On Thu, 18 Jul 2019 06:10:59 -0700 Christoph Hellwig <hch@xxxxxxxxxxxxx> wrote: > On Thu, Jul 18, 2019 at 02:50:44PM +0200, Halil Pasic wrote: > > > I wondered why the kernel works OK on my system, and it is in fact not > > > so bad. If the first allocation fails, the kernel adds GFP_DMA and > > > retries, so this is not fatal, but with a proper definition of > > > ARCH_ZONE_DMA_BITS it should be possible to get success in the first > > > attempt already, let's do it. > > > > > > Petr T > > > > I fully agree! I will post a patch that provides correct > > ARCH_ZONE_DMA_BITS for s390. > > > > BTW I wonder if ARCH_ZONE_DMA_BITS can be inferred from MAX_DMA_ADDRESS, > > and why do we need both.@Christoph, maybe you can help me understand if > > there is a relationship between the two or not, or? > > MAX_DMA_ADDRESS is a bit of a weird beast which I honestly do not > understand fully, but most of the uses in common code look a little > bogus, and we should probably get rid of it. Thanks! Regards, Halil
