bpf: Skip unit_size checking for global per-cpu allocator

For global per-cpu allocator, the size of free object in free list
doesn't match with unit_size and now there is no way to get the size of
per-cpu pointer saved in free object, so just skip the checking.

Signed-off-by: Hou Tao <houtao1@huawei.com>

kernel/bpf/memalloc.c

diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c
index aad558c..0ad1752 100644
--- a/kernel/bpf/memalloc.c
+++ b/kernel/bpf/memalloc.c
@@ -491,6 +491,13 @@ static int check_obj_size(struct bpf_mem_cache *c, unsigned int idx)
 	struct llist_node *first;
 	unsigned int obj_size;
 
+	/* For per-cpu allocator, the size of free objects in free list doesn't
+	 * match with unit_size and now there is no way to get the size of
+	 * per-cpu pointer saved in free object, so just skip the checking.
+	 */
+	if (c->percpu_size)
+		return 0;
+
 	first = c->free_llist.first;
 	if (!first)
 		return 0;