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 AC9F7C25B04 for ; Thu, 15 Dec 2022 17:04:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230519AbiLOREp (ORCPT ); Thu, 15 Dec 2022 12:04:45 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53424 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231140AbiLOREO (ORCPT ); Thu, 15 Dec 2022 12:04:14 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 62E8E45EE5; Thu, 15 Dec 2022 09:03:03 -0800 (PST) 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 78447B81C03; Thu, 15 Dec 2022 17:02:58 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29F84C433EF; Thu, 15 Dec 2022 17:02:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1671123777; bh=rXDGlapaM3Azv+UeAte5jC1QsSGRIgALw2AzMtUQ5yM=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=obdOymEu7eYOm+NnFimhdy51BW3QRCfUvTDpOgaJm9kOeNOdBwUp45kJWX8TtpRAL YYmwoz3SYpyALGQ+cel1fpM3Y3pZ+Ect4HkLCm47GymFCD32O5bgjgjiwfWB4NOIQs hI9hwvR+Rl4aZun3Lmqd5ZCBRdbL6QKD7w8erSIlRy3Yk/Av5t+Vi1xUsD7kfLLzfg o7xpHYytkIBYpK//i1vHGqMAUNqJ6uvfCKWuFQbbQqrPZueuxFPbNSRdJI6AKJUTXg BNd+fJMADZiB87ZabxPSQxoQjUGR714yLJLhnDSqlz8xdZWpglfduQCVTHdsVRsPIG NH8R22LGq4xnw== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id C1C7B5C09D0; Thu, 15 Dec 2022 09:02:56 -0800 (PST) Date: Thu, 15 Dec 2022 09:02:56 -0800 From: "Paul E. McKenney" To: Steven Rostedt Cc: Masami Hiramatsu , LKML , Linux Trace Kernel , Andrew Morton , Mathieu Desnoyers Subject: Re: [PATCH] tracing: Do not synchronize freeing of trigger filter on boot up Message-ID: <20221215170256.GG4001@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20221213172429.7774f4ba@gandalf.local.home> <20221214084954.e759647a2f5f1a38bc78b371@kernel.org> <20221214200333.GA3208104@paulmck-ThinkPad-P17-Gen-1> <20221215100241.73a30da8@gandalf.local.home> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221215100241.73a30da8@gandalf.local.home> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Dec 15, 2022 at 10:02:41AM -0500, Steven Rostedt wrote: > On Wed, 14 Dec 2022 12:03:33 -0800 > "Paul E. McKenney" wrote: > > > > > Avoid calling the synchronization function when system_state is > > > > SYSTEM_BOOTING. > > > > > > Shouldn't this be done inside tracepoint_synchronize_unregister()? > > > Then, it will prevent similar warnings if we expand boot time feature. > > > > How about the following wide-spectrum fix within RCU_LOCKDEP_WARN()? > > Just in case there are ever additional issues of this sort? > > Adding more tracing command line parameters is triggering this more. I now > hit: Fair point, and apologies for the hassle. Any chance of getting an official "it is now late enough in boot to safely invoke lockdep" API? ;-) In the meantime, does the (untested and quite crude) patch at the end of this message help? Thanx, Paul > [ 0.213442] rcu: RCU calculated value of scheduler-enlistment delay is 25 jiffies. > [ 0.214653] rcu: Adjusting geometry for rcu_fanout_leaf=16, nr_cpu_ids=8 > [ 0.232023] ------------[ cut here ]------------ > [ 0.232704] WARNING: CPU: 0 PID: 0 at kernel/rcu/tree.c:1410 rcu_poll_gp_seq_start_unlocked+0x8a/0xa0 > [ 0.234241] Modules linked in: > [ 0.234715] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 6.1.0-rc6-test-00046-ga0ca17bfe724-dirty #63 > [ 0.236069] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.0-debian-1.16.0-4 04/01/2014 > [ 0.237549] RIP: 0010:rcu_poll_gp_seq_start_unlocked+0x8a/0xa0 > [ 0.238495] Code: 02 0f 0b 48 89 ee 5b 48 c7 c7 00 ca b1 b3 5d e9 cc 0f c1 00 65 8b 05 85 f3 dd 4d 85 c0 75 a1 65 8b 05 d6 f0 dd 4d 85 c0 75 96 <0f> 0b eb 92 5b 5d e9 eb 18 fc 00 66 66 2e 0f 1f 84 00 00 00 00 00 > [ 0.241433] RSP: 0000:ffffffffb3a03d28 EFLAGS: 00010046 > [ 0.242289] RAX: 0000000000000000 RBX: ffffffffb3bcfc48 RCX: 0000000000000001 > [ 0.243355] RDX: 0000000080000001 RSI: 0000000000000001 RDI: ffffffffb3bcfc48 > [ 0.244421] RBP: 0000000000000000 R08: ffff97a3c012b8f8 R09: fffffffffffffffe > [ 0.245569] R10: ffffffffb3a03e78 R11: 00000000ffffffff R12: 0000000000000040 > [ 0.246752] R13: ffffffffb3a30500 R14: ffffffffb3be6180 R15: ffff97a3c0355d10 > [ 0.247826] FS: 0000000000000000(0000) GS:ffff97a537c00000(0000) knlGS:0000000000000000 > [ 0.249084] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 0.250012] CR2: ffff97a51e201000 CR3: 000000025c826001 CR4: 00000000000606b0 > [ 0.251122] Call Trace: > [ 0.251491] > [ 0.251810] synchronize_rcu+0xb6/0x1e0 > [ 0.252393] ? smp_call_function_many_cond+0x36d/0x3b0 > [ 0.253243] ? enable_trace_buffered_event+0x10/0x10 > [ 0.254021] trace_buffered_event_disable+0x7c/0x140 > [ 0.254786] __ftrace_event_enable_disable+0x11c/0x250 > [ 