3 files changed, 25 insertions, 13 deletions

diff --git a/include/linux/skbuff.h b/include/linux/skbuff.h
index 06793b598f44..66e374d62f64 100644
--- a/include/linux/skbuff.h
+++ b/include/linux/skbuff.h
@@ -773,6 +773,7 @@ bool skb_try_coalesce(struct sk_buff *to, struct sk_buff *from,
 
 struct sk_buff *__alloc_skb(unsigned int size, gfp_t priority, int flags,
                             int node);
+struct sk_buff *__build_skb(void *data, unsigned int frag_size);
 struct sk_buff *build_skb(void *data, unsigned int frag_size);
 static inline struct sk_buff *alloc_skb(unsigned int size,
                                         gfp_t priority)
diff --git a/net/core/skbuff.c b/net/core/skbuff.c
index 456ead534e10..3cfff2a3d651 100644
--- a/net/core/skbuff.c
+++ b/net/core/skbuff.c
@@ -280,13 +280,14 @@ nodata:
 EXPORT_SYMBOL(__alloc_skb);
 
 /**
- * build_skb - build a network buffer
+ * __build_skb - build a network buffer
  * @data: data buffer provided by caller
- * @frag_size: size of fragment, or 0 if head was kmalloced
+ * @frag_size: size of data, or 0 if head was kmalloced
  *
  * Allocate a new &sk_buff. Caller provides space holding head and
  * skb_shared_info. @data must have been allocated by kmalloc() only if
- * @frag_size is 0, otherwise data should come from the page allocator.
+ * @frag_size is 0, otherwise data should come from the page allocator
+ *  or vmalloc()
  * The return is the new skb buffer.
  * On a failure the return is %NULL, and @data is not freed.
  * Notes :
@@ -297,7 +298,7 @@ EXPORT_SYMBOL(__alloc_skb);
  *  before giving packet to stack.
  *  RX rings only contains data buffers, not full skbs.
  */
-struct sk_buff *build_skb(void *data, unsigned int frag_size)
+struct sk_buff *__build_skb(void *data, unsigned int frag_size)
 {
         struct skb_shared_info *shinfo;
         struct sk_buff *skb;
@@ -311,11 +312,6 @@ struct sk_buff *build_skb(void *data, unsigned int frag_size)
 
         memset(skb, 0, offsetof(struct sk_buff, tail));
         skb->truesize = SKB_TRUESIZE(size);
-        if (frag_size) {
-                skb->head_frag = 1;
-                if (virt_to_head_page(data)->pfmemalloc)
-                        skb->pfmemalloc = 1;
-        }
         atomic_set(&skb->users, 1);
         skb->head = data;
         skb->data = data;
@@ -332,6 +328,23 @@ struct sk_buff *build_skb(void *data, unsigned int frag_size)
 
         return skb;
 }
+
+/* build_skb() is wrapper over __build_skb(), that specifically
+ * takes care of skb->head and skb->pfmemalloc
+ * This means that if @frag_size is not zero, then @data must be backed
+ * by a page fragment, not kmalloc() or vmalloc()
+ */
+struct sk_buff *build_skb(void *data, unsigned int frag_size)
+{
+        struct sk_buff *skb = __build_skb(data, frag_size);
+
+        if (skb && frag_size) {
+                skb->head_frag = 1;
+                if (virt_to_head_page(data)->pfmemalloc)
+                        skb->pfmemalloc = 1;
+        }
+        return skb;
+}
 EXPORT_SYMBOL(build_skb);
 
 struct netdev_alloc_cache {
diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 19909d0786a2..ec4adbdcb9b4 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -1629,13 +1629,11 @@ static struct sk_buff *netlink_alloc_large_skb(unsigned int size,
         if (data == NULL)
                 return NULL;
 
-        skb = build_skb(data, size);
+        skb = __build_skb(data, size);
         if (skb == NULL)
                 vfree(data);
-        else {
-                skb->head_frag = 0;
+        else
                 skb->destructor = netlink_skb_destructor;
-        }
 
         return skb;
 }