Memory issues - example

  drivers/usb/audio.c

    static int dmabuf_mmap(...)
    {
      size >>= PAGE_SHIFT;
      for (nr = 0; nr < size; nr++)
        if (!db->sgbuf[nr])
          return -EINVAL;
      db->mapped = 1;
      for (nr = 0; nr < size; nr++) {
        if (remap_page_range(start, 
                               virt_to_phys(db->sgbuf[nr]),
                               PAGE_SIZE, prot))
          return -EAGAIN;
        start += PAGE_SIZE;
      }
      return 0;
    }