From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.subspace.kernel.org (Postfix) with ESMTP id CA875606A31F for ; Thu, 29 Oct 2026 20:35:02 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key, unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=m8stvVUt Received: by kanga.kvack.org (Postfix) id E4D856B00EF; Thu, 29 Oct 2026 16:35:01 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id DFE2A6B05B2; Thu, 29 Oct 2026 16:35:01 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id CED5D6B05BC; Thu, 29 Oct 2026 16:35:01 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0010.hostedemail.com [216.40.44.10]) by kanga.kvack.org (Postfix) with ESMTP id A5FD76B00EF for ; Thu, 29 Oct 2026 16:35:01 -0400 (EDT) Received: from smtpin29.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id 28F8DC04D7 for ; Thu, 29 Oct 2026 20:35:01 +0000 (UTC) X-FDA: 85376818002.29.CBA2A87 Received: from tor.source.kernel.org (tor.source.kernel.org [172.105.4.254]) by imf30.hostedemail.com (Postfix) with ESMTP id 6A0E28000E for ; Thu, 29 Oct 2026 20:34:59 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=m8stvVUt; spf=pass (imf30.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 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=1793306099; 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=KxYr7Sm6OEegxhd0iVI9DwNJDZ8ymD/S/fyvDRwEbZs=; b=E2GzWTXRx40r5TQA2h7/8JOqw2W3CyOJAJDWzRVcg3AAARiejQv1b4dNXhJAsxGksELZNo FRk3ZEZ4whxrr80Bdb7doKYMdkjJnnqmMVhhqQk8hrB8duL7/y2/gWhe3D1a6FCtXk4trX TP+e0sV+WwQi+Q1MyEUsUEc5Do8e+v8= ARC-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793306099; b=kGKYLr/sFDxhIQZkC5v2Z6/wswDm7rYpFKz6dbfhXUvrqv0jvsLllx8Hykc5Rk5WAj//7v b2MG5qB0sbksPYeo4+YtbJx/Z4rYZmzWvrBlLy6cOfGDWRKIpYHoX5khauTpWLbDc/pk84 kbCrPBksyyO8II1teCtWb5knQgYrTew= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=m8stvVUt; spf=pass (imf30.hostedemail.com: domain of david@kernel.org designates 172.105.4.254 as permitted sender) smtp.mailfrom=david@kernel.org; dmarc=pass (policy=quarantine) header.from=kernel.org Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by tor.source.kernel.org (Postfix) with ESMTP id F189F605CA; Thu, 29 Oct 2026 20:34:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 3413D1F01826; Thu, 29 Oct 2026 20:34:44 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793306098; bh=KxYr7Sm6OEegxhd0iVI9DwNJDZ8ymD/S/fyvDRwEbZs=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=m8stvVUtaQ1zzXBZo9b4DXWtjQAwfK94PwzaJ/eyWlctn2jfEk/kIccDZT4yzRzTV xUwhkYp4JFgiEQbnWZ93UJ8mt2S+Web/7pzGe0SpkYI6oocQZiPLpHT73hP74roi3D Yr+BUk3pE/quR4/Ig1StPmT2uOE6hcTPcUKEVJ/Lv5UMx5k4G06IaFelmWSX8rEvzA ylUcnc1dGEcjLRHd7oeEGKeFW/1BtT4p1adLyRlFCZ+tJKXJz8Wd3CUiSLA5LptqrQ Lopmi7EvwC7Ts8BZAb+MLwTj6XScPpqfDLchayfM4KgiBF4iArRR7JwJRL9P4FDqwX OjQa5upyhqaBA== From: "David Hildenbrand (Arm)" Date: Thu, 29 Oct 2026 21:33:01 +0100 Subject: [PATCH v2 06/47] mm/filemap: read mapping->a_ops->free_folio under i_lock X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Message-Id: <20261029-fixes_core-v2-6-a64ce7f83abb@kernel.org> References: <20261029-fixes_core-v2-0-a64ce7f83abb@kernel.org> In-Reply-To: <20261029-fixes_core-v2-0-a64ce7f83abb@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, Josef Bacik , stable@vger.kernel.org, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3722; i=david@kernel.org; h=from:subject:message-id; bh=QdrOe18hQtm70tC+kr29IxB4g7ljmyzLHze5efGpjA8=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLIer22pSz/Yr2rC1Wyzv75dSO/9zxyjvv59K06tKJoq7 jFNwXtbRykLgxgHg6yYIktQ8H2Dly/X1Va78THDzGFlAhnCwMUpABOpqmNkOBziF+Ztzcv74uOs M8/99SO2irj9uWaeLBJ/3eKDe2PYO0aG15ob3G0e/LRW1gmRjJv2v3bv/R1bGjMeL888u3fdBef zDAA= X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 6A0E28000E X-Stat-Signature: pik9zkam4rpmzes98o5ei1biekuniziz X-Rspam-User: X-Spam-Status: No, score=-18.8 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_GIT autolearn=unavailable autolearn_force=no version=4.0.1 X-HE-Tag: 1793306099-304944 X-HE-Meta: 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 