mysqldump of information_schema creates huge file

Hello

Percona-Server-server-55-5.5.33-rel31.1.566.rhel6.x86_64
RedHat Enterprise Linux Server release 6.4 (Santiago)

nearly no data in the DB, just mysql_installdb and a monitoring table.

tmpdir configured to:
tmpfs /mysqltmp tmpfs rw,gid=27,uid=27,size=10G,nr_inodes=10k,mode=0700 0 0

mysqldump --socket=/var/lib/mysql/mysql.sock --max_allowed_packet=1G --quick --single-transaction -u root -p$(cat /ruut/.mysql) information_schema > ttt.dmp

creates a
-rw-rw---- 1 mysql mysql 10094927872 Sep 20 15:52 #sql_2a5e_0.MYD
-rw-rw---- 1 mysql mysql 1024 Sep 20 15:52 #sql_2a5e_0.MYI

and crashes with:
mysqldump: Couldn't execute 'SELECT /*!40001 SQL_NO_CACHE */ /*!50084 SQL_NO_FCACHE */ * FROM `INNODB_BUFFER_PAGE`': Incorrect key file for table '/mysqltmp/#sql_2a5e_0.MYI'; try to repair it (126)

tmpdir on disk runs, because of more space:
-rw-rw---- 1 mysql mysql 17541113148 Sep 20 16:01 #sql_2e10_0.MYD
-rw-rw---- 1 mysql mysql 1024 Sep 20 16:01 #sql_2e10_0.MYI

but why is such a huge temptable created here (about 16GB) for dumping informationschema
the dump is 278Mb (other databases (versions) generate 900kb)

Is this "normal"?
What paramter may influence the size of the dump?
All scripts that loop over all databases could generate a problem here if tmpdir is not big enough.