Re: [PATCH RFC 2/4] drm/i915: IOMMU based SVM implementation v13

Chris Wilson
2016-08-15T12:24:23Z

On Mon, Aug 15, 2016 at 01:13:25PM +0100, David Woodhouse wrote:
> On Mon, 2016-08-15 at 13:05 +0100, Chris Wilson wrote:
> > On Mon, Aug 15, 2016 at 02:48:05PM +0300, Mika Kuoppala wrote:
> > >
> > > + struct task_struct *task;
> >
> > We don't need the task, we need the mm.
> >
> > Holding the task is not sufficient.
>
> From the pure DMA point of view, you don't need the MM at all. I handle
> all that from the IOMMU side so it's none of your business, darling.

But you don't keep the mm alive for the duration of device activity,
right? And you don't wait for the device to finish before releasing the
mmu? (iiuc intel-svm.c)
-Chris

--
Chris Wilson, Intel Open Source Technology Centre