Re: [PATCH 05/10] drm/ttm: switch to ttm_bo_lru_for_each_reserved_guarded for swapout

[Thomas Hellström]

On Fri, 2026-07-03 at 18:31 +0200, Natalie Vock wrote:
> From: Christian König <christian.koenig@xxxxxxx>
> 
> Instead of the walker wrapper use the underlying foreach. Saves us
> quite
> a bunch of complexity and loc.
> 
> Signed-off-by: Christian König <christian.koenig@xxxxxxx>
> Signed-off-by: Natalie Vock <natalie.vock@xxxxxx>

Reviewed-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>


> ---
>  drivers/gpu/drm/ttm/ttm_bo.c     | 58 +++++++-----------------------
> ----------
>  drivers/gpu/drm/ttm/ttm_device.c | 19 ++++++++++---
>  include/drm/ttm/ttm_bo.h         |  5 ++--
>  3 files changed, 27 insertions(+), 55 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo.c
> b/drivers/gpu/drm/ttm/ttm_bo.c
> index 1fb8c53da0362..24c52df169ac8 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo.c
> @@ -1080,25 +1080,18 @@ int ttm_bo_wait_ctx(struct ttm_buffer_object
> *bo, struct ttm_operation_ctx *ctx)
>  EXPORT_SYMBOL(ttm_bo_wait_ctx);
>  
>  /**
> - * struct ttm_bo_swapout_walk - Parameters for the swapout walk
> + * ttm_bo_swapout() - Swap out buffer objects on the LRU list to
> shmem.
> + * @bo: The buffer to swap out.
> + * @ctx: The ttm_operation_ctx governing the swapout operation.
> + * @gfp_flags: The gfp flags used for shmem page allocations.
> + *
> + * Return: The number of bytes actually swapped out, or negative
> error code
> + * on error.
>   */
> -struct ttm_bo_swapout_walk {
> -	/** @walk: The walk base parameters. */
> -	struct ttm_lru_walk walk;
> -	/** @gfp_flags: The gfp flags to use for ttm_tt_swapout() */
> -	gfp_t gfp_flags;
> -	/** @hit_low: Whether we should attempt to swap BO's with
> low watermark threshold */
> -	/** @evict_low: If we cannot swap a bo when @try_low is
> false (first pass) */
> -	bool hit_low, evict_low;
> -};
> -
> -static s64
> -ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct
> ttm_buffer_object *bo)
> +s64 ttm_bo_swapout(struct ttm_buffer_object *bo, struct
> ttm_operation_ctx *ctx,
> +		   gfp_t gfp_flags)
>  {
>  	struct ttm_place place = { .mem_type = bo->resource-
> >mem_type };
> -	struct ttm_bo_swapout_walk *swapout_walk =
> -		container_of(walk, typeof(*swapout_walk), walk);
> -	struct ttm_operation_ctx *ctx = walk->arg.ctx;
>  	struct ttm_device *bdev = bo->bdev;
>  	struct ttm_tt *tt = bo->ttm;
>  	s64 ret;
> @@ -1166,7 +1159,7 @@ ttm_bo_swapout_cb(struct ttm_lru_walk *walk,
> struct ttm_buffer_object *bo)
>  		bdev->funcs->swap_notify(bo);
>  
>  	if (ttm_tt_is_populated(tt)) {
> -		ret = ttm_tt_swapout(bdev, tt, swapout_walk-
> >gfp_flags);
> +		ret = ttm_tt_swapout(bdev, tt, gfp_flags);
>  		if (!ret) {
>  			spin_lock(&bdev->lru_lock);
>  			ttm_resource_del_bulk_move_unevictable(bo-
> >resource, bo);
> @@ -1183,37 +1176,6 @@ ttm_bo_swapout_cb(struct ttm_lru_walk *walk,
> struct ttm_buffer_object *bo)
>  	return ret;
>  }
>  
> -/**
> - * ttm_bo_swapout() - Swap out buffer objects on the LRU list to
> shmem.
> - * @bdev: The ttm device.
> - * @ctx: The ttm_operation_ctx governing the swapout operation.
