[slubll1 11/19] slub: explicit list_lock taking

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



The allocator fastpath rework does change the usage of the list_lock.
Remove the list_lock processing from the functions that hide them from the
critical sections and move them into those critical sections.

This is turn simplifies the support functions (no __ variant needed anymore)
and simplifies the lock handling on bootstrap.

Signed-off-by: Christoph Lameter <cl@xxxxxxxxx>

---
 mm/slub.c |   74 ++++++++++++++++++++++++++++++--------------------------------
 1 file changed, 36 insertions(+), 38 deletions(-)

Index: linux-2.6/mm/slub.c
===================================================================
--- linux-2.6.orig/mm/slub.c	2011-03-30 14:42:52.000000000 -0500
+++ linux-2.6/mm/slub.c	2011-03-30 14:42:55.000000000 -0500
@@ -904,25 +904,21 @@ static inline void slab_free_hook(struct
 /*
  * Tracking of fully allocated slabs for debugging purposes.
  */
-static void add_full(struct kmem_cache_node *n, struct page *page)
+static void add_full(struct kmem_cache *s,
+	struct kmem_cache_node *n, struct page *page)
 {
-	spin_lock(&n->list_lock);
+	if (!(s->flags & SLAB_STORE_USER))
+		return;
+
 	list_add(&page->lru, &n->full);
-	spin_unlock(&n->list_lock);
 }
 
 static void remove_full(struct kmem_cache *s, struct page *page)
 {
-	struct kmem_cache_node *n;
-
 	if (!(s->flags & SLAB_STORE_USER))
 		return;
 
-	n = get_node(s, page_to_nid(page));
-
-	spin_lock(&n->list_lock);
 	list_del(&page->lru);
-	spin_unlock(&n->list_lock);
 }
 
 /* Tracking of the number of slabs for debugging purposes */
@@ -1047,8 +1043,13 @@ static noinline int free_debug_processin
 	}
 
 	/* Special debug activities for freeing objects */
-	if (!page->frozen && !page->freelist)
+	if (!page->frozen && !page->freelist) {
+		struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+
+		spin_lock(&n->list_lock);
 		remove_full(s, page);
+		spin_unlock(&n->list_lock);
+	}
 	if (s->flags & SLAB_STORE_USER)
 		set_track(s, object, TRACK_FREE, addr);
 	trace(s, page, object, 0);
@@ -1399,36 +1400,26 @@ static __always_inline int slab_trylock(
 /*
  * Management of partially allocated slabs
  */
-static void add_partial(struct kmem_cache_node *n,
+static inline void add_partial(struct kmem_cache_node *n,
 				struct page *page, int tail)
 {
-	spin_lock(&n->list_lock);
 	n->nr_partial++;
 	if (tail)
 		list_add_tail(&page->lru, &n->partial);
 	else
 		list_add(&page->lru, &n->partial);
-	spin_unlock(&n->list_lock);
 }
 
-static inline void __remove_partial(struct kmem_cache_node *n,
+static inline void remove_partial(struct kmem_cache_node *n,
 					struct page *page)
 {
 	list_del(&page->lru);
 	n->nr_partial--;
 }
 
-static void remove_partial(struct kmem_cache *s, struct page *page)
-{
-	struct kmem_cache_node *n = get_node(s, page_to_nid(page));
-
-	spin_lock(&n->list_lock);
-	__remove_partial(n, page);
-	spin_unlock(&n->list_lock);
-}
-
 /*
- * Lock slab and remove from the partial list.
+ * Lock slab, remove from the partial list and put the object into the
+ * per cpu freelist.
  *
  * Must hold list_lock.
  */
@@ -1436,7 +1427,7 @@ static inline int lock_and_freeze_slab(s
 							struct page *page)
 {
 	if (slab_trylock(page)) {
-		__remove_partial(n, page);
+		remove_partial(n, page);
 		return 1;
 	}
 	return 0;
@@ -1553,12 +1544,17 @@ static void unfreeze_slab(struct kmem_ca
 	if (page->inuse) {
 
