Why does ion_cma_allocate need GFP_HIGHUSER | __GFP_ZERO flags?

[Gioh Kim]

Hi,

I'm wondering why dma_alloc_coherent needs GFP_HIGHUSER | __GFP_ZERO flags in ion_cma_allocate().

I think dma_alloc_coherent can go to __dma_alloc if the system has CMA area.
If __GFP_WAIT flag is set, it allocates memory from atomic pool.
So I think calling dma_alloc_coherent with __GFP_WAIT is enough.

And can I get zero-filled-memory from CMA if I set __GFP_ZERO?


-- 
Thanks,
Gioh Kim
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