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Thu, 17 Aug 2023 04:24:48 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([203.208.167.146]) by smtp.gmail.com with ESMTPSA id jd22-20020a170903261600b001bde877a7casm7229309plb.264.2023.08.17.04.24.39 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 17 Aug 2023 04:24:47 -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, joel@joelfernandes.org, christian.koenig@amd.com Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, dri-devel@lists.freedesktop.org, linux-fsdevel@vger.kernel.org, Qi Zheng , Muchun Song Subject: [PATCH v2 3/5] mm: shrinker: remove redundant shrinker_rwsem in debugfs operations Date: Thu, 17 Aug 2023 19:24:00 +0800 Message-Id: <20230817112402.77010-4-zhengqi.arch@bytedance.com> X-Mailer: git-send-email 2.24.3 (Apple Git-128) In-Reply-To: <20230817112402.77010-1-zhengqi.arch@bytedance.com> References: <20230817112402.77010-1-zhengqi.arch@bytedance.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 6320D80031 X-Stat-Signature: k4qo48y456z1wnixqkhurc6ijabzfi35 X-HE-Tag: 1692271489-749588 X-HE-Meta: U2FsdGVkX1+h1jSg61i1sd8IgaRrc1EcZx99xIrtcEj6GHBXuwcHxRM6mC8/ThlhTb+zhRIHxEGwu7o6+/GQJYuFgA2ddXkMdCqsvQPzHWiRtVyoRJVW/A7DaN2n9viw6AJWkh/ectYZ/mGeDBawTGJlF1ZlRSjfrIH7q9wCc9/+b+cLwChGsARO7ZW45H+PbI65M7uve+0nX6ayjCv7uDfrx5tmJXnAmUPC3Wd6m59RQKH08FY8uHnZfRkmYEqFbidH5A+HWOkqABSf44KbDK9oNRhdWh8sKo222+sxG7OpexZP2jVOJS2VqIftsymCs8dhWsCTLQ+ZgfN+Prerk4juoUlnOWEeqqBwpSuGkVVHj828bQlhVRUIPDVeR3uJeZJLXX3UsvXj/1SuhVER3pt7F+EHWfnUI535+Lhp7uXHUpmuIM8TA+tCQXA5er5cfq+KXtuijArqHc+R9xT2sENlkCcxb94O7OivKtSjyCvbaEydeCiVlaKpXHvku+k9OfEjwaXVvYwxxNu2bGiXRGTkg/BmsKrG7MU09i29dM3pwnhrksy1fUAGICZ/nuRtGmpvB6YgGTH8GUfi+rtoBQ5Dfw1206mc+RtL6nDsSONkwtU2dSWElJP03uIBRV0/XeeQZEh8ab0azL7lN1TDlDrnlv/wc6YUIqu+yNO99nDb26n7e6ixhu5RRSsCKOxE1uF7z6MjcGgakNLEbiqzXqvVPWLHM9A5CMr4aTSaHMiFud/IltXP2UUhxbiqwWsBxsqkAg+hZMZMt+yKjapxM+a+DzbZNjAN31lwtcPLbBruYegHIGENwCgLHQT5Ar1i6tPEfvqv9wUJ3kxvlzfJWaJ9xfYQQNO+71KIcrQGs5QrwEHXSD3yqoZ4ayoBfQjgmX6j3Li4rpudPVaj0ASB37f30y1SMX3ws+2XaFVm0atdHcM3lys/Vdy+6Uv/B3dJO24lkZbz19c838pCnkP G8Rkb/jR 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 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: The debugfs_remove_recursive() will wait for debugfs_file_put() to return, so the shrinker will not be freed when doing debugfs operations (such as shrinker_debugfs_count_show() and shrinker_debugfs_scan_write()), so there is no need to hold shrinker_rwsem during debugfs operations. Signed-off-by: Qi Zheng Reviewed-by: Muchun Song --- mm/shrinker_debug.c | 16 +--------------- 1 file changed, 1 insertion(+), 15 deletions(-) diff --git a/mm/shrinker_debug.c b/mm/shrinker_debug.c index ee0cddb4530f..e4ce509f619e 100644 --- a/mm/shrinker_debug.c +++ b/mm/shrinker_debug.c @@ -51,17 +51,12 @@ static int shrinker_debugfs_count_show(struct seq_file *m, void *v) struct mem_cgroup *memcg; unsigned long total; bool memcg_aware; - int ret, nid; + int ret = 0, nid; count_per_node = kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL); if (!count_per_node) return -ENOMEM; - ret = down_read_killable(&shrinker_rwsem); - if (ret) { - kfree(count_per_node); - return ret; - } rcu_read_lock(); memcg_aware = shrinker->flags & SHRINKER_MEMCG_AWARE; @@ -94,7 +89,6 @@ static int shrinker_debugfs_count_show(struct seq_file *m, void *v) } while ((memcg = mem_cgroup_iter(NULL, memcg, NULL)) != NULL); rcu_read_unlock(); - up_read(&shrinker_rwsem); kfree(count_per_node); return ret; @@ -119,7 +113,6 @@ static ssize_t shrinker_debugfs_scan_write(struct file *file, struct mem_cgroup *memcg = NULL; int nid; char kbuf[72]; - ssize_t ret; read_len = size < (sizeof(kbuf) - 1) ? size : (sizeof(kbuf) - 1); if (copy_from_user(kbuf, buf, read_len)) @@ -148,12 +141,6 @@ static ssize_t shrinker_debugfs_scan_write(struct file *file, return -EINVAL; } - ret = down_read_killable(&shrinker_rwsem); - if (ret) { - mem_cgroup_put(memcg); - return ret; - } - sc.nid = nid; sc.memcg = memcg; sc.nr_to_scan = nr_to_scan; @@ -161,7 +148,6 @@ static ssize_t shrinker_debugfs_scan_write(struct file *file, shrinker->scan_objects(shrinker, &sc); - up_read(&shrinker_rwsem); mem_cgroup_put(memcg); return size; -- 2.30.2