FIX / Quantization: Add extra validation for bnb config (#31135)

add validation for bnb config

src/transformers/utils/quantization_config.py

@@ -383,6 +383,10 @@ class BitsAndBytesConfig(QuantizationConfigMixin):
         if bnb_4bit_quant_storage is None:
             self.bnb_4bit_quant_storage = torch.uint8
         elif isinstance(bnb_4bit_quant_storage, str):
+            if bnb_4bit_quant_storage not in ["float16", "float32", "int8", "uint8", "float64", "bfloat16"]:
+                raise ValueError(
+                    "`bnb_4bit_quant_storage` must be a valid string (one of 'float16', 'float32', 'int8', 'uint8', 'float64', 'bfloat16') "
+                )
             self.bnb_4bit_quant_storage = getattr(torch, bnb_4bit_quant_storage)
         elif isinstance(bnb_4bit_quant_storage, torch.dtype):
             self.bnb_4bit_quant_storage = bnb_4bit_quant_storage

tests/quantization/bnb/test_4bit.py

@@ -303,6 +303,13 @@ class Bnb4BitTest(Base4bitTest):
         model = AutoModelForSeq2SeqLM.from_pretrained("google-t5/t5-small", load_in_4bit=True, device_map="auto")
         self.assertTrue(model.decoder.block[0].layer[2].DenseReluDense.wo.weight.dtype == torch.float32)
 
+    def test_bnb_4bit_wrong_config(self):
+        r"""
+        Test whether creating a bnb config with unsupported values leads to errors.
+        """
+        with self.assertRaises(ValueError):
+            _ = BitsAndBytesConfig(load_in_4bit=True, bnb_4bit_quant_storage="add")
+
 
 @require_bitsandbytes
 @require_accelerate