kernel_page_present
bool kernel_page_present(struct page *page);
bool kernel_page_present(struct page *page);
bool kernel_page_present(struct page *page);
bool kernel_page_present(struct page *page);
bool kernel_page_present(struct page *page);
&& (!kernel_page_present(page) || pfn_is_nosave(pfn)))
if (kernel_page_present(s_page)) {