[Bugfix] cumem: validate VA/handle invariants and recover from wake-time cuMemMap failures by terafin · Pull Request #45565 · vllm-project/vllm

terafin · 2026-06-14T05:56:42Z

Summary

On hot wake_up from cumem sleep mode (default backend), cuMemMap at csrc/cumem_allocator.cpp:169 can return CUDA_ERROR_INVALID_VALUE ("invalid argument") when d_mem already has a live mapping carried over from a prior cycle whose cuMemUnmap silently failed.

The failure is silent because the global error_code is sticky — a previous failed call leaves error_code != 0, the next create_and_map short-circuits its if (error_code != 0) return; guard before cuMemMap is ever attempted, and wake_up's Python loop then aborts mid-iteration. On TP/PP multi-proc executors the affected worker wedges in shared-memory broadcast while the APIServer keeps returning /health=200.

This PR adds three thin, independently-useful defenses, each covered by its own unit test.

Changes

1. `csrc/cumem_allocator.cpp` — invariant reset + cuMemMap recovery

create_and_map clears the global error_code at function entry so a sticky error from a prior cycle cannot short-circuit a fresh attempt.
On cuMemMap returning CUDA_ERROR_INVALID_VALUE, performs one idempotent cuMemUnmap + cuMemMap retry. The cuMemUnmap is harmless if nothing was mapped (returns its own INVALID_VALUE, which we ignore); it clears a stale mapping if one exists, letting the retry succeed.
On persistent failure the freshly-created handle is released so we do not leak a CUmemGenericAllocationHandle on the recovery path.

2. `vllm/device_allocator/cumem.py` — structured wake_up failure

CuMemAllocator.wake_up now wraps each per-allocation create_and_map call in try/except.
Iteration continues through every entry even after a failure, so post-wake state is deterministic — every allocation has either been remapped or recorded as failed.
At end of loop, if any allocations failed, raises a new WakeUpPartialFailure(failed_pointers, first_exception) exception (a RuntimeError subclass for backward compatibility) carrying the structured list of failed device pointers and the first underlying CUDA error.
Existing except RuntimeError: callers still catch it; new callers can isinstance(e, WakeUpPartialFailure) for structured handling and decide between per-allocation retry and worker-wide cold restart instead of returning 200 while a worker is silently wedged.

3. `tests/device_allocator/test_cumem_wake_up_recovery.py` — 4 GPU-free unit tests

test_wake_up_propagates_per_allocation_failure_without_corrupting_state — failure on entry 2 of 3 does NOT abort the loop; entry 3 is still attempted; pointer_to_data stays intact for retry.
test_wake_up_raises_structured_exception_on_persistent_failure — structured WakeUpPartialFailure is raised (subclass of RuntimeError, carries failed_pointers + first_exception).
test_wake_up_collects_all_failed_pointers — exception records ALL failed pointers in iteration order, not just the first.
test_wake_up_success_path_unchanged — non-regression sanity check.

The tests stub the C extension and CUDA wrapper via sys.modules so they run on contributor laptops and CI without CUDA, while still exercising the real CuMemAllocator.wake_up loop end-to-end.

Verification

Tests FAIL pre-fix (3 of 4 fail on AttributeError: module 'vllm.device_allocator.cumem' has no attribute 'WakeUpPartialFailure' against the existing wake_up loop; the success-path test still passes as expected since it is a non-regression check). Tests PASS post-fix (4 of 4).

$ pytest tests/device_allocator/test_cumem_wake_up_recovery.py -v
tests/device_allocator/test_cumem_wake_up_recovery.py::test_wake_up_propagates_per_allocation_failure_without_corrupting_state PASSED
tests/device_allocator/test_cumem_wake_up_recovery.py::test_wake_up_raises_structured_exception_on_persistent_failure PASSED
tests/device_allocator/test_cumem_wake_up_recovery.py::test_wake_up_collects_all_failed_pointers PASSED
tests/device_allocator/test_cumem_wake_up_recovery.py::test_wake_up_success_path_unchanged PASSED
========================= 4 passed in 2.97s =========================

Why not the other cumem-related PRs in flight

This PR closes a coverage gap left by the existing in-flight cumem-related work:

