[RFC] mm/hmm: pass mmu_notifier_range to sync_cpu_device_pagetables

Ralph Campbell rcampbell at nvidia.com
Tue Jul 2 20:11:28 UTC 2019

On 7/2/19 12:53 PM, Jason Gunthorpe wrote:
> 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
Not from me. :-)


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