SIGSEGV This!

As we saw, some (lots of) the virtual memory sections of a process are not mapped to physical memory. While some of them are just paged out, others are never allocated.

As the process needs more memory, the system allocates more pages for it, and the virtual memory table of the process - grows.

If a process tries to access a virtual memory page that was not allocated, the operating system has no physical memory page to bring this page from.