Messages in this thread | | | Date | Wed, 8 Jul 2020 17:35:09 +0200 | From | Christoph Hellwig <> | Subject | Re: [PATCH] dma-pool: use single atomic pool for both DMA zones |
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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 <jeremy.linton@arm.com> > Suggested-by: Robin Murphy <robin.murphy@arm.com> > Signed-off-by: Nicolas Saenz Julienne <nsaenzjulienne@suse.de>
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..
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