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Description of problem: virtio_cleanup() is supposed to reverse the mallocs in virtio_common_init(). However, it doesn't free up RAM allocated for device structures (VirtIOBlock, VirtIOBalloon, VirtIOSerial, VirtIONet) which embed the VirtIODevice struct. This means all the virtio devices leak memory on unplug or qemu exit.
Since there is also memory leak in virtio-blk and virtio-balloon which is fixed on qemu-kvm-0.12.1.2-2.179.el6, choose virtio-net to verify this bug. Steps to reproduce and verify: ------------------------------------ 1.Disable as more services as possible in level 3 and init 3: [root@localhost ~]# ls /etc/rc.d/rc3.d/ K01libvirt-guests K05atd K30postfix K50snmpd K74acpid K75quota_nld K83rpcidmapd K85messagebus K88iscsi K92ip6tables S05cgconfig K01smartd K10psacct K30spice-vdagentd K50snmptrapd K74haldaemon K75udev-post K84NetworkManager K86cgred K88rsyslog K92iptables S13rpcbind K02avahi-daemon K10saslauthd K46radvd K60crond K74ntpd K80kdump K84wpa_supplicant K87irqbalance K89iscsid K99cpuspeed S84ksm K02rhsmcertd K16abrtd K50dnsmasq K60nfs K75netfs K83nfslock K85ebtables K87restorecond K89rdisc K99lvm2-monitor S85ksmtuned K03rhnsd K25sshd K50netconsole K69rpcsvcgssd K75ntpdate K83rpcgssd K85mdmonitor K88auditd K90network K99sysstat S99local 2.Make sure top suggests there are not other memory consuming processes: PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND 1 root 20 0 19204 1492 1208 S 0.0 0.0 0:00.62 init 2 root 20 0 0 0 0 S 0.0 0.0 0:00.00 kthreadd 3 root RT 0 0 0 0 S 0.0 0.0 0:00.01 migration/0 4 root 20 0 0 0 0 S 0.0 0.0 0:00.00 ksoftirqd/0 5 root RT 0 0 0 0 S 0.0 0.0 0:00.00 migration/0 3.Boot guest, do 300 times virtio-net-pci device hotplug/unplug, use "free -m" when: 1) before start qemu 2) before hotplug/unplug 3) after hotplug/unplug 4) after exit qemu each time before "free -m", do "echo 3 > /proc/sys/vm/drop_caches" first. Actual results: --------------------- reproduced on qemu-kvm-0.12.1.2-2.178.el6.x86_64: used free buffers/cached 183 7279 0/7 <---before start qemu 746 6716 0/9 <---start qemu 761 6701 0/9 <---after hotplug/unplug 300 times 183 7278 0/7 <---after exit qemu verified on qemu-kvm-0.12.1.2-2.184.el6.x86_64: used free buffers/cached 182 7279 0/6 <---before start qemu 753 6709 0/9 <---start qemu 758 6704 0/9 <---after hotplug/unplug 300 times 183 7279 0/6 <---after exit qemu Conclusion: --------------- After hotplug/unplug 300 times, but not exit yet, on qemu-kvm 178, system free memory reduces 15M, on 184, reduces only 5M, based on results above, the patch works well, verified.
Since the problem described in this bug report should be resolved in a recent advisory, it has been closed with a resolution of ERRATA. For information on the advisory, and where to find the updated files, follow the link below. If the solution does not work for you, open a new bug report. http://rhn.redhat.com/errata/RHSA-2011-1531.html