Received-SPF: pass (google.com: best guess record for domain of linux-crypto-owner@vger.kernel.org designates 209.132.180.67 as permitted sender) client-ip=209.132.180.67;
Date:   Wed, 23 Oct 2019 13:03:06 -0400
From:   Jerome Glisse <jglisse@redhat.com>
To:     Jean-Philippe Brucker <jean-philippe@linaro.org>
Cc:     "zhangfei.gao@foxmail.com" <zhangfei.gao@foxmail.com>,
        francois.ozog@linaro.org, Herbert Xu <herbert@gondor.apana.org.au>,
        Arnd Bergmann <arnd@arndb.de>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Zaibo Xu <xuzaibo@huawei.com>, ilias.apalodimas@linaro.org,
        linux-kernel@vger.kernel.org, linux-crypto@vger.kernel.org,
        Wangzhou <wangzhou1@hisilicon.com>, grant.likely@arm.com,
        "haojian . zhuang" <haojian.zhuang@linaro.org>,
        Zhangfei Gao <zhangfei.gao@linaro.org>,
        Kenneth Lee <liguozhu@hisilicon.com>,
        linux-accelerators@lists.ozlabs.org, kenneth-lee-2012@foxmail.com
Subject: Re: [PATCH v6 2/3] uacce: add uacce driver
Message-ID: <20191023170306.GC4163@redhat.com>
References: <1571214873-27359-1-git-send-email-zhangfei.gao@linaro.org>
 <1571214873-27359-3-git-send-email-zhangfei.gao@linaro.org>
 <20191016172802.GA1533448@lophozonia>
 <5da9a9cd.1c69fb81.9f8e8.60faSMTPIN_ADDED_BROKEN@mx.google.com>
 <20191023074227.GA264888@lophozonia>
MIME-Version: 1.0
In-Reply-To: <20191023074227.GA264888@lophozonia>
User-Agent: Mutt/1.12.1 (2019-06-15)
Content-Type: text/plain; charset=WINDOWS-1252
Content-Transfer-Encoding: quoted-printable
Content-Disposition: inline
Sender: linux-crypto-owner@vger.kernel.org
Precedence: bulk

On Wed, Oct 23, 2019 at 09:42:27AM +0200, Jean-Philippe Brucker wrote:
> On Fri, Oct 18, 2019 at 08:01:44PM +0800, zhangfei.gao@foxmail.com wrote:

[...]

> > > > +static int uacce_fops_mmap(struct file *filep, struct vm_area_stru=
ct *vma)
> > > > +{
> > > > +=09struct uacce_queue *q =3D filep->private_data;
> > > > +=09struct uacce_device *uacce =3D q->uacce;
> > > > +=09struct uacce_qfile_region *qfr;
> > > > +=09enum uacce_qfrt type =3D 0;
> > > > +=09unsigned int flags =3D 0;
> > > > +=09int ret;
> > > > +
> > > > +=09if (vma->vm_pgoff < UACCE_QFRT_MAX)
> > > > +=09=09type =3D vma->vm_pgoff;
> > > > +
> > > > +=09vma->vm_flags |=3D VM_DONTCOPY | VM_DONTEXPAND;
> > > > +
> > > > +=09mutex_lock(&uacce_mutex);
>=20
> By the way, lockdep detects a possible unsafe locking scenario here,
> because we're taking the uacce_mutex even though mmap called us with the
> mmap_sem held for writing. Conversely uacce_fops_release() takes the
> mmap_sem for writing while holding the uacce_mutex. I think it can be
> fixed easily, if we simply remove the use of mmap_sem in
> uacce_fops_release(), since it's only taken to do some accounting which
> doesn't look right.

I think you need to remove the RLIMIT_DATA accounting altogether. Assume
it is not an issue for now and revisit latter when it becomes one as i
am not sure we want to add this queue memory accounting to RLIMIT_DATA
in the first place. Maybe a memory cgroup. In anycases it is safer to
delay this discussion to latter.

Cheers,
J=E9r=F4me