[Core] Add explicit HWR registration bypass and progress logs

Signed-off-by: Hongsheng Liu <liuhongsheng4@huawei.com>

docs/design/feature/host_weight_runtime.md

@@ -67,26 +67,6 @@ views and mapped ranges. A separate transport still decides whether to use
 registered mmap, private pinned staging, synchronous copies, or asynchronous
 H2D transfer.
 
-## Payload validation at startup
-
-Eligible diffusion loaders accept `--host-weight-runtime-validation` (or the
-`host_weight_runtime_validation` offline/stage configuration field):
-
-- `manifest_and_metadata` is the existing default. It validates identity,
-  metadata, tensor structure, and sizes, but does not detect payload-only
-  corruption.
-- `full_checksum` reads and hashes every payload on warm acquisition before
-  restoring weights. This adds startup I/O/CPU work proportional to artifact
-  bytes; it is not a per-inference check.
-
-For example, add `--host-weight-runtime-validation full_checksum` to an enabled
-HWR deployment. Preferred mode falls back to canonical loading and can publish
-a replacement after detecting corruption; required mode fails startup. Readers
-can use different validation levels in the same domain without changing artifact
-identity. Neither level authenticates an untrusted writer or prevents mutation
-after validation. Checksumming does not imply automatic recovery of a running
-service.
-
 ## Resolution behavior
 
 The loader resolves the immutable canonical source and computes the exact

docs/design/feature/offloader/distributed_layerwise_offload.md

@@ -289,6 +289,13 @@ store, tensor ownership, or H2D payload. On success, each tensor view copies
 directly into the existing rotating HBM block buffers and the two private host
 staging slots are not allocated.
 
+`--dlo-host-registration-mode` defaults to `auto`, preserving this behavior.
+Select `disabled` to bypass HWR mapping registration and use bounded host staging
+regardless of mapping size or budget. This leaves the existing pin-memory policy
+for staging buffers unchanged. The equivalent offline/stage configuration field
+is `dlo_host_registration_mode`; an explicit disable requires enabled HWR with
+no-AllGather DLO.
+
 `--dlo-host-registration-limit-gib` is an optional per-worker preflight ceiling
 over page-aligned registered bytes. Zero adds no ceiling. A disabled pinned
 memory policy, unsupported platform/capability, over-budget mapping, or fully
@@ -296,6 +303,14 @@ rolled-back registration error selects the existing two-slot staging path. A
 partial registration that cannot be rolled back aborts startup because closing
 the lease would unmap memory still owned by the platform.
 
+Automatic registration logs its entry with device and budget, then each CUDA
+region's ordinal/total and byte size before calling `cudaHostRegister`. A
+completion message follows each successful call. These identify the last
+entered boundary if progress stops; they do not impose a timeout. A synchronous
+CUDA call cannot be safely cancelled by a Python timer, and a stuck process
+still requires external supervision. The explicit disable option avoids this
+registration path; it does not repair the underlying driver hang.
+
 Direct checkpoint mmap remains unchanged and continues to use staging. It may
 require loader-owned per-block transforms, while the HWR artifact already
 contains final runtime bytes. DLO AllGather never receives an HWR final-layout

tests/config/test_omni_config.py

@@ -193,35 +193,37 @@ def test_resolve_execution_mode_rejects_unknown_execution_type():
         omni_config_module._resolve_execution_mode("unknown_execution_type")
 
 
-@pytest.mark.parametrize("validation", ["manifest_and_metadata", "full_checksum"])
-def test_hwr_validation_survives_config_projection(validation: str):
+@pytest.mark.parametrize("registration_mode", ["auto", "disabled"])
+def test_hwr_registration_policy_reaches_offloader(tmp_path: Path, registration_mode: str):
     from vllm_omni.diffusion.data import OmniDiffusionConfig
+    from vllm_omni.diffusion.offloader.base import OffloadConfig
 
