| Message ID | 20230903170736.513347-6-dmitry.osipenko@collabora.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Add generic memory shrinker to VirtIO-GPU and Panfrost DRM drivers | expand |
On Sun, 3 Sep 2023 20:07:21 +0300 Dmitry Osipenko <dmitry.osipenko@collabora.com> wrote: > The drm_gem_shmem_free() doesn't put GEM's kref to zero, which becomes > important with addition of the shrinker support to drm-shmem that will > use kref=0 in order to prevent taking lock during special GEM-freeing > time in order to avoid spurious lockdep warning about locking ordering > vs fs_reclaim code paths. As for patch 4, I don't mind the change (I actually think it's better to have a single error path with a free function handling partially initialized GEM objects, which is exactly what your patch is doing), but I disagree with the explanation, especially after you dropped "drm/shmem-helper: Add and use drm_gem_shmem_resv_assert_held() helper" and went for a drm_gem_shmem_do_release_pages_locked() helper called in drm_gem_shmem_free(). > > Replace open-coded drm_gem_shmem_free() with drm_gem_object_put() that > drops kref to zero before freeing GEM. > > Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> > --- > drivers/gpu/drm/v3d/v3d_bo.c | 22 ++++++++++++---------- > 1 file changed, 12 insertions(+), 10 deletions(-) > > diff --git a/drivers/gpu/drm/v3d/v3d_bo.c b/drivers/gpu/drm/v3d/v3d_bo.c > index 8b3229a37c6d..70c1095d6eec 100644 > --- a/drivers/gpu/drm/v3d/v3d_bo.c > +++ b/drivers/gpu/drm/v3d/v3d_bo.c > @@ -33,16 +33,18 @@ void v3d_free_object(struct drm_gem_object *obj) > struct v3d_dev *v3d = to_v3d_dev(obj->dev); > struct v3d_bo *bo = to_v3d_bo(obj); > > - v3d_mmu_remove_ptes(bo); > + if (drm_mm_node_allocated(&bo->node)) { > + v3d_mmu_remove_ptes(bo); > > - mutex_lock(&v3d->bo_lock); > - v3d->bo_stats.num_allocated--; > - v3d->bo_stats.pages_allocated -= obj->size >> PAGE_SHIFT; > - mutex_unlock(&v3d->bo_lock); > + mutex_lock(&v3d->bo_lock); > + v3d->bo_stats.num_allocated--; > + v3d->bo_stats.pages_allocated -= obj->size >> PAGE_SHIFT; > + mutex_unlock(&v3d->bo_lock); > > - spin_lock(&v3d->mm_lock); > - drm_mm_remove_node(&bo->node); > - spin_unlock(&v3d->mm_lock); > + spin_lock(&v3d->mm_lock); > + drm_mm_remove_node(&bo->node); > + spin_unlock(&v3d->mm_lock); > + } > > /* GPU execution may have dirtied any pages in the BO. */ > bo->base.pages_mark_dirty_on_put = true; > @@ -142,7 +144,7 @@ struct v3d_bo *v3d_bo_create(struct drm_device *dev, struct drm_file *file_priv, > return bo; > > free_obj: > - drm_gem_shmem_free(shmem_obj); > + drm_gem_object_put(&shmem_obj->base); > return ERR_PTR(ret); > } > > @@ -160,7 +162,7 @@ v3d_prime_import_sg_table(struct drm_device *dev, > > ret = v3d_bo_create_finish(obj); > if (ret) { > - drm_gem_shmem_free(&to_v3d_bo(obj)->base); > + drm_gem_object_put(obj); > return ERR_PTR(ret); > } >
diff --git a/drivers/gpu/drm/v3d/v3d_bo.c b/drivers/gpu/drm/v3d/v3d_bo.c index 8b3229a37c6d..70c1095d6eec 100644 --- a/drivers/gpu/drm/v3d/v3d_bo.c +++ b/drivers/gpu/drm/v3d/v3d_bo.c @@ -33,16 +33,18 @@ void v3d_free_object(struct drm_gem_object *obj) struct v3d_dev *v3d = to_v3d_dev(obj->dev); struct v3d_bo *bo = to_v3d_bo(obj); - v3d_mmu_remove_ptes(bo); + if (drm_mm_node_allocated(&bo->node)) { + v3d_mmu_remove_ptes(bo); - mutex_lock(&v3d->bo_lock); - v3d->bo_stats.num_allocated--; - v3d->bo_stats.pages_allocated -= obj->size >> PAGE_SHIFT; - mutex_unlock(&v3d->bo_lock); + mutex_lock(&v3d->bo_lock); + v3d->bo_stats.num_allocated--; + v3d->bo_stats.pages_allocated -= obj->size >> PAGE_SHIFT; + mutex_unlock(&v3d->bo_lock); - spin_lock(&v3d->mm_lock); - drm_mm_remove_node(&bo->node); - spin_unlock(&v3d->mm_lock); + spin_lock(&v3d->mm_lock); + drm_mm_remove_node(&bo->node); + spin_unlock(&v3d->mm_lock); + } /* GPU execution may have dirtied any pages in the BO. */ bo->base.pages_mark_dirty_on_put = true; @@ -142,7 +144,7 @@ struct v3d_bo *v3d_bo_create(struct drm_device *dev, struct drm_file *file_priv, return bo; free_obj: - drm_gem_shmem_free(shmem_obj); + drm_gem_object_put(&shmem_obj->base); return ERR_PTR(ret); } @@ -160,7 +162,7 @@ v3d_prime_import_sg_table(struct drm_device *dev, ret = v3d_bo_create_finish(obj); if (ret) { - drm_gem_shmem_free(&to_v3d_bo(obj)->base); + drm_gem_object_put(obj); return ERR_PTR(ret); }
The drm_gem_shmem_free() doesn't put GEM's kref to zero, which becomes important with addition of the shrinker support to drm-shmem that will use kref=0 in order to prevent taking lock during special GEM-freeing time in order to avoid spurious lockdep warning about locking ordering vs fs_reclaim code paths. Replace open-coded drm_gem_shmem_free() with drm_gem_object_put() that drops kref to zero before freeing GEM. Signed-off-by: Dmitry Osipenko <dmitry.osipenko@collabora.com> --- drivers/gpu/drm/v3d/v3d_bo.c | 22 ++++++++++++---------- 1 file changed, 12 insertions(+), 10 deletions(-)