Place potatoes in a saucepan; cover with water. Bring to a boil. Reduce heat, and simmer 10 minutes or until potatoes are almost tender. Add corn to pan; cook 5 minutes or until potatoes are tender. Drain well. Place potato mixture in a large bowl, and mash potato mixture with a potato masher.
Combine coconut milk, oil, and butter in a small saucepan; bring to a boil. Stir milk mixture, curry, salt, and turmeric into potato mixture.