Llama4 linearized (#2502)

* llama4 support for linearized experts

* clean up fsdp2 sharding to prevent hang

* add yaml config

* cleanup example [skip ci]

examples/llama-4/scout-qlora-fsdp1.yaml

@@ -0,0 +1,93 @@
+base_model: axolotl-quants/Llama-4-Scout-17B-16E-Linearized-bnb-nf4-bf16
+model_type: Llama4ForConditionalGeneration
+  # Automatically upload checkpoint and final model to HF
+  # hub_model_id: username/custom_model_name
+
+strict: false
+
+# torch_compile: true
+plugins:
+  - axolotl.integrations.liger.LigerPlugin
+
+liger_glu_activation: true
+liger_rms_norm: true
+liger_layer_norm: true
+
+llama4_linearized_experts: true
+load_in_4bit: true
+adapter: qlora
+lora_r: 32
+lora_alpha: 64
+lora_target_modules:
+  - self_attn.q_proj
+  - self_attn.k_proj
+  - self_attn.v_proj
+  - self_attn.o_proj
+  - shared_expert.gate_proj
+  - shared_expert.up_proj
+  - shared_expert.down_proj
+    # - experts.gate_projs.[0-9]+$
+    # - experts.up_projs.[0-9]+$
+    # - experts.down_projs.[0-9]+$
+lora_modules_to_save:
+  - lm_head
+  - embed_tokens
+
+chat_template: llama4
+datasets:
+  - path: mlabonne/FineTome-100k
+    type: chat_template
+    split: train[:20%]
+    field_messages: conversations
+    message_property_mappings:
+      role: from
+      content: value
+
+dataset_prepared_path: last_run_prepared
+val_set_size: 0.0
+output_dir: ./outputs/out
+
+sequence_len: 4096
+sample_packing: true
+pad_to_sequence_len: true
+
+wandb_project:
+wandb_entity:
+wandb_watch:
+wandb_name:
+wandb_log_model:
+
+gradient_accumulation_steps: 1
+micro_batch_size: 1
+num_epochs: 1
+optimizer: adamw_torch_fused
+lr_scheduler: cosine
+learning_rate: 2e-5
+
+bf16: true
+tf32: true
+
+logging_steps: 1
+flash_attention: true
+
+warmup_steps: 100
+evals_per_epoch: 1
+saves_per_epoch: 1
+weight_decay: 0.0
+fsdp:
+  - auto_wrap
+  - full_shard
+fsdp_config:
+  fsdp_transformer_layer_cls_to_wrap: Llama4TextDecoderLayer
+  fsdp_limit_all_gathers: true
+  fsdp_sync_module_states: true
+  fsdp_offload_params: true
+  fsdp_use_orig_params: false
+  fsdp_cpu_ram_efficient_loading: true
+  fsdp_auto_wrap_policy: TRANSFORMER_BASED_WRAP
+  fsdp_state_dict_type: FULL_STATE_DICT
+  fsdp_sharding_strategy: FULL_SHARD
+  fsdp_activation_checkpointing: true
+special_tokens:
+  pad_token: <|finetune_right_pad_id|>
+  eos_token: <|eot|>

requirements-dev.txt

@@ -4,3 +4,5 @@ mypy
 types-requests
 quartodoc
 jupyter
+blobfile
+tiktoken

src/axolotl/monkeypatch/accelerate/fsdp2.py

@@ -0,0 +1,63 @@
+"""
+monkeypatch for accelerate fsdp2 fix when modifying ordereddict during interation
+"""
+
+import logging
+import sys
+
+import torch
+
+LOG = logging.getLogger(__name__)
+
+
+def fsdp2_load_full_state_dict(accelerator, model: torch.nn.Module, full_sd: dict):
+    """
+    Loads the full state dict (could be only on rank 0) into the sharded model. This is done by broadcasting the
+    parameters from rank 0 to all other ranks. This function modifies the model in-place.
+
+    Args:
+        accelerator (`Accelerator`): The accelerator instance
+        model (`torch.nn.Module`): The model to load the state dict into
+        full_sd (`dict`): The full state dict to load, can only be on rank 0
+    """
+    import torch.distributed as dist
+    from torch.distributed.tensor import distribute_tensor
+
+    LOG.info("Broadcasting full state dict to all ranks...")
+    sharded_sd = model.state_dict()
+    param_names = sorted(sharded_sd.keys())
+    for param_name in param_names:
+        mesh = sharded_sd[param_name].device_mesh
+        if accelerator.is_main_process:
+            # Use the corresponding tensor from full_sd (assuming the key exists in full_sd)
+            full_param = full_sd[param_name].detach().cuda()
+            dist.broadcast(full_param, src=0, group=mesh.get_group())
+            sharded_tensor = distribute_tensor(
+                full_param, mesh, sharded_sd[param_name].placements
+            )
+            sharded_sd[param_name] = sharded_tensor
+        else:
+            # Prepare a tensor of matching shape and dtype
+            full_tensor = torch.empty(
+                sharded_sd[param_name].size(),
+                device="cuda",
+                dtype=sharded_sd[param_name].dtype,
+            )
+            dist.broadcast(full_tensor, src=0, group=mesh.get_group())
+            sharded_tensor = distribute_tensor(
+                full_tensor, mesh, sharded_sd[param_name].placements
+            )
+            sharded_sd[param_name] = sharded_tensor
+
+    model.load_state_dict(sharded_sd)
+
+
+def patch_accelerate_fsdp_utils():
+    from accelerate.utils import fsdp_utils
+
+    fsdp_utils.fsdp2_load_full_state_dict = fsdp2_load_full_state_dict
+    setattr(
+        sys.modules["accelerate.utils.fsdp_utils"],
+        "fsdp2_load_full_state_dict",
+        fsdp2_load_full_state_dict,
+    )

