zsmalloc: use copy_page for full page copy

Some architectures have implemented optimized copy_page for full page
copying, such as arm.

On my arm platform, use the copy_page helper for single page copying is
about 10 percent faster than memcpy.

Link: https://lkml.kernel.org/r/[email protected]
Signed-off-by: Mark-PK Tsai <[email protected]>
Reviewed-by: Sergey Senozhatsky <[email protected]>
Cc: AngeloGioacchino Del Regno <[email protected]>
Cc: Matthias Brugger <[email protected]>
Cc: Minchan Kim <[email protected]>
Cc: YJ Chiang <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>

Author: PeikanTsai

mm/zsmalloc.c

@@ -1839,7 +1839,7 @@ static int zs_page_migrate(struct page *newpage, struct page *page,
 	 * Here, any user cannot access all objects in the zspage so let's move.
 	 */
 	d_addr = kmap_atomic(newpage);
-	memcpy(d_addr, s_addr, PAGE_SIZE);
+	copy_page(d_addr, s_addr);
 	kunmap_atomic(d_addr);
 
 	for (addr = s_addr + offset; addr < s_addr + PAGE_SIZE;