Bug 681799

Summary:	[kdump] c000000068d79730: 00003eb27200000d __kstrtab_drm_mode_prune_invalid
Product:	Red Hat Enterprise Linux 6	Reporter:	Chao Ye <cye>
Component:	crash	Assignee:	Dave Anderson <anderson>
Status:	CLOSED NOTABUG	QA Contact:	Kernel Dump QE <kernel-dump-qe>
Severity:	unspecified	Docs Contact:
Priority:	unspecified
Version:	6.1	CC:	czhang, phan
Target Milestone:	rc
Target Release:	---
Hardware:	ppc64
OS:	Linux
Whiteboard:
Fixed In Version:		Doc Type:	Bug Fix
Doc Text:		Story Points:	---
Clone Of:		Environment:
Last Closed:	2011-03-04 13:44:04 UTC	Type:	---
Regression:	---	Mount Type:	---
Documentation:	---	CRM:
Verified Versions:		Category:	---
oVirt Team:	---	RHEL 7.3 requirements from Atomic Host:
Cloudforms Team:	---	Target Upstream Version:

Description Chao Ye 2011-03-03 09:44:47 UTC

Description of problem:
When run kdump test analyse-crash-live, got these output:
==============================================================
- only check the return code of this session.
- # crash  -i /mnt/testarea/crash-simple.cmd       

- also check command output of this session.
- # crash  -i /mnt/testarea/crash.cmd  

- skip the following patterns when searching for potential errors.
- 'error_'
- 'ERROR_'
- '-error'
- '_error'
- 'Data Access error'
- 'invalid float value'
- '_fail'
- 'failsafe'
- 'invalid_'
- 'invalidate'
- 'PCIBR error'
- 'TIOCE error'
- 'task_beah_unexpected'

- search for the following patterns for potential errors.
- 'fail'
- 'error'
- 'invalid'
- 'absurdly large unwind_info'
- 'unexpected'

c000000068d79730:  00003eb27200000d __kstrtab_drm_mode_prune_invalid 
c000000068d798e0:  000040c564000017 __ksymtab_drm_mode_prune_invalid 
c000000068d79a90:  000042d864000019 __kcrctab_drm_mode_prune_invalid 
- fail: crash commands have some failures.

Version-Release number of selected component (if applicable):
kernel-2.6.32-119.el6
crash-5.1.1-1.el6.ppc64

How reproducible:
ibm-js22-07.rhts.eng.bos.redhat.com

Steps to Reproduce:
1.Install RHEL6.1-20110224.2 on ibm-js22-07.rhts.eng.bos.redhat.com
2.Run analyse-crash-live
3.
  
Actual results:


Expected results:


Additional info:
https://beaker.engineering.redhat.com/recipes/119029

Comment 2 Dave Anderson 2011-03-03 13:57:15 UTC

> https://beaker.engineering.redhat.com/recipes/119029

That link shows this:
 
  Invalid R:119029, has been deleted

Anyway, my best guess is the the /mnt/testarea/crash.cmd command
list may be doing a "rd -s <address> <length>" command?  

"__kstrtab_drm_mode_prune_invalid" is just a symbol from the
 "drm" module:

  crash> sym __kstrtab_drm_mode_prune_invalid
  ffffffffa0066a4f (r) __kstrtab_drm_mode_prune_invalid [drm]
  crash>

And so if I search kernel virtual memory for all instances of
that value:
 
  crash> search -k ffffffffa0066a4f
  ffff88001f0b0b60: ffffffffa0066a4f
  ffff88001feadba8: ffffffffa0066a4f
  ffff8800206d0ba8: ffffffffa0066a4f
  ffff880035075040: ffffffffa0066a4f
  ffff880037d39898: ffffffffa0066a4f
  ffff880037d44708: ffffffffa0066a4f
  ffffffffa0065898: ffffffffa0066a4f
  ffffffffa0070708: ffffffffa0066a4f
  crash>

If I take any of memory addresses above, subtract 8, I can mimic your
output: 

> c000000068d79730:  00003eb27200000d __kstrtab_drm_mode_prune_invalid
> c000000068d798e0:  000040c564000017 __ksymtab_drm_mode_prune_invalid 
> c000000068d79a90:  000042d864000019 __kcrctab_drm_mode_prune_invalid

by doing this with "rd -s":

  crash> rd -s ffff880037d44700 2
  ffff880037d44700:  0019007200003d1c __kstrtab_drm_mode_prune_invalid 
  crash>

Aside from the fact that your output is from a ppc64 machine
and mine is x86_64, I'm presuming that your test is doing a
"rd -s" on a large chunk of memory, and bumping into instances
of that symbol value.  (and seeing "invalid" in the output)

In any case, that's certainly not a bug.

Comment 3 Chao Ye 2011-03-04 06:27:55 UTC

Tested on ibm-js22-07.rhts.eng.bos.redhat.com with kernel-2.6.32-119.el6/crash-5.1.1-1.el6.ppc64 again, no such issue was found.

https://beaker.engineering.redhat.com/jobs/58856

Comment 4 Dave Anderson 2011-03-04 13:44:04 UTC

> Tested on ibm-js22-07.rhts.eng.bos.redhat.com with
> kernel-2.6.32-119.el6/crash-5.1.1-1.el6.ppc64 again, no such issue was found.

Do you not understand my comment #2?  There is no *issue* to begin with.  

When you ran the test a second time, by luck it did not "rd -s" any
memory that contained the  __kcrctab_drm_mode_prune_invalid
symbol.

It is NOT a bug -- you have to fix your test program.
You cannot simply "grep invalid" the output of all crash commands,
because it will pick up legitimate output like this.