[PATCH] mm: k{,um}map_atomic() vs in_atomic()

Make kmap_atomic/kunmap_atomic denote a pagefault disabled scope.  All non
trivial implementations already do this anyway.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Nick Piggin <npiggin@suse.de>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 5 insertions, 3 deletions

diff --git a/include/linux/highmem.h b/include/linux/highmem.h
index fd7d12daa94f..3d8768b619e9 100644
--- a/include/linux/highmem.h
+++ b/include/linux/highmem.h
@@ -3,6 +3,7 @@
 
 #include <linux/fs.h>
 #include <linux/mm.h>
+#include <linux/uaccess.h>
 
 #include <asm/cacheflush.h>
 
@@ -41,9 +42,10 @@ static inline void *kmap(struct page *page)
 
 #define kunmap(page) do { (void) (page); } while (0)
 
-#define kmap_atomic(page, idx)          page_address(page)
-#define kunmap_atomic(addr, idx)        do { } while (0)
-#define kmap_atomic_pfn(pfn, idx)       page_address(pfn_to_page(pfn))
+#define kmap_atomic(page, idx) \
+        ({ pagefault_disable(); page_address(page); })
+#define kunmap_atomic(addr, idx)        do { pagefault_enable(); } while (0)
+#define kmap_atomic_pfn(pfn, idx)       kmap_atomic(pfn_to_page(pfn), (idx))
 #define kmap_atomic_to_page(ptr)        virt_to_page(ptr)
 #endif