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Wed, 14 May 2025 10:03:20 -0700 (PDT) From: Rob Clark To: dri-devel@lists.freedesktop.org Cc: freedreno@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, Connor Abbott , Rob Clark , Maarten Lankhorst , Maxime Ripard , Thomas Zimmermann , David Airlie , Simona Vetter , Rob Clark , Abhinav Kumar , Dmitry Baryshkov , Sean Paul , Marijn Suijten , linux-kernel@vger.kernel.org (open list) Subject: [PATCH v4 03/40] drm/gem: Add ww_acquire_ctx support to drm_gem_lru_scan() Date: Wed, 14 May 2025 09:59:02 -0700 Message-ID: <20250514170118.40555-4-robdclark@gmail.com> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20250514170118.40555-1-robdclark@gmail.com> References: <20250514170118.40555-1-robdclark@gmail.com> Precedence: bulk X-Mailing-List: linux-arm-msm@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 From: Rob Clark If the callback is going to have to attempt to grab more locks, it is useful to have an ww_acquire_ctx to avoid locking order problems. Why not use the drm_exec helper instead? Mainly because (a) where ww_acquire_init() is called is awkward, and (b) we don't really need to retry after backoff, we can just move on to the next object. Signed-off-by: Rob Clark --- drivers/gpu/drm/drm_gem.c | 14 +++++++++++--- drivers/gpu/drm/msm/msm_gem_shrinker.c | 24 +++++++++++++----------- include/drm/drm_gem.h | 10 ++++++---- 3 files changed, 30 insertions(+), 18 deletions(-) diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index ee811764c3df..9e3db9a864f8 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -1460,12 +1460,14 @@ EXPORT_SYMBOL(drm_gem_lru_move_tail); * @nr_to_scan: The number of pages to try to reclaim * @remaining: The number of pages left to reclaim, should be initialized by caller * @shrink: Callback to try to shrink/reclaim the object. + * @ticket: Optional ww_acquire_ctx context to use for locking */ unsigned long drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned int nr_to_scan, unsigned long *remaining, - bool (*shrink)(struct drm_gem_object *obj)) + bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket), + struct ww_acquire_ctx *ticket) { struct drm_gem_lru still_in_lru; struct drm_gem_object *obj; @@ -1498,17 +1500,20 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, */ mutex_unlock(lru->lock); + if (ticket) + ww_acquire_init(ticket, &reservation_ww_class); + /* * Note that this still needs to be trylock, since we can * hit shrinker in response to trying to get backing pages * for this obj (ie. while it's lock is already held) */ - if (!dma_resv_trylock(obj->resv)) { + if (!ww_mutex_trylock(&obj->resv->lock, ticket)) { *remaining += obj->size >> PAGE_SHIFT; goto tail; } - if (shrink(obj)) { + if (shrink(obj, ticket)) { freed += obj->size >> PAGE_SHIFT; /* @@ -1522,6 +1527,9 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, dma_resv_unlock(obj->resv); + if (ticket) + ww_acquire_fini(ticket); + tail: drm_gem_object_put(obj); mutex_lock(lru->lock); diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c index 07ca4ddfe4e3..de185fc34084 100644 --- a/drivers/gpu/drm/msm/msm_gem_shrinker.c +++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c @@ -44,7 +44,7 @@ msm_gem_shrinker_count(struct shrinker *shrinker, struct shrink_control *sc) } static bool -purge(struct drm_gem_object *obj) +purge(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket) { if (!is_purgeable(to_msm_bo(obj))) return false; @@ -58,7 +58,7 @@ purge(struct drm_gem_object *obj) } static bool -evict(struct drm_gem_object *obj) +evict(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket) { if (is_unevictable(to_msm_bo(obj))) return false; @@ -79,21 +79,21 @@ wait_for_idle(struct drm_gem_object *obj) } static bool -active_purge(struct drm_gem_object *obj) +active_purge(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket) { if (!wait_for_idle(obj)) return false; - return purge(obj); + return purge(obj, ticket); } static bool -active_evict(struct drm_gem_object *obj) +active_evict(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket) { if (!wait_for_idle(obj)) return false; - return evict(obj); + return evict(obj, ticket); } static unsigned long @@ -102,7 +102,7 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) struct msm_drm_private *priv = shrinker->private_data; struct { struct drm_gem_lru *lru; - bool (*shrink)(struct drm_gem_object *obj); + bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket); bool cond; unsigned long freed; unsigned long remaining; @@ -122,8 +122,9 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) continue; stages[i].freed = drm_gem_lru_scan(stages[i].lru, nr, - &stages[i].remaining, - stages[i].shrink); + &stages[i].remaining, + stages[i].shrink, + NULL); nr -= stages[i].freed; freed += stages[i].freed; remaining += stages[i].remaining; @@ -164,7 +165,7 @@ msm_gem_shrinker_shrink(struct drm_device *dev, unsigned long nr_to_scan) static const int vmap_shrink_limit = 15; static bool -vmap_shrink(struct drm_gem_object *obj) +vmap_shrink(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket) { if (!is_vunmapable(to_msm_bo(obj))) return false; @@ -192,7 +193,8 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr) unmapped += drm_gem_lru_scan(lrus[idx], vmap_shrink_limit - unmapped, &remaining, - vmap_shrink); + vmap_shrink, + NULL); } *(unsigned long *)ptr += unmapped; diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index fdae947682cd..0e2c476df731 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -555,10 +555,12 @@ void drm_gem_lru_init(struct drm_gem_lru *lru, struct mutex *lock); void drm_gem_lru_remove(struct drm_gem_object *obj); void drm_gem_lru_move_tail_locked(struct drm_gem_lru *lru, struct drm_gem_object *obj); void drm_gem_lru_move_tail(struct drm_gem_lru *lru, struct drm_gem_object *obj); -unsigned long drm_gem_lru_scan(struct drm_gem_lru *lru, - unsigned int nr_to_scan, - unsigned long *remaining, - bool (*shrink)(struct drm_gem_object *obj)); +unsigned long +drm_gem_lru_scan(struct drm_gem_lru *lru, + unsigned int nr_to_scan, + unsigned long *remaining, + bool (*shrink)(struct drm_gem_object *obj, struct ww_acquire_ctx *ticket), + struct ww_acquire_ctx *ticket); int drm_gem_evict(struct drm_gem_object *obj);