linux-kernel - [PATCH v2 1/3] mm: vmscan: move shrinker_debugfs_remove() before synchronize

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Message-Id: <168599178203.70911.18350742045278218790.stgit@pro.pro>
Date:   Mon,  5 Jun 2023 22:03:02 +0300
From:   Kirill Tkhai <tkhai@...ru>
To:     akpm@...ux-foundation.org, tkhai@...ru, roman.gushchin@...ux.dev,
        vbabka@...e.cz, viro@...iv.linux.org.uk, brauner@...nel.org,
        djwong@...nel.org, hughd@...gle.com, paulmck@...nel.org,
        muchun.song@...ux.dev, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, linux-xfs@...r.kernel.org,
        linux-kernel@...r.kernel.org, zhengqi.arch@...edance.com,
        david@...morbit.com
Subject: [PATCH v2 1/3] mm: vmscan: move shrinker_debugfs_remove() before synchronize_srcu()

From: Qi Zheng <zhengqi.arch@...edance.com>

The debugfs_remove_recursive() will wait for debugfs_file_put()
to return, so there is no need to put it after synchronize_srcu()
to wait for the rcu read-side critical section to exit.

Just move it before synchronize_srcu(), which is also convenient
to put the heavy synchronize_srcu() in the delayed work later.

Signed-off-by: Qi Zheng <zhengqi.arch@...edance.com>
---
 mm/vmscan.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index eeca83e28c9b..a773e97e152e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -818,11 +818,11 @@ void unregister_shrinker(struct shrinker *shrinker)
 	debugfs_entry = shrinker_debugfs_detach(shrinker, &debugfs_id);
 	mutex_unlock(&shrinker_mutex);
 
+	shrinker_debugfs_remove(debugfs_entry, debugfs_id);
+
 	atomic_inc(&shrinker_srcu_generation);
 	synchronize_srcu(&shrinker_srcu);
 
-	shrinker_debugfs_remove(debugfs_entry, debugfs_id);
-
 	kfree(shrinker->nr_deferred);
 	shrinker->nr_deferred = NULL;
 }