[PATCH] slab: fix display of object length in corruption detector

From: Manfred Spraul <manfred@colorfullife.com>

print_objinfo() dumps the first few characters of an interesting object for
debugging.  It used the wrong object len (including debug padding, instead
of just the data area), which could cause an oops if DEBUG_PAGEALLOC is
enabled.

mm/slab.c

@@ -914,7 +914,7 @@ static void print_objinfo(kmem_cache_t *cachep, void *objp, int lines)
 		printk("\n");
 	}
 	realobj = (char*)objp+obj_dbghead(cachep);
-	size = cachep->objsize;
+	size = obj_reallen(cachep);
 	for (i=0; i<size && lines;i+=16, lines--) {
 		int limit;
 		limit = 16;