netfilter: conntrack: table full detailed log

Add the netns field in the "nf_conntrack: table full, dropping packet"
log to help locate the specific netns when the table is full.

Signed-off-by: lvxiafei <[e-mail]>
Signed-off-by: Pablo Neira Ayuso <[e-mail]>

net/netfilter/nf_conntrack_core.c

···
 			if (!conntrack_gc_work.early_drop)
 				conntrack_gc_work.early_drop = true;
 			atomic_dec(&cnet->count);
-			net_warn_ratelimited("nf_conntrack: table full, dropping packet\n");
+			if (net == &init_net)
+				net_warn_ratelimited("nf_conntrack: table full, dropping packet\n");
+			else
+				net_warn_ratelimited("nf_conntrack: table full in netns %u, dropping packet\n",
+						     net->ns.inum);
 			return ERR_PTR(-ENOMEM);
 		}
 	}