After RAM upgrade, the system does not show correct memory amount

Issue

• New RAM is added to the system and 'dmidecode' shows total of 384GB, but 'free -m' does not show correct information

[root@localhost:~]# dmidecode 2.11 | grep Size | grep 32
        Installed Size: 320 kB
        Maximum Size: 320 kB
        Installed Size: 320 kB
        Maximum Size: 320 kB
        Installed Size: 320 kB
        Maximum Size: 320 kB
        Installed Size: 320 kB
        Maximum Size: 320 kB
        Maximum Size: 32768 kB
        Maximum Size: 32768 kB
        Maximum Size: 32768 kB
        Maximum Size: 32768 kB
        Size: 32 GB
        Size: 32 GB
        Size: 32 GB
        Size: 32 GB
        Size: 32 GB
        Size: 32 GB
        Size: 32 GB
        Size: 32 GB
        Size: 32 GB
        Size: 32 GB
        Size: 32 GB
        Size: 32 GB

• It only shows 252 GB of memory with 'free' command

[root@localhost:~]# free -m
             total       used       free     shared    buffers     cached
Mem:        258077       2325     255751          0        180       1390
-/+ buffers/cache:        755     257321
Swap:        61439          0      61439