RHEL Engineering is moving the tracking of its product development work on RHEL 6 through RHEL 9 to Red Hat Jira (issues.redhat.com). If you're a Red Hat customer, please continue to file support cases via the Red Hat customer portal. If you're not, please head to the "RHEL project" in Red Hat Jira and file new tickets here. Individual Bugzilla bugs in the statuses "NEW", "ASSIGNED", and "POST" are being migrated throughout September 2023. Bugs of Red Hat partners with an assigned Engineering Partner Manager (EPM) are migrated in late September as per pre-agreed dates. Bugs against components "kernel", "kernel-rt", and "kpatch" are only migrated if still in "NEW" or "ASSIGNED". If you cannot log in to RH Jira, please consult article #7032570. That failing, please send an e-mail to the RH Jira admins at rh-issues@redhat.com to troubleshoot your issue as a user management inquiry. The email creates a ServiceNow ticket with Red Hat. Individual Bugzilla bugs that are migrated will be moved to status "CLOSED", resolution "MIGRATED", and set with "MigratedToJIRA" in "Keywords". The link to the successor Jira issue will be found under "Links", have a little "two-footprint" icon next to it, and direct you to the "RHEL project" in Red Hat Jira (issue links are of type "https://issues.redhat.com/browse/RHEL-XXXX", where "X" is a digit). This same link will be available in a blue banner at the top of the page informing you that that bug has been migrated.
Bug 813227 - Balloon value reported doesn't get updated after guest driver is removed and re-inserted.
Summary: Balloon value reported doesn't get updated after guest driver is removed and ...
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: kernel
Version: 6.3
Hardware: Unspecified
OS: Unspecified
medium
medium
Target Milestone: rc
: ---
Assignee: Amit Shah
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On:
Blocks:
TreeView+ depends on / blocked
 
Reported: 2012-04-17 09:27 UTC by Qunfang Zhang
Modified: 2015-09-28 02:09 UTC (History)
11 users (show)

Fixed In Version: kernel-2.6.32-288.el6
Doc Type: Bug Fix
Doc Text:
Clone Of:
Environment:
Last Closed: 2013-02-21 06:08:05 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHSA-2013:0496 0 normal SHIPPED_LIVE Important: Red Hat Enterprise Linux 6 kernel update 2013-02-20 21:40:54 UTC

Description Qunfang Zhang 2012-04-17 09:27:33 UTC 
Description of problem:
Boot a guest with virtio balloon devices -> Then balloon mem from the default max value to a smaller one, for example from 2048m to 2000m -> Next remove balloon driver from inside guest with rmmod command -> check the balloon value and enlarge it back to 2048M (it will not work as the driver is removed) -> reload the balloon driver from guest with modprobe command -> check the balloon value and enlarge it to 2048M. 

Result: failed, the mem is still 2000m.

Version-Release number of selected component (if applicable):
Host:
kernel-2.6.32-262.el6.x86_64
qemu-kvm-0.12.1.2-2.275.el6.x86_64
seabios-0.6.1.2-18.el6.x86_64
Guest:
kernel-2.6.32-262.el6.x86_64

How reproducible:
100%

Steps to Reproduce:
1. Boot a guest with virtio balloon device.
/usr/libexec/qemu-kvm -M rhel6.3.0 -cpu Conroe -enable-kvm -m 2G -smp 2,sockets=1,cores=2,threads=1 -name rhel6.3 -uuid 4c84db67-faf8-4498-9829-19a3d6431d9d -rtc base=localtime,driftfix=slew -netdev tap,id=hostnet0,vhost=on,script=/etc/qemu-ifup -device virtio-net-pci,netdev=hostnet0,id=net0,mac=00:1a:2a:42:10:62,bus=pci.0,addr=0x3 -boot c -spice port=5930,disable-ticketing -vga qxl -global qxl-vga.vram_size=33554432 -qmp tcp:0:4444,server,nowait -bios /usr/share/seabios/bios-pm.bin  -chardev socket,path=/tmp/qzhang-test-lucky,server,nowait,id=isa1 -device isa-serial,chardev=isa1,id=isa-serial1  -drive file=/dev/vgtest-qzhang/lv-6.3,if=none,format=qcow2,id=scsi0 -device virtio-scsi-pci,id=scsi0 -device scsi-disk,bus=scsi0.0,drive=scsi0,scsi-id=0,lun=0 -drive if=none,id=cd -device scsi-cd,drive=cd -usb -device usb-tablet,id=input0  -monitor stdio -device virtio-balloon-pci,id=balloon0,bus=pci.0