-    override = StageDeployConfig(stage_id=0, host_weight_runtime_validation=validation)
-    config = _from_pipeline_key(
-        "dreamzero",
-        deploy_config_path="dreamzero_tp1_cfg2",
-        cli_overrides={"host_weight_runtime_validation": validation},
-    )
+    options = {
+        "enable_distributed_layerwise_offload": True,
+        "dlo_use_allgather": False,
+        "host_weight_runtime_mode": "preferred",
+        "host_weight_runtime_root": str(tmp_path / "unused-store"),
+        "dlo_host_registration_mode": registration_mode,
+    }
+    config = _from_pipeline_key("dreamzero", deploy_config_path="dreamzero_tp1_cfg2", cli_overrides=options)
     stage = config.stage_by_id(0)
     assert isinstance(stage, VllmOmniDiffusionStageConfig)
-    assert stage.diffusion_config.host_weight_runtime_validation == validation
-    projection = omni_config_module._DiffusionConfigProjection.from_kwargs(
-        host_weight_runtime_validation=override.host_weight_runtime_validation
-    )
-    assert projection.host_weight_runtime_validation == validation
-    assert OmniDiffusionConfig(host_weight_runtime_validation=validation).host_weight_runtime_validation == validation
-    assert omni_config_module._DiffusionConfigProjection().host_weight_runtime_validation == "manifest_and_metadata"
-    assert OmniDiffusionConfig().host_weight_runtime_validation == "manifest_and_metadata"
+    assert stage.diffusion_config.dlo_host_registration_mode == registration_mode
+    offline = OmniDiffusionConfig(**options)
+    transport = OffloadConfig.from_od_config(offline)
+    assert transport.dlo_host_registration_mode == registration_mode
+    assert transport.pin_cpu_memory
+    assert transport.dlo_host_registration_limit_gib == 0.0
+    assert not (tmp_path / "unused-store").exists()
 
 
-@pytest.mark.parametrize("validation", ["fs_verity", "unknown", None])
-def test_hwr_validation_rejects_unsupported_values(validation):
+@pytest.mark.parametrize("registration_mode", ["unknown", None, "disabled"])
+def test_hwr_registration_policy_rejects_invalid_or_ineligible_config(registration_mode):
     from vllm_omni.diffusion.data import OmniDiffusionConfig
 
     for config_class in (OmniDiffusionConfig, omni_config_module._DiffusionConfigProjection):
-        with pytest.raises(ValueError, match="host_weight_runtime_validation"):
-            config_class(host_weight_runtime_validation=validation)
+        with pytest.raises(ValueError, match="dlo_host_registration_mode"):
+            config_class(dlo_host_registration_mode=registration_mode)
 
 
 def test_from_pipeline_config_preserves_current_pipeline_config_object():

tests/diffusion/model_loader/test_diffusers_loader.py

@@ -260,78 +260,6 @@ def test_hwr_cold_publication_and_warm_restore_skip_ordinary_dit_loading(
     assert len(tuple((store_root / "source-digests-v1" / "entries").glob("*.json"))) == 1
 
