Files
hakmem/docs/analysis/debug_analysis_final_$(date +%Y%m%d_%H%M%S).md
Moe Charm (CI) a9ddb52ad4 ENV cleanup: Remove BG/HotMag vars & guard fprintf (Larson 52.3M ops/s)
Phase 1 完了:環境変数整理 + fprintf デバッグガード

ENV変数削除(BG/HotMag系):
- core/hakmem_tiny_init.inc: HotMag ENV 削除 (~131 lines)
- core/hakmem_tiny_bg_spill.c: BG spill ENV 削除
- core/tiny_refill.h: BG remote 固定値化
- core/hakmem_tiny_slow.inc: BG refs 削除

fprintf Debug Guards (#if !HAKMEM_BUILD_RELEASE):
- core/hakmem_shared_pool.c: Lock stats (~18 fprintf)
- core/page_arena.c: Init/Shutdown/Stats (~27 fprintf)
- core/hakmem.c: SIGSEGV init message

ドキュメント整理:
- 328 markdown files 削除(旧レポート・重複docs)

性能確認:
- Larson: 52.35M ops/s (前回52.8M、安定動作)
- ENV整理による機能影響なし
- Debug出力は一部残存(次phase で対応)

🤖 Generated with Claude Code

Co-Authored-By: Claude <noreply@anthropic.com>
2025-11-26 14:45:26 +09:00

3.3 KiB
Raw Blame History

Debug Analysis Final - TLS-SLL Guard Investigation

Date: 2025-11-10 Binary: out/debug/bench_fixed_size_hakmem (verbose debug build) Command: 200000 1024 128

1. Maximum Tracing Results

Key Findings:

[TLS_SLL_GUARD] splice_trav: misaligned base=0x7244b7e10009 cls=0 blk=8 off=1
[HAKMEM][EARLY SIGSEGV] backtrace (1 frames)
./out/debug/bench_fixed_size_hakmem(+0x6a5e)[0x5b4a8b13ea5e]

Critical Discovery:

  • TLS-SLL GUARDが検出 misaligned base=0x7244b7e10009
  • SPLICE_TO_SLL直後のsplice_trav操作でアライメント違反
  • これがSIGSEGVの直接原因

Analysis of misaligned address:

  • base=0x7244b7e10009 - 最後の9進数0x9が問題
  • cls=0 blk=8 off=1 - class 0, block 8, offset 1
  • 正しいはず: 0x7244b7e10000 + (8 * 256) + 1 = 0x7244b7e10081
  • 実際: 0x7244b7e10009 - 計算が間違っている!

2. No Cache Results (Frontend Disabled)

Same Pattern:

[TLS_SLL_GUARD] splice_trav: misaligned base=0x7d9100410009 cls=0 blk=8 off=1
[HAKMEM][EARLY SIGSEGV] backtrace (1 frames)
./out/debug/bench_fixed_size_hakmem(+0x6a5e)[0x622ace44fa5e]

Confirmed:

  • Frontend cacheを無効にしても問題は再現
  • TLS-SLL境界の問題であることが確定

3. Root Cause Analysis

Problem Location:

  • SPLICE_TO_SLL直後のTLS-SLL操作
  • splice_travtraverse spliceでポインタ計算が破壊されている

Calculation Error:

Expected: base + (blk * size) + off
Actual:   base + ??? = 0x7244b7e10009 (9 bytes from base)

Header Offset Confusion:

  • Class 0 (128B): header offset should be 1 byte
  • Block 8: should be at 8 * 128 = 1024 bytes from base
  • Correct address: 0x7244b7e10000 + 1024 + 1 = 0x7244b7e10401
  • Actual: 0x7244b7e10009 - 完全に間違った計算!

4. PTR_TRACE Analysis

Missing TLS Operations:

  • PTR_TRACEにtls_push/tls_pop/tls_sp_trav/tls_sp_linkが記録されていない
  • TLS-SLL GUARDが発火する段階で既にPTR_TRACEが動いていない
  • PTR_TRACEマクロ自体が問題のコードパスを通っていない

5. Recommendations

Immediate Fix:

  1. TLS-SLL splice_travのポインタ計算を修正
    • base + (blk * size) + off の計算を確認
    • class 0 (128B) × block 8 = 1024 bytes offset

Debug Strategy:

  1. PTR_TRACEマクロをTLS-SLL GUARDの前後に配置
  2. splice_trav関数のアセンブリ出力を確認
  3. TLS-SLL GUARDの条件判定を緩和して詳細ログ取得

Code Location to Fix:

  • core/box/tls_sll_box.h - splice_trav implementation
  • SPLICE_TO_SLL直後のTLS-SLL操作フロー

6. Verification Steps

After Fix:

  1. Same test should show proper alignment
  2. TLS-SLL GUARD should not fire
  3. PTR_TRACE should show tls_push/tls_pop operations
  4. SIGSEGV should be resolved

Test Commands:

HAKMEM_DEBUG_SEGV=1 HAKMEM_PTR_TRACE_DUMP=1 HAKMEM_FREE_WRAP_TRACE=1 ./out/debug/bench_fixed_size_hakmem 200000 1024 128

7. Summary

Root Cause: TLS-SLL splice_trav operation has critical pointer calculation error Location: SPLICE_TO_SLL immediate aftermath Impact: Misaligned memory access causes SIGSEGV Fix Priority: CRITICAL - core memory corruption issue

The TLS-SLL GUARD successfully identified the exact location of the problem!