drm/panfrost: Fix a race in panfrost_gem_free_object() (aed44cbe) · Commits · 戴 / test

panfrost_gem_shrinker_scan() might purge a BO (release the sgt and kill the GPU mapping) that's being freed by panfrost_gem_free_object() if we don't remove the BO from the shrinker list at the beginning of panfrost_gem_free_object(). Fixes: ("drm/panfrost: Add madvise and shrinker support") Cc: <stable@vger.kernel.org> Signed-off-by:

Boris Brezillon <boris.brezillon@collabora.com> Reviewed-by:

Steven Price <steven.price@arm.com> Acked-by:

Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com> Signed-off-by:

Rob Herring <robh@kernel.org> Link: https://patchwork.freedesktop.org/patch/msgid/20191129135908.2439529-5-boris.brezillon@collabora.com

drivers/gpu/drm/panfrost/panfrost_gem.c

+10 −5

Original line number	Diff line number	Diff line
		@@ -19,6 +19,16 @@ static void panfrost_gem_free_object(struct drm_gem_object *obj)
		struct panfrost_gem_object *bo = to_panfrost_bo(obj);
		struct panfrost_device *pfdev = obj->dev->dev_private;

		/*
		* Make sure the BO is no longer inserted in the shrinker list before
		* taking care of the destruction itself. If we don't do that we have a
		* race condition between this function and what's done in
		* panfrost_gem_shrinker_scan().
		*/
		mutex_lock(&pfdev->shrinker_lock);
		list_del_init(&bo->base.madv_list);
		mutex_unlock(&pfdev->shrinker_lock);

		if (bo->sgts) {
		int i;
		int n_sgt = bo->base.base.size / SZ_2M;
		@@ -33,11 +43,6 @@ static void panfrost_gem_free_object(struct drm_gem_object *obj)
		kfree(bo->sgts);
		}

		mutex_lock(&pfdev->shrinker_lock);
		if (!list_empty(&bo->base.madv_list))
		list_del(&bo->base.madv_list);
		mutex_unlock(&pfdev->shrinker_lock);

		drm_gem_shmem_free_object(obj);
		}

Admin message