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 <[email protected]>
Signed-off-by: Christoph Hellwig <[email protected]>
---
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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