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

[Lukasz Luba]

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