Re: [PATCH v2 1/2] iommu/dma: Respect __GFP_DMA and __GFP_DMA32 in incoming GFP flags

From	Joerg Roedel <joro@8bytes.org>
Newsgroups	linux.kernel
Subject	Re: [PATCH v2 1/2] iommu/dma: Respect __GFP_DMA and __GFP_DMA32 in incoming GFP flags
Date	2017-07-26 11:20 +0200
Message-ID	<u7qE1-6RT-7@gated-at.bofh.it> (permalink)
References	<tZwwV-tH-5@gated-at.bofh.it>
Organization	linux.* mail to news gateway

Show all headers | View raw

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 <tfiga@chromium.org>

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

Back to linux.kernel | Previous | Next — Next in thread | Find similar | Unroll thread

Thread

Re: [PATCH v2 1/2] iommu/dma: Respect __GFP_DMA and __GFP_DMA32 in  incoming GFP flags Joerg Roedel <joro@8bytes.org> - 2017-07-26 11:20 +0200
  Re: [PATCH v2 1/2] iommu/dma: Respect __GFP_DMA and __GFP_DMA32 in  incoming GFP flags Tomasz Figa <tfiga@chromium.org> - 2017-07-26 11:30 +0200

csiph-web