The Windows example is a non-sequitur as in both cases, you end up with the 36K sized process both in Windows and Linux if you want to spawn a sub-process that

The Windows example is a non-sequitur as in both cases, you end up with the 36K sized process both in Windows and Linux if you want to spawn a sub-process that exec's. The fork() => exec() path is not the issue (if there is an issue at all here), and if you use threading the memory is not forked like this to start with (on either of the OSes). I guess the case you want to highlight is more if you for example mmap() 10 GB of RAM on that 16 GB machine that only has 5 GB unused swap space left and where all of the physical RAM is filled with dirty pages already. Should the mmap() succeed, and then the process is killed if it eventually tries to use more pages than will fit in RAM or the backing swap? This is the overcommit option which is selectable on Linux. I think the defaults seem pretty good and accept that a process can get killed long after the "explicit" memory mapping call is done.