Calling kernel functions from BPF

Interesting news for me because I like BPF very much.
Now BPF programs can call bpf helpers, plus some limited set of kernel functions that were approved by kernel maintainers deliberately.

Like kprobe, the set of exported kernel functions won't be stable or guaranteed. As kernel version bumps up, the list of exported functions will change. Some functions would be added, deleted, renamed or parameters of functions would be modified. BPF developers would get stressed out if they depend on this feature. Because there are problems to maintain their own programs when they have to support different versions of kernel. But I think most bleeding edges have cumbersome disadvantages like this. So I would rather see positive side of this feature and try it out.