I guess it's OK to remount /dev/shm, from my test:
$ df -h /dev/shm
Filesystem Size Used Avail Use% Mounted on
none 10G 144K 10G 1% /run/shm
$ sudo mount -o remount,size=11G /dev/shm
$ df -h /dev/shm
Filesystem Size Used Avail Use% Mounted on
none 11G 144K 11G 1% /run/shm
I guess mount follows the link. I will edit.