slub: avoid duplicate creation on the first object
When a kmem_cache is created with ctor, each object in the kmem_cache
will be initialized before ready to use. While in slub implementation,
the first object will be initialized twice.
This patch reduces the duplication of initialization of the first
object.
Fix commit 7656c72b ("SLUB: add macros for scanning objects in a slab").
Signed-off-by: Wei Yang <weiyang@linux.vnet.ibm.com>
Acked-by: Christoph Lameter <cl@linux.com>
Cc: Pekka Enberg <penberg@kernel.org>
Cc: David Rientjes <rientjes@google.com>
Cc: Joonsoo Kim <iamjoonsoo.kim@lge.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/slub.c b/mm/slub.c
index 92d8139..1f1f838 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -283,6 +283,10 @@
for (__p = (__addr); __p < (__addr) + (__objects) * (__s)->size;\
__p += (__s)->size)
+#define for_each_object_idx(__p, __idx, __s, __addr, __objects) \
+ for (__p = (__addr), __idx = 1; __idx <= __objects;\
+ __p += (__s)->size, __idx++)
+
/* Determine object index from a given position */
static inline int slab_index(void *p, struct kmem_cache *s, void *addr)
{
@@ -1379,9 +1383,9 @@
{
struct page *page;
void *start;
- void *last;
void *p;
int order;
+ int idx;
BUG_ON(flags & GFP_SLAB_BUG_MASK);
@@ -1402,14 +1406,13 @@
if (unlikely(s->flags & SLAB_POISON))
memset(start, POISON_INUSE, PAGE_SIZE << order);
- last = start;
- for_each_object(p, s, start, page->objects) {
- setup_object(s, page, last);
- set_freepointer(s, last, p);
- last = p;
+ for_each_object_idx(p, idx, s, start, page->objects) {
+ setup_object(s, page, p);
+ if (likely(idx < page->objects))
+ set_freepointer(s, p, p + s->size);
+ else
+ set_freepointer(s, p, NULL);
}
- setup_object(s, page, last);
- set_freepointer(s, last, NULL);
page->freelist = start;
page->inuse = page->objects;