Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752903AbdF0LBk (ORCPT ); Tue, 27 Jun 2017 07:01:40 -0400 Received: from foss.arm.com ([217.140.101.70]:55288 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752707AbdF0LBZ (ORCPT ); Tue, 27 Jun 2017 07:01:25 -0400 Subject: Re: [PATCH 1/2] iommu/dma: Respect __GFP_DMA and __GFP_DMA32 in incoming GFP flags To: Tomasz Figa , iommu@lists.linux-foundation.org Cc: linux-kernel@vger.kernel.org, Joerg Roedel References: <20170627072812.15316-1-tfiga@chromium.org> From: Robin Murphy Message-ID: Date: Tue, 27 Jun 2017 12:01:21 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:52.0) Gecko/20100101 Thunderbird/52.1.1 MIME-Version: 1.0 In-Reply-To: <20170627072812.15316-1-tfiga@chromium.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1503 Lines: 42 On 27/06/17 08:28, Tomasz Figa wrote: > Current implementation of __iommu_dma_alloc_pages() keeps adding > __GFP_HIGHMEM to GFP flags regardless of whether other zone flags are > already included in the incoming flags. If __GFP_DMA or __GFP_DMA32 is > set at the same time as __GFP_HIGHMEM, the allocation fails due to > invalid zone flag combination. > > Fix this by checking for __GFP_DMA and __GFP_DMA32 in incoming GFP flags > and adding __GFP_HIGHMEM only if they are not present. Wouldn't it make more sense to strip off the ZONE_DMA* related flags, since the whole point here is that we don't care where the pages come from? Robin. > Signed-off-by: Tomasz Figa > --- > drivers/iommu/dma-iommu.c | 10 ++++++++-- > 1 file changed, 8 insertions(+), 2 deletions(-) > > diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c > index 9d1cebe7f6cb..29965a092a69 100644 > --- a/drivers/iommu/dma-iommu.c > +++ b/drivers/iommu/dma-iommu.c > @@ -445,8 +445,14 @@ static struct page **__iommu_dma_alloc_pages(unsigned int count, > if (!pages) > return NULL; > > - /* IOMMU can map any pages, so himem can also be used here */ > - gfp |= __GFP_NOWARN | __GFP_HIGHMEM; > + /* > + * IOMMU can map any pages, so himem can also be used here, > + * unless another DMA zone is explicitly requested. > + */ > + if (!(gfp & (__GFP_DMA | __GFP_DMA32))) > + gfp |= __GFP_HIGHMEM; > + > + gfp |= __GFP_NOWARN; > > while (count) { > struct page *page = NULL; >