From: Mike Rapoport <rppt@xxxxxxxxxxxxx> [ Upstream commit a9c38c5d267cb94871dfa2de5539c92025c855d7 ] dma_map_resource() uses pfn_valid() to ensure the range is not RAM. However, pfn_valid() only checks for availability of the memory map for a PFN but it does not ensure that the PFN is actually backed by RAM. As dma_map_resource() is the only method in DMA mapping APIs that has this check, simply drop the pfn_valid() test from dma_map_resource(). Link: https://lore.kernel.org/all/20210824173741.GC623@xxxxxxx/ Signed-off-by: Mike Rapoport <rppt@xxxxxxxxxxxxx> Reviewed-by: Christoph Hellwig <hch@xxxxxx> Acked-by: David Hildenbrand <david@xxxxxxxxxx> Link: https://lore.kernel.org/r/20210930013039.11260-2-rppt@xxxxxxxxxx Signed-off-by: Will Deacon <will@xxxxxxxxxx> Fixes: 859a85ddf90e ("mm: remove pfn_valid_within() and CONFIG_HOLES_IN_ZONE") Link: https://lore.kernel.org/r/Yl0IZWT2nsiYtqBT@xxxxxxxxxxxxx Signed-off-by: Georgi Djakov <quic_c_gdjako@xxxxxxxxxxx> --- kernel/dma/mapping.c | 4 ---- 1 file changed, 4 deletions(-) diff --git a/kernel/dma/mapping.c b/kernel/dma/mapping.c index 8349a9f2c345..9478eccd1c8e 100644 --- a/kernel/dma/mapping.c +++ b/kernel/dma/mapping.c @@ -296,10 +296,6 @@ dma_addr_t dma_map_resource(struct device *dev, phys_addr_t phys_addr, if (WARN_ON_ONCE(!dev->dma_mask)) return DMA_MAPPING_ERROR; - /* Don't allow RAM to be mapped */ - if (WARN_ON_ONCE(pfn_valid(PHYS_PFN(phys_addr)))) - return DMA_MAPPING_ERROR; - if (dma_map_direct(dev, ops)) addr = dma_direct_map_resource(dev, phys_addr, size, dir, attrs); else if (ops->map_resource)
