[RFC] mm/hmm: pass mmu_notifier_range to sync_cpu_device_pagetables

[Jason Gunthorpe]

On Fri, Jun 07, 2019 at 05:14:52PM -0700, Ralph Campbell wrote:
> HMM defines its own struct hmm_update which is passed to the
> sync_cpu_device_pagetables() callback function. This is
> sufficient when the only action is to invalidate. However,
> a device may want to know the reason for the invalidation and
> be able to see the new permissions on a range, update device access
> rights or range statistics. Since sync_cpu_device_pagetables()
> can be called from try_to_unmap(), the mmap_sem may not be held
> and find_vma() is not safe to be called.
> Pass the struct mmu_notifier_range to sync_cpu_device_pagetables()
> to allow the full invalidation information to be used.
> 
> Signed-off-by: Ralph Campbell <rcampbell at nvidia.com>
> ---
> 
> I'm sending this out now since we are updating many of the HMM APIs
> and I think it will be useful.

This make so much sense, I'd like to apply this in hmm.git, is there
any objection?

Jason