From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 1C79D606A31E for ; Mon, 26 Oct 2026 23:19:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=lists.infradead.org header.i=@lists.infradead.org header.a=rsa-sha256 header.s=bombadil.20210309 header.b=TERIusYy; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=I8iKZ2Bw DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Cc:To:In-Reply-To:References :Message-Id:Content-Transfer-Encoding:Content-Type:MIME-Version:Subject:Date: From:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Unsubscribe-Post: List-Owner; bh=H94VuGtG6BpRFhvFPWMMDLKdr76dloMuoWr2DscOb8Y=; b=TERIusYyK597zc cql+kIZNV2YhJVXQ3AP+Pf32Xv0tRA95pRotGZPCk8gmzZsB7V4P7ZYif/0w5Fhq0Acg4hnwRfk5K eOzf6z6BddInpfeLPSy6DPTA7LCCvPQvPB2d3QCoDghukQ9CP/D/eYVtqpYOxVAOdL1yFDdQXyd9O uLgquIqEfs8dVoADyk45mwLF/pexNgQC2UZ3Cp4e4XMiqecpBQMgnvJXhP/S0N5VPFThh3ObLUyrS XVeX88rQAOW8xFVMd8vAope7JgscQPd+Ej3lS0690uY2yIUpQTfEmgvOTlhOaQwaGFvZGWKkxg1ji CN6stFFG2S64F+iaKpGw==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.100.1 #2 (Red Hat Linux)) id 1xLTyW-00000003PEW-3Ep1; Mon, 26 Oct 2026 23:19:32 +0000 Received: from sea.source.kernel.org ([172.234.252.31]) by bombadil.infradead.org with esmtps (Exim 4.100.1 #2 (Red Hat Linux)) id 1xLTyU-00000003PEE-36s6 for kexec@lists.infradead.org; Mon, 26 Oct 2026 23:19:30 +0000 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 8687143E9C; Mon, 26 Oct 2026 23:19:29 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 213BB1F01828; Mon, 26 Oct 2026 23:19:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793056769; bh=H94VuGtG6BpRFhvFPWMMDLKdr76dloMuoWr2DscOb8Y=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=I8iKZ2BwWhRlGZKB5MDnIdv4P3Hsc5OC2Y8e+6o+Rsh4VMxS9ryGLhNAlqek22Dzv aOPMjgNb3WIn+nbeA4Bl2OmEam6tNWnp7KP4P7Sq1Otq6EAEt/O6Cj5WgRFOq/NfHL yBlHn5kU3RWZscpHxcqsXYx72K358Q3ElDuWj6xww/Ko7kKUPtLC86boj4WebUtPkx xUkJamkiias1T6VaQVSwXWqfCm0Hp/O1QtXuUJ8+Z9MZCKAh2yqRJSLB67hCMzLNcP SK31F0/mluevSG3880IFFKBePRADDkMxPRbxbohBQaya9pGvGPIvqBFBnXxalxeImC /O0s/E/Fmnv9A== From: "David Hildenbrand (Arm)" Date: Tue, 27 Oct 2026 00:17:25 +0100 Subject: [PATCH 05/46] mm/truncate: look again if a folio left the mapping X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261027-fixes_core-v1-5-6f74bec9a5bb@kernel.org> References: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> In-Reply-To: <20261027-fixes_core-v1-0-6f74bec9a5bb@kernel.org> To: Andrew Morton , Johannes Weiner , Michal Hocko , Qi Zheng , Shakeel Butt , Lorenzo Stoakes , Kairui Song , Barry Song , Axel Rasmussen , Yuanchu Xie , Wei Xu , Baoquan He , Baolin Wang , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , Kees Cook , Peter Zijlstra , Jann Horn , Pedro Falcato , Hugh Dickins , Pasha Tatashin , Pratyush Yadav , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Lance Yang , Rik van Riel , Harry Yoo , Alistair Popple , Nico Pache , Ryan Roberts , Dev Jain , Usama Arif , Kiryl Shutsemau , Matthew Brost , John Hubbard , Peter Xu , Will Deacon , "Aneesh Kumar K.V" , Nick Piggin , Oscar Salvador , Minchan Kim , Muchun Song , Xu Xin , Chengming Zhou , Chris Li , Kemeng Shi , Nhat Pham , Youngjun Park , Gregory Price , Joshua Hahn , Rakie Kim , Ying Huang , Jason Gunthorpe Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, kexec@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-arch@vger.kernel.org, linux-cxl@vger.kernel.org, stable@vger.kernel.org, Josef