[Bugfix] cumem: stream-sync before unmap and at wake_up exit to prevent CUDART illegal-memory crash #45552 (sync-at-wake-exit) — protects cuMemUnmap and cudaMemcpy from in-flight-kernel races. Does NOT pre-validate cuMemMap inputs at wake_up time.
[Bugfix] cumem: quiesce torch.distributed groups around VMM mutations (#45519) #45554 (cross-rank gloo barrier) — protects NCCL communicator state across VMM mutations. Does NOT prevent intra-process VA / handle invariants from being violated.
Patch for vLLM + FlashAttention4 + torch for GRPO colocated training #36535 (error_code reset in my_free + size-mismatch fix) — sister fix on the alloc path; partially addresses wake-side hygiene but does not pre-validate cuMemMap.

These PRs are complementary, not conflicting — this PR can land alongside any subset of them.

References

cumem allocator: double-free and stale error codes during sleep/wake cycles #36651 — 5-bug cumem audit (this fix addresses the wake-side gap)
[Bug]: POST /wake_up causes vLLM process to crash. 500 Internal Server Error #36753 — POST /wake_up → 500 EngineDeadError on H100 single-GPU swap-group; same symptom shape as ours
[Bug]: Error on sleep mode when upgrade into vllm 0.16.0 #35463 — cuMemAddressReserve "invalid argument" on v0.16.0 (different line, same allocator family)

Empirical context

Observed on a 4×RTX 3090 production cluster running Qwen3.6-27B AWQ-BF16-INT4 with TP=2 PP=2 under continuous sleep/wake cycling (sub-3-second sleep-after-wake intervals). Wake_up returns HTTP 200, then engine-core wedges in shm_broadcast forever, /health lies (returns 200), and only docker rm -f + recreate recovers. The crash signature in our logs matches csrc/cumem_allocator.cpp:169 exactly.

AI disclosure

Investigation, drafting, and test authorship done under human supervision with Claude (Opus 4.7). Trailers preserved per project conventions.

🤖 Generated with Claude Code

github-actions · 2026-06-14T05:56:51Z

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Sync-upstream has been failing closed since 2026-06-14T06:18Z because the auto-carry phase cherry-picked terafin's PR vllm-project#45565 (cumem wake_up recovery) which includes csrc/cumem_allocator.cpp. The post-cherry-pick CARRY-DRIFT guard correctly rejects compiled-code carries on precompiled-wheel forks (the wheel's .so files cannot be relinked at runtime), but doing so blocks ALL other Python-only carries from landing. Add an early per-PR skip inside the cherry-pick loop, gated on PRECOMPILED_WHEEL_BASE_URL. PRs touching csrc/ kernels/ or compiled-code extensions emit a ::warning:: and are skipped; Python-only PRs continue to carry as before. The CARRY-DRIFT guard remains as the safety net. Side-effect: PR vllm-project#45565 cannot land on :latest via the carry mechanism and must wait for upstream merge. Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

…mpiled-wheel forks The open-PR cherry-pick loop on main had NO precompiled-wheel guard: it cherry-picked every terafin-authored open PR onto intarweb-dev unconditionally. PR vllm-project#45565 (csrc/cumem_allocator.cpp) was carried, which then tripped the post-cherry-pick carry-drift guard and FAIL-CLOSED the whole sync — blocking all the Python-only carries (incl. the wake-quiesce fix vllm-project#45554) from reaching intarweb-dev / :latest. The skip block existed only on intarweb-dev (committed directly), but 'git checkout -B intarweb-dev main' wipes it every run, so the workflow that actually executes (on main, the default branch) never had it. Honest-fact vllm-project#97 silent-wipe pattern. Add the early skip into the main loop, BEFORE cherry-pick, using the exact extension set + path prefixes as the carry-drift guard so the two can never disagree. Each skip logs a loud ::warning::. General rule (any compiled-code PR auto-skips); PRECOMPILED_WHEEL_SKIP_PRS var is a belt-and-suspenders explicit fallback. Verified: skips vllm-project#45565, carries vllm-project#45554/vllm-project#45552/vllm-project#45517/vllm-project#45508/vllm-project#45513/vllm-project#45484/vllm-project#45485. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…l template) Heal A re-synced sync-upstream.yml from the canonical template and wiped the skip-on-csrc guard that commit fdfec4f had added directly to main, so sync fell back to fail-closed on vllm-project#45565's csrc/cumem_allocator.cpp. The guard is now in the canonical template (terafin/claude 1.38.42), so future Heal A re-syncs preserve it; this restores it on main NOW so the immediate next sync is green without waiting for the next auto-heal cycle. Byte-identical to the substituted canonical template (only the 39-line guard differs from prior main). Gated on PRECOMPILED_WHEEL_BASE_URL. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

