Bug 684957

Summary: RHEL6.1-Alpha: kABI breakage on UV
Product: Red Hat Enterprise Linux 6 Reporter: Russ Anderson <rja>
Component: kernelAssignee: George Beshers <gbeshers>
Status: CLOSED ERRATA QA Contact: Red Hat Kernel QE team <kernel-qe>
Severity: urgent Docs Contact:
Priority: unspecified    
Version: 6.1CC: dwa, gbeshers, gbeshers, martinez, mzywusko, rja
Target Milestone: rcKeywords: OtherQA, Regression
Target Release: ---   
Hardware: x86_64   
OS: Linux   
Whiteboard:
Fixed In Version: kernel-2.6.32-130.el6 Doc Type: Bug Fix
Doc Text:
Story Points: ---
Clone Of: Environment:
Last Closed: 2011-05-19 12:00:45 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: 645474    
Attachments:
Description Flags
Fix for the kABI breakage. none

Description Russ Anderson 2011-03-14 20:58:39 UTC 
Description of problem:

There is a RHEL6.1 kABI breakage on SGI UV.  Some idiot (me) pushed a patch to the community that added a field to uv_hub_info_s.  The community does not care about maintaining a stable ABI so the change was accepted.  Since RHEL does care about maintaining kABI this is a problem.  The impact is that modules built against the RHEL6.0 kernel that use the uv_hub_info structure will not load on the RHEL6.1 kernel.

This breakage was uncovered when trying to install modules built against RHEL6 onto a RHEL6.1-alpha system.  Before receiving the RHEL6.1-alpha testing was done with an internally build kernel & modules so the modules & kernel matched.

The upstream patch that caused the problem is http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=commitdiffh=c8f730b1ab825f06733e1c074264f0078721f365 .


Version-Release number of selected component (if applicable):


How reproducible:

100%.


Steps to Reproduce:
1. Boot the RHEL6.1-alpha kernel.
2. Try to load a module built on RHEL6.0 that uses the uv_hub_info structure.
  
Actual results:

The module will not load.

Expected results:

The module should load.

Additional info:

Attached is a patch to fix the problem.
Comment 2 Russ Anderson 2011-03-17 19:11:20 UTC 
Created attachment 486084 [details]
Fix for the kABI breakage.

This patch fixes the kABI breakage on SGI UV.
Comment 4 Russ Anderson 2011-03-25 17:28:50 UTC 
What is the status of this patch?  Last I heard George posted the patch on
the RH kernel list and answered a question by Don Z.  Is this patch in?
Thanks.
Comment 5 Marizol Martinez 2011-03-25 17:58:14 UTC 
And in addition to that, Russ, this BZ needs acks. George knows the process.
Comment 6 RHEL Program Management 2011-03-25 18:19:38 UTC 
This request was evaluated by Red Hat Product Management for inclusion
in a Red Hat Enterprise Linux maintenance release. Product Management has 
requested further review of this request by Red Hat Engineering, for potential
inclusion in a Red Hat Enterprise Linux Update release for currently deployed 
products. This request is not yet committed for inclusion in an Update release.
Comment 7 gbeshers 2011-03-25 18:23:35 UTC 
Well it did :)

I will ping developers.

The following is is in response to Don's question on rh-kernel.

======

Hi Don,

SGI has several kernel modules that are loaded on top of the RHEL
kernels which exploit features of our NUMA hardware.  The KABI
issue in question is SGI specific code which these modules rely
on.  Our concern is that when customers upgrade to 6.1 the
old modules work.

In the interest of full disclosure UV2 may cause us to have to
break KABI for 6.2, the point is under discussion inside SGI.
But it would be best if we don't have force an upgrade for 6.1
on UV1.  For one thing, it saves the kernel team work and
for another it makes calls to RedHat support for SGI problems
less likely :).

Cheers,
George
Comment 9 Aristeu Rozanski 2011-04-07 13:51:11 UTC 
Patch(es) available on kernel-2.6.32-130.el6
Comment 12 Russ Anderson 2011-04-08 20:14:43 UTC 
Verified fixed in kernel-2.6.32-130.el6.
SGI modules now load cleanly.

Thanks!
Comment 13 errata-xmlrpc 2011-05-19 12:00:45 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-2011-0542.html