[PATCH] drm/virtio: delay pinning the pages till first use

[Chia-I Wu]

On Tue, Nov 2, 2021 at 6:07 AM Gerd Hoffmann <kraxel at redhat.com> wrote:
>
> On Tue, Nov 02, 2021 at 12:31:39PM +0100, Maksym Wezdecki wrote:
> > From: mwezdeck <maksym.wezdecki at collabora.co.uk>
> >
> > The idea behind the commit:
> >   1. not pin the pages during resource_create ioctl
> >   2. pin the pages on the first use during:
> >       - transfer_*_host ioctl
> >         - map ioctl
>
> i.e. basically lazy pinning.  Approach looks sane to me.
>
> >   3. introduce new ioctl for pinning pages on demand
>
> What is the use case for this ioctl?
> In any case this should be a separate patch.

Lazy pinning can be a nice optimization that userspace does not
necessarily need to know about.  This patch however skips pinning for
execbuffer ioctl and introduces a new pin ioctl instead.  That is a
red flag.