Makes use of the same atomic pool from DMA, and skips kernel page
mapping which can involves sleep'able operation at allocating a kernel
page table.

Signed-off-by: Hiroshi Doyu <hd...@nvidia.com>
---
 arch/arm/mm/dma-mapping.c |   22 ++++++++++++++++++----
 1 files changed, 18 insertions(+), 4 deletions(-)

diff --git a/arch/arm/mm/dma-mapping.c b/arch/arm/mm/dma-mapping.c
index aec0c06..9260107 100644
--- a/arch/arm/mm/dma-mapping.c
+++ b/arch/arm/mm/dma-mapping.c
@@ -1028,7 +1028,6 @@ static struct page **__iommu_alloc_buffer(struct device 
*dev, size_t size,
        struct page **pages;
        int count = size >> PAGE_SHIFT;
        int array_size = count * sizeof(struct page *);
-       int err;
 
        if (array_size <= PAGE_SIZE)
                pages = kzalloc(array_size, gfp);
@@ -1037,9 +1036,20 @@ static struct page **__iommu_alloc_buffer(struct device 
*dev, size_t size,
        if (!pages)
                return NULL;
 
-       err = __alloc_fill_pages(&pages, count, gfp);
-       if (err)
-               goto error
+       if (gfp & GFP_ATOMIC) {
+               struct page *page;
+               int i;
+               void *addr = __alloc_from_pool(size, &page);
+               if (!addr)
+                       goto err_out;
+
+               for (i = 0; i < count; i++)
+                       pages[i] = page + i;
+       } else {
+               int err = __alloc_fill_pages(&pages, count, gfp);
+               if (err)
+                       goto error;
+       }
 
        return pages;
 error:
@@ -1055,6 +1065,10 @@ static int __iommu_free_buffer(struct device *dev, 
struct page **pages, size_t s
        int count = size >> PAGE_SHIFT;
        int array_size = count * sizeof(struct page *);
        int i;
+
+       if (__free_from_pool(page_address(pages[0]), size))
+               return 0;
+
        for (i = 0; i < count; i++)
                if (pages[i])
                        __free_pages(pages[i], 0);
-- 
1.7.5.4

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