 
-@pytest.mark.parametrize("validation", ["manifest_and_metadata", "full_checksum"])
-@pytest.mark.parametrize("mode", ["preferred", "required"])
-def test_hwr_loader_payload_integrity_policy(tmp_path: Path, monkeypatch, validation: str, mode: str):
-    from vllm_omni.diffusion.offloader.startup import take_offload_startup_state
-
-    canonical = tmp_path / "canonical"
-    canonical.mkdir()
-    expected = torch.arange(4, dtype=torch.float32).to(torch.bfloat16).reshape(2, 2)
-    save_file({"weight": expected}, str(canonical / "model.safetensors"))
-    root = tmp_path / "store"
-
-    def make_loader(runtime_mode: str):
-        config = _hwr_config(canonical, root, mode=runtime_mode)
-        config.host_weight_runtime_validation = validation
-        loader = DiffusersPipelineLoader(LoadConfig(), config)
-        pipeline = _HWRPipeline(canonical)
-        monkeypatch.setattr(loader, "_init_from_load_format", lambda *args, **kwargs: pipeline)
-        return loader, pipeline
-
-    def close_plan(pipeline):
-        state = take_offload_startup_state(pipeline)
-        if state is not None and state.host_weight_plan is not None:
-            carrier = state.host_weight_plan.lease_carrier
-            if carrier is not None:
-                carrier.close()
-
-    cold_loader, cold = make_loader("preferred")
-    cold_loader.load_model(load_device="cpu", device=torch.device("cpu"))
-    assert cold.load_count == 1
-    close_plan(cold)
-    payloads = list((root / "artifacts").glob("*/*.safetensors"))
-    assert len(payloads) == 1
-    payload = payloads[0]
-    data = bytearray(payload.read_bytes())
-    data[-1] ^= 1  # Keep the header and file length valid; change only a BF16 payload byte.
-    original_mode = payload.stat().st_mode
-    payload.chmod(0o600)
-    payload.write_bytes(data)
-    payload.chmod(original_mode)
-
-    loader, pipeline = make_loader(mode)
-    try:
-        if validation == "full_checksum" and mode == "required":
-            with pytest.raises(RuntimeError, match="Host Weight Runtime resolution failed"):
-                loader.load_model(load_device="cpu", device=torch.device("cpu"))
-            assert pipeline.load_count == 0
-            assert loader.take_host_weight_plan() is None
-        else:
-            loader.load_model(load_device="cpu", device=torch.device("cpu"))
-            if validation == "manifest_and_metadata":
-                assert pipeline.load_count == 0
-                assert not torch.equal(pipeline.transformer.weight, expected)
-            else:
-                assert pipeline.load_count == 1
-                assert torch.equal(pipeline.transformer.weight, expected)
-    finally:
-        close_plan(pipeline)
-
-    if validation == "full_checksum":
-        if mode == "required":
-            assert list((root / "deny").iterdir())
-        else:
-            assert list((root / "quarantine").iterdir())
-            warm_loader, warm = make_loader(mode)
-            try:
-                warm_loader.load_model(load_device="cpu", device=torch.device("cpu"))
-                assert warm.load_count == 0
-                assert torch.equal(warm.transformer.weight, expected)
-            finally:
-                close_plan(warm)
-
-
 def test_maybe_fuse_distilled_lora_skips_when_hwr_warm_snapshot_present():
     cfg = SimpleNamespace(
         lora_backend="distill",

tests/diffusion/offloader/test_cuda_host_registration.py

@@ -124,6 +124,33 @@ def test_registration_rejects_writable_or_over_budget_before_cuda(monkeypatch: p
     assert runtime.registered == []
 
 
+@pytest.mark.parametrize("second_result", [0, 7])
+def test_registration_logs_entry_before_each_runtime_call(monkeypatch: pytest.MonkeyPatch, second_result: int) -> None:
+    runtime = _FakeRuntime([0, second_result])
+    messages: list[str] = []
+    monkeypatch.setattr(registration_module.logger, "info", lambda message, *args: messages.append(message % args))
+    original_register = runtime.cudaHostRegister
+
+    def register(pointer: int, size: int, flags: int) -> int:
+        ordinal = len(runtime.registered) + 1
+        assert messages[-1] == f"Registering HWR host range {ordinal}/2: {size} bytes"
+        return original_register(pointer, size, flags)
+
+    monkeypatch.setattr(runtime, "cudaHostRegister", register)
+    monkeypatch.setattr(registration_module.torch.cuda, "cudart", lambda: runtime)
+    monkeypatch.setattr(registration_module, "_consume_last_cuda_error", lambda _runtime, _error: None)
+    regions = (_region("first", 0x1000, 4096), _region("second", 0x3000, 4096))
+    if second_result:
+        with pytest.raises(HostRegistrationError, match="error-7"):
+            CudaHostRegistration.create(regions, max_bytes=None)
+        assert runtime.unregistered == [0x1000]
+    else:
+        registration = CudaHostRegistration.create(regions, max_bytes=None)
+        assert registration.close() == ()
+    assert sum(message.startswith("Registering ") for message in messages) == 2
+    assert sum(message.startswith("Registered ") for message in messages) == (1 if second_result else 2)
+
+
 def test_registration_requires_read_only_capability(monkeypatch: pytest.MonkeyPatch) -> None:
     runtime = _FakeRuntime([0], read_only_supported=False)
     monkeypatch.setattr(registration_module.torch.cuda, "cudart", lambda: runtime)

tests/diffusion/offloader/test_distributed_layerwise_backend.py

@@ -96,7 +96,7 @@ class TestDistributedLayerwiseOffloadHook:
         hook.offload_layer()
         assert not hook.is_materialized
 
