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Subject: Re: [PATCH] uacce: unmap remaining mmapping from user space
To:     Xu Zaibo <xuzaibo@huawei.com>,
        Greg Kroah-Hartman <gregkh@linuxfoundation.org>,
        Arnd Bergmann <arnd@arndb.de>,
        Herbert Xu <herbert@gondor.apana.org.au>,
        jonathan.cameron@huawei.com, dave.jiang@intel.com,
        grant.likely@arm.com, jean-philippe <jean-philippe@linaro.org>,
        Jerome Glisse <jglisse@redhat.com>,
        ilias.apalodimas@linaro.org, francois.ozog@linaro.org,
        kenneth-lee-2012@foxmail.com, Wangzhou <wangzhou1@hisilicon.com>,
        "haojian . zhuang" <haojian.zhuang@linaro.org>,
        guodong.xu@linaro.org
Cc:     iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org,
        linux-accelerators@lists.ozlabs.org, linux-crypto@vger.kernel.org
References: <1582528016-2873-1-git-send-email-zhangfei.gao@linaro.org>
 <a4716453-0607-d613-e632-173d1ebc424e@huawei.com>
From:   zhangfei <zhangfei.gao@linaro.org>
Message-ID: <cf1f7ec2-7181-63fd-598d-b74d5a3efa15@linaro.org>
Date:   Tue, 25 Feb 2020 16:33:37 +0800
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Hi, Zaibo

On 2020/2/24 下午3:17, Xu Zaibo wrote:
>>   @@ -585,6 +595,13 @@ void uacce_remove(struct uacce_device *uacce)
>>           cdev_device_del(uacce->cdev, &uacce->dev);
>>       xa_erase(&uacce_xa, uacce->dev_id);
>>       put_device(&uacce->dev);
>> +
>> +    /*
>> +     * unmap remainning mapping from user space, preventing user still
>> +     * access the mmaped area while parent device is already removed
>> +     */
>> +    if (uacce->inode)
>> +        unmap_mapping_range(uacce->inode->i_mapping, 0, 0, 1);
> Should we unmap them at the first of 'uacce_remove',  and before 
> 'uacce_put_queue'?
>
We can do this,
Though it does not matter, since user space can not interrupt kernel 
function uacce_remove.

Thanks