Yes, the iommu is an interesting case, and the current code is wrong for that. 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; +} + static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size, gfp_t gfp) { @@ -68,7 +95,11 @@ static int atomic_pool_expand(struct gen_pool *pool, size_t pool_size, do { pool_size = 1 << (PAGE_SHIFT + order); - page = alloc_pages(gfp, order); + if (cma_in_zone(gfp)) + page = dma_alloc_from_contiguous(NULL, 1 << order, + order, false); + if (!page) + page = alloc_pages(gfp, order); } while (!page && order-- > 0); if (!page) goto out; @@ -251,7 +282,11 @@ void *dma_alloc_from_pool(struct device *dev, size_t size, continue; phys = gen_pool_virt_to_phys(pool, val); - if (dma_coherent_ok(dev, phys, size)) + /* + * Only apply the addressability check for dma-direct. + * This is a nasty hack and won't work e.g. for arm. + */ + if (get_dma_ops(dev) || dma_coherent_ok(dev, phys, size)) break; gen_pool_free(pool, val, size); _______________________________________________ iommu mailing list iommu@lists.linux-foundation.org https://lists.linuxfoundation.org/mailman/listinfo/iommu