pseries (power3) boot hang (pageblock_nr_pages==0)

[Will Schmidt]

On Wed, 2007-11-21 at 22:03 +0000, Mel Gorman wrote:
> On (21/11/07 15:55), Will Schmidt didst pronounce:
> > Hi Folks, 
> > 
> > I imagine this would be properly fixed with something similar to the
> > change for iSeries.  
> 
> Have you tried with the patch that fixed the iSeries boot problem?
> Thanks for tracking down the problem to such a specific place.

I had not, but gave this patch a spin this morning, and it does the
job.  :-)    I was thinking (without really looking at it), that the
iseries fix was in platform specific code.   Silly me. :-)

So for the record, this patch also fixes power3 pSeries systems.

fwiw:
Tested-By:  Will Schmidt <will_schmidt at vnet.ibm.com>

Thanks, 

-Will


> ======
> 
> Ordinarily, the size of a pageblock is determined at compile-time based on
> the hugepage size. On PPC64, the hugepage size is determined at runtime based
> on what is supported by the machine. On legacy machines such as iSeries which
> do not support hugepages, HPAGE_SHIFT is 0. This results in pageblock_order
> being set to -PAGE_SHIFT and a crash results shortly afterwards.
> 
> This patch checks that HPAGE_SHIFT is a sensible value before using the
> hugepage size. If it is 0, MAX_ORDER-1 is used instead as this is a sensible
> value of pageblock_order.
> 
> This is a fix for 2.6.24.
> 
> Credit goes to Stephen Rothwell for identifying the bug and testing on
> iSeries.  Additional credit goes to David Gibson for testing with the
> libhugetlbfs test suite.
> 
> Signed-off-by: Mel Gorman <mel at csn.ul.ie>
> 
> ---