Malloc allocates memory more than RAM

Question

I just executed a program that mallocs 13 MB in a 12 MB machine (QEMU Emulated!) . Not just that, i even browsed through the memory and filled junk in it...

Answer 1

Sounds like your operating system is swapping pages:

Paging is an important part of virtual memory implementation in most contemporary general-purpose operating systems, allowing them to use disk storage for data that does not fit into physical random-access memory (RAM).

In other words, the operating system is using some of your hard disk space to satisfy your 13 MB allocation request (at great expense of speed, since the hard disk is much, much slower than RAM).