Bug 606953

Summary:	fork causes trouble for vcpu threads
Product:	Red Hat Enterprise Linux 5	Reporter:	Glauber Costa <gcosta>
Component:	kvm	Assignee:	Virtualization Maintenance <virt-maint>
Status:	CLOSED ERRATA	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	medium	Docs Contact:
Priority:	high
Version:	5.5	CC:	armbru, ehabkost, gcosta, kcao, kraxel, llim, mkenneth, tburke, virt-maint, ykaul
Target Milestone:	rc	Keywords:	ZStream
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:	kvm-83-186.el5	Doc Type:	Bug Fix
Doc Text:	In the kvm kernel module, some internal KVM memory slots were incorrectly being handled by copy-on-write after a fork() function call, which caused issues when qemu-kvm ran child processes. This update fixes the handling of internal KVM memory slots on fork() to avoid those issues.	Story Points:	---
Clone Of:	601192	Environment:
Last Closed:	2011-01-13 23:36:34 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:
Embargoed:
Bug Depends On:	601192
Bug Blocks:	580949, 610341

Comment 7 Douglas Silas 2010-07-28 15:39:58 UTC

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:
In the kvm kernel module, some internal KVM memory slots were incorrectly being handled by copy-on-write after a fork() function call, which caused issues when qemu-kvm ran child processes. This update fixes the handling of internal KVM memory slots on fork() to avoid those issues.

Comment 9 Cao, Chen 2010-11-11 10:13:58 UTC

verified on
# rpm -q kvm
kvm-83-207.el5


boot guest with:
/usr/libexec/qemu-kvm -name 'vm1' -monitor stdio -drive file='/home/autotest-devel/client/tests/kvm/images/win2008-64-virtio.qcow2',index=0,if=virtio,media=disk,cache=none,boot=on,format=qcow2 -net nic,vlan=0,model=virtio,macaddr='9a:30:70:9c:34:b4' -net tap,vlan=0,ifname='virtio_xxx_5900',script='/home/autotest-devel/client/tests/kvm/scripts/qemu-ifup-switch',downscript='no' -m 2048 -smp 2 -soundhw ac97 -vnc :0  -rtc-td-hack -M rhel5.6.0 -usbdevice tablet

migrate with:
migrate "exec:gzip -c > /home/mig-xxxx1"

boot the dst guest with:
/usr/libexec/qemu-kvm -name 'vm1' -monitor stdio -drive file='/home/autotest-devel/client/tests/kvm/images/win2008-64-virtio.qcow2',index=0,if=virtio,media=disk,cache=none,boot=on,format=qcow2 -net nic,vlan=0,model=virtio,macaddr='9a:30:70:9c:34:b4' -net tap,vlan=0,ifname='virtio_xxx_5900',script='/home/autotest-devel/client/tests/kvm/scripts/qemu-ifup-switch',downscript='no' -m 2048 -smp 2 -soundhw ac97 -vnc :0  -rtc-td-hack -M rhel5.6.0 -usbdevice tablet -incoming "exec:gzip -c -d /home/xxxmig"


migration finished good, guest is good, too

Comment 12 errata-xmlrpc 2011-01-13 23:36:34 UTC

An advisory has been issued which should help the problem
described in this bug report. This report is therefore being
closed with a resolution of ERRATA. For more information
on therefore solution and/or where to find the updated files,
please follow the link below. You may reopen this bug report
if the solution does not work for you.

http://rhn.redhat.com/errata/RHSA-2011-0028.html