Soft faults - when the page is in RAM but not loaded into the process or mapped to the process’ address space.
- Cases:
fork()and copy-on-write- the child touches a page for the first time → OS gives it a copy → soft fault
- page was already in RAM but not in child’s address space
mmap(), if another process has read into a file, it’s in memory but not in the current address space
Hard faults - when the page is in disk and not in memory yet.