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Mon, 06 Mar 2023 22:57:06 -0800 (PST) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.245]) by smtp.gmail.com with ESMTPSA id e5-20020a62ee05000000b00608dae58695sm7230854pfi.209.2023.03.06.22.56.59 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 06 Mar 2023 22:57:06 -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 6/8] mm: vmscan: hold write lock to reparent shrinker nr_deferred Date: Tue, 7 Mar 2023 14:56:03 +0800 Message-Id: <20230307065605.58209-7-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 X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: ks7hh6dz8ftmza4465apo9ng43rwiqg8 X-Rspamd-Queue-Id: 9978040003 X-HE-Tag: 1678172227-100868 X-HE-Meta: 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 imhBuz7x 49jQ1EAEmZC/ACTKdVHKjiDpUZPVHknDi0VQiW/1Cs2SxsGgpIUWJQJcWWwov5qjcOfG4ri6ZYilrFF6Gyf1MqYrd05HNsiYhL3SDMcS6SfYCH0v0wEJxzVtfVUctb/7EVQJ7u3S6Ig8ssh0+Fdot5cLNLxXYuKwocuCwi+qIzDUZZTbS+zqY1wV539SnMTX3Cr9P1kP6wyiuOJdfhJoJtraWz6oVoD2x+K3n+PqcJFHHrujsd2VDjYN3k36tnrpvyjNVzJlMzdEvFk1T0QX/b8LE3njauQs92K+4mv8FC/JpszKG48UAwSbs6X42YFw1S9c3ahfPsTeABzzBleNM95NTeiTwxgmfLCwD0gYk03SguHPkb/Tft6P4KVZ9c5XknAFMXqHmcLP3Xk+OHn5T14nDayCdzACbPKhy2KQ/6q7FFh74EETmNUpdHj0YXkMKc824IyueylspPicpeSCrWLxce5PJT5GpnOsB 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: For now, reparent_shrinker_deferred() is the only holder of read lock of shrinker_rwsem. And it already holds the global cgroup_mutex, so it will not be called in parallel. Therefore, in order to convert shrinker_rwsem to shrinker_mutex later, here we change to hold the write lock of shrinker_rwsem to reparent. Signed-off-by: Qi Zheng Acked-by: Vlastimil Babka --- mm/vmscan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 9a5a3da5c8b5..7aaf6f94ac1b 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -451,7 +451,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) parent = root_mem_cgroup; /* Prevent from concurrent shrinker_info expand */ - down_read(&shrinker_rwsem); + down_write(&shrinker_rwsem); for_each_node(nid) { child_info = shrinker_info_protected(memcg, nid); parent_info = shrinker_info_protected(parent, nid); @@ -460,7 +460,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) atomic_long_add(nr, &parent_info->nr_deferred[i]); } } - up_read(&shrinker_rwsem); + up_write(&shrinker_rwsem); } static bool cgroup_reclaim(struct scan_control *sc)