[ofa-general] Re: [PATCH 01 of 12] Core of mmu notifiers

Christoph Lameter
2008-04-23T18:27:21Z

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?