[data] specify position_ids in PackedSupervisedDatasetProcessor for neat_packing (#7318)

* use position_ids for neat_packing with fa2

* revert fa2 changes

Author: BlackWingedKing

src/llamafactory/data/processor/supervised.py

@@ -165,7 +165,7 @@ def preprocess_dataset(self, examples: dict[str, list[Any]]) -> dict[str, list[A
         knapsacks = greedy_knapsack(lengths, self.data_args.cutoff_len)
         for knapsack in knapsacks:
             packed_input_ids, packed_attention_masks, packed_labels = [], [], []
-            packed_images, packed_videos, packed_audios = [], [], []
+            packed_images, packed_videos, packed_audios, packed_position_ids = [], [], [], []
             for i, length in enumerate(knapsack):
                 index = length2indexes[length].pop()
                 packed_input_ids += batch_input_ids[index]
@@ -175,6 +175,7 @@ def preprocess_dataset(self, examples: dict[str, list[Any]]) -> dict[str, list[A
                 packed_audios += batch_audios[index]
                 if self.data_args.neat_packing:
                     packed_attention_masks += [i + 1] * len(batch_input_ids[index])  # start from 1
+                    packed_position_ids += list(range(len(batch_input_ids[index])))
                 else:
                     packed_attention_masks += [1] * len(batch_input_ids[index])
 
@@ -184,6 +185,7 @@ def preprocess_dataset(self, examples: dict[str, list[Any]]) -> dict[str, list[A
                 packed_labels += [IGNORE_INDEX] * pad_length
                 if self.data_args.neat_packing:
                     packed_attention_masks += [0] * pad_length
+                    packed_position_ids += [0] * pad_length
                 else:
                     packed_attention_masks += [1] * pad_length  # more efficient flash_attn
 
@@ -196,5 +198,6 @@ def preprocess_dataset(self, examples: dict[str, list[Any]]) -> dict[str, list[A
             model_inputs["images"].append(packed_images or None)
             model_inputs["videos"].append(packed_videos or None)
             model_inputs["audios"].append(packed_audios or None)
+            model_inputs["position_ids"].append(packed_position_ids or None)
 
         return model_inputs