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From: Robin Murphy <robin.murphy@arm.com>
To: Boris Brezillon <boris.brezillon@collabora.com>,
	Rob Herring <robh+dt@kernel.org>,
	Tomeu Vizoso <tomeu@tomeuvizoso.net>,
	Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
	Steven Price <steven.price@arm.com>
Cc: stable@vger.kernel.org, dri-devel@lists.freedesktop.org
Subject: Re: [PATCH 8/8] drm/panfrost: Make sure the shrinker does not reclaim referenced BOs
Date: Mon, 2 Dec 2019 12:50:20 +0000	[thread overview]
Message-ID: <7258aca4-115d-d511-4c0a-fb3ba142f382@arm.com> (raw)
In-Reply-To: <20191129135908.2439529-9-boris.brezillon@collabora.com>

On 29/11/2019 1:59 pm, Boris Brezillon wrote:
> Userspace might tag a BO purgeable while it's still referenced by GPU
> jobs. We need to make sure the shrinker does not purge such BOs until
> all jobs referencing it are finished.

Nit: for extra robustness, perhaps it's worth using the refcount_t API 
rather than bare atomic_t?

Robin.

> Fixes: 013b65101315 ("drm/panfrost: Add madvise and shrinker support")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> ---
>   drivers/gpu/drm/panfrost/panfrost_drv.c          | 1 +
>   drivers/gpu/drm/panfrost/panfrost_gem.h          | 6 ++++++
>   drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c | 2 ++
>   drivers/gpu/drm/panfrost/panfrost_job.c          | 7 ++++++-
>   4 files changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index b406b5243b40..297c0e7304d2 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -166,6 +166,7 @@ panfrost_lookup_bos(struct drm_device *dev,
>   			break;
>   		}
>   
> +		atomic_inc(&bo->gpu_usecount);
>   		job->mappings[i] = mapping;
>   	}
>   
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
> index ca1bc9019600..b3517ff9630c 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
> @@ -30,6 +30,12 @@ struct panfrost_gem_object {
>   		struct mutex lock;
>   	} mappings;
>   
> +	/*
> +	 * Count the number of jobs referencing this BO so we don't let the
> +	 * shrinker reclaim this object prematurely.
> +	 */
> +	atomic_t gpu_usecount;
> +
>   	bool noexec		:1;
>   	bool is_heap		:1;
>   };
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> index b36df326c860..288e46c40673 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> @@ -41,6 +41,8 @@ static bool panfrost_gem_purge(struct drm_gem_object *obj)
>   	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>   	struct panfrost_gem_object *bo = to_panfrost_bo(obj);
>   
> +	if (atomic_read(&bo->gpu_usecount))
> +		return false;
>   
>   	if (!mutex_trylock(&shmem->pages_lock))
>   		return false;
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index c85d45be3b5e..2b12aa87ff32 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -270,8 +270,13 @@ static void panfrost_job_cleanup(struct kref *ref)
>   	dma_fence_put(job->render_done_fence);
>   
>   	if (job->mappings) {
> -		for (i = 0; i < job->bo_count; i++)
> +		for (i = 0; i < job->bo_count; i++) {
> +			if (!job->mappings[i])
> +				break;
> +
> +			atomic_dec(&job->mappings[i]->obj->gpu_usecount);
>   			panfrost_gem_mapping_put(job->mappings[i]);
> +		}
>   		kvfree(job->mappings);
>   	}
>   
> 

WARNING: multiple messages have this Message-ID (diff)
From: Robin Murphy <robin.murphy@arm.com>
To: Boris Brezillon <boris.brezillon@collabora.com>,
	Rob Herring <robh+dt@kernel.org>,
	Tomeu Vizoso <tomeu@tomeuvizoso.net>,
	Alyssa Rosenzweig <alyssa.rosenzweig@collabora.com>,
	Steven Price <steven.price@arm.com>
Cc: dri-devel@lists.freedesktop.org, stable@vger.kernel.org
Subject: Re: [PATCH 8/8] drm/panfrost: Make sure the shrinker does not reclaim referenced BOs
Date: Mon, 2 Dec 2019 12:50:20 +0000	[thread overview]
Message-ID: <7258aca4-115d-d511-4c0a-fb3ba142f382@arm.com> (raw)
Message-ID: <20191202125020.Hkh83VzX_-8zPvsCka2PrPrqKAN1jUCvzQbYFLCJJCs@z> (raw)
In-Reply-To: <20191129135908.2439529-9-boris.brezillon@collabora.com>

On 29/11/2019 1:59 pm, Boris Brezillon wrote:
> Userspace might tag a BO purgeable while it's still referenced by GPU
> jobs. We need to make sure the shrinker does not purge such BOs until
> all jobs referencing it are finished.

