Hole in my ship

Last days few guys, who plays against me with white pieces, made hole in my opening repertoire.

After moves

1.d4 d5 2.Nf3 Nf6 3.e3 e6 4.c4 c6 5.Nc3 Nbd7 6.Qc2 Bd6

they played 7.g2-g4.

 What the correct answer to this mess, tell me who knows?