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

[kernel test robot <lkp@intel.com>]

Hi Thomas,

kernel test robot noticed the following build errors:

[auto build test ERROR on drm-misc/drm-misc-next]
[also build test ERROR on linus/master v7.1-rc3 next-20260508]
[If your patch is applied to the wrong git tree, kindly drop us a note.
And when submitting patch, we suggest to use '--base' as documented in
https://git-scm.com/docs/git-format-patch#_base_tree_information]

url:    https://github.com/intel-lab-lkp/linux/commits/Thomas-Hellstr-m/drm-ttm-Fix-ttm_bo_shrink-infinite-LRU-walk-on-backup-failure/20260513-095356
base:   https://gitlab.freedesktop.org/drm/misc/kernel.git drm-misc-next
patch link:    https://lore.kernel.org/r/20260511162443.24352-1-thomas.hellstrom%40linux.intel.com
patch subject: [PATCH] drm/ttm: Fix ttm_bo_shrink() infinite LRU walk on backup failure
config: x86_64-allmodconfig (https://download.01.org/0day-ci/archive/20260513/202605131824.SbQ7agaE-lkp@intel.com/config)
compiler: clang version 20.1.8 (https://github.com/llvm/llvm-project 87f0227cb60147a26a1eeb4fb06e3b505e9c7261)
reproduce (this is a W=1 build): (https://download.01.org/0day-ci/archive/20260513/202605131824.SbQ7agaE-lkp@intel.com/reproduce)

If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <lkp@intel.com>
| Closes: https://lore.kernel.org/oe-kbuild-all/202605131824.SbQ7agaE-lkp@intel.com/

All errors (new ones prefixed by >>):

>> drivers/gpu/drm/ttm/ttm_bo_util.c:1121:3: error: call to undeclared function 'ttm_resource_del_bulk_move_unevictable'; ISO C99 and later do not support implicit function declarations [-Wimplicit-function-declaration]
    1121 |                 ttm_resource_del_bulk_move_unevictable(bo->resource, bo);
         |                 ^
   drivers/gpu/drm/ttm/ttm_bo_util.c:1121:3: note: did you mean 'ttm_resource_del_bulk_move'?
   include/drm/ttm/ttm_resource.h:449:6: note: 'ttm_resource_del_bulk_move' declared here
     449 | void ttm_resource_del_bulk_move(struct ttm_resource *res,
         |      ^
   1 error generated.


vim +/ttm_resource_del_bulk_move_unevictable +1121 drivers/gpu/drm/ttm/ttm_bo_util.c

  1067	
  1068	/**
  1069	 * ttm_bo_shrink() - Helper to shrink a ttm buffer object.
  1070	 * @ctx: The struct ttm_operation_ctx used for the shrinking operation.
  1071	 * @bo: The buffer object.
  1072	 * @flags: Flags governing the shrinking behaviour.
  1073	 *
  1074	 * The function uses the ttm_tt_back_up functionality to back up or
  1075	 * purge a struct ttm_tt. If the bo is not in system, it's first
  1076	 * moved there.
  1077	 *
  1078	 * Return: The number of pages shrunken or purged, or
  1079	 * negative error code on failure.
  1080	 */
  1081	long ttm_bo_shrink(struct ttm_operation_ctx *ctx, struct ttm_buffer_object *bo,
  1082			   const struct ttm_bo_shrink_flags flags)
  1083	{
  1084		static const struct ttm_place sys_placement_flags = {
  1085			.fpfn = 0,
  1086			.lpfn = 0,
  1087			.mem_type = TTM_PL_SYSTEM,
  1088			.flags = 0,
  1089		};
  1090		static struct ttm_placement sys_placement = {
  1091			.num_placement = 1,
  1092			.placement = &sys_placement_flags,
  1093		};
  1094		struct ttm_device *bdev = bo->bdev;
  1095		long lret;
  1096	
  1097		dma_resv_assert_held(bo->base.resv);
  1098	
  1099		if (flags.allow_move && bo->resource->mem_type != TTM_PL_SYSTEM) {
  1100			int ret = ttm_bo_validate(bo, &sys_placement, ctx);
  1101	
  1102			/* Consider -ENOMEM and -ENOSPC non-fatal. */
  1103			if (ret) {
  1104				if (ret == -ENOMEM || ret == -ENOSPC)
  1105					ret = -EBUSY;
  1106				return ret;
  1107			}
  1108		}
  1109	
  1110		ttm_bo_unmap_virtual(bo);
  1111		lret = ttm_bo_wait_ctx(bo, ctx);
  1112		if (lret < 0)
  1113			return lret;
  1114	
  1115		lret = ttm_tt_backup(bdev, bo->ttm, (struct ttm_backup_flags)
  1116				     {.purge = flags.purge,
  1117				      .writeback = flags.writeback});
  1118	
  1119		if (lret > 0) {
  1120			spin_lock(&bdev->lru_lock);
> 1121			ttm_resource_del_bulk_move_unevictable(bo->resource, bo);
  1122			ttm_resource_move_to_lru_tail(bo->resource);
  1123			spin_unlock(&bdev->lru_lock);
  1124		}
  1125	
  1126		if (lret < 0 && lret != -EINTR)
  1127			return -EBUSY;
  1128	
  1129		return lret;
  1130	}
  1131	EXPORT_SYMBOL(ttm_bo_shrink);
  1132	

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