As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
SMOKE SMELL IN AFT AREA OF CABIN REPORTED BY A PASSENGER AND LEFT LAV SMOKE DETECTOR ALARM SOUNDED ON TAXI OUT. AIRCRAFT RETURNED TO GATE. NUMBER TWO ENGINE FOUND OVER SERVICED BY TWO QUARTS ON THE ENGINE OIL. ENGINE OIL SERVICED TO NORMAL LEVEL. ENGINE GROUND RUN PERFORMED AND BLEED AIR CHECK GOOD.