mm/memory.c: make apply_to_page_range() more robust

Arm and arm64 used to trigger this BUG_ON() - this has now been fixed.

But a WARN_ON() here is sufficient to catch future buggy callers.
Signed-off-by: NMika Penttilä <mika.penttila@nextfour.com>
Reviewed-by: NPekka Enberg <penberg@kernel.org>
Acked-by: NDavid Rientjes <rientjes@google.com>
Signed-off-by: NAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: NLinus Torvalds <torvalds@linux-foundation.org>

mm/memory.c

@@ -1876,7 +1876,9 @@ int apply_to_page_range(struct mm_struct *mm, unsigned long addr,
 	unsigned long end = addr + size;
 	int err;
 
-	BUG_ON(addr >= end);
+	if (WARN_ON(addr >= end))
+		return -EINVAL;
+
 	pgd = pgd_offset(mm, addr);
 	do {
 		next = pgd_addr_end(addr, end);