Lift the code to clear __GFP_COMP from arm into the common DMA allocator path. For one this fixes the various other patches that call alloc_pages_exact or split_page in case a bogus driver passes the argument, and it also prepares for doing exact allocation in the generic dma-direct allocator. Signed-off-by: Christoph Hellwig <hch@xxxxxx> --- arch/arm/mm/dma-mapping.c | 17 ----------------- kernel/dma/mapping.c | 9 +++++++++ 2 files changed, 9 insertions(+), 17 deletions(-) diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c index 0a75058c11f3..86135feb2c05 100644 --- a/arch/arm/mm/dma-mapping.c +++ b/arch/arm/mm/dma-mapping.c @@ -759,14 +759,6 @@ static void *__dma_alloc(struct device *dev, size_t size, dma_addr_t *handle, if (mask < 0xffffffffULL) gfp |= GFP_DMA; - /* - * 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); args.gfp = gfp; *handle = DMA_MAPPING_ERROR; @@ -1527,15 +1519,6 @@ static void *__arm_iommu_alloc_attrs(struct device *dev, size_t size, return __iommu_alloc_simple(dev, size, gfp, handle, coherent_flag, attrs); - /* - * 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, coherent_flag); if (!pages) return NULL; diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index f7afdadb6770..4b618e1abbc1 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -252,6 +252,15 @@ void *dma_alloc_attrs(struct device *dev, size_t size, dma_addr_t *dma_handle, /* let the implementation decide on the zone to allocate from: */ flag &= ~(__GFP_DMA | __GFP_DMA32 | __GFP_HIGHMEM); + /* + * __GFP_COMP interacts badly with splitting up a larger order + * allocation. But as our allocations might not even come from the + * page allocator, the callers can't rely on the fact that they + * even get pages, never mind which kind. + */ + if (WARN_ON_ONCE(flag & __GFP_COMP)) + flag &= ~__GFP_COMP; + if (dma_is_direct(ops)) cpu_addr = dma_direct_alloc(dev, size, dma_handle, flag, attrs); else if (ops->alloc) -- 2.20.1
