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Mon, 26 Oct 2026 23:25:12 +0000 (UTC) X-FDA: 85366360464.16.CB0DD6C Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf28.hostedemail.com (Postfix) with ESMTP id 5F65CC0003 for ; Mon, 26 Oct 2026 23:25:10 +0000 (UTC) Authentication-Results: imf28.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=fnLEbREK; spf=pass (imf28.hostedemail.com: domain of david@kernel.org designates 172.234.252.31 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1793057110; h=from:from:sender:reply-to:subject:subject:date:date: message-id:message-id:to:to:cc:cc:mime-version:mime-version: content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references:dkim-signature; bh=k1Zlag/DNuh0RzHvANliw7JgpC1PTEsuWY1OUAoAx8Y=; b=Toxyu/hiS/2vxG8BK2bq94fj828D1nPL+SNFcMqKu3mMEkmN164wR2U6ly9gEC39wVgOfE QVhutV36DBekOp0fmBdka7YKAs5ngS1h48plsdmHRT3YV3kodsTxRt7Uijb5//b8M5EMKo j1opQr9Aw67qn3PItiYKKd8a76q6Vqk= ARC-Authentication-Results: i=1; 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b=fnLEbREKUCIw3x3D22mrcZnRxIlnJim3GobgkFHE+QN5rPvlAjVqot2WvzRAG1xKA 5H7kD8aq2n70G55NtkQDHhj7rYvSZefDvllEGiQIq5tVGRQZnpBGDZwlWt9kr9nXjD KT9w8JmxAv+rDcqcSEaH42DuiiIcSduz+eeDMkp8Eb1qL9xHOOIwY9t463bHSIcHJa qlO6fVGU43GVMPDuQtga3X8z75Z/YHhduXBbnXNHKzHp32YroM2VQCfMAvUvQqY/0h 5hSZkqRt/bf2hTQsQcrmxRUn1ge8dnuh0mYqMYmY13+1QLbdmwGOEsVckCCPrZ2ejt y29huz6g4kJCw== Message-ID: Date: Tue, 27 Oct 2026 00:24:46 +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 , Andrew Morton , Zhang Yi Cc: 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> <583728ed-dc63-4685-9ac5-5a980db55973@kernel.org> <0D22B04E-5730-4D3A-ADA6-9F1AF94F06AA@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: rspam05 X-Rspamd-Queue-Id: 5F65CC0003 X-Stat-Signature: gc6cegib9dtqtfdbe3o1jodohtsb6i8m X-Rspam-User: X-Spam-Status: No, score=-7.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=4.0.1 X-HE-Tag: 1793057110-659740 X-HE-Meta: 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 Pa8Bj5yC hPtXe4GTzeQbmhxUXoSLHnIK+Qm8Qcvv2a1usYtBxsRjZ5t4gYG0L9Xa6fU+KlOYd9JHfK5kIXjWjYJL1NnBA++NmyNqu4yLaMhaXZzEVMxpXAyYWxBh8idxFFqyNpnx1U8VTjP7dukKIF9yhgI4UH1gwtSUolkgrTVJPRGE3uzcYiYHy2Hxwo13fMNko305xnPQKH+054pM1Egw1oAydsxNML65bdvZYVop74T7AT6O3evCy8cVpxKi8sVqQaF6qDsiF0ncpzVQqauuxgdCSdIwNNaOaAVOsFVg81AssNv2htLDHZop10wh1GwdHkTILD3zJK6f6P8RW8wC4KbLjc4WD+pQk6hEXRL+rzy+sM+z37lg= 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 10/27/26 00:16, Zi Yan wrote: > On 26 Oct 2026, at 18:39, Zi Yan wrote: > >> On 26 Oct 2026, at 17:13, David Hildenbrand (Arm) wrote: >> >>> >>> How confident are we that it fixes the same issue? >> >> The issue here is that folio_next_index(folio) used in the mainline >> code can be an index lower than lstart and the fix is use max() >> to prevent start going backwards. (I wrote this to make sure >> I understand the issue correctly) >> >> Zhang Yi’s patch passes start into truncate_inode_parital_folio(), >> which has a new signature, and it is updated with the folio’s index >> within the [lstart, lend] range at the beginning. >> >> So this patch fixes the issue at the caller and Zhang Yi’s patch >> fixes the issue inside truncate_inode_partial_folio(). >> >>> >>> Does it also cover #8? >> >> No, patch 8 is still needed. I am checking it on how to rebase it >> on mm-stable. >> >> Patch 9, 10, 11 might need rebase on mm-stable too. >> >> Since these patches are on top of mainline instead of mm-stable, >> you will need to rebase them. IIRC, Zhang Yi’s patches are needed >> for ext4 + iomap buffered I/O conversion. Hmm, but Zhang Yi’s >> ext4 iomap patches has landed in mainline but its dependency >> is not. So we cannot drop Zhang Yi’s patches and ask for a >> resend. Adding Zhang Yi here. > > To clarify the dependency, without Zhang Yi’s > truncate_inode_partial_folio() patchset, the ext4 + iomap changes > would cause data loss. We probably want to get Zhang Yi’s patches > in first to avoid that. Ugh, what a mess. > > Patch 7 to 11 do not apply cleanly on top of mm-stable due to Zhang Yi’s > truncate fix, where > > 1. patch 7 can be dropped as I discussed above, > 2. patch 8 needs a folio->mapping guard for the added statement, > 3. patch 9-11 can be applied with fuzzy, but I need to look into > them about functionalities before fully trust what LLM says. Yeah, let me take a look tomorrow. I cannot put into words how much this shmem + pagecache shite annoys me. What a piece of crap people created here. And looking at the massive changes to fix stuff, what a piece of crap people are creating. I better go to sleep now :) -- Cheers, David