netfilter: ctnetlink: fix GFP_KERNEL allocation under spinlock

The previous fix for the conntrack creation race (netfilter: ctnetlink:
fix conntrack creation race) missed a GFP_KERNEL allocation that is
now performed while holding a spinlock. Switch to GFP_ATOMIC.
Reported-and-tested-by: NZoltan Borbely <bozo@andrews.hu>
Signed-off-by: NPatrick McHardy <kaber@trash.net>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/netfilter/nf_conntrack_netlink.c

@@ -1138,7 +1138,7 @@ ctnetlink_create_conntrack(struct nlattr *cda[],
 		}
 	}
 
-	nf_ct_acct_ext_add(ct, GFP_KERNEL);
+	nf_ct_acct_ext_add(ct, GFP_ATOMIC);
 
 #if defined(CONFIG_NF_CONNTRACK_MARK)
 	if (cda[CTA_MARK])