Jets Geno Smith -- Punched Out in Locker Room Fight ... Out 6-8 Weeks

Jets QB Geno Smith got punched in the face so hard by a teammate ... he broke his jaw, and will miss several weeks of the season.

The player who busted Geno's jaw is 2nd year linebacker Ikemefuna Enemkpali -- and the Jets have already cut his ass over the locker room fight.

Jets officials say Geno will be out for 6-10 weeks healing his jaw.

Enemkpali was basically a bench jockey. The 6'1" 260 lbs backup linebacker had a grand total of 3 tackles last season ... so, it's not like he'll be missed.

Smith, on the other hand, was in competition for the starting job. He posted a pic -- his face doesn't look all that swollen -- and promised "I'll be back."