[PATCH] use might_sleep check if kmap_high is called from atomic context

[zhangchun]

kmap_high is defined as EXPORT_SYMBOL, and cannot be called from atomic
context. Add might_sleep check is necessary.
Signed-off-by: zhangchun <zhang.chuna@xxxxxxx>
---
 mm/highmem.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/mm/highmem.c b/mm/highmem.c
index 07f2c67..5cfb5a9 100644
--- a/mm/highmem.c
+++ b/mm/highmem.c
@@ -319,6 +319,11 @@ void *kmap_high(struct page *page)
 	unsigned long vaddr;
 
 	/*
+	 * Use might_sleep to check if kmap_high is called
+	 * from atomic context.
+	 */
+	might_sleep();
+	/*
 	 * For highmem pages, we can't trust "virtual" until
 	 * after we have the lock.
 	 */
-- 
1.8.3.1