Re: [PATCH] drm/ttm: Fix ttm_bo_shrink() infinite LRU walk on backup failure

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

On 11/05/2026 17:24, Thomas Hellström wrote:
> Apply the same fix as b2ed01e7ad ("drm/ttm: Fix ttm_bo_swapout()
> infinite LRU walk on swapout failure") to the ttm_bo_shrink() path.
> 
> Move del_bulk_move from before the backup to after success only,
> using ttm_resource_del_bulk_move_unevictable() since the resource
> is now unevictable once fully backed up.
> 
> Fixes: 70d645deac98 ("drm/ttm: Add helpers for shrinking")
> Cc: Christian König <christian.koenig@amd.com>
> Cc: Huang Rui <ray.huang@amd.com>
> Cc: Matthew Auld <matthew.auld@intel.com>
> Cc: Matthew Brost <matthew.brost@intel.com>
> Cc: Dave Airlie <airlied@redhat.com>
> Cc: dri-devel@lists.freedesktop.org
> Cc: <stable@vger.kernel.org> # v6.15+
> Assisted-by: GitHub_Copilot:claude-opus-4.6
> Signed-off-by: Thomas Hellström <thomas.hellstrom@linux.intel.com>

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

> ---
>   drivers/gpu/drm/ttm/ttm_bo_util.c | 11 +++--------
>   1 file changed, 3 insertions(+), 8 deletions(-)
> 
> diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
> index f83b7d5ec6c6..3e3c201a0222 100644
> --- a/drivers/gpu/drm/ttm/ttm_bo_util.c
> +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
> @@ -1112,19 +1112,14 @@ long ttm_bo_shrink(struct ttm_operation_ctx *ctx, struct ttm_buffer_object *bo,
>   	if (lret < 0)
>   		return lret;
>   
> -	if (bo->bulk_move) {
> -		spin_lock(&bdev->lru_lock);
> -		ttm_resource_del_bulk_move(bo->resource, bo);
> -		spin_unlock(&bdev->lru_lock);
> -	}
> -
>   	lret = ttm_tt_backup(bdev, bo->ttm, (struct ttm_backup_flags)
>   			     {.purge = flags.purge,
>   			      .writeback = flags.writeback});
>   
> -	if (lret <= 0 && bo->bulk_move) {
> +	if (lret > 0) {
>   		spin_lock(&bdev->lru_lock);
> -		ttm_resource_add_bulk_move(bo->resource, bo);
> +		ttm_resource_del_bulk_move_unevictable(bo->resource, bo);
> +		ttm_resource_move_to_lru_tail(bo->resource);
>   		spin_unlock(&bdev->lru_lock);
>   	}
>