--- a
+++ b/mmseg/ops/wrappers.py
@@ -0,0 +1,51 @@
+# Copyright (c) OpenMMLab. All rights reserved.
+import warnings
+
+import torch.nn as nn
+import torch.nn.functional as F
+
+
+def resize(input,
+           size=None,
+           scale_factor=None,
+           mode='nearest',
+           align_corners=None,
+           warning=True):
+    if warning:
+        if size is not None and align_corners:
+            input_h, input_w = tuple(int(x) for x in input.shape[2:])
+            output_h, output_w = tuple(int(x) for x in size)
+            if output_h > input_h or output_w > output_h:
+                if ((output_h > 1 and output_w > 1 and input_h > 1
+                     and input_w > 1) and (output_h - 1) % (input_h - 1)
+                        and (output_w - 1) % (input_w - 1)):
+                    warnings.warn(
+                        f'When align_corners={align_corners}, '
+                        'the output would more aligned if '
+                        f'input size {(input_h, input_w)} is `x+1` and '
+                        f'out size {(output_h, output_w)} is `nx+1`')
+    return F.interpolate(input, size, scale_factor, mode, align_corners)
+
+
+class Upsample(nn.Module):
+
+    def __init__(self,
+                 size=None,
+                 scale_factor=None,
+                 mode='nearest',
+                 align_corners=None):
+        super(Upsample, self).__init__()
+        self.size = size
+        if isinstance(scale_factor, tuple):
+            self.scale_factor = tuple(float(factor) for factor in scale_factor)
+        else:
+            self.scale_factor = float(scale_factor) if scale_factor else None
+        self.mode = mode
+        self.align_corners = align_corners
+
+    def forward(self, x):
+        if not self.size:
+            size = [int(t * self.scale_factor) for t in x.shape[-2:]]
+        else:
+            size = self.size
+        return resize(x, size, None, self.mode, self.align_corners)