[Bug Fix] Fix A Bug Related to GroupRevRes (#4181)

Co-authored-by: Minjie Wang <wmjlyjemaine@gmail.com>
Co-authored-by: Xin Yao <xiny@nvidia.com>

python/dgl/nn/pytorch/conv/grouprevres.py

@@ -72,7 +72,8 @@ class InvertibleCheckpoint(torch.autograd.Function):
             detached_inputs = tuple(detached_inputs)
             temp_output = ctx.fn(*detached_inputs)
 
-        filtered_detached_inputs = tuple(filter(lambda x: x.requires_grad, detached_inputs))
+        filtered_detached_inputs = tuple(filter(lambda x: getattr(x, 'requires_grad', False),
+                                                detached_inputs))
         gradients = torch.autograd.grad(outputs=(temp_output,),
                                         inputs=filtered_detached_inputs + ctx.weights,
                                         grad_outputs=grad_outputs)

tests/pytorch/test_nn.py

@@ -1473,7 +1473,8 @@ def test_group_rev_res(idtype):
     h = th.randn(num_nodes, feats).to(dev)
     conv = nn.GraphConv(feats // groups, feats // groups)
     model = nn.GroupRevRes(conv, groups).to(dev)
-    model(g, h)
+    result = model(g, h)
+    result.sum().backward()
 
 @pytest.mark.parametrize('in_size', [16, 32])
 @pytest.mark.parametrize('hidden_size', [16, 32])