Fix hsdp_device_mesh=None when enable HSDP and HYBRID_SHARD (#402)

Co-authored-by: haozhx23 <haozhn@amazon.com>
Co-authored-by: Matthias Reso <13337103+mreso@users.noreply.github.com>

src/llama_recipes/finetuning.py

@@ -163,10 +163,9 @@ def main(**kwargs):
             wandb_run.config.update(peft_config)
         model.print_trainable_parameters()
 
-
-    hsdp_device_mesh = None
+    hsdp_device_mesh_plan = None
     if fsdp_config.hsdp and fsdp_config.sharding_strategy == ShardingStrategy.HYBRID_SHARD:
-        hsdp_device_mesh = hsdp_device_mesh(replica_group_size=fsdp_config.replica_group_size, sharding_group_size=fsdp_config.sharding_group_size)
+        hsdp_device_mesh_plan = hsdp_device_mesh(replica_group_size=fsdp_config.replica_group_size, sharding_group_size=fsdp_config.sharding_group_size)
         print("HSDP device mesh is ready")
 
     #setting up FSDP if enable_fsdp is enabled
@@ -189,7 +188,7 @@ def main(**kwargs):
             cpu_offload=CPUOffload(offload_params=True) if fsdp_config.fsdp_cpu_offload else None,
             mixed_precision=mixed_precision_policy if not fsdp_config.pure_bf16 else None,
             sharding_strategy=fsdp_config.sharding_strategy,
-            device_mesh=hsdp_device_mesh,
+            device_mesh=hsdp_device_mesh_plan,
             device_id=device_id,
             limit_all_gathers=True,
             sync_module_states=train_config.low_cpu_fsdp,