mmap a large range of memory which is larger than the total size of physical memory and swap

Posted on Mar 24, 2018 by Q A In QA

How to make mmap() a large range of memory which is larger than the total size of physical memory and swap successfully?

Short answer:

Adding the MAP_NORESERVE flag to mmap() to make it not reserve any swap space for the mapping.

For example:

rr_addr = mmap((void*)i, len, PROT_READ|PROT_WRITE, MAP_ANON|MAP_PRIVATE|MAP_NORESERVE, -1, 0);