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Violators will be prosecuted; Tue, 27 Mar 2018 16:24:12 +0100 Received: from d06av21.portsmouth.uk.ibm.com (d06av21.portsmouth.uk.ibm.com [9.149.105.232]) by b06cxnps3075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id w2RFOBGs11862368; Tue, 27 Mar 2018 15:24:12 GMT Received: from d06av21.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id AA9075205A; Tue, 27 Mar 2018 15:15:28 +0100 (BST) Received: from icon-9-167-242-162.megacenter.de.ibm.com (unknown [9.167.242.162]) by d06av21.portsmouth.uk.ibm.com (Postfix) with ESMTPS id 36B7F52043; Tue, 27 Mar 2018 15:15:28 +0100 (BST) Date: Tue, 27 Mar 2018 17:24:10 +0200 (CEST) From: Sebastian Ott X-X-Sender: sebott@schleppi To: Christoph Hellwig cc: Jesper Nilsson , Geert Uytterhoeven , linux-kernel@vger.kernel.org Subject: Re: dma_zalloc_coherent broken with 57bf5a8963f80fb3828c46c3e3a5b2dd790e09a7 In-Reply-To: <20180327143341.GA4968@lst.de> References: <20180327143341.GA4968@lst.de> User-Agent: Alpine 2.21 (LFD 202 2017-01-01) Organization: =?ISO-8859-15?Q?=22IBM_Deutschland_Research_&_Development_GmbH?= =?ISO-8859-15?Q?_=2F_Vorsitzende_des_Aufsichtsrats=3A_Martina?= =?ISO-8859-15?Q?_Koederitz_Gesch=E4ftsf=FChrung=3A_Dirk_Wittkopp?= =?ISO-8859-15?Q?_Sitz_der_Gesellschaft=3A_B=F6blingen_=2F_Reg?= =?ISO-8859-15?Q?istergericht=3A_Amtsgericht_Stuttgart=2C_HRB_2432?= =?ISO-8859-15?Q?94=22?= MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII X-TM-AS-GCONF: 00 x-cbid: 18032715-0020-0000-0000-0000040A62C6 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 18032715-0021-0000-0000-0000429E664D Message-Id: X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2018-03-27_06:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 priorityscore=1501 malwarescore=0 suspectscore=3 phishscore=0 bulkscore=0 spamscore=0 clxscore=1015 lowpriorityscore=0 impostorscore=0 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1709140000 definitions=main-1803270154 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 27 Mar 2018, Christoph Hellwig wrote: > On Tue, Mar 27, 2018 at 10:12:54AM +0200, Sebastian Ott wrote: > > Hi, > > > > commit 57bf5a8963f80fb3828c46c3e3a5b2dd790e09a7 broke usage of dma > > allocations specifying __GFP_ZERO by silently removing that flag. > > > > Why should "the memory returned [] always be zeroed."? > > Because that is what the current implementations do - we always zero > the memory returned from dma_map_ops.alloc(). What do you mean by current implementations? Arch specific code? At least on s390 we don't do that. dma-mapping.h doesn't do it either. Sebastian