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feat(nvsnap): import gpushare, checkpoint support for GPU memory shared between processes - #2300
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…tion stack criu-v2 (in-namespace dump and restore with the bundled CRIU) has been the only CRIU engine for every "criu" request; the fork now restores io_uring and epoll state itself. Remove what only the retired engine used: - agent: the go-criu RPC dump and restore branches, the Plan A external mount mapping, the LD_PRELOAD quiesce and uvloop metadata helpers, the D2H multi-GPU interposition branch, the capture streamer, the restore-trigger and GPU-restore HTTP endpoints, and the NVSNAP_CRIU_V2 switch. replay_mounts.go keeps the mount classification criu-v2 uses. - restore-entrypoint binary and the nvsnap-gpu-restore tool. - webhook: the nvsnap.io/auto-inject branch and the in-pod CRIU L2 restore injection. A CRIU capture with a bound rox PVC now falls through to the agent-driven placeholder restore instead of mounting a PVC nothing reads. - server: the GPURestore flow creates a criu-v2 placeholder and POSTs /v1/restore instead of triggering an in-pod restore. - build: lib/nvsnap_intercept, lib/sitecustomize, lib/nvsnap_restore_helper, the libuv, uvloop, libzmq and pyzmq builder images, nvsnap-init, the placeholder images, and their versions.sh, ci/build-image.sh, build-agent.sh, Helm and manifest plumbing. go-criu leaves go.mod and NOTICE. - docs: THIRD-PARTY-FORKS.md now describes the one remaining fork (CRIU). Tests: go test ./..., golangci-lint (no new findings), helm lint and a render of the chart; webhook tests replace the CRIU L2 inject cases with TestL2_CRIUCapture_NotInjected. Co-Authored-By: Balaji Ganesan <bganesan@nvidia.com> Signed-off-by: Balaji Ganesan <bganesan@nvidia.com>
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📝 WalkthroughWalkthroughThis change adds a CUDA interposer and a process-level tool to release and restore shared GPU resources around checkpointing. It also adds build integration, CUDA tests, and Kubernetes workflows for vLLM and CRIU validation. ChangesGPU-share checkpointing
Priority: ➖ Normal Estimated code review effort: 5 (Critical) | ~120 minutes Change: Feature Sequence Diagram(s)sequenceDiagram
participant SuspendTool as nvsnap-gpu-suspend
participant Interposer as gpushare interposer
participant Driver as CUDA Checkpoint API
participant Store as Chunk store
SuspendTool->>Interposer: Quiesce shared GPU work
Interposer->>Driver: Synchronize GPU work
SuspendTool->>Interposer: Release mappings and save allocations
Interposer->>Store: Write allocation chunks
SuspendTool->>Driver: Checkpoint process state
SuspendTool->>Driver: Restore process state
SuspendTool->>Interposer: Load, remap, and resume GPU resources
Interposer->>Store: Read allocation chunks
Merge Risk: 🟡 Moderate · up to The new GPU-sharing shim exposes an unauthenticated local control channel. Through that channel, other processes on the same network can read GPU memory or stall the workload. Multi-GPU processes may also lose peer access to allocations. The validation scripts can destroy a live workload when a step fails. Resolve these issues before merging. 🚥 Pre-merge checks | ✅ 4 | ❌ 1❌ Failed checks (1 warning)
✅ Passed checks (4 passed)
Full details: Docstring CoverageExplanation Docstring coverage is 34.83% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 201 functions across 14 files. (7 skipped: 7 unsupported.) ✨ Finishing Touches 💡 1📝 Generate docstrings 💡
🧪 Generate unit tests (beta)
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Actionable comments posted: 11
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Inline comments:
Review comments at
@src/compute-plane-services/nvsnap/docker/agent/gpushare/gpushare.c:
- Around line 1523-1524: Update the temp-file creation in chunk_write at
src/compute-plane-services/nvsnap/docker/agent/gpushare/gpushare.c, lines
1523-1524, and in prefetch_thread at
src/compute-plane-services/nvsnap/docker/agent/gpushare/nvsnap-gpu-suspend.c,
lines 975-977, to use unique names with a random suffix and open files with
O_CREAT | O_EXCL. Retry with a new name when opening fails with EEXIST.
