成唯識論演祕 6.657

6.657

釋曰：二無常者，一生位苦，謂苦苦；二滅位苦，謂壞苦，生、滅二位皆無常攝，名二無常。

The explanation says: The two impermanences are: first, the suffering of the state of arising, namely the suffering of suffering; second, the suffering of the state of cessation, namely the suffering of change. Both the states of arising and cessation are subsumed under impermanence, and are called the two impermanences.