From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753386AbcAETrr (ORCPT ); Tue, 5 Jan 2016 14:47:47 -0500 Received: from youngberry.canonical.com ([91.189.89.112]:44869 "EHLO youngberry.canonical.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753001AbcAETrE (ORCPT ); Tue, 5 Jan 2016 14:47:04 -0500 From: Kamal Mostafa To: linux-kernel@vger.kernel.org, stable@vger.kernel.org, kernel-team@lists.ubuntu.com Cc: Mikulas Patocka , Mike Snitzer , Kamal Mostafa Subject: [PATCH 4.2.y-ckt 067/211] dm: initialize non-blk-mq queue data before queue is used Date: Tue, 5 Jan 2016 11:42:55 -0800 Message-Id: <1452023119-25647-68-git-send-email-kamal@canonical.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1452023119-25647-1-git-send-email-kamal@canonical.com> References: <1452023119-25647-1-git-send-email-kamal@canonical.com> X-Extended-Stable: 4.2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.2.8-ckt1 -stable review patch. If anyone has any objections, please let me know. ------------------ From: Mikulas Patocka commit ad5f498f610fa3fd8bd265139098bc1405cd2783 upstream. Commit bfebd1cdb497a57757c83f5fbf1a29931591e2a4 ("dm: add full blk-mq support to request-based DM") moves the initialization of the fields backing_dev_info.congested_fn, backing_dev_info.congested_data and queuedata from the function dm_init_md_queue (that is called when the device is created) to dm_init_old_md_queue (that is called after the device type is determined). There is no locking when accessing these variables, thus it is possible for other parts of the kernel to briefly see this data in a transient state (e.g. queue->backing_dev_info.congested_fn initialized and md->queue->backing_dev_info.congested_data uninitialized, resulting in passing an incorrect parameter to the function dm_any_congested). This queue data is left initialized for blk-mq devices even though they that don't use it. Fixes: bfebd1cdb497 ("dm: add full blk-mq support to request-based DM") Signed-off-by: Mikulas Patocka Signed-off-by: Mike Snitzer Signed-off-by: Kamal Mostafa --- drivers/md/dm.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff --git a/drivers/md/dm.c b/drivers/md/dm.c index 3e32f4e..e0bf361 100644 --- a/drivers/md/dm.c +++ b/drivers/md/dm.c @@ -2251,6 +2251,13 @@ static void dm_init_md_queue(struct mapped_device *md) * This queue is new, so no concurrency on the queue_flags. */ queue_flag_clear_unlocked(QUEUE_FLAG_STACKABLE, md->queue); + + /* + * Initialize data that will only be used by a non-blk-mq DM queue + * - must do so here (in alloc_dev callchain) before queue is used + */ + md->queue->queuedata = md; + md->queue->backing_dev_info.congested_data = md; } static void dm_init_old_md_queue(struct mapped_device *md) @@ -2261,10 +2268,7 @@ static void dm_init_old_md_queue(struct mapped_device *md) /* * Initialize aspects of queue that aren't relevant for blk-mq */ - md->queue->queuedata = md; md->queue->backing_dev_info.congested_fn = dm_any_congested; - md->queue->backing_dev_info.congested_data = md; - blk_queue_bounce_limit(md->queue, BLK_BOUNCE_ANY); } -- 1.9.1