bpf: Refine memcg-based memory accounting for devmap maps

Include map metadata and the node size (struct bpf_dtab_netdev)
into the accounting.
Signed-off-by: Roman Gushchin <guro@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20201201215900.3569844-12-guro@fb.com

kernel/bpf/devmap.c

@@ -175,7 +175,7 @@ static struct bpf_map *dev_map_alloc(union bpf_attr *attr)
 	if (!capable(CAP_NET_ADMIN))
 		return ERR_PTR(-EPERM);
 
-	dtab = kzalloc(sizeof(*dtab), GFP_USER);
+	dtab = kzalloc(sizeof(*dtab), GFP_USER | __GFP_ACCOUNT);
 	if (!dtab)
 		return ERR_PTR(-ENOMEM);
 
@@ -602,7 +602,8 @@ static struct bpf_dtab_netdev *__dev_map_alloc_node(struct net *net,
 	struct bpf_prog *prog = NULL;
 	struct bpf_dtab_netdev *dev;
 
-	dev = kmalloc_node(sizeof(*dev), GFP_ATOMIC | __GFP_NOWARN,
+	dev = bpf_map_kmalloc_node(&dtab->map, sizeof(*dev),
+				   GFP_ATOMIC | __GFP_NOWARN,
 				   dtab->map.numa_node);
 	if (!dev)
 		return ERR_PTR(-ENOMEM);