how to freeze Pytorch layers

# View layers with model.children()
# Get params with module.parameters()

m = resnet50(pretrained=True)
_ = m.train()
for param in list(m.children())[0].parameters():
    param.requires_grad = False
_ = m.resnet50.eval() # disables dropout

Then:
optimizer = Adam(filter(lambda p: p.requires_grad, m.parameters()), lr=3e-4)