I have some multithreaded code where the threads spend a significant amount time in the page fault handler of the kernel (Linux 5.4). But this only happens on a two Socket NUMA machine, but not on on a machine without NUMA. So my question is, can an access to NUMA memory trigger page faults? I also made sure that all memory was initialized before multithreading (by the main thread), so I would have expected no page faults at all in the other threads.

I know that this is not optimal code for NUMA machines and I know how I could improve it, but I want to understand what happens here.