From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <SRS0=3KsH=DP=kvack.org=owner-linux-mm@kernel.org>
X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on
	aws-us-west-2-korg-lkml-1.web.codeaurora.org
X-Spam-Level: 
X-Spam-Status: No, score=-11.6 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH,
	DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,
	INCLUDES_PATCH,MAILING_LIST_MULTI,NICE_REPLY_A,SIGNED_OFF_BY,SPF_HELO_NONE,
	SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable
	autolearn_force=no version=3.4.0
Received: from mail.kernel.org (mail.kernel.org [198.145.29.99])
	by smtp.lore.kernel.org (Postfix) with ESMTP id 81164C433E7
	for <linux-mm@archiver.kernel.org>; Thu,  8 Oct 2020 21:49:08 +0000 (UTC)
Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17])
	by mail.kernel.org (Postfix) with ESMTP id C9B9D22244
	for <linux-mm@archiver.kernel.org>; Thu,  8 Oct 2020 21:49:07 +0000 (UTC)
Authentication-Results: mail.kernel.org;
	dkim=pass (2048-bit key) header.d=nvidia.com header.i=@nvidia.com header.b="lT3noPjN"
DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org C9B9D22244
Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=nvidia.com
Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org
Received: by kanga.kvack.org (Postfix)
	id E46A96B005C; Thu,  8 Oct 2020 17:49:06 -0400 (EDT)
Received: by kanga.kvack.org (Postfix, from userid 40)
	id DF6836B005D; Thu,  8 Oct 2020 17:49:06 -0400 (EDT)
X-Delivered-To: int-list-linux-mm@kvack.org
Received: by kanga.kvack.org (Postfix, from userid 63042)
	id CBE676B0062; Thu,  8 Oct 2020 17:49:06 -0400 (EDT)
X-Delivered-To: linux-mm@kvack.org
Received: from forelay.hostedemail.com (smtprelay0178.hostedemail.com [216.40.44.178])
	by kanga.kvack.org (Postfix) with ESMTP id 9F0A96B005C
	for <linux-mm@kvack.org>; Thu,  8 Oct 2020 17:49:06 -0400 (EDT)
Received: from smtpin15.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251])
	by forelay01.hostedemail.com (Postfix) with ESMTP id 3ED94180AD806
	for <linux-mm@kvack.org>; Thu,  8 Oct 2020 21:49:06 +0000 (UTC)
X-FDA: 77350099092.15.leg43_3e0bdee271db
Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251])
	by smtpin15.hostedemail.com (Postfix) with ESMTP id 16A3A1814B0C7
	for <linux-mm@kvack.org>; Thu,  8 Oct 2020 21:49:06 +0000 (UTC)
X-HE-Tag: leg43_3e0bdee271db
X-Filterd-Recvd-Size: 4587
Received: from hqnvemgate26.nvidia.com (hqnvemgate26.nvidia.com [216.228.121.65])
	by imf17.hostedemail.com (Postfix) with ESMTP
	for <linux-mm@kvack.org>; Thu,  8 Oct 2020 21:49:05 +0000 (UTC)
Received: from hqmail.nvidia.com (Not Verified[216.228.121.13]) by hqnvemgate26.nvidia.com (using TLS: TLSv1.2, AES256-SHA)
	id <B5f7f89430001>; Thu, 08 Oct 2020 14:48:51 -0700
Received: from [10.2.48.215] (10.124.1.5) by HQMAIL107.nvidia.com
 (172.20.187.13) with Microsoft SMTP Server (TLS) id 15.0.1473.3; Thu, 8 Oct
 2020 21:49:03 +0000
Subject: Re: [PATCH 1/4] mm: introduce vma_set_file function v2
To: =?UTF-8?Q?Christian_K=c3=b6nig?= <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>, <chris@chris-wilson.co.uk>,
	<airlied@redhat.com>, <akpm@linux-foundation.org>, <daniel@ffwll.ch>,
	<sumit.semwal@linaro.org>
References: <20201008112342.9394-1-christian.koenig@amd.com>
From: John Hubbard <jhubbard@nvidia.com>
Message-ID: <b6b77e60-f93d-efe4-e267-983a2bdbbe71@nvidia.com>
Date: Thu, 8 Oct 2020 14:49:03 -0700
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101
 Thunderbird/68.12.0
MIME-Version: 1.0
In-Reply-To: <20201008112342.9394-1-christian.koenig@amd.com>
Content-Type: text/plain; charset="utf-8"; format=flowed
Content-Language: en-US
Content-Transfer-Encoding: quoted-printable
X-Originating-IP: [10.124.1.5]
X-ClientProxiedBy: HQMAIL101.nvidia.com (172.20.187.10) To
 HQMAIL107.nvidia.com (172.20.187.13)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=nvidia.com; s=n1;
	t=1602193731; bh=7i3jZC1P+1sGlWP35B+/rJtJPgw2xaej/RUlAUDj20A=;
	h=Subject:To:References:From:Message-ID:Date:User-Agent:
	 MIME-Version:In-Reply-To:Content-Type:Content-Language:
	 Content-Transfer-Encoding:X-Originating-IP:X-ClientProxiedBy;
	b=lT3noPjN6nsazaxazrkTAZJXXDq9MU9e9CfYXSbXg8tSCVoorFGM7M/YNUCd42FT1
	 dKH9AByZMwx2YXJQZ83lwCkaqFQWC0YvYb72NUHoCzveaWNranS7KsOFaeMzZWy/6E
	 5FA2ekF8rcO0uhRvVWrbzMmRyHVliNxHzH1Fb166Kd05XkEfBR7t0cddAjnymHDbXa
	 as1wSoVJUoD2zt85swdV8Nl4uYzpW/NZFRmJUKfoaSVqZndhrNIn8JS0NbNJMifnxt
	 X8UwMogZrGtl7zMXYwFpjv6td0b4hP7ukBua0ValYvHsujD4xfCzvmvEgmO/MImwBb
	 8l3Yz+o5Z5zjg==
X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4
Sender: owner-linux-mm@kvack.org
Precedence: bulk
X-Loop: owner-majordomo@kvack.org
List-ID: <linux-mm.kvack.org>

