linux-kernel - Re: [RFC PATCH 1/2] mm,drm/ttm: Block fast GUP to TTM huge pages

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Message-ID: <20210325120103.GV2356281@nvidia.com>
Date:   Thu, 25 Mar 2021 09:01:03 -0300
From:   Jason Gunthorpe <jgg@...dia.com>
To:     Thomas Hellström (Intel) 
        <thomas_os@...pmail.org>
Cc:     Christian König <christian.koenig@....com>,
        David Airlie <airlied@...ux.ie>, linux-kernel@...r.kernel.org,
        dri-devel@...ts.freedesktop.org, linux-mm@...ck.org,
        Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [RFC PATCH 1/2] mm,drm/ttm: Block fast GUP to TTM huge pages

On Thu, Mar 25, 2021 at 12:53:15PM +0100, Thomas Hellström (Intel) wrote:

> Nope. The point here was that in this case, to make sure mmap uses the
> correct VA to give us a reasonable chance of alignement, the driver might
> need to be aware of and do trickery with the huge page-table-entry sizes
> anyway, although I think in most cases a standard helper for this can be
> supplied.

Of course the driver needs some way to influence the VA mmap uses,
gernally it should align to the natural page size of the device

Jason