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 E858DC7618D for ; Thu, 6 Apr 2023 12:18:53 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237252AbjDFMSw (ORCPT ); Thu, 6 Apr 2023 08:18:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57156 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229771AbjDFMSv (ORCPT ); Thu, 6 Apr 2023 08:18:51 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 51EAF61B1 for ; Thu, 6 Apr 2023 05:18:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1680783483; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=x1I6xnPQCFgaa8GiBqNBRb9FGr8oj3ORM8xu7RlaLgc=; b=dLT6usFa0POlshGw7eRWDhfMswRRSBzEQh1tv56dezP9wgiGxUEMq0aOVdJ0fCzlGGKjgY t7rby5uy5mXEiz7P/2EwbIAMpia1azcH3yBWlJugjeinSp7XCcbcDzYZK9nwPuHvRMDqZ9 yiCP64nEVGbwg4+cwxD1fs4xnazT7wo= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-247-XgrpVXFHNnOhM06Sbit5sw-1; Thu, 06 Apr 2023 08:18:00 -0400 X-MC-Unique: XgrpVXFHNnOhM06Sbit5sw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.rdu2.redhat.com [10.11.54.6]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id D3F8B8996E2; Thu, 6 Apr 2023 12:17:59 +0000 (UTC) Received: from [10.22.9.26] (unknown [10.22.9.26]) by smtp.corp.redhat.com (Postfix) with ESMTP id 22F002166B26; Thu, 6 Apr 2023 12:17:59 +0000 (UTC) Message-ID: <1f5e2876-8230-32b5-7bd8-99415d079896@redhat.com> Date: Thu, 6 Apr 2023 08:17:58 -0400 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.7.1 Subject: Re: [PATCH 1/3] cgroup/cpuset: Make cpuset_fork() handle CLONE_INTO_CGROUP properly Content-Language: en-US To: kernel test robot Cc: oe-lkp@lists.linux.dev, lkp@intel.com, cgroups@vger.kernel.org, Tejun Heo , Zefan Li , Johannes Weiner , Christian Brauner , linux-kernel@vger.kernel.org, Juri Lelli , Dietmar Eggemann , gscrivan@redhat.com References: <202304061003.e5e0dc9c-yujie.liu@intel.com> From: Waiman Long In-Reply-To: <202304061003.e5e0dc9c-yujie.liu@intel.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Scanned-By: MIMEDefang 3.1 on 10.11.54.6 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/5/23 22:51, kernel test robot wrote: > Hello, > > kernel test robot noticed "WARNING:suspicious_RCU_usage" on: > > commit: a53ab2ba098e6839db602212831c8b62a38c2956 ("[PATCH 1/3] cgroup/cpuset: Make cpuset_fork() handle CLONE_INTO_CGROUP properly") > url: https://github.com/intel-lab-lkp/linux/commits/Waiman-Long/cgroup-cpuset-Make-cpuset_fork-handle-CLONE_INTO_CGROUP-properly/20230331-225527 > base: https://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git 62bad54b26db8bc98e28749cd76b2d890edb4258 > patch link: https://lore.kernel.org/all/20230331145045.2251683-2-longman@redhat.com/ > patch subject: [PATCH 1/3] cgroup/cpuset: Make cpuset_fork() handle CLONE_INTO_CGROUP properly > > in testcase: boot > > compiler: gcc-11 > test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G > > (please refer to attached dmesg/kmsg for entire log/backtrace) > > > If you fix the issue, kindly add following tag > | Reported-by: kernel test robot > | Link: https://lore.kernel.org/oe-lkp/202304061003.e5e0dc9c-yujie.liu@intel.com > > > [ 2.798551][ T2] WARNING: suspicious RCU usage > [ 2.799473][ T2] 6.3.0-rc4-00162-ga53ab2ba098e #1 Not tainted > [ 2.799901][ T2] ----------------------------- > [ 2.800551][ T2] include/linux/cgroup.h:437 suspicious rcu_dereference_check() usage! > [ 2.802044][ T2] > [ 2.802044][ T2] other info that might help us debug this: > [ 2.802044][ T2] > [ 2.803158][ T2] > [ 2.803158][ T2] rcu_scheduler_active = 1, debug_locks = 1 > [ 2.804024][ T2] 1 lock held by kthreadd/2: > [ 2.804851][ T2] #0: ffffffff84c38230 (cgroup_threadgroup_rwsem){.+.+}-{0:0}, at: cgroup_can_fork (kernel/cgroup/cgroup.c:6515) > [ 2.806112][ T2] > [ 2.806112][ T2] stack backtrace: > [ 2.806958][ T2] CPU: 0 PID: 2 Comm: kthreadd Not tainted 6.3.0-rc4-00162-ga53ab2ba098e #1 > [ 2.807537][ T2] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-debian-1.16.0-5 04/01/2014 > [ 2.807537][ T2] Call Trace: > [ 2.807537][ T2] > [ 2.807537][ T2] dump_stack_lvl (lib/dump_stack.c:107) > [ 2.807537][ T2] lockdep_rcu_suspicious (include/linux/context_tracking.h:153 kernel/locking/lockdep.c:6600) > [ 2.807537][ T2] cpuset_fork (include/linux/cgroup.h:437 kernel/cgroup/cpuset.c:240 kernel/cgroup/cpuset.c:3262) > [ 2.807537][ T2] cgroup_post_fork (kernel/cgroup/cgroup.c:6635 (discriminator 6)) > [ 2.807537][ T2] ? cgroup_cancel_fork (kernel/cgroup/cgroup.c:6573) > [ 2.807537][ T2] ? mark_held_locks (kernel/locking/lockdep.c:4237) > [ 2.807537][ T2] ? lockdep_hardirqs_on_prepare (kernel/locking/lockdep.c:4529) > [ 2.807537][ T2] copy_process (kernel/fork.c:2499) > [ 2.807537][ T2] ? __cleanup_sighand (kernel/fork.c:2013) > [ 2.807537][ T2] ? __lock_acquire (kernel/locking/lockdep.c:186 kernel/locking/lockdep.c:3836 kernel/locking/lockdep.c:5056) > [ 2.807537][ T2] kernel_clone (include/linux/random.h:26 kernel/fork.c:2680) > [ 2.807537][ T2] ? create_io_thread (kernel/fork.c:2639) > [ 2.807537][ T2] ? mark_usage (kernel/locking/lockdep.c:4914) > [ 2.807537][ T2] ? finish_task_switch+0x21c/0x910 > [ 2.807537][ T2] ? __switch_to (arch/x86/include/asm/bitops.h:55 include/asm-generic/bitops/instrumented-atomic.h:29 include/linux/thread_info.h:89 arch/x86/include/asm/fpu/sched.h:65 arch/x86/kernel/process_64.c:623) > [ 2.807537][ T2] kernel_thread (kernel/fork.c:2729) > [ 2.807537][ T2] ? __ia32_sys_clone3 (kernel/fork.c:2729) > [ 2.807537][ T2] ? lock_downgrade (kernel/locking/lockdep.c:5321) > [ 2.807537][ T2] ? kthread_complete_and_exit (kernel/kthread.c:331) > [ 2.807537][ T2] ? do_raw_spin_unlock (arch/x86/include/asm/atomic.h:29 include/linux/atomic/atomic-instrumented.h:28 include/asm-generic/qspinlock.h:57 kernel/locking/spinlock_debug.c:100 kernel/locking/spinlock_debug.c:140) > [ 2.807537][ T2] kthreadd (kernel/kthread.c:400 kernel/kthread.c:746) > [ 2.807537][ T2] ? kthread_is_per_cpu (kernel/kthread.c:719) > [ 2.807537][ T2] ret_from_fork (arch/x86/entry/entry_64.S:314) > [ 2.807537][ T2] > It looks like task_cs() can only be used under rcu_read_lock(). I will update the patch to add that. Thanks, Longman