[fleet_executor] Dist model bug fixer (#39207)

paddle/fluid/distributed/fleet_executor/dist_model.cc

@@ -487,21 +487,25 @@ bool DistModel::PrepareFeedAndFetch() {
       if (feeds_.size() == 0) {
         LOG(ERROR) << "Feed ops are needed for the first pp stage.";
         return false;
+      }
+    } else {
+      if (feeds_.size() > 0) {
+        LOG(WARNING) << "Feed op is found in the non-first stage of pp.";
       } else {
-        LOG(WARNING) << "No feed ops in non-first pp stage.";
+        LOG(INFO) << "No feed ops in non-first pp stage.";
       }
-    } else if (feeds_.size() > 0) {
-      LOG(WARNING) << "Feed op is found in the non-first stage of pp.";
     }
     if (IsPPLastStage(config_)) {
       if (fetches_.size() == 0) {
-        LOG(ERROR) << "Fetch op is needed for the last pp stage.";
-        return false;
+        LOG(WARNING) << "No fetch op was found in the last pp stage. Make sure "
+                        "the result has been sent to frist pp stage.";
+      }
+    } else {
+      if (fetches_.size() > 0) {
+        LOG(WARNING) << "Fetch op is found in the non-last stage of pp.";
       } else {
-        LOG(WARNING) << "No fetch op in non-last pp stage.";
+        LOG(INFO) << "No fetch op in non-last pp stage.";
       }
-    } else if (fetches_.size() > 0) {
-      LOG(WARNING) << "Fetch op is found in the non-last stage of pp.";
     }
   }
   return true;