Ehh, that doesn&#x27;t apply to what he&#x27;s talking about though. That only works when the pages are actually freed. Since actually asking the kernel for more memory is expensive, most malloc&#x2F;calloc implementations will hold-on to some pages since it assumes you&#x27;re going to allocate more. Since it reuses this memory without ever giving it back to the kernel, the kernel won&#x27;t zero it for us.