From 5b91a98c61abe914e6a80d7dc15e435c47ea0004 Mon Sep 17 00:00:00 2001 From: Richard Zhao Date: Thu, 20 Jun 2013 20:31:00 +0800 Subject: [PATCH] ARM: dma: Drop __GFP_COMP for iommu dma memory allocations __iommu_alloc_buffer 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 One failure example is snd_malloc_dev_pages call dma_alloc_coherent with __GFP_COMP. Signed-off-by: Richard Zhao Signed-off-by: Marek Szyprowski --- arch/arm/mm/dma-mapping.c | 9 +++++++++ 1 file changed, 9 insertions(+) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 97926b1..22c7d7e 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -1328,6 +1328,15 @@ static void *arm_iommu_alloc_attrs(struct device *dev, size_t size, if (gfp & GFP_ATOMIC) return __iommu_alloc_atomic(dev, size, handle); + /* + * 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); + pages = __iommu_alloc_buffer(dev, size, gfp, attrs); if (!pages) return NULL; -- 2.7.4