From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 2B630C2D0A8 for ; Mon, 28 Sep 2020 13:00:06 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AF7042068E for ; Mon, 28 Sep 2020 13:00:05 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="io9TxdZf" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726500AbgI1NAE (ORCPT ); Mon, 28 Sep 2020 09:00:04 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54518 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726281AbgI1NAE (ORCPT ); Mon, 28 Sep 2020 09:00:04 -0400 Received: from merlin.infradead.org (merlin.infradead.org [IPv6:2001:8b0:10b:1231::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 134B8C061755 for ; Mon, 28 Sep 2020 06:00:04 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=WiurnCcHfhcaqE4SKB4xvzlGUq8igqVJxtqs9UacGwM=; b=io9TxdZftAgyQVbFKc+eX7yw3g YnmvYm6/9cVoePZNjRulruhmXHa9BZ0ZM9XLBjd5PRMJCdDpbbVUYTL4HEnD02XymPoI74W1lGHRt xsvP9J52Ku0rqQgGf0gIvJXUJWWYMV9hIuUgvb/ZpaJPdlGS1UYJhSENRIPzZZEafYpkFaepj01g4 AkhfXgy6IWthYsq5m+lCPcoPQLhyjzFm4lJPKb6xy6UcVtMstRXGVlNOC82KdjuuTbVFYXid4Utms Om6HMYKxgpO9OlHtdAPeZDFZa0mHjGpFihYVcbSkP4aN1f0gAPjp6uNQS5yei1y/S46xdQOuOGwIy MnveUm2g==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1kMskp-0001U6-5j; Mon, 28 Sep 2020 12:59:43 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 1FD12300DB4; Mon, 28 Sep 2020 14:59:38 +0200 (CEST) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id D5E422006F633; Mon, 28 Sep 2020 14:59:38 +0200 (CEST) Date: Mon, 28 Sep 2020 14:59:38 +0200 From: Peter Zijlstra To: Aisheng Dong Cc: "rostedt@goodmis.org" , Thomas Gleixner , "Rafael J . Wysocki" , "elver@google.com" , "linux-kernel@vger.kernel.org" , dl-linux-imx , "linux-arm-kernel@lists.infradead.org" , Shawn Guo , Anson Huang , Jacky Bai , Sascha Hauer , ulf.hansson@linaro.org Subject: Re: cpudile warning on mx6q sabresd caused by eb1f00237aca ("lockdep,trace: Expose tracepoints") Message-ID: <20200928125938.GG2628@hirez.programming.kicks-ass.net> References: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Sep 28, 2020 at 12:26:58PM +0000, Aisheng Dong wrote: > Hi Peter, > > We met a cpudile warning on mx6q sabresd board since v5.9-rc3 and also exist in latest linux-next (next-20200925). > After some bisection, I found it’s caused by below patch. > Any suggestions about this issue? The word is 'exposed', not 'caused', these are pre-existing bugs. > [ 6.870684] [] (_raw_spin_lock) from [] (imx6q_enter_wait+0x18/0x9c) > [ 6.878846] [] (imx6q_enter_wait) from [] (cpuidle_enter_state+0x168/0x5e4) I'm not really familiar with all the oddities of ARM cpuidle, but one possible way is similar to this commit. commit 1fecfdbb7acc6624655450a609221c89b5197a06 Author: Peter Zijlstra Date: Tue Sep 15 12:32:01 2020 +0200 ACPI: processor: Take over RCU-idle for C3-BM idle The C3 BusMaster idle code takes lock in a number of places, some deep inside the ACPI code. Instead of wrapping it all in RCU_NONIDLE, have the driver take over RCU-idle duty and avoid flipping RCU state back and forth a lot. ( by marking 'C3 && bm_check' as RCU_IDLE, we _must_ call enter_bm() for that combination, otherwise we'll loose RCU-idle, this requires shuffling some code around ) Signed-off-by: Peter Zijlstra (Intel) Tested-by: Borislav Petkov Signed-off-by: Rafael J. Wysocki diff --git a/drivers/acpi/processor_idle.c b/drivers/acpi/processor_idle.c index 9ec504067f98..7ecb90e90afd 100644 --- a/drivers/acpi/processor_idle.c +++ b/drivers/acpi/processor_idle.c @@ -558,22 +558,43 @@ static DEFINE_RAW_SPINLOCK(c3_lock); /** * acpi_idle_enter_bm - enters C3 with proper BM handling + * @drv: cpuidle driver * @pr: Target processor * @cx: Target state context + * @index: index of target state */ -static void acpi_idle_enter_bm(struct acpi_processor *pr, - struct acpi_processor_cx *cx) +static int acpi_idle_enter_bm(struct cpuidle_driver *drv, + struct acpi_processor *pr, + struct acpi_processor_cx *cx, + int index) { + static struct acpi_processor_cx safe_cx = { + .entry_method = ACPI_CSTATE_HALT, + }; + /* * disable bus master * bm_check implies we need ARB_DIS * bm_control implies whether we can do ARB_DIS * - * That leaves a case where bm_check is set and bm_control is - * not set. In that case we cannot do much, we enter C3 - * without doing anything. + * That leaves a case where bm_check is set and bm_control is not set. + * In that case we cannot do much, we enter C3 without doing anything. */ - if (pr->flags.bm_control) { + bool dis_bm = pr->flags.bm_control; + + /* If we can skip BM, demote to a safe state. */ + if (!cx->bm_sts_skip && acpi_idle_bm_check()) { + dis_bm = false; + index = drv->safe_state_index; + if (index >= 0) { + cx = this_cpu_read(acpi_cstate[index]); + } else { + cx = &safe_cx; + index = -EBUSY; + } + } + + if (dis_bm) { raw_spin_lock(&c3_lock); c3_cpu_count++; /* Disable bus master arbitration when all CPUs are in C3 */ @@ -582,15 +603,21 @@ static void acpi_idle_enter_bm(struct acpi_processor *pr, raw_spin_unlock(&c3_lock); } + rcu_idle_enter(); + acpi_idle_do_entry(cx); + rcu_idle_exit(); + /* Re-enable bus master arbitration */ - if (pr->flags.bm_control) { + if (dis_bm) { raw_spin_lock(&c3_lock); acpi_write_bit_register(ACPI_BITREG_ARB_DISABLE, 0); c3_cpu_count--; raw_spin_unlock(&c3_lock); } + + return index; } static int acpi_idle_enter(struct cpuidle_device *dev, @@ -604,20 +631,13 @@ static int acpi_idle_enter(struct cpuidle_device *dev, return -EINVAL; if (cx->type != ACPI_STATE_C1) { + if (cx->type == ACPI_STATE_C3 && pr->flags.bm_check) + return acpi_idle_enter_bm(drv, pr, cx, index); + + /* C2 to C1 demotion. */ if (acpi_idle_fallback_to_c1(pr) && num_online_cpus() > 1) { index = ACPI_IDLE_STATE_START; cx = per_cpu(acpi_cstate[index], dev->cpu); - } else if (cx->type == ACPI_STATE_C3 && pr->flags.bm_check) { - if (cx->bm_sts_skip || !acpi_idle_bm_check()) { - acpi_idle_enter_bm(pr, cx); - return index; - } else if (drv->safe_state_index >= 0) { - index = drv->safe_state_index; - cx = per_cpu(acpi_cstate[index], dev->cpu); - } else { - acpi_safe_halt(); - return -EBUSY; - } } } @@ -641,7 +661,13 @@ static int acpi_idle_enter_s2idle(struct cpuidle_device *dev, return 0; if (pr->flags.bm_check) { - acpi_idle_enter_bm(pr, cx); + u8 bm_sts_skip = cx->bm_sts_skip; + + /* Don't check BM_STS, do an unconditional ARB_DIS for S2IDLE */ + cx->bm_sts_skip = 1; + acpi_idle_enter_bm(drv, pr, cx, index); + cx->bm_sts_skip = bm_sts_skip; + return 0; } else { ACPI_FLUSH_CPU_CACHE(); @@ -674,8 +700,11 @@ static int acpi_processor_setup_cpuidle_cx(struct acpi_processor *pr, if (lapic_timer_needs_broadcast(pr, cx)) state->flags |= CPUIDLE_FLAG_TIMER_STOP; - if (cx->type == ACPI_STATE_C3) + if (cx->type == ACPI_STATE_C3) { state->flags |= CPUIDLE_FLAG_TLB_FLUSHED; + if (pr->flags.bm_check) + state->flags |= CPUIDLE_FLAG_RCU_IDLE; + } count++; if (count == CPUIDLE_STATE_MAX)