Preheat the oven to 375 degrees F (190 degrees C). Sift together the flour, baking soda, salt and cinnamon; stir in the oats and set aside. Grease cookie sheets.
In a large bowl, cream together the butter, white sugar and brown sugar until light. Beat in the eggs, one at a time, then stir in the vanilla. Stir in the flour mixture alternately with the buttermilk. Fold in the raisins and walnuts. Drop by rounded spoonfuls onto the prepared cookie sheets.
Bake for 8 to 10 minutes in the preheated oven, until lightly browned. Allow cookies to cool on baking sheet for 5 minutes before removing to a wire rack to cool completely.
