Huge pages are an absolutely great idea. I will continue to complain about our eternal commitment to 4k pages, with all their pitfalls, which it appears we may

Huge pages are an absolutely great idea. I will continue to complain about our eternal commitment to 4k pages, with all their pitfalls, which it appears we may be stuck with until the heat death of the universe. At the very minimum we could go to 16k pages, which are good for many reasons including, in particular, being able to have bigger VIPT cache sizes without needing an increase in associativity (and thus latency). Not the end of the world but a very solid win on top of the TLB wins. But transparent hugepages continue to be a massive source of bugs, weird behaviors, and total system failures in my experience. I just got a bug report this week where a simple THP enabled system simply spun out of control with a kernel task locking the system at 100% CPU for minutes, with a 10 line reproducer via mmap(2). This is in combination with qemu/libvirt in a virtual machine, and it's possible the virtualization stack is just exposing bugs, but, like. This is very well tested stuff! I'm not sure "Google enabled it fleet wide, so it can be done" is very re-assuring to me when most of us don't have fleetops/infra/kernel teams capable of dealing with this stuff. The person who reported this bug said they started seeing odd behavior a month ago, before boiling it down; it wasn't readily apparent at all. Is this just a massive footgun for our distro users? I dunno. Something that works in the p95 and then collapses horrifically in the p99 cases like this doesn't feel great. I try not to be superstitious about things like this but, yeah. It's weird. Anyway. This reminds me I have to submit some patches to disable jemalloc in a few aarch64 packages so I can use them on Asahi Linux. 4k pages will haunt us until the end of time.