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.
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 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.