Hi Sasha, if you take this one, you'll need the fix for it:
c260121a97a3 ("NFS: Fix a double unlock from nfs_match,get_client")
I didn't see this fix go through my inbox for your stable tree, so apologies if maybe I missed it.
Looks like you are also applying this one to 4.19 and 4.14, -- I'll just reply once here.