0.255559] __ftrace_set_clr_event_nolock+0xe3/0x130 > [ 0.256321] ftrace_set_clr_event+0x9a/0xe0 > [ 0.256976] early_enable_events+0x64/0xa8 > [ 0.257647] trace_event_init+0xd6/0x2dd > [ 0.258305] start_kernel+0x760/0x9e0 > [ 0.258862] secondary_startup_64_no_verify+0xe5/0xeb > [ 0.259634] > [ 0.259966] irq event stamp: 0 > [ 0.260427] hardirqs last enabled at (0): [<0000000000000000>] 0x0 > [ 0.261448] hardirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 0.262424] softirqs last enabled at (0): [<0000000000000000>] 0x0 > [ 0.263402] softirqs last disabled at (0): [<0000000000000000>] 0x0 > [ 0.264345] ---[ end trace 0000000000000000 ]--- > [ 0.265088] ------------[ cut here ]------------ > > Where kernel/rcu/tree.c:1410 is at: > > // Make the polled API aware of the beginning of a grace period, but > // where caller does not hold the root rcu_node structure's lock. > static void rcu_poll_gp_seq_start_unlocked(unsigned long *snap) > { > unsigned long flags; > struct rcu_node *rnp = rcu_get_root(); > > if (rcu_init_invoked()) { > lockdep_assert_irqs_enabled(); <<-------------- 1410 > raw_spin_lock_irqsave_rcu_node(rnp, flags); > } > rcu_poll_gp_seq_start(snap); > if (rcu_init_invoked()) > raw_spin_unlock_irqrestore_rcu_node(rnp, flags); > } diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c index ee8a6a711719a..af8c99920e1a4 100644 --- a/kernel/rcu/tree.c +++ b/kernel/rcu/tree.c @@ -151,7 +151,6 @@ static void sync_sched_exp_online_cleanup(int cpu); static void check_cb_ovld_locked(struct rcu_data *rdp, struct rcu_node *rnp); static bool rcu_rdp_is_offloaded(struct rcu_data *rdp); static bool rcu_rdp_cpu_online(struct rcu_data *rdp); -static bool rcu_init_invoked(void); static void rcu_cleanup_dead_rnp(struct rcu_node *rnp_leaf); static void rcu_init_new_rnp(struct rcu_node *rnp_leaf); @@ -1314,7 +1313,7 @@ static void rcu_poll_gp_seq_start(unsigned long *snap) { struct rcu_node *rnp = rcu_get_root(); - if (rcu_init_invoked()) + if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE) raw_lockdep_assert_held_rcu_node(rnp); // If RCU was idle, note beginning of GP. @@ -1330,7 +1329,7 @@ static void rcu_poll_gp_seq_end(unsigned long *snap) { struct rcu_node *rnp = rcu_get_root(); - if (rcu_init_invoked()) + if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE) raw_lockdep_assert_held_rcu_node(rnp); // If the previously noted GP is still in effect, record the @@ -1352,12 +1351,12 @@ static void rcu_poll_gp_seq_start_unlocked(unsigned long *snap) unsigned long flags; struct rcu_node *rnp = rcu_get_root(); - if (rcu_init_invoked()) { + if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE) { lockdep_assert_irqs_enabled(); raw_spin_lock_irqsave_rcu_node(rnp, flags); } rcu_poll_gp_seq_start(snap); - if (rcu_init_invoked()) + if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE) raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } @@ -1368,12 +1367,12 @@ static void rcu_poll_gp_seq_end_unlocked(unsigned long *snap) unsigned long flags; struct rcu_node *rnp = rcu_get_root(); - if (rcu_init_invoked()) { + if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE) { lockdep_assert_irqs_enabled(); raw_spin_lock_irqsave_rcu_node(rnp, flags); } rcu_poll_gp_seq_end(snap); - if (rcu_init_invoked()) + if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE) raw_spin_unlock_irqrestore_rcu_node(rnp, flags); } @@ -4042,13 +4041,6 @@ EXPORT_SYMBOL_GPL(rcu_lockdep_current_cpu_online); #endif /* #if defined(CONFIG_PROVE_RCU) && defined(CONFIG_HOTPLUG_CPU) */ -// Has rcu_init() been invoked? This is used (for example) to determine -// whether spinlocks may be acquired safely. -static bool rcu_init_invoked(void) -{ - return !!rcu_state.n_online_cpus; -} - /* * Near the end of the offline process. Trace the fact that this CPU * is going offline. diff --git a/kernel/rcu/tree_exp.h b/kernel/rcu/tree_exp.h index ed6c3cce28f23..26146530d48f9 100644 --- a/kernel/rcu/tree_exp.h +++ b/kernel/rcu/tree_exp.h @@ -1019,14 +1019,14 @@ unsigned long start_poll_synchronize_rcu_expedited(void) s = get_state_synchronize_rcu(); rdp = per_cpu_ptr(&rcu_data, raw_smp_processor_id()); rnp = rdp->mynode; - if (rcu_init_invoked()) + if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE) raw_spin_lock_irqsave(&rnp->exp_poll_lock, flags); if (!poll_state_synchronize_rcu(s)) { rnp->exp_seq_poll_rq = s; - if (rcu_init_invoked()) + if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE) queue_work(rcu_gp_wq, &rnp->exp_poll_wq); } - if (rcu_init_invoked()) + if (rcu_scheduler_active != RCU_SCHEDULER_INACTIVE) raw_spin_unlock_irqrestore(&rnp->exp_poll_lock, flags); return s;