> - * @man: The resource manager whose resources / buffer objects are
> - * goint to be swapped out.
> - * @gfp_flags: The gfp flags used for shmem page allocations.
> - * @target: The desired number of pages to swap out.
> - *
> - * Return: The number of pages actually swapped out, or negative
> error code
> - * on error.
> - */
> -s64 ttm_bo_swapout(struct ttm_device *bdev, struct ttm_operation_ctx
> *ctx,
> -		   struct ttm_resource_manager *man, gfp_t
> gfp_flags,
> -		   s64 target)
> -{
> -	struct ttm_bo_swapout_walk swapout_walk = {
> -		.walk = {
> -			.process_bo = ttm_bo_swapout_cb,
> -			.arg = {
> -				.ctx = ctx,
> -				.trylock_only = true,
> -			},
> -		},
> -		.gfp_flags = gfp_flags,
> -	};
> -
> -	return ttm_lru_walk_for_evict(&swapout_walk.walk, bdev, man,
> target);
> -}
> -EXPORT_SYMBOL_FOR_TESTS_ONLY(ttm_bo_swapout);
> -
>  void ttm_bo_tt_destroy(struct ttm_buffer_object *bo)
>  {
>  	if (bo->ttm == NULL)
> diff --git a/drivers/gpu/drm/ttm/ttm_device.c
> b/drivers/gpu/drm/ttm/ttm_device.c
> index d3bfb9a696a74..e4188e2ee7ab1 100644
> --- a/drivers/gpu/drm/ttm/ttm_device.c
> +++ b/drivers/gpu/drm/ttm/ttm_device.c
> @@ -171,6 +171,12 @@ int ttm_device_swapout(struct ttm_device *bdev,
> struct ttm_operation_ctx *ctx,
>  		       gfp_t gfp_flags)
>  {
>  	struct ttm_resource_manager *man;
> +	struct ttm_bo_lru_cursor cursor;
> +	struct ttm_buffer_object *bo;
> +	struct ttm_lru_walk_arg arg = {
> +		.ctx = ctx,
> +		.trylock_only = true
> +	};
>  	unsigned i;
>  	s64 lret;
>  
> @@ -179,10 +185,15 @@ int ttm_device_swapout(struct ttm_device *bdev,
> struct ttm_operation_ctx *ctx,
>  		if (!man || !man->use_tt)
>  			continue;
>  
> -		lret = ttm_bo_swapout(bdev, ctx, man, gfp_flags, 1);
> -		/* Can be both positive (num_pages) and negative
> (error) */
> -		if (lret)
> -			return lret;
> +		ttm_bo_lru_for_each_reserved_guarded(&cursor, man,
> &arg, bo) {
> +			lret = ttm_bo_swapout(bo, ctx, gfp_flags);
> +				continue;
> +			/* Can be both positive (num_pages) and
> negative (error) */
> +			if (lret && lret != -EBUSY && lret != -
> EALREADY)
> +				return lret;
> +		}
> +		if (IS_ERR(bo))
> +			return PTR_ERR(bo);
>  	}
>  	return 0;
>  }
> diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h
> index 0fcd5082a7080..bbed63064c9a9 100644
> --- a/include/drm/ttm/ttm_bo.h
> +++ b/include/drm/ttm/ttm_bo.h
> @@ -408,9 +408,8 @@ void *ttm_bo_kmap_try_from_panic(struct
> ttm_buffer_object *bo, unsigned long pag
>  int ttm_bo_vmap(struct ttm_buffer_object *bo, struct iosys_map
> *map);
>  void ttm_bo_vunmap(struct ttm_buffer_object *bo, struct iosys_map
> *map);
>  int ttm_bo_mmap_obj(struct vm_area_struct *vma, struct
> ttm_buffer_object *bo);
> -s64 ttm_bo_swapout(struct ttm_device *bdev, struct ttm_operation_ctx
> *ctx,
> -		   struct ttm_resource_manager *man, gfp_t
> gfp_flags,
> -		   s64 target);
> +s64 ttm_bo_swapout(struct ttm_buffer_object *bo, struct
> ttm_operation_ctx *ctx,
> +		   gfp_t gfp_flags);
>  void ttm_bo_pin(struct ttm_buffer_object *bo);
>  void ttm_bo_unpin(struct ttm_buffer_object *bo);
>  int ttm_bo_evict_first(struct ttm_device *bdev,