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Date:   Tue, 18 May 2021 08:04:42 +1000
From:   Stephen Rothwell <sfr@rothwell.id.au>
To:     Daniel Vetter <daniel.vetter@ffwll.ch>
Cc:     Christoph Hellwig <hch@infradead.org>,
        Stephen Rothwell <sfr@canb.auug.org.au>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Tomasz Figa <tfiga@chromium.org>,
        Marek Szyprowski <m.szyprowski@samsung.com>,
        Mauro Carvalho Chehab <mchehab@kernel.org>,
        DRI Development <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Linux-MM <linux-mm@kvack.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        Linux Media Mailing List <linux-media@vger.kernel.org>,
        linux-samsung-soc <linux-samsung-soc@vger.kernel.org>
Subject: Re: [PULL] topic/iomem-mmap-vs-gup
Message-ID: <20210518080442.28080686@elm.ozlabs.ibm.com>
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Hi Daniel,

On Mon, 17 May 2021 17:29:35 +0200 Daniel Vetter <daniel.vetter@ffwll.ch> w=
rote:
>
> On Mon, May 10, 2021 at 9:30 AM Christoph Hellwig <hch@infradead.org> wro=
te:
> >
> > On Mon, May 10, 2021 at 09:16:58AM +0200, Daniel Vetter wrote: =20
> > > > End result: not pulling it, unless somebody can explain to me in sm=
all
> > > > words why I'm wrong and have the mental capacity of a damaged roden=
t. =20
> > >
> > > No rodents I think, just more backstory of how this all fits. tldr;
> > > pin_user_pages is the only safe use of this vb2 userptr thing. =20
> >
> > Yes, which is why I advocate for just ripping the follow_pfn path
> > out entirely.  It could have been used for crazy ad dangerous peer to
> > peer transfers outside of any infrastructure making it safe, or for
> > pre-CMA kernel memory carveouts for lage contiguous memory allocations
> > (which are pretty broken by design as well).  So IMHO the only sensible
> > thing is to remove this cruft entirely, and if it breaks a currently
> > working setup (which I think is unlikely) we'll have to make sure it
> > can work the proper way. =20
>=20
> Since I'm not getting any cozy consenus vibes here on any option I
> think I'll just drop this.
>=20
> Stephen, can you pls drop
>=20
> git://anongit.freedesktop.org/drm/drm topic/iomem-mmap-vs-gup
>=20
> from linux-next? It's not going anywhere. I'll also go ahead and
> delete the branch, to make sure you catch this update :-)

I have dropped this now.  Thanks for letting me know.

--=20
Cheers,
Stephen Rothwell

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