Let lockdep complain when locks are taken while waiting for userspace.

Hi guys,

because of the Vulkan graphics API we have a specialized synchronization object to handle both inter process as well as process to hardware synchronization.

The problem is now that when drivers call this interface with some lock help it is trivial to create a deadlock when those locks are also needed in a page fault for example.

The idea of this patch is now to let lockdep complain when any locks are called when the interface is used.

Please review and/or comment.

Thanks, Christian.