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Fix GPU segfault: switch tests to V100, add CUDA pinning for docs#127

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ChrisRackauckas-Claude wants to merge 14 commits intoSciML:mainfrom
ChrisRackauckas-Claude:fix-gpu-segfault-v100
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Fix GPU segfault: switch tests to V100, add CUDA pinning for docs#127
ChrisRackauckas-Claude wants to merge 14 commits intoSciML:mainfrom
ChrisRackauckas-Claude:fix-gpu-segfault-v100

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Summary

This PR addresses the GPU test segfault (signal 11) and documentation build failure reported in ChrisRackauckas/InternalJunk#23.

Changes

GPU Tests

  • Switch from gpu-t4 to gpu-v100 runner — The T4 runner was experiencing segfaults in Julia's codegen (emit_unboxed_coercion) during the DeepBSDE test. The crash happens during Zygote gradient computation with complex types. The V100 with 32GB VRAM (vs T4's shared 15GB) should provide enough headroom for the heavy JIT compilation.

Documentation

  • Add LocalPreferences.toml to docs/ directory to pin CUDA runtime to v12.6 and disable forward-compat driver
  • Add CUDA_Driver_jll and CUDA_Runtime_jll to docs/Project.toml
  • Widen CUDA compat to 4, 5 to allow broader version range

The documentation was failing on demeter4 V100 runners because CUDA_Driver_jll v13+ drops compute capability 7.0 (V100) support. The LocalPreferences.toml fix follows the pattern established in OrdinaryDiffEq.jl.

Test Details

The segfault occurred at:

[1006912] signal 11 (1): Segmentation fault
in expression starting at .../test/DeepBSDE.jl:19
emit_unboxed_coercion at .../julia-release-1-dot-12/src/intrinsics.cpp:394 [inlined]
emit_unbox at .../julia-release-1-dot-12/src/intrinsics.cpp:458

This is a Julia compiler crash during codegen, triggered by heavy AD compilation through Zygote/Flux in the DeepBSDE solver. Moving to V100 provides more resources for compilation.

References

  • Fixes: ChrisRackauckas/InternalJunk#23
  • Related: ChrisRackauckas/InternalJunk#19 (CUDA compatibility pattern)

ChrisRackauckas and others added 4 commits March 19, 2026 08:42
- Switch GPU tests from gpu-t4 to gpu-v100 to address Julia codegen
  segfault (signal 11) during DeepBSDE test compilation
- Add LocalPreferences.toml to docs/ with CUDA 12.6 runtime pinning
  and driver forward-compat disabled for V100 compatibility
- Add CUDA_Driver_jll and CUDA_Runtime_jll to docs/Project.toml
- Widen CUDA compat to '4, 5' in docs/Project.toml

The T4 runner was experiencing segfaults in Julia's codegen during
heavy AD (Zygote) compilation. V100 with more VRAM should resolve
this. Docs segfault was caused by CUDA_Driver_jll v13+ dropping
compute capability 7.0 (V100) support.

Fixes: ChrisRackauckas/InternalJunk#23
- Add Optimisers.jl as a dependency
- Add _copy and _get_eta overloads for Optimisers.AbstractRule
- Add constructor for Optimisers.jl optimizers
- Update docs to use Flux.Optimise.Adam explicitly
The two separate constructors for Flux.Optimise and Optimisers.jl were
causing a method overwriting error during precompilation. Merged into
a single constructor that works with both optimizer types since the
_get_eta helper already dispatches correctly for both types.
- Pin GPU tests and docs to Julia 1.10 to avoid Julia 1.12 codegen
  segfault in emit_unboxed_coercion during Zygote compilation
- Add julia-actions/setup-julia step to FormatCheck workflow (runic
  requires Julia but it was not being installed)
- Add root LocalPreferences.toml to pin CUDA runtime for GPU tests
  (CUDA_Driver_jll v13+ drops V100 compute capability 7.0 support)

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@ChrisRackauckas-Claude
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CI Fix Attempt (commit 8c5ec18)

Addressing three CI failures:

  1. runic (FormatCheck.yml): Added missing julia-actions/setup-julia@v2 step before runic-action. The action requires Julia but it wasn't being installed.

  2. GPU Tests & Documentation (GPU.yml): Pinned Julia version from "1" (1.12.5) to "1.10" for both jobs. The segfault (signal 11) occurs in Julia 1.12's codegen (emit_unboxed_coercion) during Zygote/Flux compilation — this is a Julia compiler bug, not a GPU memory issue. Julia 1.10 is stable and passes CPU tests.

  3. GPU Tests CUDA pinning: Added root LocalPreferences.toml (matching the existing docs/LocalPreferences.toml) to pin CUDA runtime to v12.6 and disable forward-compat driver, since CUDA_Driver_jll v13+ drops compute capability 7.0 (V100) support.

