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 CDECBC25B07 for ; Sat, 30 Jul 2022 09:48:19 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S237088AbiG3JsR (ORCPT ); Sat, 30 Jul 2022 05:48:17 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45324 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231919AbiG3JsD (ORCPT ); Sat, 30 Jul 2022 05:48:03 -0400 Received: from server.lespinasse.org (server.lespinasse.org [63.205.204.226]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 625BB21838; Sat, 30 Jul 2022 02:48:01 -0700 (PDT) DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=lespinasse.org; i=@lespinasse.org; q=dns/txt; s=srv-79-ed; t=1659174480; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to : from; bh=Zxf3RSaNJoCIr1yVDJrzk/JbWyKzetatYmCU4rexx90=; b=cZU78DKx8pFQT/pgVoRK+oC1CZy06YVs0Ncnf0QaLcl424By3Kjx5CkEiKeOCe5qVRr6F d5VUO89u24wx67IDg== DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=lespinasse.org; i=@lespinasse.org; q=dns/txt; s=srv-79-rsa; t=1659174480; h=date : from : to : cc : subject : message-id : references : mime-version : content-type : in-reply-to : from; bh=Zxf3RSaNJoCIr1yVDJrzk/JbWyKzetatYmCU4rexx90=; b=E7bNTGGoLCtSak6vdo2mcsTxCf1hzf0BGfTJf+3fxNW8XoC1Irg25HKARFJxMUqglwRiZ /+PtdJukPF4I7dMchFGuOTlc6HF+ILudreHXspZ5+iq1EUo4O8wMtq/TUdXSHXBaa5SJ3NO jNncE1xXfEZDGhm9tVuTZARivwI3g2bOG161J6kIR/uneTxU5u8uosRneQGgcxDKcMpS14k VDxLDCrjKG2W1akV+QJCTqjuPVvOs13Tc5A3x81JQOC51BYOxcxo1P+tMKYHnkvyMojBpOI ML3j+Tx2rQv8aS6U1W+HYjpeQRsMxu/Pw3oIh4x81I9GbWbHHfVrH8MXwhjw== Received: by server.lespinasse.org (Postfix, from userid 1000) id B784116096F; Sat, 30 Jul 2022 02:48:00 -0700 (PDT) Date: Sat, 30 Jul 2022 02:48:00 -0700 From: Michel Lespinasse To: "Rafael J. Wysocki" Cc: Michel Lespinasse , "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 Subject: Re: [PATCH 04/36] cpuidle,intel_idle: Fix CPUIDLE_FLAG_IRQ_ENABLE Message-ID: <20220730094800.GB1587@lespinasse.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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.10.1 (2018-07-13) Precedence: bulk List-ID: X-Mailing-List: linux-pm@vger.kernel.org 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 ?