The feedback set problem with respect to the terminals S. We call it the subset feedback set problem.
The cycle packing problem with respect to the terminals S, i.e., each cycle has to contain a vertex in S (such a cycle is called an S-cycle). We call it the S-cycle packing problem.
For fixed k, we can either find a vertex set X of size k such that has no S-cycle, or conclude that such a vertex set does not exist in time, where n is the number of vertices of the input graph and m is the number of edges of the input graph.
For fixed k, we can either find k vertex-disjoint S-cycles or conclude that such k disjoint cycles do not exist in time.