static int mincore_unmapped_range(unsigned long addr, unsigned long end,
				   struct mm_walk *walk)
{
	unsigned char *vec = walk->private;
	unsigned long nr = (end - addr) >> PAGE_SHIFT;

	memset(vec, 0, nr);
	walk->private += nr;
	return 0;
}
static int mincore_unmapped_range(unsigned long addr, unsigned long end,
				   struct mm_walk *walk)
{
	unsigned char *vec = walk->private;
	unsigned long nr = (end - addr) >> PAGE_SHIFT;

	memset(vec, 0, nr);
	walk->private += nr;
	return 0;
}