[https://nvbugs/6607487][fix] fix LoRA host/device cache dtype reconfiguration race - #17678
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…iguration race PeftCacheManager::configureDataType reconfigured the host and device LoraCache dtypes with two independent calls to LoraCache::setDataType. Each call is individually locked, but there is no lock spanning both, so a concurrent LoraCache::copyTask could observe the host cache already switched to the new dtype while the device cache still held the old one (or vice versa), tripping the 'LoRA host and device cache dtypes must match' check. copyTask's dtype check also only locked the device cache's mCacheMutex before reading both mPageManagerConfig.getDataType() values, despite a comment claiming this made the check atomic with respect to cache reconfiguration -- the host side of the comparison was read without holding host's mCacheMutex, racing against a concurrent configureDataType call. Add LoraCache::setDataTypeCoordinated, which reconfigures a pair of caches (host + device) under one combined lock so neither observer nor writer can see a torn state, and use it from configureDataType. Extend copyTask's dtype-check lock to cover both caches' mCacheMutex so the check is actually atomic against setDataTypeCoordinated. Also fix an unrelated mismatched-mutex bug in copyTask where device-cache TaskValue state was guarded by the host cache's mCacheMutex instead of the device cache's. This likely explains the intermittent (~0.5%) hang in test_qwen3_fp8_lora: an exception thrown from the dtype-mismatch check inside PeftCacheManager's ensure-worker-pool thread was not translated into a terminal response for the affected request, so the client blocked in queue.get() until the test's timeout. Re-enable test_qwen3_fp8_lora by removing its waives.txt entry. Signed-off-by: Aurelien Chartier <2567591+achartier@users.noreply.github.com>
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WalkthroughThe change coordinates host and device LoRA cache data-type updates, strengthens locking during cache copies, corrects completion-state locking, and removes the Qwen3 FP8 LoRA test waiver. ChangesLoRA cache coordination
Estimated code review effort: 3 (Moderate) | ~20 minutes Merge Risk: ⚪ Minimal · up to The change coordinates LoRA cache dtype updates and removes the related test waiver; no actionable merge-blocking risk remains beyond normal checks and review. Suggested reviewers: Sequence Diagram(s)sequenceDiagram
participant PeftCacheManager
participant HostLoraCache
participant DeviceLoraCache
PeftCacheManager->>HostLoraCache: setDataTypeCoordinated(DeviceLoraCache, dataType)
HostLoraCache->>DeviceLoraCache: Acquire both cache locks
HostLoraCache->>HostLoraCache: Apply locked data-type update
HostLoraCache->>DeviceLoraCache: Apply locked data-type update
🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
✨ Finishing Touches🧪 Generate unit tests (beta)
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Inline comments:
In `@cpp/tensorrt_llm/runtime/loraCache.cpp`:
- Around line 520-525: Update LoraCache::setDataTypeCoordinated to handle other
== *this before constructing the combined std::scoped_lock, routing the
self-alias case through setDataType or rejecting it; retain the existing
coordinated locking and updates for distinct cache instances.
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📒 Files selected for processing (4)
cpp/include/tensorrt_llm/runtime/loraCache.hcpp/tensorrt_llm/batch_manager/peftCacheManager.cppcpp/tensorrt_llm/runtime/loraCache.cpptests/integration/test_lists/waives.txt
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- tests/integration/test_lists/waives.txt
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…lf-aliasing Passing the same LoraCache as both the receiver and other would lock mPagesMutex/mCacheMutex twice via the same std::scoped_lock call, which is undefined behavior (self-deadlock) for a non-recursive std::mutex. Route that case through the existing single-cache setDataType instead. Addresses CodeRabbit review feedback on PR NVIDIA#17678. Signed-off-by: Aurelien Chartier <2567591+achartier@users.noreply.github.com>
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5 participants
Dev Engineer Review
copyTaskdtype validation and destination task state with the correct cache mutexes.test_qwen3_fp8_loraby removing its waiver.QA Engineer Review
tests/integration/test_lists/waives.txt.unittest/_torch/modules/tests_lora_modules/test_qwen3_sanity.py::TestQwen3LoRA::test_qwen3_fp8_lora.test-db/orqa/files were modified.Description
test_qwen3_fp8_lorahangs intermittently (~0.5% of runs) onmain, timing out after 2400s waiting onqueue.get()intensorrt_llm/executor/result.pybecause the executor never sends a terminal response for the request.Root cause:
PeftCacheManager::configureDataTypereconfigures the host and deviceLoraCachedtypes with two independent, separately-locked calls toLoraCache::setDataType. There is no lock spanning both calls, so a concurrentLoraCache::copyTask(running on the PEFT ensure-worker-pool thread, e.g. for an already-admitted task from an earlier bf16 LoRA test sharing a pooled session) can observe the host cache already switched to the new dtype while the device cache still holds the old one (or vice versa), tripping the"LoRA host and device cache dtypes must match"check and throwing.Compounding this,
copyTask's dtype-consistency check only locked the device cache'smCacheMutexbefore comparing both caches'mPageManagerConfig.getDataType()— despite an existing comment claiming this made the check atomic with respect to cache reconfiguration. The host side of the comparison was read without holding the host cache'smCacheMutex, so it raced against a concurrentconfigureDataTypecall touching the host cache.An exception thrown from inside the ensure-worker-pool's async task propagates through
std::future::get()uncaught, which is consistent with the observed symptom: the request never receives a terminal response and the client hangs until timeout.Fix
LoraCache::setDataTypeCoordinated(LoraCache& other, dataType), which reconfigures a host+device cache pair under one combined lock (mPagesMutex+mCacheMutexon both caches) so neither a reader nor the two writes can observe a torn state.PeftCacheManager::configureDataTypenow calls this instead of two separatesetDataTypecalls.copyTask's dtype-check lock to cover both caches'mCacheMutex(previously only the device cache's), making the check actually atomic with respect tosetDataTypeCoordinated.copyTask: device-cacheTaskValuestate (otherTaskValue->loaded/loadInProgress) was being guarded by the host cache'smCacheMutexinstead of the device cache's.waives.txtSKIP fortest_qwen3_fp8_lora(nvbugs/6607487) now that the race is fixed.Test Coverage
cpp/tests/unit_tests/runtime/loraCacheTest— 10/10 pass (coverscopyToPages,basicPutGet, etc., the code paths touched by this fix)cpp/tests/unit_tests/batch_manager/peftCacheManagerTest—PeftCacheManagerTest.*10/10 pass, includinggptManagerSim(500-request randomized-batch simulation exercisingaddRequestPeft/ensureBatch/copyTaskrepeatedly)tests/unittest/_torch/modules/tests_lora_modules/(the CI wrapper scope for this flake, includes both bf16 and FP8 LoRA tests sharing a pooled session) — looped 25x on a B200, 9 passed / 4 skipped (missing larger MoE model) each time, no hangs or regressionsPR Checklist
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