From patchwork Mon Aug 7 11:08:51 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Qi Zheng X-Patchwork-Id: 13343417 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 9853AC04FE2 for ; Mon, 7 Aug 2023 11:11:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231895AbjHGLLM (ORCPT ); Mon, 7 Aug 2023 07:11:12 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:48372 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231960AbjHGLLC (ORCPT ); Mon, 7 Aug 2023 07:11:02 -0400 Received: from mail-pj1-x1032.google.com (mail-pj1-x1032.google.com [IPv6:2607:f8b0:4864:20::1032]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 8269B1BE4 for ; Mon, 7 Aug 2023 04:10:36 -0700 (PDT) Received: by mail-pj1-x1032.google.com with SMTP id 98e67ed59e1d1-265c94064b8so592328a91.0 for ; Mon, 07 Aug 2023 04:10:36 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=bytedance.com; s=google; t=1691406635; x=1692011435; 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=v13l7IPlOPgFsnMxGKXfyNRR5BVZeBzBNEaAsOIHoYU=; b=kCYTaRcfjrYSEt8G3Tw1f1acTO5J6yxn7oF0SsGLa85MduwVEgH5omvSEO969tp3LA wpvSUu2A7//qJL2ilMqNB9PtHKQAFVNRC9oXX6TEGsUMhNv4mOxpl2C1YAZnVZpulCYe yLDYKwIJ4bAvkX2QuqtJJDYUJRh6vr19t7PfH+lhQ++ji8JDwdveN3FzqnpipfKLqAIG dvafeOsYb5J4XciY9gtlA1gSl238AIRfFhWaOJMr5WdeT5BLHH+Cl6s3+MJ/6Htxm+Cq sbYQtf3+i0mELZ2fQ4kGZP1NFS47ge8l8Znqj7GoIxgmAjgbPULzYpOui4TUq64XmvYi qgMw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1691406635; x=1692011435; 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=v13l7IPlOPgFsnMxGKXfyNRR5BVZeBzBNEaAsOIHoYU=; b=d7A5Ct6l3RcTBX1W9QwQP14ccp7kiGNwUz2Y4jdinQb+xuPrTcgHvNLZZt7SwxefdA q0aZuP9c2VomP2Nw9j5RSw3csSEkXOJD2rdm0OuQr0Jq+4Vg02ic+uYloMKTiUQLInnJ FnES7Cp+mf2G5tdI/lQuHvNgz0YpIChVXFTUscirxm2UMrsQv0ZFwvycCjXdOou2X3U+ POz7abdQeS6F04BIlFox1LZJS6C7k2A0ZTZtqfjAUoBZVvAeMd/LBW5aVpM8rMUlb8wX RvkP1RW9RMzA4nSk2yrdZ0pCVI2o6H759mw6zk6SGfsYldtmZ0mrIw+WhpH9g9qGewXz xsBA== X-Gm-Message-State: AOJu0Yxvj9FE/8s7dXM426fFf2nKnRgequH+FhWZhChpAcggmmc6sb2D dRoepAcq2WfWkrlXvZyVzwacmg== X-Google-Smtp-Source: AGHT+IFtRmyHpiiF2qszY30g7vYVkD2mnACy5d4vfrtyjmwLjyswWFf77Xamslud93nGDOipc3oAlA== X-Received: by 2002:a17:90a:69c4:b0:269:34a6:d4ca with SMTP id s62-20020a17090a69c400b0026934a6d4camr6363728pjj.0.1691406635181; Mon, 07 Aug 2023 04:10:35 -0700 (PDT) Received: from C02DW0BEMD6R.bytedance.net ([203.208.167.146]) by smtp.gmail.com with ESMTPSA id y13-20020a17090aca8d00b0025be7b69d73sm5861191pjt.12.2023.08.07.04.10.22 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 07 Aug 2023 04:10:34 -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 , Muchun Song Subject: [PATCH v4 03/48] mm: shrinker: remove redundant shrinker_rwsem in debugfs operations Date: Mon, 7 Aug 2023 19:08:51 +0800 Message-Id: <20230807110936.21819-4-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 Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org 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 3ab53fad8876..61702bdc1af4 100644 --- a/mm/shrinker_debug.c +++ b/mm/shrinker_debug.c @@ -49,17 +49,12 @@ 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; @@ -92,7 +87,6 @@ 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; @@ -117,7 +111,6 @@ 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)) @@ -146,12 +139,6 @@ 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; @@ -159,7 +146,6 @@ 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;