mmap fails when length is larger than 4GB

Question

(The correct code is in \'Update 5\')

I tried to map a range of memory from 0x100000000 to 0x200000000 in this example C code:

#include 

        

Answer 1

If you do not actually have significantly more than 8G of swap configured, then that large mapping is likely to fail.

You can add the MAP_NORESERVE flag to mmap() to tell it not to reserve any swap space for the mapping up front.