Depends on the uni—some CS departments will shove as much maths as they can at you and large numbers of people will fail purely because of that. Others will just churn out as many grads as they can and will require only the bare minimum in terms of maths. My uni's somewhere in the middle: first-year discrete maths and calc part 1 are compulsory, with calc part 2 and second-year discrete maths and cryptography highly recommended.
As for grinding, yeah I'd say that undergraduate level maths can be ground out, and as long as you don't fuck up the actual CS papers it's not like they're gonna kick you out or anything (my uni actually ran two calc part 1 courses per year so that people who failed would be able to repeat it that year without having to delay by repeating a first-year course in second year).