On Wed, Nov 28, 2018 at 08:58:00AM -0700, Jens Axboe wrote:

On 11/28/18 8:49 AM, Keith Busch wrote:

quoted

On Wed, Nov 28, 2018 at 11:08:48AM +0100, Christoph Hellwig wrote:

quoted

On Wed, Nov 28, 2018 at 06:07:01PM +0800, Ming Lei wrote:

quoted

quoted

Is this the nvme target on top of null_blk?

Yes.

And it goes away if you revert just the last patch?

It looks like a problem existed before that last patch. Reverting it
helps only if the request happened to have not been reallocated. If it
had been reallocated, the NULL_IRQ_TIMER would have completed the wrong
request out-of-order. If this were a real device, that'd probably result
in data corruption.

null_blk just needs updating for this.

Isn't this the nvme target's problem? It shouldn't complete requests
dispatched to its backing device, so I'm thinking something like the
following is what should happen. Untested at the moment, but will try
it out shortly.

---

diff --git a/drivers/nvme/target/loop.c b/drivers/nvme/target/loop.c
index 9908082b32c4..116398b240e5 100644
--- a/drivers/nvme/target/loop.c
+++ b/drivers/nvme/target/loop.c

@@ -428,10 +428,14 @@ static int nvme_loop_configure_admin_queue(struct nvme_loop_ctrl *ctrl)
 static void nvme_loop_shutdown_ctrl(struct nvme_loop_ctrl *ctrl)
 {
 	if (ctrl->ctrl.queue_count > 1) {
-		nvme_stop_queues(&ctrl->ctrl);
-		blk_mq_tagset_busy_iter(&ctrl->tag_set,
-					nvme_cancel_request, &ctrl->ctrl);
+		/*
+		 * The back end device driver is responsible for completing all
+		 * entered requests
+		 */
+		nvme_start_freeze(&ctrl->ctrl);
+		nvme_wait_freeze(&ctrl->ctrl);
 		nvme_loop_destroy_io_queues(ctrl);
+		nvme_unfreeze(&ctrl->ctrl);
 	}
 
 	if (ctrl->ctrl.state == NVME_CTRL_LIVE)

---