I have writen a article in google doc to explain how to use reclaimable freelist:

https://docs.google.com/document/d/1zHv-c3ZgYJnYjX6Bt1FsBTdBswIK7YFCN3vcYGMpxZ4/edit?usp=sharing

Feel free to make changes and additions as necessary.
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Yunkai Zhang
Work at Taobao