5 files changed, 127 insertions, 97 deletions

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 97a9373e61e8..70a7fee1efb3 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -366,6 +366,11 @@ extern void free_pages(unsigned long addr, unsigned int order);
 extern void free_hot_cold_page(struct page *page, bool cold);
 extern void free_hot_cold_page_list(struct list_head *list, bool cold);
 
+struct page_frag_cache;
+extern void *__alloc_page_frag(struct page_frag_cache *nc,
+			       unsigned int fragsz, gfp_t gfp_mask);
+extern void __free_page_frag(void *addr);
+
 extern void __free_kmem_pages(struct page *page, unsigned int order);
 extern void free_kmem_pages(unsigned long addr, unsigned int order);
 
diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 8d37e26a1007..0038ac7466fd 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -226,6 +226,24 @@ struct page_frag {
 #endif
 };
 
+#define PAGE_FRAG_CACHE_MAX_SIZE	__ALIGN_MASK(32768, ~PAGE_MASK)
+#define PAGE_FRAG_CACHE_MAX_ORDER	get_order(PAGE_FRAG_CACHE_MAX_SIZE)
+
+struct page_frag_cache {
+	void * va;
+#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
+	__u16 offset;
+	__u16 size;
+#else
+	__u32 offset;
+#endif
+	/* we maintain a pagecount bias, so that we dont dirty cache line
+	 * containing page->_count every time we allocate a fragment.
+	 */
+	unsigned int		pagecnt_bias;
+	bool pfmemalloc;
+};
+
 typedef unsigned long __nocast vm_flags_t;
 
 /*
diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 8b9a2c35a9d7..0039fcc45b3b 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -2128,9 +2128,6 @@ static inline void __skb_queue_purge(struct sk_buff_head *list)
 		kfree_skb(skb);
 }
 
-#define NETDEV_FRAG_PAGE_MAX_SIZE	__ALIGN_MASK(32768, ~PAGE_MASK)
-#define NETDEV_FRAG_PAGE_MAX_ORDER	get_order(NETDEV_FRAG_PAGE_MAX_SIZE)
-
 void *netdev_alloc_frag(unsigned int fragsz);
 
 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int length,
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index ebffa0e4a9c0..2fd31aebef30 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -2967,6 +2967,104 @@ void free_pages(unsigned long addr, unsigned int order)
 EXPORT_SYMBOL(free_pages);
 
 /*
+ * Page Fragment:
+ *  An arbitrary-length arbitrary-offset area of memory which resides
+ *  within a 0 or higher order page.  Multiple fragments within that page
+ *  are individually refcounted, in the page's reference counter.
+ *
+ * The page_frag functions below provide a simple allocation framework for
+ * page fragments.  This is used by the network stack and network device
+ * drivers to provide a backing region of memory for use as either an
+ * sk_buff->head, or to be used in the "frags" portion of skb_shared_info.
+ */
+static struct page *__page_frag_refill(struct page_frag_cache *nc,
+				       gfp_t gfp_mask)
+{
+	struct page *page = NULL;
+	gfp_t gfp = gfp_mask;
+
+#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
+	gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY |
+		    __GFP_NOMEMALLOC;
+	page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
+				PAGE_FRAG_CACHE_MAX_ORDER);
+	nc->size = page ? PAGE_FRAG_CACHE_MAX_SIZE : PAGE_SIZE;
+#endif
+	if (unlikely(!page))
+		page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
+
+	nc->va = page ? page_address(page) : NULL;
+
+	return page;
+}
+
+void *__alloc_page_frag(struct page_frag_cache *nc,
+			unsigned int fragsz, gfp_t gfp_mask)
+{
+	unsigned int size = PAGE_SIZE;
+	struct page *page;
+	int offset;
+
+	if (unlikely(!nc->va)) {
+refill:
+		page = __page_frag_refill(nc, gfp_mask);
+		if (!page)
+			return NULL;
+
+#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
+		/* if size can vary use size else just use PAGE_SIZE */
+		size = nc->size;
+#endif
+		/* Even if we own the page, we do not use atomic_set().
+		 * This would break get_page_unless_zero() users.
+		 */
+		atomic_add(size - 1, &page->_count);
+
+		/* reset page count bias and offset to start of new frag */
+		nc->pfmemalloc = page->pfmemalloc;
+		nc->pagecnt_bias = size;
+		nc->offset = size;
+	}
+
+	offset = nc->offset - fragsz;
+	if (unlikely(offset < 0)) {
+		page = virt_to_page(nc->va);
+
+		if (!atomic_sub_and_test(nc->pagecnt_bias, &page->_count))
+			goto refill;
+
+#if (PAGE_SIZE < PAGE_FRAG_CACHE_MAX_SIZE)
+		/* if size can vary use size else just use PAGE_SIZE */
+		size = nc->size;
+#endif
+		/* OK, page count is 0, we can safely set it */
+		atomic_set(&page->_count, size);
+
+		/* reset page count bias and offset to start of new frag */
+		nc->pagecnt_bias = size;
+		offset = size - fragsz;
+	}
+
+	nc->pagecnt_bias--;
+	nc->offset = offset;
+
+	return nc->va + offset;
+}
+EXPORT_SYMBOL(__alloc_page_frag);
+
+/*
+ * Frees a page fragment allocated out of either a compound or order 0 page.
+ */
+void __free_page_frag(void *addr)
+{
+	struct page *page = virt_to_head_page(addr);
+
+	if (unlikely(put_page_testzero(page)))
+		__free_pages_ok(page, compound_order(page));
+}
+EXPORT_SYMBOL(__free_page_frag);
+
+/*
  * alloc_kmem_pages charges newly allocated pages to the kmem resource counter
  * of the current memory cgroup.
  *
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index a3062ec341c3..dcc0e07abf47 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -347,100 +347,12 @@ struct sk_buff *build_skb(void *data, unsigned int frag_size)
 }
 EXPORT_SYMBOL(build_skb);
 
