Re: [PATCH 5/5] nvme-fabrics: clear the poll map if no poll queues are mapped

[Hannes Reinecke <hare@suse.de>]

On 10/14/26 9:46 AM, Daniel Wagner wrote:
> From: Daniel Wagner <wagi@kernel.org>
> 
> blk_mq_alloc_tag_set sets the nr_queues of every map to nr_hw_queues.
> When nr_poll_queues is set but no queues are left for polling,
> nvmf_map_queues skips the poll map and leaves it this way, with all CPUs
> mapped to hctx 0.  The queue then claims poll support, polled I/O ends
> up on hctx 0, which isn't a poll queue, and hctx 0 is marked as a poll
> hctx, so even the Connect command of the first I/O queue is marked as
> polled.
> 
> Clear the poll map when no poll queues are mapped, so polled I/O is
> rejected with -EOPNOTSUPP.
> 
> Fixes: 1a9460cef571 ("nvme-tcp: support simple polling")
> Fixes: 5651cd3c4336 ("nvme-rdma: fix queue mapping when queue count is limited")
> Signed-off-by: Daniel Wagner <wagi@kernel.org>
> ---
>   drivers/nvme/host/fabrics.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/nvme/host/fabrics.c b/drivers/nvme/host/fabrics.c
> index 27a8ce51d2b3..3d7ad86c1955 100644
> --- a/drivers/nvme/host/fabrics.c
> +++ b/drivers/nvme/host/fabrics.c
> @@ -1199,6 +1199,13 @@ void nvmf_map_queues(struct blk_mq_tag_set *set, struct nvme_ctrl *ctrl,
>   			io_queues[HCTX_TYPE_DEFAULT] +
>   			io_queues[HCTX_TYPE_READ];
>   		blk_mq_map_queues(&set->map[HCTX_TYPE_POLL]);
> +	} else {
> +		/*
> +		 * blk_mq_alloc_tag_set sets nr_queues of all maps to
> +		 * nr_hw_queues.  Clear the poll map, otherwise the queue claims
> +		 * poll support and polled I/O ends up on hctx 0.
> +		 */
> +		set->map[HCTX_TYPE_POLL].nr_queues = 0;
>   	}
>   
>   	dev_info(ctrl->device,
> 
Reviewed-by: Hannes Reinecke <hare@kernel.org>

Cheers,

Hannes
-- 
Dr. Hannes Reinecke                  Kernel Storage Architect
hare@suse.de                                +49 911 74053 688
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