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Thu, 22 Jun 2023 01:57:40 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([139.177.225.254]) by smtp.gmail.com with ESMTPSA id h2-20020a170902f7c200b001b549fce345sm4806971plw.230.2023.06.22.01.57.32 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 22 Jun 2023 01:57:39 -0700 (PDT) From: Qi Zheng To: akpm@linux-foundation.org, david@fromorbit.com, tkhai@ya.ru, vbabka@suse.cz, roman.gushchin@linux.dev, djwong@kernel.org, brauner@kernel.org, paulmck@kernel.org, tytso@mit.edu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, intel-gfx@lists.freedesktop.org, dri-devel@lists.freedesktop.org, linux-arm-msm@vger.kernel.org, dm-devel@redhat.com, linux-raid@vger.kernel.org, linux-bcache@vger.kernel.org, virtualization@lists.linux-foundation.org, linux-fsdevel@vger.kernel.org, linux-ext4@vger.kernel.org, linux-nfs@vger.kernel.org, linux-xfs@vger.kernel.org, linux-btrfs@vger.kernel.org, Qi Zheng Subject: [PATCH 27/29] mm: vmscan: hold write lock to reparent shrinker nr_deferred Date: Thu, 22 Jun 2023 16:53:33 +0800 Message-Id: <20230622085335.77010-28-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230622085335.77010-1-zhengqi.arch@bytedance.com> References: <20230622085335.77010-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: 3C1532000C X-Rspam-User: X-Rspamd-Server: rspam05 X-Stat-Signature: b5hwup9nrwn6hjubhrpp7um4pi5tu7g3 X-HE-Tag: 1687424260-38298 X-HE-Meta: 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 7fd8uFG/ wAl1JZi8NPgDQuuIlweRgEt+6K1toM7ntKc92pmGHOvxycUUT8c21BtTuKJzw7HJXltvNT9cUuJK7Gc7O7mIVbPNgmj7AxrPXPV/62qx74FvIfEELs/Q/Nbx4Es0QVDLFUPK45cw7AetJhKVbc1Z+ngDAjyoNiREXuB7LbVWCbx53WJVmKU08guovmXps66r1H9Q3vsRt06HWgX1fmecZCUbwJ2JlMFgs9/SdIzHN12/EYjbgwyrE70HWAKkSuAfWaKkiet+qKWa7F432yATKtrAwaYIJCL9wB2GLL7wj0X3xsH67Ka1ks4wx6FK36w5PMe8has5zmWdJtTRmZBwLgcvuwdSAlRBmoqE1st5U3HDDH0IMxuWW9lI7TfRZ6JPoimBLu2nSl75b9YmYvA3oFnfJsh2aNscJUlh8iTVz+xMBe7B/rbI2yGeQiIp8Vru54Z8aYp9dtFHxXUkGtFVr1Z7YCA== 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 --- mm/vmscan.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/vmscan.c b/mm/vmscan.c index 357a1f2ad690..0711b63e68d9 100644 --- a/mm/vmscan.c +++ b/mm/vmscan.c @@ -433,7 +433,7 @@ 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); @@ -442,7 +442,7 @@ 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)