[patch 44/49] Fix __pfn_to_page(pfn) for CONFIG_DISCONTIGMEM=y

Greg KH
2008-11-12T00:42:54Z

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2.6.27-stable review patch. If anyone has any objections, please let us know.

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From: Rafael J. Wysocki <rjw@sisk.pl>

commit c5d712433ff57a66d8fb79a57a4fc7a7c3467b97 upstream

Fix the __pfn_to_page(pfn) macro so that it doesn't evaluate its
argument twice in the CONFIG_DISCONTIGMEM=y case, because 'pfn' may
be a result of a funtion call having side effects.

For example, the hibernation code applies pfn_to_page(pfn) to the
result of a function returning the pfn corresponding to the next set
bit in a bitmap and the current bit position is modified on each
call. This leads to "interesting" failures for CONFIG_DISCONTIGMEM=y
due to the current behavior of __pfn_to_page(pfn).

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@suse.cz>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

---
include/asm-generic/memory_model.h | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/include/asm-generic/memory_model.h
+++ b/include/asm-generic/memory_model.h
@@ -34,7 +34,7 @@

#define __pfn_to_page(pfn) \
({ unsigned long __pfn = (pfn); \
- unsigned long __nid = arch_pfn_to_nid(pfn); \
+ unsigned long __nid = arch_pfn_to_nid(__pfn); \
NODE_DATA(__nid)->node_mem_map + arch_local_page_offset(__pfn, __nid);\
})

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