[Bug] corrupted size vs. prev_size in fastbins

### Checklist

- [x] 1. I have searched related issues but cannot get the expected help.
- [x] 2. The bug has not been fixed in the latest version.
- [x] 3. Please note that if the bug-related issue you submitted lacks corresponding environment info and a minimal reproducible demo, it will be challenging for us to reproduce and resolve the issue, reducing the likelihood of receiving feedback.

### Describe the bug

Run Qwen3.5 with turbomind engine.

After several time, lmdeploy crash with logs:

corrupted size vs. prev_size in fastbins
Aborted (core dumped)

### Reproduction

It is currently unknown.

### Environment

```Shell
-
```

### Error traceback

```Shell

```