I'd just typed: sudo kill -TERM -1490947 And instantly all services went down. Maybe my code had a signal handling bug. Maybe I don't understand Unix as well as I think I do.
As it turned out, the outage was caused by a bug in kill(1). The kill program is 50 years old. Its spec is simple and stable.
It's probably exercised a billion times a day. A bug in kill was so surprising that, once I'd found it, I couldn't stop there. I needed to know how this bug came to be, and what had led the programmers so badly astray.
When I eventually found the root cause, there was an even bigger surprise. It had led to not just one bug, but a whole series of kill bugs that shipped in Ubuntu 14, 16, 18, 22 and 24 LTS.
