5.51 GiB already allocated; 417.00 MiB free; 5.53 GiB reserved in total by PyTorch CUDA out of memory
I am not sure why running this cell throws CUDA out of memory error and how I could fix it? Everytime I have to do a kill -9 PID from the list of $ nvidi-smi jupyter notebook from which this cell is being run. And still after a fresh start I have the same problem.
#torch.autograd.set_detect_anomaly(True)
network = Network()
network.cuda()    

criterion = nn.MSELoss()
optimizer = optim.Adam(network.parameters(), lr=0.0001)

loss_min = np.inf
num_epochs = 10

start_time = time.time()
for epoch in range(1,num_epochs+1):
    
    loss_train = 0
    loss_test = 0
    running_loss = 0
    
    
    network.train()
    print('size of train loader is: ', len(train_loader))

    for step in range(1,len(train_loader)+1):
    
        ##images, landmarks = next(iter(train_loader))
        ##print(type(images))
        
        batch = next(iter(train_loader))
        images, landmarks = batch['image'], batch['landmarks']
        images = images.permute(0,3,1,2)
        
        images = images.cuda()
        
        #RuntimeError: Given groups=1, weight of size [64, 3, 7, 7], expected input[64, 600, 800, 3] to have 3 channels, but got 600 channels instead
    
        
    
        landmarks = landmarks.view(landmarks.size(0),-1).cuda() 
        
        print('images shape: ', images.shape)
        print('landmarks shape: ', landmarks.shape)
        
        
        ##images = torchvision.transforms.Normalize(images)
        ##landmarks = torchvision.transforms.Normalize(landmarks)
        
        predictions = network(images)
        
        # clear all the gradients before calculating them
        optimizer.zero_grad()
        
        # find the loss for the current step
        loss_train_step = criterion(predictions.float(), landmarks.float())
        
        print(&quot;type(loss_train_step) is: &quot;, type(loss_train_step))
        
        print(&quot;loss_train_step.dtype is: &quot;,loss_train_step.dtype)
        
        ##loss_train_step = loss_train_step.to(torch.float32)
        
        # calculate the gradients
        loss_train_step.backward()
        
        # update the parameters
        optimizer.step()
        
        loss_train += loss_train_step.item()
        running_loss = loss_train/step
        
        print_overwrite(step, len(train_loader), running_loss, 'train')
        
    network.eval() 
    with torch.no_grad():
        
        for step in range(1,len(test_loader)+1):
            
            batch = next(iter(train_loader))
            images, landmarks = batch['image'], batch['landmarks']        
            images = images.cuda()
            landmarks = landmarks.view(landmarks.size(0),-1).cuda()
        
            predictions = network(images)

            # find the loss for the current step
            loss_test_step = criterion(predictions, landmarks)

            loss_test += loss_test_step.item()
            running_loss = loss_test/step

            print_overwrite(step, len(test_loader), running_loss, 'Testing')
    
    loss_train /= len(train_loader)
    loss_test /= len(test_loader)
    
    print('\n--------------------------------------------------')
    print('Epoch: {}  Train Loss: {:.4f}  Test Loss: {:.4f}'.format(epoch, loss_train, loss_test))
    print('--------------------------------------------------')
    
    if loss_test &lt; loss_min:
        loss_min = loss_test
        torch.save(network.state_dict(), '../moth_landmarks.pth') 
        print(&quot;\nMinimum Test Loss of {:.4f} at epoch {}/{}&quot;.format(loss_min, epoch, num_epochs))
        print('Model Saved\n')
     
print('Training Complete')
print(&quot;Total Elapsed Time : {} s&quot;.format(time.time()-start_time))

The complete log is:
size of train loader is:  12
images shape:  torch.Size([64, 3, 600, 800])
landmarks shape:  torch.Size([64, 8])

---------------------------------------------------------------------------
RuntimeError                              Traceback (most recent call last)
&lt;ipython-input-18-efa8f1a4056e&gt; in &lt;module&gt;
     44         ##landmarks = torchvision.transforms.Normalize(landmarks)
     45 
---&gt; 46         predictions = network(images)
     47 
     48         # clear all the gradients before calculating them

~/anaconda3/lib/python3.7/site-packages/torch/nn/modules/module.py in _call_impl(self, *input, **kwargs)
    720             result = self._slow_forward(*input, **kwargs)
    721         else:
--&gt; 722             result = self.forward(*input, **kwargs)
    723         for hook in itertools.chain(
    724                 _global_forward_hooks.values(),

&lt;ipython-input-11-46116d2a7101&gt; in forward(self, x)
     10     def forward(self, x):
     11         x = x.float()
---&gt; 12         out = self.model(x)
     13         return out

~/anaconda3/lib/python3.7/site-packages/torch/nn/modules/module.py in _call_impl(self, *input, **kwargs)
    720             result = self._slow_forward(*input, **kwargs)
    721         else:
--&gt; 722             result = self.forward(*input, **kwargs)
    723         for hook in itertools.chain(
    724                 _global_forward_hooks.values(),

~/anaconda3/lib/python3.7/site-packages/torchvision/models/resnet.py in forward(self, x)
    218 
    219     def forward(self, x):
--&gt; 220         return self._forward_impl(x)
    221 
    222 

