bpf: do not test for PCPU_MIN_UNIT_SIZE before percpu allocations

PCPU_MIN_UNIT_SIZE is an implementation detail of the percpu
allocator. Given we support __GFP_NOWARN now, lets just let
the allocation request fail naturally instead. The two call
sites from BPF mistakenly assumed __GFP_NOWARN would work, so
no changes needed to their actual __alloc_percpu_gfp() calls
which use the flag already.

Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

kernel/bpf/arraymap.c

@@ -98,7 +98,7 @@ static struct bpf_map *array_map_alloc(union bpf_attr *attr)
 	array_size += (u64) attr->max_entries * elem_size * num_possible_cpus();
 
 	if (array_size >= U32_MAX - PAGE_SIZE ||
-	    elem_size > PCPU_MIN_UNIT_SIZE || bpf_array_alloc_percpu(array)) {
+	    bpf_array_alloc_percpu(array)) {
 		bpf_map_area_free(array);
 		return ERR_PTR(-ENOMEM);
 	}

kernel/bpf/hashtab.c

@@ -317,10 +317,6 @@ static struct bpf_map *htab_map_alloc(union bpf_attr *attr)
 		 */
 		goto free_htab;
 
-	if (percpu && round_up(htab->map.value_size, 8) > PCPU_MIN_UNIT_SIZE)
-		/* make sure the size for pcpu_alloc() is reasonable */
-		goto free_htab;
-
 	htab->elem_size = sizeof(struct htab_elem) +
 			  round_up(htab->map.key_size, 8);
 	if (percpu)