add check for input channels and Attr(groups), test=develop (#21095)

paddle/fluid/operators/maxout_op.cc

@@ -82,6 +82,14 @@ class MaxOutOp : public framework::OperatorWithKernel {
     // check groups > 1
     PADDLE_ENFORCE_GT(groups, 1,
                       "Attr(groups) of Op(maxout) should be larger than 1.");
+    PADDLE_ENFORCE_EQ(
+        in_x_dims[axis] % groups, 0,
+        "ValueError: The number of input channels for Op(maxout) "
+        "should be divisible by Attr(groups). But received: the "
+        "input's channels is [%d], the shape of input is [%s], "
+        "the Attr(groups) is [%d], the Attr(axis) is [%d]. The "
+        "error may come from wrong Attr(groups) or Attr(axis) setting.",
+        in_x_dims[axis], in_x_dims, groups, axis);
     std::vector<int64_t> output_shape(
         {in_x_dims[0], in_x_dims[1], in_x_dims[2], in_x_dims[3]});
     output_shape[axis] = in_x_dims[axis] / groups;