LP:1008293 - SET key_cache_segments leads to crashes in get_partitioned_key_cache_statistics, or safe_mutex_lock, or partitioned_key_cache_statistics

On 3 of the 4 servers i tried to do a "set global key_cache_segments = 8", 3 have crashed and only one didnt.

The crashing servers were :

• One on MariaDB 5.3.7 (immediate crash with "server has gone away" when sending the set command)
• One on MariaDB 5.5.23 (set command returns "OK" but server crashes just after that)
• One on MariaDB 5.5.24 (same as on the previous one)
  The server that has not crashed was on 5.5.23.

All the servers are on Debian Squeeze amd64 using MariaDB repository packages.

All servers have different datas and workloads (and are not using replication), these are used on a shared hosting environement so there is many databases/tables on each with many random accesses on them.

Did put the value on my.cnf and restarted completely the servers and it didnt crash (some have been up for weeks without a crash), so it seems to be only crashing when changing the parameter on a live server.

(attached two crash reports: 5.5.24 and 5.3.7)