kernel/bpf/verifier.c

281 	int map_uid;
1844 				reg->map_uid = reg->id;
7588 	meta->map_uid = reg->map_uid;
8675 			/* Use map_uid (which is unique id of inner map) to reject:
8688 			    meta->map_uid != reg->map_uid) {
8690 					"timer pointer in R1 map_uid=%d doesn't match map pointer in R2 map_uid=%d\n",
8691 					meta->map_uid, reg->map_uid);
8696 		meta->map_uid = reg->map_uid;
10515 		regs[BPF_REG_0].map_uid = meta.map_uid;