Re: [PATCH] drm/exynos: Fix memory leak and release IOMMU mapping structures

[Lukasz Luba <lukasz.luba@arm.com>]

Hi Marek,

On 3/5/20 7:07 AM, Marek Szyprowski wrote:
> Hi Lukasz,
> 
> On 04.03.2020 23:00, Lukasz Luba wrote:
>> There is a memory leak which left some objects not freed. The reference
>> counter of mapping: 'mapping->kref' was 2 when calling
>> arm_iommu_detach_device(), so the release_iommu_mapping() won't be called.
>> Since the old mapping structure is not going to be used any more (because
>> it is detached and new one attached), call arm_iommu_release_mapping()
>> to trigger cleanup.
> 
> This will break IOMMU support in Exynos DRM if deferred probe happens.
> Here is a proper fix:

I forgot about the deferred probe.

> 
> https://patchwork.kernel.org/patch/11415715/
> 
> The mapping initially created by DMA-mapping framework should be
> attached back when Exynos DRM releases the subdev device.
> 

Indeed, as you responded in that thread with the example, there is
more dependencies and attaching back the old mapping will work.

I am going add my reviewed-by to your patch.

Regards,
Lukasz