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From:   Daniel Vetter <daniel.vetter@ffwll.ch>
Date:   Wed, 17 Mar 2021 09:04:50 +0100
Message-ID: <CAKMK7uGe4-7EzgYo-rLyhxp5Dft-6V_a610TmL0hRucYTpdmRQ@mail.gmail.com>
Subject: Re: [PATCH 2/3] media/videobuf1|2: Mark follow_pfn usage as unsafe
To:     Christoph Hellwig <hch@infradead.org>
Cc:     DRI Development <dri-devel@lists.freedesktop.org>,
        LKML <linux-kernel@vger.kernel.org>,
        KVM list <kvm@vger.kernel.org>, Linux MM <linux-mm@kvack.org>,
        Linux ARM <linux-arm-kernel@lists.infradead.org>,
        linux-samsung-soc <linux-samsung-soc@vger.kernel.org>,
        "open list:DMA BUFFER SHARING FRAMEWORK" 
        <linux-media@vger.kernel.org>, Tomasz Figa <tfiga@chromium.org>,
        Hans Verkuil <hverkuil-cisco@xs4all.nl>,
        Daniel Vetter <daniel.vetter@intel.com>,
        Jason Gunthorpe <jgg@ziepe.ca>,
        Kees Cook <keescook@chromium.org>,
        Dan Williams <dan.j.williams@intel.com>,
        Andrew Morton <akpm@linux-foundation.org>,
        John Hubbard <jhubbard@nvidia.com>,
        "J??r??me Glisse" <jglisse@redhat.com>, Jan Kara <jack@suse.cz>,
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        Marek Szyprowski <m.szyprowski@samsung.com>,
        Kyungmin Park <kyungmin.park@samsung.com>,
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        Daniel Jordan <daniel.m.jordan@oracle.com>,
        Michel Lespinasse <walken@google.com>
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On Wed, Mar 17, 2021 at 8:22 AM Christoph Hellwig <hch@infradead.org> wrote:
> On Tue, Mar 16, 2021 at 04:52:44PM +0100, Daniel Vetter wrote:
> > My understanding is mostly, but with some objections. And I kinda
> > don't want to let this die in a bikeshed and then not getting rid of
> > follow_pfn as a result. There's enough people who acked this, and the
> > full removal got some nack from Mauro iirc.
>
> Hmm, ok I must have missed that.  I defintively prefer your series over
> doing nothing, but killing the dead horse ASAP would be even better.

I have a bunch of slow-burner things I need to fix in this area of
driver mmaps vs get_user_/follow_ conflicts anyway, I'll add a note to
put the horse out of it's misery in due time. We have a few problems
still where things might get pinned or used where it really shouldn't
be.

Can I count that as an ack on the series? You've touched this quite a
bit recently.

Thanks, Daniel
-- 
Daniel Vetter
Software Engineer, Intel Corporation
http://blog.ffwll.ch