Specifically, the weak spot is in “maple tree,” a new data structure system for VMAs introduced in Linux kernel 6.1 that replaced the “red-black trees” and relied on the read-copy-update (RCU) mechanism.

Maple Tree also recently caused intermittent failures in some of my CPU-intensive tasks, in such an obscure way that I only found out by dumb luck that it was a kernel bug. I expect it will be great eventually, but it’s feeling pretty rough at the moment. I’m thinking this code should have had more testing and maturing before going mainline.

People who can find such bugs have always amazed me. The understanding of the kernel required seems so impossibly vast.