linux-kernel - Re: [PATCH v3] mm/shmem: fix THP allocation and fallback loop

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Message-ID: <6a0cd943-a3cf-41fe-b666-47d250413a77@linux.alibaba.com>
Date: Fri, 24 Oct 2025 08:46:58 +0800
From: Baolin Wang <baolin.wang@...ux.alibaba.com>
To: Kairui Song <ryncsn@...il.com>, linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>, Hugh Dickins
 <hughd@...gle.com>, Dev Jain <dev.jain@....com>,
 David Hildenbrand <david@...hat.com>, Barry Song <baohua@...nel.org>,
 Liam Howlett <liam.howlett@...cle.com>,
 Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 Mariano Pache <npache@...hat.com>, Matthew Wilcox <willy@...radead.org>,
 Ryan Roberts <ryan.roberts@....com>, Zi Yan <ziy@...dia.com>,
 linux-kernel@...r.kernel.org, Kairui Song <kasong@...cent.com>,
 stable@...r.kernel.org
Subject: Re: [PATCH v3] mm/shmem: fix THP allocation and fallback loop



On 2025/10/23 14:59, Kairui Song wrote:
> From: Kairui Song <kasong@...cent.com>
> 
> 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@...r.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 <kasong@...cent.com>
> 
> ---

LGTM. Thanks.
Reviewed-by: Baolin Wang <baolin.wang@...ux.alibaba.com>