-    def test_initialize_failure_keeps_next_block_materialized(self, monkeypatch):
+    def test_initialize_failure_keeps_next_block_materialized(self, monkeypatch, patched_offload_runtime):
         current_block = nn.Linear(2, 2)
         next_block = nn.Linear(2, 2)
         expected = {name: tensor.detach().clone() for name, tensor in next_block.state_dict().items()}
@@ -1373,10 +1373,14 @@ class TestMmapWeightLoading:
 
         synchronize.assert_called()
 
-    def test_hwr_registration_failure_falls_back_to_bounded_staging(
+    @pytest.mark.parametrize("registration_mode", ["auto", "disabled"])
+    @pytest.mark.parametrize("limit_gib", [0.0, 1.5])
+    def test_hwr_registration_selection_uses_bounded_staging(
         self,
         monkeypatch,
         patched_offload_runtime,
+        registration_mode,
+        limit_gib,
     ):
         plan, carrier, lease = _fake_hwr_plan("hwr-registration-fallback")
         backend = DistributedLayerwiseOffloadBackend(
@@ -1385,6 +1389,8 @@ class TestMmapWeightLoading:
                 pin_cpu_memory=True,
                 dp_size=1,
                 dlo_use_allgather=False,
+                dlo_host_registration_mode=registration_mode,
+                dlo_host_registration_limit_gib=limit_gib,
             ),
             torch.device("cpu"),
             host_weight_plan=plan,
@@ -1394,12 +1400,14 @@ class TestMmapWeightLoading:
 
         def fail_registration(*args, **kwargs):
             del args, kwargs
+            assert registration_mode == "auto", "disabled mode entered platform registration"
             raise HostRegistrationError("registration unavailable in CPU test")
 
         def allocate_unpinned_staging(hooks, resident_group=None):
             # Registration selection still observes pin_cpu_memory=True. The
             # CPU-only test avoids asking the host for CUDA-pinned allocations.
             for hook in hooks:
+                assert hook.pin_memory, "registration policy disabled staging pinning"
                 hook.pin_memory = False
             return original_staging_allocator(hooks, resident_group)
 
@@ -1412,6 +1420,7 @@ class TestMmapWeightLoading:
         assert backend._using_rank_local_mmap
         assert not backend._using_registered_mmap
         assert backend._host_registration is None
+        assert backend.config.pin_cpu_memory
         assert all(len(hook.cpu_staging_buffers) == 2 for group in backend._all_hook_groups for hook in group)
         assert not lease.closed
 
@@ -2630,7 +2639,9 @@ class TestDistributedComponentSelection:
             assert registry is None or registry.get_hook("distributed_layerwise_offload") is None
             torch.testing.assert_close(block.weight, expected)
 
-    def test_multirank_enable_failure_cleanup_skips_restore_collective(self, monkeypatch, mocker):
+    def test_multirank_enable_failure_cleanup_skips_restore_collective(
+        self, monkeypatch, mocker, patched_offload_runtime
+    ):
         backend = DistributedLayerwiseOffloadBackend(
             OffloadConfig(
                 strategy=OffloadStrategy.DISTRIBUTED_LAYER_WISE,
@@ -2811,7 +2822,7 @@ class TestDistributedComponentSelection:
         with pytest.raises(ValueError, match="not declared replicated"):
             backend.enable(pipeline)
 