- Around line 1096-1106: Add SO_PEERCRED validation to ctl_main after accept,
serving connections only when the peer UID is root or matches geteuid(). In
request(), validate the connected server’s credentials before msg_send, checking
the expected UID and expected PID where the PID namespace permits; reject
mismatches.
- Around line 1401-1423: Update w_alloc and valloc_restore to configure VMM
access for peer-capable devices; do not rely on cuCtxEnablePeerAccess alone for
VMM mappings. In valloc_drop and valloc_restore, push the primary context for
the allocation’s v->dev before memory operations and restore the previous
context afterward, including on failure paths.
Review comments at
@src/compute-plane-services/nvsnap/docker/agent/gpushare/nvsnap-gpu-suspend.c:
- Line 561: Update the timeout selection in the command-handling code so both
bare `load` and `load <cache_dir>` commands receive the 3600-second timeout.
Preserve the existing timeout behavior for `release` and other commands.
Review comments at @src/compute-plane-services/nvsnap/docs/GPUSHARE.md:
- Around line 105-109: Update the Validation intro in GPUSHARE.md to identify
Qwen2.5-72B-Instruct only for the results it describes, and state Qwen2.5-7B for
the in-place suspend/resume cycles. In the suspend step, document creating the
GPU map file with nvsnap-gpu-suspend gpus redirected to /ckpt/<id>/gpus so it
exists for the CRIU example.
Review comments at @src/compute-plane-services/nvsnap/scripts/build-agent.sh:
- Line 214: Update the gpushare copy step in build-agent.sh to copy source files
without carrying over locally built libnvsnap_gpushare.so or nvsnap-gpu-suspend,
so make rebuilds the binaries for the target architecture.
Review comments at
@src/compute-plane-services/nvsnap/tests/gpushare/k8s/vllm_ckpt_cycle.sh:
- Around line 41-51: Add an EXIT trap around the suspended interval in the cycle
script so failures after `suspend` automatically attempt to resume the
processes; clear the trap once the normal `resume` in the cycle completes.
Anchor the change to the `suspend` and `resume` commands, and ensure cleanup
failures do not mask the original failure.
Review comments at
@src/compute-plane-services/nvsnap/tests/gpushare/k8s/vllm_criu_bench.sh:
- Line 21: Update the script’s `set -uo pipefail` to enable errexit so failures
in suspend, stop, tar, and resume halt execution; explicitly guard any commands
that are allowed to fail so they do not trigger an unintended exit.
Review comments at
@src/compute-plane-services/nvsnap/tests/gpushare/k8s/vllm-criu.yaml:
- Line 4: Update the usage comment in the vLLM CRIU manifest to reference the
script that uses it, tests/gpushare/k8s/vllm_criu_bench.sh, instead of the
nonexistent vllm_criu_migrate.sh. Preserve the instruction to run
criu-build.yaml on the node first.
Review comments at
@src/compute-plane-services/nvsnap/tests/gpushare/k8s/vllm-tp2.yaml:
- Around line 7-8: Update the usage comment in the vllm-tp2 configuration so
both example commands use the files’ actual tests/gpushare/k8s/ paths.
Review comments at
@src/compute-plane-services/nvsnap/tests/gpushare/test_checkpoint_nccl.c:
- Around line 284-287: Update the fork loop in the test setup to detect fork()
failures and enter cleanup immediately; track successfully spawned child
processes and make the fail cleanup signal only those children, avoiding unset
or negative pids.
