What happened to mysql, who will tell?

Question

linux

Here is the last excerpt from mysqld.log
After that, mysql lay down.

150702 02:29:55 mysqld_safe Number of processes running now: 0
150702 02:29:55 mysqld_safe mysqld restarted
150702  2:29:55 [Warning] Using unique option prefix key_buffer instead of key_buffer_size is deprecated and will be removed in a future release. Please use the full name instead.
150702  2:29:56 [Note] Plugin 'FEDERATED' is disabled.
150702  2:29:56 InnoDB: The InnoDB memory heap is disabled
150702  2:29:56 InnoDB: Mutexes and rw_locks use GCC atomic builtins
150702  2:29:56 InnoDB: Compressed tables use zlib 1.2.3
150702  2:29:56 InnoDB: Using Linux native AIO
150702  2:29:56 InnoDB: Initializing buffer pool, size = 128.0M
InnoDB: mmap(135987200 bytes) failed; errno 12
150702  2:29:56 InnoDB: Completed initialization of buffer pool
150702  2:29:56 InnoDB: Fatal error: cannot allocate memory for the buffer pool
150702  2:29:56 [ERROR] Plugin 'InnoDB' init function returned error.
150702  2:29:56 [ERROR] Plugin 'InnoDB' registration as a STORAGE ENGINE failed.
150702  2:29:56 [ERROR] Unknown/unsupported storage engine: InnoDB
150702  2:29:56 [ERROR] Aborting

150702  2:29:56 [Note] /usr/libexec/mysqld: Shutdown complete

150702 02:29:56 mysqld_safe mysqld from pid file /var/run/mysqld/mysqld.pid ended

Where to dig? Is there not enough memory? There is one wordpress without traffic for 512mb ram.

Answer 1

# nano /etc/my.cnf
[mysqld]
innodb_buffer_pool_size = 10M
# service mysqld restart