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) v10: - Instead of using the existing helper, Wrap the interface inside out and provide a loop to de-midlayer things the LRU iteration (Christian König). - Removing the R-B by Matt Brost since the patch was significantly changed. Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx> --- drivers/gpu/drm/ttm/ttm_bo_util.c | 204 +++++++++++++++++++++++++++++- include/drm/ttm/ttm_bo.h | 88 +++++++++++++ 2 files changed, 288 insertions(+), 4 deletions(-) diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c index 454a51239614..b619cd7b3fab 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_util.c +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c @@ -769,12 +769,10 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo) return ret; } -static bool ttm_lru_walk_trylock(struct ttm_lru_walk *walk, +static bool ttm_lru_walk_trylock(struct ttm_operation_ctx *ctx, struct ttm_buffer_object *bo, bool *needs_unlock) { - struct ttm_operation_ctx *ctx = walk->ctx; - *needs_unlock = false; if (dma_resv_trylock(bo->base.resv)) { @@ -877,7 +875,7 @@ s64 ttm_lru_walk_for_evict(struct ttm_lru_walk *walk, struct ttm_device *bdev, * since if we do it the other way around, and the trylock fails, * we need to drop the lru lock to put the bo. */ - if (ttm_lru_walk_trylock(walk, bo, &bo_needs_unlock)) + if (ttm_lru_walk_trylock(walk->ctx, bo, &bo_needs_unlock)) bo_locked = true; else if (!walk->ticket || walk->ctx->no_wait_gpu || walk->trylock_only) @@ -920,3 +918,201 @@ 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. + * @ctx: The struct ttm_operation_ctx used for the shrinking operation. + * @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. + * + * Return: The number of pages shrunken or purged, or + * negative error code on failure. + */ +long ttm_bo_try_shrink(struct ttm_operation_ctx *ctx, 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_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); + +static void ttm_bo_lru_cursor_cleanup_bo(struct ttm_bo_lru_cursor *curs) +{ + struct ttm_buffer_object *bo = curs->bo; + + if (bo) { + if (curs->needs_unlock) + dma_resv_unlock(bo->base.resv); + ttm_bo_put(bo); + curs->bo = NULL; + } +} + +/** + * ttm_bo_lru_cursor_fini() - Stop using a struct ttm_bo_lru_cursor + * and clean up any iteration it was used for. + * @curs: The cursor. + */ +void ttm_bo_lru_cursor_fini(struct ttm_bo_lru_cursor *curs) +{ + spinlock_t *lru_lock = &curs->res_curs.man->bdev->lru_lock; + + ttm_bo_lru_cursor_cleanup_bo(curs); + spin_lock(lru_lock); + ttm_resource_cursor_fini(&curs->res_curs); + spin_unlock(lru_lock); +} +EXPORT_SYMBOL(ttm_bo_lru_cursor_fini); + +/** + * ttm_bo_lru_cursor_init() - Initialize a struct ttm_bo_lru_cursor + * @curs: The ttm_bo_lru_cursor to initialize. + * @man: The ttm resource_manager whose LRU lists to iterate over. + * @ctx: The ttm_operation_ctx to govern the locking. + * + * Initialize a struct ttm_bo_lru_cursor. Currently only trylocking + * or prelocked buffer objects are available as detailed by + * @ctx::resv and @ctx::allow_res_evict. Ticketlocking is not + * supported. + * + * Return: Pointer to @curs. The function does not fail. + */ +struct ttm_bo_lru_cursor * +ttm_bo_lru_cursor_init(struct ttm_bo_lru_cursor *curs, + struct ttm_resource_manager *man, + struct ttm_operation_ctx *ctx) +{ + memset(curs, 0, sizeof(*curs)); + ttm_resource_cursor_init(&curs->res_curs, man); + curs->ctx = ctx; + + return curs; +} +EXPORT_SYMBOL(ttm_bo_lru_cursor_init); + +static struct ttm_buffer_object * +ttm_bo_from_res_reserved(struct ttm_resource *res, struct ttm_bo_lru_cursor *curs) +{ + struct ttm_buffer_object *bo = res->bo; + + if (!ttm_lru_walk_trylock(curs->ctx, bo, &curs->needs_unlock)) + return NULL; + + if (!ttm_bo_get_unless_zero(bo)) { + if (curs->needs_unlock) + dma_resv_unlock(bo->base.resv); + return NULL; + } + + curs->bo = bo; + return bo; +} + +/** + * ttm_bo_lru_cursor_next() - Continue iterating a manager's LRU lists + * to find and lock buffer object. + * @curs: The cursor initialized using ttm_bo_lru_cursor_init() and + * ttm_bo_lru_cursor_first(). + * + * Return: A pointer to a locked and reference-counted buffer object, + * or NULL if none could be found and looping should be terminated. + */ +struct ttm_buffer_object *ttm_bo_lru_cursor_next(struct ttm_bo_lru_cursor *curs) +{ + spinlock_t *lru_lock = &curs->res_curs.man->bdev->lru_lock; + struct ttm_resource *res = NULL; + struct