The open-PR cherry-pick loop was missing the early-skip block that drops PRs touching compiled code (csrc/, kernels/, *.cu/*.cpp/etc) BEFORE cherry-pick on precompiled-wheel forks. Without it, PR vllm-project#45565 (C++ cumem recovery) gets cherry-picked into intarweb-dev and trips the post-pick carry-drift guard, which fail-closes the WHOLE sync — blocking every Python-only carry (incl. vllm-project#45554 wake-quiesce, vllm-project#45398 field-restore). This file is now byte-identical to the canonical template (terafin/claude .../templates/sync-upstream.yml @ 72521922b 1.38.42), so the ops-overlay save/restore self-perpetuates it AND portfolio-auto-heal Heal-A computes CUR==CANON and never re-wipes it. Gated on vars.PRECOMPILED_WHEEL_BASE_URL → no-op on the 21 source-build forks. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…ire build dispatch Two fork-CI fixes found by forensics: 1. CARRY-DRIFT auto-skip now fails closed on a flaky per-PR file query. The early precompiled-wheel skip used `gh api .../files 2>/dev/null || true`, which treated an API error/empty as "no compiled files". A C++ PR (vllm-project#45565) slipped past the early skip, got cherry-picked, then tripped the hard carry-drift guard and FAIL-CLOSED the ENTIRE sync 3x (mitigated manually via PRECOMPILED_WHEEL_SKIP_PRS=45565). Now: capture gh exit status, retry once after 5s, and on persistent failure skip THAT PR only (fail-closed per-PR), never silently treating a flaky read as safe-to-carry. 2. Drop the explicit `gh workflow run "Build from source -> GHCR"` dispatch. The intarweb-dev force-push is authored by the org GitHub App token (not GITHUB_TOKEN), so it already triggers build-from-source.yml on push. The extra dispatch double-fired every sync (one push run + one workflow_dispatch run within the same second), wasting CUDA builder capacity. The push trigger is now the single source of truth. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

…e handshake (vllm-project#45519) With --sleep-mode-backend=cumem_tag on a TP>1/PP>1 deployment, wake_up is dispatched to each worker independently and each worker re-maps its own VMM-backed regions at its own pace. The very next decode step issues a cross-rank torch.distributed.broadcast on pp.device_group (_pp_receive_prev_sampled_token_ids_to_input_batch). If a faster rank reaches that collective before a slower rank has finished re-mapping the regions backing the broadcast buffers, the collective issues against memory the peer MMU still treats as invalid -> CUDA_ERROR_ILLEGAL_ADDRESS, after which the NCCL comm is permanently corrupt: the engine deadlocks while /health keeps returning 200. Fix: gate Worker.wake_up on a cross-rank wake-success handshake after the local allocator wake and before returning to the caller, so no rank can reach a device-group collective until every rank has finished its local wake. The handshake is an all-reduce (ReduceOp.MIN) of a per-rank success flag, NOT a bare barrier: a bare barrier after the local wake would strand peers forever if one rank's allocator.wake_up() raised before reaching it, re-introducing the very full-fleet hang we are fixing. The all-reduce instead lets every rank learn that a peer failed and raise symmetrically -- loud, no hang, no rank silently proceeding into a device-group collective against a peer whose wake never completed. The handshake runs on get_world_group().cpu_group (gloo) deliberately so the synchronization itself never touches the not-yet-resynced NCCL device_group. A local torch.cuda.synchronize() is also added at the end of CuMemAllocator.wake_up so a rank drains its own re-map work before reporting success into the cross-rank all-reduce (a purely local guarantee; the cross-rank ordering lives entirely in Worker.wake_up). This is the correct, fully-Python fix. It supersedes the C++ allocator retry approach in vllm-project#45565, which addresses a different symptom and (being compiled-code) cannot be carried as a Python-only patch. Tests (GPU-free, fail-pre/pass-post): tests/v1/worker/test_gpu_worker_wake_barrier.py -- handshake fires on multi-rank cumem configs; ordered after local wake, before return; skipped on single-rank / cumem-disabled; routed through cpu_group (gloo) only; plus the adversarial regressions: a failed local wake still participates in the handshake (no peer hang) and a failed peer makes a healthy rank raise symmetrically. tests/device_allocator/test_cumem_wake_synchronize.py -- wake_up calls torch.cuda.synchronize after the remap/restore work. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com> Signed-off-by: terafin <terafin@users.noreply.github.com>

