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f6b06a0311
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Fix: Active counter double-decrement in P0 batch refill (4T crash → stable)
## Problem
HAKMEM 4T crashed with "free(): invalid pointer" on startup:
- System/mimalloc: 3.3M ops/s ✅
- HAKMEM 1T: 838K ops/s (-75%) ⚠️
- HAKMEM 4T: Crash (Exit 134) ❌
Error: superslab_refill returned NULL (OOM), active=0, bitmap=0x00000000
## Root Cause (Ultrathink Task Agent Investigation)
Active counter double-decrement when re-allocating from freelist:
1. Free → counter-- ✅
2. Remote drain → add to freelist (no counter change) ✅
3. P0 batch refill → move to TLS cache (forgot counter++) ❌ BUG!
4. Next free → counter-- ❌ Double decrement!
Result: Counter underflow → SuperSlab appears "full" → OOM → crash
## Fix (1 line)
File: core/hakmem_tiny_refill_p0.inc.h:103
+ss_active_add(tls->ss, from_freelist);
Reason: Freelist re-allocation moves block from "free" to "allocated" state,
so active counter MUST increment.
## Verification
| Setting | Before | After | Result |
|----------------|---------|----------------|--------------|
| 4T default | ❌ Crash | ✅ 838,445 ops/s | 🎉 Stable |
| Stability (2x) | - | ✅ Same score | Reproducible |
## Remaining Issue
❌ HAKMEM_TINY_REFILL_COUNT_HOT=64 triggers crash (class=4 OOM)
- Suspected: TLS cache over-accumulation or memory leak
- Next: Investigate HAKMEM_TINY_FAST_CAP interaction
🤖 Generated with [Claude Code](https://claude.com/claude-code)
Co-Authored-By: Claude <noreply@anthropic.com>
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2025-11-07 12:37:23 +09:00 |
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