[PATCH 2/2] mm: remove device private page support from hmm_range_fault

[Christoph Hellwig]

On Mon, Mar 16, 2020 at 11:42:19AM -0700, Ralph Campbell wrote:
>
> On 3/16/20 10:52 AM, Christoph Hellwig wrote:
>> No driver has actually used properly wire up and support this feature.
>> There is various code related to it in nouveau, but as far as I can tell
>> it never actually got turned on, and the only changes since the initial
>> commit are global cleanups.
>
> This is not actually true. OpenCL 2.x does support SVM with nouveau and
> device private memory via clEnqueueSVMMigrateMem().
> Also, Ben Skeggs has accepted a set of patches to map GPU memory after being
> migrated and this change would conflict with that.

Can you explain me how we actually invoke this code?

For that we'd need HMM_PFN_DEVICE_PRIVATE NVIF_VMM_PFNMAP_V0_VRAM
set in ->pfns before calling hmm_range_fault, which isn't happening.