Grease a 9 x 13 x 2 cake pan. Pour the cherry pie filling to cover the bottom of the pan. Use a spoon and cover cherry pie filling with crushed pineapple (evenly). Pour the powdered cake mix onto the cake and cover the pineapple evenly. Cut the margarine in small pieces and place pieces over the whole cake. Sprinkle the chopped nuts over the top. Bake at 350 degrees for 50 minutes. Test with a toothpick for doneness.