Cuda memory continuously increases problem

Code segment is here.

class SelfAtt(nn.Module):
    def __init__(self, input_size):
        super(SelfAtt, self).__init__()
        self.input_size = input_size
        self.linear = nn.Linear(input_size, 1)
        self.linear_u = nn.Linear(input_size, input_size)
        self.linear_w = nn.Linear(input_size, input_size)

    def forward(self, x, x_mask):
        """
        x: batchsize * len1 * hidden
        :param x:
        :return: batchsize * len1 * hidden
        """
        len1 = x.size(1)

        ctemp = []
        for i in range(len1):
            x1 = x[:, i, :]
            input1 = self.linear_u(x.view(-1, self.input_size))
            input2 = self.linear_w(x1.repeat(1, len1, 1).view(-1, self.input_size))
            #input1 = x.view(-1, self.input_size)
            #input2 = x1.repeat(1, len1, 1).view(-1, self.input_size)

            hidden = F.relu(input1 + input2)  # [b * len1]
            score = self.linear(hidden).view(x.size(0), x.size(1))
            score.data.masked_fill_(x_mask.data, -float('inf'))
            alpha = F.softmax(score)
            c = alpha.unsqueeze(1).bmm(x).squeeze(1)
            ctemp.append(c)

        return torch.stack(ctemp).transpose(0, 1)

When i use this module in my network. It will rapidly cause cuda out of memory.
How can i solve this problem?