On Wed, Jul 31, 2019 at 05:47:48PM +0200, Nicolas Saenz Julienne wrote: > diff --git a/arch/arm64/mm/init.c b/arch/arm64/mm/init.c > index 1c4ffabbe1cb..f5279ef85756 100644 > --- a/arch/arm64/mm/init.c > +++ b/arch/arm64/mm/init.c > @@ -50,6 +50,13 @@ > s64 memstart_addr __ro_after_init = -1; > EXPORT_SYMBOL(memstart_addr); > > +/* > + * We might create both a ZONE_DMA and ZONE_DMA32. ZONE_DMA is needed if there > + * are periferals unable to address the first naturally aligned 4GB of ram. > + * ZONE_DMA32 will be expanded to cover the rest of that memory. If such > + * limitations doesn't exist only ZONE_DMA32 is created. > + */ Shouldn't we instead only create ZONE_DMA to cover the whole 32-bit range and leave ZONE_DMA32 empty? Can__GFP_DMA allocations fall back onto ZONE_DMA32? -- Catalin
