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The dma_alloc_coherent() function returns a virtual address which can be used for coherent access to the underlying memory. On some architectures, like arm64, undefined behavior results if this memory is also accessed via virtual mappings that are not coherent. Because of their undefined nature, operations like virt_to_page() return garbage when passed virtual addresses obtained from dma_alloc_coherent(). Any subsequent mappings via vmap() of the garbage page values are unusable and result in bad things like bus errors (synchronous aborts in ARM64 speak). The mlx4 driver contains code that does the equivalent of: vmap(virt_to_page(dma_alloc_coherent)), this results in an OOPs when the device is opened. Prevent Ethernet driver to run this problematic code by forcing it to allocate contiguous memory. As for the Infiniband driver, at first we are trying to allocate contiguous memory, but in case of failure roll back to work with fragmented memory. Signed-off-by: Haggai Abramovsky <hagaya@mellanox.com> Signed-off-by: Yishai Hadas <yishaih@mellanox.com> Reported-by: David Daney <david.daney@cavium.com> Tested-by: Sinan Kaya <okaya@codeaurora.org> Signed-off-by: David S. Miller <davem@davemloft.net> |
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