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=1794273673; b=44bNym0AxaA4WpRkFAkWlZjFdIP8IUK0Nr7OEH2ggI15rncKi40klRen5AfajraNu8tx YZjlYwG9ZKMlRPxNStWvQKRqkjCqDSK6Y+urlBQzAfaY4Np+Iv0JKBpCxVVANmZDcshTQ rUUsEEoD7veMTDJpo3VJmBgE5VhImcL8RZbJm6uzmw5ibxiGCThCY6BmqJCwibWHU1Zyq 506JAWdXXvdm1Un4z5ytFDnCru9XYEgSjixTFCBAkCeZ6XYA+zXVvq6sPUV0TGK6hNLU6 EG4qEFqAyjuMZ+/dBAQ0hC46rnJBnBINaN8fiQ6MdcY11zIuprg7EwO/jluBF8GkAFg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794273673; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: MIME-Version:Content-Type:Content-Transfer-Encoding; bh=u3wCMOTkjQeEUOfTL1NzCQqnNAKfGzDHos80PTRRm2o=; b=mI5YcaX80NNV4s26p/pUmfVNDLyg05cCTFqVrO8l+CQNXe4y+S4yWXHt7Caz6mYVEDBG bsTFuWX/onnU/9C3RcqQhBE4IpBd33vXbCBivdHqbV9p1WwK97oC94hWy7ZxxO2EKxy52 6WFaL9ffBGUAJMrX5+KRLbFpxPyqG1oW2lnqAlZVTjLDm6zX9I/qHPqad2LmW5ULhMVB5 9CZCXfCeeF/n6hzgVE5J56ri4cPPaEiZPiYNcu4r8s2NoGDkvYVtEsBvfhxBkIjF5nDDl C1o4zZAml2+rRmYijkomGeMEsq78fs808PIKWEkZt6k8VnnCb5J0fUyQcwwjEnzPXkw== 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=FqZClKAJ; 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 60B22606A338 for ; Tue, 10 Nov 2026 01:21:13 +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=FqZClKAJ Received: by smtp.kernel.org (Postfix) with ESMTPSA id B0AED1F008A1; Tue, 10 Nov 2026 01:21:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1794273673; bh=u3wCMOTkjQeEUOfTL1NzCQqnNAKfGzDHos80PTRRm2o=; h=From:To:Cc:Subject:Date; b=FqZClKAJEpa9kj6Tjc/mtOopqORCNsyOZ6vCIfER14kp3G2YCKNrjuZcGprren+H7 Why95WS5H5Zfef/WLQ9vIZwvDvZ3+SMK46koZ4m+Er2JPqzaEgYKrGwyw4gVA1MZZH vkuBS8kIwYeRALg5ehFYfRlhz2xTnx+YthzS9tkl3mT5k2Xql+9rYOG3JnQdov2Yyz HgxkjOLod+WpOqPafGtFBzyWukTTwH1nCOPY1Hrhvu/i/JD62QoRSoqv6cJ8V0xxP9 PZ1SBuBbQgbdqYTxUAj8jrLFeBzo5fLNvd9FC44lmOK9oO0cDbmAPlXewu/X0zTeaE dqqVZElBBPYRA== 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 5.15-stable tree Date: Mon, 9 Nov 2026 20:21:07 -0500 Message-ID: <20261109202107-failed-5.15-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 5.15-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-5.15.y git checkout FETCH_HEAD git cherry-pick -x dc24e273244e9d712257d5a6c20a32c7f5ca84e6 # git commit -s git send-email --to '' --in-reply-to '20261109202107-failed-5.15-dc24e273244e@kernel.org' --subject-prefix 'PATCH 5.15.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