mm/zsmalloc: use BUG_ON instead of if condition followed by BUG.

It can be optimized at compile time.

Link: https://lkml.kernel.org/r/1616727798-9110-1-git-send-email-zhouchuangao@vivo.com
Signed-off-by: zhouchuangao <zhouchuangao@vivo.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/zsmalloc.c

@@ -1987,8 +1987,7 @@ static int zs_page_migrate(struct address_space *mapping, struct page *newpage,
 		head = obj_to_head(page, addr);
 		if (head & OBJ_ALLOCATED_TAG) {
 			handle = head & ~OBJ_ALLOCATED_TAG;
-			if (!testpin_tag(handle))
-				BUG();
+			BUG_ON(!testpin_tag(handle));
 
 			old_obj = handle_to_obj(handle);
 			obj_to_location(old_obj, &dummy, &obj_idx);
@@ -2035,8 +2034,7 @@ unpin_objects:
 		head = obj_to_head(page, addr);
 		if (head & OBJ_ALLOCATED_TAG) {
 			handle = head & ~OBJ_ALLOCATED_TAG;
-			if (!testpin_tag(handle))
-				BUG();
+			BUG_ON(!testpin_tag(handle));
 			unpin_tag(handle);
 		}
 	}