From: Dmitry Osipenko <dmitry.osipenko@collabora.com> To: "David Airlie" <airlied@gmail.com>, "Gerd Hoffmann" <kraxel@redhat.com>, "Gurchetan Singh" <gurchetansingh@chromium.org>, "Chia-I Wu" <olvaffe@gmail.com>, "Daniel Vetter" <daniel@ffwll.ch>, "Daniel Almeida" <daniel.almeida@collabora.com>, "Gustavo Padovan" <gustavo.padovan@collabora.com>, "Daniel Stone" <daniel@fooishbar.org>, "Tomeu Vizoso" <tomeu.vizoso@collabora.com>, "Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>, "Maxime Ripard" <mripard@kernel.org>, "Thomas Zimmermann" <tzimmermann@suse.de>, "Rob Clark" <robdclark@gmail.com>, "Sumit Semwal" <sumit.semwal@linaro.org>, "Christian König" <christian.koenig@amd.com>, "Qiang Yu" <yuq825@gmail.com>, "Steven Price" <steven.price@arm.com>, "Alyssa Rosenzweig" <alyssa.rosenzweig@collabora.com>, "Rob Herring" <robh@kernel.org>, "Sean Paul" <sean@poorly.run>, "Dmitry Baryshkov" <dmitry.baryshkov@linaro.org>, "Abhinav Kumar" <quic_abhinavk@quicinc.com> Cc: dri-devel@lists.freedesktop.org, linux-kernel@vger.kernel.org, kernel@collabora.com, virtualization@lists.linux-foundation.org Subject: [PATCH v9 01/11] drm/msm/gem: Prevent blocking within shrinker loop Date: Wed, 23 Nov 2022 05:57:13 +0300 [thread overview] Message-ID: <20221123025723.695075-2-dmitry.osipenko@collabora.com> (raw) In-Reply-To: <20221123025723.695075-1-dmitry.osipenko@collabora.com> Consider this scenario: 1. APP1 continuously creates lots of small GEMs 2. APP2 triggers `drop_caches` 3. Shrinker starts to evict APP1 GEMs, while APP1 produces new purgeable GEMs 4. msm_gem_shrinker_scan() returns non-zero number of freed pages and causes shrinker to try shrink more 5. msm_gem_shrinker_scan() returns non-zero number of freed pages again, goto 4 6. The APP2 is blocked in `drop_caches` until APP1 stops producing purgeable GEMs To prevent this blocking scenario, check number of remaining pages that GPU shrinker couldn't release due to a GEM locking contention or shrinking rejection. If there are no remaining pages left to shrink, then there is no need to free up more pages and shrinker may break out from the loop. This problem was found during shrinker/madvise IOCTL testing of virtio-gpu driver. The MSM driver is affected in the same way. Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> --- drivers/gpu/drm/drm_gem.c | 9 +++++++-- drivers/gpu/drm/msm/msm_gem_shrinker.c | 8 ++++++-- include/drm/drm_gem.h | 4 +++- 3 files changed, 16 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index b8db675e7fb5..299bca1390aa 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -1375,10 +1375,13 @@ EXPORT_SYMBOL(drm_gem_lru_move_tail); * * @lru: The LRU to scan * @nr_to_scan: The number of pages to try to reclaim + * @remaining: The number of pages left to reclaim * @shrink: Callback to try to shrink/reclaim the object. */ unsigned long -drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan, +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 drm_gem_lru still_in_lru; @@ -1417,8 +1420,10 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan, * 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 (!dma_resv_trylock(obj->resv)) { + *remaining += obj->size >> PAGE_SHIFT; goto tail; + } if (shrink(obj)) { freed += obj->size >> PAGE_SHIFT; diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c index 1de14e67f96b..4c8b0ab61ce4 100644 --- a/drivers/gpu/drm/msm/msm_gem_shrinker.c +++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c @@ -116,12 +116,14 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) }; long nr = sc->nr_to_scan; unsigned long freed = 0; + unsigned long remaining = 0; for (unsigned i = 0; (nr > 0) && (i < ARRAY_SIZE(stages)); i++) { if (!stages[i].cond) continue; stages[i].freed = - drm_gem_lru_scan(stages[i].lru, nr, stages[i].shrink); + drm_gem_lru_scan(stages[i].lru, nr, &remaining, + stages[i].shrink); nr -= stages[i].freed; freed += stages[i].freed; } @@ -132,7 +134,7 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) stages[3].freed); } - return (freed > 0) ? freed : SHRINK_STOP; + return (freed > 0 && remaining > 