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Mon, 11 Sep 2023 02:51:45 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([203.208.167.146]) by smtp.gmail.com with ESMTPSA id az7-20020a170902a58700b001bdc2fdcf7esm5988188plb.129.2023.09.11.02.51.38 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 11 Sep 2023 02:51:45 -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, steven.price@arm.com, cel@kernel.org, senozhatsky@chromium.org, yujie.liu@intel.com, gregkh@linuxfoundation.org, muchun.song@linux.dev Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, Qi Zheng Subject: [PATCH v6 44/45] mm: shrinker: hold write lock to reparent shrinker nr_deferred Date: Mon, 11 Sep 2023 17:44:43 +0800 Message-Id: <20230911094444.68966-45-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230911094444.68966-1-zhengqi.arch@bytedance.com> References: <20230911094444.68966-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 X-Rspamd-Queue-Id: D1CD11C000F X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: u9zqare56d7wnqnud6crxxpmbw41ues5 X-HE-Tag: 1694425906-267806 X-HE-Meta: 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 VPAn5qC+ XwyEJDaZO6TqgYzOvs/eksvUzIiWqELljKlT6KeCYjzqPRLVIU+iaGQ2i9jCR/du/M1DYGtwjW4P0y1i9g+x3++hFcc2cCF/hgiGqd00mD+wIrY5E3bYMXmoRfxjMQBlLl0ou6DnxbWfede9dA3lz2JMv5I/Ggk44exiTbiIouNqF4jbjKJlBlJyvMM8BTGsXxmFAfXfw5yfcuTQLQ+waTB5wUSFO/Rbs9CkYrfASRh6WiuaeHe8e/vmaCAlj+gkYpB7WkipXdfSnxUlogyin+1oidgdevWa1KtN9AoGsuVLirzFheiWkKU5Kw47K4kYwG13Lww3ffku3xt41B6zxQmQhdQLgpL5ms5eL7gW3FwmV6CLG3OCkBugbMC67cqFBvSkcH0bh5KvNgh8aR53T8qqQjf611ztrdyWTXL4vjVTu5+hHqqlcBiDjDzgmXc1xH3dGeSs7wlL0/JEULmcHuHGjbg== 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 Reviewed-by: Muchun Song --- mm/shrinker.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/shrinker.c b/mm/shrinker.c index ad64cac5248c..471c07d75c4a 100644 --- a/mm/shrinker.c +++ b/mm/shrinker.c @@ -292,7 +292,7 @@ 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); @@ -305,7 +305,7 @@ void reparent_shrinker_deferred(struct mem_cgroup *memcg) } } } - up_read(&shrinker_rwsem); + up_write(&shrinker_rwsem); } #else static int shrinker_memcg_alloc(struct shrinker *shrinker)