linux-kernel - [PATCH 2/2 v5.10] dm rq: don't queue request to blk-mq during DM suspend

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Message-Id: <20250811052702.145189-3-shivani.agarwal@broadcom.com>
Date: Sun, 10 Aug 2025 22:27:02 -0700
From: Shivani Agarwal <shivani.agarwal@...adcom.com>
To: stable@...r.kernel.org,
	gregkh@...uxfoundation.org
Cc: bcm-kernel-feedback-list@...adcom.com,
	linux-kernel@...r.kernel.org,
	ajay.kaher@...adcom.com,
	alexey.makhalov@...adcom.com,
	tapas.kundu@...adcom.com,
	agk@...hat.com,
	snitzer@...nel.org,
	mpatocka@...hat.com,
	dm-devel@...ts.linux.dev,
	Ming Lei <ming.lei@...hat.com>,
	Mike Snitzer <snitzer@...hat.com>,
	Shivani Agarwal <shivani.agarwal@...adcom.com>
Subject: [PATCH 2/2 v5.10] dm rq: don't queue request to blk-mq during DM suspend

From: Ming Lei <ming.lei@...hat.com>

commit b4459b11e84092658fa195a2587aff3b9637f0e7 upstream.

DM uses blk-mq's quiesce/unquiesce to stop/start device mapper queue.

But blk-mq's unquiesce may come from outside events, such as elevator
switch, updating nr_requests or others, and request may come during
suspend, so simply ask for blk-mq to requeue it.

Fixes one kernel panic issue when running updating nr_requests and
dm-mpath suspend/resume stress test.

Cc: stable@...r.kernel.org
Signed-off-by: Ming Lei <ming.lei@...hat.com>
Signed-off-by: Mike Snitzer <snitzer@...hat.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>
[Shivani: Modified to apply on 5.10.y]
Signed-off-by: Shivani Agarwal <shivani.agarwal@...adcom.com>
---
 drivers/md/dm-rq.c | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/drivers/md/dm-rq.c b/drivers/md/dm-rq.c
index 7762bde40963..a6ea77432e34 100644
--- a/drivers/md/dm-rq.c
+++ b/drivers/md/dm-rq.c
@@ -490,6 +490,14 @@ static blk_status_t dm_mq_queue_rq(struct blk_mq_hw_ctx *hctx,
 	struct mapped_device *md = tio->md;
 	struct dm_target *ti = md->immutable_target;
 
+	/*
+	 * blk-mq's unquiesce may come from outside events, such as
+	 * elevator switch, updating nr_requests or others, and request may
+	 * come during suspend, so simply ask for blk-mq to requeue it.
+	 */
+	if (unlikely(test_bit(DMF_BLOCK_IO_FOR_SUSPEND, &md->flags)))
+		return BLK_STS_RESOURCE;
+
 	if (unlikely(!ti)) {
 		int srcu_idx;
 		struct dm_table *map;
-- 
2.40.4