handle mismatch peer id region error

internal/locate/region_request.go

@@ -1882,6 +1882,8 @@ func regionErrorToLabel(e *errorpb.Error) string {
 		return "peer_is_witness"
 	} else if isDeadlineExceeded(e) {
 		return "deadline_exceeded"
+	} else if e.GetMismatchPeerId() != nil {
+		return "mismatch_peer_id"
 	}
 	return "unknown"
 }
@@ -2173,6 +2175,18 @@ func (s *RegionRequestSender) onRegionError(
 		s.replicaSelector.onDeadlineExceeded()
 	}
 
+	if mismatch := regionErr.GetMismatchPeerId(); mismatch != nil {
+		logutil.Logger(bo.GetCtx()).Warn(
+			"tikv reports `MismatchPeerId`, invalidate region cache",
+			zap.Uint64("req peer id", mismatch.GetRequestPeerId()),
+			zap.Uint64("store peer id", mismatch.GetStorePeerId()),
+		)
+		if s.replicaSelector != nil {
+			s.replicaSelector.invalidateRegion()
+		}
+		return false, nil
+	}
+
 	logutil.Logger(bo.GetCtx()).Debug(
 		"tikv reports region failed",
 		zap.Stringer("regionErr", regionErr),

internal/locate/region_request3_test.go

@@ -1376,3 +1376,52 @@ func (s *testRegionRequestToThreeStoresSuite) TestStaleReadFallback2Follower() {
 		}
 	}
 }
+
+func (s *testRegionRequestToThreeStoresSuite) TestReplicaReadFallbackToLeaderRegionError() {
+	regionLoc, err := s.cache.LocateRegionByID(s.bo, s.regionID)
+	s.Nil(err)
+	s.NotNil(regionLoc)
+
+	s.regionRequestSender.client = &fnClient{fn: func(ctx context.Context, addr string, req *tikvrpc.Request, timeout time.Duration) (response *tikvrpc.Response, err error) {
+		select {
+		case <-ctx.Done():
+			return nil, errors.New("timeout")
+		default:
+		}
+		// Return `mismatch peer id` when accesses the leader.
+		if addr == s.cluster.GetStore(s.storeIDs[0]).Address {
+			return &tikvrpc.Response{Resp: &kvrpcpb.GetResponse{RegionError: &errorpb.Error{
+				MismatchPeerId: &errorpb.MismatchPeerId{
+					RequestPeerId: 1,
+					StorePeerId:   2,
+				},
+			}}}, nil
+		}
+		return &tikvrpc.Response{Resp: &kvrpcpb.GetResponse{RegionError: &errorpb.Error{
+			DataIsNotReady: &errorpb.DataIsNotReady{},
+		}}}, nil
+	}}
+
+	region := s.cache.getRegionByIDFromCache(regionLoc.Region.GetID())
+	s.True(region.isValid())
+
+	req := tikvrpc.NewReplicaReadRequest(tikvrpc.CmdGet, &kvrpcpb.GetRequest{Key: []byte("key")}, kv.ReplicaReadLeader, nil)
+	req.ReadReplicaScope = oracle.GlobalTxnScope
+	req.TxnScope = oracle.GlobalTxnScope
+	req.EnableStaleRead()
+	req.ReplicaReadType = kv.ReplicaReadFollower
+
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+	bo := retry.NewBackoffer(ctx, -1)
+	s.Nil(err)
+	resp, _, _, err := s.regionRequestSender.SendReqCtx(bo, req, regionLoc.Region, time.Second, tikvrpc.TiKV)
+	s.Nil(err)
+	regionErr, err := resp.GetRegionError()
+	s.Nil(err)
+	s.Equal(regionErrorToLabel(regionErr), "mismatch_peer_id")
+	// return non-epoch-not-match region error and the upper layer can auto retry.
+	s.Nil(regionErr.GetEpochNotMatch())
+	// after region error returned, the region should be invalidated.
+	s.False(region.isValid())
+}