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=-8.2 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=unavailable 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 1ABF5C76191 for ; Fri, 26 Jul 2019 06:28:56 +0000 (UTC) Received: from mail.linuxfoundation.org (mail.linuxfoundation.org [140.211.169.12]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPS id F168D218DA for ; Fri, 26 Jul 2019 06:28:55 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org F168D218DA Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=lst.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=iommu-bounces@lists.linux-foundation.org Received: from mail.linux-foundation.org (localhost [127.0.0.1]) by mail.linuxfoundation.org (Postfix) with ESMTP id 990BEB5F; Fri, 26 Jul 2019 06:28:55 +0000 (UTC) Received: from smtp1.linuxfoundation.org (smtp1.linux-foundation.org [172.17.192.35]) by mail.linuxfoundation.org (Postfix) with ESMTPS id 813F03EE for ; Fri, 26 Jul 2019 06:28:54 +0000 (UTC) X-Greylist: from auto-whitelisted by SQLgrey-1.7.6 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) by smtp1.linuxfoundation.org (Postfix) with ESMTPS id CE28F709 for ; Fri, 26 Jul 2019 06:28:53 +0000 (UTC) Received: by verein.lst.de (Postfix, from userid 2407) id CA18068B02; Fri, 26 Jul 2019 08:28:49 +0200 (CEST) Date: Fri, 26 Jul 2019 08:28:49 +0200 From: Christoph Hellwig To: Nicolin Chen Subject: Re: [PATCH 1/2] dma-contiguous: do not overwrite align in dma_alloc_contiguous() Message-ID: <20190726062849.GE22881@lst.de> References: <20190725233959.15129-1-nicoleotsuka@gmail.com> <20190725233959.15129-2-nicoleotsuka@gmail.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20190725233959.15129-2-nicoleotsuka@gmail.com> User-Agent: Mutt/1.5.17 (2007-11-01) Cc: dafna.hirschfeld@collabora.com, linux-kernel@vger.kernel.org, iommu@lists.linux-foundation.org, robin.murphy@arm.com, hch@lst.de X-BeenThere: iommu@lists.linux-foundation.org X-Mailman-Version: 2.1.12 Precedence: list List-Id: Development issues for Linux IOMMU support List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: iommu-bounces@lists.linux-foundation.org Errors-To: iommu-bounces@lists.linux-foundation.org On Thu, Jul 25, 2019 at 04:39:58PM -0700, Nicolin Chen wrote: > The dma_alloc_contiguous() limits align at CONFIG_CMA_ALIGNMENT for > cma_alloc() however it does not restore it for the fallback routine. > This will result in a size mismatch between the allocation and free > when running in the fallback routines, if the align is larger than > CONFIG_CMA_ALIGNMENT. > > This patch adds a cma_align to take care of cma_alloc() and prevent > the align from being overwritten. > > Fixes: fdaeec198ada ("dma-contiguous: add dma_{alloc,free}_contiguous() helpers") > Reported-by: Dafna Hirschfeld > Signed-off-by: Nicolin Chen > --- > kernel/dma/contiguous.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c > index bfc0c17f2a3d..fa8cd0f0512e 100644 > --- a/kernel/dma/contiguous.c > +++ b/kernel/dma/contiguous.c > @@ -233,6 +233,7 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) > int node = dev ? dev_to_node(dev) : NUMA_NO_NODE; > size_t count = PAGE_ALIGN(size) >> PAGE_SHIFT; > size_t align = get_order(PAGE_ALIGN(size)); > + size_t cma_align = CONFIG_CMA_ALIGNMENT; > struct page *page = NULL; > struct cma *cma = NULL; > > @@ -241,11 +242,11 @@ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) > else if (count > 1) > cma = dma_contiguous_default_area; > > + cma_align = min_t(size_t, align, cma_align); > + > /* CMA can be used only in the context which permits sleeping */ > - if (cma && gfpflags_allow_blocking(gfp)) { > - align = min_t(size_t, align, CONFIG_CMA_ALIGNMENT); > - page = cma_alloc(cma, count, align, gfp & __GFP_NOWARN); > - } > + if (cma && gfpflags_allow_blocking(gfp)) > + page = cma_alloc(cma, count, cma_align, gfp & __GFP_NOWARN); Shouldn't cma_align be confined to the block guarded by "if (cma && gfpflags_allow_blocking(gfp))" so that we can optimize it away for configurations that do not support CMA? _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu