail.com>, <songmuchun@bytedance.com>,
        <linux-mm@kvack.org>, <linux-kernel@vger.kernel.org>,
        <cgroups@vger.kernel.org>
References: <20210729125755.16871-1-linmiaohe@huawei.com>
 <20210729125755.16871-5-linmiaohe@huawei.com>
 <YQKyn8bKRblCDuND@casper.infradead.org>
From:   Miaohe Lin <linmiaohe@huawei.com>
Message-ID: <d174dcca-aad4-0534-4d6a-767e01dafd8b@huawei.com>
Date:   Fri, 30 Jul 2021 09:50:13 +0800
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On 2021/7/29 21:52, Matthew Wilcox wrote:
> 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.

I see. Will remove it. Many thanks!

> .
>