mysqld got signal 11 触发bug

01:00:00 UTC - mysqld got signal 11 ;
This could be because you hit a bug. It is also possible that this binary
or one of the libraries it was linked against is corrupt, improperly built,
or misconfigured. This error can also be caused by malfunctioning hardware.
Attempting to collect some information that could help diagnose the problem.
As this is a crash and something is definitely wrong, the information
collection process might fail.

key_buffer_size=8388608
read_buffer_size=16777216
max_used_connections=318
max_threads=400
thread_count=295
connection_count=291
It is possible that mysqld could use up to 
key_buffer_size + (read_buffer_size + sort_buffer_size)*max_threads = 9878740 K  bytes of memory
Hope that's ok; if not, decrease some variables in the equation.

mysql突然挂掉，error日志显示内存资源耗尽，但是查看监控发现主机内存并没有出现匮乏的情况，报错中有一条select语句，是一个四重的子查询，经过在从库上验证，库也挂了， mysql子查询触发bug，导致库挂。

参考文章：

故障分析 | 一条 SELECT 语句跑崩了 MySQL ，怎么回事？ - 知乎