From nobody Thu Dec 18 13:14:29 2025 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 80112C2FC24 for ; Thu, 17 Aug 2023 11:25:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1350330AbjHQLZe (ORCPT ); Thu, 17 Aug 2023 07:25:34 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58728 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1350263AbjHQLZM (ORCPT ); Thu, 17 Aug 2023 07:25:12 -0400 Received: from mail-pl1-x632.google.com (mail-pl1-x632.google.com [IPv6:2607:f8b0:4864:20::632]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D30AF30C7 for ; Thu, 17 Aug 2023 04:24:48 -0700 (PDT) Received: by mail-pl1-x632.google.com with SMTP id d9443c01a7336-1b89b0c73d7so10960625ad.1 for ; Thu, 17 Aug 2023 04:24:48 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1692271488; x=1692876288; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:from:to:cc:subject:date :message-id:reply-to; bh=q7bwmZAFhPRfqsSPFwB3IV8LJcvLn4gI9V7ELWjZ+Dw=; b=E667FU1q5yUbFYqx9BwHEJkdNAgKfidWcc5ZgjhQQ/mESjGah7FzWCA300/igNm9V3 iELPRn+pzOK/NtZ+GP4yOP+jMtWST+yUR68q9CpS5n9zjZZGhZfyu7/xo/HJFBwFsgdS Fn2bIiASzCPYYzQ8hJlk3AtvoZUod5eY7ys6Lly6upo9qdeEMtkENep5f6dARROB8Qtv 3eSp2HAIS/Zfh5EDeYYzF8GMIWSCZ6wmum3AMCbPgzO+3hsAVAsjBi9fOix0lM4b6AEH 46KmG8k7sUEmxdKHvkXOGiZfxhdT/VBl9qeYF1l77ZmXhkuGTPaCq3PQ0MHkM/+lNa1w TnLA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1692271488; x=1692876288; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:date:subject:cc:to:from:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=q7bwmZAFhPRfqsSPFwB3IV8LJcvLn4gI9V7ELWjZ+Dw=; b=LeYt6riL28LR9LBrUo6rK9KYtNwggZCNR9wlg1BH+IHetT/mu2+JgFKAbPVuqgDqsJ Ftk5l/GJIYQBMPGdHXXiLcwbGXUTe4cDKFdcTTXUhR1P982hXBb3Ztsk21okso8qdLvs NTTzOx9CpgDjplHeZnlXw6KB5bfYdqcF3V7UvCVwaub1q/F9lLxdCVm4HvjIw5+Bx0rW /1yjM7B+du0x5wptybXL54U68GxCjNXHEo1Vg4YCCFEyk+AsR0Pg2jspyFcJ4fowNOOY VYVVYxl1MZhKHKkbrWvd3pBSH7RgojG4jp93+YZroJczGXahro7qQScb9uNzAwTloOLB mk6Q== X-Gm-Message-State: AOJu0Ywh6lb2C9Ygc6l8Fq8ptZPflb5qoO7lMLiqXpiAEN1O4WzZylZx 8g3JCzuP2thhbxdL4DqABYV1qWASKR1rSU2DFbU= X-Google-Smtp-Source: AGHT+IFkvJTgDp0SXlu0lQRx4ok9QX20WzaEZhlm1VB3qb5n/lSGDntzihW5jKwOury0iV0Wn4jxUQ== X-Received: by 2002:a17:903:1208:b0:1b8:aded:524c with SMTP id l8-20020a170903120800b001b8aded524cmr5464540plh.1.1692271488357; 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: quoted-printable Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Type: text/plain; charset="utf-8" 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 =3D 0, nid; =20 count_per_node =3D kcalloc(nr_node_ids, sizeof(unsigned long), GFP_KERNEL= ); if (!count_per_node) return -ENOMEM; =20 - ret =3D down_read_killable(&shrinker_rwsem); - if (ret) { - kfree(count_per_node); - return ret; - } rcu_read_lock(); =20 memcg_aware =3D shrinker->flags & SHRINKER_MEMCG_AWARE; @@ -94,7 +89,6 @@ static int shrinker_debugfs_count_show(struct seq_file *m= , void *v) } while ((memcg =3D mem_cgroup_iter(NULL, memcg, NULL)) !=3D NULL); =20 rcu_read_unlock(); - up_read(&shrinker_rwsem); =20 kfree(count_per_node); return ret; @@ -119,7 +113,6 @@ static ssize_t shrinker_debugfs_scan_write(struct file = *file, struct mem_cgroup *memcg =3D NULL; int nid; char kbuf[72]; - ssize_t ret; =20 read_len =3D 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; } =20 - ret =3D down_read_killable(&shrinker_rwsem); - if (ret) { - mem_cgroup_put(memcg); - return ret; - } - sc.nid =3D nid; sc.memcg =3D memcg; sc.nr_to_scan =3D nr_to_scan; @@ -161,7 +148,6 @@ static ssize_t shrinker_debugfs_scan_write(struct file = *file, =20 shrinker->scan_objects(shrinker, &sc); =20 - up_read(&shrinker_rwsem); mem_cgroup_put(memcg); =20 return size; --=20 2.30.2