When your article have some unlegal characters, the search function will not work.
See the https://segmentfault.com/q/1010000013084615 discussion for more details.
To debug, go to the url to see which blog rise this issue. http://localhost:4000/search.xml
(通过注释并且在本地调试，发现是kernels trick这个文件有问题。)
Solution
应该是有非法字符，local search无法加载出来非utf-8编码的字符。通过注释排除法，找到问题根源。