Bug 592033

Summary:	race condition in pvclock wallclock calculation
Product:	Red Hat Enterprise Linux 6	Reporter:	Glauber Costa <gcosta>
Component:	kernel	Assignee:	Glauber Costa <gcosta>
Status:	CLOSED CURRENTRELEASE	QA Contact:	Virtualization Bugs <virt-bugs>
Severity:	medium	Docs Contact:
Priority:	low
Version:	6.0	CC:	qcai, szhou, tburke, virt-maint, ykaul
Target Milestone:	rc
Target Release:	---
Hardware:	All
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:	592021	Environment:
Last Closed:	2010-11-11 16:11:27 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:	592021
Bug Blocks:	533943, 580948

Description Glauber Costa 2010-05-13 18:01:39 UTC

+++ This bug was initially created as a clone of Bug #592021 +++

The hypervisor code for wallclock setting in pvclock is subject to race, since the version variable is static, and thus, shared among all guests.

This means that theoretically, one guest can mess up with the others view of version, causing it to be different among reads, which can lead to a livelock.

Comment 1 RHEL Program Management 2010-05-13 19:06:40 UTC

This request was evaluated by Red Hat Product Management for inclusion in a Red
Hat Enterprise Linux major release.  Product Management has requested further
review of this request by Red Hat Engineering, for potential inclusion in a Red
Hat Enterprise Linux Major release.  This request is not yet committed for
inclusion.

Comment 2 Aristeu Rozanski 2010-05-28 20:37:41 UTC

Patch(es) available on kernel-2.6.32-31.el6

Comment 5 Shirley Zhou 2010-08-17 07:37:01 UTC

Verify this bug with kernel-2.6.32-63.el6 as following:

1. sync time on host
ntpdate -b clock.redhat.com
2. Run 4 rhel6 guest on host with option
 -no-kvm-pit-reinjection   -rtc base=utc,clock=host,driftfix=slew
3.check time info  on each guest
ntpdate -q clock.redhat.com

There is no huge time drift happens on each guest.

So I think this bug has been fixed. change status to verified.

Comment 6 releng-rhel@redhat.com 2010-11-11 16:11:27 UTC

Red Hat Enterprise Linux 6.0 is now available and should resolve
the problem described in this bug report. This report is therefore being closed
with a resolution of CURRENTRELEASE. You may reopen this bug report if the
solution does not work for you.