As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
DURING CLIMB, FLIGHT ATTENDANT NOTICED SMOKE IN CABIN AND FORWARD LAV ALARM SOUNDED. FLIGHT CREW RETURNED AIRCRAFT TO DEPARTURE AIRPORT AND PERFORMED AN UNEVENTFUL LANDING. MAINTENANCE FOUND AN APU OIL LEAK. OIL LEAK WAS CORRECTED, CLEANED APU AREA, AND COMPLIED WITH PACK BURNOUT PROCEDURE. REPLACED COALESCER BAGS. OPERATIONAL CHECK OK.