2. (qemu) info balloon
balloon: actual=2048

3. (qemu) balloon 2000
(qemu)info balloon
balloon: actual=2000

4. Inside guest:
#rmmod virtio-balloon

5. (qemu)info balloon 
balloon: actual=2000

6. (qemu) balloon 2048
(qemu)info balloon
balloon: actual=2000

7. Inside guest:
#modprobe virtio-balloon

8. (qemu)info balloon 
balloon: actual=2000

9. (qemu) balloon 2048
(qemu) info balloon
balloon: actual=2000
  
Actual results:
After step 9, the balloon value is 2000 (M)

Expected results:
After step 9, the balloon value should be 2048 (M)

Additional info:
If skip step 6, everything works well.
If after step 9, do:
10. (qemu) balloon 2040
then (qemu) balloon 2048
everything works well.
Comment 2 Amit Shah 2012-04-17 09:56:16 UTC 
What does the output of 'free' show within the guest after all these commands?

This could be a reporting issue rather than an actual bug in mem resizing.
Comment 3 Qunfang Zhang 2012-04-17 10:11:08 UTC 
Oh, I just want to update some information related 'free' output:

1. Step 2:
[root@localhost ~]# free -m
             total       used       free     shared    buffers     cached
Mem:          1878        467       1410          0         16        143
-/+ buffers/cache:        308       1570
Swap:         2015          0       2015

2. step 3:
[root@localhost ~]# free -m
             total       used       free     shared    buffers     cached
Mem:          1830        467       1363          0         16        143
-/+ buffers/cache:        307       1523
Swap:         2015          0       2015


2.From step 4-9, "free -m" always show the largest value as setting in the
command line.
That's the same output as when I just boot up guest and do nothing:

[root@localhost ~]# free -m
             total       used       free     shared    buffers     cached
Mem:          1878        467       1410          0         16        143
-/+ buffers/cache:        308       1570
Swap:         2015          0       2015
Comment 4 Amit Shah 2012-04-17 11:09:33 UTC 
OK, so this is as expected and the guest behaves normally.  If you try 'balloon 2000' as step 10, guest should update with new values.

This is a reporting problem, though.  No idea why qemu isn't querying the guest as to what the current balloon value is.
Comment 5 Ademar Reis 2012-04-17 15:42:25 UTC 
This is a corner case and the guest behaves correctly, so not critical, deferring to 6.4.
Comment 6 Luiz Capitulino 2012-04-26 17:59:39 UTC 
Doesn't seem to be a serious issue to me either. Will look into this soon to confirm it.
Comment 7 Amit Shah 2012-04-26 19:17:43 UTC 
Turns out the kernel doesn't update stats on module removal.  Patches posted upstream.
Comment 8 RHEL Program Management 2012-07-09 21:50:27 UTC 
This request was evaluated by Red Hat Product Management for
inclusion in a Red Hat Enterprise Linux release.  Product
Management has requested further review of this request by
Red Hat Engineering, for potential inclusion in a Red Hat
Enterprise Linux release for currently deployed products.
This request is not yet committed for inclusion in a release.
Comment 9 Jarod Wilson 2012-07-23 17:31:08 UTC 
Patch(es) available on kernel-2.6.32-288.el6
Comment 12 mazhang 2012-12-17 09:44:56 UTC 
Reproduce this bug on
host
kernel:2.6.32-279.9.1.el6.x86_64
qemu-kvm:qemu-kvm-0.12.1.2-2.265.el6.x86_64