src/axolotl/monkeypatch/lora_kernels.py

@@ -4,7 +4,7 @@ import importlib
 import inspect
 import logging
 import types
-from typing import Type
+from typing import Generator, Tuple, Type
 
 import torch
 from accelerate.logging import get_logger
@@ -200,6 +200,46 @@ def patch_self_attn_lora(cfg: DictDefault):
     )
 
 
+def find_self_attn_in_layer(
+    layer: nn.Module,
+) -> Generator[Tuple[nn.Module], None, None]:
+    # general case of most models
+    if hasattr(layer, "self_attn"):
+        if all(
+            hasattr(layer.self_attn, proj)
+            for proj in ["q_proj", "k_proj", "v_proj", "o_proj"]
+        ):
+            yield layer.self_attn
+
+
+def find_mlp_in_layer(
+    layer: nn.Module,
+) -> Generator[Tuple[nn.Module, nn.Module, nn.Module, nn.Module], None, None]:
+    # general case of most models
+    if hasattr(layer, "mlp"):
+        if all(
+            hasattr(layer.mlp, proj) for proj in ["gate_proj", "up_proj", "down_proj"]
+        ):
+            yield layer.mlp.gate_proj, layer.mlp.up_proj, layer.mlp.down_proj, layer.mlp
+    # llama4 linearized experts
+    if hasattr(layer, "feedforward") and hasattr(layer.feedforward, "shared_expert"):
+        mlp = layer.feedforward.shared_expert
+        yield mlp.gate_proj, mlp.up_proj, mlp.down_proj, mlp
+    if hasattr(layer, "feedforward") and hasattr(layer.feedforward, "experts"):
+        if all(
+            hasattr(layer.feedforward.experts, proj)
+            for proj in ["gate_projs", "up_projs", "down_projs"]
+        ):
+            for gate_proj, up_proj, down_proj in zip(
+                layer.feedforward.experts.gate_projs,
+                layer.feedforward.experts.up_projs,
+                layer.feedforward.experts.down_projs,
+            ):
+                yield gate_proj, up_proj, down_proj, FakeMLP(
+                    gate_proj, up_proj, down_proj
+                )
+
+
 def apply_lora_kernel_patches(
     model: PeftModelForCausalLM, cfg: DictDefault
 ) -> PeftModelForCausalLM:
@@ -286,74 +326,82 @@ def apply_lora_kernel_patches(
     for layer in layers:
         # Add QKV, O fallback implementations to start
         # These will be overwritten later (if some conditions apply)
-        layer.self_attn.apply_qkv = types.MethodType(
-            original_apply_qkv, layer.self_attn
-        )
-        layer.self_attn.apply_o = types.MethodType(original_apply_o, layer.self_attn)
+        for self_attn in find_self_attn_in_layer(layer):
+            self_attn.apply_qkv = types.MethodType(original_apply_qkv, self_attn)
+            self_attn.apply_o = types.MethodType(original_apply_o, self_attn)
 
-        if cfg.lora_mlp_kernel:
-            # MLP patching
-            gate_proj = layer.mlp.gate_proj
-            up_proj = layer.mlp.up_proj
-            down_proj = layer.mlp.down_proj
+            if cfg.lora_qkv_kernel:
+                # Query, key, value patching
+                layer_modules = [
+                    getattr(self_attn, linear_proj)
+                    for linear_proj in ["q_proj", "k_proj", "v_proj"]
+                ]
+                can_patch_qkv = all(
+                    hasattr(module, "lora_A")
+                    and getattr(module, "base_layer", module).bias is None
+                    and len(getattr(module, "lora_magnitude_vector", []) or []) == 0
+                    for module in layer_modules
+                )
 