0) ? freed : SHRINK_STOP; } #ifdef CONFIG_DEBUG_FS @@ -182,10 +184,12 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr) NULL, }; unsigned idx, unmapped = 0; + unsigned long remaining = 0; for (idx = 0; lrus[idx] && unmapped < vmap_shrink_limit; idx++) { unmapped += drm_gem_lru_scan(lrus[idx], vmap_shrink_limit - unmapped, + &remaining, vmap_shrink); } diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index a17c2f903f81..b46ade812443 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -475,7 +475,9 @@ int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev, 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(struct drm_gem_lru *lru, struct drm_gem_object *obj); -unsigned long drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan, +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)); #endif /* __DRM_GEM_H__ */ -- 2.38.1
WARNING: multiple messages have this Message-ID (diff)
From: Dmitry Osipenko <dmitry.osipenko@collabora.com> To: "David Airlie" <airlied@gmail.com>, "Gerd Hoffmann" <kraxel@redhat.com>, "Gurchetan Singh" <gurchetansingh@chromium.org>, "Chia-I Wu" <olvaffe@gmail.com>, "Daniel Vetter" <daniel@ffwll.ch>, "Daniel Almeida" <daniel.almeida@collabora.com>, "Gustavo Padovan" <gustavo.padovan@collabora.com>, "Daniel Stone" <daniel@fooishbar.org>, "Tomeu Vizoso" <tomeu.vizoso@collabora.com>, "Maarten Lankhorst" <maarten.lankhorst@linux.intel.com>, "Maxime Ripard" <mripard@kernel.org>, "Thomas Zimmermann" <tzimmermann@suse.de>, "Rob Clark" <robdclark@gmail.com>, "Sumit Semwal" <sumit.semwal@linaro.org>, "Christian König" <christian.koenig@amd.com>, "Qiang Yu" <yuq825@gmail.com>, "Steven Price" <steven.price@arm.com>, "Alyssa Rosenzweig" <alyssa.rosenzweig@collabora.com>, "Rob Herring" <robh@kernel.org>, "Sean Paul" <sean@poorly.run>, "Dmitry Baryshkov" <dmitry.baryshkov@linaro.org>, "Abhinav Kumar" <quic_abhinavk@quicinc.com> Cc: kernel@collabora.com, linux-kernel@vger.kernel.org, dri-devel@lists.freedesktop.org, virtualization@lists.linux-foundation.org Subject: [PATCH v9 01/11] drm/msm/gem: Prevent blocking within shrinker loop Date: Wed, 23 Nov 2022 05:57:13 +0300 [thread overview] Message-ID: <20221123025723.695075-2-dmitry.osipenko@collabora.com> (raw) In-Reply-To: <20221123025723.695075-1-dmitry.osipenko@collabora.com> Consider this scenario: 1. APP1 continuously creates lots of small GEMs 2. APP2 triggers `drop_caches` 3. Shrinker starts to evict APP1 GEMs, while APP1 produces new purgeable GEMs 4. msm_gem_shrinker_scan() returns non-zero number of freed pages and causes shrinker to try shrink more 5. msm_gem_shrinker_scan() returns non-zero number of freed pages again, goto 4 6. The APP2 is blocked in `drop_caches` until APP1 stops producing purgeable GEMs To prevent this blocking scenario, check number of remaining pages that GPU shrinker couldn't release due to a GEM locking contention or shrinking rejection. If there are no remaining pages left to shrink, then there is no need to free up more pages and shrinker may break out from the loop. This problem was found during shrinker/madvise IOCTL testing of virtio-gpu driver. The MSM driver is affected in the same way. Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> --- drivers/gpu/drm/drm_gem.c | 9 +++++++-- drivers/gpu/drm/msm/msm_gem_shrinker.c | 8 ++++++-- include/drm/drm_gem.h | 4 +++- 3 files changed, 16 insertions(+), 5 deletions(-) diff --git a/drivers/gpu/drm/drm_gem.c b/drivers/gpu/drm/drm_gem.c index b8db675e7fb5..299bca1390aa 100644 --- a/drivers/gpu/drm/drm_gem.c +++ b/drivers/gpu/drm/drm_gem.c @@ -1375,10 +1375,13 @@ EXPORT_SYMBOL(drm_gem_lru_move_tail); * * @lru: The LRU to scan * @nr_to_scan: The number of pages to try to reclaim + * @remaining: The number of pages left to reclaim * @shrink: Callback to try to shrink/reclaim the object. */ unsigned long -drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan, +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 drm_gem_lru still_in_lru; @@ -1417,8 +1420,10 @@ drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan, * 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 (!dma_resv_trylock(obj->resv)) { + *remaining += obj->size >> PAGE_SHIFT; goto tail; + } if (shrink(obj)) { freed += obj->size >> PAGE_SHIFT; diff --git a/drivers/gpu/drm/msm/msm_gem_shrinker.c b/drivers/gpu/drm/msm/msm_gem_shrinker.c index 1de14e67f96b..4c8b0ab61ce4 100644 --- a/drivers/gpu/drm/msm/msm_gem_shrinker.c +++ b/drivers/gpu/drm/msm/msm_gem_shrinker.c @@ -116,12 +116,14 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) }; long nr = sc->nr_to_scan; unsigned long freed = 0; + unsigned long remaining = 0; for (unsigned i = 0; (nr > 0) && (i < ARRAY_SIZE(stages)); i++) { if (!stages[i].cond) continue; stages[i].freed = - drm_gem_lru_scan(stages[i].lru, nr, stages[i].shrink); + drm_gem_lru_scan(stages[i].lru, nr, &remaining, + stages[i].shrink); nr -= stages[i].freed; freed += stages[i].freed; } @@ -132,7 +134,7 @@ msm_gem_shrinker_scan(struct shrinker *shrinker, struct shrink_control *sc) stages[3].freed); } - return (freed > 0) ? freed : SHRINK_STOP; + return (freed > 0 && remaining > 0) ? freed : SHRINK_STOP; } #ifdef CONFIG_DEBUG_FS @@ -182,10 +184,12 @@ msm_gem_shrinker_vmap(struct notifier_block *nb, unsigned long event, void *ptr) NULL, }; unsigned idx, unmapped = 0; + unsigned long remaining = 0; for (idx = 0; lrus[idx] && unmapped < vmap_shrink_limit; idx++) { unmapped += drm_gem_lru_scan(lrus[idx], vmap_shrink_limit - unmapped, + &remaining, vmap_shrink); } diff --git a/include/drm/drm_gem.h b/include/drm/drm_gem.h index a17c2f903f81..b46ade812443 100644 --- a/include/drm/drm_gem.h +++ b/include/drm/drm_gem.h @@ -475,7 +475,9 @@ int drm_gem_dumb_map_offset(struct drm_file *file, struct drm_device *dev, 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(struct drm_gem_lru *lru, struct drm_gem_object *obj); -unsigned long drm_gem_lru_scan(struct drm_gem_lru *lru, unsigned nr_to_scan, +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)); #endif /* __DRM_GEM_H__ */ -- 2.38.1
next prev parent reply other threads:[~2022-11-23 3:00 UTC|newest] Thread overview: 37+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-11-23 2:57 [PATCH v9 00/11] Add generic memory shrinker to VirtIO-GPU and Panfrost DRM drivers Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko [this message] 2022-11-23 2:57 ` [PATCH v9 01/11] drm/msm/gem: Prevent blocking within shrinker loop Dmitry Osipenko 2022-11-29 16:40 ` Rob Clark 2022-11-29 16:40 ` Rob Clark 2022-11-29 16:40 ` Rob Clark 2022-11-23 2:57 ` [PATCH v9 02/11] drm/panfrost: Don't sync rpm suspension after mmu flushing Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 15:59 ` Steven Price 2022-11-23 2:57 ` [PATCH v9 03/11] drm/gem: Add evict() callback to drm_gem_object_funcs Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 15:58 ` Steven Price 2022-11-23 16:40 ` Dmitry Osipenko 2022-11-23 2:57 ` [PATCH v9 04/11] drm/shmem: Put booleans in the end of struct drm_gem_shmem_object Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 2:57 ` [PATCH v9 05/11] drm/shmem: Switch to use drm_* debug helpers Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 2:57 ` [PATCH v9 06/11] drm/shmem-helper: Don't use vmap_use_count for dma-bufs Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 2:57 ` [PATCH v9 07/11] drm/shmem-helper: Switch to reservation lock Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 2:57 ` [PATCH v9 08/11] drm/shmem-helper: Add memory shrinker Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 15:56 ` kernel test robot 2022-11-23 15:56 ` kernel test robot 2022-11-23 15:56 ` kernel test robot 2022-11-23 18:08 ` kernel test robot 2022-11-23 18:08 ` kernel test robot 2022-11-23 18:08 ` kernel test robot 2022-11-23 2:57 ` [PATCH v9 09/11] drm/gem: Add drm_gem_pin_unlocked() Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 2:57 ` [PATCH v9 10/11] drm/virtio: Support memory shrinking Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 2:57 ` [PATCH v9 11/11] drm/panfrost: Switch to generic memory shrinker Dmitry Osipenko 2022-11-23 2:57 ` Dmitry Osipenko 2022-11-23 17:03 ` Steven Price
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