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[2604:1380:4601:e00::3]) by mx.google.com with ESMTPS id lt13-20020a170906fa8d00b00a367b5c7d40si2905951ejb.169.2024.02.04.06.53.13 for (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 04 Feb 2024 06:53:13 -0800 (PST) Received-SPF: pass (google.com: domain of linux-kernel+bounces-51733-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) client-ip=2604:1380:4601:e00::3; Authentication-Results: mx.google.com; dkim=pass header.i=@linux.alibaba.com header.s=default header.b="I/MkVhUM"; arc=pass (i=1 spf=pass spfdomain=linux.alibaba.com dkim=pass dkdomain=linux.alibaba.com dmarc=pass fromdomain=linux.alibaba.com); spf=pass (google.com: domain of linux-kernel+bounces-51733-ouuuleilei=gmail.com@vger.kernel.org designates 2604:1380:4601:e00::3 as permitted sender) smtp.mailfrom="linux-kernel+bounces-51733-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linux.alibaba.com Received: from smtp.subspace.kernel.org (wormhole.subspace.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by am.mirrors.kernel.org (Postfix) with ESMTPS id 851C21F22556 for ; Sun, 4 Feb 2024 14:53:12 +0000 (UTC) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by smtp.subspace.kernel.org (Postfix) with ESMTP id 8767F23749; Sun, 4 Feb 2024 14:52:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="I/MkVhUM" Received: from out30-124.freemail.mail.aliyun.com (out30-124.freemail.mail.aliyun.com [115.124.30.124]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id BB214224C6 for ; Sun, 4 Feb 2024 14:52:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.124 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707058332; cv=none; b=FsWTOYm01dO7YFAFrlMLWJFCya7eUN7B9vSCNDyaI6wP9ozH0orQf8d2T2LEawb+8Ma9YNpZKaFcI4X5DKjXNGEpuNeDN7I9dx9i/S034NszntMk41XssxFGZrz3NFpQZV3QPNsCfOnoPbtC1L4u0IY3kYXtuQVJz6RXXRfR/dU= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707058332; c=relaxed/simple; bh=qEsqwTImwSw6gIw+iNsI/NvF4mFQ4Yvcc4fFwgYXCNg=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=TWTMhZ32oReOU2fn67sTQZS2ViSxljAN9voQNaCg5F3oTrCOfBIwPjINukdSPp6HYe0lecJrYUV7ireJ0mjuSqW9Ob+hNQsGh09cic4tPFFfCl2kcYxdZVd0iOsJ2JBah/PFK4dN6mOJJXalb0EYkjaboEG59M0/RB+FHllItvs= ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com; spf=pass smtp.mailfrom=linux.alibaba.com; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b=I/MkVhUM; arc=none smtp.client-ip=115.124.30.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.alibaba.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.alibaba.com DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1707058321; h=From:To:Subject:Date:Message-Id:MIME-Version:Content-Type; bh=mQZuFgS/qBDlcnXbnMgoPKzPUcxHS7v5E5k+myd8QZY=; b=I/MkVhUMnC/J0wNeqlN3vZ4JnxNQ83qaGUY5bdL5XwmWrh8PLDmINkf35oWuYEjIM0Pn8P2eYkdFufsI5UZCdhwaCqbdVil9tfTgBgrnI5FDBUYbZkEX1BLckYkEG9V6MQnc1vNCPMtE8upAfQiYejYTIQldqHEwRtEqB9qefzw= X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046050;MF=yaoma@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0W00xOz6_1707058319; Received: from localhost.localdomain(mailfrom:yaoma@linux.alibaba.com fp:SMTPD_---0W00xOz6_1707058319) by smtp.aliyun-inc.com; Sun, 04 Feb 2024 22:52:01 +0800 From: Bitao Hu To: dianders@chromium.org, akpm@linux-foundation.org, pmladek@suse.com, kernelfans@gmail.com, liusong@linux.alibaba.com Cc: linux-kernel@vger.kernel.org, yaoma@linux.alibaba.com Subject: [PATCHv4 1/3] watchdog/softlockup: low-overhead detection of interrupt Date: Sun, 4 Feb 2024 22:51:52 +0800 Message-Id: <20240204145154.11069-2-yaoma@linux.alibaba.com> X-Mailer: git-send-email 2.37.1 (Apple Git-137.1) In-Reply-To: <20240204145154.11069-1-yaoma@linux.alibaba.com> References: <20240204145154.11069-1-yaoma@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1789980461705460575 X-GMAIL-MSGID: 1789980461705460575 The following softlockup is caused by interrupt storm, but it cannot be identified from the call tree. Because the call tree is just a snapshot and doesn't fully capture the behavior of the CPU during the soft lockup. watchdog: BUG: soft lockup - CPU#28 stuck for 23s! [fio:83921] ... Call trace: __do_softirq+0xa0/0x37c __irq_exit_rcu+0x108/0x140 irq_exit+0x14/0x20 __handle_domain_irq+0x84/0xe0 gic_handle_irq+0x80/0x108 el0_irq_naked+0x50/0x58 Therefore，I think it is necessary to report CPU utilization during the softlockup_thresh period (report once every sample_period, for a total of 5 reportings), like this: watchdog: BUG: soft lockup - CPU#28 stuck for 23s! [fio:83921] CPU#28 Utilization every 4s during lockup: #1: 0% system, 0% softirq, 100% hardirq, 0% idle #2: 0% system, 0% softirq, 100% hardirq, 0% idle #3: 0% system, 0% softirq, 100% hardirq, 0% idle #4: 0% system, 0% softirq, 100% hardirq, 