Merge pull request #12964 from sneaxiy/fix_concat_sync

Fix concat bug

paddle/fluid/operators/math/concat.cu

@@ -177,6 +177,9 @@ class ConcatFunctor<platform::CUDADeviceContext, T> {
           dev_ins_data, dev_ins_col_data, static_cast<int>(inputs_col.size()),
           out_row, out_col, output->data<T>());
     }
+    // Wait() must be called because `inputs_data` may be destructed before
+    // kernel ends
+    context.Wait();
   }
 };
 
@@ -252,6 +255,9 @@ class ConcatGradFunctor<platform::CUDADeviceContext, T> {
           input.data<T>(), in_row, in_col, dev_outs_col_data,
           static_cast<int>(outputs_cols.size()), dev_out_gpu_data);
     }
+    // Wait() must be called because `outputs_data` may be destructed before
+    // kernel ends
+    context.Wait();
   }
 };