Re: [PATCH 1/2] dma-mapping: check dma_mask for streaming mapping allocs

[Christoph Hellwig]

On Tue, Feb 22, 2022 at 09:41:43PM +0800, Baoquan He wrote:
> For newly added streaming mapping APIs, the internal core function
> __dma_alloc_pages() should check dev->dma_mask, but not
> ev->coherent_dma_mask which is for coherent mapping.

No, this is wrong.  dev->coherent_dma_mask is and should be used here.

>
> 
> Meanwhile, just filter out gfp flags if they are any of
> __GFP_DMA, __GFP_DMA32 and __GFP_HIGHMEM, but not fail it. This change
> makes it  consistent with coherent mapping allocs.

This is wrong as well.  We want to eventually fail dma_alloc_coherent
for these, too.  It just needs more work.