From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 05D1B348469 for ; Mon, 4 May 2026 08:50:04 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777884605; cv=none; b=EJAP+qT14LAauHfEaCU2uHp2ioi5+2R5I2IQ90fnOvibmbbha8EVx7NrYixxWDMF4yOQFR3/NxQmbE4/Pyc/Ee1VoW9DsqRf/gJwl3Ak9apciv9IXj2ZstkN9zjD68hg2x5QlMAqgoyKoDxpAqQ+qof9eh5pfA60bQQsu1QwL+U= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1777884605; c=relaxed/simple; bh=l7ehv2zbwR50zFLpHr+/piHe/PVXi5NUH6E/2RvgS+c=; h=Subject:To:Cc:From:Date:Message-ID:MIME-Version:Content-Type; b=H1DnNwnUbu8VqHQDOwNuBLFdWYl7/2VsY6wO9vjNuFKQ+tiKyuFs8D6gnab5lL/ATmgYqzbc637AeDrsBukj8UeV5qvZg+GWpbfMCXe74csmE0vscWmzWKCTGrzrPmY2w3fmO/5F9gji9F4Cqjb0LUExkyq7kKHgkk7OBu37znM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b=xcGth7ra; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="xcGth7ra" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 6C613C2BCB8; Mon, 4 May 2026 08:50:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1777884604; bh=l7ehv2zbwR50zFLpHr+/piHe/PVXi5NUH6E/2RvgS+c=; h=Subject:To:Cc:From:Date:From; b=xcGth7raE16/fwqn/6c7DsZo1rCCf8Lgnq0awhxwwarD6cus/4bM182nHH7rk+7ik U4JS3ceMQaJheDhFn1coTcKItu9CWodda/gYiUcPHJVR29KPLbRmrxlvYnARv3XqBP GtLJ6z/6nxWWixVEzPRT6jEDjXZNWo+jw5E6f8ew= Subject: FAILED: patch "[PATCH] ceph: fix num_ops off-by-one when crypto allocation fails" failed to apply to 6.12-stable tree To: cfsworks@gmail.com,CFSworks@gmail.com,Slava.Dubeyko@ibm.com,idryomov@gmail.com Cc: From: Date: Mon, 04 May 2026 10:49:54 +0200 Message-ID: <2026050454-boundless-till-f646@gregkh> Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit The patch below does not apply to the 6.12-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-6.12.y git checkout FETCH_HEAD git cherry-pick -x a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842 # git commit -s git send-email --to '' --in-reply-to '2026050454-boundless-till-f646@gregkh' --subject-prefix 'PATCH 6.12.y' HEAD^.. Possible dependencies: thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From a0d9555bf9eaeba34fe6b6bb86f442fe08ba3842 Mon Sep 17 00:00:00 2001 From: Sam Edwards Date: Tue, 17 Mar 2026 19:37:33 -0700 Subject: [PATCH] ceph: fix num_ops off-by-one when crypto allocation fails 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 diff --git a/fs/ceph/addr.c b/fs/ceph/addr.c index 2090fc78529c..44553556ac74 100644 --- a/fs/ceph/addr.c +++ b/fs/ceph/addr.c @@ -1365,6 +1365,10 @@ void ceph_process_folio_batch(struct address_space *mapping, rc = move_dirty_folio_in_page_array(mapping, wbc, ceph_wbc, folio); 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;