…lm-project#45610 HOIST f24612b] Single FULL-UNION fork-carry composing ALL wake-path changes onto one base (upstream/main), so the sync open-PR loop never has to apply mutually-adjacent wake-path hunks sequentially (honest-fact vllm-project#54 adjacency clobber). The wake-path PRs touch the SAME hunks; sequential -X-theirs drops them. This commit is the SOLE provider; the PRs (vllm-project#45610 vllm-project#45617 vllm-project#44778 vllm-project#45611 vllm-project#45565) are SKIPPED from the loop via PRECOMPILED_WHEEL_SKIP_PRS. *** vllm-project#45610 DECODE-WEDGE FIX RE-FOLDED: now carries the PP-consensus HOIST (PR vllm-project#45610 head f24612b), REPLACING the earlier pre-hoist gate variant (4d20740). The cudagraph-mode consensus all-reduce is hoisted out of the model runner's execute_model and into Worker.execute_model, issued BEFORE the inter-stage irecv_tensor_dict (gpu_worker.py). This eliminates the structural deadlock cycle that wedged TP2/PP2 at decode step 0 (PP0 ranks parked in coordinate_cudagraph_mode_ across_pp -> all_reduce while PP1 ranks parked in irecv gloo waitRecv). The model runner no longer self-issues the consensus all_reduce; it consumes the agreed value via the new pp_synced_cudagraph_mode kwarg. Applies to V1 (gpu_model_runner.py), V2 (gpu/model_runner.py), DP (gpu/dp_utils.py), and Ray (executor/ray_utils.py) paths, plus pp_utils.py helper. gpu_model_runner.py wake-path markers (HOTPATH_FILE_RESTORE / CARRY_HOTPATH_ASSERTS): vllm-project#44778 _iter_kv_cache_tensors nested-container KV zeroing on wake vllm-project#45617 scale_specs calibrated FP8-KV scale restore on wake gpu_worker.py composition (carried forward from prior union; disjoint region from the hoist's execute_model edits, no adjacency conflict): vllm-project#45398 pluggable sleep-mode backend abstraction (_get_sleep_mode_backend, sleep->backend.suspend, wake_up->backend.resume; adds vllm/device_allocator/sleep_mode_backend.py + executor/abstract.py + config/model.py fields) vllm-project#45619 gate level-2 sleep buffer restore on the weights wake tag vllm-project#45620 do not crash sleep() on shared-GPU device-global free drop vllm-project#45612 cumem_tag PP-broadcast wake race: symmetric gloo wake handshake AUDIT-D composition assertions (verified, not just grepped): - wake_up dispatches backend.resume EXACTLY ONCE (needs_wake_sync if/else are mutually-exclusive branches); NO raw allocator.wake_up Block B double-wake. - the hoist consensus block precedes irecv_tensor_dict in Worker.execute_model. - runner does NOT self-issue the consensus all_reduce (hoist-correct). Tests: test_sleep_mode_backend, test_pp_cudagraph_consensus (V1 hoist), test_pp_cudagraph_consensus_v2 (V2 hoist), test_fp8_kv_scale_wake, test_gpu_model_runner_fp8_wake_up, test_gpu_worker_wake_barrier. cumem.py deliberately excluded (carried by separate FORK_CARRIED entries vllm-project#45615/vllm-project#45552); the load-bearing gloo wake handshake lives in gpu_worker.py. Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>