-            can_patch_mlp = all(
-                hasattr(proj, "lora_A")
-                and getattr(proj, "base_layer", proj).bias is None
-                and len(getattr(proj, "lora_magnitude_vector", []) or []) == 0
-                for proj in (gate_proj, up_proj, down_proj)
-            )
+                if can_patch_qkv:
+                    # Add optimized implementation
+                    self_attn.apply_qkv = types.MethodType(apply_lora_qkv, self_attn)
+                else:
+                    LOG.warning_once(
+                        "Cannot patch some attention QKV projections - requires LoRA adapters with no bias"
+                    )
+            if cfg.lora_o_kernel:
+                # Output patching
+                layer_modules = [
+                    getattr(self_attn, linear_proj) for linear_proj in ["o_proj"]
+                ]
+                can_patch_o = all(
+                    hasattr(module, "lora_A")
+                    and getattr(module, "base_layer", module).bias is None
+                    and len(getattr(module, "lora_magnitude_vector", []) or []) == 0
+                    for module in layer_modules
+                )
 
-            if can_patch_mlp:
-                apply_fn = APPLY_FN_MAPPING[activation]
-                layer.mlp.forward = types.MethodType(apply_fn, layer.mlp)
-            else:
-                LOG.warning_once(
-                    "Cannot patch some MLP layers - requires LoRA adapters with no bias"
+                if can_patch_o:
+                    self_attn.apply_o = types.MethodType(apply_lora_o, self_attn)
+                else:
+                    LOG.warning_once(
+                        "Cannot patch some attention output projection - requires LoRA adapters with no bias"
+                    )
+        for gate_proj, up_proj, down_proj, mlp in find_mlp_in_layer(layer):
+            if cfg.lora_mlp_kernel:
+                # MLP patching
+                can_patch_mlp = all(
+                    hasattr(proj, "lora_A")
+                    and getattr(proj, "base_layer", proj).bias is None
+                    and len(getattr(proj, "lora_magnitude_vector", []) or []) == 0
+                    for proj in (gate_proj, up_proj, down_proj)
                 )
-        if cfg.lora_qkv_kernel:
-            # Query, key, value patching
-            layer_modules = [
-                getattr(layer.self_attn, linear_proj)
-                for linear_proj in ["q_proj", "k_proj", "v_proj"]
-            ]
-            can_patch_qkv = all(
-                hasattr(module, "lora_A")
-                and getattr(module, "base_layer", module).bias is None
-                and len(getattr(module, "lora_magnitude_vector", []) or []) == 0
-                for module in layer_modules
-            )
 
-            if can_patch_qkv:
-                # Add optimized implementation
-                layer.self_attn.apply_qkv = types.MethodType(
-                    apply_lora_qkv, layer.self_attn
-                )
-            else:
-                LOG.warning_once(
-                    "Cannot patch some attention QKV projections - requires LoRA adapters with no bias"
-                )
-        if cfg.lora_o_kernel:
-            # Output patching
-            layer_modules = [
-                getattr(layer.self_attn, linear_proj) for linear_proj in ["o_proj"]
-            ]
-            can_patch_o = all(
-                hasattr(module, "lora_A")
-                and getattr(module, "base_layer", module).bias is None
-                and len(getattr(module, "lora_magnitude_vector", []) or []) == 0
-                for module in layer_modules
-            )
-
-            if can_patch_o:
-                layer.self_attn.apply_o = types.MethodType(
-                    apply_lora_o, layer.self_attn
-                )
-            else:
-                LOG.warning_once(
-                    "Cannot patch some attention output projection - requires LoRA adapters with no bias"
-                )
+                if can_patch_mlp:
+                    apply_fn = APPLY_FN_MAPPING[activation]
+                    layer.mlp.forward = types.MethodType(apply_fn, mlp)
+                else:
+                    LOG.warning_once(
+                        "Cannot patch some MLP layers - requires LoRA adapters with no bias"
+                    )
 
