I don't know about any rioting, but some Inter fans got onto the pitch during the match, and others started to burn their banners in protest of the performance.
There might be some rioting going on Moratti's office right now, though, with Tardelli probably on the receiving end.
Being beaten 6-0 in a match is humiliating, being beaten in the derby is humiliating, but being beaten 6-0 in the derby? I don't know how Tardelli would be able to survive that. Not with some of the performances he and Inter have put in this season.