MySQL general log as table -- Scheduling cleaning
It won't cause problems, but you will lose all the old log entries, so advice above is good.

You can do a backup of logs if you want with:

mysqldump -p --lock_tables=false mysql general_log > genlog.sql

Do you need to have the general log on all the time? I usually only turn it on when I'm troubleshooting performance issues. MySQL logs EVERYTHING there (client connects, disconnects, and EVERY statement). In most systems, the logs get very big very quickly. There is also some performance overhead for this.