Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754800AbeAJJc1 (ORCPT + 1 other); Wed, 10 Jan 2018 04:32:27 -0500 Received: from usa-sjc-mx-foss1.foss.arm.com ([217.140.101.70]:38682 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754096AbeAJJcW (ORCPT ); Wed, 10 Jan 2018 04:32:22 -0500 Subject: Re: [PATCH 29/33] dma-direct: retry allocations using GFP_DMA for small masks To: Christoph Hellwig , iommu@lists.linux-foundation.org Cc: linux-mips@linux-mips.org, linux-ia64@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, Guan Xuetao , linux-arch@vger.kernel.org, linux-s390@vger.kernel.org, linux-c6x-dev@linux-c6x.org, linux-hexagon@vger.kernel.org, x86@kernel.org, Konrad Rzeszutek Wilk , linux-snps-arc@lists.infradead.org, linux-m68k@lists.linux-m68k.org, patches@groups.riscv.org, linux-metag@vger.kernel.org, linux-arm-kernel@lists.infradead.org, Michal Simek , linux-parisc@vger.kernel.org, linux-cris-kernel@axis.com, linux-kernel@vger.kernel.org, linux-alpha@vger.kernel.org, linuxppc-dev@lists.ozlabs.org References: <20180110080027.13879-1-hch@lst.de> <20180110080027.13879-30-hch@lst.de> From: Vladimir Murzin Message-ID: <93966313-cc79-8173-48e6-157caa443322@arm.com> Date: Wed, 10 Jan 2018 09:32:16 +0000 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.2.1 MIME-Version: 1.0 In-Reply-To: <20180110080027.13879-30-hch@lst.de> Content-Type: text/plain; charset=utf-8 Content-Language: en-GB Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Return-Path: On 10/01/18 08:00, Christoph Hellwig wrote: > If an attempt to allocate memory succeeded, but isn't inside the > supported DMA mask, retry the allocation with GFP_DMA set as a > last resort. > > Based on the x86 code, but an off by one error in what is now > dma_coherent_ok has been fixed vs the x86 code. > > Signed-off-by: Christoph Hellwig > --- > lib/dma-direct.c | 25 ++++++++++++++++++++++++- > 1 file changed, 24 insertions(+), 1 deletion(-) > > diff --git a/lib/dma-direct.c b/lib/dma-direct.c > index 8f76032ebc3c..4e43c2bb7f5f 100644 > --- a/lib/dma-direct.c > +++ b/lib/dma-direct.c > @@ -35,6 +35,11 @@ check_addr(struct device *dev, dma_addr_t dma_addr, size_t size, > return true; > } > > +static bool dma_coherent_ok(struct device *dev, phys_addr_t phys, size_t size) > +{ > + return phys_to_dma(dev, phys) + size - 1 <= dev->coherent_dma_mask; > +} > + > static void *dma_direct_alloc(struct device *dev, size_t size, > dma_addr_t *dma_handle, gfp_t gfp, unsigned long attrs) > { > @@ -48,11 +53,29 @@ static void *dma_direct_alloc(struct device *dev, size_t size, > if (dev->coherent_dma_mask <= DMA_BIT_MASK(32) && !(gfp & GFP_DMA)) > gfp |= GFP_DMA32; > > +again: > /* CMA can be used only in the context which permits sleeping */ > - if (gfpflags_allow_blocking(gfp)) > + if (gfpflags_allow_blocking(gfp)) { > page = dma_alloc_from_contiguous(dev, count, page_order, gfp); > + if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) { > + dma_release_from_contiguous(dev, page, count); > + page = NULL; > + } > + } > if (!page) > page = alloc_pages_node(dev_to_node(dev), gfp, page_order); > + > + if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) { > + __free_pages(page, page_order); > + page = NULL; > + > + if (dev->coherent_dma_mask < DMA_BIT_MASK(32) && > + !(gfp & GFP_DMA)) { > + gfp = (gfp & ~GFP_DMA32) | GFP_DMA; > + goto again; > + } > + } > + > if (!page) > return NULL; > > Reviewed-by: Vladimir Murzin Cheers Vladimir