Nit: for extra robustness, perhaps it's worth using the refcount_t API 
rather than bare atomic_t?

Robin.

> Fixes: 013b65101315 ("drm/panfrost: Add madvise and shrinker support")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Boris Brezillon <boris.brezillon@collabora.com>
> ---
>   drivers/gpu/drm/panfrost/panfrost_drv.c          | 1 +
>   drivers/gpu/drm/panfrost/panfrost_gem.h          | 6 ++++++
>   drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c | 2 ++
>   drivers/gpu/drm/panfrost/panfrost_job.c          | 7 ++++++-
>   4 files changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/panfrost/panfrost_drv.c b/drivers/gpu/drm/panfrost/panfrost_drv.c
> index b406b5243b40..297c0e7304d2 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_drv.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_drv.c
> @@ -166,6 +166,7 @@ panfrost_lookup_bos(struct drm_device *dev,
>   			break;
>   		}
>   
> +		atomic_inc(&bo->gpu_usecount);
>   		job->mappings[i] = mapping;
>   	}
>   
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem.h b/drivers/gpu/drm/panfrost/panfrost_gem.h
> index ca1bc9019600..b3517ff9630c 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem.h
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem.h
> @@ -30,6 +30,12 @@ struct panfrost_gem_object {
>   		struct mutex lock;
>   	} mappings;
>   
> +	/*
> +	 * Count the number of jobs referencing this BO so we don't let the
> +	 * shrinker reclaim this object prematurely.
> +	 */
> +	atomic_t gpu_usecount;
> +
>   	bool noexec		:1;
>   	bool is_heap		:1;
>   };
> diff --git a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> index b36df326c860..288e46c40673 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_gem_shrinker.c
> @@ -41,6 +41,8 @@ static bool panfrost_gem_purge(struct drm_gem_object *obj)
>   	struct drm_gem_shmem_object *shmem = to_drm_gem_shmem_obj(obj);
>   	struct panfrost_gem_object *bo = to_panfrost_bo(obj);
>   
> +	if (atomic_read(&bo->gpu_usecount))
> +		return false;
>   
>   	if (!mutex_trylock(&shmem->pages_lock))
>   		return false;
> diff --git a/drivers/gpu/drm/panfrost/panfrost_job.c b/drivers/gpu/drm/panfrost/panfrost_job.c
> index c85d45be3b5e..2b12aa87ff32 100644
> --- a/drivers/gpu/drm/panfrost/panfrost_job.c
> +++ b/drivers/gpu/drm/panfrost/panfrost_job.c
> @@ -270,8 +270,13 @@ static void panfrost_job_cleanup(struct kref *ref)
>   	dma_fence_put(job->render_done_fence);
>   
>   	if (job->mappings) {
> -		for (i = 0; i < job->bo_count; i++)
> +		for (i = 0; i < job->bo_count; i++) {
> +			if (!job->mappings[i])
> +				break;
> +
> +			atomic_dec(&job->mappings[i]->obj->gpu_usecount);
>   			panfrost_gem_mapping_put(job->mappings[i]);
> +		}
>   		kvfree(job->mappings);
>   	}
>   
> 
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  parent reply	other threads:[~2019-12-02 12:50 UTC|newest]

