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 X-Spam-Level: X-Spam-Status: No, score=-5.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 8F79FC4332B for ; Tue, 24 Mar 2020 13:00:03 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 7F4BF20870 for ; Tue, 24 Mar 2020 13:00:02 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585054802; bh=ftHW6K2DFsXS/LfDVwMTnU8ysFh6LBvOe8/DLO8UHKI=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:List-ID: From; b=Jw3/bNzuoegHNSP8aO3K49iasTOdsv6EdbLuiEQoS5r2RgaqC76gXsDDj1W55qlY8 EkH3jLYuX5PJz8SFSCpYRSCARRCmaBpIIM1ls4UKfOI/mD91RMxq4I3/DEIZAcC1Ow 46lTEc99OCcuOfLKFPfDH+wVLlfjSZeYF5Z6ltzI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727446AbgCXNAB (ORCPT ); Tue, 24 Mar 2020 09:00:01 -0400 Received: from mail.kernel.org ([198.145.29.99]:50538 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727161AbgCXNAB (ORCPT ); Tue, 24 Mar 2020 09:00:01 -0400 Received: from paulmck-ThinkPad-P72.home (50-39-105-78.bvtn.or.frontiernet.net [50.39.105.78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id 535C32070A; Tue, 24 Mar 2020 13:00:00 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1585054800; bh=ftHW6K2DFsXS/LfDVwMTnU8ysFh6LBvOe8/DLO8UHKI=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=fs5PlPAYCmGz0kh9z4uz6nTDHF6IK/aV/K6BXhELTO3dZn0QIUt/rGZyPRRDMoC1W YtR5yNtqlbu5y5WYZlg6diyi9lbJVEiX834sTLfdsqyN5H5fMv02a5M6krcdcS4/Tt Qjb03KQNBjcp/AH9nJTxpaPoyUPhDVeZ8eHqw5pU= Received: by paulmck-ThinkPad-P72.home (Postfix, from userid 1000) id 23DBC35226BE; Tue, 24 Mar 2020 06:00:00 -0700 (PDT) Date: Tue, 24 Mar 2020 06:00:00 -0700 From: "Paul E. McKenney" To: Qais Yousef Cc: Davidlohr Bueso , Josh Triplett , linux-kernel@vger.kernel.org Subject: Re: Hit WARN_ON() in rcutorture.c:1055 Message-ID: <20200324130000.GT3199@paulmck-ThinkPad-P72> Reply-To: paulmck@kernel.org References: <20200323154309.nah44so2556ee56g@e107158-lin.cambridge.arm.com> <20200323155731.GK3199@paulmck-ThinkPad-P72> <20200323170609.w64xrfahd2snfz6h@e107158-lin.cambridge.arm.com> <20200323171751.GL3199@paulmck-ThinkPad-P72> <20200323174147.lneh4rp4tazhtm6x@e107158-lin.cambridge.arm.com> <20200323181010.GN3199@paulmck-ThinkPad-P72> <20200323182351.xr764b6wafzs6fse@e107158-lin.cambridge.arm.com> <20200323184437.GP3199@paulmck-ThinkPad-P72> <20200324113918.bnlnsip5crehxvlo@e107158-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20200324113918.bnlnsip5crehxvlo@e107158-lin> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Mar 24, 2020 at 11:39:19AM +0000, Qais Yousef wrote: > On 03/23/20 11:44, Paul E. McKenney wrote: > > > > > {register, unregister}_pm_notifier() don't seem to be too hard to use. > > > > > > > > That part is easy. It would also be necessary to find all the affected > > > > warnings in rcutorture and suppress them, not only during this time, > > > > but also for some period of time afterwards. Maybe this is the only one, > > > > but that would be surprising. ;-) > > > > > > Wouldn't be easier to just deinit/init()? ie: treat it like unload/load module. > > > > > > But you'll lose some info then that maybe you'd like to keep across > > > suspend/resume cycles. > > > > Hmmm... Are you running rcutorture as a loadable module or built into > > your kernel? In the latter case, it starts up automatically shortly > > after boot. > > Built-in. Sorry maybe I wasn't clear. I meant something like the attached. > Which still generates this warning, so yeah I get your point about suppressing > some warnings in the right places now. What my approach will be is to think through how to deal with this. It might be that I can come up with a simple strategy, and if so, I will make the changes. But yes, I never had considered this in any of my rcutorture design or implementation, so there is likely to be 15 years worth of bugs that would need to be fixed. Unless I can come up with something a bit more targeted. Which might happen. It sometimes has in past encounters with this sort of thing. ;-) Thanx, Paul > [ 48.898066] rcu-torture: Stopping rcu_torture_fwd_prog task > [ 48.908998] rcu-torture: Stopping rcu_torture_reader > [ 48.917052] rcu-torture: Stopping