Subject: Re: [patch 3/3] arch_rebalance_pgtables call
From: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reply-To: schwidefsky@de.ibm.com
To: benh@kernel.crashing.org
Cc: Nick Piggin <nickpiggin@yahoo.com.au>, akpm@linux-foundation.org,
       linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org
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Organization: IBM Corporation
Date: Thu, 15 Nov 2007 18:13:06 +0100
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On Thu, 2007-11-15 at 09:07 +1100, Benjamin Herrenschmidt wrote:
> On Wed, 2007-11-14 at 12:49 +0100, Martin Schwidefsky wrote:
> > 
> > They all either have an arch override, call get_unmapped_area again or
> > are not relevant. So it should be possible to do the upgrade in
> > arch_get_unmapped_area. I still have my doubts though, all future uses
> > of the get_unmapped_area pointer have to be checked and I feel it is
> > easier to understand to do the upgrade / rebalance of the page table
> > at
> > the end of get_unmapped_area where every caller of mmap is guaranteed
> > to
> > pass through.
> 
> Well, if something does what you are worried about, then it would be
> broken on powerpc as well (among others). We have various constraints on
> the address space layout that must be handled by our arch g_u_a (or our
> hugetlb one).

Ok, I rearranged the dynamic page tables code (and fixed the bug that 31
bit processes had a 3 level page table instead of 2). It is working fine
with s390 specific versions of arch_get_unmapped_area and
arch_get_unmapped_area_topdown which do the page table upgrade. 

Which means we can drop the arch_rebalance_pgtables-call.patch from -mm
again.

-- 
blue skies,
  Martin.

"Reality continues to ruin my life." - Calvin.


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