Thread overview: 87+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-29 13:59 [PATCH 0/8] panfrost: Fixes for 5.4 Boris Brezillon
2019-11-29 13:59 ` [PATCH 1/8] drm/panfrost: Make panfrost_job_run() return an ERR_PTR() instead of NULL Boris Brezillon
2019-11-29 13:59   ` Boris Brezillon
2019-11-29 14:19   ` Steven Price
2019-11-29 14:19     ` Steven Price
2019-11-29 14:31     ` Boris Brezillon
2019-11-29 14:31       ` Boris Brezillon
2019-11-29 14:38       ` Steven Price
2019-11-29 14:38         ` Steven Price
2019-11-29 19:32         ` Boris Brezillon
2019-11-29 19:32           ` Boris Brezillon
2019-11-29 13:59 ` [PATCH 2/8] drm/panfrost: Fix a race in panfrost_ioctl_madvise() Boris Brezillon
2019-11-29 13:59   ` Boris Brezillon
2019-11-29 14:24   ` Steven Price
2019-11-29 14:24     ` Steven Price
2019-11-29 14:33     ` Boris Brezillon
2019-11-29 14:33       ` Boris Brezillon
2019-11-29 14:40       ` Steven Price
2019-11-29 14:40         ` Steven Price
2019-11-29 20:07         ` Daniel Vetter
2019-11-29 20:07           ` Daniel Vetter
2019-11-29 21:45           ` Boris Brezillon
2019-11-29 21:45             ` Boris Brezillon
2019-12-05 23:08       ` Rob Herring
2019-12-05 23:08         ` Rob Herring
2019-12-06  7:53         ` Boris Brezillon
2019-12-06  7:53           ` Boris Brezillon
2019-12-06  8:08           ` Boris Brezillon
2019-12-06  8:08             ` Boris Brezillon
2019-11-29 13:59 ` [PATCH 3/8] drm/panfrost: Fix a BO leak in panfrost_ioctl_mmap_bo() Boris Brezillon
2019-11-29 13:59   ` Boris Brezillon
2019-11-29 14:26   ` Steven Price
2019-11-29 14:26     ` Steven Price
2019-11-29 13:59 ` [PATCH 4/8] drm/panfrost: Fix a race in panfrost_gem_free_object() Boris Brezillon
2019-11-29 13:59   ` Boris Brezillon
2019-11-29 14:28   ` Steven Price
2019-11-29 14:28     ` Steven Price
2019-11-29 13:59 ` [PATCH 5/8] drm/panfrost: Open/close the perfcnt BO Boris Brezillon
2019-11-29 13:59   ` Boris Brezillon
2019-11-29 14:34   ` Steven Price
2019-11-29 14:34     ` Steven Price
2019-11-29 13:59 ` [PATCH 6/8] drm/panfrost: Make sure imported/exported BOs are never purged Boris Brezillon
2019-11-29 13:59   ` Boris Brezillon
2019-11-29 14:14   ` Boris Brezillon
2019-11-29 14:14     ` Boris Brezillon
2019-11-29 14:45   ` Steven Price
2019-11-29 14:45     ` Steven Price
2019-11-29 14:52     ` Boris Brezillon
2019-11-29 14:52       ` Boris Brezillon
2019-11-29 20:12   ` Daniel Vetter
2019-11-29 20:12     ` Daniel Vetter
2019-11-29 21:09     ` Boris Brezillon
2019-11-29 21:09       ` Boris Brezillon
2019-12-02  8:52       ` Daniel Vetter
2019-12-02  8:52         ` Daniel Vetter
2019-12-02  9:50         ` Boris Brezillon
2019-12-02  9:50           ` Boris Brezillon
2019-11-29 13:59 ` [PATCH 7/8] drm/panfrost: Add the panfrost_gem_mapping concept Boris Brezillon
2019-11-29 13:59   ` Boris Brezillon
2019-11-29 15:37   ` Steven Price
2019-11-29 15:37     ` Steven Price
2019-11-29 20:14   ` Daniel Vetter
2019-11-29 20:14     ` Daniel Vetter
2019-11-29 21:36     ` Boris Brezillon
2019-11-29 21:36       ` Boris Brezillon
2019-12-02  8:55       ` Daniel Vetter
2019-12-02  8:55         ` Daniel Vetter
2019-12-02  9:13         ` Boris Brezillon
2019-12-02  9:13           ` Boris Brezillon
2019-12-02  9:44           ` Daniel Vetter
2019-12-02  9:44             ` Daniel Vetter
2019-12-04 11:41             ` Steven Price
2019-12-04 11:41               ` Steven Price
2019-11-29 13:59 ` [PATCH 8/8] drm/panfrost: Make sure the shrinker does not reclaim referenced BOs Boris Brezillon
2019-11-29 13:59   ` Boris Brezillon
2019-11-29 15:48   ` Steven Price
2019-11-29 15:48     ` Steven Price
2019-11-29 16:07     ` Boris Brezillon
2019-11-29 16:07       ` Boris Brezillon
2019-11-29 16:12       ` Steven Price
2019-11-29 16:12         ` Steven Price
2019-12-02 12:50   ` Robin Murphy [this message]
2019-12-02 12:50     ` Robin Murphy
2019-12-02 13:32     ` Boris Brezillon
2019-12-02 13:32       ` Boris Brezillon
2019-11-29 14:23 ` [PATCH 0/8] panfrost: Fixes for 5.4 Alyssa Rosenzweig
2019-12-06 17:16 ` Rob Herring

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