From mboxrd@z Thu Jan 1 00:00:00 1970 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 28AEEC761AF for ; Mon, 3 Apr 2023 14:18:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233006AbjDCOST (ORCPT ); Mon, 3 Apr 2023 10:18:19 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:37886 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233002AbjDCOSS (ORCPT ); Mon, 3 Apr 2023 10:18:18 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [IPv6:2604:1380:4601:e00::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id D3B9F24AE4 for ; Mon, 3 Apr 2023 07:18:16 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id 90D1FB81B92 for ; Mon, 3 Apr 2023 14:18:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E5E1DC433D2; Mon, 3 Apr 2023 14:18:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1680531494; bh=oh7bUmYU8BvxO0wWyyaYbmFA3o0shhnjHA/vDXs+hfY=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=PQQPPBFV19eBabzv9ad1X2WtsjjkllUa7kRGYC2wpXUWs+KApHNdjUVYI2WuJVJji iWdkv5Y9YH6f/g3p/LStxYnEj3b8k7kdMelY8ByjvgbUG4YUKf17JNjjkCrMsdsAO+ 0LlkXGbsUefrsujZaXOUWPcN8UUMSOnbsLxGYg8U= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, syzbot , Tetsuo Handa , Tejun Heo , Cai Xinchen Subject: [PATCH 4.19 84/84] cgroup: Add missing cpus_read_lock() to cgroup_attach_task_all() Date: Mon, 3 Apr 2023 16:09:25 +0200 Message-Id: <20230403140356.288473954@linuxfoundation.org> X-Mailer: git-send-email 2.40.0 In-Reply-To: <20230403140353.406927418@linuxfoundation.org> References: <20230403140353.406927418@linuxfoundation.org> User-Agent: quilt/0.67 MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Tetsuo Handa commit 43626dade36fa74d3329046f4ae2d7fdefe401c6 upstream. syzbot is hitting percpu_rwsem_assert_held(&cpu_hotplug_lock) warning at cpuset_attach() [1], for commit 4f7e7236435ca0ab ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock") missed that cpuset_attach() is also called from cgroup_attach_task_all(). Add cpus_read_lock() like what cgroup_procs_write_start() does. Link: https://syzkaller.appspot.com/bug?extid=29d3a3b4d86c8136ad9e [1] Reported-by: syzbot Signed-off-by: Tetsuo Handa Fixes: 4f7e7236435ca0ab ("cgroup: Fix threadgroup_rwsem <-> cpus_read_lock() deadlock") Signed-off-by: Tejun Heo Signed-off-by: Cai Xinchen Signed-off-by: Greg Kroah-Hartman --- kernel/cgroup/cgroup-v1.c | 3 +++ 1 file changed, 3 insertions(+) --- a/kernel/cgroup/cgroup-v1.c +++ b/kernel/cgroup/cgroup-v1.c @@ -13,6 +13,7 @@ #include #include #include +#include #include @@ -55,6 +56,7 @@ int cgroup_attach_task_all(struct task_s int retval = 0; mutex_lock(&cgroup_mutex); + get_online_cpus(); percpu_down_write(&cgroup_threadgroup_rwsem); for_each_root(root) { struct cgroup *from_cgrp; @@ -71,6 +73,7 @@ int cgroup_attach_task_all(struct task_s break; } percpu_up_write(&cgroup_threadgroup_rwsem); + put_online_cpus(); mutex_unlock(&cgroup_mutex); return retval;