As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CAPTAIN CALLED-ADVISED THEY HAD AN AMBER CAUTION SMOKE IN THE LAVATORY. FLT ATTENDANT ADVISED SMOKE ALARM WAS GOING OFF AND THERE WAS A FIRE ODOR. FLIGHT RETURNED TO MSP BUT WHILE ON THE APPROACH CAUTION AND ALARM WENT OFF. FLIGHT DID NOT DECLARE AN EMERGENCY BUT DID LAND OVERWEIGHT.