jgrusewski 5275932f4c guard+cleanup(cuda): DtoD-via-pinned pre-commit guard + delete orphan HER ...

Two related changes installing the structural guard against the SP6 Pearl 5
IQN τ failure mode (root cause fixed at facbf76eb for that one site) and
removing the only remaining orphan callers of the broken pattern.

The bug class. The mapped_pinned::{upload,clone_to_device}_{f32,i32}_via_pinned
helpers are named to suggest "no HtoD per feedback_no_htod_htoh_only_mapped_pinned"
but their bodies do MappedXBuffer::new() + memcpy_dtod_async() +
stream.synchronize(). The DtoD copy and synchronize are both forbidden
inside CUDA Graph capture (CUDA_ERROR_STREAM_CAPTURE_INVALIDATED) and add a
host stall otherwise. The canonical pattern is MappedXBuffer stored directly
+ write_from_slice + kernel reads via .dev_ptr, used by SP4 portfolio_state
and SP6 IQN τ at facbf76eb.

Guard. New check_no_dtod_via_pinned in pre-commit-hook.sh rejects any
staged .rs file calling upload_(f32|i32)_via_pinned or
clone_to_device_(f32|i32)_via_pinned, except mapped_pinned.rs itself. Per
feedback_no_hiding: no suppression marker. Also fixes a pre-existing
silent-skip bug: the gpu-hotpath-guard.sh invocation used
$(cd "$(dirname "$0")" && pwd) which resolved to .git/hooks/ (the symlink's
directory) instead of scripts/, so the guard never ran. Replaced with
readlink -f "$0" + an explicit "guard missing" error branch — silent skip
is worse than no guard.

Orphan deletion. gpu_her.rs carried legacy relabel_batch, generate_random_donors
(CPU), HerBatch, slice_clone_f32, slice_clone_i32 — zero production callers
(verified via grep). Production uses relabel_batch_with_strategy +
generate_random_donors_gpu. The orphan held the only upload_i32_via_pinned
callers in the codebase; per feedback_no_hiding the right fix is delete.

Scope. Eliminates 2 of 47 production *_via_pinned call sites. Remaining 45
across 14 files are cold-path init — graph-capture-fragile and host-stalling
but not breaking operationally. Guard enforces no new calls; existing 45
migrate in subsequent atomic per-buffer commits. After all 45 are converted,
the four helpers themselves get deleted from mapped_pinned.rs.

Validation. Smoke smoke-test-82fjk at facbf76eb succeeded — magnitude
differentiation restored (q_full=0.462 > q_half=0.409 > q_quarter=0.350 vs
baseline frozen Pascal-triangle 0.225/0.280/0.495), eval distribution
unfrozen (eq=0.596, eh=0.404, ef=0.000 vs baseline single-action collapse).

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

2026-05-02 10:12:23 +02:00

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