request_memory(): use MAP_PRIVATE in mmap()

src/request_memory_mmap_linux.c

@@ -39,7 +39,7 @@ void *request_memory(size_t size) {
     }
     fd = dev_zero_fd;
 
-    zone = mmap(0, size, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
+    zone = mmap(0, size, PROT_READ | PROT_WRITE, MAP_PRIVATE, fd, 0);
 
     if(zone == MAP_FAILED) {
         return NULL;