ChrisRackauckas and others added 2 commits March 19, 2026 18:47
Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
Zombie Downgrade runs blocked CI queue for 50+ hours. Adding
concurrency groups ensures old runs are cancelled when new pushes
arrive. Adding 2-hour timeout to Downgrade prevents future zombies.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@ChrisRackauckas-Claude
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CI Blocked by Zombie Runs — Admin Action Needed

Two Downgrade workflow runs (IDs: 23320424953, 23320450557) have been stuck in "in_progress" state for 60+ hours. They're consuming runner slots and blocking all other CI jobs (all 5 PR checks have been "pending" for 2+ days).

Admin action needed: Please cancel these two zombie runs:

gh api -X POST repos/SciML/HighDimPDE.jl/actions/runs/23320424953/force-cancel
gh api -X POST repos/SciML/HighDimPDE.jl/actions/runs/23320450557/force-cancel

Also, there are stale queued runs from earlier pushes that can be cancelled:

gh api -X POST repos/SciML/HighDimPDE.jl/actions/runs/23320450542/cancel
gh api -X POST repos/SciML/HighDimPDE.jl/actions/runs/23320578183/cancel
gh api -X POST repos/SciML/HighDimPDE.jl/actions/runs/23320578202/cancel
gh api -X POST repos/SciML/HighDimPDE.jl/actions/runs/23320578205/cancel

The latest push (dcb2a28) adds concurrency groups to the Downgrade, SpellCheck, and FormatCheck workflows to prevent this from happening again.

… gpu]

The gpu-v100 label has no active runners, causing jobs to queue
indefinitely (9+ days). All other SciML repos (DiffEqFlux, NeuralPDE,
DeepEquilibriumNetworks) use the generic [self-hosted, Linux, X64, gpu]
label which matches available runner pools.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
@ChrisRackauckas-Claude
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CI Progress Update (commit 5fa4151)

Fixed (passing):

  • Spell Check with Typos: PASS
  • runic: PASS (setup-julia fix works)

Still running (18+ hours, likely stuck):

  • GPU Tests: in_progress on arctic1-2 since 05:37 UTC
  • Documentation: in_progress on arctic1-4 since 05:37 UTC
  • test (Core, alldeps, 1.10): in_progress on GitHub-hosted runner since 05:37 UTC

The runner label fix (gpu-v100[self-hosted, Linux, X64, gpu]) resolved the queue blocking — jobs now pick up runners immediately. However, the timeout-minutes settings (60 for GPU tests, 120 for Downgrade, 360 for docs) are not being enforced, causing jobs to become zombie runs.

The key improvements:

  1. No segfault — Julia 1.10 pin eliminates the codegen crash
  2. Runners found — standard GPU labels match the available runner pool
  3. runic passes — setup-julia step was the fix

The zombie run issue appears to be a systemic problem with how timeouts are enforced on these runners.

ChrisRackauckas and others added 7 commits March 20, 2026 03:07
Switch from generic [self-hosted, Linux, X64, gpu] to exclusive
[self-hosted, gpu-v100] tags. The generic tag shares runners with
other repos causing contention. The gpu-v100 tag provides dedicated
V100 runners with 32GB VRAM, matching SciMLSensitivity.jl's pattern.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
GPU tests failed with "Please use a device with at least capability
7.5" because CUDA_Driver_jll v13 dropped V100 (cc 7.0) support. The
LocalPreferences.toml wasn't being picked up by the test environment.

Fix by setting JULIA_CUDA_USE_COMPAT=false env var in GPU workflow to
force using the system CUDA driver instead of the bundled one. Also
add CUDA_Driver_jll and CUDA_Runtime_jll to Project.toml deps so
LocalPreferences.toml can be read.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
- Add compat bounds for CUDA_Driver_jll and CUDA_Runtime_jll in
  Project.toml (fixes Aqua deps_compat test)
- Replace deprecated ADAM() and Flux.Optimise.Adam() with Flux.Adam()
  in all doc tutorials (fixes MethodError in doc build)

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
CUDA.jl v5 doesn't support CUDA driver v13. The docs project was
loading CUDA_Driver_jll v13 despite LocalPreferences.toml. Adding
explicit compat bound to force resolver to pick v12.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
CUDA_Driver_jll versions are 12.x/13.x (matching CUDA toolkit), not
0.x. Fix docs to pin v12 (CUDA.jl v5 doesn't support v13), and fix
main Project.toml to allow both v12 and v13.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
CUDA_Driver_jll jumped from 0.13.1 to 13.2.0. Pin docs to old 0.x
versions that work with CUDA.jl v5. Main project allows both ranges.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
CUDA.jl v5 requires CUDA_Driver_jll v13 which conflicts with the V100
runner's CUDA 13 system driver (CUDA.jl v5 only supports 11.x/12.x
drivers). Doc tutorials run on CPU so GPU runners aren't needed.

Co-Authored-By: Chris Rackauckas <accounts@chrisrackauckas.com>
Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>
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2 participants