dma_alloc_contiguous
page = dma_alloc_contiguous(dev, alloc_size, gfp);
struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp);
page = dma_alloc_contiguous(dev, size, gfp);
page = dma_alloc_contiguous(dev, size, gfp);