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 857F3606A31D for ; Mon, 26 Oct 2026 23:19:51 +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=KUd4ools Received: by kanga.kvack.org (Postfix) id 908016B05BD; Mon, 26 Oct 2026 19:19:50 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 8DF176B05BE; Mon, 26 Oct 2026 19:19:50 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 7F52C6B05BF; Mon, 26 Oct 2026 19:19:50 -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 5C8606B05BD for ; Mon, 26 Oct 2026 19:19:50 -0400 (EDT) Received: from smtpin12.hostedemail.com (lb01a-stub [10.200.18.249]) by unirelay10.hostedemail.com (Postfix) with ESMTP id BC6F9C0849 for ; Mon, 26 Oct 2026 23:19:49 +0000 (UTC) X-FDA: 85366346898.12.B76E446 Received: from sea.source.kernel.org (sea.source.kernel.org [172.234.252.31]) by imf07.hostedemail.com (Postfix) with ESMTP id EEB6740007 for ; Mon, 26 Oct 2026 23:19:47 +0000 (UTC) Authentication-Results: imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=KUd4ools; spf=pass (imf07.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-Seal: i=1; a=rsa-sha256; d=hostedemail.com; s=arc-20220608; cv=none; t=1793056788; b=2P45jHG5Uz2hwQ9SHhK2a2DbuP6tolCrtUGmXMysrprUP8AO/z9/V0q5sR/kpwS3RRjd2B cGdyilju4BornSeGbYI7dnVXAS3pMLynLAGA+XNoCvxMRdVXfSXzV0ybXV5LqZ5WeylYH4 paIO45kyX+dr9fyCX3baejgKd7unyIk= ARC-Authentication-Results: i=1; imf07.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20260515 header.b=KUd4ools; spf=pass (imf07.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=1793056788; 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=rRXrA/tyStkBmC7dglbBDKVTBfaDXW25Ud/zHKaz2Ig=; b=n3hrgimbGYJMeQcsl7NvtTb6g5wMAxT8UfPIitavxCLRBXvznky9M6NGhoDmPszn7Jz187 m29y/F7tCR9eZFG3xTymnfg7W3FqWDhqjtyjfOQ2wVQK2hty9boiikx3TZdCEwMkQkPptX vyL1xyqUPK13KW5vpzQBHGh+B/znu6Y= Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) by sea.source.kernel.org (Postfix) with ESMTP id 24D0643BF0; Mon, 26 Oct 2026 23:19:47 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 116581F031E1; Mon, 26 Oct 2026 23:19:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1793056787; bh=rRXrA/tyStkBmC7dglbBDKVTBfaDXW25Ud/zHKaz2Ig=; h=From:Date:Subject:References:In-Reply-To:To:Cc; b=KUd4oolszt2QIPW7WtveUCPtMmmqmnf7waWs2nfCbzJeAcTAHVmBk0D3JQc3Io4PS rR+U4nUnLeY1sUJzPA7GpkTQNcyMET0bo3nYYpqYCDvmx/jgOLmjLPMkjKvQN8JsFG hQnH/+x9Z+7koraSDGlRHmAcUVAx068DAkkSDdPDWTfzcFrJPtZ2GRcAGW8fpr+Ugd CswVpJ7Ydma41W/jftH7QT3TZoCDIPCOPel25/UbeqDkX8FX0hG8otDam5riyDC5OP qeKhgIWGvEDFp9qsdAw15fwMyqP3+7fcGO7T3lZaj357eyUeo7dS1Oj2XQmmvBC+Yc cB5Gq3lGzCBGQ== From: "David Hildenbrand (Arm)" Date: Tue, 27 Oct 2026 00:17:26 +0100 Subject: [PATCH 06/46] 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: <20261027-fixes_core-v1-6-6f74bec9a5bb@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, Josef Bacik , stable@vger.kernel.org, "David Hildenbrand (Arm)" X-Mailer: b4 0.16.0 X-Developer-Signature: v=1; a=openpgp-sha256; l=3678; i=david@kernel.org; h=from:subject:message-id; bh=b6PA7tE/rZMjLIceJa9YiiSjeJMFaXXevLttm/76m88=; b=owGbwMvMwCF2/OVpCdfQ3ZWMp9WSGLLu35+cfMGKMVghRr+Z4+jbqxncs+c4PLu1/+7j/7qPl p1a8OepcUcpC4MYB4OsmCJLUPB9g5cv19VWu/Exw8xhZQIZwsDFKQATkTJkZJiTcvdRWKK80bdZ VeyPMrIkeX6e4Qozka6SeSBldurjNmNGhrO2+UuWe+7JdFLcu/1LecLJIzfP3AnZuWHfRqNGl86 J4UwA X-Developer-Key: i=david@kernel.org; a=openpgp; fpr=1BD9CAAD735C4C3A460DFCCA4DDE10F700FF835A X-Stat-Signature: hwqk3k76jk4tmojq45fj6bq9nqhjiaf5 X-Spam-Status: No, score=-19.1 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-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: EEB6740007 X-Rspam-User: X-HE-Tag: 1793056787-801641 X-HE-Meta: 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 aK1Q6inG mFMe4g/Z5lsMgaZzjsPmzfZYELlGa5/mJsr6g2v5kRu8gsHKjItqAvDP1YOl5aH3g1tmfEXrB2moULfPduJ6CJUviWpHtvxccsKYG4Glkkd7DH1s0QOhveabL4y4ljQuyKsSvIbof0Scmo4RMQz4goZ1a/INf/s3amjyR4i4vuOMUWunt0tIR5tOyhoVXat4bKbTGVw3o8u5r6+otXpjARQf+H/kJe712wZrWVe9jLQr5YamKhqyp+kLpAnNtt8rufirEPD1XIOlWSrKCaNBUj/3e4Eac8e8IiOLMITf3U5yg/k8oGUxBFC8fRd5jrK/3+5toUbxFrJ4dIv5PRTPiC66mz7Jw/QnTB8C/27i5kC7lsNdy3f6tEnSAS7tG1ISZQilcmGVpB44hoJqG+WCU2tNbCOu5q+09JEw6WbOWcCapdKs= 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 ] 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 b74bc1e5015c6..906b013c11eb3 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