diff options
| -rw-r--r-- | kernel/dma/contiguous.c | 11 |
1 files changed, 10 insertions, 1 deletions
diff --git a/kernel/dma/contiguous.c b/kernel/dma/contiguous.c index 637b120d647b..bfc0c17f2a3d 100644 --- a/kernel/dma/contiguous.c +++ b/kernel/dma/contiguous.c @@ -223,14 +223,23 @@ bool dma_release_from_contiguous(struct device *dev, struct page *pages, * This function allocates contiguous memory buffer for specified device. It * first tries to use device specific contiguous memory area if available or * the default global one, then tries a fallback allocation of normal pages. + * + * Note that it byapss one-page size of allocations from the global area as + * the addresses within one page are always contiguous, so there is no need + * to waste CMA pages for that kind; it also helps reduce fragmentations. */ struct page *dma_alloc_contiguous(struct device *dev, size_t size, gfp_t gfp) { int node = dev ? dev_to_node(dev) : NUMA_NO_NODE; size_t count = PAGE_ALIGN(size) >> PAGE_SHIFT; size_t align = get_order(PAGE_ALIGN(size)); - struct cma *cma = dev_get_cma_area(dev); struct page *page = NULL; + struct cma *cma = NULL; + + if (dev && dev->cma_area) + cma = dev->cma_area; + else if (count > 1) + cma = dma_contiguous_default_area; /* CMA can be used only in the context which permits sleeping */ if (cma && gfpflags_allow_blocking(gfp)) { |