On 27/06/17 08:28, Tomasz Figa wrote:
> Current implementation of __iommu_dma_alloc_pages() keeps adding
> __GFP_HIGHMEM to GFP flags regardless of whether other zone flags are
> already included in the incoming flags. If __GFP_DMA or __GFP_DMA32 is
> set at the same time as __GFP_HIGHMEM, the allocation fails due to
> invalid zone flag combination.
>
> Fix this by checking for __GFP_DMA and __GFP_DMA32 in incoming GFP flags
> and adding __GFP_HIGHMEM only if they are not present.
Wouldn't it make more sense to strip off the ZONE_DMA* related flags,
since the whole point here is that we don't care where the pages come from?
Robin.
> Signed-off-by: Tomasz Figa <tf...@chromium.org>
> ---
> drivers/iommu/dma-iommu.c | 10 ++++++++--
> 1 file changed, 8 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/iommu/dma-iommu.c b/drivers/iommu/dma-iommu.c
> index 9d1cebe7f6cb..29965a092a69 100644
> --- a/drivers/iommu/dma-iommu.c
> +++ b/drivers/iommu/dma-iommu.c
> @@ -445,8 +445,14 @@ static struct page **__iommu_dma_alloc_pages(unsigned
> int count,
> if (!pages)
> return NULL;
>
> - /* IOMMU can map any pages, so himem can also be used here */
> - gfp |= __GFP_NOWARN | __GFP_HIGHMEM;
> + /*
> + * IOMMU can map any pages, so himem can also be used here,
> + * unless another DMA zone is explicitly requested.
> + */
> + if (!(gfp & (__GFP_DMA | __GFP_DMA32)))
> + gfp |= __GFP_HIGHMEM;
> +
> + gfp |= __GFP_NOWARN;
>
> while (count) {
> struct page *page = NULL;
>
