You could say that about most bugs...

FreeBSD doesn't have a per-thread cache, but does similarly use a generation number to allow operations to detect stale state upon reacquiring the vm map lock. I don't see why it isn't prone to the same kinds of bugs.

I entirely disagree. You have have the most well thought out, architected, designed system in the world with:

if (i=0) {

You could argue that a system written in a language that permits such errors is not well-thought out. The terms you're using are not well-defined, so it's easy to disagree endlessly without arriving at a useful insight.