RuntimeError: Creating MTGP constants failed. at /opt/conda/conda-bld/pytorch_1549287501208/work/aten/src/THC/THCTensorRandom.cu:35
Author: drjosephliu
Pull request: no

# 🐛 Bug

## Information

Model I am using (Bert, XLNet ...): BertForSequenceClassification

Language I am using the model on (English, Chinese ...): English

The problem arises when using:
* [ ] the official example scripts: (give details below)
* [x ] my own modified scripts: (give details below)

The tasks I am working on is:
* [ ] an official GLUE/SQUaD task: (give the name)
* [x ] my own task or dataset: (give details below)

## To reproduce

Steps to reproduce the behavior:

I am performing multi-class (50 classes) classification on the Project Gutenberg dataset. The max text length is 1620 so I set max length at 2048. I'm also padding the text with 0s.

```
MAX_LEN = 2048
def get_encodings(texts):
    token_ids = []
    attention_masks = []
    for text in texts:
        token_id = tokenizer.encode(text, add_special_tokens=True, max_length=2048)
        token_ids.append(token_id)
    return token_ids

def pad_encodings(encodings):
    return pad_sequences(encodings, maxlen=MAX_LEN, dtype="long", 
                          value=0, truncating="post", padding="post")

def get_attention_masks(padded_encodings):
    attention_masks = []
    for encoding in padded_encodings:
        attention_mask = [int(token_id > 0) for token_id in encoding]
        attention_masks.append(attention_mask)
    return attention_masks

X_train = torch.tensor(train_encodings)
y_train = torch.tensor(train_df.author_id.values)
train_masks = torch.tensor(train_attention_masks)

X_test = torch.tensor(test_encodings)
y_test = torch.tensor(test_df.author_id.values)
test_masks = torch.tensor(test_attention_masks)

batch_size = 32

# Create the DataLoader for our training set.
train_data = TensorDataset(X_train, train_masks, y_train)
train_sampler = RandomSampler(train_data)
train_dataloader = DataLoader(train_data, sampler=train_sampler, batch_size=batch_size)

validation_data = TensorDataset(X_test, test_masks, y_test)
validation_sampler = SequentialSampler(validation_data)
validation_dataloader = DataLoader(validation_data, sampler=validation_sampler, batch_size=batch_size)
```

My model is setup like so:

```
model = BertForSequenceClassification.from_pretrained(
    "bert-base-uncased", 
    num_labels = 50, 
    output_attentions = False, 
    output_hidden_states = False, 
)
```

During training however, the line indicated below is throwing the error:

```
for step, batch in enumerate(train_dataloader):

        b_texts = batch[0].to(device)
        b_attention_masks = batch[1].to(device)
        b_authors = batch[2].to(device) <---- ERROR
```

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## Expected behavior

<!-- A clear and concise description of what you would expect to happen. -->

## Environment info
<!-- You can run the command `transformers-cli env` and copy-and-paste its output below.
     Don't forget to fill out the missing fields in that output! -->
     
- `transformers` version: 2.8.0
- Platform: Ubuntu 16.04
- Python version: 1.0.0
- PyTorch version (GPU?):
- Tensorflow version (GPU?): 2.1.0
- Using GPU in script?:  Yes. P4000
- Using distributed or parallel set-up in script?: No


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