As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
CREW RECEIVED EICAS TOILET SMOKE INDICATION ALONG WITH VISIBLE SMOKE IN AFT CABIN AND LAVATORY QRH FOLLOWED UNEVENTFUL UNSCHEDULED RETURN TO AIRPORT. PERFORMED ENGINE RUNS AND OPERATIONAL CHECKS OF BLEED AIR SYSTEM WITH NO DEFECTS NOTED.