[Bugfix] Preserve Marlin runtime tensor storage across weight reload - #48438
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MarlinLinearKernel.process_weights_after_loading allocates a fresh workspace on the kernel object and rebinds layer.g_idx_sort_indices (act-order) as a plain tensor on every call. Neither is a registered parameter or buffer, so the layerwise reload copy-back cannot preserve their storage: after an RL weight reload, captured CUDA graphs keep launching with the freed device pointers. Reuse existing workspace storage in marlin_make_workspace_new via a new `existing` argument, and register g_idx_sort_indices through replace_parameter(prefer_copy=True) so repeated post-load processing recomputes values into the same storage. Co-authored-by: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: Ryan Clark <ryanclark2k@gmail.com>
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…aths The prepare_* functions for the FP8/NVFP4/MXFP8 Marlin fallbacks and the Marlin MoE paths rebind layer.workspace with a fresh allocation on every call. They rerun during weight reload, so captured CUDA graphs keep launching with the freed workspace pointer, same as the MPLinearKernel sites fixed previously. Pass the existing workspace to marlin_make_workspace_new at all eight sites so reload recomputes into the same storage, and cover the dense prepare paths with a CPU pointer-stability test. Co-authored-by: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: Ryan Clark <ryanclark2k@gmail.com>
Sibling-site validation: live capture/reload/replay A/B for all eight folded-in sitesPer the fold-in requested on the RFC: all eight sibling workspace sites are fixed in this PR, and rather than leaving five of them at static analysis, every site now has live capture/reload/replay evidence on both sides of the fix — bug side on
The original Notes:
MXFP4 MoE checkpoint generation (llm-compressor 0.12.0, compressed-tensors 0.17.1)from transformers import AutoModelForCausalLM, AutoTokenizer
from llmcompressor import oneshot
from llmcompressor.modifiers.quantization import QuantizationModifier
model_id = "nm-testing/tinysmokeqwen3moe"
model = AutoModelForCausalLM.from_pretrained(model_id, torch_dtype="bfloat16")
tok = AutoTokenizer.from_pretrained(model_id)
recipe = QuantizationModifier(
targets="Linear",
scheme="MXFP4",
ignore=["lm_head", "re:.*mlp.gate$"],
)
oneshot(model=model, recipe=recipe)
model.save_pretrained("tinysmoke-mxfp4")
tok.save_pretrained("tinysmoke-mxfp4")vLLM loads it via Supplementary: Full logs for every run are retained and available on request. |
| # On weight reload, reuse compatible storage so the workspace address | ||
| # captured by CUDA graphs stays valid. | ||
| if existing is not None and existing.device == device and existing.numel() == size: | ||
| return existing.zero_() |
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We can just raise error here I think?
if (
existing.device != device
or existing.dtype != torch.int
or existing.numel() != size
):
raise ValueError("Existing Marlin workspace is incompatible")
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Done, it now raises on device/dtype/numel mismatch instead of allocating a new tensor. Agreed this should raise, since silently reallocating would reproduce the original bug one level down. Added a unit test covering the reuse path and both raise paths.
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| replace_parameter( | ||
| layer, "g_idx_sort_indices", g_idx_sort_indices, prefer_copy=True | ||
| ) |
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Keep sort indices out of reload accounting
For act-order Marlin models using layerwise reload, registering g_idx_sort_indices as a Parameter makes it visible to get_layer_params_buffers()/get_layer_size(), but checkpoints never load this generated permutation. info.load_numel_total therefore includes this extra size_k tensor while load_numel can only account for qweight/scales/g_idx, so _layerwise_process cannot run when the layer finishes loading and every such layer is deferred to finalization, buffering all loaded weights and defeating the layerwise memory cap; large act-order GPTQ/AWQ reloads can OOM. Preserve the storage without counting it as a loadable checkpoint parameter, or exclude it from reload sizing.
