From:   Qi Zheng <zhengqi.arch@bytedance.com>
To:     akpm@linux-foundation.org, hannes@cmpxchg.org, shakeelb@google.com,
        mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev,
        david@redhat.com, shy828301@gmail.com
Cc:     tkhai@ya.ru, sultan@kerneltoast.com, dave@stgolabs.net,
        penguin-kernel@I-love.SAKURA.ne.jp, paulmck@kernel.org,
        linux-mm@kvack.org, linux-kernel@vger.kernel.org,
        Qi Zheng <zhengqi.arch@bytedance.com>
Subject: [PATCH 4/5] mm: vmscan: remove shrinker_rwsem from synchronize_shrinkers()
Date:   Mon, 20 Feb 2023 17:16:36 +0800
Message-Id: <20230220091637.64865-5-zhengqi.arch@bytedance.com>
In-Reply-To: <20230220091637.64865-1-zhengqi.arch@bytedance.com>
References: <20230220091637.64865-1-zhengqi.arch@bytedance.com>
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Now there are no readers of shrinker_rwsem, so
synchronize_shrinkers() does not need to hold the
writer of shrinker_rwsem to wait for all running
shinkers to complete, synchronize_srcu() is enough.

Signed-off-by: Qi Zheng <zhengqi.arch@bytedance.com>
---
 mm/vmscan.c | 8 ++------
 1 file changed, 2 insertions(+), 6 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index dc47396ecd0e..b8da56beba96 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -787,15 +787,11 @@ EXPORT_SYMBOL(unregister_shrinker);
 /**
  * synchronize_shrinkers - Wait for all running shrinkers to complete.
  *
- * This is equivalent to calling unregister_shrink() and register_shrinker(),
- * but atomically and with less overhead. This is useful to guarantee that all
- * shrinker invocations have seen an update, before freeing memory, similar to
- * rcu.
+ * This is useful to guarantee that all shrinker invocations have seen an
+ * update, before freeing memory.
  */
 void synchronize_shrinkers(void)
 {
-	down_write(&shrinker_rwsem);
-	up_write(&shrinker_rwsem);
 	synchronize_srcu(&shrinker_srcu);
 }
 EXPORT_SYMBOL(synchronize_shrinkers);
-- 
2.20.1