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Mon, 22 Jun 2020 19:27:42 +0000 Received: from pps.filterd (userp3020.oracle.com [127.0.0.1]) by userp3020.oracle.com (8.16.0.42/8.16.0.42) with SMTP id 05MJO6wN008547; Mon, 22 Jun 2020 19:25:42 GMT Received: from userv0122.oracle.com (userv0122.oracle.com [156.151.31.75]) by userp3020.oracle.com with ESMTP id 31sv7qm43j-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Mon, 22 Jun 2020 19:25:42 +0000 Received: from abhmp0012.oracle.com (abhmp0012.oracle.com [141.146.116.18]) by userv0122.oracle.com (8.14.4/8.14.4) with ESMTP id 05MJPe8P017178; Mon, 22 Jun 2020 19:25:41 GMT Received: from [10.39.220.59] (/10.39.220.59) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Mon, 22 Jun 2020 19:25:40 +0000 Subject: Re: [RFC PATCH] xen/privcmd: Convert get_user_pages*() to pin_user_pages*() To: Souptick Joarder Cc: John Hubbard , Juergen Gross , sstabellini@kernel.org, xen-devel@lists.xenproject.org, linux-kernel@vger.kernel.org, paul@xen.org References: <1592363698-4266-1-git-send-email-jrdr.linux@gmail.com> <5a5133e6-b84d-a2cc-fcb4-db85c4e65d62@oracle.com> From: Boris Ostrovsky Autocrypt: addr=boris.ostrovsky@oracle.com; 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Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.8.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 7bit Content-Language: en-US X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9660 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 suspectscore=0 mlxlogscore=999 mlxscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006220127 X-Proofpoint-Virus-Version: vendor=nai engine=6000 definitions=9660 signatures=668680 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 adultscore=0 lowpriorityscore=0 mlxlogscore=999 cotscore=-2147483648 mlxscore=0 phishscore=0 priorityscore=1501 malwarescore=0 bulkscore=0 suspectscore=0 clxscore=1015 impostorscore=0 spamscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2004280000 definitions=main-2006220127 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 6/22/20 3:28 PM, Souptick Joarder wrote: > On Tue, Jun 23, 2020 at 12:40 AM Boris Ostrovsky > wrote: >> On 6/22/20 2:52 PM, Souptick Joarder wrote: >>> I read the code again. I think, this check is needed to handle a scenario when >>> lock_pages() return -ENOSPC. Better to keep this check. Let me post v2 of this >>> RFC for a clear view. >> >> Actually, error handling seems to be somewhat broken here. If >> lock_pages() returns number of pinned pages then that's what we end up >> returning from privcmd_ioctl_dm_op(), all the way to user ioctl(). Which >> I don't think is right, we should return proper (negative) error. >> > What -ERRNO is more appropriate here ? -ENOSPC ? You can simply pass along error code that get_user_pages_fast() returned. -boris