(because the kernel typically allocates blocks of about 32 bytes long, and swapping happens once every 4096 bytes. so each allocation has less than 1% chance of triggering a nested exception, and perhaps not all of those cause issues. and most kernel allocation happens before userspace code runs so there are no exception registers to mess up.)
Mastodon is a server for a federated social network: everyone can run a server if they want to, including me. So this is a Mastodon server for me (Vierkantor) and my friends.