Re: [PATCH v3 2/2] workqueue: Add warnings and ensure one among WQ_PERCPU or WQ_UNBOUND is present

[Tejun Heo]

On Thu, May 28, 2026 at 06:01:59PM +0200, Marco Crivellari wrote:
...
> @@ -5850,6 +5850,23 @@ static struct workqueue_struct *__alloc_workqueue(const char *fmt,
>  		pr_warn_once("workqueue: name exceeds WQ_NAME_LEN. Truncating to: %s\n",
>  			     wq->name);
>  
> +	/*
> +	 * One among WQ_PERCPU and WQ_UNBOUND must be set, but not both.
> +	 * - If neither is set, default to WQ_PERCPU
> +	 * - If both are set, default to WQ_UNBOUND
> +	 *
> +	 * This code can be removed after workqueue are unbound by default
> +	 */
> +	if (!(flags & (WQ_UNBOUND | WQ_PERCPU))) {
> +		pr_warn_ratelimited("workqueue: %s is using neither WQ_PERCPU or WQ_UNBOUND. "
> +			"Setting WQ_PERCPU.\n", wq->name);
> +		flags |= WQ_PERCPU;
> +	} else if((flags & WQ_PERCPU) && (flags & WQ_UNBOUND)) {
> +		pr_warn_ratelimited("workqueue: %s uses both WQ_PERCPU and WQ_UNBOUND. "
> +			"Dropped WQ_PERCPU, keeping WQ_UNBOUND.\n", wq->name);
> +		flags &= (~WQ_PERCPU);
> +	}

Let's just WARN_ONCE() on these. These are outright bugs, right?

Thanks.

-- 
tejun