FAILED: patch "[PATCH] blk-mq: move cancel of requeue_work to the front of" failed to apply to 4.19-stable tree

The patch below does not apply to the 4.19-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 <[email protected]>.

thanks,

greg k-h

------------------ original commit in Linus's tree ------------------

From e26cc08265dda37d2acc8394604f220ef412299d Mon Sep 17 00:00:00 2001
From: zhengbin <[email protected]>
Date: Mon, 12 Aug 2019 20:36:55 +0800
Subject: [PATCH] blk-mq: move cancel of requeue_work to the front of
blk_exit_queue

blk_exit_queue will free elevator_data, while blk_mq_requeue_work will access it. Move cancel of requeue_work to the front of blk_exit_queue to avoid use-after-free.

blk_exit_queue blk_mq_requeue_work
__elevator_exit blk_mq_run_hw_queues
blk_mq_exit_sched blk_mq_run_hw_queue
dd_exit_queue blk_mq_hctx_has_pending
kfree(elevator_data) blk_mq_sched_has_work
dd_has_work

index f78d3287dd82..a8e6a58f5f28 100644
@@ -2666,8 +2666,6 @@ void blk_mq_release(struct request_queue *q)
 	struct blk_mq_hw_ctx *hctx, *next;
 	int i;
 
-	cancel_delayed_work_sync(&q->requeue_work);
-
 	queue_for_each_hw_ctx(q, hctx, i)
 		WARN_ON_ONCE(hctx && list_empty(&hctx->hctx_list));
 

index 977c659dcd18..9bfa3ea4ed63 100644
@@ -892,6 +892,9 @@ static void __blk_release_queue(struct work_struct *work)
 
 	blk_free_queue_stats(q->stats);
 
+	if (queue_is_mq(q))
+		cancel_delayed_work_sync(&q->requeue_work);
+
 	blk_exit_queue(q);
 
 	blk_queue_free_zone_bitmaps(q);