-struct netdev_alloc_cache {
-	void * va;
-#if (PAGE_SIZE < NETDEV_FRAG_PAGE_MAX_SIZE)
-	__u16 offset;
-	__u16 size;
-#else
-	__u32 offset;
-#endif
-	/* we maintain a pagecount bias, so that we dont dirty cache line
-	 * containing page->_count every time we allocate a fragment.
-	 */
-	unsigned int		pagecnt_bias;
-	bool pfmemalloc;
-};
-static DEFINE_PER_CPU(struct netdev_alloc_cache, netdev_alloc_cache);
-static DEFINE_PER_CPU(struct netdev_alloc_cache, napi_alloc_cache);
-
-static struct page *__page_frag_refill(struct netdev_alloc_cache *nc,
-				       gfp_t gfp_mask)
-{
-	struct page *page = NULL;
-	gfp_t gfp = gfp_mask;
-
-#if (PAGE_SIZE < NETDEV_FRAG_PAGE_MAX_SIZE)
-	gfp_mask |= __GFP_COMP | __GFP_NOWARN | __GFP_NORETRY |
-		    __GFP_NOMEMALLOC;
-	page = alloc_pages_node(NUMA_NO_NODE, gfp_mask,
-				NETDEV_FRAG_PAGE_MAX_ORDER);
-	nc->size = page ? NETDEV_FRAG_PAGE_MAX_SIZE : PAGE_SIZE;
-#endif
-	if (unlikely(!page))
-		page = alloc_pages_node(NUMA_NO_NODE, gfp, 0);
-
-	nc->va = page ? page_address(page) : NULL;
-
-	return page;
-}
-
-static void *__alloc_page_frag(struct netdev_alloc_cache *nc,
-			       unsigned int fragsz, gfp_t gfp_mask)
-{
-	unsigned int size = PAGE_SIZE;
-	struct page *page;
-	int offset;
-
-	if (unlikely(!nc->va)) {
-refill:
-		page = __page_frag_refill(nc, gfp_mask);
-		if (!page)
-			return NULL;
-
-#if (PAGE_SIZE < NETDEV_FRAG_PAGE_MAX_SIZE)
-		/* if size can vary use size else just use PAGE_SIZE */
-		size = nc->size;
-#endif
-		/* Even if we own the page, we do not use atomic_set().
-		 * This would break get_page_unless_zero() users.
-		 */
-		atomic_add(size - 1, &page->_count);
-
-		/* reset page count bias and offset to start of new frag */
-		nc->pfmemalloc = page->pfmemalloc;
-		nc->pagecnt_bias = size;
-		nc->offset = size;
-	}
-
-	offset = nc->offset - fragsz;
-	if (unlikely(offset < 0)) {
-		page = virt_to_page(nc->va);
-
-		if (!atomic_sub_and_test(nc->pagecnt_bias, &page->_count))
-			goto refill;
-
-#if (PAGE_SIZE < NETDEV_FRAG_PAGE_MAX_SIZE)
-		/* if size can vary use size else just use PAGE_SIZE */
-		size = nc->size;
-#endif
-		/* OK, page count is 0, we can safely set it */
-		atomic_set(&page->_count, size);
-
-		/* reset page count bias and offset to start of new frag */
-		nc->pagecnt_bias = size;
-		offset = size - fragsz;
-	}
-
-	nc->pagecnt_bias--;
-	nc->offset = offset;
-
-	return nc->va + offset;
-}
+static DEFINE_PER_CPU(struct page_frag_cache, netdev_alloc_cache);
+static DEFINE_PER_CPU(struct page_frag_cache, napi_alloc_cache);
 
 static void *__netdev_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
 {
-	struct netdev_alloc_cache *nc;
+	struct page_frag_cache *nc;
 	unsigned long flags;
 	void *data;
 
@@ -466,7 +378,7 @@ EXPORT_SYMBOL(netdev_alloc_frag);
 
 static void *__napi_alloc_frag(unsigned int fragsz, gfp_t gfp_mask)
 {
-	struct netdev_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
+	struct page_frag_cache *nc = this_cpu_ptr(&napi_alloc_cache);
 
 	return __alloc_page_frag(nc, fragsz, gfp_mask);
 }
@@ -493,7 +405,7 @@ EXPORT_SYMBOL(napi_alloc_frag);
 struct sk_buff *__netdev_alloc_skb(struct net_device *dev, unsigned int len,
 				   gfp_t gfp_mask)
 {
-	struct netdev_alloc_cache *nc;
+	struct page_frag_cache *nc;
 	unsigned long flags;
 	struct sk_buff *skb;
 	bool pfmemalloc;
@@ -556,7 +468,7 @@ EXPORT_SYMBOL(__netdev_alloc_skb);
 struct sk_buff *__napi_alloc_skb(struct napi_struct *napi, unsigned int len,
 				 gfp_t gfp_mask)
 {
-	struct netdev_alloc_cache *nc = this_cpu_ptr(&napi_alloc_cache);
+	struct page_frag_cache *nc = this_cpu_ptr(&napi_alloc_cache);
 	struct sk_buff *skb;
 	void *data;