guest
kernel:2.6.32-279.el6.x86_64

Steps to Reproduce:
1. Boot a guest with virtio balloon device.
/usr/libexec/qemu-kvm -M rhel6.3.0 -cpu host -enable-kvm -m 2G -smp 2,sockets=1,cores=2,threads=1 -name rhel6.3 -uuid 4c84db67-faf8-4498-9829-19a3d6431d9d -rtc base=localtime,driftfix=slew -boot c -spice port=5930,disable-ticketing -vga qxl -global qxl-vga.vram_size=33554432 -qmp tcp:0:4444,server,nowait -bios /usr/share/seabios/bios-pm.bin  -chardev socket,path=/tmp/qzhang-test-lucky,server,nowait,id=isa1 -device isa-serial,chardev=isa1,id=isa-serial1  -drive file=/root/RHEL-Server-6.3-64-virtio.qcow2,if=none,format=qcow2,id=scsi0 -device virtio-scsi-pci,id=scsi0 -device scsi-disk,bus=scsi0.0,drive=scsi0,scsi-id=0,lun=0 -drive if=none,id=cd -device scsi-cd,drive=cd -usb -device usb-tablet,id=input0  -monitor stdio -device virtio-balloon-pci,id=balloon0,bus=pci.0

2. (qemu) info balloon
balloon: actual=2048

3. (qemu) balloon 2000
(qemu)info balloon
balloon: actual=2000

4. Inside guest:
#rmmod virtio-balloon

5. (qemu)info balloon 
balloon: actual=2000

6. (qemu) balloon 2048
(qemu)info balloon
balloon: actual=2000

7. Inside guest:
#modprobe virtio-balloon

8. (qemu)info balloon 
balloon: actual=2000

9. (qemu) balloon 2048
(qemu) info balloon
balloon: actual=2000

Actual results:
After step 9, the balloon value is 2000 (M)

Expected results:
After step 9, the balloon value should be 2048 (M)


Verified this bug on
host
kernel:2.6.32-279.9.1.el6.x86_64
qemu-kvm:qemu-kvm-0.12.1.2-2.265.el6.x86_64

guest
kernel:2.6.32-347.el6.x86_64

Steps to Reproduce:
1. Boot a guest with virtio balloon device.
/usr/libexec/qemu-kvm -M rhel6.3.0 -cpu host -enable-kvm -m 2G -smp 2,sockets=1,cores=2,threads=1 -name rhel6.3 -uuid 4c84db67-faf8-4498-9829-19a3d6431d9d -rtc base=localtime,driftfix=slew -boot c -spice port=5930,disable-ticketing -vga qxl -global qxl-vga.vram_size=33554432 -qmp tcp:0:4444,server,nowait -bios /usr/share/seabios/bios-pm.bin  -chardev socket,path=/tmp/qzhang-test-lucky,server,nowait,id=isa1 -device isa-serial,chardev=isa1,id=isa-serial1  -drive file=/root/RHEL-Server-6.3-64-virtio.qcow2,if=none,format=qcow2,id=scsi0 -device virtio-scsi-pci,id=scsi0 -device scsi-disk,bus=scsi0.0,drive=scsi0,scsi-id=0,lun=0 -drive if=none,id=cd -device scsi-cd,drive=cd -usb -device usb-tablet,id=input0  -monitor stdio -device virtio-balloon-pci,id=balloon0,bus=pci.0

2. (qemu) info balloon
balloon: actual=2048

3. (qemu) balloon 2000
(qemu)info balloon
balloon: actual=2000


4. Inside guest:
#rmmod virtio-balloon

5. (qemu)info balloon 
balloon: actual=2048  --->the balloon value and enlarge it back to 2048M

6. (qemu) balloon 2048
(qemu)info balloon
balloon: actual=2048  

7. Inside guest:
#modprobe virtio-balloon

8. (qemu)info balloon 
balloon: actual=2048

9. (qemu) balloon 2048
(qemu) info balloon
balloon: actual=2048

Actual results:
After step 5 and 9, the balloon value is 2048 (M)
guest work well.

So this bug has been fixed.
Comment 13 juzhang 2012-12-18 03:21:55 UTC 
According to comment12, set this issue as verified.
Comment 15 errata-xmlrpc 2013-02-21 06:08:05 UTC 
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-2013-0496.html
Note You need to log in before you can comment on or make changes to this bug.