Bacik , "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3123; i=david@kernel.org; h=from:subject:message-id; bh=LCXJvaCAxM8DYeEIbqCybn9PrvO5kcWMg/840Mus1kc=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLLu35/c8ljL9OqVuwY9+3suFMYJTzv25M8VW/u/KRKH4 g0d8qyqOkpZGMQ4GGTFFFmCgu8bvHy5rrbajY8ZZg4rE8gQBi5OAZjInEBGhr25c3sdnCbE9kXY 7Lby7DvHeGTLeZsbTo/qpQ5tmW5moM7wV4x73/kDyy57H/0wL6f0q3Nz/cVdR5zMGn/pftq/I7l 0AwMA X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-BeenThere: kexec@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "kexec" X-Spam-Status: No, score=-19.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,DKIM_VALID_EF, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 invalidate_inode_pages2_range() skips a folio which no longer belongs to the mapping by the time it has got the folio lock, on the assumption that somebody else has removed it from the page cache. But the folio may have been replaced, and then there is a new folio with the same data at that index. For most cases, like folio migration, that is impossible. However, collapse_file() only checks the refcount of the old folios, under the i_pages lock, and relies on their folio locks from there on. That works for users which repeat the lookup when they find folio->mapping changed. The following scenario is, however, possible: CPU0 pwrite(O_DIRECT) CPU1 collapse_file() kiocb_invalidate_pages() read the folio (old data), lock it refcount check the write completes copy to new_folio kiocb_invalidate_post_direct_write() find_get_entries() -> old folio folio_lock() ... xas_store(new_folio) folio->mapping = NULL folio_unlock(folio) folio->mapping != mapping -> continue In that scenario, the collapsed folio with the data from before the write stays in the page cache after the write has returned. This used to be impossible, as khugepaged only collapsed files that nobody had open for writing. Restart the lookup at that index, like shmem_undo_range() does. The same problem seems to exist in truncate_inode_pages_range() as well when truncate_inode_folio() fails, so handle it there as well. Fixes: 1b6444331beb ("mm/khugepaged: enable clean pagecache folio collapse for writable files") Cc: stable@vger.kernel.org Reported-by: Josef Bacik Signed-off-by: David Hildenbrand (Arm) --- mm/truncate.c | 17 +++++++++++++++-- 1 file changed, 15 insertions(+), 2 deletions(-) diff --git a/mm/truncate.c b/mm/truncate.c index 733d2713a875a..6d8c0ec4623fe 100644 --- a/mm/truncate.c +++ b/mm/truncate.c @@ -499,7 +499,15 @@ void truncate_inode_pages_range(struct address_space *mapping, folio_lock(folio); VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio); folio_wait_writeback(folio); - truncate_inode_folio(mapping, folio); + if (truncate_inode_folio(mapping, folio)) { + folio_unlock(folio); + /* + * Folio might have been replaced: look it up + * again. + */ + index = indices[i]; + break; + } folio_unlock(folio); } truncate_folio_batch_exceptionals(mapping, &fbatch, indices); @@ -760,7 +768,12 @@ int invalidate_inode_pages2_range(struct address_space *mapping, folio_lock(folio); if (unlikely(folio->mapping != mapping)) { folio_unlock(folio); - continue; + /* + * Folio might have been replaced: look up + * again. + */ + index = indices[i]; + break; } VM_BUG_ON_FOLIO(!folio_contains(folio, indices[i]), folio); folio_wait_writeback(folio); -- 2.43.0