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Mon, 07 Aug 2023 04:20:00 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([203.208.167.146]) by smtp.gmail.com with ESMTPSA id y13-20020a17090aca8d00b0025be7b69d73sm5861191pjt.12.2023.08.07.04.19.47 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Aug 2023 04:19:59 -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, simon.horman@corigine.com, dlemoal@kernel.org Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, x86@kernel.org, kvm@vger.kernel.org, xen-devel@lists.xenproject.org, linux-erofs@lists.ozlabs.org, linux-f2fs-devel@lists.sourceforge.net, cluster-devel@redhat.com, linux-nfs@vger.kernel.org, linux-mtd@lists.infradead.org, rcu@vger.kernel.org, netdev@vger.kernel.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-xfs@vger.kernel.org, linux-btrfs@vger.kernel.org, Qi Zheng Subject: [PATCH v4 47/48] mm: shrinker: hold write lock to reparent shrinker nr_deferred Date: Mon, 7 Aug 2023 19:09:35 +0800 Message-Id: <20230807110936.21819-48-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230807110936.21819-1-zhengqi.arch@bytedance.com> References: <20230807110936.21819-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 X-Rspam-User: X-Stat-Signature: 3komjzdnq5feuoca1x5trip9oxj643yx X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 5F7F9100011 X-HE-Tag: 1691407201-908243 X-HE-Meta: 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 7gw9MBlY IlQHAhMGxjoX9XVORRlHwPhP+c3o+SLiez2uuc60PMsFU+aGyUjB4MJToPzWBDS1wP0KjrPXse1wSBd0V3zD+Y8lhlgEihASH+jr9fKKGYzdQCzKmwbvttAVaxrUxVsrKdgSzVU0zDongZV+HSe0Fc2o+/5MTaB2K2L65I6ThY1vB/VyCX7LBOCTIrEBDLk8XFaAk3E505ROs35xIVLPzZ11Zu+mlcU2N5Ibe5L0Kg3GT9+Mq0hzIlXHEJJriNmG60+eF6goaWYkw+g8rAro5taI4kXAn/KiUCyXAHkjTvVNJsKlklW5KW29vKr8LSeK9aqQoHfPcVSWlJniS3zEwBYkHueTKlUWAYUd8Fe5VucdQaixy2INu9Ra8wpO7uXpkhH4govY6DLuBK8Cb7Rrdz6fbKr14Ty7gdXp618AJCJAyUMJI+T2rqcvnGmR6JbSxFh3zZnICaCHY0TBnjMfcmvzIeQ== 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/shrinker.c | 4 ++-- 1 file changed, 2 insertions(+), 2 deletions(-) diff --git a/mm/shrinker.c b/mm/shrinker.c index fee6f62904fb..a12dede5d21f 100644 --- a/mm/shrinker.c +++ b/mm/shrinker.c @@ -299,7 +299,7 @@ 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); @@ -312,7 +312,7 @@ 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)