From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794273093; b=h7a9PBMW51M+6c+sCwd4TkWuqi47fpTYH2OWS0cODFPxbnEskhzSBRPbjfUq2aGoG+Ym ldFWpUihMqKwbmZeLy8cG97xTqQPYLYhH2eTAPZ0PtLiBWXoEpz0uOeGhTkj8n7ONxgPt BEAWXqbaxJKiEgFelNxIFVV43hCcA+BX98L81awMoT6Vzkso3yXYe6GQzmRP+kub16Rvz gY3by7+58jU4VpOJgWm80fFDHhqWPLB59KKHAokIRwe8L2gZGiRhg4LvZwCSM84mEVj9h 7M2uvSijxA7P3lnHxm8ZbrWfkFQ8R2WBILrRpkUM8ZAKodOY/z7l2mqS4T5LAwrw58g== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794273093; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=vEfJGFxMMjdUTV91b5nnNtb+AMI0qXCVXZbbJHISd0s=; b=DhplcGg1Bm7usdmDsAZaIvrkCk5Ejcx0pKVCLFefb5ZNYVb7sEs2xVufB2fmHjL+WUqV 4FEl3Hj4IaSa1KBMu6hP9VQHgwvLc6N2YxGF+LcgbC0b4UnrxtS56X5RgYwZ5OL35jmMq 76oWOD70vVyDnATyvDRErrgpnv6lBlZGZjFSU1eoJZ/zf3PNCtlDL5vOtMQB/O74jSF2Y Aso5iyf37Ghqp9VAbQgp7jlnMaEMZNdsItiNcXOCACoT+qVbt3ri3/B/EQnXfKX/oNeUJ paG3CQzDjuDfgcSb46WSQclMjQ55n7dzBBS6IFYFgsDUrTTR9nxI5VCwNdFzhbh+S/g== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=g3pegHvp; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id B6BF9606A31C for ; Tue, 10 Nov 2026 01:11:32 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20260515 header.b=g3pegHvp Received: by smtp.kernel.org (Postfix) with ESMTPSA id D98441F0089F; Tue, 10 Nov 2026 01:11:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794273092; bh=vEfJGFxMMjdUTV91b5nnNtb+AMI0qXCVXZbbJHISd0s=; h=From:To:Cc:Subject:Date; b=g3pegHvp+xlhTMKJcnEqtw924ClyCLo6EzMfskoTSR3dZGevDxEl3BrHLmVxicaxi uM3uflTm9bXVVSL/iDC4rWjgMumAmc7kal1FzrQ5jlWuxA65uD6k8a4Q8AZxFbGFKO wRpXJLDrE+NKvb05rfLUd2kP9VwpNEWfH2yskUpjV62TBk8sa1Zb5ydd4n1LnWePaS mKgagezaauo89tCdVP9w8BHadSzFnZm2qZwAVY51E4S/grMIAynC0MJp+Zc4BY+f63 czRAdQmkTD6tUkwRdGs+/vxedrk+7dVaXjyvQHksaFIWyRsJvYHNmEoEDgJ55pgU+H Rw5/9jZZuWT6Q== From: Sasha Levin To: josef@toxicpanda.com, riel@surriel.com, usama.anjum@arm.com, ziy@nvidia.com, david@kernel.org Cc: stable@vger.kernel.org Subject: FAILED: patch "[PATCH] mm/filemap: read mapping->a_ops->free_folio under i_lock" failed to apply to 6.6-stable tree Date: Mon, 9 Nov 2026 20:11:30 -0500 Message-ID: <20261109201130-failed-6.6-dc24e273244e@kernel.org> X-Mailer: git-send-email 2.53.0 X-Mailing-List: stable@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.6-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . To reproduce the conflict and resubmit, you may use the following commands: git fetch https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/ linux-6.6.y git checkout FETCH_HEAD git cherry-pick -x dc24e273244e9d712257d5a6c20a32c7f5ca84e6 # git commit -s git send-email --to '' --in-reply-to '20261109201130-failed-6.6-dc24e273244e@kernel.org' --subject-prefix 'PATCH 6.6.y' 'HEAD^..' Thanks, Sasha ------------------ original commit in Linus's tree ------------------ >From dc24e273244e9d712257d5a6c20a32c7f5ca84e6 Mon Sep 17 00:00:00 2001 From: Josef Bacik Date: Sat, 31 Oct 2026 10:39:35 +0100 Subject: [PATCH] mm/filemap: read mapping->a_ops->free_folio under i_lock 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 Tested-by: Muhammad Usama Anjum Reviewed-by: Zi Yan Link: https://patch.msgid.link/20261031-fixes_core-v3-6-d6437171ecc3@kernel.org 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) -- 2.53.0