fix for pytorch < 1.6 (#6300)

src/transformers/modeling_reformer.py

@@ -1400,7 +1400,7 @@ class ReformerLayer(nn.Module):
 
         # randomize seeds
         # use cuda generator if available
-        if len(torch.cuda.default_generators) > 0:
+        if hasattr(torch.cuda, "default_generators") and len(torch.cuda.default_generators) > 0:
             # GPU
             device_idx = torch.cuda.current_device()
             self.attention_seed = torch.cuda.default_generators[device_idx].seed()
@@ -1420,7 +1420,7 @@ class ReformerLayer(nn.Module):
         """
         # randomize seeds
         # use cuda generator if available
-        if len(torch.cuda.default_generators) > 0:
+        if hasattr(torch.cuda, "default_generators") and len(torch.cuda.default_generators) > 0:
             # GPU
             device_idx = torch.cuda.current_device()
             self.feed_forward_seed = torch.cuda.default_generators[device_idx].seed()