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src/compute-plane-services/nvsnap/docker/agent/Dockerfile.basesrc/compute-plane-services/nvsnap/docker/agent/gpushare/Makefilesrc/compute-plane-services/nvsnap/docker/agent/gpushare/gpushare.csrc/compute-plane-services/nvsnap/docker/agent/gpushare/gpushare.hsrc/compute-plane-services/nvsnap/docker/agent/gpushare/nvsnap-gpu-suspend.csrc/compute-plane-services/nvsnap/docs/GPUSHARE.mdsrc/compute-plane-services/nvsnap/scripts/build-agent.shsrc/compute-plane-services/nvsnap/scripts/versions.shsrc/compute-plane-services/nvsnap/tests/gpushare/Makefilesrc/compute-plane-services/nvsnap/tests/gpushare/k8s/criu-build.yamlsrc/compute-plane-services/nvsnap/tests/gpushare/k8s/dump_evict.pysrc/compute-plane-services/nvsnap/tests/gpushare/k8s/vllm-criu.yamlsrc/compute-plane-services/nvsnap/tests/gpushare/k8s/vllm-tp2.yamlsrc/compute-plane-services/nvsnap/tests/gpushare/k8s/vllm_ckpt_cycle.shsrc/compute-plane-services/nvsnap/tests/gpushare/k8s/vllm_criu_bench.shsrc/compute-plane-services/nvsnap/tests/gpushare/k8s/vllm_query.pysrc/compute-plane-services/nvsnap/tests/gpushare/test_checkpoint_nccl.csrc/compute-plane-services/nvsnap/tests/gpushare/test_cumem_release.csrc/compute-plane-services/nvsnap/tests/gpushare/test_feature_restore.csrc/compute-plane-services/nvsnap/tests/gpushare/test_ipc_release.csrc/compute-plane-services/nvsnap/tests/gpushare/test_ipc_share.c
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…ed between processes cuda-checkpoint cannot checkpoint a process that maps GPU memory imported from another process, so multi-GPU (tensor-parallel) workloads only checkpointed with NCCL P2P/NVLS, CUDA IPC (vLLM custom all-reduce) and friends disabled, at a cost in serving throughput. Import libnvsnap_gpushare.so, an LD_PRELOAD shim that tracks that memory, releases it before the driver checkpoint and re-creates it at the same virtual addresses after restore (cuMem imports, NVLS multicast objects, CUDA IPC on cuMem, fabric handles, page-locked host memory), and nvsnap-gpu-suspend, which drives it and the CUDA checkpoint API. For CRIU, GPU memory the shim saves goes to a content-addressed chunk store (weights stored once across checkpoints, zero chunks skipped, O_DIRECT, fdatasync before rename) with an optional node-local cache, keeping it out of the CRIU image. - docker/agent/gpushare: shim, tool, Makefile; built in a new CUDA 13 stage of Dockerfile.base (amd64 and arm64) into /criu-bundle; base image v0.0.23. - tests/gpushare: GPU tests and Kubernetes scripts (in-place cycles, full CRIU checkpoint/restore benchmark). - docs/GPUSHARE.md. No change to the agent, webhook or server. Validated with vLLM 0.20.0 at default flags, Qwen2.5-72B TP=4 on GB300 (driver 610.57.04): checkpoint on one node, restore on another from a PVC in 87.6 s new pod to first token (about 56 s with the node cache prefetched), output identical; a cold start with the model download took 1350 s. Relates to #2299 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Balaji Ganesan <bganesan@nvidia.com>
Shim and tool: - Authenticate the control socket with SO_PEERCRED. Abstract sockets have no permissions, so a sidecar or, with hostNetwork, any process on the node could request exports of GPU memory, aim release at any path, or hang the workload with quiesce. The control thread now serves only peers in its pid namespace running as root or as its user. Clients (the shim and nvsnap-gpu-suspend) talk only to a socket owned by the pid in its name. - Name chunk temp files randomly and create them with O_EXCL, in the shim and in cache-prefetch: writers in other pods share pids and could truncate each other's temp file under a trusted hash. - Multi-GPU processes: follow cuCtxEnablePeerAccess and cuCtxDisablePeerAccess and grant peers cuMemSetAccess on the cuMem memory behind cuMemAlloc (and on memory opened through CUDA IPC), for allocations made before and after, and when re-creating them after a restore. Save and load each allocation on its own device. - Give "load <cache>" the 3600 s timeout that bare "load" had. - Fall back to buffered I/O when a filesystem accepts O_DIRECT at open but fails the read or write with EINVAL. - Keep cache fills off the restore's critical