Patch "nvme: use blk_mq_start_hw_queues() in nvme_kill_queues()" has been added to the 4.9-stable tree

This is a note to let you know that I've just added the patch titled

nvme: use blk_mq_start_hw_queues() in nvme_kill_queues()

to the 4.9-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
nvme-use-blk_mq_start_hw_queues-in-nvme_kill_queues.patch
and it can be found in the queue-4.9 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree, please let <[email protected]> know about it.

From: Ming Lei <[email protected]>
Date: Mon, 22 May 2017 23:05:03 +0800
Subject: nvme: use blk_mq_start_hw_queues() in nvme_kill_queues()

From: Ming Lei <[email protected]>

commit 806f026f9b901eaf1a6baeb48b5da18d6a4f818e upstream.

Inside nvme_kill_queues(), we have to start hw queues for draining requests in sw queues, .dispatch list and requeue list, so use blk_mq_start_hw_queues() instead of blk_mq_start_stopped_hw_queues() which only run queues if queues are stopped, but the queues may have been started already, for example nvme_start_queues() is called in reset work function.

blk_mq_start_hw_queues() run hw queues in current context, instead of running asynchronously like before. Given nvme_kill_queues() is run from either remove context or reset worker context, both are fine to run hw queue directly. And the mutex of namespaces_mutex isn't a problem too becasue nvme_start_freeze() runs hw queue in this way already.

---
 drivers/nvme/host/core.c |    8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

@@ -2049,7 +2049,13 @@ void nvme_kill_queues(struct nvme_ctrl *
 		revalidate_disk(ns->disk);
 		blk_set_queue_dying(ns->queue);
 		blk_mq_abort_requeue_list(ns->queue);
-		blk_mq_start_stopped_hw_queues(ns->queue, true);
+
+		/*
+		 * Forcibly start all queues to avoid having stuck requests.
+		 * Note that we must ensure the queues are not stopped
+		 * when the final removal happens.
+		 */
+		blk_mq_start_hw_queues(ns->queue);
 	}
 	mutex_unlock(&ctrl->namespaces_mutex);
 }

Patches currently in stable-queue which might be from [email protected] are

queue-4.9/nvme-use-blk_mq_start_hw_queues-in-nvme_kill_queues.patch queue-4.9/nvme-avoid-to-use-blk_mq_abort_requeue_list.patch