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* [PATCH 2/2 v2] nvme-rdma: fix controller reset hang during traffic
@ 2020-07-28  0:32 Sagi Grimberg
  2020-07-28  6:55 ` Christoph Hellwig
  2020-07-28 10:50 ` Christoph Hellwig
  0 siblings, 2 replies; 4+ messages in thread
From: Sagi Grimberg @ 2020-07-28  0:32 UTC (permalink / raw)
  To: linux-nvme, Christoph Hellwig, Keith Busch

commit fe35ec58f0d3 ("block: update hctx map when use multiple maps")
exposed an issue where we may hang trying to wait for queue freeze
during I/O. We call blk_mq_update_nr_hw_queues which in case of multiple
queue maps (which we have now for default/read/poll) is attempting to
freeze the queue. However we never started queue freeze when starting the
reset, which means that we have inflight pending requests that entered the
queue that we will not complete once the queue is quiesced.

So start a freeze before we quiesce the queue, and unfreeze the queue
after we successfully connected the I/O queues (and make sure to call
blk_mq_update_nr_hw_queues only after we are sure that the queue was
already frozen).

This follows to how the pci driver handles resets.

Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
---
Changes from v1:
- fix silly compilation errors

 drivers/nvme/host/rdma.c | 12 +++++++++---
 1 file changed, 9 insertions(+), 3 deletions(-)

diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
index 5c3848974ccb..44c76ffbb264 100644
--- a/drivers/nvme/host/rdma.c
+++ b/drivers/nvme/host/rdma.c
@@ -967,15 +967,20 @@ static int nvme_rdma_configure_io_queues(struct nvme_rdma_ctrl *ctrl, bool new)
 			ret = PTR_ERR(ctrl->ctrl.connect_q);
 			goto out_free_tag_set;
 		}
-	} else {
-		blk_mq_update_nr_hw_queues(&ctrl->tag_set,
-			ctrl->ctrl.queue_count - 1);
 	}
 
 	ret = nvme_rdma_start_io_queues(ctrl);
 	if (ret)
 		goto out_cleanup_connect_q;
 
+	if (!new) {
+		nvme_start_queues(&ctrl->ctrl);
+		nvme_wait_freeze(&ctrl->ctrl);
+		blk_mq_update_nr_hw_queues(ctrl->ctrl.tagset,
+			ctrl->ctrl.queue_count - 1);
+		nvme_unfreeze(&ctrl->ctrl);
+	}
+
 	return 0;
 
 out_cleanup_connect_q:
@@ -1008,6 +1013,7 @@ static void nvme_rdma_teardown_io_queues(struct nvme_rdma_ctrl *ctrl,
 		bool remove)
 {
 	if (ctrl->ctrl.queue_count > 1) {
+		nvme_start_freeze(&ctrl->ctrl);
 		nvme_stop_queues(&ctrl->ctrl);
 		nvme_rdma_stop_io_queues(ctrl);
 		if (ctrl->ctrl.tagset) {
-- 
2.25.1


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http://lists.infradead.org/mailman/listinfo/linux-nvme

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH 2/2 v2] nvme-rdma: fix controller reset hang during traffic
  2020-07-28  0:32 [PATCH 2/2 v2] nvme-rdma: fix controller reset hang during traffic Sagi Grimberg
@ 2020-07-28  6:55 ` Christoph Hellwig
  2020-07-28  7:10   ` Sagi Grimberg
  2020-07-28 10:50 ` Christoph Hellwig
  1 sibling, 1 reply; 4+ messages in thread
From: Christoph Hellwig @ 2020-07-28  6:55 UTC (permalink / raw)
  To: Sagi Grimberg; +Cc: Keith Busch, Christoph Hellwig, linux-nvme

Why is this a 2/2 v2, where is the 1/2?

