[RFC v1 13/14] rcu/kfree: Fix kfree_rcu_shrink_count() return value

From: "Joel Fernandes (Google)" <joel@joelfernandes.org>
To: rcu@vger.kernel.org
Cc: rushikesh.s.kadam@intel.com, urezki@gmail.com,
	neeraj.iitr10@gmail.com, frederic@kernel.org, paulmck@kernel.org,
	rostedt@goodmis.org,
	"Joel Fernandes (Google)" <joel@joelfernandes.org>
Subject: [RFC v1 13/14] rcu/kfree: Fix kfree_rcu_shrink_count() return value
Date: Thu, 12 May 2022 03:04:41 +0000	[thread overview]
Message-ID: <20220512030442.2530552-14-joel@joelfernandes.org> (raw)
In-Reply-To: <20220512030442.2530552-1-joel@joelfernandes.org>

As per the comments in include/linux/shrinker.h, .count_objects callback
should return the number of freeable items, but if there are no objects
to free, SHRINK_EMPTY should be returned. The only time 0 is returned
should be when we are unable to determine the number of objects, or the
cache should be skipped for another reason.

Signed-off-by: Joel Fernandes (Google) <joel@joelfernandes.org>
---
 kernel/rcu/tree.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c
index 3828ac3bf1c4..f191542cdf5e 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3637,7 +3637,7 @@ kfree_rcu_shrink_count(struct shrinker *shrink, struct shrink_control *sc)
 		atomic_set(&krcp->backoff_page_cache_fill, 1);
 	}
 
-	return count;
+	return count == 0 ? SHRINK_EMPTY : count;
 }
 
 static unsigned long
-- 
2.36.0.550.gb090851708-goog

