linux-kernel - Re: [PATCH] drm/ttm: don't set page->mapping

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Message-ID: <20201125180606.GQ5487@ziepe.ca>
Date:   Wed, 25 Nov 2020 14:06:06 -0400
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Daniel Vetter <daniel.vetter@...ll.ch>
Cc:     DRI Development <dri-devel@...ts.freedesktop.org>,
        Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
        Linux MM <linux-mm@...ck.org>, linux-xfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, LKML <linux-kernel@...r.kernel.org>,
        Thomas Hellstrom <thellstrom@...are.com>,
        Brian Paul <brianp@...are.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Christian Koenig <christian.koenig@....com>,
        Huang Rui <ray.huang@....com>
Subject: Re: [PATCH] drm/ttm: don't set page->mapping

On Wed, Nov 25, 2020 at 05:28:32PM +0100, Daniel Vetter wrote:
> On Wed, Nov 25, 2020 at 5:25 PM Daniel Vetter <daniel.vetter@...ll.ch> wrote:
> >
> > Random observation while trying to review Christian's patch series to
> > stop looking at struct page for dma-buf imports.
> >
> > This was originally added in
> >
> > commit 58aa6622d32af7d2c08d45085f44c54554a16ed7
> > Author: Thomas Hellstrom <thellstrom@...are.com>
> > Date:   Fri Jan 3 11:47:23 2014 +0100
> >
> >     drm/ttm: Correctly set page mapping and -index members
> >
> >     Needed for some vm operations; most notably unmap_mapping_range() with
> >     even_cows = 0.
> >
> >     Signed-off-by: Thomas Hellstrom <thellstrom@...are.com>
> >     Reviewed-by: Brian Paul <brianp@...are.com>
> >
> > but we do not have a single caller of unmap_mapping_range with
> > even_cows == 0. And all the gem drivers don't do this, so another
> > small thing we could standardize between drm and ttm drivers.
> >
> > Plus I don't really see a need for unamp_mapping_range where we don't
> > want to indiscriminately shoot down all ptes.
> >
> > Cc: Thomas Hellstrom <thellstrom@...are.com>
> > Cc: Brian Paul <brianp@...are.com>
> > Signed-off-by: Daniel Vetter <daniel.vetter@...el.com>
> > Cc: Christian Koenig <christian.koenig@....com>
> > Cc: Huang Rui <ray.huang@....com>
> 
> Apologies again, this shouldn't have been included. But at least I
> have an idea now why this patch somehow was included in the git
> send-email. Lovely interface :-/

I wrote a bit of a script around this because git send-email just too
hard to use

The key workflow change I made was to have it prepare all the emails
to send and open them in an editor for review - exactly as they would
be sent to the lists.

It uses a empty 'cover-letter' commit and automatically transforms it
into exactly the right stuff. Keeps track of everything you send in
git, and there is a little tool to auto-run git range-diff to help
build change logs..

https://github.com/jgunthorpe/Kernel-Maintainer-Tools/blob/master/gj_tools/cmd_send_patches.py

I've been occasionaly wondering if I should suggest Konstantin add a
sending side to b4, maybe using some of those ideas..

(careful if you run it, it does autosend without prompting)

Jason