I believe that the developers and maintainers of dma-buf have provided the needed signoff, both in person and in this thread. If there are any objections from that group, I'm happy to discuss any changes necessary to get this merged.
You need the permission of the owners of all the dependant code that forms the work. The rules and licence are quite clear, as I think are the views of several of the rights holders on both the interpretation and intent of the licensing of their code.
Please go and discuss estoppel, wilful infringement and re-licensing with your corporate attorneys. If you want to relicense components of the code then please take the matter up with the corporate attorneys of the rights holders concerned.
Alan