The people of Ephraim did not force out all of the Canaanites living in Gezer. So the Canaanites continued to live in Gezer with the people of Ephraim.
This is the account of the forced labor Solomon used to build the Temple and the palace. He had them fill in the land and build the wall around Jerusalem. He also had them rebuild the cities of Hazor, Megiddo, and Gezer.
(In the past the king of Egypt had attacked and captured Gezer. After burning it, he killed the Canaanites who lived there. Then he gave it as a wedding present to his daughter, who married Solomon.
The Ephraimites could not force the Canaanites to leave Gezer, so the Canaanites still live among the Ephraimites today, but they became slaves of the Ephraimites.
The people of Zebulun did not force out the Canaanites living in the cities of Kitron and Nahalol. They stayed and lived with the people of Zebulun, but Zebulun made them work as slaves.