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I traced this and the total doesn't get inflated. record_metadata_for_reloading runs at model construction (model_loader/utils.py:64), before any weights load and before process_weights_after_loading ever runs, so the restore set contains only the checkpoint-format params. On reload, initialize_layerwise_reload first snapshots the live post-process params into kernel_tensors (that's the set copy-back preserves, and the only place g_idx_sort_indices is meant to appear), then restore_layer_on_meta deletes the current params and re-registers the construction-time set, and only after that is load_numel_total computed (reload/layerwise.py:111-133). The mid-stream refresh at layerwise.py:177 can't pick it up either, since processing hasn't run yet at that point. So the permutation is never part of the loadable total; it only reappears inside _layerwise_process, after the layer has already hit its total. There's an existing precedent for this shape: input_global_scale in the same prepare path is a generated Parameter that checkpoints never load, handled the same way.
To pin the invariant I added test_marlin_act_order_layerwise_reload_accounting: it runs an act-order Marlin layer through record → process → initialize_layerwise_reload → streamed weight loads, and asserts that load_numel_total equals the checkpoint-loadable numel (excluding the permutation) and that the layer processes as soon as its last checkpoint tensor arrives rather than deferring to finalization. I also verified the test discriminates: with the ordering this finding assumes (metadata captured after processing), the total inflates from 1280 to 1408 and the first assert fails.
…allocating An existing workspace that mismatches on device, dtype, or size means the address captured by CUDA graphs is already unusable; silently allocating a replacement would reintroduce the reload staleness one level down. Raise with the expected and actual properties instead, per review. Co-authored-by: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: Ryan Clark <ryanclark2k@gmail.com>
…ting Review flagged that registering g_idx_sort_indices as a Parameter could inflate load_numel_total (checkpoints never load it), deferring act-order layers to finalization and defeating the layerwise memory cap. That does not happen: restore metadata is recorded at model construction, and initialize_layerwise_reload restores that tensor set before sizing, so generated parameters are never part of the loadable total. Pin the invariant with a test that walks an act-order Marlin layer through the layerwise reload flow, asserting the total matches the checkpoint numel and the layer processes during streaming, with copy-back preserving the original sort-indices parameter. Extracts the act-order kernel setup into shared helpers. Co-authored-by: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: Ryan Clark <ryanclark2k@gmail.com>
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CI enabled, let's get it merged today if ci looks good. |
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Hi @RyanClark2k, the pre-commit checks have failed. Please run: uv pip install pre-commit>=4.5.1
pre-commit install
pre-commit run --all-filesThen, commit the changes and push to your branch. For future commits, |
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The reasons for the four failures:
None of these are related to the PR's changes. |
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Sure, I think 48478 is the final plan but it involve to much refactor for now. |
…llm-project#48438) Signed-off-by: Ryan Clark <ryanclark2k@gmail.com> Co-authored-by: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: aoshen02 <aoshen@inferact.ai>
…llm-project#48438) Signed-off-by: Ryan Clark <ryanclark2k@gmail.com> Co-authored-by: Claude Fable 5 <noreply@anthropic.com>
…llm-project#48438) Signed-off-by: Ryan Clark <ryanclark2k@gmail.com> Co-authored-by: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: Tej Kiran <kiran.tej@amd.com>
…llm-project#48438) Signed-off-by: Ryan Clark <ryanclark2k@gmail.com> Co-authored-by: Claude Fable 5 <noreply@anthropic.com> Signed-off-by: root <root@smci355-ccs-aus-m02-09.cs-aus.dcgpu>
The fix is verified at three levels: red/green CPU regression tests (in this PR), live-engine GPU validation on an RTX 4090 (pointer identity across reload, a graph-coupling flip test, and a livelock demonstration on unfixed main), and live bug-side/fixed-side validation of every sibling Marlin path. Method, results, and the validation script for the primary fix are in this description; the per-site sibling matrix is in the validation results comment on this PR.
