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Mon, 06 Mar 2023 22:57:13 -0800 (PST) From: Qi Zheng To: akpm@linux-foundation.org, tkhai@ya.ru, hannes@cmpxchg.org, shakeelb@google.com, mhocko@kernel.org, roman.gushchin@linux.dev, muchun.song@linux.dev, david@redhat.com, shy828301@gmail.com, rppt@kernel.org Cc: 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 Subject: [PATCH v4 7/8] mm: vmscan: remove shrinker_rwsem from synchronize_shrinkers() Date: Tue, 7 Mar 2023 14:56:04 +0800 Message-Id: <20230307065605.58209-8-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230307065605.58209-1-zhengqi.arch@bytedance.com> References: <20230307065605.58209-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: E32DA40003 X-Rspam-User: X-Stat-Signature: od79azyw1pzqd9z7ouu93uskkxxb8ou5 X-HE-Tag: 1678172234-874086 X-HE-Meta: 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 PWvzXZvm Yu0ZEFPilOxGCM+cGMnnLcZVh6CEjggI7wXJQFIGNicX8GJ6IeDDOgcjFZl2A8xXSSn6sGflCw86+VraDasYfj/0mNxk6pqHUa5IbE0vyndf486Vp54KczveF/9ld9KdHUPihMiX82aQ4hF9aTYQVq7s56dNDVBu7gauZIBtIPEYro0t8F5Eef2i1pqjcTUV60VYt0akEGeGuNESoT5bMuQ7KumNo++dxWZNSGhLqBMBuYb8bTUpPcSu/U85HezIEtT23ZmoP6vQdiOk4kJX0yCju+rqhVlYh0IT0ddy+HaUuOoc8wcDdPwf+AbUfuM6QKuO7tqOJiOOfOc5YkkKFRNbsx6iv9xCFxyS+FZzdAg4Uw7OEofbGj0CTF494TPd5dVSk6xEiQeNaPjkpHs0aITXm0zaI9qlFd4g0lz1iWOp79cKmvlv8+3AS4r2xutXV23gBM19MAXyxrO5aO9+FRSdV48FmuNOrzy8F X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: 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 --- mm/vmscan.c | 8 ++------ 1 file changed, 2 insertions(+), 6 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 7aaf6f94ac1b..ac7ab4aa344f 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -796,15 +796,11 @@ 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); atomic_inc(&shrinker_srcu_generation); synchronize_srcu(&shrinker_srcu); } -- 2.20.1