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Bug 592033 - race condition in pvclock wallclock calculation
Summary: race condition in pvclock wallclock calculation
Alias: None
Product: Red Hat Enterprise Linux 6
Classification: Red Hat
Component: kernel
Version: 6.0
Hardware: All
OS: Linux
Target Milestone: rc
: ---
Assignee: Glauber Costa
QA Contact: Virtualization Bugs
Depends On: 592021
Blocks: Rhel5KvmTier2
TreeView+ depends on / blocked
Reported: 2010-05-13 18:01 UTC by Glauber Costa
Modified: 2013-01-09 22:34 UTC (History)
5 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of: 592021
Last Closed: 2010-11-11 16:11:27 UTC
Target Upstream Version:

Attachments (Terms of Use)

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 Product and 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

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
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

There is no huge time drift happens on each guest.

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

Comment 6 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.

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