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Date:   Wed, 18 Nov 2020 14:27:25 -0800
From:   Andrew Morton <akpm@linux-foundation.org>
To:     christian.koenig@amd.com
Cc:     Christian =?ISO-8859-1?Q?K=F6nig?= 
        <ckoenig.leichtzumerken@gmail.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, linaro-mm-sig@lists.linaro.org,
        dri-devel@lists.freedesktop.org, linux-media@vger.kernel.org
Subject: Re: [PATCH 1/2] mm: mmap: fix fput in error path v2
Message-Id: <20201118142725.aa4678810546c70520dd5d74@linux-foundation.org>
In-Reply-To: <e5a25173-ebea-d856-ed25-45437769f17f@gmail.com>
References: <20201106114806.46015-1-christian.koenig@amd.com>
        <20201106114806.46015-2-christian.koenig@amd.com>
        <20201106144811.cf228ca9278ec78887d42960@linux-foundation.org>
        <e5a25173-ebea-d856-ed25-45437769f17f@gmail.com>
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On Wed, 18 Nov 2020 11:57:44 +0100 Christian K=F6nig <ckoenig.leichtzumerke=
n@gmail.com> wrote:

> Am 06.11.20 um 23:48 schrieb Andrew Morton:
> > On Fri,  6 Nov 2020 12:48:05 +0100 "Christian K=F6nig" <ckoenig.leichtz=
umerken@gmail.com> wrote:
> >
> >> Patch "495c10cc1c0c CHROMIUM: dma-buf: restore args..."
> >> adds a workaround for a bug in mmap_region.
> >>
> >> As the comment states ->mmap() callback can change
> >> vma->vm_file and so we might call fput() on the wrong file.
> >>
> >> Revert the workaround and proper fix this in mmap_region.
> >>
> > Seems correct, best I can tell.  Presumably all ->mmap() instances will
> > correctly fput() to original file* if they're rewriting vma->vm_file.
>=20
> Yes, exactly.
>=20
> Patch #2 provides a helper to make sure that everybody gets the=20
> get_file()/fput() correctly while updating vma->vm_file.
>=20
> Can I add your acked-by to the patches and push them upstream through=20
> drm-misc-next?

Please go ahead.

Acked-by: Andrew Morton <akpm@linux-foundation.org>