Messages in this thread |  | | Date | Tue, 2 Nov 2021 07:41:55 +0100 | From | Christoph Hellwig <> | Subject | Re: [PATCH] dma-direct: fix DMA_ATTR_NO_KERNEL_MAPPING |
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As others pointed out, DMA_ATTR_NO_KERNEL_MAPPING just means the caller can't rely on a kernel mapping. So the "fix" here is wrong. That being said for cases where we can easily remove a page from the kernel mapping it would be nice to do to:
a) improve security b) as a debug check to see that no one actually tries to access it
> + /* remove kernel mapping for pages */ > + set_memory_valid((unsigned long)phys_to_virt(dma_to_phys(dev, *dma_handle)),
Please avoid overly long lines. Also this function only exists for arm64 also and others pointed out won't work for all cases.
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