An Air Canada Boeing 777-300, registration C-FIUL performing flight AC-27 from Toronto,ON (Canada) to Shanghai Pudong (China) with 388 passengers and 17 crew, was enroute at FL320 near Fairbanks,AK (USA) when smoke was observed in the cabin. The crew worked the related checklists and suspected the recirculation fans as source of the smoke, the recirculation fans were shut down and the smoke and smell dissipated. The aircraft continued the flight to Shanghai for a safe landing about 8.5 hours later. The Canadian TSB reported maintenance replaced the lower left and right recirculation fans, an operational check was successful.