+
+/**
+ * safe_copy_page - check if the page we are going to copy is marked as
+ * present in the kernel page tables (this always is the case if
+ * CONFIG_DEBUG_PAGEALLOC is not set and in that case
+ * kernel_page_present() always returns 'true').
+ */
+static void safe_copy_page(void *dst, struct page *s_page)
+{
+ if (kernel_page_present(s_page)) {
+ do_copy_page(dst, page_address(s_page));
+ } else {
+ kernel_map_pages(s_page, 1, 1);
+ do_copy_page(dst, page_address(s_page));
+ kernel_map_pages(s_page, 1, 0);
+ }
+}
+
+