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Fri, 24 Oct 2025 08:46:59 +0800 Message-ID: <6a0cd943-a3cf-41fe-b666-47d250413a77@linux.alibaba.com> Date: Fri, 24 Oct 2025 08:46:58 +0800 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3] mm/shmem: fix THP allocation and fallback loop To: Kairui Song , linux-mm@kvack.org Cc: Andrew Morton , Hugh Dickins , Dev Jain , David Hildenbrand , Barry Song , Liam Howlett , Lorenzo Stoakes , Mariano Pache , Matthew Wilcox , Ryan Roberts , Zi Yan , linux-kernel@vger.kernel.org, Kairui Song , stable@vger.kernel.org References: <20251023065913.36925-1-ryncsn@gmail.com> From: Baolin Wang In-Reply-To: <20251023065913.36925-1-ryncsn@gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam01 X-Stat-Signature: fo44iysg8juhqxj9skqww71u95aqx4ne X-Rspam-User: X-Rspamd-Queue-Id: C7CD6C0006 X-HE-Tag: 1761266824-835760 X-HE-Meta: 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 HImveYVr pJAFX0CFCcA0PLt4mR2I+ACg5R8iBP9PScm/0we5uN4LOIZoRGuYglNfyG5ga+ZohsGOqTbgNp/b1qfjmpMZlXflJwYDTg76j5XN/Etznkjsf6oVFLzHng+q1y8ibarF3bGD1j3y160sxKzhqAlGdwFsLZe//F9pqEnKuVx+HEXKqwWyOkHzW4Koh+OABJGBc62v24wsGWkbFD/TAcT3vbETI5brb7+N23PoEwnNQ5GyABw8T9kfoOeBNp/B+8+cpOa0fvIdVF7P6OtpkcmFPgaUIyNppE+Q1EprLx6SBLcyQDbh6paSiNdFwuNYL0Z4+/zLnY1TIF9KpVhmZc8VkRwBmjFI4vXVGKscU1+c12PnEAkoTUbpaeHV4TA== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 2025/10/23 14:59, Kairui Song wrote: > From: Kairui Song > > The order check and fallback loop is updating the index value on every > loop, this will cause the index to be wrongly aligned by a larger value > while the loop shrinks the order. > > This may result in inserting and returning a folio of the wrong index > and cause data corruption with some userspace workloads [1]. > > Cc: stable@vger.kernel.org > Link: https://lore.kernel.org/linux-mm/CAMgjq7DqgAmj25nDUwwu1U2cSGSn8n4-Hqpgottedy0S6YYeUw@mail.gmail.com/ [1] > Fixes: e7a2ab7b3bb5d ("mm: shmem: add mTHP support for anonymous shmem") > Signed-off-by: Kairui Song > > --- LGTM. Thanks. Reviewed-by: Baolin Wang