[Bugfix] Fix fully sharded LoRAs with Mixtral (#11390)

Signed-off-by: Jason Greene <jason.greene@redhat.com>

tests/lora/test_mixtral.py

@@ -62,8 +62,9 @@ def test_mixtral_lora(mixtral_lora_files, tp_size):
 
 
 @pytest.mark.parametrize("tp_size", [4])
+@pytest.mark.parametrize("fully_shard", [True, False])
 def test_mixtral_lora_all_target_modules(mixtral_lora_files_all_target_modules,
-                                         tp_size):
+                                         tp_size, fully_shard):
     """This LoRA model has all supported Mixtral target modules"""
 
     if torch.cuda.device_count() < tp_size:
@@ -82,6 +83,7 @@ def test_mixtral_lora_all_target_modules(mixtral_lora_files_all_target_modules,
         max_loras=4,
         distributed_executor_backend="ray",
         tensor_parallel_size=tp_size,
+        fully_sharded_loras=fully_shard,
         max_lora_rank=32,
     )
 

vllm/lora/layers.py

@@ -425,8 +425,9 @@ class ReplicatedLinearWithLoRA(BaseLinearLayerWithLoRA):
                        if self.base_layer.skip_bias_add else None)
         return output, output_bias
 
+    # ReplicatedLinear should always be replaced, regardless of the fully
+    # sharded LoRAs setting, because it is, by definition, copied per GPU.
     @classmethod
-    @_not_fully_sharded_can_replace
     def can_replace_layer(
         cls,
         source_layer: nn.Module,