slub: Acquire_slab() avoid loop

Avoid the loop in acquire slab and simply fail if there is a conflict.

This will cause the next page on the list to be considered.

Acked-by: David Rientjes <[email protected]>
Signed-off-by: Christoph Lameter <[email protected]>
Signed-off-by: Pekka Enberg <[email protected]>

diff --git a/mm/slub.c b/mm/slub.c
index a3395c28f5610ec542c0e0a2c8be757bbe5598f7..9892775349bfc5a53d20388ed2cb454f3d84dcd9 100644 (file)
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1490,12 +1490,12 @@ static inline void remove_partial(struct kmem_cache_node *n,
 }
 
 /*
 }
 
 /*

- * Lock slab, remove from the partial list and put the object into the
- * per cpu freelist.
+ * Remove slab from the partial list, freeze it and
+ * return the pointer to the freelist.

  *
  * Returns a list of objects or NULL if it fails.
  *
  *
  * Returns a list of objects or NULL if it fails.
  *

- * Must hold list_lock.
+ * Must hold list_lock since we modify the partial list.

  */
 static inline void *acquire_slab(struct kmem_cache *s,
                struct kmem_cache_node *n, struct page *page,
  */
 static inline void *acquire_slab(struct kmem_cache *s,
                struct kmem_cache_node *n, struct page *page,


@@ -1510,22 +1510,24 @@ static inline void *acquire_slab(struct kmem_cache *s,
         * The old freelist is the list of objects for the
         * per cpu allocation list.
         */
         * The old freelist is the list of objects for the
         * per cpu allocation list.
         */

-       do {
-               freelist = page->freelist;
-               counters = page->counters;
-               new.counters = counters;
-               if (mode)
-                       new.inuse = page->objects;
+       freelist = page->freelist;
+       counters = page->counters;
+       new.counters = counters;
+       if (mode)
+               new.inuse = page->objects;

 
 

-               VM_BUG_ON(new.frozen);
-               new.frozen = 1;
+       VM_BUG_ON(new.frozen);
+       new.frozen = 1;

 
 

-       } while (!__cmpxchg_double_slab(s, page,
+       if (!__cmpxchg_double_slab(s, page,

                        freelist, counters,
                        NULL, new.counters,
                        freelist, counters,
                        NULL, new.counters,

-                       "lock and freeze"));
+                       "acquire_slab"))
+
+               return NULL;

 
        remove_partial(n, page);
 
        remove_partial(n, page);

+       WARN_ON(!freelist);

        return freelist;
 }
 
        return freelist;
 }