ttm_buffer_object *bo; + + ttm_bo_lru_cursor_cleanup_bo(curs); + + spin_lock(lru_lock); + for (;;) { + res = ttm_resource_manager_next(&curs->res_curs); + if (!res) + break; + + bo = ttm_bo_from_res_reserved(res, curs); + if (bo) + break; + } + + spin_unlock(lru_lock); + return res ? bo : NULL; +} +EXPORT_SYMBOL(ttm_bo_lru_cursor_next); + +/** + * ttm_bo_lru_cursor_first() - Start iterating a manager's LRU lists + * to find and lock buffer object. + * @curs: The cursor initialized using ttm_bo_lru_cursor_init(). + * + * Return: A pointer to a locked and reference-counted buffer object, + * or NULL if none could be found and looping should be terminated. + */ +struct ttm_buffer_object *ttm_bo_lru_cursor_first(struct ttm_bo_lru_cursor *curs) +{ + spinlock_t *lru_lock = &curs->res_curs.man->bdev->lru_lock; + struct ttm_buffer_object *bo; + struct ttm_resource *res; + + spin_lock(lru_lock); + res = ttm_resource_manager_first(&curs->res_curs); + if (!res) { + spin_unlock(lru_lock); + return NULL; + } + + bo = ttm_bo_from_res_reserved(res, curs); + spin_unlock(lru_lock); + + return bo ? bo : ttm_bo_lru_cursor_next(curs); +} +EXPORT_SYMBOL(ttm_bo_lru_cursor_first); diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h index 7b56d1ca36d7..48749c097f93 100644 --- a/include/drm/ttm/ttm_bo.h +++ b/include/drm/ttm/ttm_bo.h @@ -225,6 +225,23 @@ 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_operation_ctx *ctx, struct ttm_buffer_object *bo, + const struct ttm_bo_shrink_flags flags); + /** * ttm_bo_get - reference a struct ttm_buffer_object * @@ -463,4 +480,75 @@ pgprot_t ttm_io_prot(struct ttm_buffer_object *bo, struct ttm_resource *res, pgprot_t tmp); void ttm_bo_tt_destroy(struct ttm_buffer_object *bo); +/* Driver LRU walk helpers initially targeted for shrinking. */ + +/** + * struct ttm_bo_lru_cursor - Iterator cursor for TTM LRU list looping + */ +struct ttm_bo_lru_cursor { + /** @res_curs: Embedded struct ttm_resource_cursor. */ + struct ttm_resource_cursor res_curs; + /** + * @ctx: The struct ttm_operation_ctx used while looping. + * governs the locking mode. + */ + struct ttm_operation_ctx *ctx; + /** + * @bo: Buffer object pointer if a buffer object is refcounted, + * NULL otherwise. + */ + struct ttm_buffer_object *bo; + /** + * @needs_unlock: Valid iff @bo != NULL. The bo resv needs + * unlock before the next iteration or after loop exit. + */ + bool needs_unlock; +}; + +void ttm_bo_lru_cursor_fini(struct ttm_bo_lru_cursor *curs); + +struct ttm_bo_lru_cursor * +ttm_bo_lru_cursor_init(struct ttm_bo_lru_cursor *curs, + struct ttm_resource_manager *man, + struct ttm_operation_ctx *ctx); + +struct ttm_buffer_object *ttm_bo_lru_cursor_first(struct ttm_bo_lru_cursor *curs); + +struct ttm_buffer_object *ttm_bo_lru_cursor_next(struct ttm_bo_lru_cursor *curs); + +/* + * Defines needed to use autocleanup (linux/cleanup.h) with struct ttm_bo_lru_cursor. + */ +DEFINE_CLASS(ttm_bo_lru_cursor, struct ttm_bo_lru_cursor *, + if (_T) {ttm_bo_lru_cursor_fini(_T); }, + ttm_bo_lru_cursor_init(curs, man, ctx), + struct ttm_bo_lru_cursor *curs, struct ttm_resource_manager *man, + struct ttm_operation_ctx *ctx); +static inline void * +class_ttm_bo_lru_cursor_lock_ptr(class_ttm_bo_lru_cursor_t *_T) +{ return *_T; } + +/** + * ttm_bo_lru_for_each_reserved_guarded() - Iterate over buffer objects owning + * resources on LRU lists. + * @_cursor: struct ttm_bo_lru_cursor to use for the iteration. + * @_man: The resource manager whose LRU lists to iterate over. + * @_ctx: The struct ttm_operation_context to govern the @_bo locking. + * @_bo: The struct ttm_buffer_object pointer pointing to the buffer object + * for the current iteration. + * + * Iterate over all resources of @_man and for each resource, attempt to + * reference and lock (using the locking mode detailed in @_ctx) the buffer + * object it points to. If successful, assign @_bo to the address of the + * buffer object and update @_cursor. The iteration is guarded in the + * sense that @_cursor will be initialized before looping start and cleaned + * up at looping termination, even if terminated prematurely by, for + * example a return or break statement. Exiting the loop will also unlock + * (if needed) and unreference @_bo. + */ +#define ttm_bo_lru_for_each_reserved_guarded(_cursor, _man, _ctx, _bo) \ + scoped_guard(ttm_bo_lru_cursor, _cursor, _man, _ctx) \ + for ((_bo) = ttm_bo_lru_cursor_first(_cursor); (_bo); \ + (_bo) = ttm_bo_lru_cursor_next(_cursor)) + #endif -- 2.46.0
