kernels/linux-2.4.0/include/linux/highmem.h
/* when CONFIG_HIGHMEM is not set these will be plain clear/copy_page */
when CONFIG_HIGHMEM is not set these will be plain clear/copy_page
when CONFIG_HIGHMEM is not set these will be plain clear / copy_page
static inline void clear_user_highpage(struct page *page, unsigned long vaddr)
{
	clear_user_page(kmap(page), vaddr);
	kunmap(page);
}
static inline void clear_user_highpage ( struct page * page , unsigned long vaddr ) { clear_user_page ( kmap ( page ) , vaddr ) ; kunmap ( page ) ; }
when CONFIG_HIGHMEM is not set these will be plain clear/copy_page
when CONFIG_HIGHMEM is not set these will be plain clear / copy_page