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Date: Wed, 23 Apr 2008 11:27:21 -0700 (PDT)
From: Christoph Lameter <clameter@sgi.com>
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To: Andrea Arcangeli <andrea@qumranet.com>
cc: Robin Holt <holt@sgi.com>, Nick Piggin <npiggin@suse.de>,
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Subject: Re: [PATCH 01 of 12] Core of mmu notifiers
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On Wed, 23 Apr 2008, Andrea Arcangeli wrote:

> On Wed, Apr 23, 2008 at 11:09:35AM -0700, Christoph Lameter wrote:
> > Why is there still the hlist stuff being used for the mmu notifier list? 
> > And why is this still unsafe?
> 
> What's the problem with hlist, it saves 8 bytes for each mm_struct,
> you should be using it too instead of list.

list heads in mm_struct and in the mmu_notifier struct seemed to 
be more consistent. We have no hash list after all.

> 
> > There are cases in which you do not take the reverse map locks or mmap_sem
> > while traversing the notifier list?
> 
> There aren't.

There is a potential issue in move_ptes where you call 
invalidate_range_end after dropping i_mmap_sem whereas my patches did the 
opposite. Mmap_sem saves you there?