mmap_align.c

#include <sys/mman.h>
#include <stdlib.h>
#include <stdio.h>
#include <stddef.h>

int main()
{
  ptrdiff_t offset = 1L << 36;
  void* addr = NULL + offset;
  void* map_addr;
  for (int i = 0; i < 64; i++)
    {
      map_addr = mmap(addr, 1UL << 36,
        PROT_READ | PROT_WRITE,
        MAP_ANON | MAP_PRIVATE | MAP_FIXED,
        -1, 0);
      if (map_addr == MAP_FAILED)
        { 
          printf("map failed on %p\n", addr);
          addr += offset;
        }
      else
        {
          printf("successfully mmap on %p\n", map_addr);
          break;
        }
    }
  return 0;
}