MySQL Crashed with Fatal error cannot allocate memory for the buffer pool

There are two reasons for this error “cannot allocate memory for the buffer pool”
1) The system has no enough RAM or SWAP
2) innodb_buffer_pool_size is bigger.

To fix this problem you can try two things

1) Add swap memory.

2) Edit /etc/my.cnf, and add the following line under the [mysqld] heading.
[mysqld]

innodb_buffer_pool_size=64M

Now you can shutdown mysql server and start it again

mysqladmin -uroot -p shutdown

service mysqld start