[PATCH 1/1] nvme: correctly account for namespace head reference counter

[Daniel Wagner]

Hi Nilay,

On Fri, Jun 20, 2025 at 01:32:43PM +0530, Nilay Shroff wrote:
> --- a/drivers/nvme/host/core.c
> +++ b/drivers/nvme/host/core.c
> @@ -4089,6 +4089,7 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info)
>  	struct nvme_ns *ns;
>  	struct gendisk *disk;
>  	int node = ctrl->numa_node;
> +	bool last_path = false;
>  
>  	ns = kzalloc_node(sizeof(*ns), GFP_KERNEL, node);
>  	if (!ns)
> @@ -4181,9 +4182,13 @@ static void nvme_alloc_ns(struct nvme_ctrl *ctrl, struct nvme_ns_info *info)
>   out_unlink_ns:
>  	mutex_lock(&ctrl->subsys->lock);
>  	list_del_rcu(&ns->siblings);
> -	if (list_empty(&ns->head->list))
> +	if (list_empty(&ns->head->list)) {
>  		list_del_init(&ns->head->entry);
> +		last_path = true;
> +	}
>  	mutex_unlock(&ctrl->subsys->lock);
> +	if (last_path)
> +		nvme_put_ns_head(ns->head);
>  	nvme_put_ns_head(ns->head);

Could the put moved in front of 'goto out_unlink_ns'?

Thanks,
Daniel