RSS regression: v3.1.5 → v3.3.0 shows +81% VmRSS on musl/Alpine (26 MB → 47 MB)

**Summary**
Upgrading from mimalloc v3.1.5 to v3.3.0 (or v3.3.1) causes an ~81% increase in resident set size for a long-running Rust async service on Alpine/musl, with no application code changes.

**Environment**
OS: Alpine 3.21 (musl libc), aarch64-unknown-linux-musl static build
Compiler: Rust 1.94.1 via cc crate (musl-gcc)
Build flags: LTO (fat), codegen-units = 1, panic = abort
Runtime: tokio (8 worker threads), long-running HTTP + MQTT service
Observed on: Linux/Kubernetes (Docker), macOS/Podman (Apple Virtualization, ARM64)

**Measurements**
Idle RSS after startup + health-check warmup, read from /proc//status (VmRSS):

| mimalloc C version | Rust crate | VmRSS |
|---|---|---|
| v3.1.5 | 0.1.48 + features=["v3"] | 26 MB |
| v3.3.0 | 0.1.49 | 45 MB |
| v3.3.1 (latest) | 0.1.50 | 47 MB |
| v2.2.2 (default in 0.1.48) | 0.1.48 (no v3 feature) | 54 MB |

All builds from the same application source, same compiler, same flags — only the mimalloc version differs.

**Reproduction**

1. Build the same Rust binary twice: once linking mimalloc v3.1.5, once linking v3.3.1
2. Run both on Alpine/musl (aarch64 or x86_64)
3. Compare VmRSS after a few seconds of idle + health-check traffic

**Workaround**
Pinned to mimalloc crate 0.1.48 with features = ["v3"] (→ C v3.1.5).

**Possibly related**
#1104 — arena lock contention / page-map overhead in dev3+
#1014 — memory regression reported by Bun
#1025 — excessive memory retention

Start by reproducing the reported comparison between mimalloc v3.1.5 and v3.3.1 using the same Rust binary on Alpine/musl, then compare VmRSS after the stated warmup. Review the changes between those mimalloc versions and the related issues #1104, #1014, and #1025. Done means identifying and addressing the regression, with measurements showing the result on the reported environments.

Written by the indexing model from the issue text.