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* [PATCH] mm: swap: make free_swap_and_cache()/swapcache_prepare() inline functions
@ 2017-08-23 13:31 Arnd Bergmann
  2017-08-23 18:27 ` Jerome Glisse
  0 siblings, 1 reply; 2+ messages in thread
From: Arnd Bergmann @ 2017-08-23 13:31 UTC (permalink / raw)
  To: Andrew Morton, Stephen Rothwell, Jérôme Glisse
  Cc: Arnd Bergmann, Huang Ying, Johannes Weiner, Tim Chen,
	Minchan Kim, linux-kernel

We get a build warning from a boolean expression that is never used:

mm/madvise.c: In function 'madvise_free_pte_range':
include/linux/swap.h:490:55: error: value computed is not used [-Werror=unused-value]
 #define free_swap_and_cache(e) (is_migration_entry(e) || is_device_private_entry(e))
mm/madvise.c:353:4: note: in expansion of macro 'free_swap_and_cache'

This changes the two macros to a compound expression that gcc does
not warn about. Changing them to inline functions would have been
nicer but is not possible here because that would introduce a recursive
header file dependency.

Fixes: mmotm ("mm/ZONE_DEVICE: new type of ZONE_DEVICE for unaddressable memory")
Signed-off-by: Arnd Bergmann <>
 include/linux/swap.h | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/include/linux/swap.h b/include/linux/swap.h
index 2be396acdf48..8a807292037f 100644
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -487,8 +487,8 @@ static inline void show_swap_cache_info(void)
-#define free_swap_and_cache(e) (is_migration_entry(e) || is_device_private_entry(e))
-#define swapcache_prepare(e) (is_migration_entry(e) || is_device_private_entry(e))
+#define free_swap_and_cache(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
+#define swapcache_prepare(e) ({(is_migration_entry(e) || is_device_private_entry(e));})
 static inline int add_swap_count_continuation(swp_entry_t swp, gfp_t gfp_mask)

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2017-08-23 13:31 [PATCH] mm: swap: make free_swap_and_cache()/swapcache_prepare() inline functions Arnd Bergmann
2017-08-23 18:27 ` Jerome Glisse

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