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Bug 294811

Summary: kernel BUG at mm/rmap.c:590 during suspend/resume testing
Product: Red Hat Enterprise Linux 5 Reporter: Ian Campbell <ijc>
Component: kernel-xenAssignee: Chris Lalancette <clalance>
Status: CLOSED ERRATA QA Contact: Martin Jenner <mjenner>
Severity: low Docs Contact:
Priority: low    
Version: 5.0CC: jmadden, sputhenp, xen-maint
Target Milestone: ---   
Target Release: ---   
Hardware: All   
OS: Linux   
Whiteboard:
Fixed In Version: RHBA-2008-0314 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2008-05-21 14:55:27 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:    
Bug Blocks: 311431    
Attachments:
Description Flags
test case to reproduce issue
none
Patch to fix protnone problem during PV save/restore
none
xen-unstable 12402:ade94aa072c5 ported to 2.6.9-67.EL
none
xen-unstable 12545:50467f56ed65 ported to 2.6.9-67.EL
none
xen-unstable 13998:d2dff286994d ported to 2.6.9-67.EL
none
xen-unstable 12402:ade94aa072c5 ported to 2.6.18-53.el5
none
xen-unstable 12545:50467f56ed65 ported to 2.6.18-53.el5
none
xen-unstable 13998:d2dff286994d ported to 2.6.18-53.el5 none

Description Ian Campbell 2007-09-18 14:33:57 UTC 
The kernel needs to ensure that not-present PTEs contain a PFN and not an MFN.
This is because the suspend-resume code will not canonicalize not present PTEs
since they may contain values which are not PFN or MFNs.

This was observed with 2.6.18-8.1.10.el5 but I think it might apply to the
rhel4u5 Xen kernel as well.

The problem was solved upstream with
http://xenbits.xensource.com/xen-unstable.hg?rev/d2dff286994d
http://xenbits.xensource.com/kernels/rhel4x.hg?rev/4fd6832bb54f

Reproducible by running the attached main.c (gcc -O2 main.c) over a save restore
iteration.
Comment 1 Ian Campbell 2007-09-18 14:33:57 UTC 
Created attachment 198411 [details]
test case to reproduce issue
Comment 4 Chris Lalancette 2007-12-13 22:08:01 UTC 
Created attachment 288051 [details]
Patch to fix protnone problem during PV save/restore

OK, I was able to easily reproduce the problem, and come up with a backport. 
This backport is really a combination of 3 changesets from upstream
Xen-unstable:
12402, 13998, 14006.  It's a pretty straightforward backport; I only had to
remove one chunk (that removed a line we didn't have to begin with), and to
adjust line numbers appropriately.  Before the patch, running the test program
in a loop would end up in a reliable oops when doing a save/restore cycle on
the domain.  I'm still testing, but at least on i686 I've gone 20 save/restore
cycles already without oopsing.

Chris Lalancette
Comment 5 Ian Campbell 2007-12-14 09:06:09 UTC 
Created attachment 288751 [details]
xen-unstable 12402:ade94aa072c5 ported to 2.6.9-67.EL
Comment 6 Ian Campbell 2007-12-14 09:07:18 UTC 
Created attachment 288761 [details]
xen-unstable 12545:50467f56ed65 ported to 2.6.9-67.EL
Comment 7 Ian Campbell 2007-12-14 09:08:09 UTC 
Created attachment 288771 [details]
xen-unstable 13998:d2dff286994d ported to 2.6.9-67.EL
Comment 8 Ian Campbell 2007-12-14 09:09:35 UTC 
Created attachment 288781 [details]
xen-unstable 12402:ade94aa072c5 ported to 2.6.18-53.el5
Comment 9 Ian Campbell 2007-12-14 09:10:15 UTC 
Created attachment 288791 [details]
xen-unstable 12545:50467f56ed65 ported to 2.6.18-53.el5
Comment 10 Ian Campbell 2007-12-14 09:11:00 UTC 
Created attachment 288801 [details]
xen-unstable 13998:d2dff286994d ported to 2.6.18-53.el5
Comment 11 Ian Campbell 2007-12-14 09:12:21 UTC 
We recently stopped using the rhel4x.hg port from xenbits and switched to using
a set of targetted fixes to your kernels. I have attached the patches from our
queue relevant to this issue.

I'm not sure why it never occured to me to attach our rhel5x version of the
patches here (it seems a pretty obvious thing to do now I think about it!). I
see you've got a patch of your own now but I've attached our versions in case
they are of use.
Comment 12 Don Zickus 2008-01-10 20:42:35 UTC 
in 2.6.18-66.el5
You can download this test kernel from http://people.redhat.com/dzickus/el5
Comment 14 Scott LaCroix 2008-04-17 18:53:10 UTC 
Is there a fix for this in the PAE kernel as well? I am seeing the problem in
2.6.18-53PAE.

Thanks
Comment 15 Chris Lalancette 2008-04-17 19:03:45 UTC 
No, that doesn't make sense.  This is specifically for a RHEL-5 Xen PV kernel,
not for a bare-metal kernel.  You seem to be having a different issue; please
open a different BZ about it.

Chris Lalancette
Comment 16 John Madden 2008-04-25 19:07:31 UTC 
Don, do your more recent kernel builds still contain the fix?  I'm seeing this
bug and would be happy to test, just wanted to make sure they're patched
appropriately.
Comment 17 Chris Lalancette 2008-04-25 19:27:14 UTC 
Yep, these fixes should be in later 5.2 kernel builds.  Note that there were
additional patches that went into -89 to fix up a regression caused by this
patchset, so you'll want to test later than that.  Any testing is welcome!

Thanks,
Chris Lalancette
Comment 18 John Madden 2008-04-25 20:47:57 UTC 
Tested with -91, no failures.  This appears to fix the crash.
Comment 20 errata-xmlrpc 2008-05-21 14:55:27 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 the 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/RHBA-2008-0314.html