From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,UNPARSEABLE_RELAY,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A339FECDE43 for ; Fri, 19 Oct 2018 00:17:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 535C62145D for ; Fri, 19 Oct 2018 00:17:39 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=oracle.com header.i=@oracle.com header.b="eerNa3xl" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 535C62145D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=oracle.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726816AbeJSIVI (ORCPT ); Fri, 19 Oct 2018 04:21:08 -0400 Received: from aserp2120.oracle.com ([141.146.126.78]:58656 "EHLO aserp2120.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725945AbeJSIVI (ORCPT ); Fri, 19 Oct 2018 04:21:08 -0400 Received: from pps.filterd (aserp2120.oracle.com [127.0.0.1]) by aserp2120.oracle.com (8.16.0.22/8.16.0.22) with SMTP id w9J0EuGP196100; Fri, 19 Oct 2018 00:17:18 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=oracle.com; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to; s=corp-2018-07-02; bh=Kc7HS7ZmPKGvd9uHoeKA4SzKyl8dMEa9DsakjzTxTFk=; b=eerNa3xlWmu8BxiTluEvM2ab/skkObs+x/ch58Fwfj3ydnOUTWZgDGpiL8PyG+gWhmip V4zIh+TwsbRl3+QYU/lFDD+Z8ynEmjTnwxCz8fhwpWILThDUQFIFeKTG7M+P29A7oAZG mR/eSQwTHR/HRZj1e/CPT9w8kqVKKZWVrc9cHY6z7DsCCgBp+1rEGQgofsXHSRuH3ZZA 708Sw+aITgBNWl4HgltdiBK1213U6nP1w4ihyXQGGM2JqGW9tvLOvr6LQP+8h+rL4aIU gRKI+bPe6NFQrBaLum0fvM2d66ZKvskfS0NMxbamJJ70ERc18C/uPd8PHfEZyGzwGEAO 2w== Received: from userv0022.oracle.com (userv0022.oracle.com [156.151.31.74]) by aserp2120.oracle.com with ESMTP id 2n38nqheq8-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 19 Oct 2018 00:17:18 +0000 Received: from aserv0122.oracle.com (aserv0122.oracle.com [141.146.126.236]) by userv0022.oracle.com (8.14.4/8.14.4) with ESMTP id w9J0HGA3015675 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 19 Oct 2018 00:17:17 GMT Received: from abhmp0018.oracle.com (abhmp0018.oracle.com [141.146.116.24]) by aserv0122.oracle.com (8.14.4/8.14.4) with ESMTP id w9J0HGRI006379; Fri, 19 Oct 2018 00:17:16 GMT Received: from char.us.oracle.com (/10.152.32.25) by default (Oracle Beehive Gateway v4.0) with ESMTP ; Thu, 18 Oct 2018 17:17:16 -0700 Received: by char.us.oracle.com (Postfix, from userid 1000) id 08D4E6A0136; Thu, 18 Oct 2018 20:17:14 -0400 (EDT) Date: Thu, 18 Oct 2018 20:17:14 -0400 From: Konrad Rzeszutek Wilk To: Christoph Hellwig Cc: Will Deacon , Catalin Marinas , Robin Murphy , linux-arm-kernel@lists.infradead.org, iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 03/10] swiotlb: do not panic on mapping failures Message-ID: <20181019001714.GD1251@char.us.oracle.com> References: <20181008080246.20543-1-hch@lst.de> <20181008080246.20543-4-hch@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20181008080246.20543-4-hch@lst.de> User-Agent: Mutt/1.8.3 (2017-05-23) X-Proofpoint-Virus-Version: vendor=nai engine=5900 definitions=9050 signatures=668683 X-Proofpoint-Spam-Details: rule=notspam policy=default score=0 suspectscore=2 malwarescore=0 phishscore=0 bulkscore=0 spamscore=0 mlxscore=0 mlxlogscore=999 adultscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.0.1-1807170000 definitions=main-1810190001 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 08, 2018 at 10:02:39AM +0200, Christoph Hellwig wrote: > All properly written drivers now have error handling in the > dma_map_single / dma_map_page callers. As swiotlb_tbl_map_single already > prints a useful warning when running out of swiotlb pool swace we can s/swace/space/ > also remove swiotlb_full entirely as it serves no purpose now. The panic albeit was useful for those drivers that didn't handle it. Thoughts? I am kind of thinking screw them but then I am not too thrilled about silent data corruption errors. > > Signed-off-by: Christoph Hellwig > --- > kernel/dma/swiotlb.c | 33 +-------------------------------- > 1 file changed, 1 insertion(+), 32 deletions(-) > > diff --git a/kernel/dma/swiotlb.c b/kernel/dma/swiotlb.c > index 26d3af52956f..69bf305ee5f8 100644 > --- a/kernel/dma/swiotlb.c > +++ b/kernel/dma/swiotlb.c > @@ -761,34 +761,6 @@ static bool swiotlb_free_buffer(struct device *dev, size_t size, > return true; > } > > -static void > -swiotlb_full(struct device *dev, size_t size, enum dma_data_direction dir, > - int do_panic) > -{ > - if (swiotlb_force == SWIOTLB_NO_FORCE) > - return; > - > - /* > - * Ran out of IOMMU space for this operation. This is very bad. > - * Unfortunately the drivers cannot handle this operation properly. > - * unless they check for dma_mapping_error (most don't) > - * When the mapping is small enough return a static buffer to limit > - * the damage, or panic when the transfer is too big. > - */ > - dev_err_ratelimited(dev, "DMA: Out of SW-IOMMU space for %zu bytes\n", > - size); > - > - if (size <= io_tlb_overflow || !do_panic) > - return; > - > - if (dir == DMA_BIDIRECTIONAL) > - panic("DMA: Random memory could be DMA accessed\n"); > - if (dir == DMA_FROM_DEVICE) > - panic("DMA: Random memory could be DMA written\n"); > - if (dir == DMA_TO_DEVICE) > - panic("DMA: Random memory could be DMA read\n"); > -} > - > /* > * Map a single buffer of the indicated size for DMA in streaming mode. The > * physical address to use is returned. > @@ -817,10 +789,8 @@ dma_addr_t swiotlb_map_page(struct device *dev, struct page *page, > > /* Oh well, have to allocate and map a bounce buffer. */ > map = map_single(dev, phys, size, dir, attrs); > - if (map == SWIOTLB_MAP_ERROR) { > - swiotlb_full(dev, size, dir, 1); > + if (map == SWIOTLB_MAP_ERROR) > return __phys_to_dma(dev, io_tlb_overflow_buffer); > - } > > dev_addr = __phys_to_dma(dev, map); > > @@ -948,7 +918,6 @@ swiotlb_map_sg_attrs(struct device *hwdev, struct scatterlist *sgl, int nelems, > if (map == SWIOTLB_MAP_ERROR) { > /* Don't panic here, we expect map_sg users > to do proper error handling. */ > - swiotlb_full(hwdev, sg->length, dir, 0); > attrs |= DMA_ATTR_SKIP_CPU_SYNC; > swiotlb_unmap_sg_attrs(hwdev, sgl, i, dir, > attrs); > -- > 2.19.0 >