From 704f2c20eaa566f6906e8812b6e2115889bd753d Mon Sep 17 00:00:00 2001
From: Christoph Hellwig <hch@lst.de>
Date: Sat, 22 Sep 2018 20:47:26 +0200
Subject: [PATCH] dma-direct: reject highmem pages from
dma_alloc_from_contiguous
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 fail the allocation.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Robin Murphy <robin.murphy@arm.com>
---
kernel/dma/direct.c | 12 ++++++++++++
1 file changed, 12 insertions(+)
diff --git a/kernel/dma/direct.c b/kernel/dma/direct.c
index 680287779b0ad2..c49849bcced6a3 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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