linux-kernel - [PATCH 1,2/4 v4] slub: use __cmpxchg_double

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Date:	Fri, 18 May 2012 22:01:17 +0900
From:	Joonsoo Kim <js1304@...il.com>
To:	Pekka Enberg <penberg@...nel.org>
Cc:	Christoph Lameter <cl@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	Joonsoo Kim <js1304@...il.com>
Subject: [PATCH 1,2/4 v4] slub: use __cmpxchg_double_slab() at interrupt disabled place

get_freelist(), unfreeze_partials() are only called with interrupt disabled,
so __cmpxchg_double_slab() is suitable.

Acked-by: Christoph Lameter <cl@...ux.com>
Signed-off-by: Joonsoo Kim <js1304@...il.com>
---
According to comment from Pekka, add some comment.

diff --git a/mm/slub.c b/mm/slub.c
index 0c3105c..d7f8291 100644
--- a/mm/slub.c
+++ b/mm/slub.c
@@ -1879,7 +1879,11 @@ redo:
 	}
 }
 
-/* Unfreeze all the cpu partial slabs */
+/*
+ * Unfreeze all the cpu partial slabs.
+ *
+ * This function must be called with interrupt disabled.
+ */
 static void unfreeze_partials(struct kmem_cache *s)
 {
 	struct kmem_cache_node *n = NULL;
@@ -1935,7 +1939,7 @@ static void unfreeze_partials(struct kmem_cache *s)
 				l = m;
 			}
 
-		} while (!cmpxchg_double_slab(s, page,
+		} while (!__cmpxchg_double_slab(s, page,
 				old.freelist, old.counters,
 				new.freelist, new.counters,
 				"unfreezing slab"));
@@ -2163,6 +2167,8 @@ static inline void *new_slab_objects(struct kmem_cache *s, gfp_t flags,
  * The page is still frozen if the return value is not NULL.
  *
  * If this function returns NULL then the page has been unfrozen.
+ *
+ * This function must be called with interrupt disabled.
  */
 static inline void *get_freelist(struct kmem_cache *s, struct page *page)
 {
@@ -2179,7 +2185,7 @@ static inline void *get_freelist(struct kmem_cache *s, struct page *page)
 		new.inuse = page->objects;
 		new.frozen = freelist != NULL;
 
-	} while (!cmpxchg_double_slab(s, page,
+	} while (!__cmpxchg_double_slab(s, page,
 		freelist, counters,
 		NULL, new.counters,
 		"get_freelist"));
-- 
1.7.9.5

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