Re: [PATCH] dma-pool: use single atomic pool for both DMA zones

[Christoph Hellwig]

On Wed, Jul 08, 2020 at 12:35:34PM +0200, Nicolas Saenz Julienne wrote:
> > Which allows me to switch between ACPI/DT on the machine. In DT mode it 
> > works fine now, 
> 
> Nice, would that count as a Tested-by from you?
> 
> > but with ACPI I continue to have failures unless I 
> > disable CMA via cma=0 on the kernel command line. 
> 
> Yes, I see why, in atomic_pool_expand() memory is allocated from CMA without
> checking its correctness. That calls for a separate fix. I'll try to think of
> something.

I think we need a dma_coherent_ok for the allocations from the
pool and then fall back to the next better one to get started.  And
yes, CMA is a bit of a mess, that generally needs better checks.