Symptoms

• Every once in a while, randomly, KVM VPS running with SolusVM virtual machine is getting suspended or stopped.
• The following message can be found in dmesg or in /var/log/messages:

  Nov 2 13:54:33 server kvm: 25 guests now active
  server kernel: qemu-kvm invoked oom-killer: gfp_mask=0xd0, order=0, oom_score_adj=0
  server kernel: Task in /machine.slice/machine-qemu\x2d291\x2dkvm1309.scope killed as a result of limit of /machine.slice/machine-qemu\x2d291\x2dkvm1309.scope
  server kernel: memory: usage 9437184kB, limit 9437184kB, failcnt 155666
  server kernel: memory+swap: usage 9621056kB, limit 9007199254740988kB, failcnt 0
  server kernel: kmem: usage 0kB, limit 9007199254740988kB, failcnt 0
  server kernel: Memory cgroup stats for /machine.slice/machine-qemu\x2d291\x2dkvm1309.scope: cache:20KB rss:9437164KB rss_huge:0KB mapped_file:20KB swap:183872KB inactive_anon:1048736KB active_anon:8388452KB inactive_file:0KB active_file:0KB unevictable:0KB
  server kernel: Memory cgroup out of memory: Kill process 67178 (CPU 5/KVM) score 541 or sacrifice child

• The same issue might occur during installing of Windows 2016 guest from ISO image.

Cause

Insufficient value for hard_limits parameters in the configuration file of the virtual machine

Resolution

Increase hard_limit value using SolusVM tuning. The information below is also available on the following documentation page

1. Connect to the slave KVM server via SSH
2. Check if the /usr/local/solusvm/data/config.ini exist and create a copy of example configuration file if it is not:

   # cp -a /usr/local/solusvm/data/config.ini.example /usr/local/solusvm/data/config.ini

3. In this file /usr/local/solusvm/data/config.ini set domain_config_exclude_memtune as false:

   ;; Don’t write memtune settings to domains configuration file (true|false)
   domain_config_exclude_memtune = false

4. And tune domain_config_memtune_hard_limit_percent_memory parameter to required value:

   ;; If memtune hard_limit is used in the domains configuration file set

   domain_config_memtune_hard_limit_percent_memory = 110

   domain_config_memtune_soft_limit_percent_memory = 110

   domain_config_memtune_swap_hard_limit_percent_memory = 125

   for example 200 will set a doubled value from RAM value assigned to the virtual server

5. For newly created virtual servers limits will be applied automatically. To apply the changes for already existing virtual servers, reboot them.