[PATCH v2 2/2] mm,vmscan: Mark register_shrinker() as __must_check

[Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>]

Commit 1d3d4437eae1bb29 ("vmscan: per-node deferred work") changed
register_shrinker() to fail when memory allocation failed.
Since that commit did not take appropriate precautions before allowing
register_shrinker() to fail, there are many register_shrinker() users
who continue running when register_shrinker() failed.
Since continuing when register_shrinker() failed can cause memory
pressure related issues (e.g. needless OOM killer invocations),
this patch marks register_shrinker() as __must_check in order to
encourage all register_shrinker() users to add error recovery path.

Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
Cc: Glauber Costa <glauber@scylladb.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>
---
 include/linux/shrinker.h | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/include/linux/shrinker.h b/include/linux/shrinker.h
index 388ff29..a389491 100644
--- a/include/linux/shrinker.h
+++ b/include/linux/shrinker.h
@@ -75,6 +75,6 @@ struct shrinker {
 #define SHRINKER_NUMA_AWARE	(1 << 0)
 #define SHRINKER_MEMCG_AWARE	(1 << 1)
 
-extern int register_shrinker(struct shrinker *);
+extern __must_check int register_shrinker(struct shrinker *);
 extern void unregister_shrinker(struct shrinker *);
 #endif
-- 
1.8.3.1

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