| Message ID | 1381918756-10389-1-git-send-email-hdoyu@nvidia.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
On Wed, Oct 16, 2013 at 11:19:13AM +0100, Hiroshi Doyu wrote: > arm_iommu_alloc_attrs 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. > > ref: ea2e7057c0234cfb8b09467d8f137760d371fc72: > > ARM: 7172/1: dma: Drop GFP_COMP for DMA memory allocations > > 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. > > Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com> > --- > arch/arm/mm/dma-mapping.c | 7 +++++++ > 1 file changed, 7 insertions(+) > > diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c > index f5e1a84..955dd3e 100644 > --- a/arch/arm/mm/dma-mapping.c > +++ b/arch/arm/mm/dma-mapping.c > @@ -1321,6 +1321,13 @@ static void *arm_iommu_alloc_attrs(struct device *dev, size_t size, > struct page **pages; > void *addr = NULL; > > + /* 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_HUGETLB_PAGE. */ > + gfp &= ~(__GFP_COMP); Right, except that we *do* have hugepage support on ARM, so this probably needs fixing properly. Will
diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index f5e1a84..955dd3e 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -1321,6 +1321,13 @@ static void *arm_iommu_alloc_attrs(struct device *dev, size_t size, struct page **pages; void *addr = NULL; + /* 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_HUGETLB_PAGE. */ + gfp &= ~(__GFP_COMP); + *handle = DMA_ERROR_CODE; size = PAGE_ALIGN(size);
arm_iommu_alloc_attrs 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. ref: ea2e7057c0234cfb8b09467d8f137760d371fc72: ARM: 7172/1: dma: Drop GFP_COMP for DMA memory allocations 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. Signed-off-by: Hiroshi Doyu <hdoyu@nvidia.com> --- arch/arm/mm/dma-mapping.c | 7 +++++++ 1 file changed, 7 insertions(+)