-    def test_encoder_allgather_rejects_stub_rank_before_block_discovery(self):
+    def test_encoder_allgather_rejects_stub_rank_before_block_discovery(self, patched_offload_runtime):
         """Every rank must reject an unsafe encoder group, including stub ranks."""
         backend = DistributedLayerwiseOffloadBackend(
             OffloadConfig(

tests/entrypoints/test_async_omni_diffusion_config.py

@@ -503,12 +503,12 @@ def test_serve_cli_forwards_hwr_policy_for_no_allgather_dlo():
             "--omni",
             "--enable-distributed-layerwise-offload",
             "--dlo-no-use-allgather",
-            "--host-weight-runtime-validation",
-            "full_checksum",
             "--host-weight-runtime-mode",
             "preferred",
             "--host-weight-runtime-root",
             "/var/cache/vllm-omni/hwr",
+            "--dlo-host-registration-mode",
+            "disabled",
             "--dlo-host-registration-limit-gib",
             "80",
         ]
@@ -521,11 +521,11 @@ def test_serve_cli_forwards_hwr_policy_for_no_allgather_dlo():
     assert explicit_kwargs["host_weight_runtime_mode"] == "preferred"
     assert explicit_kwargs["host_weight_runtime_root"] == "/var/cache/vllm-omni/hwr"
     assert explicit_kwargs["dlo_host_registration_limit_gib"] == 80
-    assert explicit_kwargs["host_weight_runtime_validation"] == "full_checksum"
-    assert engine_args["host_weight_runtime_validation"] == "full_checksum"
     assert engine_args["host_weight_runtime_mode"] == "preferred"
     assert engine_args["host_weight_runtime_root"] == "/var/cache/vllm-omni/hwr"
     assert engine_args["dlo_host_registration_limit_gib"] == 80
+    assert explicit_kwargs["dlo_host_registration_mode"] == "disabled"
+    assert engine_args["dlo_host_registration_mode"] == "disabled"
 
 
 def test_serve_cli_accepts_diffusion_compile_controls():

vllm_omni/config/omni_config.py

@@ -739,7 +739,7 @@ class _DiffusionConfigProjection:
     dlo_resident_layers: int = Field(default=0, ge=0)
     host_weight_runtime_mode: Literal["disabled", "preferred", "required"] = "disabled"
     host_weight_runtime_root: str | None = None
-    host_weight_runtime_validation: str = "manifest_and_metadata"
+    dlo_host_registration_mode: str = "auto"
     dlo_host_registration_limit_gib: float = Field(default=0.0, ge=0)
     pin_cpu_memory: bool = True
     diffusion_compile_granularity: Literal["regional", "full"] = "regional"
@@ -893,10 +893,10 @@ class _DiffusionConfigProjection:
         validate_host_weight_runtime_options(
             mode=self.host_weight_runtime_mode,
             root=self.host_weight_runtime_root,
-            validation=self.host_weight_runtime_validation,
         )
         self.dlo_host_registration_limit_gib = validate_dlo_host_registration_options(
             limit_gib=self.dlo_host_registration_limit_gib,
+            mode=self.dlo_host_registration_mode,
             enable_dlo=self.enable_distributed_layerwise_offload,
             use_allgather=self.dlo_use_allgather,
             hwr_mode=self.host_weight_runtime_mode,

vllm_omni/config/stage_config.py

@@ -483,7 +483,7 @@ class StageDeployConfig:
     dlo_resident_layers: int | None = None
     host_weight_runtime_mode: str | None = None
     host_weight_runtime_root: str | None = None
-    host_weight_runtime_validation: str | None = None
+    dlo_host_registration_mode: str | None = None
     dlo_host_registration_limit_gib: float | None = None
     # Diffusion-specific debug and observability knobs.
     enable_diffusion_pipeline_profiler: bool | None = None

vllm_omni/diffusion/data.py

@@ -100,9 +100,7 @@ def normalize_omni_diffusion_kwargs(kwargs: Mapping[str, Any]) -> dict[str, Any]
     return normalized
 
 
-def validate_host_weight_runtime_options(
-    *, mode: object, root: object, validation: object = "manifest_and_metadata"
-) -> None:
+def validate_host_weight_runtime_options(*, mode: object, root: object) -> None:
     """Validate HWR policy without touching the configured storage domain.
 