path: a load that misses the cache no longer writes it; cache-prefetch fills it. - release creates the store directory; abort on allocation failure in the shim's tables; reject a zero allocation granularity. Build: copy only gpushare sources into the base image build context, so locally built binaries cannot be packaged. Tests: - test_multi_gpu: one process, two GPUs with peer access, through two suspend/resume rounds (host memory, chunk store), a buffer allocated after restore, and disabling and enabling peer access again. The previous shim faulted on the first peer write. - The k8s manifests take libnvsnap_gpushare.so and nvsnap-gpu-suspend from the agent base image's /criu-bundle instead of building them; fix stale paths; size vllm-tp2's memory limit for GB300. - vllm_criu_bench.sh stops on any failed step and times out its waits; vllm_ckpt_cycle.sh resumes the workload if a step fails while it is suspended; test_checkpoint_nccl no longer signals pid -1 when fork fails. Docs: control socket access, per-tenant stores (the chunk hash is not cryptographic), store garbage collection and hostNetwork limits, creating the --gpu-map file, results restated per model. Validated on GB300 (driver 610.57.04) and RTX PRO 6000 (x86, driver 580): GPU tests pass; vLLM 0.20.0 Qwen2.5-7B TP=4 in-place 3/3 cycles; Qwen2.5-72B TP=4 checkpoint on one node and restore on another from a PVC in 87.8 s new pod to first token, 66.7 s from the node cache, output identical. Relates to #2299 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Balaji Ganesan <bganesan@nvidia.com>
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The base image I tested the binaries from the published image.
Notes for the agent integration:
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…ants The chunk store's requirement is about who can write to it, not about tenants: a store written only by the checkpointed pod and mounted read-only by the pods restored from it adds no trust beyond the checkpoint itself, which fits checkpoints shared read-only across namespaces. State that, and that the node cache is optional and, if used, needs a directory per store or a trusted filler. Relates to #2299 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Balaji Ganesan <bganesan@nvidia.com>
…ap/criu-v2-only Signed-off-by: Balaji Ganesan <bganesan@nvidia.com> # Conflicts: # src/compute-plane-services/nvsnap/cmd/restore-entrypoint/BUILD.bazel # src/compute-plane-services/nvsnap/internal/agent/BUILD.bazel # src/compute-plane-services/nvsnap/internal/criu/BUILD.bazel # src/compute-plane-services/nvsnap/internal/webhook/BUILD.bazel
The Bazel BUILD files in nvsnap were not regenerated as packages and files changed on this stacked branch; check-gazelle only runs on pull requests to main, so the drift was not reported. Co-Authored-By: Balaji Ganesan <bganesan@nvidia.com> Signed-off-by: Balaji Ganesan <bganesan@nvidia.com>
Signed-off-by: Balaji Ganesan <bganesan@nvidia.com>
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Critical review of head 52113b0. Five inline findings cover lock synchronization, resume recovery, state-file safety, release ordering, and access-permission tracking. Validation used extracted PR functions with mocked CUDA calls and an isolated filesystem reproduction. GPU tests were not run.
| jobs[i].ret = 2; /* 2 = thread running */ | ||
| } | ||
| for (int i = 0; i < n; i++) { | ||
| if (jobs[i].ret != 2) continue; | ||
| pthread_join(jobs[i].thread, NULL); | ||
| if (jobs[i].ret != 0) failures++; |
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[P1] Track thread creation separately from the lock result
jobs[i].ret is both the worker result and the thread-started marker, and both threads write it without synchronization. If a worker finishes with -1 before the join loop reaches it, ret != 2 skips the join and the failed lock is never counted. The parent can also overwrite a completed result with 2 after pthread_create(). This lets lock_all() report success while a rank remains unlocked. A CPU-only reproduction using the extracted functions and a mocked failing lock reported success in 20/20 runs. Keep a separate started flag, join every successfully created thread, and inspect its result only after joining.
