> Is the kernel simply too complex to reason about?

Yes it is. Not just the kernel, almost any application with more than a few thousand lines of code too. AI has humbled me so much I don’t believe humans have ever been able to fully understand and modify systems like that, we just did the best we could, wrote some tests and hoped for the best. If you use a language like C, as the kernel mostly does, then you’re really asking for vulnerabilities everywhere. Even Haskell code bases are buggy, languages just aren’t a panacea when it comes to writing reliable applications, but they at least make whole categories of bugs impossible by design, ignoring that is a crazy thing to do in 2026 with AI being able to scan your full code base in hours, it’s guaranteed to find exploits at will.