On Mon, Jul 27, 2020 at 07:56:56PM +0200, Nicolas Saenz Julienne wrote: > Hi Christoph, > thanks for having a look at this! > > On Fri, 2020-07-24 at 15:41 +0200, Christoph Hellwig wrote: > > Yes, the iommu is an interesting case, and the current code is > > wrong for that. > > Care to expand on this? I do get that checking dma_coherent_ok() on memory > that'll later on be mapped into an iommu is kind of silly, although I think > harmless in Amir's specific case, since devices have wide enough dma-ranges. > Is > there more to it?
I think the problem is that it can lead to not finding suitable memory. > > > Can you try the patch below? It contains a modified version of Nicolas' > > patch to try CMA again for the expansion and a new (for now hackish) way to > > not apply the addressability check for dma-iommu allocations. > > > > diff --git a/kernel/dma/pool.c b/kernel/dma/pool.c > > index 6bc74a2d51273e..ec5e525d2b9309 100644 > > --- a/kernel/dma/pool.c > > +++ b/kernel/dma/pool.c > > @@ -3,7 +3,9 @@ > > * Copyright (C) 2012 ARM Ltd. > > * Copyright (C) 2020 Google LLC > > */ > > +#include <linux/cma.h> > > #include <linux/debugfs.h> > > +#include <linux/dma-contiguous.h> > > #include <linux/dma-direct.h> > > #include <linux/dma-noncoherent.h> > > #include <linux/init.h> > > @@ -55,6 +57,31 @@ static void dma_atomic_pool_size_add(gfp_t gfp, size_t > > size) > > pool_size_kernel += size; > > } > > > > +static bool cma_in_zone(gfp_t gfp) > > +{ > > + phys_addr_t end; > > + unsigned long size; > > + struct cma *cma; > > + > > + cma = dev_get_cma_area(NULL); > > + if (!cma) > > + return false; > > + > > + size = cma_get_size(cma); > > + if (!size) > > + return false; > > + end = cma_get_base(cma) - memblock_start_of_DRAM() + size - 1; > > + > > + /* CMA can't cross zone boundaries, see cma_activate_area() */ > > + if (IS_ENABLED(CONFIG_ZONE_DMA) && (gfp & GFP_DMA) && > > + end <= DMA_BIT_MASK(zone_dma_bits)) > > + return true; > > + if (IS_ENABLED(CONFIG_ZONE_DMA32) && (gfp & GFP_DMA32) && > > + end <= DMA_BIT_MASK(32)) > > + return true; > > + return true; > > IIUC this will always return true given a CMA is present. Which reverts to the > previous behaviour (previous as in breaking some rpi4 setups), isn't it? Was that really what broke the PI? I'll try to get the split out series today, which might have a few more tweaks, and then we'll need to test it both on these rpi4 setups and Amits phone. _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu