This post is about situation where comments in BUG reports are
really valuable in term of learning and getting some internal
view of going process.
Let’s take a look at -> http://bugs.mysql.com/bug.php?id=80183
The report is about how you can not drop general tablespace if it was a crash of MySQL instant while running alter statement.
mysql> create tablespace ts1 add datafile '/var/lib/mysql_tablespaces/ts1.ibd' engine=innodb;
Query OK, 0 rows affected (0,02 sec)
Kill -9 process while altering: