Symptoms
Command:
aptitude install php7.0-fpm
Response:
Job for php7.0-fpm.service failed. See ‘systemctl status php7.0-fpm.service’ and ‘journalctl -xn’ for details.
Command:
journalctl -xn
Response:
Fatal Error Unable to allocate shared memory segment of 67108864 bytes: mmap: Cannot allocate memory (12)
Cause
The standard OPcache PHP module is unable to allocate shared memory segment because the opcache.memory_consumption option value is bigger than maximum allowed segment size on the server.
Command:
ipcs -lm
Response:
------ Shared Memory Limits --------
max number of segments = 4096
max seg size (kbytes) = 32768
max total shared memory (kbytes) = 8388608
min seg size (bytes) = 1
Command:
php -i | grep opcache.memory_consumption
Response:
opcache.memory_consumption => 64 => 64
Solution
Edit /etc/sysctl.conf:
kernel.shmmax=200000000
kernel.shmall=50000
Then reboot and test.