Part of RFC #48312 ("Weight Reload Correctness for RL") — addresses the "Marlin workspace and sort indices" row of the high-risk candidates table. The workspace pattern is not specific to this kernel: eight more sites across the Marlin family share it. At the RFC author's request (comment), all eight are folded into this PR as one-line applications of the same helper, each live-validated on both sides of the fix. Details under "Scope note for reviewers" below.
Purpose
MarlinLinearKernel.process_weights_after_loadingcreates two runtime tensors that escape the layerwise-reload protection:self.workspace(vllm/model_executor/kernels/linear/mixed_precision/marlin.py) is allocated fresh on every call and stored on the kernel object, not the layer. The reload copy-back (_copy_and_restore_kernel_tensorsinvllm/model_executor/model_loader/reload/layerwise.py) only preserves registered parameters/buffers (layer._parameters/layer._buffers), so after an RL weight reload the old workspace is freed while captured CUDA graphs keep launching Marlin kernels against its stale device pointer. Affects all Marlin models (GPTQ, AWQ, compressed-tensors W4A16/W4A8) when CUDA graphs are enabled (the default).layer.g_idx_sort_indices(act-order GPTQ only) is a plainargsortoutput assigned as a bare attribute — never registered — with the same lifecycle gap. Since it is a permutation the kernel reads, stale/reused memory means wrong outputs rather than scratch corruption.Verified benign, no change needed: the non-act-order empty
g_idx/w_zp/g_idx_sort_indicespaths (marlin_make_empty_g_idxreturns a zero-numelnn.Parameter, whichnn.Module.__setattr__auto-registers) andinput_global_scale(registered, covered by copy-back).Fix
Follows the invariant stated in RFC #48312 (recompute values into the same storage on reload) and the pattern of #48251:
marlin_make_workspace_newgains anexistingargument: when a compatible workspace is passed, it is zeroed and returned in place instead of reallocated.MarlinLinearKernelpasses its current workspace on reprocessing.g_idx_sort_indicesis registered viareplace_parameter(..., prefer_copy=True), so repeated post-load processing copies new indices into the same storage, and the layerwise copy-back protects it going forward.This does not change serving-path numerics — the tensors hold identical values; only their storage identity across reloads changes — so no model eval delta is expected. The GPU validation below covers the behavioral claim on the reload path.
Scope note for reviewers
The same unregistered
layer.workspace = marlin_make_workspace_new(...)pattern exists at eight more sites, all in functions rerun fromprocess_weights_after_loadingduring reload: the dense FP8/NVFP4/MXFP8 Marlin fallbacks (marlin_utils_fp8.py:135/466,marlin_utils_fp4.py:243), the FP8/MXFP8/NVFP4/MXFP4 Marlin MoE paths (marlin_utils_fp8.py:283/552,marlin_utils_fp4.py:399/484), and a conditional rebind in the compressed-tensors WNA16 modular MoE path (compressed_tensors_moe_wna16_marlin.py:490). At the RFC author's request, all eight are fixed in this PR (second commit) by passing the existing workspace to the helper. Every site is live-validated with the same capture/reload/replay pointer census that validates the primary fix — bug side and fixed side — see the validation results comment on this PR for the full per-site matrix.Deliberately untouched:
auto_awq.py/auto_gptq.pyassign their workspace increate_weights, which does not rerun on reload, and the WNA16 MoE converter'sw13/w2_g_idx_sort_indicesgo through_replace_or_register_parameterand are already protected.Test Plan
CPU lifecycle regression tests (in this PR, no GPU required), both in
