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b=LnoTTF2B7/9xXxLtLqV0L+OKJqjRY+xjxLjysetseXblaQTktKaN7zguN5l6NPVgm QZHYSfSlThR46oLYxM1Gvsr+byOBqfT+hYd9PO/NmJWBkEyOncChsseK59RXgk9l4f zQe1xEWo3NbsYiEyPdWs+pQH5Lx2WQJr27KbPChsPstoFEOoYBw6XNa2cl+7JMTo9F IoUO77kLM+A71s/9AkPOTtuBv443xTVaM0A+evBkMGAVT+jnWX6ET+nB10g64OBMfD Fy7AFApszXdLoygxETvyRtAS4/TaVdmHmpAkQAABOPsz5EcY5AjRq6m/KbttlXXH8a AHEZItBorXiMw== Message-ID: <583728ed-dc63-4685-9ac5-5a980db55973@kernel.org> Date: Mon, 26 Oct 2026 22:13:02 +0100 X-Archived-By: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 07/16] mm/shmem: avoid moving the truncation start backwards To: Zi Yan Cc: Andrew Morton , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Johannes Weiner , Vladimir Davydov , Michal Hocko , Hugh Dickins , Baolin Wang , Lukas Czerner , Carlos Maiolino , Christian Brauner , Jan Kara , Daniel Verkamp , Jeff Xu , Muchun Song , Oscar Salvador , David Stevens , "Matthew Wilcox (Oracle)" , William Kucharski , Chris Li , Kairui Song , Nhat Pham , Miaohe Lin , Naoya Horiguchi , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Chris Mason , stable@vger.kernel.org References: <20261026-fixes_shmem-v1-0-703206d5fa0c@kernel.org> <20261026-fixes_shmem-v1-7-703206d5fa0c@kernel.org> <2E377C76-D62C-4A2A-94E3-ABC40C6FCDD2@nvidia.com> From: "David Hildenbrand (Arm)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 40A3240002 X-Stat-Signature: 1iuq9nuj6mt3isp8tw53otma4j6pftni X-Spam-Status: No, score=-17.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_PASS, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=4.0.1 X-Rspam-User: X-HE-Tag: 1793049194-424300 X-HE-Meta: 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 ZimkR/9E E4FaoQxyBxaVdb/brxN5fehayUdh7ZRV4jMIi3CS1ZU3ELc3QTzZ7EPGOpoVNT+awuLGFA3kjM18xRw9a/gd6tmEx/oRquSyHKAyVZmLO15v2Oruungx8scElxKzXTh6kXxXfuk2JYy6b18L7If+r59PLkNdBGDdB6KzfFq6rfgRTvIAdplCT0eswvrOm+4JAD/yoYMS9vTCEvc7/vDZ9Iz5XYzL00W9UL65jwiq+O/ErwQyqhcOvZjJWoWT12d5QFyKgjgf0I5AUGeX75qw7/aF3tazK0qht8sOOfgUbPKJEFMP7Z97XNo1ZtIYybfvjejb3rDEoaxEYhLYG2I+CC2gpu/9KMBlJKH8PAbIIjUbE6dNXTtUjwmXpJ/ZQGqcWMQkl5oP98VAOfqsHkFRSbXQ41g== Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On 10/26/26 20:21, Zi Yan wrote: > On 26 Oct 2026, at 5:40, David Hildenbrand (Arm) wrote: > >> From: Chris Mason >> >> A nonuniform folio split can fail with -ENOMEM after splitting off some >> smaller folios. shmem_undo_range() then sets start to the end of the >> original folio, which may now lie before the truncation boundary. >> >> The final scan can consequently discard data below the new EOF, or >> keep retrying a large folio whose split point lies outside it. >> >> Keep start at least at its original value when skipping a folio after >> a failed split. The part in the truncated range has already been zeroed. >> >> Fix generated by an LLM and sent by Chris Mason in private. >> >> Fixes: 7460b470a131f ("mm/truncate: use folio_split() in truncate operation") >> Cc: stable@vger.kernel.org >> Signed-off-by: Chris Mason >> [ david: split fixes, simplify descriptions, adjust comments ] >> Signed-off-by: David Hildenbrand (Arm) >> --- >> mm/shmem.c | 8 +++++++- >> 1 file changed, 7 insertions(+), 1 deletion(-) >> > > This is fixed by Zhang Yi’s truncate_inode_partial_folio() fix[1]. > I think the commit is ad27479793682 ("mm/truncate: fix data loss > when splitting straddling large folios fails") in mm-stable but > not upstream yet. > > [1] https://lore.kernel.org/all/20260928120833.3440834-4-yi.zhang@huaweicloud.com/ How confident are we that it fixes the same issue? Does it also cover #8? -- Cheers, David