get_freelist retrieves free objects from the page freelist (put there by remote
frees) or deactivates a slab page if no more objects are available.
Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>
---
mm/slub.c | 57 ++++++++++++++++++++++++++++++++-------------------------
1 file changed, 32 insertions(+), 25 deletions(-)
Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c 2011-09-02 08:20:25.911219458 -0500
+++ linux-2.6/mm/slub.c 2011-09-02 08:20:32.491219417 -0500
@@ -2024,6 +2024,37 @@ slab_out_of_memory(struct kmem_cache *s,
}
/*
+ * Check the page->freelist of a page and either transfer the freelist to the per cpu freelist
+ * or deactivate the page.
+ *
+ * The page is still frozen if the return value is not NULL.
+ *
+ * If this function returns NULL then the page has been unfrozen.
+ */
+static inline void *get_freelist(struct kmem_cache *s, struct page *page)
+{
+ struct page new;
+ unsigned long counters;
+ void *freelist;
+
+ do {
+ freelist = page->freelist;
+ counters = page->counters;
+ new.counters = counters;
+ VM_BUG_ON(!new.frozen);
+
+ new.inuse = page->objects;
+ new.frozen = freelist != NULL;
+
+ } while (!cmpxchg_double_slab(s, page,
+ freelist, counters,
+ NULL, new.counters,
+ "get_freelist"));
+
+ return freelist;
+}
+
+/*
* Slow path. The lockless freelist is empty or we need to perform
* debugging duties.
*
@@ -2047,8 +2078,6 @@ static void *__slab_alloc(struct kmem_ca
void **object;
struct page *page;
unsigned long flags;
- struct page new;
- unsigned long counters;
local_irq_save(flags);
#ifdef CONFIG_PREEMPT
@@ -2074,29 +2103,7 @@ static void *__slab_alloc(struct kmem_ca
stat(s, ALLOC_SLOWPATH);
- do {
- object = page->freelist;
- counters = page->counters;
- new.counters = counters;
- VM_BUG_ON(!new.frozen);
-
- /*
- * If there is no object left then we use this loop to
- * deactivate the slab which is simple since no objects
- * are left in the slab and therefore we do not need to
- * put the page back onto the partial list.
- *
- * If there are objects left then we retrieve them
- * and use them to refill the per cpu queue.
- */
-
- new.inuse = page->objects;
- new.frozen = object != NULL;
-
- } while (!__cmpxchg_double_slab(s, page,
- object, counters,
- NULL, new.counters,
- "__slab_alloc"));
+ object = get_freelist(s, page);
if (unlikely(!object)) {
c->page = NULL;
--
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