bpf: Make __GFP_NOWARN consistent in bpf map creation

Some of the bpf maps are created with __GFP_NOWARN, i.e. arraymap,
bloom_filter, bpf_local_storage, bpf_struct_ops, lpm_trie,
queue_stack_maps, reuseport_array, stackmap and xskmap, while others are
created without __GFP_NOWARN, i.e. cpumap, devmap, hashtab,
local_storage, offload, ringbuf and sock_map. But there are not key
differences between the creation of these maps. So let make this
allocation flag consistent in all bpf maps creation. Then we can use a
generic helper to alloc all bpf maps.

Signed-off-by: Yafang Shao <laoar.shao@gmail.com>
Link: https://lore.kernel.org/r/20220810151840.16394-4-laoar.shao@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

kernel/bpf/ringbuf.c

@@ -164,7 +164,7 @@ static struct bpf_map *ringbuf_map_alloc(union bpf_attr *attr)
 		return ERR_PTR(-E2BIG);
 #endif
 
-	rb_map = kzalloc(sizeof(*rb_map), GFP_USER | __GFP_ACCOUNT);
+	rb_map = kzalloc(sizeof(*rb_map), GFP_USER | __GFP_NOWARN | __GFP_ACCOUNT);
 	if (!rb_map)
 		return ERR_PTR(-ENOMEM);