As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW FLIGHT ATTENDANTS REPORTED VISIBLE VAPOR & SMOKE IN AFT PART OF CABIN. EMERGENCY DECLARED FLIGHT RETURNED DFW LANDED WITHOUT INCIDENT. ACFT REMOVED FROM SERVICE. REPLACED APU & TEMPERATURE CONTROL VLV ON LT PACK. SYS GND CHECKED NORMAL, OPERATION CLOSED.