"tensor mutable data"

paddle/operators/mul_op.h

@@ -51,9 +51,11 @@ class MulGradKernel : public framework::OpKernel {
 
     auto* dX = ctx.Output<Tensor>(framework::GradVarName("X"));
     auto* dY = ctx.Output<Tensor>(framework::GradVarName("Y"));
+    dX->mutable_data<T>(ctx.GetPlace());
+    dY->mutable_data<T>(ctx.GetPlace());
     auto* device_context =
         const_cast<platform::DeviceContext*>(ctx.device_context_);
-    // dX = dOut' * Y. dX: M x K, dOut : M x N, Y : K x N
+    // dX = dOut * Y'. dX: M x K, dOut : M x N, Y : K x N
     math::matmul<Place, T>(*dOut, false, *Y, true, 1, dX, 0, device_context);
     // dY = X' * dOut. dY: K x N, dOut : M x N, X : M x K
     math::matmul<Place, T>(*X, true, *dOut, false, 1, dY, 0, device_context);