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 9B3A7C67871 for ; Thu, 27 Oct 2022 09:33:00 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233622AbiJ0Jc7 (ORCPT ); Thu, 27 Oct 2022 05:32:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:35110 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235394AbiJ0Jch (ORCPT ); Thu, 27 Oct 2022 05:32:37 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 569EF1A818; Thu, 27 Oct 2022 02:31:49 -0700 (PDT) From: John Ogness DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1666863107; 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: in-reply-to:in-reply-to:references:references; bh=plJs/SoOUqHYc5g+kkyWDkzzsy5zK9O4baDmIbyq7Js=; b=dmOqHK7dachlvzmMBDFuhv9vVD2VG33IsuAm/PWibmMAZZZ/7U4kFHX6/S38l8EBOD+Q/m 7qtIYJsmyv3VEkz/lMQl6Ljkw1fqvUVPI+kLdiCD3rBf33NSEVc9rYKu8QO3rWMxFC5LCB XT/4IGVGN0kmTqn4QbZ9VF+tYS7c9QoWN/LCrd2tMwRpAMtdIicetVjP72Hw+5Po9ye99k xTyjsUTXV35eaa7AwjL/maRZSEVLPVdcQf4hHnglePwyC3u7kMgnmR06z1J9+fjyn/y3NX gDJMkPk4KaCkW0ACkyabfmCNAbhtqjOlDVe+BYdIddSS7au0ctxQiC9XPv65TQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1666863107; 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: in-reply-to:in-reply-to:references:references; bh=plJs/SoOUqHYc5g+kkyWDkzzsy5zK9O4baDmIbyq7Js=; b=1vL3dRHaAKZqE8g2Z4EHSwlAM8OybK3JylpDRijEUTib+FOSWvkBQx8ugb40bjJGt0wewu qGeO6M5Ymp6dpIDw== To: paulmck@kernel.org Cc: Frederic Weisbecker , rcu@vger.kernel.org, linux-kernel@vger.kernel.org, kernel-team@fb.com, rostedt@goodmis.org, tglx@linutronix.de, pmladek@suse.com Subject: Re: [PATCH v2 rcu 0/8] NMI-safe SRCU reader API In-Reply-To: <20221024134727.GV5600@paulmck-ThinkPad-P17-Gen-1> References: <87ilkh0y52.fsf@jogness.linutronix.de> <20221018185936.GX5600@paulmck-ThinkPad-P17-Gen-1> <20221018215721.GA1716567@paulmck-ThinkPad-P17-Gen-1> <87pmeoawwe.fsf@jogness.linutronix.de> <20221019191418.GF5600@paulmck-ThinkPad-P17-Gen-1> <20221019220537.GA1234896@lothringen> <20221020222718.GA5600@paulmck-ThinkPad-P17-Gen-1> <87r0z1gy51.fsf@jogness.linutronix.de> <20221021184152.GO5600@paulmck-ThinkPad-P17-Gen-1> <87y1t5zqzz.fsf@jogness.linutronix.de> <20221024134727.GV5600@paulmck-ThinkPad-P17-Gen-1> Date: Thu, 27 Oct 2022 11:37:46 +0206 Message-ID: <874jvpehod.fsf@jogness.linutronix.de> MIME-Version: 1.0 Content-Type: text/plain Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org Hi Paul, I am running some tests using srcunmisafe.2022.10.21a and I am hitting the WARN_ONCE in srcu_check_nmi_safety(): [ 1.836703][ T1] rcu: Hierarchical SRCU implementation. [ 1.836707][ T1] rcu: Max phase no-delay instances is 1000. [ 1.836844][ T15] ------------[ cut here ]------------ [ 1.836846][ T15] CPU 0 old state 1 new state 2 [ 1.836885][ T15] WARNING: CPU: 0 PID: 15 at kernel/rcu/srcutree.c:652 srcu_check_nmi_safety+0x79/0x90 [ 1.836897][ T15] Modules linked in: [ 1.836903][ T15] CPU: 0 PID: 15 Comm: pr/bkl Not tainted 6.1.0-rc1+ #9 [ 1.836909][ T15] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.14.0-2 04/01/2014 [ 1.836912][ T15] RIP: 0010:srcu_check_nmi_safety+0x79/0x90 [ 1.836919][ T15] Code: d3 80 3d 9f 76 d3 01 00 75 e5 55 8b b0 c8 01 00 00 44 89 c1 48 c7 c7 d0 1f 87 82 c6 05 850 [ 1.836923][ T15] RSP: 0000:ffffc90000083e98 EFLAGS: 00010282 [ 1.836929][ T15] RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000 [ 1.836933][ T15] RDX: 0000000000000001 RSI: 0000000000000000 RDI: 00000000ffffffff [ 1.836936][ T15] RBP: ffffc90000083e98 R08: 0000000000000000 R09: 0000000000000001 [ 1.836940][ T15] R10: 0000000000000001 R11: 0000000000000000 R12: 0000000000000000 [ 1.836943][ T15] R13: ffffc90000013d70 R14: ffff888004073900 R15: 0000000000000000 [ 1.836946][ T15] FS: 0000000000000000(0000) GS:ffff888019600000(0000) knlGS:0000000000000000 [ 1.836951][ T15] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 1.836954][ T15] CR2: ffff888003c01000 CR3: 0000000002c22001 CR4: 0000000000370ef0 [ 1.836962][ T15] Call Trace: [ 1.836964][ T15] [ 1.836970][ T15] console_bkl_kthread_func+0x27a/0x590 [ 1.836981][ T15] ? _raw_spin_unlock_irqrestore+0x3c/0x60 [ 1.836998][ T15] ? console_fill_outbuf+0x210/0x210 [ 1.837003][ T15] kthread+0x108/0x130 [ 1.837012][ T15] ? kthread_complete_and_exit+0x20/0x20 [ 1.837025][ T15] ret_from_fork+0x1f/0x30 [ 1.837059][ T15] [ 1.837062][ T15] irq event stamp: 71 [ 1.837065][ T15] hardirqs last enabled at (73): [] vprintk_store+0x1b9/0x5e0 [ 1.837070][ T15] hardirqs last disabled at (74): [] vprintk_store+0x41b/0x5e0 [ 1.837075][ T15] softirqs last enabled at (0): [] copy_process+0x952/0x1dd0 [ 1.837081][ T15] softirqs last disabled at (0): [<0000000000000000>] 0x0 [ 1.837085][ T15] ---[ end trace 0000000000000000 ]--- [ 1.945054][ T12] Callback from call_rcu_tasks_rude() invoked. My code is calling srcu_read_lock_nmisafe() from task context, in a dedicated kthread. I am using DEFINE_STATIC_SRCU() to define/initialize the srcu struct. What does the warning imply? John Ogness