What does the swapping system do if it identifies the illegal page for swapping?

Question

So many times, we make foreground process to background process in linux system. How does it handle internally ?

Answer 1

If the disk block descriptor does not contain any record of the faulted page, then this causes the attempted memory reference is invalid and the kernel sends a “Segmentation violation” signal to the offending process. This happens when the swapping system identifies any invalid memory reference.