On Mon, Jul 27, 2020 at 05:32:09PM -0700, Sagi Grimberg wrote:
> commit fe35ec58f0d3 ("block: update hctx map when use multiple maps")
> exposed an issue where we may hang trying to wait for queue freeze
> during I/O. We call blk_mq_update_nr_hw_queues which in case of multiple
> queue maps (which we have now for default/read/poll) is attempting to
> freeze the queue. However we never started queue freeze when starting the
> reset, which means that we have inflight pending requests that entered the
> queue that we will not complete once the queue is quiesced.
> 
> So start a freeze before we quiesce the queue, and unfreeze the queue
> after we successfully connected the I/O queues (and make sure to call
> blk_mq_update_nr_hw_queues only after we are sure that the queue was
> already frozen).
> 
> This follows to how the pci driver handles resets.
> 
> Signed-off-by: Sagi Grimberg <sagi@grimberg.me>
> ---
> Changes from v1:
> - fix silly compilation errors
> 
>  drivers/nvme/host/rdma.c | 12 +++++++++---
>  1 file changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/drivers/nvme/host/rdma.c b/drivers/nvme/host/rdma.c
> index 5c3848974ccb..44c76ffbb264 100644
> --- a/drivers/nvme/host/rdma.c
> +++ b/drivers/nvme/host/rdma.c
> @@ -967,15 +967,20 @@ static int nvme_rdma_configure_io_queues(struct nvme_rdma_ctrl *ctrl, bool new)
>  			ret = PTR_ERR(ctrl->ctrl.connect_q);
>  			goto out_free_tag_set;
>  		}
> -	} else {
> -		blk_mq_update_nr_hw_queues(&ctrl->tag_set,
> -			ctrl->ctrl.queue_count - 1);
>  	}
>  
>  	ret = nvme_rdma_start_io_queues(ctrl);
>  	if (ret)
>  		goto out_cleanup_connect_q;
>  
> +	if (!new) {
> +		nvme_start_queues(&ctrl->ctrl);
> +		nvme_wait_freeze(&ctrl->ctrl);
> +		blk_mq_update_nr_hw_queues(ctrl->ctrl.tagset,
> +			ctrl->ctrl.queue_count - 1);
> +		nvme_unfreeze(&ctrl->ctrl);
> +	}
> +
>  	return 0;
>  
>  out_cleanup_connect_q:
> @@ -1008,6 +1013,7 @@ static void nvme_rdma_teardown_io_queues(struct nvme_rdma_ctrl *ctrl,
>  		bool remove)
>  {
>  	if (ctrl->ctrl.queue_count > 1) {
> +		nvme_start_freeze(&ctrl->ctrl);
>  		nvme_stop_queues(&ctrl->ctrl);
>  		nvme_rdma_stop_io_queues(ctrl);
>  		if (ctrl->ctrl.tagset) {
> -- 
> 2.25.1
---end quoted text---

_______________________________________________
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Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH 2/2 v2] nvme-rdma: fix controller reset hang during traffic
  2020-07-28  6:55 ` Christoph Hellwig
@ 2020-07-28  7:10   ` Sagi Grimberg
  0 siblings, 0 replies; 4+ messages in thread
From: Sagi Grimberg @ 2020-07-28  7:10 UTC (permalink / raw)
  To: Christoph Hellwig; +Cc: Keith Busch, linux-nvme


> Why is this a 2/2 v2, where is the 1/2?

Sent on 7/24/20, 3:10 PM (PST)

Along with:
[PATCH 1/2] nvme-tcp: fix controller reset hang during traffic

_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

^ permalink raw reply	[flat|nested] 4+ messages in thread

* Re: [PATCH 2/2 v2] nvme-rdma: fix controller reset hang during traffic
  2020-07-28  0:32 [PATCH 2/2 v2] nvme-rdma: fix controller reset hang during traffic Sagi Grimberg
  2020-07-28  6:55 ` Christoph Hellwig
@ 2020-07-28 10:50 ` Christoph Hellwig
  1 sibling, 0 replies; 4+ messages in thread
From: Christoph Hellwig @ 2020-07-28 10:50 UTC (permalink / raw)
  To: Sagi Grimberg; +Cc: Keith Busch, Christoph Hellwig, linux-nvme

Applied to nvme-5.9 and added a fixes tag.

_______________________________________________
Linux-nvme mailing list
Linux-nvme@lists.infradead.org
http://lists.infradead.org/mailman/listinfo/linux-nvme

^ permalink raw reply	[flat|nested] 4+ messages in thread

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2020-07-28  0:32 [PATCH 2/2 v2] nvme-rdma: fix controller reset hang during traffic Sagi Grimberg
2020-07-28  6:55 ` Christoph Hellwig
2020-07-28  7:10   ` Sagi Grimberg
2020-07-28 10:50 ` Christoph Hellwig

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