AFAIK there is a difference between Linux and NT: Linux allows overcommitting, while NT requires that every page has a "backing store", for example a physical R

AFAIK there is a difference between Linux and NT: Linux allows overcommitting, while NT requires that every page has a "backing store", for example a physical RAM page, a swap page or a memory mapped file. Thus when you touch the page, Linux may figure out that there is no memory that page can be mapped to it, but now it is too late because the application "believes" that the memory has been allocated. So the kernel kills the application (or, to be correct, an application) too free memory with an OOM exception. This is one of the reasons why it is good to have loads of swap even if the physical RAM is big enough for all the running processes.