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Fixed in 45a3b10. lock_job has a separate started flag. lock_all joins every started thread and reads ret only after the join, so a failed lock is always counted. each_par and ctl_all_par already read results only after joining.
| return ok_stop ? 0 : 1; | ||
| } | ||
| printf("resume requested (signal %d)\n", sig); | ||
| if (full_restore(pids, n) == 0 && remap_all(pids, n) >= 0) break; |
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[P1] Allow resume to retry after driver restore has completed
full_restore() unlocks every rank before remap_all() runs. If loading a chunk or remapping then fails, the holder keeps the CPU threads frozen, but their CUDA state is already RUNNING. The next resume calls full_restore() again, which rejects RUNNING at lines 430-435, so it never reaches remap_all() even after the underlying problem is fixed. resume_unheld() has the same issue. A CPU-only reproduction confirmed that a successful restore leaves both ranks RUNNING and the next restore returns failure. Track completed phases and permit retrying the unfinished remap phase without repeating driver restore/unlock.
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Fixed in 45a3b10. full_restore treats RUNNING pids as already restored and unlocked, and unlocks only LOCKED ones. A retried resume therefore reaches remap, and since fbb9e9b remap/resume restore only what is still dropped, repeating them is safe. test_release_rollback case 5 covers it: the chunk store is moved away, resume fails after the driver restore, then the store is put back and a second resume completes.
| if (child == 0) { | ||
| close(fds[0]); | ||
| setsid(); | ||
| int fd = open(log, O_WRONLY | O_CREAT | O_TRUNC, 0600); |
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[P1] Secure the predictable state directory before opening files
When this tool runs as root in a filesystem shared with an unprivileged process, that process can precreate /tmp/nvsnap-gpu-suspend and place a <pid>.log symlink targeting another file. The mkdir() result at line 852 is ignored, and this open(O_TRUNC) follows the symlink with the tool's privileges. A safe scratch-directory reproduction confirmed that the target file is truncated. The holder/result files also use path-based fopen() without verifying the directory. Validate ownership and permissions of an existing state directory, reject symlink directories, and use directory-relative opens that reject symlinks for all state files.
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Fixed in 45a3b10. The tool uses /tmp/nvsnap-gpu-suspend only if it is a real directory owned by its euid with mode 0700, opened with O_DIRECTORY|O_NOFOLLOW and checked with fstat. Every state file is opened, tested and removed relative to that directory fd (openat/faccessat/unlinkat) with O_NOFOLLOW. Checked in a pod: a directory owned by another uid, a symlink to another directory and a world-writable mode are all refused, and nothing is written through the symlink.
| char release[600] = "release"; | ||
| if (store_dir) snprintf(release, sizeof(release), "release %s %s%s%s", store_dir, ckpt_dir, | ||
| cache_dir ? " " : "", cache_dir ? cache_dir : ""); | ||
| if (shared && ctl_all_par(pids, n, release) < 0) { |
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[P1] Block memory operations before releasing GPU mappings
This releases shared mappings and saves/unmaps the shim's allocations before taking the driver lock or freezing application threads. Quiescence closes the kernel/graph launch gate and drains existing GPU work, but the shim does not gate copies or memsets. An application thread can therefore submit a new transfer after the synchronization completes, while release is saving or unmapping its source/destination. That can produce inconsistent checkpoint contents or invalid-pointer failures under active traffic. Establish a barrier that also covers those operations before release, while keeping the control and CUDA restore threads runnable. This is a static finding; it needs a GPU stress test with concurrent transfers during suspend.
