[PATCH] drm/amdkfd: ignore userptr NUMA auto balancing event

[Felix Kuehling]

MMU_NOTIFY_PROTECTION_VMA is not specific to NUMA auto-balancing. It can
also be the result of an mprotect system call which actually makes the
VMA read-only. I don't think it's OK to ignore that notifier in the
general case.

Regards,
  Felix


Am 2020-08-19 um 2:00 p.m. schrieb Philip Yang:
> NUMA auto balancing task_numa_work periodically change memory range
> protection proto, in order to trigger CPU page hinting fault when CPU
> access the memory later to check if that memory range need to migrate to
> different NUMA node.
>
> GPU can still access the memory after NUMA change the proto because the
> memory is not moved yet, so it is safe to ignore the MMU notifier event
> MMU_NOTIFY_PROTECTION_VMA to avoid unnecessary queue eviction and
> restore.
>
> Before NUMA auto balancing actually move the memory to different NUMA
> node, driver will receive MMU notifier event MMU_NOTIFY_CLEAR to evict
> the queues.
>
> Signed-off-by: Philip Yang <Philip.Yang at amd.com>
> ---
>  drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
> index 828b5167ff12..dc4e2317dc31 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_mn.c
> @@ -106,6 +106,8 @@ static bool amdgpu_mn_invalidate_hsa(struct mmu_interval_notifier *mni,
>  
>  	if (!mmu_notifier_range_blockable(range))
>  		return false;
> +	if (range->event == MMU_NOTIFY_PROTECTION_VMA)
> +		return true;
>  
>  	mutex_lock(&adev->notifier_lock);
>