From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753071AbcHAXAx (ORCPT ); Mon, 1 Aug 2016 19:00:53 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:63223 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752927AbcHAXAq (ORCPT ); Mon, 1 Aug 2016 19:00:46 -0400 X-IBM-Helo: d24dlp01.br.ibm.com X-IBM-MailFrom: mauricfo@linux.vnet.ibm.com X-IBM-RcptTo: linux-doc@vger.kernel.org;linux-kernel@vger.kernel.org From: Mauricio Faria de Oliveira To: linux-doc@vger.kernel.org, linux-kernel@vger.kernel.org, linux-nvme@lists.infradead.org, corbet@lwn.net, akpm@linux-foundation.org, rmk+kernel@arm.linux.org.uk, keith.busch@intel.com, axboe@fb.com, benh@kernel.crashing.org, mpe@ellerman.id.au Cc: k.kozlowski@samsung.com Subject: [PATCH v4 0/3] dma-mapping, powerpc, nvme: introduce the DMA_ATTR_NO_WARN attribute Date: Mon, 1 Aug 2016 19:59:47 -0300 X-Mailer: git-send-email 1.8.3.1 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16080122-0028-0000-0000-0000012CD5A7 X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16080122-0029-0000-0000-000013DE10ED Message-Id: <1470092390-25451-1-git-send-email-mauricfo@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-08-01_15:,, signatures=0 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 spamscore=0 suspectscore=0 malwarescore=0 phishscore=0 adultscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1604210000 definitions=main-1608010236 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This patchset introduces dma_attr DMA_ATTR_NO_WARN (just like __GFP_NOWARN), which tells the DMA-mapping subsystem to suppress allocation failure reports. On some architectures allocation failures are reported with error messages to the system logs. Although this can help to identify and debug problems, drivers which handle failures (eg, retry later) have no problems with them, and can actually flood the system logs with error messages that aren't any problem at all, depending on the implementation of the retry mechanism. So, this provides a way for drivers to avoid those error messages on calls where allocation failures are not a problem, and shouldn't bother the logs. - Patch 1/3 introduces the dma_attr DMA_ATTR_NO_WARN. - Patch 2/3 implements support for it on powerpc arch (where this problem was observed; it's possible to extend support for more archs) - Patch 3/3 implements it on the nvme driver (which might repeatedly trip on allocation failures due to high load, flooding system logs with error messages at least on powerpc: "iommu_alloc failed") Changelog: v4: - rebase for commit 53a4b60 dma-mapping: use unsigned long for dma_attrs. - reorder patches 2/3 and 3/3. v3: - nvme: use DMA_ATTR_NO_WARN when ret = BLK_MQ_RQ_QUEUE_BUSY (io will be requeued) but not when ret = BLK_MQ_RQ_QUEUE_ERROR (io will be failed). thanks: Masayoshi Mizuma v2: - all: address warnings from checkpatch.pl (line wrapping and typos) Tested on next-20160801. Mauricio Faria de Oliveira (3): dma-mapping: introduce the DMA_ATTR_NO_WARN attribute powerpc: implement the DMA_ATTR_NO_WARN attribute nvme: use the DMA_ATTR_NO_WARN attribute Documentation/DMA-attributes.txt | 17 +++++++++++++++++ arch/powerpc/kernel/iommu.c | 6 ++++-- drivers/nvme/host/pci.c | 3 ++- include/linux/dma-mapping.h | 5 +++++ 4 files changed, 28 insertions(+), 3 deletions(-) -- 1.8.3.1