tests/model_executor/model_loader/test_reload.py:test_marlin_post_load_preserves_runtime_tensor_addresses: builds a realMarlinLinearKernelover a minimal act-order GPTQ layer (only the two CUDA-only pieces are monkeypatched:num_compute_unitsandops.gptq_marlin_repack), runs post-load processing, simulates a reload by installing fresh checkpoint-format weights with a different act-order, processes again, and asserts bothdata_ptrs are stable, the sort indices refresh to the new permutation, and the workspace is zeroed.test_marlin_prepare_layer_preserves_workspace_address[fp8|mxfp8|nvfp4]: runs the actualprepare_fp8_layer_for_marlin,prepare_mxfp8_layer_for_marlin, andprepare_fp4_layer_for_marlinfallback paths twice on a minimal layer (same two monkeypatches) and asserts the workspacedata_ptris stable and zeroed.GPU validation: capture -> reload -> replay. Setup: RTX 4090 (SM89), torch 2.11.0+cu130,
VLLM_USE_PRECOMPILED=1editable install, modelTheBloke/TinyLlama-1.1B-Chat-v1.0-GPTQrevisiongptq-4bit-32g-actorder_True(desc_act=true, so all 88 linear modules take the act-order Marlin path), CUDA graphs at defaults (FULL_AND_PIECEWISE), prefix caching off, greedy decoding. Log confirmsUsing MarlinLinearKernel for AutoGPTQLinearMethod.The validation script generates, records
data_ptrof every Marlin workspace andg_idx_sort_indicesinside the live engine viallm.apply_model, reloads identical weights throughWorker.reload_weights, records the pointers again, then flips the live sort-indices permutations in place and generates again. The flip distinguishes whether captured graphs read the storage the engine mutates (correct) or stale memory (bug), independent of allocator behavior.To reproduce on each side of the A/B (any SM75+ GPU, roughly five minutes with warm caches):
validate_marlin_reload.py
Test Result
CPU:
kernel.workspace.data_ptr()(workspace reallocated on reload); theg_idx_sort_indices.data_ptr()assertion was additionally verified red in isolation (address changed across reload). All threetest_marlin_prepare_layer_preserves_workspace_addressvariants likewise fail with the sibling-site fixes reverted and pass with them.tests/model_executor/model_loader/test_reload.pysuite pass (macOS CPU,VLLM_TARGET_DEVICE=emptyeditable install; the suite's five engine-spawning e2e tests fail identically on the clean base on this machine — no compiled CPU extension — and are unrelated).ruff checkandruff format --checkclean on all changed files.GPU, unfixed base (
4c81772):Every runtime tensor moved while the captured graphs kept the old addresses. The post-reload generation then hung the GPU: temporary allocations from the flip reclaimed the freed workspace blocks, so the replayed Marlin kernels spun on garbage synchronization counters. In an RL loop this wedges the rollout engine, not just corrupts outputs.
One honest note: a naive version of this test (reload identical weights, compare generations, no pointer instrumentation) passes on the unfixed base, because the stale memory still contains bit-identical values until something reclaims it. The bug is real but latent until allocation pressure or changed weights expose it, which is presumably why it survived in tree.
GPU, fixed (this PR's branch head,
34ad158):Storage identity holds across reload, and the flip test confirms the graphs read the same storage the engine mutates. (First validated on the initial commit
1e6bdf3; re-run with identical results on the branch head after folding in the sibling fixes.)GPU, sibling sites: all eight folded-in sites are live-validated bug-side/fixed-side with the same pointer-census method — full per-site matrix, models, and reproduction details in the validation results comment on this PR. Full logs for all runs are retained and available on request.
GPU, test suite: all
test_reload.pyunit tests (including this PR's) and all of its engine-spawning e2e cases pass on the 4090.Duplicate-work check
No open PR references #48312. Searches for "marlin workspace", "marlin reload", and "g_idx_sort_indices" surface only unrelated kernel-bounds fixes. The RFC thread has no claims on this item. The RFC author's open PRs in this campaign (#48251, #48382) cover MLA/FlashInfer sinks and compressed-tensors WNA16 Triton MoE respectively — not the Marlin path.
AI assistance disclosure
Investigation and implementation were AI-assisted (Claude Code). I have reviewed every changed line, re-derived the root-cause analysis against the reload machinery myself, and run the tests locally.