[torchao] safetensors integration (#25969)

Signed-off-by: Angel Li <liangel@meta.com>

vllm/model_executor/model_loader/default_loader.py

@@ -14,6 +14,7 @@ from transformers.utils import SAFE_WEIGHTS_INDEX_NAME
 from vllm.config import ModelConfig
 from vllm.config.load import LoadConfig
 from vllm.logger import init_logger
+from vllm.model_executor.layers.quantization.torchao import torchao_version_at_least
 from vllm.model_executor.model_loader.base_loader import BaseModelLoader
 from vllm.model_executor.model_loader.weight_utils import (
     download_safetensors_index_file_from_hf,
@@ -272,6 +273,10 @@ class DefaultModelLoader(BaseModelLoader):
         )
 
     def load_weights(self, model: nn.Module, model_config: ModelConfig) -> None:
+        if model_config.quantization == "torchao" and torchao_version_at_least(
+            "0.14.0"
+        ):
+            self.load_config.safetensors_load_strategy = "torchao"
         weights_to_load = {name for name, _ in model.named_parameters()}
 
         # if we don't have `model.weight_metadata_and_attr_saved` defined and