Re: [PATCH] ARM: dma-mapping: always clear allocated buffers

[Christoph Hellwig]

On Tue, Jul 24, 2018 at 10:04:35PM +0800, YueHaibing wrote:
> Sean Wang report dma_zalloc_coherent doesn't work as expect on his
> armv7,the allocated mem is not zeroed.The reason is __alloc_from_pool
> doesn't honor __GFP_ZERO.

Please explain the "why" a little more.  All the explanations are in
the referenced arm64 commit and should be mentioned here as well.