diff --git a/dnn/include/megdnn/oprs/general.h b/dnn/include/megdnn/oprs/general.h
index b327f3fc..acc4a75b 100644
--- a/dnn/include/megdnn/oprs/general.h
+++ b/dnn/include/megdnn/oprs/general.h
@@ -469,9 +469,7 @@ using Split = SplitForward;
  * large number of inputs and can handle alignment requirements. Axis is also
  * not supported.
  *
- * The offsets can be generated by gen_offsets(). The \p srcs in ParamPackSplit and
- * \p dsts in ParamPackConcat must be on CPU, and must remain valid until the
- * execution stream is synchronized.
+ * The offsets can be generated by gen_offsets().
  */
 class ParamPackConcatSplitBase : public OperatorBase {
 protected:
@@ -502,7 +500,7 @@ public:
      *                  address of i-th Tensor.
      * \param[in] offsets: with size `2 * srcs.shape[0]`.
      *                  offsets[i * 2] and offsets[i * 2 + 1] means
-     *                  the begin and the end of offset in
+     *                  the begin and the end of srcs[i]'s offsets in dst
      * \param[out] dst: output TensorND, live on cpu or gpu
      */
     virtual void exec(_megdnn_tensor_in srcs, _megdnn_tensor_in offsets,
diff --git a/src/opr/include/megbrain/opr/tensor_manip.h b/src/opr/include/megbrain/opr/tensor_manip.h
index 8dcff9da..c9d1cb39 100644
--- a/src/opr/include/megbrain/opr/tensor_manip.h
+++ b/src/opr/include/megbrain/opr/tensor_manip.h
@@ -535,6 +535,10 @@ MGB_DEFINE_OPR_CLASS(Concat, cg::SingleCNOutshapePureByInshapeOprBase) // {
 /*!
  * \brief Opr used to pack parameter, all input node must in same device, dtype
  *      and shape is not needed to be same
+ * \param offsets: size of 2 * inputs.size()
+ *      offsets[i * 2] and offsets[i * 2 + 1] means
+ *      the begin and the end of inputs[i]'s offsets in output
+ * \param offsets_val: offsets value on cpu
  */
 MGB_DEFINE_OPR_CLASS(ParamPackConcat, cg::SingleCNOperatorNodeBase) // {
     //! input pointer buffer
@@ -577,6 +581,11 @@ public:
 
 /*!
  * \brief Opr used to split parameter
+ * \param offsets: size of 2 * outputs.size()
+ *      offsets[i * 2] and offsets[i * 2 + 1] means
+ *      the begin and the end of output[i]'s offsets in input
+ * \param offsets_val: offsets value on cpu
+ * \param shapes: shape of each output
  */
 MGB_DEFINE_OPR_CLASS(ParamPackSplit, cg::SingleCNOperatorNodeBase) // {
     TensorShapeArray m_shapes;