~/anaconda3/lib/python3.7/site-packages/torchvision/models/resnet.py in _forward_impl(self, x)
    206         x = self.maxpool(x)
    207 
--&gt; 208         x = self.layer1(x)
    209         x = self.layer2(x)
    210         x = self.layer3(x)

~/anaconda3/lib/python3.7/site-packages/torch/nn/modules/module.py in _call_impl(self, *input, **kwargs)
    720             result = self._slow_forward(*input, **kwargs)
    721         else:
--&gt; 722             result = self.forward(*input, **kwargs)
    723         for hook in itertools.chain(
    724                 _global_forward_hooks.values(),

~/anaconda3/lib/python3.7/site-packages/torch/nn/modules/container.py in forward(self, input)
    115     def forward(self, input):
    116         for module in self:
--&gt; 117             input = module(input)
    118         return input
    119 

~/anaconda3/lib/python3.7/site-packages/torch/nn/modules/module.py in _call_impl(self, *input, **kwargs)
    720             result = self._slow_forward(*input, **kwargs)
    721         else:
--&gt; 722             result = self.forward(*input, **kwargs)
    723         for hook in itertools.chain(
    724                 _global_forward_hooks.values(),

~/anaconda3/lib/python3.7/site-packages/torchvision/models/resnet.py in forward(self, x)
     57         identity = x
     58 
---&gt; 59         out = self.conv1(x)
     60         out = self.bn1(out)
     61         out = self.relu(out)

~/anaconda3/lib/python3.7/site-packages/torch/nn/modules/module.py in _call_impl(self, *input, **kwargs)
    720             result = self._slow_forward(*input, **kwargs)
    721         else:
--&gt; 722             result = self.forward(*input, **kwargs)
    723         for hook in itertools.chain(
    724                 _global_forward_hooks.values(),

~/anaconda3/lib/python3.7/site-packages/torch/nn/modules/conv.py in forward(self, input)
    417 
    418     def forward(self, input: Tensor) -&gt; Tensor:
--&gt; 419         return self._conv_forward(input, self.weight)
    420 
    421 class Conv3d(_ConvNd):

~/anaconda3/lib/python3.7/site-packages/torch/nn/modules/conv.py in _conv_forward(self, input, weight)
    414                             _pair(0), self.dilation, self.groups)
    415         return F.conv2d(input, weight, self.bias, self.stride,
--&gt; 416                         self.padding, self.dilation, self.groups)
    417 
    418     def forward(self, input: Tensor) -&gt; Tensor:

RuntimeError: CUDA out of memory. Tried to allocate 470.00 MiB (GPU 0; 7.80 GiB total capacity; 5.51 GiB already allocated; 417.00 MiB free; 5.53 GiB reserved in total by PyTorch)

Here's $ nvidia-smi output right after running this cell:
$ nvidia-smi
Tue Oct 13 23:14:01 2020       
+-----------------------------------------------------------------------------+
| NVIDIA-SMI 450.51.06    Driver Version: 450.51.06    CUDA Version: 11.0     |
|-------------------------------+----------------------+----------------------+
| GPU  Name        Persistence-M| Bus-Id        Disp.A | Volatile Uncorr. ECC |
| Fan  Temp  Perf  Pwr:Usage/Cap|         Memory-Usage | GPU-Util  Compute M. |
|                               |                      |               MIG M. |
|===============================+======================+======================|
|   0  GeForce RTX 2070    Off  | 00000000:01:00.0 Off |                  N/A |
| N/A   47C    P8    13W /  N/A |   7609MiB /  7982MiB |      5%      Default |
|                               |                      |                  N/A |
+-------------------------------+----------------------+----------------------+
                                                                               
+-----------------------------------------------------------------------------+
| Processes:                                                                  |
|  GPU   GI   CI        PID   Type   Process name                  GPU Memory |
|        ID   ID                                                   Usage      |
|=============================================================================|
|    0   N/A  N/A      1424      G   /usr/lib/xorg/Xorg                733MiB |
|    0   N/A  N/A      1767      G   /usr/bin/gnome-shell              426MiB |
|    0   N/A  N/A      6420      G   /usr/lib/firefox/firefox            2MiB |
|    0   N/A  N/A      6949      G   /usr/lib/firefox/firefox            2MiB |
|    0   N/A  N/A      8888      G   /usr/lib/firefox/firefox            2MiB |
|    0   N/A  N/A     10610      G   /usr/lib/firefox/firefox            2MiB |
|    0   N/A  N/A     14943      G   /usr/lib/firefox/firefox            2MiB |
|    0   N/A  N/A     16181      C   ...mona/anaconda3/bin/python     6429MiB |
+-----------------------------------------------------------------------------+

I have an NVIDIA GeForce RTX 2070 GPU.
I also switched these two lines and still no chance and still same error:
images = images.permute(0,3,1,2)
images = images.cuda()

I also checked the nvidia-smi exactly after running all the cells above this cell, and none of them are causing this CUDA out of memory error.


Changing the batch_size from 64 to 2 here solved the problem:
train_loader = torch.utils.data.DataLoader(train_dataset, batch_size=2, shuffle=True, num_workers=4)

*Thanks a lot to Sepehr Janghorbani for helping me fix this issue.
