For example, if one process maps the first 8KB of a 1MB sized file, the VM system may choose a free 8KB physical frame for the mapping. There are no particular alignment requirements on this 8KB physical page. If a second process then requests say a 1M mapping to the same file, then the second mapping cannot be done using a large page size because the VM system already allocated an unaligned SIC page for the first mapping. Even if the 8K page was aligned correctly on a 1MB boundary, the rest of the physical memory after the 8KB page may not be free.