On Thu, 18 Jul 2019 19:21:20 +0200
Halil Pasic <pasic@linux.ibm.com> wrote:

> On s390 ZONE_DMA is up to 2G, i.e. ARCH_ZONE_DMA_BITS should be 31 bits.
> The current value is 24 and makes __dma_direct_alloc_pages() take a
> wrong turn first (but __dma_direct_alloc_pages() recovers then).
> 
> Let's correct ARCH_ZONE_DMA_BITS value and avoid wrong turns.
> 
> Signed-off-by: Halil Pasic <pasic@linux.ibm.com>
> Reported-by: Petr Tesarik <ptesarik@suse.cz>
> Fixes: c61e9637340e ("dma-direct: add support for allocation from
> ZONE_DMA and ZONE_DMA32")
> ---
>  arch/s390/include/asm/dma.h | 1 +
>  1 file changed, 1 insertion(+)
> 
> diff --git a/arch/s390/include/asm/dma.h b/arch/s390/include/asm/dma.h
> index 6f26f35d4a71..3b0329665b13 100644
> --- a/arch/s390/include/asm/dma.h
> +++ b/arch/s390/include/asm/dma.h
> @@ -10,6 +10,7 @@
>   * by the 31 bit heritage.
>   */
>  #define MAX_DMA_ADDRESS         0x80000000
> +#define ARCH_ZONE_DMA_BITS      31
>  
>  #ifdef CONFIG_PCI
>  extern int isa_dma_bridge_buggy;

Looks good to me.

Petr T