     Filesystem locality and store construction belong to the eligible loader
@@ -111,8 +109,6 @@ def validate_host_weight_runtime_options(
     """
     if mode not in {"disabled", "preferred", "required"}:
         raise ValueError("host_weight_runtime_mode must be disabled, preferred, or required")
-    if validation not in ("manifest_and_metadata", "full_checksum"):
-        raise ValueError("host_weight_runtime_validation must be manifest_and_metadata or full_checksum")
     if mode != "disabled" and (not isinstance(root, str) or not root.strip()):
         raise ValueError("enabled Host Weight Runtime requires host_weight_runtime_root")
 
@@ -123,8 +119,15 @@ def validate_dlo_host_registration_options(
     enable_dlo: bool,
     use_allgather: bool,
     hwr_mode: object,
+    mode: object = "auto",
 ) -> float:
     """Validate the optional transport budget without probing CUDA or HWR."""
+    if mode not in ("auto", "disabled"):
+        raise ValueError("dlo_host_registration_mode must be auto or disabled")
+    if mode == "disabled" and (not enable_dlo or use_allgather or hwr_mode == "disabled"):
+        raise ValueError(
+            "disabled dlo_host_registration_mode requires enabled no-AllGather DLO and Host Weight Runtime"
+        )
     if not isinstance(limit_gib, (int, float, str)):
         raise TypeError(f"dlo_host_registration_limit_gib must be a number; got {type(limit_gib).__name__}")
     value = float(limit_gib)
@@ -835,9 +838,9 @@ class OmniDiffusionConfig:
     # existing loader/storage path.
     host_weight_runtime_mode: str = "disabled"
     host_weight_runtime_root: str | None = None
-    host_weight_runtime_validation: str = "manifest_and_metadata"
     # Optional per-worker ceiling for registering final-layout HWR mappings.
     # Zero adds no ceiling; pin_cpu_memory controls whether registration is tried.
+    dlo_host_registration_mode: str = "auto"
     dlo_host_registration_limit_gib: float = 0.0
 
     pin_cpu_memory: bool = True  # Use pinned memory for faster transfers when offloading
@@ -1246,10 +1249,10 @@ class OmniDiffusionConfig:
         validate_host_weight_runtime_options(
             mode=self.host_weight_runtime_mode,
             root=self.host_weight_runtime_root,
-            validation=self.host_weight_runtime_validation,
         )
         self.dlo_host_registration_limit_gib = validate_dlo_host_registration_options(
             limit_gib=self.dlo_host_registration_limit_gib,
+            mode=self.dlo_host_registration_mode,
             enable_dlo=self.enable_distributed_layerwise_offload,
             use_allgather=self.dlo_use_allgather,
             hwr_mode=self.host_weight_runtime_mode,

vllm_omni/diffusion/model_loader/host_weight_loader.py

@@ -26,7 +26,6 @@ from vllm_omni.diffusion.model_loader.host_weight_plan import HostWeightPlan, Te
 logger = init_logger(__name__)
 
 if TYPE_CHECKING:
-    from vllm_omni.diffusion.data import OmniDiffusionConfig
     from vllm_omni.diffusion.model_loader.host_weights.identity_adapter import FinalLayoutIdentityContext
     from vllm_omni.diffusion.model_loader.host_weights.source_identity import (
         NodeSourceDigestCache,
@@ -41,8 +40,6 @@ class _HWRCommitError(RuntimeError):
 class HWRLoaderMixin:
     """Optional final-layout HWR behavior shared by diffusion loaders."""
 
