In investigating the MT-fork deadlock stuff and working on a patch that makes it attempt to trap rather than deadlocking, I found a problem with interaction of fork and aio. A fix for that, along with the patch to trap, and a minimal testcase for the aio bug, are attached. There's also a problematic interaction of abort with fork that was just found in glibc that also exists in musl, that I still need to fix. I'll follow up later with a proposed solution for that. Rich