Re: [PATCH] swiotlb: use coherent_dma_mask in alloc_coherent

[Ingo Molnar]

* FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx> wrote:

> This patch fixes swiotlb to use dev->coherent_dma_mask in 
> alloc_coherent. Currently, swiotlb uses dev->dma_mask in 
> alloc_coherent but alloc_coherent is supposed to use 
> coherent_dma_mask. It could break drivers that uses smaller 
> coherent_dma_mask than dma_mask (though the current code works for 
> the majority that use the same mask for coherent_dma_mask and 
> dma_mask).
> 
> Signed-off-by: FUJITA Tomonori <fujita.tomonori@xxxxxxxxxxxxx>
> ---
>  lib/swiotlb.c |   10 +++++++---
>  1 files changed, 7 insertions(+), 3 deletions(-)

Applied it with the changelog below to tip/core/urgent, thanks!

I also flagged it for v2.6.28 inclusion. This bug was caused by the 
removal of the GFP_DMA hack in swiotlb_alloc_coherent() in this cycle. 
I havent seen it actually reported anywhere - have you perhaps?Or have 
you found this via code review?

Do we know roughly the range of devices/systems where there's a real 
address range that cannot be DMA-ed to coherently, and an estimation 
about how frequently they would be affected by this bug?

	Ingo

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