he would be stuck in a cylindrical tube of portal matter repeated infinatley. as he would be going through one portal into another than into the first again and again and again etc. probs make a pic of this later :)

You would crush yourself.

The troll will flip for each portal at ludicrous speed before he gets crushed, and when he does the remainns will keep flipping between portals, but because of lack of space it would just be changing the direction they are facing.