From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755839AbcGFVEi (ORCPT ); Wed, 6 Jul 2016 17:04:38 -0400 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:43483 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755474AbcGFVEg (ORCPT ); Wed, 6 Jul 2016 17:04:36 -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, linuxppc-dev@lists.ozlabs.org Cc: Jonathan Corbet , Andrew Morton , Russell King , Keith Busch , Jens Axboe , Benjamin Herrenschmidt , Michael Ellerman Subject: [PATCH 0/3] dma, nvme, powerpc: introduce and implement DMA_ATTR_NO_WARN Date: Wed, 6 Jul 2016 18:03:30 -0300 X-Mailer: git-send-email 1.8.3.1 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 16070621-1523-0000-0000-00000202AD3A X-IBM-AV-DETECTION: SAVI=unused REMOTE=unused XFE=unused x-cbparentid: 16070621-1524-0000-0000-0000270265CC Message-Id: <1467839013-22481-1-git-send-email-mauricfo@linux.vnet.ibm.com> X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10432:,, definitions=2016-07-06_09:,, 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-1607060179 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 supress 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 and documents the new dma_attr. - Patch 2/3 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") - Patch 3/3 implements support for it on powerpc arch (where this problem was observed. It's possible to extend support for more archs if the patchset is welcome). Mauricio Faria de Oliveira (3): dma: introduce DMA_ATTR_NO_WARN nvme: implement DMA_ATTR_NO_WARN powerpc: implement DMA_ATTR_NO_WARN Documentation/DMA-attributes.txt | 17 +++++++++++++++++ arch/powerpc/kernel/iommu.c | 4 ++-- drivers/nvme/host/pci.c | 10 ++++++++-- include/linux/dma-attrs.h | 1 + 4 files changed, 28 insertions(+), 4 deletions(-) -- 1.8.3.1