From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: [PATCH v2 1/2] iommu/dma: Respect __GFP_DMA and __GFP_DMA32 in incoming GFP flags Date: Wed, 26 Jul 2017 11:15:46 +0200 Message-ID: <20170726091545.GC15833@8bytes.org> References: <20170704135556.21704-1-tfiga@chromium.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20170704135556.21704-1-tfiga@chromium.org> Sender: linux-kernel-owner@vger.kernel.org To: Tomasz Figa Cc: iommu@lists.linux-foundation.org, linux-kernel@vger.kernel.org, Robin Murphy List-Id: iommu@lists.linux-foundation.org On Tue, Jul 04, 2017 at 10:55:55PM +0900, 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. > > Signed-off-by: Tomasz Figa Isn't it better to mask out __GFP_DMA and __GFP_DMA32 in the allocation flags and only take them into account for iova allocation? When the IOMMU re-maps the DMA to this memory it doesn't matter where it is in system memory. Joerg