SLUB: Avoid touching page struct when freeing to per cpu slab

Set c->node to -1 if we allocate from a debug slab instead for SlabDebug
which requires access the page struct cacheline.

Signed-off-by: Christoph Lameter <clameter@sgi.com>
Tested-by: Alexey Dobriyan <adobriyan@sw.ru>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/slub.c

@@ -1537,6 +1537,7 @@ static void *__slab_alloc(struct kmem_cache *s,
 
 	c->page->inuse++;
 	c->page->freelist = object[c->offset];
+	c->node = -1;
 	slab_unlock(c->page);
 	return object;
 }
@@ -1560,8 +1561,7 @@ static void __always_inline *slab_alloc(struct kmem_cache *s,
 
 	local_irq_save(flags);
 	c = get_cpu_slab(s, smp_processor_id());
-	if (unlikely(!c->page || !c->freelist ||
-					!node_match(c, node)))
+	if (unlikely(!c->freelist || !node_match(c, node)))
 
 		object = __slab_alloc(s, gfpflags, node, addr, c);
 
@@ -1670,7 +1670,7 @@ static void __always_inline slab_free(struct kmem_cache *s,
 	local_irq_save(flags);
 	debug_check_no_locks_freed(object, s->objsize);
 	c = get_cpu_slab(s, smp_processor_id());
-	if (likely(page == c->page && !SlabDebug(page))) {
+	if (likely(page == c->page && c->node >= 0)) {
 		object[c->offset] = c->freelist;
 		c->freelist = object;
 	} else
@@ -3250,12 +3250,16 @@ static unsigned long slab_objects(struct kmem_cache *s,
 
 	for_each_possible_cpu(cpu) {
 		struct page *page;
+		int node;
 		struct kmem_cache_cpu *c = get_cpu_slab(s, cpu);
 
 		if (!c)
 			continue;
 
 		page = c->page;
+		node = c->node;
+		if (node < 0)
+			continue;
 		if (page) {
 			if (flags & SO_CPU) {
 				int x = 0;
@@ -3265,9 +3269,9 @@ static unsigned long slab_objects(struct kmem_cache *s,
 				else
 					x = 1;
 				total += x;
-				nodes[c->node] += x;
+				nodes[node] += x;
 			}
-			per_cpu[c->node]++;
+			per_cpu[node]++;
 		}
 	}