Hi.
vzalloc() call in __iommu_alloc_buffer() also causes BUG() in atomic context.
On Wed, Aug 22, 2012 at 7:20 PM, Hiroshi Doyu <hdoyu@nvidia.com> wrote:
> 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 <hdoyu@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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