 <p>Linux already has a kernel process that is zeroing memory using idle cycles so it will have memory ready to hand to processes that request it.</p> <p>Your loop may or may not zero different memory depending on the particular <code>malloc</code> implementation. If you really want to write a process like you describe, look into using <code>sbrk</code> directly to ensure you're cycling memory in and out of your process. I bet if you check you'll find every byte given to you by <code>sbrk</code> is already zero, though.</p>