Re: [PATCH v6 1/3] drm/xe: Bump the LRU on a successful page fault

[Matthew Auld <matthew.auld@intel.com>]

On 27/10/2026 22:49, Matthew Brost wrote:
> Servicing a page fault validates the VMA's backing store and binds it,
> making the BO part of the VM's active working set, but unlike exec it
> never moves anything on the TTM LRU. In fault mode, where a VM may run
> for a long time without a single exec, the BOs the GPU actually touches
> therefore drift towards the LRU head and are picked by eviction and by
> the shrinker ahead of genuinely cold BOs.
> 
> Bump the BO's LRU on a successful page fault.
> 
> Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_pagefault.c | 7 +++++++
>   1 file changed, 7 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_pagefault.c b/drivers/gpu/drm/xe/xe_pagefault.c
> index 5247321c805e..6828f81df50e 100644
> --- a/drivers/gpu/drm/xe/xe_pagefault.c
> +++ b/drivers/gpu/drm/xe/xe_pagefault.c
> @@ -201,6 +201,8 @@ static int xe_pagefault_handle_vma(struct xe_gt *gt, struct xe_vma *vma,
>   		xe_validation_ctx_init(&ctx, &vm->xe->val, &exec,
>   				       (struct xe_val_flags) {});
>   		drm_exec_until_all_locked(&exec) {
> +			struct xe_bo *bo = xe_vma_bo(vma);
> +
>   			err = xe_pagefault_begin(&exec, vma, tile->mem.vram,
>   						 needs_vram == 1);
>   			drm_exec_retry_on_contention(&exec);
> @@ -221,6 +223,11 @@ static int xe_pagefault_handle_vma(struct xe_gt *gt, struct xe_vma *vma,
>   				xe_pagefault_set_error(pf, XE_PAGEFAULT_ERROR_VMA_REBIND);
>   				break;
>   			}
> +
> +			if (bo) {
> +				scoped_guard(spinlock, &vm->xe->ttm.lru_lock)
> +					ttm_bo_move_to_lru_tail(&bo->ttm);

Would it be cleaner to just use ttm_bo_move_to_lru_tail_unlocked() 
without the scoped guard stuff?

Reviewed-by: Matthew Auld <matthew.auld@intel.com>

> +			}
>   		}
>   		xe_validation_ctx_fini(&ctx);
>   	} while (err == -EAGAIN);