mem: handle errors of page_xfer_dump_pages()

Signed-off-by: Andrey Vagin <avagin@openvz.org>
Signed-off-by: Pavel Emelyanov <xemul@parallels.com>

mem.c

@@ -412,6 +412,8 @@ static int __parasite_dump_pages_seized(struct parasite_ctl *ctl,
 			goto out_pp;
 
 		ret = page_xfer_dump_pages(&xfer, pp, 0);
+		if (ret < 0)
+			goto out_pp;
 
 		xfer.close(&xfer);
 		timing_stop(TIME_MEMWRITE);