Not really, no. The kernel has a certain overhead tracking pages and page tables, so adding extra memory and waiting for it to be swapped in isn't free. Plus

Not really, no. The kernel has a certain overhead tracking pages and page tables, so adding extra memory and waiting for it to be swapped in isn't free. Plus you still have to account for the memory being used somehow. If you use cgroups - as is done most commonly - that will track the full memory allocated. Not to mention this would only solve half of the problem, you also have to think about what happens with munmap.