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Confirmed on GPUs, and fixed in 45a3b10. test_checkpoint_nccl (4 ranks, GB300) failed in about 4 of 5 runs before this: a rank died during release. Copies, memsets, peer and 2D/3D copies, stream memory operations and cuLaunchHostFunc now wait in a second gate, under both default and per-thread (_ptds/_ptsz) entry points. quiesce closes the launch gate, drains the GPU, closes the memory gate, waits for calls inside it, then drains again. Holding copies from the start deadlocked instead, because NCCL's proxy thread issues copies its in-flight kernels need. Result: 8/8 runs pass. Array copies, managed prefetch and batched copies are not held; that's documented.
| memcpy(maps[i].acc, d, n * sizeof(*d)); | ||
| maps[i].nacc = n; |
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[P2] Preserve access grants from earlier cuMemSetAccess calls
cuMemSetAccess() updates permissions for the locations specified in that call; the descriptor array is not a complete replacement for all existing permissions. For example, granting GPU 0 access and then granting GPU 1 access in a separate call leaves both devices accessible before suspend, but this code saves only GPU 1. do_remap() then reapplies only GPU 1's descriptor, so GPU 0 loses access after restore. The multicast branch has the same problem. A CPU-only reproduction of this wrapper confirmed the lost owner permission. Merge saved permissions by location and account for the affected address range. CUDA contract: https://docs.nvidia.com/cuda/cuda-driver-api/cuda_driver_api/group__CUDA__VA.html
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Fixed in 45a3b10. cuMemSetAccess descriptors are merged per location (acc_merge): later calls add or update locations, and PROT_NONE removes one. test_multi_gpu covers it with an imported allocation given access by GPU 0 and GPU 1 in two separate calls; both keep access across host-memory and chunk-store restores.
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Found while running the nvsnap integration (#2318) end to end: the rollback after a partially failed Trigger: Same on the TP=4 run (pids 697-700). Suggested fix: have Two smaller requests from the same run:
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When "release" failed partway, the tool's rollback ("load", "remap",
"resume") restored everything as if all of it had been dropped: remap
re-registered page-locked host buffers that were never unregistered and
failed with CUDA_ERROR_HOST_MEMORY_ALREADY_REGISTERED, leaving the
workload's state unclear. Imports, multicast mappings, binds and objects
were likewise marked dropped even when the driver call failed, and
exported fds were closed.
- release marks each object dropped only once it is: unmapped imports
(new), released imports, multicast mappings, binds and objects, host
buffers (new). remap and resume restore exactly those, including an
import unmapped but still held. Exported fds are closed only after a
complete release. The error names the step that failed.
- The tool reports whether a rollback worked, and rollback counts pids
it could not bring back to RUNNING.
- release creates --ckpt-dir as it does the store; gpus takes an output
file.
test_release_rollback makes suspend fail before anything is released,
partway (an allocation cannot be saved, host buffers still registered)
and after a complete release (the driver lock fails), checks the
workload works as before each time, then checkpoints normally with an
import its exporter freed. With the previous code each failure ended in
ALREADY_REGISTERED.
Relates to #2299
Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Signed-off-by: Balaji Ganesan <bganesan@nvidia.com>
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Thanks, reproduced and fixed in fbb9e9b. It was broader than host buffers.
Each time it checks that the workload works as before, then runs a normal checkpoint that includes an import its exporter freed. With the previous code, every failure ended in Validated on GB300 (driver 610):
My first version of the fix had a bug of its own. A mapping whose exporter had freed the memory kept its "unmapped" mark, and the rollback path then re-mapped it with a stale handle, which crashed. vLLM caught it (3 such mappings per rank). It's fixed in the same commit and covered by the test.
