As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB OF FLIGHT 7332 CREW RECEIVED A LAVATORY SMOKE MESSAGE AND CONFIRMED SMOKE WAS PRESENT IN THE CABIN. CREW RETURNED TO FIELD AND PASSENGERS DEPLANED THROUGH NORMAL DOOR ON TAXIWAY. THE SMOKE WAS FOUND TO BE CAUSED BY APU OIL OVER SERVICING CAUSING THE COALESCER BAGS TO BECOME OIL SOAKED THUS CREATING THE SMOKE IN THE CABIN. THE OIL LEVEL WAS CORRECTED AND COALESCER BAGS WERE REPLACED. A SATISFACTORY OPERATIONAL CHECK WAS PERFORMED AND AIRCRAFT WAS RETURNED TO SERVICE.