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Subject[PATCH] dma-direct: reject highmem pages from dma_alloc_from_contiguous
Date
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.

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 87a6bc2a96c0..46fbaa49125b 100644
--- a/kernel/dma/direct.c
+++ b/kernel/dma/direct.c
@@ -126,6 +126,18 @@ void *dma_direct_alloc_pages(struct device *dev, size_t size,
if (gfpflags_allow_blocking(gfp)) {
page = dma_alloc_from_contiguous(dev, count, page_order,
gfp & __GFP_NOWARN);
+ if (page && 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, "Ignoring highmem page from CMA.\n");
+ dma_release_from_contiguous(dev, page, count);
+ page = NULL;
+ }
+
if (page && !dma_coherent_ok(dev, page_to_phys(page), size)) {
dma_release_from_contiguous(dev, page, count);
page = NULL;
--
2.19.1
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