Re: [PATCH 2/9] dma-direct: reject highmem pages from dma_alloc_from_contiguous
From: Robin Murphy <robin.murphy@arm.com>
Date: 2018-11-30 19:04:57
Also in:
linux-iommu, lkml
On 05/11/2018 12:19, Christoph Hellwig wrote:
dma_alloc_from_contiguous can return highmem pages depending on the setup, which a plain non-remapping DMA allocator can't handle. Detect this case and try the normal page allocator instead.
...except the actual implementation is "Detect this case and fail the entire allocation if so". Again, the diff itself makes sense, so given an accurate commit message, Reviewed-by: Robin Murphy <robin.murphy@arm.com>
quoted hunk ↗ jump to hunk
Signed-off-by: Christoph Hellwig <hch@lst.de> --- kernel/dma/direct.c | 12 ++++++++++++ 1 file changed, 12 insertions(+)diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c index 680287779b0a..c49849bcced6 100644 --- a/kernel/dma/direct.c +++ b/kernel/dma/direct.c@@ -162,6 +162,18 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size, if (!page) return NULL; + if (PageHighMem(page)) { + /* + * Depending on the cma= arguments and per-arch setup + * dma_alloc_from_contiguous could return highmem pages. + * Without remapping there is no way to return them here, + * so log an error and fail. + */ + dev_info(dev, "Rejecting highmem page from CMA.\n"); + __dma_direct_free_pages(dev, size, page); + return NULL; + } + ret = page_address(page); if (force_dma_unencrypted()) { set_memory_decrypted((unsigned long)ret, 1 << get_order(size));
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