Re: [PATCH 3/5] mm, notifier: Catch sleeping/blocking for !blockable

Jason Gunthorpe
2019-08-15T00:00:29Z

On Wed, Aug 14, 2019 at 10:20:25PM +0200, Daniel Vetter wrote:
> We need to make sure implementations don't cheat and don't have a
> possible schedule/blocking point deeply burried where review can't
> catch it.
>
> I'm not sure whether this is the best way to make sure all the
> might_sleep() callsites trigger, and it's a bit ugly in the code flow.
> But it gets the job done.
>
> Inspired by an i915 patch series which did exactly that, because the
> rules haven't been entirely clear to us.

I thought lockdep already was able to detect:

spin_lock()
might_sleep();
spin_unlock()

Am I mistaken? If yes, couldn't this patch just inject a dummy lockdep
spinlock?

Jason