As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DFW - FLT 0311 - DURING CRUISE EN ROUTE DFW-PDX SMOKE IN CABIN, AIR INTERRUPTED BACK TO DFW AND LANDED OVERWEIGHT WITHOUT INCIDENT. NR 2 AIR CYCLE MACHINE OVERSERVICED. SERVICED TO PROPER LEVEL, PRECAUTIONARY REPLACED BOTH WATER SEPARATOR PACKS. SYSTEM GROUND CHECKED NORMAL OPERATION. ACCOMPLISHED FCF, NO SMOKE NOTED AND SYSTEM CHECKED NORMAL OPERATION. (W)