ChatGPT's diagnostic changes to address TLS_SLL_HDR_RESET issue.
Current status: Partial mitigation, but root cause remains.
Changes Applied:
1. SuperSlab Registry Fallback (hakmem_super_registry.h)
- Added legacy table probe when hash map lookup misses
- Prevents NULL returns for valid SuperSlabs during initialization
- Status: ✅ Works but may hide underlying registration issues
2. TLS SLL Push Validation (tls_sll_box.h)
- Reject push if SuperSlab lookup returns NULL
- Reject push if class_idx mismatch detected
- Added [TLS_SLL_PUSH_NO_SS] diagnostic message
- Status: ✅ Prevents list corruption (defensive)
3. SuperSlab Allocation Class Fix (superslab_allocate.c)
- Pass actual class_idx to sp_internal_allocate_superslab
- Prevents dummy class=8 causing OOB access
- Status: ✅ Root cause fix for allocation path
4. Debug Output Additions
- First 256 push/pop operations traced
- First 4 mismatches logged with details
- SuperSlab registration state logged
- Status: ✅ Diagnostic tool (not a fix)
5. TLS Hint Box Removed
- Deleted ss_tls_hint_box.{c,h} (Phase 1 optimization)
- Simplified to focus on stability first
- Status: ⏳ Can be re-added after root cause fixed
Current Problem (REMAINS UNSOLVED):
- [TLS_SLL_HDR_RESET] still occurs after ~60 seconds of sh8bench
- Pointer is 16 bytes offset from expected (class 1 → class 2 boundary)
- hak_super_lookup returns NULL for that pointer
- Suggests: Use-After-Free, Double-Free, or pointer arithmetic error
Root Cause Analysis:
- Pattern: Pointer offset by +16 (one class 1 stride)
- Timing: Cumulative problem (appears after 60s, not immediately)
- Location: Header corruption detected during TLS SLL pop
Remaining Issues:
⚠️ Registry fallback is defensive (may hide registration bugs)
⚠️ Push validation prevents symptoms but not root cause
⚠️ 16-byte pointer offset source unidentified
Next Steps for Investigation:
1. Full pointer arithmetic audit (Magazine ⇔ TLS SLL paths)
2. Enhanced logging at HDR_RESET point:
- Expected vs actual pointer value
- Pointer provenance (where it came from)
- Allocation trace for that block
3. Verify Headerless flag is OFF throughout build
4. Check for double-offset application in conversions
Technical Assessment:
- 60% root cause fixes (allocation class, validation)
- 40% defensive mitigation (registry fallback, push rejection)
Performance Impact:
- Registry fallback: +10-30 cycles on cold path (negligible)
- Push validation: +5-10 cycles per push (acceptable)
- Overall: < 2% performance impact estimated
Related Issues:
- Phase 1 TLS Hint Box removed temporarily
- Phase 2 Headerless blocked until stability achieved
🤖 Generated with Claude Code (https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
Problem: hak_core_init.inc.h references KPI measurement variables
(g_latency_histogram, g_latency_samples, g_baseline_soft_pf, etc.)
but hakmem.c was including hak_kpi_util.inc.h AFTER hak_core_init.inc.h,
causing undefined reference errors.
Solution: Reorder includes so hak_kpi_util.inc.h (definition) comes
before hak_core_init.inc.h (usage).
Build result: ✅ Success (libhakmem.so 547KB, 0 errors)
Minor changes:
- Added extern __thread declarations for TLS SLL debug variables
- Added signal handler logging for debug_dump_last_push
- Improved hakmem_tiny.c structure for Phase 2 preparation
🤖 Generated with Claude Code + Task Agent
Co-Authored-By: Gemini <gemini@example.com>
Co-Authored-By: Claude <noreply@anthropic.com>
This commit introduces a comprehensive tracing mechanism for allocation failures within the Adaptive Cache Engine (ACE) component. This feature allows for precise identification of the root cause for Out-Of-Memory (OOM) issues related to ACE allocations.
Key changes include:
- **ACE Tracing Implementation**:
- Added environment variable to enable/disable detailed logging of allocation failures.
- Instrumented , , and to distinguish between "Threshold" (size class mismatch), "Exhaustion" (pool depletion), and "MapFail" (OS memory allocation failure).
- **Build System Fixes**:
- Corrected to ensure is properly linked into , resolving an error.
- **LD_PRELOAD Wrapper Adjustments**:
- Investigated and understood the wrapper's behavior under , particularly its interaction with and checks.
- Enabled debugging flags for environment to prevent unintended fallbacks to 's for non-tiny allocations, allowing comprehensive testing of the allocator.
- **Debugging & Verification**:
- Introduced temporary verbose logging to pinpoint execution flow issues within interception and routing. These temporary logs have been removed.
- Created to facilitate testing of the tracing features.
This feature will significantly aid in diagnosing and resolving allocation-related OOM issues in by providing clear insights into the failure pathways.
- Root cause: header-based class indexing (HEADER_CLASSIDX=1) wrote a 1-byte
header during allocation, but linear carve/refill and initial slab capacity
still used bare class block sizes. This mismatch could overrun slab usable
space and corrupt freelists, causing reproducible SEGV at ~100k iters.
Changes
- Superslab: compute capacity with effective stride (block_size + header for
classes 0..6; class7 remains headerless) in superslab_init_slab(). Add a
debug-only bound check in superslab_alloc_from_slab() to fail fast if carve
would exceed usable bytes.
- Refill (non-P0 and P0): use header-aware stride for all linear carving and
TLS window bump operations. Ensure alignment/validation in tiny_refill_opt.h
also uses stride, not raw class size.
- Drain: keep existing defense-in-depth for remote sentinel and sanitize nodes
before splicing into freelist (already present).
Notes
- This unifies the memory layout across alloc/linear-carve/refill with a single
stride definition and keeps class7 (1024B) headerless as designed.
- Debug builds add fail-fast checks; release builds remain lean.
Next
- Re-run Tiny benches (256/1024B) in debug to confirm stability, then in
release. If any remaining crash persists, bisect with HAKMEM_TINY_P0_BATCH_REFILL=0
to isolate P0 batch carve, and continue reducing branch-miss as planned.
