From Stephen's reply and comment at https://unix.stackexchange.com/a/289446/674in some cases, data which has been marked for paging out but hasn't  yet been paged out.paging out would indeed involve accessing the disk, but that's another  operation which doesn't have anything to do with the page fault:  there's a marking operation, a separate paging out operation (which  hasn't happened yet), and the page fault which causes the memory to  be retrieved (so the page-out probably won't happen at all). Even in  (3), servicing the page fault doesn't involve touching the disk  (the data isn't there yet), so it's a minor page fault.What does the page fault which causes the memory to be retrieved (so the page-out probably won't happen at all) mean ?Why won't the page-out probably happen at all?Why servicing the page fault doesn't involve touching the disk?Is the reason for not paging-out yet in data which has been marked for paging out but hasn't yet been paged out that the data needed isn't on the disk yet?Thanks.
Questions about minor page fault
linux;virtual memory