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Description of problem:
Boot a guest with virtio balloon device, and balloon the memory to a smaller one.
Then hot plug the second virtio balloon device, the memory value will be re-set to the original value as configured in the qemu command line. Then balloon the memory, it works well.
Version-Release number of selected component (if applicable):
kernel-2.6.32-171.el6.x86_64
qemu-kvm-0.12.1.2-2.171.el6.x86_64
How reproducible:
Always
Steps to Reproduce:
1.Boot guest with one virtio balloon device.
/usr/libexec/qemu-kvm -m 16G -smp 4 -cpu cpu64-rhel6,+x2apic -usbdevice tablet -drive file=win7-64-virtio.qcow2,format=qcow2,if=none,id=drive-ide0-0-0,werror=stop,rerror=stop,cache=none -device virtio-blk-pci,drive=drive-ide0-0-0,id=ide0-0-0 -netdev tap,id=hostnet0,script=/etc/qemu-ifup -device e1000,netdev=hostnet0,mac=00:10:1a:20:06:28,bus=pci.0,addr=0x6 -boot dc -uuid bea9c85e-0a47-4030-979d-5d94bb3d6161 -rtc-td-hack -no-kvm-pit-reinjection -monitor stdio -qmp tcp:0:4444,server,nowait -name win7-64-balloon -spice disable-ticketing,port=5931 -vga qxl -device virtio-balloon-pci,bus=pci.0,id=balloon0
2.Balloon the memory, it works.
{"execute":"query-balloon"}
{"return": {"actual": 17179869184}}
{"execute":"balloon","arguments":{"value":16106127360}}
{"return": {}}
{"execute":"query-balloon"}
{"return": {"actual": 16106127360}}
3.Hot plug another virtio balloon device.
{"execute":"device_add","arguments":{"driver":"virtio-balloon-pci","id":"balloon1"}}
{"return": {}}
4. Check the memory:
{"execute":"query-balloon"}
{"return": {"actual": 17179869184}}
5.
{"execute":"balloon","arguments":{"value":16106127360}}
{"return": {}}
{"execute":"query-balloon"}
{"return": {"actual": 16743661568}}
Actual results:
After step4, the memory value is re-set to the original max value.
Expected results:
After step4, the memory value should not change.
Additional info:
This is actually fixed by the fix for bug 725625. We now don't allow more than one active balloon device.
Since it's not really a duplicate of the other bug, I'll just put this ON_QA, and update the 'Fixed in version' field.
Verified this bug on qemu-kvm-0.12.1.2-2.209.el6.x86_64. It is not allowed to add more than one active balloon device currently. So will not hit this issue.
(qemu) device_add virtio-balloon-pci,id=balloon1
Another balloon device already registered
Device 'virtio-balloon-pci' could not be initialized
So, this issue is fixed. Setting to VERIFIED.
Technical note added. If any revisions are required, please edit the "Technical Notes" field
accordingly. All revisions will be proofread by the Engineering Content Services team.
New Contents:
No documentation necessary
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/RHBA-2012-0746.html
Description of problem: Boot a guest with virtio balloon device, and balloon the memory to a smaller one. Then hot plug the second virtio balloon device, the memory value will be re-set to the original value as configured in the qemu command line. Then balloon the memory, it works well. Version-Release number of selected component (if applicable): kernel-2.6.32-171.el6.x86_64 qemu-kvm-0.12.1.2-2.171.el6.x86_64 How reproducible: Always Steps to Reproduce: 1.Boot guest with one virtio balloon device. /usr/libexec/qemu-kvm -m 16G -smp 4 -cpu cpu64-rhel6,+x2apic -usbdevice tablet -drive file=win7-64-virtio.qcow2,format=qcow2,if=none,id=drive-ide0-0-0,werror=stop,rerror=stop,cache=none -device virtio-blk-pci,drive=drive-ide0-0-0,id=ide0-0-0 -netdev tap,id=hostnet0,script=/etc/qemu-ifup -device e1000,netdev=hostnet0,mac=00:10:1a:20:06:28,bus=pci.0,addr=0x6 -boot dc -uuid bea9c85e-0a47-4030-979d-5d94bb3d6161 -rtc-td-hack -no-kvm-pit-reinjection -monitor stdio -qmp tcp:0:4444,server,nowait -name win7-64-balloon -spice disable-ticketing,port=5931 -vga qxl -device virtio-balloon-pci,bus=pci.0,id=balloon0 2.Balloon the memory, it works. {"execute":"query-balloon"} {"return": {"actual": 17179869184}} {"execute":"balloon","arguments":{"value":16106127360}} {"return": {}} {"execute":"query-balloon"} {"return": {"actual": 16106127360}} 3.Hot plug another virtio balloon device. {"execute":"device_add","arguments":{"driver":"virtio-balloon-pci","id":"balloon1"}} {"return": {}} 4. Check the memory: {"execute":"query-balloon"} {"return": {"actual": 17179869184}} 5. {"execute":"balloon","arguments":{"value":16106127360}} {"return": {}} {"execute":"query-balloon"} {"return": {"actual": 16743661568}} Actual results: After step4, the memory value is re-set to the original max value. Expected results: After step4, the memory value should not change. Additional info: