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 2FB03C19F2C for ; Fri, 29 Jul 2022 15:28:37 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237734AbiG2P2d (ORCPT ); Fri, 29 Jul 2022 11:28:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58528 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S237632AbiG2P2Y (ORCPT ); Fri, 29 Jul 2022 11:28:24 -0400 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2149A86C34; Fri, 29 Jul 2022 08:28:17 -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 1E2C4B82846; Fri, 29 Jul 2022 15:28:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C3C2BC433C1; Fri, 29 Jul 2022 15:28:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659108493; bh=+Eu1+NpdMQSxhSpBOHg1xq9IY5RE5+jGBaKhcxBU/fw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=SYC3Dsw++Jo9/onL7ZbEg1e34NjAkGJ0/LEyzxxtRyARi5tsRhnhMCBXpA48hlrbx /ygCpipyirN70BTWI+O7BPw3KEXhwiaeJ1toIS9f4x8NNUrtDb0g9IXD0fU2Bmoo6M w/YCbZ5sds6/EqIKdGN13GNgPIYzv0deYvecUifHVmZHvmvFFPvpCRqJ8szO8EVscM zHVucD9HNGWsnSLNuXErgrHHYht/KZ+I5xQvurQSs2gAeRSzLQTzOZZkq+fQyiif2B dBwd0T3KOaUJi1JScRgdDFB1nTqlfa6EEzGGbx1ADBkWPp5B2oyL/vemt0EQW8/A3l tsRJX93dX43kQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 77B5C5C033E; Fri, 29 Jul 2022 08:28:13 -0700 (PDT) Date: Fri, 29 Jul 2022 08:28:13 -0700 From: "Paul E. McKenney" To: Michel Lespinasse Cc: Peter Zijlstra , rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, boris.ostrovsky@oracle.com, chris@zankel.net, jcmvbkbc@gmail.com, rafael@kernel.org, lenb@kernel.org, pavel@ucw.cz, gregkh@linuxfoundation.org, mturquette@baylibre.com, sboyd@kernel.org, daniel.lezcano@linaro.org, lpieralisi@kernel.org, sudeep.holla@arm.com, agross@kernel.org, bjorn.andersson@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, rostedt@goodmis.org, pmladek@suse.com, senozhatsky@chromium.org, john.ogness@linutronix.de, frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-perf-users@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org, rh0@fb.com Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE Message-ID: <20220729152813.GA3579395@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org References: <20220608142723.103523089@infradead.org> <20220608144516.172460444@infradead.org> <20220725194306.GA14746@lespinasse.org> <20220728172053.GA3607379@paulmck-ThinkPad-P17-Gen-1> <20220729102458.GA1695@lespinasse.org> <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> Precedence: bulk List-ID: X-Mailing-List: linux-sh@vger.kernel.org Or better yet, try the patch that Rafael proposed. ;-) Thanx, Paul On Fri, Jul 29, 2022 at 08:26:22AM -0700, Paul E. McKenney wrote: > On Fri, Jul 29, 2022 at 03:24:58AM -0700, Michel Lespinasse wrote: > > On Thu, Jul 28, 2022 at 10:20:53AM -0700, Paul E. McKenney wrote: > > > On Mon, Jul 25, 2022 at 12:43:06PM -0700, Michel Lespinasse wrote: > > > > On Wed, Jun 08, 2022 at 04:27:27PM +0200, Peter Zijlstra wrote: > > > > > Commit c227233ad64c ("intel_idle: enable interrupts before C1 on > > > > > Xeons") wrecked intel_idle in two ways: > > > > > > > > > > - must not have tracing in idle functions > > > > > - must return with IRQs disabled > > > > > > > > > > Additionally, it added a branch for no good reason. > > > > > > > > > > Fixes: c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons") > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > > > > > > After this change was introduced, I am seeing "WARNING: suspicious RCU > > > > usage" when booting a kernel with debug options compiled in. Please > > > > see the attached dmesg output. The issue starts with commit 32d4fd5751ea > > > > and is still present in v5.19-rc8. > > > > > > > > I'm not sure, is this too late to fix or revert in v5.19 final ? > > > > > > I finally got a chance to take a quick look at this. > > > > > > The rcu_eqs_exit() function is making a lockdep complaint about > > > being invoked with interrupts enabled. This function is called from > > > rcu_idle_exit(), which is an expected code path from cpuidle_enter_state() > > > via its call to rcu_idle_exit(). Except that rcu_idle_exit() disables > > > interrupts before invoking rcu_eqs_exit(). > > > > > > The only other call to rcu_idle_exit() does not disable interrupts, > > > but it is via rcu_user_exit(), which would be a very odd choice for > > > cpuidle_enter_state(). > > > > > > It seems unlikely, but it might be that it is the use of local_irq_save() > > > instead of raw_local_irq_save() within rcu_idle_exit() that is causing > > > the trouble. If this is the case, then the commit shown below would > > > help. Note that this commit removes the warning from lockdep, so it > > > is necessary to build the kernel with CONFIG_RCU_EQS_DEBUG=y to enable > > > equivalent debugging. > > > > > > Could you please try your test with the -rce commit shown below applied? > > > > Thanks for looking into it. > > And thank you for trying this shot in the dark! > > > After checking out Peter's commit 32d4fd5751ea, > > cherry picking your commit ed4ae5eff4b3, > > and setting CONFIG_RCU_EQS_DEBUG=y in addition of my usual debug config, > > I am now seeing this a few seconds into the boot: > > > > [ 3.010650] ------------[ cut here ]------------ > > [ 3.010651] WARNING: CPU: 0 PID: 0 at kernel/sched/clock.c:397 sched_clock_tick+0x27/0x60 > > And this is again a complaint about interrupts not being disabled. > > But it does appear that the problem was the lockdep complaint, and > eliminating that did take care of part of the problem. But lockdep > remained enabled, and you therefore hit the next complaint. > > > [ 3.010657] Modules linked in: > > [ 3.010660] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc1-test-00005-g1be22fea0611 #1 > > [ 3.010662] Hardware name: LENOVO 30BFS44D00/1036, BIOS S03KT51A 01/17/2022 > > [ 3.010663] RIP: 0010:sched_clock_tick+0x27/0x60 > > The most straightforward way to get to sched_clock_tick() from > cpuidle_enter_state() is via the call to sched_clock_idle_wakeup_event(). > > Except that it disables interrupts before invoking sched_clock_tick(). > > > [ 3.010665] Code: 1f 40 00 53 eb 02 5b c3 66 90 8b 05 2f c3 40 01 85 c0 74 18 65 8b 05 60 88 8f 4e 85 c0 75 0d 65 8b 05 a9 85 8f 4e 85 c0 74 02 <0f> 0b e8 e2 6c 89 00 48 c7 c3 40 d5 02 00 > > 89 c0 48 03 1c c5 c0 98 > > [ 3.010667] RSP: 0000:ffffffffb2803e28 EFLAGS: 00010002 > > [ 3.010670] RAX: 0000000000000001 RBX: ffffc8ce7fa07060 RCX: 0000000000000001 > > [ 3.010671] RDX: 0000000000000000 RSI: ffffffffb268dd21 RDI: ffffffffb269ab13 > > [ 3.010673] RBP: 0000000000000001 R08: ffffffffffc300d5 R09: 000000000002be80 > > [ 3.010674] R10: 000003625b53183a R11: ffffa012b802b7a4 R12: ffffffffb2aa9e80 > > [ 3.010675] R13: ffffffffb2aa9e00 R14: 0000000000000001 R15: 0000000000000000 > > [ 3.010677] FS: 0000000000000000(0000) GS:ffffa012b8000000(0000) knlGS:0000000000000000 > > [ 3.010678] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 3.010680] CR2: ffffa012f81ff000 CR3: 0000000c99612001 CR4: 00000000003706f0 > > [ 3.010681] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > [ 3.010682] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > [ 3.010683] Call Trace: > > [ 3.010685] > > [ 3.010688] cpuidle_enter_state+0xb7/0x4b0 > > [ 3.010694] cpuidle_enter+0x29/0x40 > > [ 3.010697] do_idle+0x1d4/0x210 > > [ 3.010702] cpu_startup_entry+0x19/0x20 > > [ 3.010704] rest_init+0x117/0x1a0 > > [ 3.010708] arch_call_rest_init+0xa/0x10 > > [ 3.010711] start_kernel+0x6d8/0x6ff > > [ 3.010716] secondary_startup_64_no_verify+0xce/0xdb > > [ 3.010728] > > [ 3.010729] irq event stamp: 44179 > > [ 3.010730] hardirqs last enabled at (44179): [] asm_sysvec_apic_timer_interrupt+0x1b/0x20 > > [ 3.010734] hardirqs last disabled at (44177): [] __do_softirq+0x3f0/0x498 > > [ 3.010736] softirqs last enabled at (44178): [] __do_softirq+0x332/0x498 > > [ 3.010738] softirqs last disabled at (44171): [] irq_exit_rcu+0xab/0xf0 > > [ 3.010741] ---[ end trace 0000000000000000 ]--- > > Would you be willing to try another shot in the dark, but untested > this time? I freely admit that this is getting strange. > > Thanx, Paul > > ------------------------------------------------------------------------ > > diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c > index e374c0c923dae..279f557bf60bb 100644 > --- a/kernel/sched/clock.c > +++ b/kernel/sched/clock.c > @@ -394,7 +394,7 @@ notrace void sched_clock_tick(void) > if (!static_branch_likely(&sched_clock_running)) > return; > > - lockdep_assert_irqs_disabled(); > + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled()); > > scd = this_scd(); > __scd_stamp(scd); 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id A2646C00144 for ; Fri, 29 Jul 2022 15:28:23 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:Reply-To:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=xSzJmW2dD5sDf9NmAi58PsdxCiv4EdZ70I61wDOrhEo=; b=hHvL/j2E3gs76q gjQ9xlb4SO60mR/F5FaEJxVN5VLG8fDlRCXeovZ7vBg7pIiVQ53P4E5cvmZUZZZ3n7QdRFfWSHaC9 kNsif9blw93YJIpca9eFBgnBeKl+woM4yrnA3kiHZuwqrKCBxy7EiGhYfk9mPE06ywdVDY919IZIY Vitrxza5blN+IGbj+aolzl1VaRT/0KUVtK3Bbnfyimq2K/THIiJIugOxDCSDUzroHknxDfc421TYQ DZjNYr8ubM4rOF7foX9iD50eLsCwcl+uaTCaoNNUBeCBhHVuYqtHy9ZTGq7V75yW0SxNeY05BV7PX foNwJY4XhtLD6ZF9mozA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oHRuW-005toJ-TE; Fri, 29 Jul 2022 15:28:20 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oHRuS-005tlG-BV; Fri, 29 Jul 2022 15:28:18 +0000 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 0B522B82844; Fri, 29 Jul 2022 15:28:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1F1EC433D6; Fri, 29 Jul 2022 15:28:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659108493; bh=+Eu1+NpdMQSxhSpBOHg1xq9IY5RE5+jGBaKhcxBU/fw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=SYC3Dsw++Jo9/onL7ZbEg1e34NjAkGJ0/LEyzxxtRyARi5tsRhnhMCBXpA48hlrbx /ygCpipyirN70BTWI+O7BPw3KEXhwiaeJ1toIS9f4x8NNUrtDb0g9IXD0fU2Bmoo6M w/YCbZ5sds6/EqIKdGN13GNgPIYzv0deYvecUifHVmZHvmvFFPvpCRqJ8szO8EVscM zHVucD9HNGWsnSLNuXErgrHHYht/KZ+I5xQvurQSs2gAeRSzLQTzOZZkq+fQyiif2B dBwd0T3KOaUJi1JScRgdDFB1nTqlfa6EEzGGbx1ADBkWPp5B2oyL/vemt0EQW8/A3l tsRJX93dX43kQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 77B5C5C033E; Fri, 29 Jul 2022 08:28:13 -0700 (PDT) Date: Fri, 29 Jul 2022 08:28:13 -0700 From: "Paul E. McKenney" To: Michel Lespinasse Cc: Peter Zijlstra , rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, boris.ostrovsky@oracle.com, chris@zankel.net, jcmvbkbc@gmail.com, rafael@kernel.org, lenb@kernel.org, pavel@ucw.cz, gregkh@linuxfoundation.org, mturquette@baylibre.com, sboyd@kernel.org, daniel.lezcano@linaro.org, lpieralisi@kernel.org, sudeep.holla@arm.com, agross@kernel.org, bjorn.andersson@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, rostedt@goodmis.org, pmladek@suse.com, senozhatsky@chromium.org, john.ogness@linutronix.de, frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-perf-users@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org, rh0@fb.com Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE Message-ID: <20220729152813.GA3579395@paulmck-ThinkPad-P17-Gen-1> References: <20220608142723.103523089@infradead.org> <20220608144516.172460444@infradead.org> <20220725194306.GA14746@lespinasse.org> <20220728172053.GA3607379@paulmck-ThinkPad-P17-Gen-1> <20220729102458.GA1695@lespinasse.org> <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220729_082816_692159_5F1766D5 X-CRM114-Status: GOOD ( 47.43 ) X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: paulmck@kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+linux-snps-arc=archiver.kernel.org@lists.infradead.org Or better yet, try the patch that Rafael proposed. ;-) Thanx, Paul On Fri, Jul 29, 2022 at 08:26:22AM -0700, Paul E. McKenney wrote: > On Fri, Jul 29, 2022 at 03:24:58AM -0700, Michel Lespinasse wrote: > > On Thu, Jul 28, 2022 at 10:20:53AM -0700, Paul E. McKenney wrote: > > > On Mon, Jul 25, 2022 at 12:43:06PM -0700, Michel Lespinasse wrote: > > > > On Wed, Jun 08, 2022 at 04:27:27PM +0200, Peter Zijlstra wrote: > > > > > Commit c227233ad64c ("intel_idle: enable interrupts before C1 on > > > > > Xeons") wrecked intel_idle in two ways: > > > > > > > > > > - must not have tracing in idle functions > > > > > - must return with IRQs disabled > > > > > > > > > > Additionally, it added a branch for no good reason. > > > > > > > > > > Fixes: c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons") > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > > > > > > After this change was introduced, I am seeing "WARNING: suspicious RCU > > > > usage" when booting a kernel with debug options compiled in. Please > > > > see the attached dmesg output. The issue starts with commit 32d4fd5751ea > > > > and is still present in v5.19-rc8. > > > > > > > > I'm not sure, is this too late to fix or revert in v5.19 final ? > > > > > > I finally got a chance to take a quick look at this. > > > > > > The rcu_eqs_exit() function is making a lockdep complaint about > > > being invoked with interrupts enabled. This function is called from > > > rcu_idle_exit(), which is an expected code path from cpuidle_enter_state() > > > via its call to rcu_idle_exit(). Except that rcu_idle_exit() disables > > > interrupts before invoking rcu_eqs_exit(). > > > > > > The only other call to rcu_idle_exit() does not disable interrupts, > > > but it is via rcu_user_exit(), which would be a very odd choice for > > > cpuidle_enter_state(). > > > > > > It seems unlikely, but it might be that it is the use of local_irq_save() > > > instead of raw_local_irq_save() within rcu_idle_exit() that is causing > > > the trouble. If this is the case, then the commit shown below would > > > help. Note that this commit removes the warning from lockdep, so it > > > is necessary to build the kernel with CONFIG_RCU_EQS_DEBUG=y to enable > > > equivalent debugging. > > > > > > Could you please try your test with the -rce commit shown below applied? > > > > Thanks for looking into it. > > And thank you for trying this shot in the dark! > > > After checking out Peter's commit 32d4fd5751ea, > > cherry picking your commit ed4ae5eff4b3, > > and setting CONFIG_RCU_EQS_DEBUG=y in addition of my usual debug config, > > I am now seeing this a few seconds into the boot: > > > > [ 3.010650] ------------[ cut here ]------------ > > [ 3.010651] WARNING: CPU: 0 PID: 0 at kernel/sched/clock.c:397 sched_clock_tick+0x27/0x60 > > And this is again a complaint about interrupts not being disabled. > > But it does appear that the problem was the lockdep complaint, and > eliminating that did take care of part of the problem. But lockdep > remained enabled, and you therefore hit the next complaint. > > > [ 3.010657] Modules linked in: > > [ 3.010660] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc1-test-00005-g1be22fea0611 #1 > > [ 3.010662] Hardware name: LENOVO 30BFS44D00/1036, BIOS S03KT51A 01/17/2022 > > [ 3.010663] RIP: 0010:sched_clock_tick+0x27/0x60 > > The most straightforward way to get to sched_clock_tick() from > cpuidle_enter_state() is via the call to sched_clock_idle_wakeup_event(). > > Except that it disables interrupts before invoking sched_clock_tick(). > > > [ 3.010665] Code: 1f 40 00 53 eb 02 5b c3 66 90 8b 05 2f c3 40 01 85 c0 74 18 65 8b 05 60 88 8f 4e 85 c0 75 0d 65 8b 05 a9 85 8f 4e 85 c0 74 02 <0f> 0b e8 e2 6c 89 00 48 c7 c3 40 d5 02 00 > > 89 c0 48 03 1c c5 c0 98 > > [ 3.010667] RSP: 0000:ffffffffb2803e28 EFLAGS: 00010002 > > [ 3.010670] RAX: 0000000000000001 RBX: ffffc8ce7fa07060 RCX: 0000000000000001 > > [ 3.010671] RDX: 0000000000000000 RSI: ffffffffb268dd21 RDI: ffffffffb269ab13 > > [ 3.010673] RBP: 0000000000000001 R08: ffffffffffc300d5 R09: 000000000002be80 > > [ 3.010674] R10: 000003625b53183a R11: ffffa012b802b7a4 R12: ffffffffb2aa9e80 > > [ 3.010675] R13: ffffffffb2aa9e00 R14: 0000000000000001 R15: 0000000000000000 > > [ 3.010677] FS: 0000000000000000(0000) GS:ffffa012b8000000(0000) knlGS:0000000000000000 > > [ 3.010678] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 3.010680] CR2: ffffa012f81ff000 CR3: 0000000c99612001 CR4: 00000000003706f0 > > [ 3.010681] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > [ 3.010682] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > [ 3.010683] Call Trace: > > [ 3.010685] > > [ 3.010688] cpuidle_enter_state+0xb7/0x4b0 > > [ 3.010694] cpuidle_enter+0x29/0x40 > > [ 3.010697] do_idle+0x1d4/0x210 > > [ 3.010702] cpu_startup_entry+0x19/0x20 > > [ 3.010704] rest_init+0x117/0x1a0 > > [ 3.010708] arch_call_rest_init+0xa/0x10 > > [ 3.010711] start_kernel+0x6d8/0x6ff > > [ 3.010716] secondary_startup_64_no_verify+0xce/0xdb > > [ 3.010728] > > [ 3.010729] irq event stamp: 44179 > > [ 3.010730] hardirqs last enabled at (44179): [] asm_sysvec_apic_timer_interrupt+0x1b/0x20 > > [ 3.010734] hardirqs last disabled at (44177): [] __do_softirq+0x3f0/0x498 > > [ 3.010736] softirqs last enabled at (44178): [] __do_softirq+0x332/0x498 > > [ 3.010738] softirqs last disabled at (44171): [] irq_exit_rcu+0xab/0xf0 > > [ 3.010741] ---[ end trace 0000000000000000 ]--- > > Would you be willing to try another shot in the dark, but untested > this time? I freely admit that this is getting strange. > > Thanx, Paul > > ------------------------------------------------------------------------ > > diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c > index e374c0c923dae..279f557bf60bb 100644 > --- a/kernel/sched/clock.c > +++ b/kernel/sched/clock.c > @@ -394,7 +394,7 @@ notrace void sched_clock_tick(void) > if (!static_branch_likely(&sched_clock_running)) > return; > > - lockdep_assert_irqs_disabled(); > + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled()); > > scd = this_scd(); > __scd_stamp(scd); _______________________________________________ linux-snps-arc mailing list linux-snps-arc@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-snps-arc 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 44F32C00144 for ; Fri, 29 Jul 2022 17:32:53 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:Reply-To:List-Subscribe:List-Help: List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=3/l9sn1TOU431vmx2Ak8iX2bqqdpRpFYTAIIPNIQR/U=; b=IRKJrLvVfXGuDG /dMrjYotdfwpmZMN68RdReV/wXe8lUiMnEahyyYvu6WZmUaFEDKyMkZObESdlCJJ76FzV7rA7kIqa MRp+x416dJqcw2rrH3XypwmGSrHhv/wpVC/21icvdIIpMPHNb7d2NueHOCXNGe/+1UfZCjSWbDM+i Y3C9ZwL/C6zY4GJ6yhzl4NgHSJtZKNF4e/KDyFIKOmZo6cEDbA3Iom2SN66Ev4Kv/Chf65auftcD0 Xv9LHRBG+kfHAAoaBkRLXy+N7KJlD3GmLCbtyKZeWmFsrq6YoH2SbAEGMSiUgZT7BcfrbJkOuLnFP aA8kqjubXLqIWtbrJ5dg==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1oHTqp-008KYi-8Q; Fri, 29 Jul 2022 17:32:39 +0000 Received: from ams.source.kernel.org ([2604:1380:4601:e00::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1oHRuS-005tlG-BV; Fri, 29 Jul 2022 15:28:18 +0000 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 0B522B82844; Fri, 29 Jul 2022 15:28:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1F1EC433D6; Fri, 29 Jul 2022 15:28:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659108493; bh=+Eu1+NpdMQSxhSpBOHg1xq9IY5RE5+jGBaKhcxBU/fw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=SYC3Dsw++Jo9/onL7ZbEg1e34NjAkGJ0/LEyzxxtRyARi5tsRhnhMCBXpA48hlrbx /ygCpipyirN70BTWI+O7BPw3KEXhwiaeJ1toIS9f4x8NNUrtDb0g9IXD0fU2Bmoo6M w/YCbZ5sds6/EqIKdGN13GNgPIYzv0deYvecUifHVmZHvmvFFPvpCRqJ8szO8EVscM zHVucD9HNGWsnSLNuXErgrHHYht/KZ+I5xQvurQSs2gAeRSzLQTzOZZkq+fQyiif2B dBwd0T3KOaUJi1JScRgdDFB1nTqlfa6EEzGGbx1ADBkWPp5B2oyL/vemt0EQW8/A3l tsRJX93dX43kQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 77B5C5C033E; Fri, 29 Jul 2022 08:28:13 -0700 (PDT) Date: Fri, 29 Jul 2022 08:28:13 -0700 From: "Paul E. McKenney" To: Michel Lespinasse Cc: Peter Zijlstra , rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, boris.ostrovsky@oracle.com, chris@zankel.net, jcmvbkbc@gmail.com, rafael@kernel.org, lenb@kernel.org, pavel@ucw.cz, gregkh@linuxfoundation.org, mturquette@baylibre.com, sboyd@kernel.org, daniel.lezcano@linaro.org, lpieralisi@kernel.org, sudeep.holla@arm.com, agross@kernel.org, bjorn.andersson@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, rostedt@goodmis.org, pmladek@suse.com, senozhatsky@chromium.org, john.ogness@linutronix.de, frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-perf-users@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org, rh0@fb.com Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE Message-ID: <20220729152813.GA3579395@paulmck-ThinkPad-P17-Gen-1> References: <20220608142723.103523089@infradead.org> <20220608144516.172460444@infradead.org> <20220725194306.GA14746@lespinasse.org> <20220728172053.GA3607379@paulmck-ThinkPad-P17-Gen-1> <20220729102458.GA1695@lespinasse.org> <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220729_082816_692159_5F1766D5 X-CRM114-Status: GOOD ( 47.43 ) X-Mailman-Approved-At: Fri, 29 Jul 2022 10:19:48 -0700 X-BeenThere: linux-riscv@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: paulmck@kernel.org Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-riscv" Errors-To: linux-riscv-bounces+linux-riscv=archiver.kernel.org@lists.infradead.org Or better yet, try the patch that Rafael proposed. ;-) Thanx, Paul On Fri, Jul 29, 2022 at 08:26:22AM -0700, Paul E. McKenney wrote: > On Fri, Jul 29, 2022 at 03:24:58AM -0700, Michel Lespinasse wrote: > > On Thu, Jul 28, 2022 at 10:20:53AM -0700, Paul E. McKenney wrote: > > > On Mon, Jul 25, 2022 at 12:43:06PM -0700, Michel Lespinasse wrote: > > > > On Wed, Jun 08, 2022 at 04:27:27PM +0200, Peter Zijlstra wrote: > > > > > Commit c227233ad64c ("intel_idle: enable interrupts before C1 on > > > > > Xeons") wrecked intel_idle in two ways: > > > > > > > > > > - must not have tracing in idle functions > > > > > - must return with IRQs disabled > > > > > > > > > > Additionally, it added a branch for no good reason. > > > > > > > > > > Fixes: c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons") > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > > > > > > After this change was introduced, I am seeing "WARNING: suspicious RCU > > > > usage" when booting a kernel with debug options compiled in. Please > > > > see the attached dmesg output. The issue starts with commit 32d4fd5751ea > > > > and is still present in v5.19-rc8. > > > > > > > > I'm not sure, is this too late to fix or revert in v5.19 final ? > > > > > > I finally got a chance to take a quick look at this. > > > > > > The rcu_eqs_exit() function is making a lockdep complaint about > > > being invoked with interrupts enabled. This function is called from > > > rcu_idle_exit(), which is an expected code path from cpuidle_enter_state() > > > via its call to rcu_idle_exit(). Except that rcu_idle_exit() disables > > > interrupts before invoking rcu_eqs_exit(). > > > > > > The only other call to rcu_idle_exit() does not disable interrupts, > > > but it is via rcu_user_exit(), which would be a very odd choice for > > > cpuidle_enter_state(). > > > > > > It seems unlikely, but it might be that it is the use of local_irq_save() > > > instead of raw_local_irq_save() within rcu_idle_exit() that is causing > > > the trouble. If this is the case, then the commit shown below would > > > help. Note that this commit removes the warning from lockdep, so it > > > is necessary to build the kernel with CONFIG_RCU_EQS_DEBUG=y to enable > > > equivalent debugging. > > > > > > Could you please try your test with the -rce commit shown below applied? > > > > Thanks for looking into it. > > And thank you for trying this shot in the dark! > > > After checking out Peter's commit 32d4fd5751ea, > > cherry picking your commit ed4ae5eff4b3, > > and setting CONFIG_RCU_EQS_DEBUG=y in addition of my usual debug config, > > I am now seeing this a few seconds into the boot: > > > > [ 3.010650] ------------[ cut here ]------------ > > [ 3.010651] WARNING: CPU: 0 PID: 0 at kernel/sched/clock.c:397 sched_clock_tick+0x27/0x60 > > And this is again a complaint about interrupts not being disabled. > > But it does appear that the problem was the lockdep complaint, and > eliminating that did take care of part of the problem. But lockdep > remained enabled, and you therefore hit the next complaint. > > > [ 3.010657] Modules linked in: > > [ 3.010660] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc1-test-00005-g1be22fea0611 #1 > > [ 3.010662] Hardware name: LENOVO 30BFS44D00/1036, BIOS S03KT51A 01/17/2022 > > [ 3.010663] RIP: 0010:sched_clock_tick+0x27/0x60 > > The most straightforward way to get to sched_clock_tick() from > cpuidle_enter_state() is via the call to sched_clock_idle_wakeup_event(). > > Except that it disables interrupts before invoking sched_clock_tick(). > > > [ 3.010665] Code: 1f 40 00 53 eb 02 5b c3 66 90 8b 05 2f c3 40 01 85 c0 74 18 65 8b 05 60 88 8f 4e 85 c0 75 0d 65 8b 05 a9 85 8f 4e 85 c0 74 02 <0f> 0b e8 e2 6c 89 00 48 c7 c3 40 d5 02 00 > > 89 c0 48 03 1c c5 c0 98 > > [ 3.010667] RSP: 0000:ffffffffb2803e28 EFLAGS: 00010002 > > [ 3.010670] RAX: 0000000000000001 RBX: ffffc8ce7fa07060 RCX: 0000000000000001 > > [ 3.010671] RDX: 0000000000000000 RSI: ffffffffb268dd21 RDI: ffffffffb269ab13 > > [ 3.010673] RBP: 0000000000000001 R08: ffffffffffc300d5 R09: 000000000002be80 > > [ 3.010674] R10: 000003625b53183a R11: ffffa012b802b7a4 R12: ffffffffb2aa9e80 > > [ 3.010675] R13: ffffffffb2aa9e00 R14: 0000000000000001 R15: 0000000000000000 > > [ 3.010677] FS: 0000000000000000(0000) GS:ffffa012b8000000(0000) knlGS:0000000000000000 > > [ 3.010678] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 3.010680] CR2: ffffa012f81ff000 CR3: 0000000c99612001 CR4: 00000000003706f0 > > [ 3.010681] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > [ 3.010682] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > [ 3.010683] Call Trace: > > [ 3.010685] > > [ 3.010688] cpuidle_enter_state+0xb7/0x4b0 > > [ 3.010694] cpuidle_enter+0x29/0x40 > > [ 3.010697] do_idle+0x1d4/0x210 > > [ 3.010702] cpu_startup_entry+0x19/0x20 > > [ 3.010704] rest_init+0x117/0x1a0 > > [ 3.010708] arch_call_rest_init+0xa/0x10 > > [ 3.010711] start_kernel+0x6d8/0x6ff > > [ 3.010716] secondary_startup_64_no_verify+0xce/0xdb > > [ 3.010728] > > [ 3.010729] irq event stamp: 44179 > > [ 3.010730] hardirqs last enabled at (44179): [] asm_sysvec_apic_timer_interrupt+0x1b/0x20 > > [ 3.010734] hardirqs last disabled at (44177): [] __do_softirq+0x3f0/0x498 > > [ 3.010736] softirqs last enabled at (44178): [] __do_softirq+0x332/0x498 > > [ 3.010738] softirqs last disabled at (44171): [] irq_exit_rcu+0xab/0xf0 > > [ 3.010741] ---[ end trace 0000000000000000 ]--- > > Would you be willing to try another shot in the dark, but untested > this time? I freely admit that this is getting strange. > > Thanx, Paul > > ------------------------------------------------------------------------ > > diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c > index e374c0c923dae..279f557bf60bb 100644 > --- a/kernel/sched/clock.c > +++ b/kernel/sched/clock.c > @@ -394,7 +394,7 @@ notrace void sched_clock_tick(void) > if (!static_branch_likely(&sched_clock_running)) > return; > > - lockdep_assert_irqs_disabled(); > + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled()); > > scd = this_scd(); > __scd_stamp(scd); _______________________________________________ linux-riscv mailing list linux-riscv@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-riscv 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 mail.librecores.org (lists.librecores.org [88.198.125.70]) by smtp.lore.kernel.org (Postfix) with ESMTP id D028BC25B08 for ; Sun, 31 Jul 2022 22:07:42 +0000 (UTC) Received: from [172.31.1.100] (localhost.localdomain [127.0.0.1]) by mail.librecores.org (Postfix) with ESMTP id 512BB240DA; Mon, 1 Aug 2022 00:07:42 +0200 (CEST) Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by mail.librecores.org (Postfix) with ESMTPS id 93133248E4 for ; Fri, 29 Jul 2022 17:28:15 +0200 (CEST) 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 0B522B82844; Fri, 29 Jul 2022 15:28:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1F1EC433D6; Fri, 29 Jul 2022 15:28:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659108493; bh=+Eu1+NpdMQSxhSpBOHg1xq9IY5RE5+jGBaKhcxBU/fw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=SYC3Dsw++Jo9/onL7ZbEg1e34NjAkGJ0/LEyzxxtRyARi5tsRhnhMCBXpA48hlrbx /ygCpipyirN70BTWI+O7BPw3KEXhwiaeJ1toIS9f4x8NNUrtDb0g9IXD0fU2Bmoo6M w/YCbZ5sds6/EqIKdGN13GNgPIYzv0deYvecUifHVmZHvmvFFPvpCRqJ8szO8EVscM zHVucD9HNGWsnSLNuXErgrHHYht/KZ+I5xQvurQSs2gAeRSzLQTzOZZkq+fQyiif2B dBwd0T3KOaUJi1JScRgdDFB1nTqlfa6EEzGGbx1ADBkWPp5B2oyL/vemt0EQW8/A3l tsRJX93dX43kQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 77B5C5C033E; Fri, 29 Jul 2022 08:28:13 -0700 (PDT) Date: Fri, 29 Jul 2022 08:28:13 -0700 From: "Paul E. McKenney" To: Michel Lespinasse Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE Message-ID: <20220729152813.GA3579395@paulmck-ThinkPad-P17-Gen-1> References: <20220608142723.103523089@infradead.org> <20220608144516.172460444@infradead.org> <20220725194306.GA14746@lespinasse.org> <20220728172053.GA3607379@paulmck-ThinkPad-P17-Gen-1> <20220729102458.GA1695@lespinasse.org> <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> X-Mailman-Approved-At: Mon, 01 Aug 2022 00:07:35 +0200 X-BeenThere: openrisc@lists.librecores.org X-Mailman-Version: 2.1.26 Precedence: list List-Id: Discussion around the OpenRISC processor List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: paulmck@kernel.org Cc: juri.lelli@redhat.com, rafael@kernel.org, benh@kernel.crashing.org, linus.walleij@linaro.org, bsegall@google.com, guoren@kernel.org, pavel@ucw.cz, agordeev@linux.ibm.com, srivatsa@csail.mit.edu, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, mpe@ellerman.id.au, chenhuacai@kernel.org, linux-acpi@vger.kernel.org, agross@kernel.org, linux-imx@nxp.com, catalin.marinas@arm.com, xen-devel@lists.xenproject.org, mattst88@gmail.com, borntraeger@linux.ibm.com, mturquette@baylibre.com, sammy@sammy.net, pmladek@suse.com, linux-pm@vger.kernel.org, jiangshanlai@gmail.com, Sascha Hauer , linux-um@lists.infradead.org, acme@kernel.org, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.com, rth@twiddle.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, senozhatsky@chromium.org, svens@linux.ibm.com, jolsa@kernel.org, paulus@samba.org, mark.rutland@arm.com, linux-ia64@vger.kernel.org, dave.hansen@linux.intel.com, virtualization@lists.linux-foundation.org, James.Bottomley@HansenPartnership.com, jcmvbkbc@gmail.com, thierry.reding@gmail.com, kernel@xen0n.name, quic_neeraju@quicinc.com, linux-s390@vger.kernel.org, vschneid@redhat.com, john.ogness@linutronix.de, ysato@users.sourceforge.jp, linux-sh@vger.kernel.org, festevam@gmail.com, deller@gmx.de, daniel.lezcano@linaro.org, jonathanh@nvidia.com, mathieu.desnoyers@efficios.com, frederic@kernel.org, lenb@kernel.org, linux-xtensa@linux-xtensa.org, kernel@pengutronix.de, gor@linux.ibm.com, linux-arm-msm@vger.kernel.org, linux-alpha@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-arm-kernel@lists.infradead.org, chris@zankel.net, sboyd@kernel.org, rh0@fb.com, dinguyen@kernel.org, bristot@redhat.com, alexander.shishkin@linux.intel.com, lpieralisi@kernel.org, linux@rasmusvillemoes.dk, joel@joelfernandes.org, will@kernel.org, boris.ostrovsky@oracle.com, josh@joshtriplett.org, khilman@kernel.org, linux-csky@vger.kernel.org, tony@atomide.com, linux-snps-arc@lists.infradead.org, mgorman@suse.de, jacob.jun.pan@linux.intel.com, yury.norov@gmail.com, ulli.kroll@googlemail.com, vgupta@kernel.org, linux-clk@vger.kernel.org, monstr@monstr.eu, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, Peter Zijlstra , amakhalov@vmware.com, bjorn.andersson@linaro.org, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, anton.ivanov@cambridgegreys.com, jonas@southpole.se, Arnd Bergmann , richard@nod.at, x86@kernel.org, linux@armlinux.org.uk, mingo@redhat.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, openrisc@lists.librecores.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kernel.org, jgross@suse.com, pv-drivers@vmware.com, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@brainfault.org, ink@jurassic.park.msu.ru, johannes@sipsolutions.net, linuxppc-dev@lists.ozlabs.org Errors-To: openrisc-bounces@lists.librecores.org Sender: "OpenRISC" Or better yet, try the patch that Rafael proposed. ;-) Thanx, Paul On Fri, Jul 29, 2022 at 08:26:22AM -0700, Paul E. McKenney wrote: > On Fri, Jul 29, 2022 at 03:24:58AM -0700, Michel Lespinasse wrote: > > On Thu, Jul 28, 2022 at 10:20:53AM -0700, Paul E. McKenney wrote: > > > On Mon, Jul 25, 2022 at 12:43:06PM -0700, Michel Lespinasse wrote: > > > > On Wed, Jun 08, 2022 at 04:27:27PM +0200, Peter Zijlstra wrote: > > > > > Commit c227233ad64c ("intel_idle: enable interrupts before C1 on > > > > > Xeons") wrecked intel_idle in two ways: > > > > > > > > > > - must not have tracing in idle functions > > > > > - must return with IRQs disabled > > > > > > > > > > Additionally, it added a branch for no good reason. > > > > > > > > > > Fixes: c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons") > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > > > > > > After this change was introduced, I am seeing "WARNING: suspicious RCU > > > > usage" when booting a kernel with debug options compiled in. Please > > > > see the attached dmesg output. The issue starts with commit 32d4fd5751ea > > > > and is still present in v5.19-rc8. > > > > > > > > I'm not sure, is this too late to fix or revert in v5.19 final ? > > > > > > I finally got a chance to take a quick look at this. > > > > > > The rcu_eqs_exit() function is making a lockdep complaint about > > > being invoked with interrupts enabled. This function is called from > > > rcu_idle_exit(), which is an expected code path from cpuidle_enter_state() > > > via its call to rcu_idle_exit(). Except that rcu_idle_exit() disables > > > interrupts before invoking rcu_eqs_exit(). > > > > > > The only other call to rcu_idle_exit() does not disable interrupts, > > > but it is via rcu_user_exit(), which would be a very odd choice for > > > cpuidle_enter_state(). > > > > > > It seems unlikely, but it might be that it is the use of local_irq_save() > > > instead of raw_local_irq_save() within rcu_idle_exit() that is causing > > > the trouble. If this is the case, then the commit shown below would > > > help. Note that this commit removes the warning from lockdep, so it > > > is necessary to build the kernel with CONFIG_RCU_EQS_DEBUG=y to enable > > > equivalent debugging. > > > > > > Could you please try your test with the -rce commit shown below applied? > > > > Thanks for looking into it. > > And thank you for trying this shot in the dark! > > > After checking out Peter's commit 32d4fd5751ea, > > cherry picking your commit ed4ae5eff4b3, > > and setting CONFIG_RCU_EQS_DEBUG=y in addition of my usual debug config, > > I am now seeing this a few seconds into the boot: > > > > [ 3.010650] ------------[ cut here ]------------ > > [ 3.010651] WARNING: CPU: 0 PID: 0 at kernel/sched/clock.c:397 sched_clock_tick+0x27/0x60 > > And this is again a complaint about interrupts not being disabled. > > But it does appear that the problem was the lockdep complaint, and > eliminating that did take care of part of the problem. But lockdep > remained enabled, and you therefore hit the next complaint. > > > [ 3.010657] Modules linked in: > > [ 3.010660] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc1-test-00005-g1be22fea0611 #1 > > [ 3.010662] Hardware name: LENOVO 30BFS44D00/1036, BIOS S03KT51A 01/17/2022 > > [ 3.010663] RIP: 0010:sched_clock_tick+0x27/0x60 > > The most straightforward way to get to sched_clock_tick() from > cpuidle_enter_state() is via the call to sched_clock_idle_wakeup_event(). > > Except that it disables interrupts before invoking sched_clock_tick(). > > > [ 3.010665] Code: 1f 40 00 53 eb 02 5b c3 66 90 8b 05 2f c3 40 01 85 c0 74 18 65 8b 05 60 88 8f 4e 85 c0 75 0d 65 8b 05 a9 85 8f 4e 85 c0 74 02 <0f> 0b e8 e2 6c 89 00 48 c7 c3 40 d5 02 00 > > 89 c0 48 03 1c c5 c0 98 > > [ 3.010667] RSP: 0000:ffffffffb2803e28 EFLAGS: 00010002 > > [ 3.010670] RAX: 0000000000000001 RBX: ffffc8ce7fa07060 RCX: 0000000000000001 > > [ 3.010671] RDX: 0000000000000000 RSI: ffffffffb268dd21 RDI: ffffffffb269ab13 > > [ 3.010673] RBP: 0000000000000001 R08: ffffffffffc300d5 R09: 000000000002be80 > > [ 3.010674] R10: 000003625b53183a R11: ffffa012b802b7a4 R12: ffffffffb2aa9e80 > > [ 3.010675] R13: ffffffffb2aa9e00 R14: 0000000000000001 R15: 0000000000000000 > > [ 3.010677] FS: 0000000000000000(0000) GS:ffffa012b8000000(0000) knlGS:0000000000000000 > > [ 3.010678] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 3.010680] CR2: ffffa012f81ff000 CR3: 0000000c99612001 CR4: 00000000003706f0 > > [ 3.010681] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > [ 3.010682] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > [ 3.010683] Call Trace: > > [ 3.010685] > > [ 3.010688] cpuidle_enter_state+0xb7/0x4b0 > > [ 3.010694] cpuidle_enter+0x29/0x40 > > [ 3.010697] do_idle+0x1d4/0x210 > > [ 3.010702] cpu_startup_entry+0x19/0x20 > > [ 3.010704] rest_init+0x117/0x1a0 > > [ 3.010708] arch_call_rest_init+0xa/0x10 > > [ 3.010711] start_kernel+0x6d8/0x6ff > > [ 3.010716] secondary_startup_64_no_verify+0xce/0xdb > > [ 3.010728] > > [ 3.010729] irq event stamp: 44179 > > [ 3.010730] hardirqs last enabled at (44179): [] asm_sysvec_apic_timer_interrupt+0x1b/0x20 > > [ 3.010734] hardirqs last disabled at (44177): [] __do_softirq+0x3f0/0x498 > > [ 3.010736] softirqs last enabled at (44178): [] __do_softirq+0x332/0x498 > > [ 3.010738] softirqs last disabled at (44171): [] irq_exit_rcu+0xab/0xf0 > > [ 3.010741] ---[ end trace 0000000000000000 ]--- > > Would you be willing to try another shot in the dark, but untested > this time? I freely admit that this is getting strange. > > Thanx, Paul > > ------------------------------------------------------------------------ > > diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c > index e374c0c923dae..279f557bf60bb 100644 > --- a/kernel/sched/clock.c > +++ b/kernel/sched/clock.c > @@ -394,7 +394,7 @@ notrace void sched_clock_tick(void) > if (!static_branch_likely(&sched_clock_running)) > return; > > - lockdep_assert_irqs_disabled(); > + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled()); > > scd = this_scd(); > __scd_stamp(scd); 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 92922C19F2A for ; Fri, 29 Jul 2022 16:32:13 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4LvY2N16z7z3cdN for ; Sat, 30 Jul 2022 02:32:12 +1000 (AEST) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=SYC3Dsw+; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=kernel.org (client-ip=145.40.68.75; helo=ams.source.kernel.org; envelope-from=srs0=719g=yc=paulmck-thinkpad-p17-gen-1.home=paulmck@kernel.org; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=kernel.org header.i=@kernel.org header.a=rsa-sha256 header.s=k20201202 header.b=SYC3Dsw+; dkim-atps=neutral Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4LvWcg3xlQz2xGm for ; Sat, 30 Jul 2022 01:28:19 +1000 (AEST) 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 0B522B82844; Fri, 29 Jul 2022 15:28:15 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1F1EC433D6; Fri, 29 Jul 2022 15:28:13 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659108493; bh=+Eu1+NpdMQSxhSpBOHg1xq9IY5RE5+jGBaKhcxBU/fw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=SYC3Dsw++Jo9/onL7ZbEg1e34NjAkGJ0/LEyzxxtRyARi5tsRhnhMCBXpA48hlrbx /ygCpipyirN70BTWI+O7BPw3KEXhwiaeJ1toIS9f4x8NNUrtDb0g9IXD0fU2Bmoo6M w/YCbZ5sds6/EqIKdGN13GNgPIYzv0deYvecUifHVmZHvmvFFPvpCRqJ8szO8EVscM zHVucD9HNGWsnSLNuXErgrHHYht/KZ+I5xQvurQSs2gAeRSzLQTzOZZkq+fQyiif2B dBwd0T3KOaUJi1JScRgdDFB1nTqlfa6EEzGGbx1ADBkWPp5B2oyL/vemt0EQW8/A3l tsRJX93dX43kQ== Received: by paulmck-ThinkPad-P17-Gen-1.home (Postfix, from userid 1000) id 77B5C5C033E; Fri, 29 Jul 2022 08:28:13 -0700 (PDT) Date: Fri, 29 Jul 2022 08:28:13 -0700 From: "Paul E. McKenney" To: Michel Lespinasse Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE Message-ID: <20220729152813.GA3579395@paulmck-ThinkPad-P17-Gen-1> References: <20220608142723.103523089@infradead.org> <20220608144516.172460444@infradead.org> <20220725194306.GA14746@lespinasse.org> <20220728172053.GA3607379@paulmck-ThinkPad-P17-Gen-1> <20220729102458.GA1695@lespinasse.org> <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> X-Mailman-Approved-At: Sat, 30 Jul 2022 02:30:06 +1000 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Reply-To: paulmck@kernel.org Cc: juri.lelli@redhat.com, rafael@kernel.org, linus.walleij@linaro.org, bsegall@google.com, guoren@kernel.org, pavel@ucw.cz, agordeev@linux.ibm.com, srivatsa@csail.mit.edu, linux-arch@vger.kernel.org, vincent.guittot@linaro.org, chenhuacai@kernel.org, linux-acpi@vger.kernel.org, agross@kernel.org, geert@linux-m68k.org, linux-imx@nxp.com, catalin.marinas@arm.com, xen-devel@lists.xenproject.org, mattst88@gmail.com, borntraeger@linux.ibm.com, mturquette@baylibre.com, sammy@sammy.net, pmladek@suse.com, linux-pm@vger.kernel.org, jiangshanlai@gmail.com, Sascha Hauer , linux-um@lists.infradead.org, acme@kernel.org, tglx@linutronix.de, linux-omap@vger.kernel.org, dietmar.eggemann@arm.com, rth@twiddle.net, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org, senozhatsky@chromium.org, svens@linux.ibm.com, jolsa@kernel.org, paulus@samba.org, mark.rutland@arm.com, linux-ia64@vger.kernel.org, dave.hansen@linux.intel.com, virtualizatio n@lists.linux-foundation.org, James.Bottomley@HansenPartnership.com, jcmvbkbc@gmail.com, thierry.reding@gmail.com, kernel@xen0n.name, quic_neeraju@quicinc.com, linux-s390@vger.kernel.org, vschneid@redhat.com, john.ogness@linutronix.de, ysato@users.sourceforge.jp, linux-sh@vger.kernel.org, festevam@gmail.com, deller@gmx.de, daniel.lezcano@linaro.org, jonathanh@nvidia.com, mathieu.desnoyers@efficios.com, frederic@kernel.org, lenb@kernel.org, linux-xtensa@linux-xtensa.org, kernel@pengutronix.de, gor@linux.ibm.com, linux-arm-msm@vger.kernel.org, linux-alpha@vger.kernel.org, linux-m68k@lists.linux-m68k.org, shorne@gmail.com, linux-arm-kernel@lists.infradead.org, chris@zankel.net, sboyd@kernel.org, rh0@fb.com, dinguyen@kernel.org, bristot@redhat.com, alexander.shishkin@linux.intel.com, lpieralisi@kernel.org, linux@rasmusvillemoes.dk, joel@joelfernandes.org, will@kernel.org, boris.ostrovsky@oracle.com, josh@joshtriplett.org, khilman@kernel.org, linux-csky@vger.kernel.org, tony@atomide.com, linux-snps-arc@lists.infradead.org, mgorman@suse.de, jacob.jun.pan@linux.intel.com, yury.norov@gmail.com, ulli.kroll@googlemail.com, vgupta@kernel.org, linux-clk@vger.kernel.org, monstr@monstr.eu, rostedt@goodmis.org, rcu@vger.kernel.org, bp@alien8.de, bcain@quicinc.com, tsbogend@alpha.franken.de, linux-parisc@vger.kernel.org, sudeep.holla@arm.com, shawnguo@kernel.org, davem@davemloft.net, dalias@libc.org, Peter Zijlstra , amakhalov@vmware.com, bjorn.andersson@linaro.org, hpa@zytor.com, sparclinux@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-riscv@lists.infradead.org, anton.ivanov@cambridgegreys.com, jonas@southpole.se, Arnd Bergmann , richard@nod.at, x86@kernel.org, linux@armlinux.org.uk, mingo@redhat.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, stefan.kristiansson@saunalahti.fi, openrisc@lists.librecores.org, paul.walmsley@sifive.com, linux-tegra@vger.kernel.org, namhyung@kernel.org, andriy.shevchenko@linux.intel.com, jpoimboe@kerne l.org, jgross@suse.com, pv-drivers@vmware.com, linux-mips@vger.kernel.org, palmer@dabbelt.com, anup@brainfault.org, ink@jurassic.park.msu.ru, johannes@sipsolutions.net, linuxppc-dev@lists.ozlabs.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Or better yet, try the patch that Rafael proposed. ;-) Thanx, Paul On Fri, Jul 29, 2022 at 08:26:22AM -0700, Paul E. McKenney wrote: > On Fri, Jul 29, 2022 at 03:24:58AM -0700, Michel Lespinasse wrote: > > On Thu, Jul 28, 2022 at 10:20:53AM -0700, Paul E. McKenney wrote: > > > On Mon, Jul 25, 2022 at 12:43:06PM -0700, Michel Lespinasse wrote: > > > > On Wed, Jun 08, 2022 at 04:27:27PM +0200, Peter Zijlstra wrote: > > > > > Commit c227233ad64c ("intel_idle: enable interrupts before C1 on > > > > > Xeons") wrecked intel_idle in two ways: > > > > > > > > > > - must not have tracing in idle functions > > > > > - must return with IRQs disabled > > > > > > > > > > Additionally, it added a branch for no good reason. > > > > > > > > > > Fixes: c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons") > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > > > > > > After this change was introduced, I am seeing "WARNING: suspicious RCU > > > > usage" when booting a kernel with debug options compiled in. Please > > > > see the attached dmesg output. The issue starts with commit 32d4fd5751ea > > > > and is still present in v5.19-rc8. > > > > > > > > I'm not sure, is this too late to fix or revert in v5.19 final ? > > > > > > I finally got a chance to take a quick look at this. > > > > > > The rcu_eqs_exit() function is making a lockdep complaint about > > > being invoked with interrupts enabled. This function is called from > > > rcu_idle_exit(), which is an expected code path from cpuidle_enter_state() > > > via its call to rcu_idle_exit(). Except that rcu_idle_exit() disables > > > interrupts before invoking rcu_eqs_exit(). > > > > > > The only other call to rcu_idle_exit() does not disable interrupts, > > > but it is via rcu_user_exit(), which would be a very odd choice for > > > cpuidle_enter_state(). > > > > > > It seems unlikely, but it might be that it is the use of local_irq_save() > > > instead of raw_local_irq_save() within rcu_idle_exit() that is causing > > > the trouble. If this is the case, then the commit shown below would > > > help. Note that this commit removes the warning from lockdep, so it > > > is necessary to build the kernel with CONFIG_RCU_EQS_DEBUG=y to enable > > > equivalent debugging. > > > > > > Could you please try your test with the -rce commit shown below applied? > > > > Thanks for looking into it. > > And thank you for trying this shot in the dark! > > > After checking out Peter's commit 32d4fd5751ea, > > cherry picking your commit ed4ae5eff4b3, > > and setting CONFIG_RCU_EQS_DEBUG=y in addition of my usual debug config, > > I am now seeing this a few seconds into the boot: > > > > [ 3.010650] ------------[ cut here ]------------ > > [ 3.010651] WARNING: CPU: 0 PID: 0 at kernel/sched/clock.c:397 sched_clock_tick+0x27/0x60 > > And this is again a complaint about interrupts not being disabled. > > But it does appear that the problem was the lockdep complaint, and > eliminating that did take care of part of the problem. But lockdep > remained enabled, and you therefore hit the next complaint. > > > [ 3.010657] Modules linked in: > > [ 3.010660] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc1-test-00005-g1be22fea0611 #1 > > [ 3.010662] Hardware name: LENOVO 30BFS44D00/1036, BIOS S03KT51A 01/17/2022 > > [ 3.010663] RIP: 0010:sched_clock_tick+0x27/0x60 > > The most straightforward way to get to sched_clock_tick() from > cpuidle_enter_state() is via the call to sched_clock_idle_wakeup_event(). > > Except that it disables interrupts before invoking sched_clock_tick(). > > > [ 3.010665] Code: 1f 40 00 53 eb 02 5b c3 66 90 8b 05 2f c3 40 01 85 c0 74 18 65 8b 05 60 88 8f 4e 85 c0 75 0d 65 8b 05 a9 85 8f 4e 85 c0 74 02 <0f> 0b e8 e2 6c 89 00 48 c7 c3 40 d5 02 00 > > 89 c0 48 03 1c c5 c0 98 > > [ 3.010667] RSP: 0000:ffffffffb2803e28 EFLAGS: 00010002 > > [ 3.010670] RAX: 0000000000000001 RBX: ffffc8ce7fa07060 RCX: 0000000000000001 > > [ 3.010671] RDX: 0000000000000000 RSI: ffffffffb268dd21 RDI: ffffffffb269ab13 > > [ 3.010673] RBP: 0000000000000001 R08: ffffffffffc300d5 R09: 000000000002be80 > > [ 3.010674] R10: 000003625b53183a R11: ffffa012b802b7a4 R12: ffffffffb2aa9e80 > > [ 3.010675] R13: ffffffffb2aa9e00 R14: 0000000000000001 R15: 0000000000000000 > > [ 3.010677] FS: 0000000000000000(0000) GS:ffffa012b8000000(0000) knlGS:0000000000000000 > > [ 3.010678] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 3.010680] CR2: ffffa012f81ff000 CR3: 0000000c99612001 CR4: 00000000003706f0 > > [ 3.010681] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > [ 3.010682] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > [ 3.010683] Call Trace: > > [ 3.010685] > > [ 3.010688] cpuidle_enter_state+0xb7/0x4b0 > > [ 3.010694] cpuidle_enter+0x29/0x40 > > [ 3.010697] do_idle+0x1d4/0x210 > > [ 3.010702] cpu_startup_entry+0x19/0x20 > > [ 3.010704] rest_init+0x117/0x1a0 > > [ 3.010708] arch_call_rest_init+0xa/0x10 > > [ 3.010711] start_kernel+0x6d8/0x6ff > > [ 3.010716] secondary_startup_64_no_verify+0xce/0xdb > > [ 3.010728] > > [ 3.010729] irq event stamp: 44179 > > [ 3.010730] hardirqs last enabled at (44179): [] asm_sysvec_apic_timer_interrupt+0x1b/0x20 > > [ 3.010734] hardirqs last disabled at (44177): [] __do_softirq+0x3f0/0x498 > > [ 3.010736] softirqs last enabled at (44178): [] __do_softirq+0x332/0x498 > > [ 3.010738] softirqs last disabled at (44171): [] irq_exit_rcu+0xab/0xf0 > > [ 3.010741] ---[ end trace 0000000000000000 ]--- > > Would you be willing to try another shot in the dark, but untested > this time? I freely admit that this is getting strange. > > Thanx, Paul > > ------------------------------------------------------------------------ > > diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c > index e374c0c923dae..279f557bf60bb 100644 > --- a/kernel/sched/clock.c > +++ b/kernel/sched/clock.c > @@ -394,7 +394,7 @@ notrace void sched_clock_tick(void) > if (!static_branch_likely(&sched_clock_running)) > return; > > - lockdep_assert_irqs_disabled(); > + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled()); > > scd = this_scd(); > __scd_stamp(scd); From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Date: Fri, 29 Jul 2022 15:28:13 +0000 Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE Message-Id: <20220729152813.GA3579395@paulmck-ThinkPad-P17-Gen-1> List-Id: References: <20220608142723.103523089@infradead.org> <20220608144516.172460444@infradead.org> <20220725194306.GA14746@lespinasse.org> <20220728172053.GA3607379@paulmck-ThinkPad-P17-Gen-1> <20220729102458.GA1695@lespinasse.org> <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> In-Reply-To: <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michel Lespinasse Cc: Peter Zijlstra , rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sifive.com, palmer@dabbelt.com, aou@eecs.berkeley.edu, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, ysato@users.sourceforge.jp, dalias@libc.org, davem@davemloft.net, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@linutronix.de, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, acme@kernel.org, mark.rutland@arm.com, alexander.shishkin@linux.intel.com, jolsa@kernel.org, namhyung@kernel.org, jgross@suse.com, srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, boris.ostrovsky@oracle.com, chris@zankel.net, jcmvbkbc@gmail.com, rafael@kernel.org, lenb@kernel.org, pavel@ucw.cz, gregkh@linuxfoundation.org, mturquette@baylibre.com, sboyd@kernel.org, daniel.lezcano@linaro.org, lpieralisi@kernel.org, sudeep.holla@arm.com, agross@kernel.org, bjorn.andersson@linaro.org, anup@brainfault.org, thierry.reding@gmail.com, jonathanh@nvidia.com, jacob.jun.pan@linux.intel.com, Arnd Bergmann , yury.norov@gmail.com, andriy.shevchenko@linux.intel.com, linux@rasmusvillemoes.dk, rostedt@goodmis.org, pmladek@suse.com, senozhatsky@chromium.org, john.ogness@linutronix.de, frederic@kernel.org, quic_neeraju@quicinc.com, josh@joshtriplett.org, mathieu.desnoyers@efficios.com, jiangshanlai@gmail.com, joel@joelfernandes.org, juri.lelli@redhat.com, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, bsegall@google.com, mgorman@suse.de, bristot@redhat.com, vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, linux-snps-arc@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-omap@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-mips@vger.kernel.org, openrisc@lists.librecores.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-riscv@lists.infradead.org, linux-s390@vger.kernel.org, linux-sh@vger.kernel.org, sparclinux@vger.kernel.org, linux-um@lists.infradead.org, linux-perf-users@vger.kernel.org, virtualization@lists.linux-foundation.org, xen-devel@lists.xenproject.org, linux-xtensa@linux-xtensa.org, linux-acpi@vger.kernel.org, linux-pm@vger.kernel.org, linux-clk@vger.kernel.org, linux-arm-msm@vger.kernel.org, linux-tegra@vger.kernel.org, linux-arch@vger.kernel.org, rcu@vger.kernel.org, rh0@fb.com Or better yet, try the patch that Rafael proposed. ;-) Thanx, Paul On Fri, Jul 29, 2022 at 08:26:22AM -0700, Paul E. McKenney wrote: > On Fri, Jul 29, 2022 at 03:24:58AM -0700, Michel Lespinasse wrote: > > On Thu, Jul 28, 2022 at 10:20:53AM -0700, Paul E. McKenney wrote: > > > On Mon, Jul 25, 2022 at 12:43:06PM -0700, Michel Lespinasse wrote: > > > > On Wed, Jun 08, 2022 at 04:27:27PM +0200, Peter Zijlstra wrote: > > > > > Commit c227233ad64c ("intel_idle: enable interrupts before C1 on > > > > > Xeons") wrecked intel_idle in two ways: > > > > > > > > > > - must not have tracing in idle functions > > > > > - must return with IRQs disabled > > > > > > > > > > Additionally, it added a branch for no good reason. > > > > > > > > > > Fixes: c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons") > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > > > > > > After this change was introduced, I am seeing "WARNING: suspicious RCU > > > > usage" when booting a kernel with debug options compiled in. Please > > > > see the attached dmesg output. The issue starts with commit 32d4fd5751ea > > > > and is still present in v5.19-rc8. > > > > > > > > I'm not sure, is this too late to fix or revert in v5.19 final ? > > > > > > I finally got a chance to take a quick look at this. > > > > > > The rcu_eqs_exit() function is making a lockdep complaint about > > > being invoked with interrupts enabled. This function is called from > > > rcu_idle_exit(), which is an expected code path from cpuidle_enter_state() > > > via its call to rcu_idle_exit(). Except that rcu_idle_exit() disables > > > interrupts before invoking rcu_eqs_exit(). > > > > > > The only other call to rcu_idle_exit() does not disable interrupts, > > > but it is via rcu_user_exit(), which would be a very odd choice for > > > cpuidle_enter_state(). > > > > > > It seems unlikely, but it might be that it is the use of local_irq_save() > > > instead of raw_local_irq_save() within rcu_idle_exit() that is causing > > > the trouble. If this is the case, then the commit shown below would > > > help. Note that this commit removes the warning from lockdep, so it > > > is necessary to build the kernel with CONFIG_RCU_EQS_DEBUG=y to enable > > > equivalent debugging. > > > > > > Could you please try your test with the -rce commit shown below applied? > > > > Thanks for looking into it. > > And thank you for trying this shot in the dark! > > > After checking out Peter's commit 32d4fd5751ea, > > cherry picking your commit ed4ae5eff4b3, > > and setting CONFIG_RCU_EQS_DEBUG=y in addition of my usual debug config, > > I am now seeing this a few seconds into the boot: > > > > [ 3.010650] ------------[ cut here ]------------ > > [ 3.010651] WARNING: CPU: 0 PID: 0 at kernel/sched/clock.c:397 sched_clock_tick+0x27/0x60 > > And this is again a complaint about interrupts not being disabled. > > But it does appear that the problem was the lockdep complaint, and > eliminating that did take care of part of the problem. But lockdep > remained enabled, and you therefore hit the next complaint. > > > [ 3.010657] Modules linked in: > > [ 3.010660] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc1-test-00005-g1be22fea0611 #1 > > [ 3.010662] Hardware name: LENOVO 30BFS44D00/1036, BIOS S03KT51A 01/17/2022 > > [ 3.010663] RIP: 0010:sched_clock_tick+0x27/0x60 > > The most straightforward way to get to sched_clock_tick() from > cpuidle_enter_state() is via the call to sched_clock_idle_wakeup_event(). > > Except that it disables interrupts before invoking sched_clock_tick(). > > > [ 3.010665] Code: 1f 40 00 53 eb 02 5b c3 66 90 8b 05 2f c3 40 01 85 c0 74 18 65 8b 05 60 88 8f 4e 85 c0 75 0d 65 8b 05 a9 85 8f 4e 85 c0 74 02 <0f> 0b e8 e2 6c 89 00 48 c7 c3 40 d5 02 00 > > 89 c0 48 03 1c c5 c0 98 > > [ 3.010667] RSP: 0000:ffffffffb2803e28 EFLAGS: 00010002 > > [ 3.010670] RAX: 0000000000000001 RBX: ffffc8ce7fa07060 RCX: 0000000000000001 > > [ 3.010671] RDX: 0000000000000000 RSI: ffffffffb268dd21 RDI: ffffffffb269ab13 > > [ 3.010673] RBP: 0000000000000001 R08: ffffffffffc300d5 R09: 000000000002be80 > > [ 3.010674] R10: 000003625b53183a R11: ffffa012b802b7a4 R12: ffffffffb2aa9e80 > > [ 3.010675] R13: ffffffffb2aa9e00 R14: 0000000000000001 R15: 0000000000000000 > > [ 3.010677] FS: 0000000000000000(0000) GS:ffffa012b8000000(0000) knlGS:0000000000000000 > > [ 3.010678] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 3.010680] CR2: ffffa012f81ff000 CR3: 0000000c99612001 CR4: 00000000003706f0 > > [ 3.010681] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > [ 3.010682] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > [ 3.010683] Call Trace: > > [ 3.010685] > > [ 3.010688] cpuidle_enter_state+0xb7/0x4b0 > > [ 3.010694] cpuidle_enter+0x29/0x40 > > [ 3.010697] do_idle+0x1d4/0x210 > > [ 3.010702] cpu_startup_entry+0x19/0x20 > > [ 3.010704] rest_init+0x117/0x1a0 > > [ 3.010708] arch_call_rest_init+0xa/0x10 > > [ 3.010711] start_kernel+0x6d8/0x6ff > > [ 3.010716] secondary_startup_64_no_verify+0xce/0xdb > > [ 3.010728] > > [ 3.010729] irq event stamp: 44179 > > [ 3.010730] hardirqs last enabled at (44179): [] asm_sysvec_apic_timer_interrupt+0x1b/0x20 > > [ 3.010734] hardirqs last disabled at (44177): [] __do_softirq+0x3f0/0x498 > > [ 3.010736] softirqs last enabled at (44178): [] __do_softirq+0x332/0x498 > > [ 3.010738] softirqs last disabled at (44171): [] irq_exit_rcu+0xab/0xf0 > > [ 3.010741] ---[ end trace 0000000000000000 ]--- > > Would you be willing to try another shot in the dark, but untested > this time? I freely admit that this is getting strange. > > Thanx, Paul > > ------------------------------------------------------------------------ > > diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c > index e374c0c923dae..279f557bf60bb 100644 > --- a/kernel/sched/clock.c > +++ b/kernel/sched/clock.c > @@ -394,7 +394,7 @@ notrace void sched_clock_tick(void) > if (!static_branch_likely(&sched_clock_running)) > return; > > - lockdep_assert_irqs_disabled(); > + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled()); > > scd = this_scd(); > __scd_stamp(scd); From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Paul E. McKenney" Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE Date: Fri, 29 Jul 2022 08:28:13 -0700 Message-ID: <20220729152813.GA3579395@paulmck-ThinkPad-P17-Gen-1> References: <20220608142723.103523089@infradead.org> <20220608144516.172460444@infradead.org> <20220725194306.GA14746@lespinasse.org> <20220728172053.GA3607379@paulmck-ThinkPad-P17-Gen-1> <20220729102458.GA1695@lespinasse.org> <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> Reply-To: paulmck@kernel.org Mime-Version: 1.0 Return-path: DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1659108493; bh=+Eu1+NpdMQSxhSpBOHg1xq9IY5RE5+jGBaKhcxBU/fw=; h=Date:From:To:Cc:Subject:Reply-To:References:In-Reply-To:From; b=SYC3Dsw++Jo9/onL7ZbEg1e34NjAkGJ0/LEyzxxtRyARi5tsRhnhMCBXpA48hlrbx /ygCpipyirN70BTWI+O7BPw3KEXhwiaeJ1toIS9f4x8NNUrtDb0g9IXD0fU2Bmoo6M w/YCbZ5sds6/EqIKdGN13GNgPIYzv0deYvecUifHVmZHvmvFFPvpCRqJ8szO8EVscM zHVucD9HNGWsnSLNuXErgrHHYht/KZ+I5xQvurQSs2gAeRSzLQTzOZZkq+fQyiif2B dBwd0T3KOaUJi1JScRgdDFB1nTqlfa6EEzGGbx1ADBkWPp5B2oyL/vemt0EQW8/A3l tsRJX93dX43kQ== Content-Disposition: inline In-Reply-To: <20220729152622.GM2860372@paulmck-ThinkPad-P17-Gen-1> List-ID: Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Michel Lespinasse Cc: Peter Zijlstra , rth@twiddle.net, ink@jurassic.park.msu.ru, mattst88@gmail.com, vgupta@kernel.org, linux@armlinux.org.uk, ulli.kroll@googlemail.com, linus.walleij@linaro.org, shawnguo@kernel.org, Sascha Hauer , kernel@pengutronix.de, festevam@gmail.com, linux-imx@nxp.com, tony@atomide.com, khilman@kernel.org, catalin.marinas@arm.com, will@kernel.org, guoren@kernel.org, bcain@quicinc.com, chenhuacai@kernel.org, kernel@xen0n.name, geert@linux-m68k.org, sammy@sammy.net, monstr@monstr.eu, tsbogend@alpha.franken.de, dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, James.Bottomley@HansenPartnership.com, deller@gmx.de, mpe@ellerman.id.au, benh@kernel.crashing.org, paulus@samba.org, paul.walmsley@sif Or better yet, try the patch that Rafael proposed. ;-) Thanx, Paul On Fri, Jul 29, 2022 at 08:26:22AM -0700, Paul E. McKenney wrote: > On Fri, Jul 29, 2022 at 03:24:58AM -0700, Michel Lespinasse wrote: > > On Thu, Jul 28, 2022 at 10:20:53AM -0700, Paul E. McKenney wrote: > > > On Mon, Jul 25, 2022 at 12:43:06PM -0700, Michel Lespinasse wrote: > > > > On Wed, Jun 08, 2022 at 04:27:27PM +0200, Peter Zijlstra wrote: > > > > > Commit c227233ad64c ("intel_idle: enable interrupts before C1 on > > > > > Xeons") wrecked intel_idle in two ways: > > > > > > > > > > - must not have tracing in idle functions > > > > > - must return with IRQs disabled > > > > > > > > > > Additionally, it added a branch for no good reason. > > > > > > > > > > Fixes: c227233ad64c ("intel_idle: enable interrupts before C1 on Xeons") > > > > > Signed-off-by: Peter Zijlstra (Intel) > > > > > > > > After this change was introduced, I am seeing "WARNING: suspicious RCU > > > > usage" when booting a kernel with debug options compiled in. Please > > > > see the attached dmesg output. The issue starts with commit 32d4fd5751ea > > > > and is still present in v5.19-rc8. > > > > > > > > I'm not sure, is this too late to fix or revert in v5.19 final ? > > > > > > I finally got a chance to take a quick look at this. > > > > > > The rcu_eqs_exit() function is making a lockdep complaint about > > > being invoked with interrupts enabled. This function is called from > > > rcu_idle_exit(), which is an expected code path from cpuidle_enter_state() > > > via its call to rcu_idle_exit(). Except that rcu_idle_exit() disables > > > interrupts before invoking rcu_eqs_exit(). > > > > > > The only other call to rcu_idle_exit() does not disable interrupts, > > > but it is via rcu_user_exit(), which would be a very odd choice for > > > cpuidle_enter_state(). > > > > > > It seems unlikely, but it might be that it is the use of local_irq_save() > > > instead of raw_local_irq_save() within rcu_idle_exit() that is causing > > > the trouble. If this is the case, then the commit shown below would > > > help. Note that this commit removes the warning from lockdep, so it > > > is necessary to build the kernel with CONFIG_RCU_EQS_DEBUG=y to enable > > > equivalent debugging. > > > > > > Could you please try your test with the -rce commit shown below applied? > > > > Thanks for looking into it. > > And thank you for trying this shot in the dark! > > > After checking out Peter's commit 32d4fd5751ea, > > cherry picking your commit ed4ae5eff4b3, > > and setting CONFIG_RCU_EQS_DEBUG=y in addition of my usual debug config, > > I am now seeing this a few seconds into the boot: > > > > [ 3.010650] ------------[ cut here ]------------ > > [ 3.010651] WARNING: CPU: 0 PID: 0 at kernel/sched/clock.c:397 sched_clock_tick+0x27/0x60 > > And this is again a complaint about interrupts not being disabled. > > But it does appear that the problem was the lockdep complaint, and > eliminating that did take care of part of the problem. But lockdep > remained enabled, and you therefore hit the next complaint. > > > [ 3.010657] Modules linked in: > > [ 3.010660] CPU: 0 PID: 0 Comm: swapper/0 Not tainted 5.19.0-rc1-test-00005-g1be22fea0611 #1 > > [ 3.010662] Hardware name: LENOVO 30BFS44D00/1036, BIOS S03KT51A 01/17/2022 > > [ 3.010663] RIP: 0010:sched_clock_tick+0x27/0x60 > > The most straightforward way to get to sched_clock_tick() from > cpuidle_enter_state() is via the call to sched_clock_idle_wakeup_event(). > > Except that it disables interrupts before invoking sched_clock_tick(). > > > [ 3.010665] Code: 1f 40 00 53 eb 02 5b c3 66 90 8b 05 2f c3 40 01 85 c0 74 18 65 8b 05 60 88 8f 4e 85 c0 75 0d 65 8b 05 a9 85 8f 4e 85 c0 74 02 <0f> 0b e8 e2 6c 89 00 48 c7 c3 40 d5 02 00 > > 89 c0 48 03 1c c5 c0 98 > > [ 3.010667] RSP: 0000:ffffffffb2803e28 EFLAGS: 00010002 > > [ 3.010670] RAX: 0000000000000001 RBX: ffffc8ce7fa07060 RCX: 0000000000000001 > > [ 3.010671] RDX: 0000000000000000 RSI: ffffffffb268dd21 RDI: ffffffffb269ab13 > > [ 3.010673] RBP: 0000000000000001 R08: ffffffffffc300d5 R09: 000000000002be80 > > [ 3.010674] R10: 000003625b53183a R11: ffffa012b802b7a4 R12: ffffffffb2aa9e80 > > [ 3.010675] R13: ffffffffb2aa9e00 R14: 0000000000000001 R15: 0000000000000000 > > [ 3.010677] FS: 0000000000000000(0000) GS:ffffa012b8000000(0000) knlGS:0000000000000000 > > [ 3.010678] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > > [ 3.010680] CR2: ffffa012f81ff000 CR3: 0000000c99612001 CR4: 00000000003706f0 > > [ 3.010681] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > > [ 3.010682] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 > > [ 3.010683] Call Trace: > > [ 3.010685] > > [ 3.010688] cpuidle_enter_state+0xb7/0x4b0 > > [ 3.010694] cpuidle_enter+0x29/0x40 > > [ 3.010697] do_idle+0x1d4/0x210 > > [ 3.010702] cpu_startup_entry+0x19/0x20 > > [ 3.010704] rest_init+0x117/0x1a0 > > [ 3.010708] arch_call_rest_init+0xa/0x10 > > [ 3.010711] start_kernel+0x6d8/0x6ff > > [ 3.010716] secondary_startup_64_no_verify+0xce/0xdb > > [ 3.010728] > > [ 3.010729] irq event stamp: 44179 > > [ 3.010730] hardirqs last enabled at (44179): [] asm_sysvec_apic_timer_interrupt+0x1b/0x20 > > [ 3.010734] hardirqs last disabled at (44177): [] __do_softirq+0x3f0/0x498 > > [ 3.010736] softirqs last enabled at (44178): [] __do_softirq+0x332/0x498 > > [ 3.010738] softirqs last disabled at (44171): [] irq_exit_rcu+0xab/0xf0 > > [ 3.010741] ---[ end trace 0000000000000000 ]--- > > Would you be willing to try another shot in the dark, but untested > this time? I freely admit that this is getting strange. > > Thanx, Paul > > ------------------------------------------------------------------------ > > diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c > index e374c0c923dae..279f557bf60bb 100644 > --- a/kernel/sched/clock.c > +++ b/kernel/sched/clock.c > @@ -394,7 +394,7 @@ notrace void sched_clock_tick(void) > if (!static_branch_likely(&sched_clock_running)) > return; > > - lockdep_assert_irqs_disabled(); > + WARN_ON_ONCE(IS_ENABLED(CONFIG_RCU_EQS_DEBUG) && !raw_irqs_disabled()); > > scd = this_scd(); > __scd_stamp(scd);