On Tue, Apr 09, 2024 at 09:17:57AM +0300, Baruch Siach wrote: > Current code using zone_dma_bits assume that all addresses range in the > bits mask are suitable for DMA. For some existing platforms this > assumption is not correct. DMA range might have non zero lower limit. [...] > @@ -59,7 +60,7 @@ static gfp_t dma_direct_optimal_gfp_mask(struct device *dev, u64 *phys_limit) > * zones. > */ > *phys_limit = dma_to_phys(dev, dma_limit); > - if (*phys_limit <= zone_dma_limit) > + if (*phys_limit <= zone_dma_base + zone_dma_limit) > return GFP_DMA; > if (*phys_limit <= DMA_BIT_MASK(32)) > return GFP_DMA32; As I said previously, we no longer have zone_dma_bits after the first patch, so adding this limit no longer make sense. In v1, you wanted a limit like 32G to be added to the 30-bit zone_dma_bits to give you 33G upper limit for ZONE_DMA. But since the first patch sets zone_dma_limit to 33G already, this is no longer needed. -- Catalin
