From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CF29B377A97; Sat, 17 Oct 2026 16:19:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792253952; cv=none; b=bmCG8bIUSesmgVOWebOPYzQ0LOODflL1y0/+RggzRGNHE2UGzrGv96XRaHyeY2ewTPmoR3y+bgCyi+FnPMnWhMu7seSqjDDoNkECrFmj1ybZejh3RH9h4W7v/SEQtssHs+xZBy83f7HnyRtOM2vqkphqgEKmltl4LxRh5HtPrXg= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1792253952; c=relaxed/simple; bh=qYO0m2jJ+Rmkx3lsctCEvg3umjLyYO4rtvLhKMh0rZA=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=rLBN9JTEsf90Y88JX5DJ4ldwCQsfzBEC8Iku4rHawOjrUTi+vyY8AUcJrbCiPOcY/PQ/dK4HIHApkLyhR+DTCBA8DBUmyXqJf/lrXd/bDL54eleVnwBgLEqHYxoL0L6uXi5LcuHphOv4hXhU18sMuYGpNStV2FBTXfVkHkU/5RU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=BEuZ0cc1; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="BEuZ0cc1" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 24C5F1F000C4; Sat, 17 Oct 2026 16:19:10 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1792253951; bh=FEahMrB0S2iyhCpm8lAGl7aHi/L+HMDLQ4z7t2kbE68=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=BEuZ0cc1li4Hz8Q3esPwz1Ed6f1OpHWhuFl5QHxx4MuW7BPu1vALm6hpEwnI/Si8o ghhrWuW9d8FtKlzwn5tWWoLBFIysPcUg9RVk8cMO1HiH6U3XyOaVRVCjjPowbkZfJt kEdGZSZd8QE4xycokUPJXvG3AoD/LOr1LoGqFd7Y= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Sam Edwards , Viacheslav Dubeyko , Ilya Dryomov , Sasha Levin Subject: [PATCH 6.12 285/869] ceph: fix num_ops off-by-one when crypto allocation fails Date: Sat, 17 Oct 2026 17:52:06 +0200 Message-ID: <20261017160044.380701872@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261017160036.979869304@linuxfoundation.org> References: <20261017160036.979869304@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 6.12-stable review patch. If anyone has any objections, please let me know. ------------------ From: Sam Edwards [ Upstream commit a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842 ] move_dirty_folio_in_page_array() may fail if the file is encrypted, the dirty folio is not the first in the batch, and it fails to allocate a bounce buffer to hold the ciphertext. When that happens, ceph_process_folio_batch() simply redirties the folio and flushes the current batch -- it can retry that folio in a future batch. However, if this failed folio is not contiguous with the last folio that did make it into the batch, then ceph_process_folio_batch() has already incremented `ceph_wbc->num_ops`; because it doesn't follow through and add the discontiguous folio to the array, ceph_submit_write() -- which expects that `ceph_wbc->num_ops` accurately reflects the number of contiguous ranges (and therefore the required number of "write extent" ops) in the writeback -- will panic the kernel: BUG_ON(ceph_wbc->op_idx + 1 != req->r_num_ops); This issue can be reproduced on affected kernels by writing to fscrypt-enabled CephFS file(s) with a 4KiB-written/4KiB-skipped/repeat pattern (total filesize should not matter) and gradually increasing the system's memory pressure until a bounce buffer allocation fails. Fix this crash by decrementing `ceph_wbc->num_ops` back to the correct value when move_dirty_folio_in_page_array() fails, but the folio already started counting a new (i.e. still-empty) extent. The defect corrected by this patch has existed since 2022 (see first `Fixes:`), but another bug blocked multi-folio encrypted writeback until recently (see second `Fixes:`). The second commit made it into 6.18.16, 6.19.6, and 7.0-rc1, unmasking the panic in those versions. This patch therefore fixes a regression (panic) introduced by cac190c7674f. Cc: stable@vger.kernel.org Fixes: d55207717ded ("ceph: add encryption support to writepage and writepages") Fixes: cac190c7674f ("ceph: fix write storm on fscrypted files") Signed-off-by: Sam Edwards Reviewed-by: Viacheslav Dubeyko Signed-off-by: Ilya Dryomov Signed-off-by: Sasha Levin --- fs/ceph/addr.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index 4ba991efb1ca3..355555e313102 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -1366,6 +1366,10 @@ int ceph_process_folio_batch(struct address_space *mapping, rc = ceph_move_dirty_page_in_page_array(mapping, wbc, ceph_wbc, &folio->page); if (rc) { + /* Did we just begin a new contiguous op? Nevermind! */ + if (ceph_wbc->len == 0) + ceph_wbc->num_ops--; + folio_redirty_for_writepage(wbc, folio); folio_unlock(folio); break; -- 2.53.0