On Tue, Jul 07, 2020 at 02:28:04PM +0200, Nicolas Saenz Julienne wrote:
> When allocating atomic DMA memory for a device, the dma-pool core
> queries __dma_direct_optimal_gfp_mask() to check which atomic pool to
> use. It turns out the GFP flag returned is only an optimistic guess.
> The pool selected might sometimes live in a zone higher than the
> device's view of memory.
>
> As there isn't a way to grantee a mapping between a device's DMA
> constraints and correct GFP flags this unifies both DMA atomic pools.
> The resulting pool is allocated in the lower DMA zone available, if any,
> so as for devices to always get accessible memory while having the
> flexibility of using dma_pool_kernel for the non constrained ones.
>
> Fixes: c84dc6e68a1d ("dma-pool: add additional coherent pools to map to gfp
> mask")
> Reported-by: Jeremy Linton <[email protected]>
> Suggested-by: Robin Murphy <[email protected]>
> Signed-off-by: Nicolas Saenz Julienne <[email protected]>
Hmm, this is not what I expected from the previous thread. I thought
we'd just use one dma pool based on runtime available of the zones..
