Re: [PATCH] drm/xe: Tie page count tracepoints to TTM accounting functions

["Summers, Stuart" <stuart.summers@intel.com>]

On Tue, 2026-01-06 at 16:21 -0800, Matthew Brost wrote:
> Page accounting can change via the shrinker without calling
> xe_ttm_tt_unpopulate(), but those paths already update accounting
> through the xe_ttm_tt_account_*() helpers.

I see this is getting also called through the xe_bo_pin/unpin functions
with a check for ttm_tt_is_populated(). Does that mean after this
change we'd get a double accounting in those cases?

Thanks,
Stuart

> 
> Move the page count tracepoints into xe_ttm_tt_account_add() and
> xe_ttm_tt_account_subtract() so accounting updates are recorded
> consistently, regardless of whether pages are populated, unpopulated,
> or reclaimed via the shrinker.
> 
> This avoids missing page count updates and keeps global accounting
> balanced across all TT lifecycle paths.
> 
> Cc: stable@vger.kernel.org
> Fixes: ce3d39fae3d3 ("drm/xe/bo: add GPU memory trace points")
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>  drivers/gpu/drm/xe/xe_bo.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
> index 8b6474cd3eaf..33afaee38f48 100644
> --- a/drivers/gpu/drm/xe/xe_bo.c
> +++ b/drivers/gpu/drm/xe/xe_bo.c
> @@ -432,6 +432,9 @@ struct sg_table *xe_bo_sg(struct xe_bo *bo)
>         return xe_tt->sg;
>  }
>  
> +static void update_global_total_pages(struct ttm_device *ttm_dev,
> +                                     long num_pages);
> +
>  /*
>   * Account ttm pages against the device shrinker's shrinkable and
>   * purgeable counts.
> @@ -440,6 +443,7 @@ static void xe_ttm_tt_account_add(struct
> xe_device *xe, struct ttm_tt *tt)
>  {
>         struct xe_ttm_tt *xe_tt = container_of(tt, struct xe_ttm_tt,
> ttm);
>  
> +       update_global_total_pages(&xe->ttm, tt->num_pages);
>         if (xe_tt->purgeable)
>                 xe_shrinker_mod_pages(xe->mem.shrinker, 0, tt-
> >num_pages);
>         else
> @@ -450,6 +454,7 @@ static void xe_ttm_tt_account_subtract(struct
> xe_device *xe, struct ttm_tt *tt)
>  {
>         struct xe_ttm_tt *xe_tt = container_of(tt, struct xe_ttm_tt,
> ttm);
>  
> +       update_global_total_pages(&xe->ttm, -(long)tt->num_pages);
>         if (xe_tt->purgeable)
>                 xe_shrinker_mod_pages(xe->mem.shrinker, 0, -(long)tt-
> >num_pages);
>         else
> @@ -575,7 +580,6 @@ static int xe_ttm_tt_populate(struct ttm_device
> *ttm_dev, struct ttm_tt *tt,
>  
>         xe_tt->purgeable = false;
>         xe_ttm_tt_account_add(ttm_to_xe_device(ttm_dev), tt);
> -       update_global_total_pages(ttm_dev, tt->num_pages);
>  
>         return 0;
>  }
> @@ -592,7 +596,6 @@ static void xe_ttm_tt_unpopulate(struct
> ttm_device *ttm_dev, struct ttm_tt *tt)
>  
>         ttm_pool_free(&ttm_dev->pool, tt);
>         xe_ttm_tt_account_subtract(xe, tt);
> -       update_global_total_pages(ttm_dev, -(long)tt->num_pages);
>  }
>  
>  static void xe_ttm_tt_destroy(struct ttm_device *ttm_dev, struct
> ttm_tt *tt)