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SubjectRE: [PATCH] arm: dma: Drop GFP_COMP for DMA memory allocations
Stephen Warren wrote at Friday, November 04, 2011 3:36 PM:
> dma_alloc_coherent wants to split pages after allocation in order to
> reduce the memory footprint. This does not work well with GFP_COMP
> pages, so drop this flag before allocation.
>
> This patch is ported from arch/avr32
> (commit 3611553ef985ef7c5863c8a94641738addd04cff).
>
> Signed-off-by: Sumit Bhattacharya <sumitb@nvidia.com>
> Tested-by: Varun Colbert <vcolbert@nvidia.com>
> [swarren: s/HUGETLB_PAGE/HUGETLBFS/ in comment, minor comment cleanup]
> Signed-off-by: Stephen Warren <swarren@nvidia.com>

Russell, does this look good to go in the patch system now?

> ---
> arch/arm/mm/dma-mapping.c | 9 +++++++++
> 1 files changed, 9 insertions(+), 0 deletions(-)
>
> diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
> index e4e7f6c..68d64b4 100644
> --- a/arch/arm/mm/dma-mapping.c
> +++ b/arch/arm/mm/dma-mapping.c
> @@ -332,6 +332,15 @@ __dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, gfp_t gfp,
> struct page *page;
> void *addr;
>
> + /*
> + * Following is a work-around (a.k.a. hack) to prevent pages
> + * with __GFP_COMP being passed to split_page() which cannot
> + * handle them. The real problem is that this flag probably
> + * should be 0 on ARM as it is not supported on this
> + * platform; see CONFIG_HUGETLBFS.
> + */
> + gfp &= ~(__GFP_COMP);
> +
> *handle = ~0;
> size = PAGE_ALIGN(size);
>
> --
> 1.7.0.4

--
nvpublic



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