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 5C6AFC19F2A for ; Sat, 30 Jul 2022 19:52:54 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235688AbiG3Tww (ORCPT ); Sat, 30 Jul 2022 15:52:52 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58680 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230337AbiG3Tws (ORCPT ); Sat, 30 Jul 2022 15:52:48 -0400 Received: from mail-yb1-f179.google.com (mail-yb1-f179.google.com [209.85.219.179]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0127E13F39; Sat, 30 Jul 2022 12:52:46 -0700 (PDT) Received: by mail-yb1-f179.google.com with SMTP id n8so13219366yba.2; Sat, 30 Jul 2022 12:52:46 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=cc:to:subject:message-id:date:from:in-reply-to:references :mime-version:x-gm-message-state:from:to:cc; bh=0QwwjVOIVs4sR9ljVmsJX6Xu2S4+tvcr+oBVAjM+ePA=; b=e8a+uAA9tupGiL3yo8EkLFat/Yo8hfOL0dEjkN03EunifrpH5WDt1ik8Q1l2EEocjT fVLKUVbPQ9p/jM9rZc9eF9zc1WhebYD91WFyUJRwIVfjf9eCUMB2ZXT2bKXo1vYd8xMc 50i0dubF4/84MjJhKF4f85UL/b1J0h+2706rL4zlKw4tJHsRIFOrc5kAycR6TXvyhJ9j CllXK+t+T+a1NuZN8RfaIE0i+YPlr+Ffb4JjIxKgdpkG9WV3WEADKavvYeM3AYhjh8Iu gcsyrORxqg7xbZQpjRPJZ9seachiStWce2u60xdb874MBo8w5IRxW8i7Qr+4fXWv/6+q E64w== X-Gm-Message-State: ACgBeo3OxYk4mfg72HXbMBbEY4LajVRBqucZ4mdHqCYye8RS04nh7S16 hmWROudYRZmXM0tYeJDe4uYZSSldbIvoGgz0A8I= X-Google-Smtp-Source: AA6agR5p+lnEO42NEIBehm6hZLFrmXewKv2ogwUWOYz3LvGYShyipeAc9YxoFpIxLibrvw9Jcl6WeqKY+cLq4G0/mNE= X-Received: by 2002:a25:3458:0:b0:673:5bca:3b45 with SMTP id b85-20020a253458000000b006735bca3b45mr6304433yba.633.1659210766011; Sat, 30 Jul 2022 12:52:46 -0700 (PDT) MIME-Version: 1.0 References: <20220608142723.103523089@infradead.org> <20220608144516.172460444@infradead.org> <20220725194306.GA14746@lespinasse.org> <20220728172053.GA3607379@paulmck-ThinkPad-P17-Gen-1> <20220729102458.GA1695@lespinasse.org> <20220730094800.GB1587@lespinasse.org> In-Reply-To: <20220730094800.GB1587@lespinasse.org> From: "Rafael J. Wysocki" Date: Sat, 30 Jul 2022 21:52:34 +0200 Message-ID: Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE To: Michel Lespinasse Cc: "Rafael J. Wysocki" , "Paul E. McKenney" , Peter Zijlstra , Richard Henderson , Ivan Kokshaysky , Matt Turner , vgupta@kernel.org, Russell King - ARM Linux , ulli.kroll@googlemail.com, Linus Walleij , Shawn Guo , Sascha Hauer , Sascha Hauer , Fabio Estevam , dl-linux-imx , Tony Lindgren , Kevin Hilman , Catalin Marinas , Will Deacon , Guo Ren , bcain@quicinc.com, Huacai Chen , kernel@xen0n.name, Geert Uytterhoeven , sammy@sammy.net, Michal Simek , Thomas Bogendoerfer , dinguyen@kernel.org, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, Stafford Horne , James Bottomley , Helge Deller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras , Paul Walmsley , Palmer Dabbelt , Albert Ou , Heiko Carstens , Vasily Gorbik , Alexander Gordeev , Christian Borntraeger , Sven Schnelle , Yoshinori Sato , Rich Felker , David Miller , Richard Weinberger , anton.ivanov@cambridgegreys.com, Johannes Berg , Thomas Gleixner , Ingo Molnar , Borislav Petkov , Dave Hansen , "the arch/x86 maintainers" , "H. Peter Anvin" , acme@kernel.org, Mark Rutland , Alexander Shishkin , jolsa@kernel.org, namhyung@kernel.org, Juergen Gross , srivatsa@csail.mit.edu, amakhalov@vmware.com, pv-drivers@vmware.com, Boris Ostrovsky , Chris Zankel , Max Filippov , Len Brown , Pavel Machek , Greg Kroah-Hartman , Michael Turquette , Stephen Boyd , Daniel Lezcano , Lorenzo Pieralisi , Sudeep Holla , Andy Gross , Bjorn Andersson , Anup Patel , Thierry Reding , Jon Hunter , Jacob Pan , Arnd Bergmann , Yury Norov , Andy Shevchenko , Rasmus Villemoes , Steven Rostedt , Petr Mladek , senozhatsky@chromium.org, John Ogness , Frederic Weisbecker , quic_neeraju@quicinc.com, Josh Triplett , Mathieu Desnoyers , Lai Jiangshan , Joel Fernandes , Juri Lelli , Vincent Guittot , Dietmar Eggemann , Benjamin Segall , Mel Gorman , Daniel Bristot de Oliveira , vschneid@redhat.com, jpoimboe@kernel.org, linux-alpha@vger.kernel.org, Linux Kernel Mailing List , linux-snps-arc@lists.infradead.org, Linux ARM , Linux OMAP Mailing List , linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-ia64@vger.kernel.org, linux-m68k , "open list:BROADCOM NVRAM DRIVER" , openrisc@lists.librecores.org, Parisc List , linuxppc-dev , linux-riscv , linux-s390@vger.kernel.org, Linux-sh list , 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, ACPI Devel Maling List , Linux PM , linux-clk , linux-arm-msm , linux-tegra , linux-arch , rcu@vger.kernel.org, rh0@fb.com Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org On Sat, Jul 30, 2022 at 11:48 AM Michel Lespinasse wrote: > > On Fri, Jul 29, 2022 at 04:59:50PM +0200, Rafael J. Wysocki wrote: > > On Fri, Jul 29, 2022 at 12:25 PM 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. > > > > > > 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 > > > [ 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 > > > [ 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 ]--- > > > > Can you please give this patch a go: > > https://patchwork.kernel.org/project/linux-pm/patch/Yt/AxPFi88neW7W5@e126311.manchester.arm.com/ > > ? > > I tried, but it didn't change the picture for me. > > I'm not sure if that was the patch you meant to send though, as it > seems it's only adding a tracepoint so shouldn't make any difference > if I'm not actually using the tracepoint ? You are right, it looks like I pasted a link to a different patch by mistake. Sorry about that. I meant this one: https://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm.git/commit/?h=pm&id=d295ad34f236c3518634fb6403d4c0160456e470 which will appear in the final 5.19.