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Review findings on the gpushare shim and nvsnap-gpu-suspend: - Hold copies, memsets and stream memory operations during a checkpoint, not only launches: an app thread past the drain could touch memory "release" was freeing, and a rank could crash mid-release (test_checkpoint_nccl failed about 4 runs in 5). They wait in a second gate that closes only after the GPU drained, then the GPU is drained again: NCCL's proxy thread issues copies its kernels in flight need. Synchronous calls are held under their per-thread (_ptds) entry points too. - lock_all: track thread creation apart from the lock result, join every started thread and read its result only after the join; a failed lock could be reported as success. - resume can be retried after the driver restore succeeded and a later step failed: full_restore treats RUNNING pids as done and unlocks only LOCKED ones; remap and resume restore only what is still dropped. - State files: use /tmp/nvsnap-gpu-suspend only if it is a directory of the tool's user with mode 0700, and open files in it relative to it without following symlinks, so another user cannot redirect the tool's writes. - cuMemSetAccess grants are merged per location instead of replaced by the last call, so remap grants every device that had access. Tests: test_release_rollback adds a resume that fails after the driver restore (the chunk store is missing) and succeeds when retried; test_multi_gpu adds an imported allocation given access by two devices in separate cuMemSetAccess calls. On GB300 (driver 610): test_checkpoint_nccl 8/8 runs, the other GPU tests pass, vLLM Qwen2.5-7B TP=4 3/3 in-place cycles with identical output; the state directory refuses a foreign owner, a symlink and a world-writable mode. Docs: the calls the gate holds, the state directory rule, and that on x86 with driver 580.126.16 the driver's restore of processes sharing GPU memory fails (vLLM TP=2), with or without the shim's steps. Relates to #2299 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Balaji Ganesan <bganesan@nvidia.com>
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The review fixes are in Validated on GB300 (driver 610.57.04):
A new known limit, now in GPUSHARE.md: on x86 with driver 580.126.16 (RTX PRO 6000), the driver's own restore of vLLM TP=2 workers fails ( |
FlashInfer's all-reduce fusion (used by vLLM on H100) exports its buffer as a POSIX fd, sends that fd to itself along with its peers', and closes neither copy. Those /dev/nvidiactl fds survive the CUDA checkpoint, pin the pre-checkpoint memory, and make the CRIU dump of a TP=4 vLLM pod fail. After a successful release, every fd in the process that is the same open file as one of its exports is now pointed at /dev/null with dup3. The fd numbers stay valid for the app to close. test_export_copies reproduces the pattern: the old shim leaves two NVIDIA fds after suspend, the new one none, and the memory, both fds and a re-export work after resume. Docs: driver 610 is now the minimum. Driver 580 cannot restore multicast objects, which NCCL NVLS, PyTorch symmetric memory and FlashInfer use on NVSwitch systems. Validated: GB300 (driver 610) all gpushare GPU tests; H100 (driver 580, multicast users off) vLLM TP=4 CRIU dump and restore into a new pod with identical output. Relates to #2299 Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com> Signed-off-by: Balaji Ganesan <bganesan@nvidia.com>
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Pushed e5d8d1a: fix for the TP=4 CRIU dump failing on H100 with NVIDIA control-device fds still open after suspend. Cause: FlashInfer's all-reduce fusion (enabled by vLLM on H100) exports its workspace buffer as a POSIX fd, sends it to itself along with its peers' fds, and never closes either copy. That leaves 6 Fix: after a successful Driver minimum is now 610. Driver 580 can't restore multicast objects ( Validation:
The fix isn't in a published base image yet; v0.0.24 predates it. 🤖 Generated with Claude Code |
2 participants
TL;DR
This PR imports gpushare, which lets tensor-parallel workloads be checkpointed and restored with their default NCCL and engine settings. It has two parts:
libnvsnap_gpushare.sois an LD_PRELOAD shim. It releases GPU memory that processes share (NCCL P2P and NVLS, CUDA IPC, fabric handles, pinned host memory) before the driver checkpoint, and re-creates it at the same addresses after restore.nvsnap-gpu-suspenddrives the shim and the CUDA checkpoint API.GPU memory saved for CRIU goes to a content-addressed chunk store, with an optional node-local cache.
This is a self-contained import. It does not change the agent, the webhook or the server.
