Mysql replication, error 13 (permission denied) with slave_load_tmpdir
Assuming that the MySQL user is called "mysql" (check for "user" in my.cnf):


chown mysql.mysql -R /var/slavetmp
Edit /etc/apparmor.d/usr.sbin.mysqld.  Copy the lines for /var/lib/mysql and edit the copied lines to refer to /var/slavetmp
Restart AppArmor:  /etc/init.d/apparmor restart
Restart the mysql service