I also run a public cgit instance and get over 1M hits every day, although my pet projects are nowhere near the size or impact of kernel. I had to block (via nginx conf) cgit endpoints for diffs, blame, snapshots and historical commits, because nothing else works. Now they return 402 (payment required). I consider this my total defeat and it's killing me inside, but it is what it is.

You could also publish a list of IP addresses.