Context information in memory-allocation requests

Actually, in principle there's no difference between passing the flag up the call chain or setting it in the task struct – you need to check all caller chains in both cases.

The advantages of a per-task flag are that (a) you don't need the stupid function parameter everywhere, resulting in a (very small) speed-up and somewhat more readable code, and (b) you don't miss calls where it'd be reqired.