Re: [PATCH 2/2] blk-mq: convert WARN_ON in __blk_mq_run_hw_queue to printk

Christian Borntraeger
2018-01-17T16:05:46Z

On 01/17/2018 04:46 PM, Jens Axboe wrote:
> On 1/17/18 5:34 AM, Ming Lei wrote:
>> We know this WARN_ON is harmless and the stack trace isn't useful too,
>> so convert it to printk(), and avoid to confuse people.
>
> I disagree, it is useful to know the exact path it happened from,
> in case it's a valid warning. It could be an inline run and
> we screwed up the logic, or it could be from a workqueue and
> the reason would be entirely different.

Then add a dump_stack or whatever, but WARN_ON does have fatal effects
for some setups. If it can happen then WARN_ON is just wrong.