[NET]: Set truesize in pskb_copy

Since pskb_copy tacks on the non-linear bits from the original
skb, it needs to count them in the truesize field of the new skb.
Signed-off-by: NHerbert Xu <herbert@gondor.apana.org.au>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/core/skbuff.c

@@ -639,6 +639,7 @@ struct sk_buff *pskb_copy(struct sk_buff *skb, gfp_t gfp_mask)
 	n->csum	     = skb->csum;
 	n->ip_summed = skb->ip_summed;
 
+	n->truesize += skb->data_len;
 	n->data_len  = skb->data_len;
 	n->len	     = skb->len;