As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - CREW REPORTED CABIN GRADUALLY FILLED WITH OIL FUMES AND SMOKE. AFT LAVATORY SMOKE DETECTORS ALSO BEGAN TO CHIME. EMERGENCY DECLARED FLIGHT RETURNED DFW LANDED WITHOUT INCIDENT. AIRCRAFT REMOVED FROM SERVICE. AIRCRAFT FERRIED TO AFW FOR REPAIRS. REPLACED PRIMARY AND SECONDARY HEAT EXCHANGERS AND AIR CYCLE MACHINE. SYSTEM GROUND CHECK NORMAL OPERATION.