I'm running libvirt across a fleet of CentOS 7 desktops to provide VMs for other operating systems, and they've been running fine for the last year, through rebuilds, etc.

In the last week, PCs that have been rebuilt no longer start our VMs, failing with the error:

error: internal error: process exited while connecting to monitor: 2016-09-15T10:15:12.839724Z qemu-kvm: -chardev pty,id=charserial0: Failed to create chardev

Various sites list remounting /dev/pts to solve this, with the command:

mount -n -t devpts -o remount,mode=0620,gid=5 devpts /dev/pts

After this command, the mount entry for devpts changed:

devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,seclabel,gid=5,mode=620,ptmxmode=000)
devpts on /dev/pts type devpts (rw,relatime,seclabel,gid=5,mode=620,ptmxmode=000)

However, the chardev error is still present.

The VM log in /var/log/libvirt/qemu shows:

2016-09-15 10:15:59.422+0000: starting up libvirt version: 1.2.17, package: 13.el7_2.5 (CentOS BuildSystem <http://bugs.centos.org>, 2016-06-23-14:23:27, worker1.bsys.centos.org), qemu version: 1.5.3 (qemu-kvm-1.5.3-105.el7_2.7)
LC_ALL=C PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin QEMU_AUDIO_DRV=none /usr/libexec/qemu-kvm -name centos6 -S -machine pc-i440fx-rhel7.0.0,accel=kvm,usb=off -m 16384 -realtime mlock=off -smp 4,sockets=4,cores=1,threads=1 -uuid 901c9deb-1935-4cfe-b9b4-ea2221d10487 -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-centos6/monitor.sock,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot menu=on,strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/srv/vm/centos6-vda.qcow2,if=none,id=drive-virtio-disk0,format=raw,cache=none,aio=native -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=2 -netdev tap,fd=23,id=hostnet0 -device e1000,netdev=hostnet0,id=net0,mac=52:54:00:02:59:93,bus=pci.0,addr=0x3,bootindex=1 -chardev pty,id=charserial0 -device isa-serial,chardev=charserial0,id=serial0 -vnc -vga cirrus -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5 -msg timestamp=on
2016-09-15T10:15:59.508359Z qemu-kvm: -chardev pty,id=charserial0: Failed to create chardev
2016-09-15 10:15:59.682+0000: shutting down

Anyone got any ideas? The only configuration change we have introduced in the last few weeks is creating local user accounts and turning off NIS on those boxes. SELinux is set to Permissive.


Iain Hallam.