On 10/8/20 4:23 AM, Christian K=C3=B6nig wrote:
> Add the new vma_set_file() function to allow changing
> vma->vm_file with the necessary refcount dance.
>=20
> v2: add more users of this.
>=20
> Signed-off-by: Christian K=C3=B6nig <christian.koenig@amd.com>
> ---
>   drivers/dma-buf/dma-buf.c                  | 16 +++++-----------
>   drivers/gpu/drm/etnaviv/etnaviv_gem.c      |  4 +---
>   drivers/gpu/drm/i915/gem/i915_gem_dmabuf.c |  3 +--
>   drivers/gpu/drm/i915/gem/i915_gem_mman.c   |  4 ++--
>   drivers/gpu/drm/msm/msm_gem.c              |  4 +---
>   drivers/gpu/drm/omapdrm/omap_gem.c         |  3 +--
>   drivers/gpu/drm/vgem/vgem_drv.c            |  3 +--
>   drivers/staging/android/ashmem.c           |  5 ++---
>   include/linux/mm.h                         |  2 ++
>   mm/mmap.c                                  | 16 ++++++++++++++++
>   10 files changed, 32 insertions(+), 28 deletions(-)

Looks like a nice cleanup. Two comments below.

...

> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_mman.c b/drivers/gpu/drm/i=
915/gem/i915_gem_mman.c
> index 3d69e51f3e4d..c9d5f1a38af3 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_mman.c
> @@ -893,8 +893,8 @@ int i915_gem_mmap(struct file *filp, struct vm_area_s=
truct *vma)
>   	 * requires avoiding extraneous references to their filp, hence why
>   	 * we prefer to use an anonymous file for their mmaps.
>   	 */
> -	fput(vma->vm_file);
> -	vma->vm_file =3D anon;
> +	vma_set_file(vma, anon);
> +	fput(anon);

That's one fput() too many, isn't it?

...

> diff --git a/drivers/staging/android/ashmem.c b/drivers/staging/android/a=
shmem.c
> index 10b4be1f3e78..a51dc089896e 100644
> --- a/drivers/staging/android/ashmem.c
> +++ b/drivers/staging/android/ashmem.c
> @@ -450,9 +450,8 @@ static int ashmem_mmap(struct file *file, struct vm_a=
rea_struct *vma)
>   		vma_set_anonymous(vma);
>   	}
>  =20
> -	if (vma->vm_file)
> -		fput(vma->vm_file);
> -	vma->vm_file =3D asma->file;
> +	vma_set_file(vma, asma->file);
> +	fput(asma->file);

Same here: that fput() seems wrong, as it was already done within vma_set_f=
ile().


thanks,
--=20
John Hubbard
NVIDIA