     LOG.setLevel(original_level)
 
     return model
+
+
+class FakeMLP(nn.Module):
+    """
+    placeholder MLP for triton patching
+    """
+
+    gate_proj: nn.Linear
+    up_proj: nn.Linear
+    down_proj: nn.Linear
+
+    def __init__(self, gate_proj, up_proj, down_proj):
+        super().__init__()
+        self.gate_proj = gate_proj
+        self.up_proj = up_proj
+        self.down_proj = down_proj

src/axolotl/monkeypatch/models/llama4/modeling.py

@@ -0,0 +1,101 @@
+"""
+Modified Llama-4 text experts modeling for linearized experts for improved LoRA support
+"""
+
+import sys
+
+import torch
+from torch import nn
+from transformers import Llama4Config
+from transformers.activations import ACT2FN
+
+
+class Llama4TextExperts(nn.Module):
+    """
+    Modified Llama-4 text experts modeling for linearized experts
+    """
+
+    def __init__(self, config: Llama4Config):
+        super().__init__()
+        self.num_experts = config.num_local_experts
+        self.intermediate_size = config.intermediate_size
+        self.hidden_size = config.hidden_size
+        self.expert_dim = self.intermediate_size
+
+        # Replace fused gate_up_proj with separate Linear modules
+        self.gate_projs = nn.ModuleList(
+            [
+                nn.Linear(self.hidden_size, self.expert_dim, bias=False)
+                for _ in range(self.num_experts)
+            ]
+        )
+
+        self.up_projs = nn.ModuleList(
+            [
+                nn.Linear(self.hidden_size, self.expert_dim, bias=False)
+                for _ in range(self.num_experts)
+            ]
+        )
+
+        # Replace down_proj Parameter with Linear modules
+        self.down_projs = nn.ModuleList(
+            [
+                nn.Linear(self.expert_dim, self.hidden_size, bias=False)
+                for _ in range(self.num_experts)
+            ]
+        )
+
+        self.act_fn = ACT2FN[config.hidden_act]
+
+    def forward(self, hidden_states: torch.Tensor) -> torch.Tensor:
+        """
+        Forward method using separate Linear layers for each expert.
+
+        Args:
+            hidden_states (torch.Tensor): (num_experts * batch_size, hidden_size)
+                The input should be organized by expert
+
+        Returns:
+            torch.Tensor: (num_experts * batch_size, hidden_size)
+        """
+        # Reshape to separate by expert
+        hidden_states = hidden_states.view(self.num_experts, -1, self.hidden_size)
+        # batch_size_per_expert = hidden_states.size(1)
+
+        # Initialize output tensor
+        next_states = torch.zeros_like(hidden_states)
+
+        # Process each expert separately
+        for i in range(self.num_experts):
+            # Get input for this expert
+            expert_input = hidden_states[
+                i
+            ]  # Shape: (batch_size_per_expert, hidden_size)
+
+            # Apply gate and up projections
+            gate = self.gate_projs[i](
+                expert_input
+            )  # Shape: (batch_size_per_expert, expert_dim)
+            up = self.up_projs[i](
+                expert_input
+            )  # Shape: (batch_size_per_expert, expert_dim)
+
+            # Apply activation and down projection
+            next_states[i] = self.down_projs[i](up * self.act_fn(gate))
+
+        # Flatten back to original shape
+        return next_states.view(-1, self.hidden_size)
+
+
+def patch_llama4_linearized_modeling():
+    """
+    Patch Llama4TextExperts to use separate Linear layers for each expert.
+    """
+    from transformers.models.llama4 import modeling_llama4
+
+    modeling_llama4.Llama4TextExperts = Llama4TextExperts
+    setattr(
+        sys.modules["transformers.models.llama4"],
+        "Llama4TextExperts",
+        Llama4TextExperts,
+    )

src/axolotl/utils/models.py

@@ -544,8 +544,20 @@ class ModelLoader:
         self.auto_model_loader = AutoModelForCausalLM  # pylint: disable=invalid-name
 
     def apply_patches(self) -> None:
+        if self.cfg.fsdp_config and str(self.cfg.fsdp_config.fsdp_version) == "2":
+            from axolotl.monkeypatch.accelerate.fsdp2 import patch_accelerate_fsdp_utils
+
+            patch_accelerate_fsdp_utils()
         # patch gemma3 conditional generation forward before loading plugins
         # as it could be overridden by plugins
+        if self.cfg.model_config_type == "llama4":
+            if self.cfg.llama4_linearized_experts:
+                from axolotl.monkeypatch.models.llama4.modeling import (
+                    patch_llama4_linearized_modeling,
+                )
+
+                patch_llama4_linearized_modeling()
+
         if self.cfg.model_config_type == "gemma3":
             from axolotl.monkeypatch.gemma3 import (
                 patch_gemma3conditionalgeneration_forward,

src/axolotl/utils/schemas/config.py

@@ -245,6 +245,8 @@ class AxolotlInputConfig(
     lora_qkv_kernel: bool | None = None
     lora_o_kernel: bool | None = None
 
+    llama4_linearized_experts: bool | None = None
+
     deepspeed: str | dict[str, Any] | None = None
     fsdp: list[str] | None = None
     fsdp_config: dict[str, Any] | None = None