[hostinglimits:error] [pid 721956:tid 140505843804096] (28)No space left on device: mod_hostinglimits: Failed to create shared memory segment on file /var/logs/hostinglimits_shm.72195

It can be semaphores issue:
Cloudlinux kernel version: 2.6.32-673.26.1.lve1.4.15.el6.x86_64

ipcs -a
0x21019e52 145919280 root 600 78000 0
0xf8012979 325291313 root 600 78000 0
0xb0015185 648809778 root 600 78000 0
0x30015b4f 814452019 root 600 78000 0
0x47013071 983207220 root 600 78000 0
0x6901c6db 1153043765 root 600 78000 0
0x2f01e427 1323306294 root 600 78000 0
0xa8015f7b 1630965047 root 600 78000 0
0xd1017f3b 1800768824 root 600 78000 0
0x77019e6e 1960643897 root 600 78000 0
0xe901511c 2095910202 root 600 78000 0
0xd7014bdf 96374075 root 600 78000 0
0x8f014c0d 630754620 root 600 78000 0
0xa501e826 1071942973 root 600 78000 0
…
My advice to reboot the server, check uptime before reboot.