 		if (page->freelist) {
+			spin_lock(&n->list_lock);
 			add_partial(n, page, tail);
+			spin_unlock(&n->list_lock);
 			stat(s, tail ? DEACTIVATE_TO_TAIL : DEACTIVATE_TO_HEAD);
 		} else {
 			stat(s, DEACTIVATE_FULL);
-			if (kmem_cache_debug(s) && (s->flags & SLAB_STORE_USER))
-				add_full(n, page);
+			if (kmem_cache_debug(s) && (s->flags & SLAB_STORE_USER)) {
+				spin_lock(&n->list_lock);
+				add_full(s, n, page);
+				spin_unlock(&n->list_lock);
+			}
 		}
 		slab_unlock(page);
 	} else {
@@ -1574,7 +1570,9 @@ static void unfreeze_slab(struct kmem_ca
 			 * kmem_cache_shrink can reclaim any empty slabs from
 			 * the partial list.
 			 */
+			spin_lock(&n->list_lock);
 			add_partial(n, page, 1);
+			spin_unlock(&n->list_lock);
 			slab_unlock(page);
 		} else {
 			slab_unlock(page);
@@ -2114,7 +2112,11 @@ static void __slab_free(struct kmem_cach
 	 * then add it.
 	 */
 	if (unlikely(!prior)) {
+		struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+
+		spin_lock(&n->list_lock);
 		add_partial(get_node(s, page_to_nid(page)), page, 1);
+		spin_unlock(&n->list_lock);
 		stat(s, FREE_ADD_PARTIAL);
 	}
 
@@ -2130,7 +2132,11 @@ slab_empty:
 		/*
 		 * Slab still on the partial list.
 		 */
-		remove_partial(s, page);
+		struct kmem_cache_node *n = get_node(s, page_to_nid(page));
+
+		spin_lock(&n->list_lock);
+		remove_partial(n, page);
+		spin_unlock(&n->list_lock);
 		stat(s, FREE_REMOVE_PARTIAL);
 	}
 	slab_unlock(page);
@@ -2432,7 +2438,6 @@ static void early_kmem_cache_node_alloc(
 {
 	struct page *page;
 	struct kmem_cache_node *n;
-	unsigned long flags;
 
 	BUG_ON(kmem_cache_node->size < sizeof(struct kmem_cache_node));
 
@@ -2459,14 +2464,7 @@ static void early_kmem_cache_node_alloc(
 	init_kmem_cache_node(n, kmem_cache_node);
 	inc_slabs_node(kmem_cache_node, node, page->objects);
 
-	/*
-	 * lockdep requires consistent irq usage for each lock
-	 * so even though there cannot be a race this early in
-	 * the boot sequence, we still disable irqs.
-	 */
-	local_irq_save(flags);
 	add_partial(n, page, 0);
-	local_irq_restore(flags);
 }
 
 static void free_kmem_cache_nodes(struct kmem_cache *s)
@@ -2744,7 +2742,7 @@ static void free_partial(struct kmem_cac
 	spin_lock_irqsave(&n->list_lock, flags);
 	list_for_each_entry_safe(page, h, &n->partial, lru) {
 		if (!page->inuse) {
-			__remove_partial(n, page);
+			remove_partial(n, page);
 			discard_slab(s, page);
 		} else {
 			list_slab_objects(s, page,
@@ -3082,7 +3080,7 @@ int kmem_cache_shrink(struct kmem_cache
 				 * may have freed the last object and be
 				 * waiting to release the slab.
 				 */
-				__remove_partial(n, page);
+				remove_partial(n, page);
 				slab_unlock(page);
 				discard_slab(s, page);
 			} else {

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@xxxxxxxxxx  For more info on Linux MM,
see: http://www.linux-mm.org/ .
Fight unfair telecom internet charges in Canada: sign http://stopthemeter.ca/
Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>


[Index of Archives]     [Linux ARM Kernel]     [Linux ARM]     [Linux Omap]     [Fedora ARM]     [IETF Annouce]     [Bugtraq]     [Linux]     [Linux OMAP]     [Linux MIPS]     [ECOS]     [Asterisk Internet PBX]     [Linux API]