The terror famine in the Ukraine, which killed somewhere around 10 million, was engineered in 1932-33, long before Hitler was an issue. Stalin did it as a "Final Solution" to rebellious Ukrainians who were resisting forced collectivization. There was an earlier deliberate famine in 1921-22 which killed almost 2 million.
Stalin did not need Hitler to provide an excuse for mass killings. He did just fine long before Adolf came on the scene.
The killings after WW2 were relatively minor, and concerned purges of the Communist Party itself. Some Communists were more upset about these latter purges because they happened to affect their own, rather than unimportant peasants