Following the design direction communicated here: https://lore.kernel.org/linux-mm/b7491378-defd-4f1c-31e2-29e4c77e2d67@xxxxxxx/T/#ma918844aa8a6efe8768fdcda0c6590d5c93850c9 Export the LRU walker for driver shrinker use and add a bo shrinker helper for initial use by the xe driver. v8: - Split out from another patch. - Use a struct for bool arguments to increase readability (Matt Brost). - Unmap user-space cpu-mappings before shrinking pages. - Explain non-fatal error codes (Matt Brost) Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/ttm/ttm_bo_util.c | 65 +++++++++++++++++++++++++++++++ include/drm/ttm/ttm_bo.h | 17 ++++++++ 2 files changed, 82 insertions(+) diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c index 3c07f4712d5c..3490e3347de9 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_util.c +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c @@ -919,3 +919,68 @@ s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct ttm_device *bdev, return progress; } +EXPORT_SYMBOL(ttm_lru_walk_for_evict); + +/** + * ttm_bo_try_shrink - LRU walk helper to shrink a ttm buffer object. + * @walk: The struct xe_ttm_lru_walk that describes the walk. + * @bo: The buffer object. + * @flags: Flags governing the shrinking behaviour. + * + * The function uses the ttm_tt_back_up functionality to back up or + * purge a struct ttm_tt. If the bo is not in system, it's first + * moved there, unless @flags.allow_move is false. + * + * Return: The number of pages shrunken or purged, or + * negative error code on failure. + */ +long ttm_bo_try_shrink(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo, + const struct ttm_bo_shrink_flags flags) +{ + static const struct ttm_place sys_placement_flags = { + .fpfn = 0, + .lpfn = 0, + .mem_type = TTM_PL_SYSTEM, + .flags = 0, + }; + static struct ttm_placement sys_placement = { + .num_placement = 1, + .placement = &sys_placement_flags, + }; + struct ttm_operation_ctx *ctx = walk->ctx; + struct ttm_tt *tt = bo->ttm; + long lret; + + dma_resv_assert_held(bo->base.resv); + + if (!tt || !ttm_tt_is_populated(tt)) + return 0; + + if (flags.allow_move && bo->resource->mem_type != TTM_PL_SYSTEM) { + int ret = ttm_bo_validate(bo, &sys_placement, ctx); + + /* Consider -ENOMEM and -ENOSPC non-fatal. */ + if (ret) { + if (ret == -ENOMEM || ret == -ENOSPC) + ret = -EBUSY; + return ret; + } + } + + ttm_bo_unmap_virtual(bo); + lret = ttm_bo_wait_ctx(bo, ctx); + if (lret < 0) { + if (lret == -ERESTARTSYS) + return lret; + return 0; + } + + lret = ttm_tt_backup(bo->bdev, tt, (struct ttm_backup_flags) + {.purge = flags.purge, + .writeback = flags.writeback}); + if (lret < 0 && lret != -EINTR) + return 0; + + return lret; +} +EXPORT_SYMBOL(ttm_bo_try_shrink); diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h index d1a732d56259..479ada85cea1 100644 --- a/include/drm/ttm/ttm_bo.h +++ b/include/drm/ttm/ttm_bo.h @@ -229,6 +229,23 @@ struct ttm_lru_walk { s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct ttm_device *bdev, struct ttm_resource_manager *man, s64 target); +/** + * struct ttm_bo_shrink_flags - flags to govern the bo shrinking behaviour + * @purge: Purge the content rather than backing it up. + * @writeback: Attempt to immediately write content to swap space. + * @allow_move: Allow moving to system before shrinking. This is typically + * not desired for zombie- or ghost objects (with zombie object meaning + * objects with a zero gem object refcount) + */ +struct ttm_bo_shrink_flags { + u32 purge : 1; + u32 writeback : 1; + u32 allow_move : 1; +}; + +long ttm_bo_try_shrink(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo, + const struct ttm_bo_shrink_flags flags); + /** * ttm_bo_get - reference a struct ttm_buffer_object * -- 2.44.0