Additional Details
cuda-checkpointcannot checkpoint a process that maps GPU memory imported from another process. Today multi-GPU checkpoint/restore therefore only works with these transports disabled: NCCL P2P/NVLS, vLLM custom all-reduce, and so on. That costs serving throughput.What the import contains (all paths under
src/compute-plane-services/nvsnap/):docker/agent/gpushare/: the shim (gpushare.c,gpushare.h), the tool (nvsnap-gpu-suspend.c), and a Makefile.docker/agent/Dockerfile.base: a newgpushare-builderstage that builds both binaries into/criu-bundle/.nvidia/cuda:13.0.3-devel-ubuntu22.04, because the tool's--gpu-mapneeds CUDA 13 headers (CUcheckpointGpuPair).scripts/build-agent.shcopies the gpushare sources, and only those, into the build context.scripts/versions.shbumps the base image tov0.0.23.tests/gpushare/: six GPU tests with a Makefile, plusk8s/scripts for an in-place suspend/resume cycle test and a full CRIU checkpoint/restore benchmark with a timing breakdown. The manifests take both binaries from the base image's/criu-bundle.docs/GPUSHARE.md: the protocol, usage, chunk store and cache, limits, and validation results.How the pieces work together:
@nvsnap-gpushare.<pid>.nvsnap-gpu-suspendsends it, in order:quiesce, thenrelease(sent to every pid at once), then the driver checkpoint (all pids in parallel).load(all at once), thenremapandresume.--store/--ckpt-dirwrite the saved memory to the chunk store. Chunks are 64 MiB, written with O_DIRECT, synced with fdatasync, then renamed into place. Zero chunks are skipped, and chunks already present in the store are not written again.--cacheadds a node-local copy of the store. Saves write through to it and loads read it first.cache-prefetchfills it, so a cache miss during a restore never waits on cache writes.cache-gcevicts from it.SO_PEERCRED). It serves only callers in the workload's pid namespace that run as root or as the workload's user. Clients talk only to the process a socket is named for.cuCtxEnablePeerAccessand grants peers access to the cuMem memory it puts behindcuMemAlloc.Limitations:
nvsnap-gpu-suspendmust run in the workload's pid and network namespaces.cache-gccovers the node cache only.Left to nvsnap's side:
This PR is stacked on #2261 (
nvsnap/criu-v2-only), which retires the old injection stack. The second commit addresses the review findings.For the Reviewer
Files to look at closely:
docker/agent/gpushare/gpushare.c, especially the release/remap of imports and multicast,valloc_drop/valloc_restore, and the chunk store.docker/agent/gpushare/nvsnap-gpu-suspend.c(the holder, parallel driver checkpoint/restore, and cache commands).Dockerfile.basestage.nvsnap/CONTRIBUTING.mdsays "There is no LD_PRELOAD injection stack any more". The shim is LD_PRELOAD, but this PR adds no injection: placement is left to the webhook.For QA
Both binaries build without warnings (
-Wall -Wextra -Werror) on amd64 and arm64.Dockerfile.basebuilds for both architectures.Validated on this branch with vLLM 0.20.0 at default flags:
GPU tests (
tests/gpushare/) pass on GB300 (arm64, driver 610.57.04) and on RTX PRO 6000 (x86, driver 580).test_multi_gpuis new. The previous shim faulted on its first peer write.test_ipc_releaseandtest_cumem_releaseprobe the driver without the shim.Qwen2.5-7B, TP=4, in place on GB300: 3 out of 3 suspend/resume cycles passed with identical output. Suspend took about 6.5 s, resume about 5.9 s.
Qwen2.5-72B, TP=4, on GB300, checkpointed on one node and restored on another, with the store on a PVC and the cache on local NVMe:
The base image
nvsnap-agent-base:v0.0.23is published for amd64 and arm64. Its binaries passed the TP=2 cycle test on GB300 (see the comment below).Issues
Relates to #2299
Checklist
🤖 Generated with Claude Code
Summary by CodeRabbit
New Features
Documentation
Testing