I ran into this bug on both Percona 5.1.66 and Percona 5.1.67

From my testing I believe this bug happens when I have innodb_lazy_drop_table enabled and I issue a drop schema after the buffer pool is warmed up. I have been able to duplicate the bug twice by using pt-archiver to warm up buffer pool then issuing a drop database command. 

When I issue the drop schema command the instance freezes with the exception that you can still do a show process list but you cannot do anything else including read from MyISAM tables. The drop schema command sticks on checking permissions. 

| 16 | sanitized | sanitized:44918 | archive_sanitized | Query   |  529 | checking permissions | drop schema archive_sanitized

The only way I can get out of this frozen state is to shutdown mysql.  Then I have corrupted innodb table space and I am unable to clear the error the innodb recovery techniques outlined in manual.  The only way I am able to recover is to dump out my innodb tables and delete ibdata and ib_logfiles and re-import my data.  


Version: '5.1.66rel14.2-log'  socket: '/san/analytics/analytics.sock'  port: 3306  Percona Server with XtraDB (GPL), Release rel14.2, Revision 501
130208 22:00:56 InnoDB: Completed reading buffer pool pages (requested: 229486, read: 229474)
InnoDB: Warning: hash index ref_count (6467) is not zero after fil_discard_tablespace().
index: "PRIMARY" table: "archive_sanitized/sanitized_2004"
InnoDB: Warning: hash index ref_count (22975) is not zero after fil_discard_tablespace().
index: "PRIMARY" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 5 secs for hash index ref_count (161) to drop to 0.
index: "idx_sanitized_date_created" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 10 secs for hash index ref_count (161) to drop to 0.
index: "idx_sanitized_date_created" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 15 secs for hash index ref_count (161) to drop to 0.
index: "idx_sanitized_date_created" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 20 secs for hash index ref_count (161) to drop to 0.
index: "idx_sanitized_date_created" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 25 secs for hash index ref_count (161) to drop to 0.
index: "idx_sanitized_date_created" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 30 secs for hash index ref_count (161) to drop to 0.
index: "idx_sanitized_date_created" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 35 secs for hash index ref_count (161) to drop to 0.



Version: '5.1.67rel14.3-log'  socket: '/san/analytics/analytics.sock'  port: 3306  Percona Server with XtraDB (GPL), Release rel14.3, Revision 50
6
InnoDB: Warning: hash index ref_count (4715) is not zero after fil_discard_tablespace().
index: "PRIMARY" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 5 secs for hash index ref_count (4715) to drop to 0.
index: "PRIMARY" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 10 secs for hash index ref_count (4715) to drop to 0.
index: "PRIMARY" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 15 secs for hash index ref_count (4715) to drop to 0.
index: "PRIMARY" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 20 secs for hash index ref_count (4715) to drop to 0.
index: "PRIMARY" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 25 secs for hash index ref_count (4715) to drop to 0.
index: "PRIMARY" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 30 secs for hash index ref_count (4715) to drop to 0.
index: "PRIMARY" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 35 secs for hash index ref_count (4715) to drop to 0.
index: "PRIMARY" table: "archive_sanitized/sanitized_2004"
InnoDB: Error: Waited for 40 secs for hash index ref_count (4715) to drop to 0.