As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
IMMEDIATELY AFTER TAKEOFF, SMOKE WAS REPORTED IN THE CABIN AREA AND LAV SMOKE DETECTORS WERE IN ALARM. CREW COMPLIED WITH COM, DONNED OXYGEN MASKS, & RETURNED TO AN UNEVENTFUL LANDING AT GFK. SMOKE HAD DISSIPATED BEFORE LANDING & THERE WAS NO EVIDENCE OF ANY FIRE. MAINTENANCE FOUND THE LT ACM DUMPING OIL & CAUSING SMOKE IN CABIN. THE LT ACM WAS MEL'D & BOTH WATER SEPARATOR BAGS WERE REPLACED. A/C RETURNED TO SERVICE.