[PATCH] drm/ttm: properly unmap dma page upon failure

[Yu Zhao]

Probably my previous emails went into the spam folder. Another friendly
reminder using web version of my Gmail. Thank you.

On Mon, Mar 25, 2019 at 2:22 PM Yu Zhao <yuzhao at google.com> wrote:

> dma_unmap_page() must be called with exactly the same dma address
> and size returned by dma_map_page(). Otherwise, the function may
> fail.
>
> This is at least the case for debug_dma_unmap_page() and AMD iommu
> unmap_page callback.
>
> Signed-off-by: Yu Zhao <yuzhao at google.com>
> ---
>  drivers/gpu/drm/ttm/ttm_page_alloc.c | 11 ++++++++++-
>  1 file changed, 10 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/ttm/ttm_page_alloc.c
> b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> index f841accc2c00..c1636595f63c 100644
> --- a/drivers/gpu/drm/ttm/ttm_page_alloc.c
> +++ b/drivers/gpu/drm/ttm/ttm_page_alloc.c
> @@ -1118,10 +1118,19 @@ int ttm_populate_and_map_pages(struct device *dev,
> struct ttm_dma_tt *tt,
>                                                   0, num_pages * PAGE_SIZE,
>                                                   DMA_BIDIRECTIONAL);
>                 if (dma_mapping_error(dev, tt->dma_address[i])) {
> +                       num_pages = 1;
>                         while (i--) {
> +                               if (i && tt->ttm.pages[i] -
> +                                        tt->ttm.pages[i - 1] == 1) {
> +                                       tt->dma_address[i] = 0;
> +                                       num_pages++;
> +                                       continue;
> +                               }
>                                 dma_unmap_page(dev, tt->dma_address[i],
> -                                              PAGE_SIZE,
> DMA_BIDIRECTIONAL);
> +                                              num_pages * PAGE_SIZE,
> +                                              DMA_BIDIRECTIONAL);
>                                 tt->dma_address[i] = 0;
> +                               num_pages = 1;
>                         }
>                         ttm_pool_unpopulate(&tt->ttm);
>                         return -EFAULT;
> --
> 2.21.0.392.gf8f6787159e-goog
>
>
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