I did find some links to some of my old posts on restartable sequences for user space rcu. Looked into using unix signal handling but it was pretty problematic to put it mildly. Definitely something you had to implement in the kernel.

https://groups.google.com/g/comp.os.linux.development.system... https://groups.google.com/g/comp.programming.threads/c/bq61m... https://groups.google.com/g/comp.programming.threads/c/muhN3...