-    od_config: OmniDiffusionConfig
-
     @staticmethod
     def _identity_value(value: object) -> object:
         """Convert config objects into deterministic identity metadata."""
@@ -322,12 +319,10 @@ class HWRLoaderMixin:
             HostWeightLeaseCarrier,
             HostWeightRuntime,
             HostWeightRuntimeConfig,
-            IntegrityPolicy,
             ProductionPolicy,
             ResolutionOutcome,
             RuntimeMode,
             StorageDomainPolicy,
-            ValidationLevel,
         )
         from vllm_omni.host_weight_runtime.filesystem import detect_storage_class
 
@@ -368,11 +363,6 @@ class HWRLoaderMixin:
             HostWeightRuntimeConfig(
                 mode=mode,
                 domain=StorageDomainPolicy(root=root, storage_class=detect_storage_class(root)),
-                integrity=IntegrityPolicy(
-                    local_lookup=ValidationLevel(
-                        getattr(self.od_config, "host_weight_runtime_validation", "manifest_and_metadata")
-                    ),
-                ),
                 production=ProductionPolicy(
                     allow_local_build=False,
                     allow_post_load_publish=True,

vllm_omni/diffusion/offloader/base.py

@@ -73,12 +73,15 @@ class OffloadConfig:
     # Optional per-worker ceiling for registering an HWR mmap. Zero means no
     # additional ceiling; pin_cpu_memory controls whether registration is tried.
     dlo_host_registration_limit_gib: float = 0.0
+    dlo_host_registration_mode: str = "auto"
     # ``None`` preserves the model's legacy plan-driven component topology;
     # a frozenset is an explicit compact-API selection.
     components: frozenset[str] | None = None
     dlo_transfers: dict[str, DLOTransfer] | None = None
 
     def __post_init__(self) -> None:
+        if self.dlo_host_registration_mode not in ("auto", "disabled"):
+            raise ValueError("dlo_host_registration_mode must be auto or disabled")
         if self.components is not None:
             self.components = parse_offload_components(self.components)
         if self.dlo_transfers is None:
@@ -174,7 +177,9 @@ class OffloadConfig:
         dlo_transfers = dict(resolved.transfers)
         dlo_resident_layers = resolved.resident_layers
         dit_uses_allgather = resolved.uses_allgather(DIT_COMPONENT)
+        registration_mode = getattr(od_config, "dlo_host_registration_mode", "auto")
         dlo_host_registration_limit_gib = validate_dlo_host_registration_options(
+            mode=registration_mode,
             limit_gib=getattr(od_config, "dlo_host_registration_limit_gib", 0.0),
             enable_dlo=enable_distributed_layerwise_offload,
             use_allgather=dit_uses_allgather,
@@ -210,6 +215,7 @@ class OffloadConfig:
             dlo_use_allgather=dit_uses_allgather,
             dlo_resident_layers=dlo_resident_layers,
             dlo_host_registration_limit_gib=dlo_host_registration_limit_gib,
+            dlo_host_registration_mode=registration_mode,
             components=components,
             dlo_transfers=dlo_transfers,
         )

vllm_omni/diffusion/offloader/cuda_host_registration.py

@@ -6,12 +6,14 @@ from __future__ import annotations
 
 import ctypes
 import mmap
+import time
 from collections import defaultdict
 from collections.abc import Sequence
 from dataclasses import dataclass
 from typing import Protocol
 
 import torch
+from vllm.logger import init_logger
 
 from vllm_omni.host_weight_runtime import MappedHostRegion
 
@@ -21,6 +23,8 @@ from .host_registration import (
     HostRegistrationError,
 )
 
+logger = init_logger(__name__)
+
 _CUDA_HOST_REGISTER_READ_ONLY = 0x08
 _CUDA_DEVICE_ATTRIBUTE_HOST_REGISTER_READ_ONLY_SUPPORTED = 113
 
@@ -187,7 +191,9 @@ class CudaHostRegistration:
 
         registered: list[_AddressRange] = []
         try:
-            for region in mapped:
+            for index, region in enumerate(mapped, start=1):
+                logger.info("Registering HWR host range %d/%d: %d bytes", index, len(mapped), region.size)
+                started = time.perf_counter()
                 error = runtime.cudaHostRegister(region.start, region.size, _CUDA_HOST_REGISTER_READ_ONLY)
                 if int(error) != 0:
                     raise HostRegistrationError(
@@ -195,6 +201,9 @@ class CudaHostRegistration:
                         f"[{region.start:#x}, {region.end:#x}): {_handled_error_message(runtime, error)}"
                     )
                 registered.append(region)
+                logger.info(
+                    "Registered HWR host range %d/%d in %.3f s", index, len(mapped), time.perf_counter() - started
+                )
         except Exception as exc:
             rollback_errors: list[str] = []
             rollback_failed: list[_AddressRange] = []

