Re: [PATCH v3 0/2] drm/amdkfd: Unmap SVM range from GPU set to no-access

On 2026-07-29 12:35, Philip Yang wrote:
> Setting KFD_IOCTL_SVM_ATTR_NO_ACCESS on a GPU used to do nothing: the
> range stayed mapped, so the MMU notifier kept evicting GPU queues on CPU
> page faults even though the app wanted no access from that GPU.
>
> Patch 1 adds a helper to update the fault checkpoint timestamp and makes
> the timestamp atomic so the page fault handler can read it locklessly.
>
> Patch 2 unmaps the range from each GPU set to no-access. Once no GPU maps
> the range, the MMU notifier skips queue eviction. It bumps the checkpoint
> timestamp so retry faults queued before the unmap are dropped.
>
> v3:
>   - Patch 1: fix checkpoint_ts atomic double-read race
>   - Patch 2: move checkpoint timestamp update into svm_range_needs_unmap

The series is

Reviewed-by: Felix Kuehling <[email protected]>


>
> Philip Yang (2):
>    drm/amdkfd: Add helper svm_range_update_checkpoint_timestamp
>    drm/amdkfd: Unmap svm range from GPU set to no-access
>
>   drivers/gpu/drm/amd/amdkfd/kfd_priv.h  |   2 +-
>   drivers/gpu/drm/amd/amdkfd/kfd_queue.c |   5 +-
>   drivers/gpu/drm/amd/amdkfd/kfd_svm.c   | 191 +++++++++++++++----------
>   drivers/gpu/drm/amd/amdkfd/kfd_svm.h   |   7 +-
>   4 files changed, 126 insertions(+), 79 deletions(-)
>