gE67HNSc CHb6ebP4kKu/94D1FEGcDG9YQqqbHZ9Ab94rTQ2EaSyEI+S6+S3ya06WgmKuHZjbmWDcnQ7rnyP1qgMtSaHjS5xGwbopSq9UGJLlf7bdNcDC86pFkXYpLgVYrAH6LUPsBwkmak6SFYcfo9epKEVzDHzFNJsUYGmXKGowj0QqdzzyXXYvVbTK3BgOoXCfZeDlAHGQaidpxHH2HbQ6hgsMNAgzzlA9dog3VvyHc0WsP4hejPR988X6gojFxRMoGIWIVfwthdbwtPTLZjcqPSGblMvntOGaTj/DFY9EHXpS88xxDL9zkAbQU7sGKuScdbquGKSRDdbGg2/mL97BWNxpUJr2TrDEYRMzsJGYqYDiNQemULCM4uSkIHDIOYzidRU89HywrPdnjsceA9UTF8hgmZt9268pqU/Obe/lh2nvNr+tggBDkVsvSfEXdLHT7kPay3SWWTznqYP5bv/X823f3OW02X4RxCLYOMMJLlFxHurrwAO8= 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 From: Josef Bacik memory_failure() -> ... -> filemap_remove_folio() can read mapping->a_ops after the inode has been freed. Once the folio is deleted from the pagecache it no longer pins the mapping, so after i_lock is dropped e.g., a concurrent final iput() can evict and free the inode before filemap_free_folio() looks up mapping->a_ops->free_folio. Most callers hold a reference on the inode, but not all. Documentation/filesystems/vfs.rst explicitly states that ->free_folio() must not assume the original address_space mapping still exists. Fix it by loading ->free_folio while i_lock is still held, similar to what folio_unmap_invalidate() does. Inline filemap_free_folio() into its remaining caller such that delete_from_page_cache_batch() also just loads the callback before dropping the i_lock. The bug was found by code inspection and has not been reproduced. Fix generated by an LLM and sent by Josef Bacik in private. Fixes: 59c66c5f8c4f ("mm: factor out page cache page freeing into a separate function") Cc: stable@vger.kernel.org Signed-off-by: Josef Bacik [ david: get rid of filemap_free_folio() entirely; improve patch description ] Reviewed-by: Rik van Riel Signed-off-by: David Hildenbrand (Arm) --- mm/filemap.c | 29 ++++++++++++++--------------- 1 file changed, 14 insertions(+), 15 deletions(-) diff --git a/mm/filemap.c b/mm/filemap.c index b74bc1e5015c..906b013c11eb 100644 --- a/mm/filemap.c +++ b/mm/filemap.c @@ -227,18 +227,6 @@ void __filemap_remove_folio(struct folio *folio, void *shadow) page_cache_delete(mapping, folio, shadow); } -static void filemap_free_folio(const struct address_space *mapping, - struct folio *folio) -{ - void (*free_folio)(struct folio *); - - free_folio = mapping->a_ops->free_folio; - if (free_folio) - free_folio(folio); - - folio_put_refs(folio, folio_nr_pages(folio)); -} - /** * filemap_remove_folio - Remove folio from page cache. * @folio: The folio. @@ -250,6 +238,7 @@ static void filemap_free_folio(const struct address_space *mapping, void filemap_remove_folio(struct folio *folio) { struct address_space *mapping = folio->mapping; + void (*free_folio)(struct folio *folio); BUG_ON(!folio_test_locked(folio)); spin_lock(&mapping->host->i_lock); @@ -258,9 +247,12 @@ void filemap_remove_folio(struct folio *folio) xa_unlock_irq(&mapping->i_pages); if (mapping_shrinkable(mapping)) inode_lru_list_add(mapping->host); + free_folio = mapping->a_ops->free_folio; spin_unlock(&mapping->host->i_lock); - filemap_free_folio(mapping, folio); + if (free_folio) + free_folio(folio); + folio_put_refs(folio, folio_nr_pages(folio)); } /* @@ -320,6 +312,7 @@ static void page_cache_delete_batch(struct address_space *mapping, void delete_from_page_cache_batch(struct address_space *mapping, struct folio_batch *fbatch) { + void (*free_folio)(struct folio *folio); int i; if (!folio_batch_count(fbatch)) @@ -337,10 +330,16 @@ void delete_from_page_cache_batch(struct address_space *mapping, xa_unlock_irq(&mapping->i_pages); if (mapping_shrinkable(mapping)) inode_lru_list_add(mapping->host); + free_folio = mapping->a_ops->free_folio; spin_unlock(&mapping->host->i_lock); - for (i = 0; i < folio_batch_count(fbatch); i++) - filemap_free_folio(mapping, fbatch->folios[i]); + for (i = 0; i < folio_batch_count(fbatch); i++) { + struct folio *folio = fbatch->folios[i]; + + if (free_folio) + free_folio(folio); + folio_put_refs(folio, folio_nr_pages(folio)); + } } int filemap_check_errors(struct address_space *mapping) -- 2.43.0