linux-kernel - [PATCH v2 8/8] rcu/kfree: Fix kfree_rcu_shrink

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Message-Id: <20220622225102.2112026-10-joel@joelfernandes.org>
Date:   Wed, 22 Jun 2022 22:51:02 +0000
From:   "Joel Fernandes (Google)" <joel@...lfernandes.org>
To:     rcu@...r.kernel.org
Cc:     linux-kernel@...r.kernel.org, rushikesh.s.kadam@...el.com,
        urezki@...il.com, neeraj.iitr10@...il.com, frederic@...nel.org,
        paulmck@...nel.org, rostedt@...dmis.org, vineeth@...byteword.org,
        "Joel Fernandes (Google)" <joel@...lfernandes.org>
Subject: [PATCH v2 8/8] rcu/kfree: Fix kfree_rcu_shrink_count() return value

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@...lfernandes.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 711679d10cbb..935788e8d2d7 100644
--- a/kernel/rcu/tree.c
+++ b/kernel/rcu/tree.c
@@ -3722,7 +3722,7 @@ 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
-- 
2.37.0.rc0.104.g0611611a94-goog