bpf: add memlock precharge for socket local storage

Socket local storage maps lack the memlock precharge check,
which is performed before the memory allocation for
most other bpf map types.

Let's add it in order to unify all map types.
Signed-off-by: Roman Gushchin <guro@fb.com>
Acked-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>

net/core/bpf_sk_storage.c

@@ -626,7 +626,9 @@ static struct bpf_map *bpf_sk_storage_map_alloc(union bpf_attr *attr)
 	struct bpf_sk_storage_map *smap;
 	unsigned int i;
 	u32 nbuckets;
+	u32 pages;
 	u64 cost;
+	int ret;
 
 	smap = kzalloc(sizeof(*smap), GFP_USER | __GFP_NOWARN);
 	if (!smap)
@@ -635,13 +637,19 @@ static struct bpf_map *bpf_sk_storage_map_alloc(union bpf_attr *attr)
 
 	smap->bucket_log = ilog2(roundup_pow_of_two(num_possible_cpus()));
 	nbuckets = 1U << smap->bucket_log;
+	cost = sizeof(*smap->buckets) * nbuckets + sizeof(*smap);
+	pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
+
+	ret = bpf_map_precharge_memlock(pages);
+	if (ret < 0)
+		return ERR_PTR(ret);
+
 	smap->buckets = kvcalloc(sizeof(*smap->buckets), nbuckets,
 				 GFP_USER | __GFP_NOWARN);
 	if (!smap->buckets) {
 		kfree(smap);
 		return ERR_PTR(-ENOMEM);
 	}
-	cost = sizeof(*smap->buckets) * nbuckets + sizeof(*smap);
 
 	for (i = 0; i < nbuckets; i++) {
 		INIT_HLIST_HEAD(&smap->buckets[i].list);
@@ -651,7 +659,7 @@ static struct bpf_map *bpf_sk_storage_map_alloc(union bpf_attr *attr)
 	smap->elem_size = sizeof(struct bpf_sk_storage_elem) + attr->value_size;
 	smap->cache_idx = (unsigned int)atomic_inc_return(&cache_idx) %
 		BPF_SK_STORAGE_CACHE_SIZE;
-	smap->map.pages = round_up(cost, PAGE_SIZE) >> PAGE_SHIFT;
+	smap->map.pages = pages;
 
 	return &smap->map;
 }