[PATCH] scatterlist: add a warning if sg_virt() is used on highmem pages

[Sebastian Andrzej Siewior]

sg_virt() on highmem pages won't work. This WARN_ON() should catch some
that still try.

Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
---
 include/linux/scatterlist.h |    3 +++
 1 file changed, 3 insertions(+)

diff --git a/include/linux/scatterlist.h b/include/linux/scatterlist.h
index 4bd6c06..4d4adab 100644
--- a/include/linux/scatterlist.h
+++ b/include/linux/scatterlist.h
@@ -198,6 +198,9 @@ static inline dma_addr_t sg_phys(struct scatterlist *sg)
  **/
 static inline void *sg_virt(struct scatterlist *sg)
 {
+#ifdef CONFIG_DEBUG_SG
+	WARN_ON(PageHighMem(sg_page(sg)));
+#endif
 	return page_address(sg_page(sg)) + sg->offset;
 }
 
-- 
1.7.10.4

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