Fix compile error on nommu for is_swap_pte

  CC      mm/vmscan.o
In file included from
/home/bunk/linux/kernel-2.6/git/linux-2.6/mm/vmscan.c:44:
/home/bunk/linux/kernel-2.6/git/linux-2.6/include/linux/swapops.h: In function 'is_swap_pte':
/home/bunk/linux/kernel-2.6/git/linux-2.6/include/linux/swapops.h:48: error: implicit declaration of function 'pte_none'
/home/bunk/linux/kernel-2.6/git/linux-2.6/include/linux/swapops.h:48: error: implicit declaration of function 'pte_present'

Does it ever make sense to ask "is this pte a swap entry?" on a machine
with no MMU?  Presumably this also means it has no ptes too, right?  In
which case, it's better to comment the whole function out.  Then when
someone tries to ask the above meaningless question, they get a compile
error rather than a meaningless answer.

Signed-off-by: Matt Mackall <[email protected]>
Cc: Mike Frysinger <[email protected]>
Reported-by: Adrian Bunk <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

1 files changed, 2 insertions, 0 deletions

diff --git a/include/linux/swapops.h b/include/linux/swapops.h
index 7bf2d149d209..6ec39ab27b4b 100644
--- a/include/linux/swapops.h
+++ b/include/linux/swapops.h
@@ -42,11 +42,13 @@ static inline pgoff_t swp_offset(swp_entry_t entry)
 	return entry.val & SWP_OFFSET_MASK(entry);
 }
 
+#ifdef CONFIG_MMU
 /* check whether a pte points to a swap entry */
 static inline int is_swap_pte(pte_t pte)
 {
 	return !pte_none(pte) && !pte_present(pte) && !pte_file(pte);
 }
+#endif
 
 /*
  * Convert the arch-dependent pte representation of a swp_entry_t into an