No luck. I added extra_ldflags = ["-lcudnn"] as you said but this time, it didn’t even add -lcudnn as an argument to nvcc when I built it.
When I did extra_compile_args={'nvcc': ['-lcudnn']} it did add -lcudnn as an argument but still had the error I showed above.
EDIT: I also just noticed this line at the top of the outputs when I build the extension:
UserWarning: Unknown Extension options: 'extra_ldflags'