Bug 448598 - CONFIG_DEBUG_PAGEALLOC doesn't work on ppc32 [NEEDINFO]
Summary: CONFIG_DEBUG_PAGEALLOC doesn't work on ppc32
Alias: None
Product: Fedora
Classification: Fedora
Component: kernel
Version: 10
Hardware: powerpc
OS: Linux
Target Milestone: ---
Assignee: Kernel Maintainer List
QA Contact: Fedora Extras Quality Assurance
Depends On:
TreeView+ depends on / blocked
Reported: 2008-05-27 19:23 UTC by Jesse Keating
Modified: 2013-01-10 03:20 UTC (History)
5 users (show)

Fixed In Version:
Doc Type: Bug Fix
Doc Text:
Clone Of:
Last Closed: 2009-12-18 06:10:20 UTC
poelstra: needinfo? (kernel-maint)

Attachments (Terms of Use)
Photo of oops (1.12 MB, image/jpeg)
2008-05-27 19:23 UTC, Jesse Keating
no flags Details
Another oops with selinux=0 (1.07 MB, image/jpeg)
2008-05-27 19:42 UTC, Jesse Keating
no flags Details
powerpc32 UP config (80.69 KB, text/plain)
2008-05-28 01:16 UTC, Josh Boyer
no flags Details

Description Jesse Keating 2008-05-27 19:23:10 UTC
I'm getting oopses from the kernel on a ppc mac mini with rawhide kernel. 
Fedora 9 installs and runs fine, it's only after rebooting to the rawhide kernel
that I start getting oopses.  I've attached a photo from the screen, I can get
more if necessary.

Comment 1 Jesse Keating 2008-05-27 19:23:11 UTC
Created attachment 306824 [details]
Photo of oops

Comment 2 Dave Jones 2008-05-27 19:40:58 UTC
This only just started happening because I turned on PAGEALLOC_DEBUG for all archs.

There was an exception in the ppc config disabling this, which meant that it
never got tested during F9 development at all.

Looking at the oops, I'm wondering if this feature is just busted on PPC, and
that's why it was explicitly disabled, rather than inheriting the setting from

Comment 3 Jesse Keating 2008-05-27 19:42:47 UTC
Created attachment 306826 [details]
Another oops with selinux=0

I was asked to boot with selinux=0 and I got farther.

Comment 4 Josh Boyer 2008-05-28 01:00:13 UTC
Added Ben to CC.  Perhaps he can decipher some of the mysticism behind why
PAGEALLOC_DEBUG wasn't set in the past.

Comment 5 Josh Boyer 2008-05-28 01:16:15 UTC
Created attachment 306871 [details]
powerpc32 UP config

This should be the .config file that is used with the rawhide kernels.

Comment 6 Benjamin Herrenschmidt 2008-05-28 09:38:09 UTC
I'll have a look tomorrow. In the meantime, fedora should disable it for 32 bits
powerpc (64 bits should be allright). Appart from the problem reported, there
are known issues with DEBUG_PAGEALLOC on ppc32 SMP for example. I have some
plans to fix that but in the meantime, it's probably better to disable the whole

Comment 7 Dave Jones 2008-06-04 18:46:55 UTC
Disabled on ppc32 for now.

Comment 8 John Poelstra 2008-10-15 23:25:12 UTC
Per comment #7.  Is this bug resolved?

This bug has been triaged

Comment 9 Dave Jones 2008-10-16 15:19:14 UTC
John, upstream is still broken, but when we enabled this option during development we explicitly disabled it on ppc32.  It's likely we'll do the same thing when F11 opens up for devel, and continue doing so until upstream supports DEBUG_PAGEALLOC

Comment 10 Benjamin Herrenschmidt 2008-10-16 22:22:37 UTC
Dave: that's probably the way to go. It's going to take time to fix that one, because of the way ppc32 "classic MMU" works. We map the kernel linear mapping using a specific CPU facility to create huge fixed mappings that is fundamentally incompatible with DEBUG_PAGEALLOC, and we have some areas where the code assumes that mapping (ie, it assumes it cannot take an MMU hash miss) on linear mapping accesses. It's possible to "fix" but tricky and nobody so far had time to work on it.

Comment 11 Bug Zapper 2008-11-26 02:20:28 UTC
This bug appears to have been reported against 'rawhide' during the Fedora 10 development cycle.
Changing version to '10'.

More information and reason for this action is here:

Comment 12 Jesse Keating 2009-02-06 02:02:53 UTC
So what's the status on this one?

Comment 13 Bug Zapper 2009-11-18 12:31:21 UTC
This message is a reminder that Fedora 10 is nearing its end of life.
Approximately 30 (thirty) days from now Fedora will stop maintaining
and issuing updates for Fedora 10.  It is Fedora's policy to close all
bug reports from releases that are no longer maintained.  At that time
this bug will be closed as WONTFIX if it remains open with a Fedora 
'version' of '10'.

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Comment 14 Bug Zapper 2009-12-18 06:10:20 UTC
Fedora 10 changed to end-of-life (EOL) status on 2009-12-17. Fedora 10 is 
no longer maintained, which means that it will not receive any further 
security or bug fix updates. As a result we are closing this bug.

If you can reproduce this bug against a currently maintained version of 
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