rcu_torture_fakewriter > [ 48.926987] ------------[ cut here ]------------ > [ 48.927025] WARNING: CPU: 4 PID: 261 at kernel/rcu/rcutorture.c:1085 rcu_torture_writer+0x49c/0xa90 > [ 48.927038] rcu-torture: Stopping rcu_torture_fakewriter > [ 48.927041] Modules linked in: > [ 48.927070] CPU: 4 PID: 261 Comm: rcu_torture_wri Not tainted 5.6.0-rc6-00002-g533440e608d2-dirty #540 > [ 48.927085] Hardware name: ARM Juno development board (r2) (DT) > [ 48.927103] pstate: 00000005 (nzcv daif -PAN -UAO) > [ 48.927124] pc : rcu_torture_writer+0x49c/0xa90 > [ 48.927144] lr : rcu_torture_writer+0x494/0xa90 > [ 48.927157] sp : ffff800018bfbde0 > [ 48.927172] x29: ffff800018bfbde0 x28: ffff80001426da58 > [ 48.927198] x27: ffff80001426cf08 x26: ffff80001426cf08 > [ 48.927224] x25: ffff8000121b5000 x24: 0000000000000001 > [ 48.927250] x23: ffff80001426d650 x22: ffff80001426b000 > [ 48.927275] x21: ffff800013439000 x20: 0000000000000001 > [ 48.927301] x19: ffff80001426c000 x18: 0000000000000000 > [ 48.927326] x17: 0000000000000000 x16: 0000000000000000 > [ 48.927351] x15: 0000000000000000 x14: 0000000000000000 > [ 48.927376] x13: 0000000000000000 x12: 0000000000000000 > [ 48.927401] x11: 00000000000001fa x10: 0000000000000000 > [ 48.927426] x9 : ffff800013a130a0 x8 : ffff0009757f0850 > [ 48.927450] x7 : 0000000000000000 x6 : ffff800018bfbcc0 > [ 48.927475] x5 : 0000000000000001 x4 : 0000000000000000 > [ 48.927499] x3 : 0000000000000080 x2 : 0000000000000000 > [ 48.927524] x1 : 0000000000000000 x0 : 0000000000000001 > [ 48.927548] Call trace: > [ 48.927569] rcu_torture_writer+0x49c/0xa90 > [ 48.927590] kthread+0x13c/0x140 > [ 48.927611] ret_from_fork+0x10/0x18 > [ 48.927627] irq event stamp: 34170 > [ 48.927654] hardirqs last enabled at (34169): [] __local_bh_enable_ip+0x98/0x148 > [ 48.927680] hardirqs last disabled at (34170): [] do_debug_exception+0x1a8/0x258 > [ 48.927702] softirqs last enabled at (34168): [] rcu_torture_free+0x84/0x98 > [ 48.927725] softirqs last disabled at (34166): [] rcu_torture_free+0x60/0x98 > [ 48.927740] ---[ end trace 57f88d092825f447 ]--- > > Thanks > > -- > Qais Yousef > diff --git a/kernel/rcu/rcutorture.c b/kernel/rcu/rcutorture.c > index 1aeecc165b21..defad882b236 100644 > --- a/kernel/rcu/rcutorture.c > +++ b/kernel/rcu/rcutorture.c > @@ -45,6 +45,7 @@ > #include > #include > #include > +#include > > #include "rcu.h" > > @@ -1628,7 +1629,7 @@ static int rcu_torture_stall(void *args) > } > > /* Spawn CPU-stall kthread, if stall_cpu specified. */ > -static int __init rcu_torture_stall_init(void) > +static int rcu_torture_stall_init(void) > { > if (stall_cpu <= 0) > return 0; > @@ -2008,7 +2009,7 @@ static int rcu_torture_fwd_prog(void *args) > } > > /* If forward-progress checking is requested and feasible, spawn the thread. */ > -static int __init rcu_torture_fwd_prog_init(void) > +static int rcu_torture_fwd_prog_init(void) > { > struct rcu_fwd *rfp; > > @@ -2359,7 +2360,7 @@ static void rcutorture_sync(void) > cur_ops->sync(); > } > > -static int __init > +static int > rcu_torture_init(void) > { > long i; > @@ -2549,5 +2550,47 @@ rcu_torture_init(void) > return firsterr; > } > > -module_init(rcu_torture_init); > -module_exit(rcu_torture_cleanup); > +static int rcu_torture_notify(struct notifier_block *nb, > + unsigned long mode, void *_unused) > +{ > + switch (mode) { > + case PM_HIBERNATION_PREPARE: > + case PM_SUSPEND_PREPARE: > + pr_info("Shutdodwn rcu torture.."); > + rcu_torture_cleanup(); > + break; > + > + case PM_POST_RESTORE: > + pr_info("Restart rcu torture.."); > + rcu_torture_init(); > + break; > + } > + > + return 0; > +} > + > +static struct notifier_block rcu_nb = { > + .notifier_call = rcu_torture_notify > +}; > + > +static int nb_failed; > + > +int rcu_torture_module_init(void) > +{ > + nb_failed = register_pm_notifier(&rcu_nb); > + if (nb_failed) > + pr_warn("Failed to register PM notifier"); > + > + return rcu_torture_init(); > +} > + > +void rcu_torture_module_exit(void) > +{ > + if (!nb_failed) > + unregister_pm_notifier(&rcu_nb); > + > + rcu_torture_cleanup(); > +} > + > +module_init(rcu_torture_module_init); > +module_exit(rcu_torture_module_exit);