Re: [V4] drm/xe: Skip clearing purged page-table BOs

[Matthew Brost <matthew.brost@intel.com>]

On Wed, Sep 09, 2026 at 04:46:21PM +0530, Tejas Upadhyay wrote:
> VRAM page offlining can clear a page-table BO's vmap before VM teardown
> calls xe_pt_clear(). Check for a purged BO under its dma-resv lock before
> writing to the mapping.
> 
> v4(Sashiko):
> - dont leave svm notifier lock early
> v3(Sashiko):
> - Validate NULL vmap
> v2(Sashiko):
> - Fix lock ordering
> 
> Signed-off-by: Tejas Upadhyay <tejas.upadhyay@intel.com>

Reviewed-by: Matthew Brost <matthew.brost@intel.com>

> ---
>  drivers/gpu/drm/xe/xe_pt.c | 6 ++++--
>  drivers/gpu/drm/xe/xe_vm.c | 4 ++++
>  2 files changed, 8 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_pt.c b/drivers/gpu/drm/xe/xe_pt.c
> index 7fb2fe1f826c..4b351dbf6572 100644
> --- a/drivers/gpu/drm/xe/xe_pt.c
> +++ b/drivers/gpu/drm/xe/xe_pt.c
> @@ -236,9 +236,11 @@ void xe_pt_destroy(struct xe_pt *pt, u32 flags, struct llist_head *deferred)
>   */
>  void xe_pt_clear(struct xe_device *xe, struct xe_pt *pt)
>  {
> -	struct iosys_map *map = &pt->bo->vmap;
> +	struct xe_bo *bo = pt->bo;
>  
> -	xe_map_memset(xe, map, 0, 0, SZ_4K);
> +	xe_bo_assert_held(bo);
> +	if (!iosys_map_is_null(&bo->vmap))
> +		xe_map_memset(xe, &bo->vmap, 0, 0, SZ_4K);
>  }
>  
>  /**
> diff --git a/drivers/gpu/drm/xe/xe_vm.c b/drivers/gpu/drm/xe/xe_vm.c
> index 9e71567b27cc..efa5ff6cc823 100644
> --- a/drivers/gpu/drm/xe/xe_vm.c
> +++ b/drivers/gpu/drm/xe/xe_vm.c
> @@ -1876,6 +1876,8 @@ static void xe_vm_close(struct xe_vm *vm)
>  	bound = drm_dev_enter(&xe->drm, &idx);
>  
>  	down_write(&vm->lock);
> +	xe_vm_lock(vm, false);
> +
>  	if (xe_vm_in_fault_mode(vm))
>  		xe_svm_notifier_lock(vm);
>  
> @@ -1903,6 +1905,8 @@ static void xe_vm_close(struct xe_vm *vm)
>  
>  	if (xe_vm_in_fault_mode(vm))
>  		xe_svm_notifier_unlock(vm);
> +
> +	xe_vm_unlock(vm);
>  	up_write(&vm->lock);
>  
>  	if (bound)
> -- 
> 2.52.0
>