vllm_omni/diffusion/offloader/distributed_layerwise_backend.py

@@ -1080,6 +1080,9 @@ class DistributedLayerwiseOffloadBackend(OffloadBackend):
         lease = self._host_weight_lease
         if lease is None:
             return False
+        if self.config.dlo_host_registration_mode == "disabled":
+            logger.info("HWR mmap registration disabled by transport policy; using bounded host staging")
+            return False
         if not self.config.pin_cpu_memory:
             logger.info("HWR mmap registration disabled by pin_cpu_memory=False; using bounded host staging")
             return False
@@ -1089,6 +1092,12 @@ class DistributedLayerwiseOffloadBackend(OffloadBackend):
 
         limit_gib = self.config.dlo_host_registration_limit_gib
         max_bytes = int(limit_gib * 1024**3) if limit_gib > 0 else None
+        logger.info(
+            "Starting HWR mmap registration on %s: %d source range(s), budget_bytes=%s",
+            self.device,
+            len(lease.mapped_regions),
+            max_bytes,
+        )
         started = time.perf_counter()
         try:
             registration = register_host_mappings(

vllm_omni/engine/arg_utils.py

@@ -582,7 +582,7 @@ class OrchestratorArgs:
     dlo_resident_layers: int = 0
     host_weight_runtime_mode: str = "disabled"
     host_weight_runtime_root: str | None = None
-    host_weight_runtime_validation: str = "manifest_and_metadata"
+    dlo_host_registration_mode: str = "auto"
     dlo_host_registration_limit_gib: float = 0.0
     boundary_ratio: float | None = None
     flow_shift: float | None = None

vllm_omni/engine/async_omni_engine.py

@@ -1145,7 +1145,7 @@ class AsyncOmniEngine:
             "dlo_resident_layers": kwargs.get("dlo_resident_layers", 0),
             "host_weight_runtime_mode": kwargs.get("host_weight_runtime_mode", "disabled"),
             "host_weight_runtime_root": kwargs.get("host_weight_runtime_root"),
-            "host_weight_runtime_validation": kwargs.get("host_weight_runtime_validation", "manifest_and_metadata"),
+            "dlo_host_registration_mode": kwargs.get("dlo_host_registration_mode", "auto"),
             "dlo_host_registration_limit_gib": kwargs.get("dlo_host_registration_limit_gib", 0.0),
             "enforce_eager": False if kwargs.get("enforce_eager") is None else kwargs.get("enforce_eager"),
             "diffusion_compile_granularity": (

vllm_omni/entrypoints/cli/serve.py

@@ -770,15 +770,6 @@ class OmniServeCommand(CLISubcommand):
                 "preferred first."
             ),
         )
-        omni_config_group.add_argument(
-            "--host-weight-runtime-validation",
-            choices=("manifest_and_metadata", "full_checksum"),
-            default="manifest_and_metadata",
-            help=(
-                "HWR warm-acquisition validation. The default checks metadata, not payload corruption; "
-                "full_checksum reads and hashes every payload before restoring weights."
-            ),
-        )
         omni_config_group.add_argument(
             "--host-weight-runtime-root",
             type=str,
@@ -789,6 +780,17 @@ class OmniServeCommand(CLISubcommand):
                 "the same persistent path for population and serving."
             ),
         )
+        omni_config_group.add_argument(
+            "--dlo-host-registration-mode",
+            choices=("auto", "disabled"),
+            default="auto",
+            help=(
+                "HWR transport registration policy for eligible no-AllGather DLO. "
+                "auto attempts registered direct H2D under the existing pin-memory and budget policy; "
+                "disabled selects bounded staging without registering the HWR mappings. "
+                "This preserves the pin-memory policy for staging buffers."
+            ),
+        )
         omni_config_group.add_argument(
             "--dlo-host-registration-limit-gib",
             type=float,