slub: current is always valid

Acked-by: NChristoph Lameter <clameter@sgi.com>
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NPekka Enberg <penberg@cs.helsinki.fi>

mm/slub.c

@@ -411,7 +411,7 @@ static void set_track(struct kmem_cache *s, void *object,
 	if (addr) {
 		p->addr = addr;
 		p->cpu = smp_processor_id();
-		p->pid = current ? current->pid : -1;
+		p->pid = current->pid;
 		p->when = jiffies;
 	} else
 		memset(p, 0, sizeof(struct track));