0% idle #5: 0% system, 0% softirq, 100% hardirq, 0% idle ... This would be helpful in determining whether an interrupt storm has occurred or in identifying the cause of the softlockup. The criteria for determination are as follows: a. If the hardirq utilization is high, then interrupt storm should be considered and the root cause cannot be determined from the call tree. b. If the softirq utilization is high, then we could analyze the call tree but it may cannot reflect the root cause. c. If the system utilization is high, then we could analyze the root cause from the call tree. Signed-off-by: Bitao Hu Reviewed-by: Liu Song --- kernel/watchdog.c | 91 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 91 insertions(+) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 81a8862295d6..7b121e166b81 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -16,6 +16,8 @@ #include #include #include +#include +#include #include #include #include @@ -333,6 +335,92 @@ __setup("watchdog_thresh=", watchdog_thresh_setup); static void __lockup_detector_cleanup(void); +#ifdef CONFIG_IRQ_TIME_ACCOUNTING +#define NUM_STATS_GROUPS 5 +enum stats_per_group { + STATS_SYSTEM, + STATS_SOFTIRQ, + STATS_HARDIRQ, + STATS_IDLE, + NUM_STATS_PER_GROUP, +}; +static const enum cpu_usage_stat tracked_stats[NUM_STATS_PER_GROUP] = { + CPUTIME_SYSTEM, + CPUTIME_SOFTIRQ, + CPUTIME_IRQ, + CPUTIME_IDLE, +}; +static DEFINE_PER_CPU(u16, cpustat_old[NUM_STATS_PER_GROUP]); +static DEFINE_PER_CPU(u8, cpustat_util[NUM_STATS_GROUPS][NUM_STATS_PER_GROUP]); +static DEFINE_PER_CPU(u8, cpustat_tail); + +/* + * We don't need nanosecond resolution. A granularity of 16ms is + * sufficient for our precision, allowing us to use u16 to store + * cpustats, which will roll over roughly every ~1000 seconds. + * 2^24 ~= 16 * 10^6 + */ +static u16 get_16bit_precision(u64 data_ns) +{ + return data_ns >> 24LL; /* 2^24ns ~= 16.8ms */ +} + +static void update_cpustat(void) +{ + int i; + u8 util; + u16 old_stat; + u16 new_stat; + u8 tail = __this_cpu_read(cpustat_tail); + struct kernel_cpustat kcpustat; + u64 *cpustat = kcpustat.cpustat; + u16 sample_period_16 = get_16bit_precision(sample_period); + + kcpustat_cpu_fetch(&kcpustat, smp_processor_id()); + for (i = 0; i < NUM_STATS_PER_GROUP; i++) { + old_stat = __this_cpu_read(cpustat_old[i]); + new_stat = get_16bit_precision(cpustat[tracked_stats[i]]); + util = DIV_ROUND_UP(100 * (new_stat - old_stat), sample_period_16); + __this_cpu_write(cpustat_util[tail][i], util); + __this_cpu_write(cpustat_old[i], new_stat); + } + __this_cpu_write(cpustat_tail, (tail + 1) % NUM_STATS_GROUPS); +} + +static void print_cpustat(void) +{ + int i; + int group; + u8 tail = __this_cpu_read(cpustat_tail); + u64 sample_period_second = sample_period; + + do_div(sample_period_second, NSEC_PER_SEC); + /* + * We do not want the "watchdog: " prefix on every line, + * hence we use "printk" instead of "pr_crit". + */ + printk(KERN_CRIT "CPU#%d Utilization every %llus during lockup:\n", + smp_processor_id(), sample_period_second); + for (i = 0; i < NUM_STATS_GROUPS; i++) { + group = (tail + i) % NUM_STATS_GROUPS; + printk(KERN_CRIT "\t#%d: %3u%% system,\t%3u%% softirq,\t" + "%3u%% hardirq,\t%3u%% idle\n", i+1, + __this_cpu_read(cpustat_util[group][STATS_SYSTEM]), + __this_cpu_read(cpustat_util[group][STATS_SOFTIRQ]), + __this_cpu_read(cpustat_util[group][STATS_HARDIRQ]), + __this_cpu_read(cpustat_util[group][STATS_IDLE])); + } +} + +static void report_cpu_status(void) +{ + print_cpustat(); +} +#else +static inline void update_cpustat(void) { } +static inline void report_cpu_status(void) { } +#endif + /* * Hard-lockup warnings should be triggered after just a few seconds. Soft- * lockups can have false positives under extreme conditions. So we generally @@ -504,6 +592,8 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) */ period_ts = READ_ONCE(*this_cpu_ptr(&watchdog_report_ts)); + update_cpustat(); + /* Reset the interval when touched by known problematic code. */ if (period_ts == SOFTLOCKUP_DELAY_REPORT) { if (unlikely(__this_cpu_read(softlockup_touch_sync))) { @@ -539,6 +629,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", smp_processor_id(), duration, current->comm, task_pid_nr(current)); + report_cpu_status(); print_modules(); print_irqtrace_events(current); if (regs) From patchwork Sun Feb 4 14:51:54 2024 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Bitao Hu X-Patchwork-Id: 196519 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a05:7301:168b:b0:106:860b:bbdd with SMTP id ma11csp387718dyb; Sun, 4 Feb 2024 06:53:42 -0800 (PST) X-Google-Smtp-Source: AGHT+IHJMaM6kaxk4bmOvNnm9bb7tRObw9C2FtL01S8NoOax6MGN6oAFImj5FG/1jGlalN50NBTK X-Received: by 2002:a05:6808:238c:b0:3bf:cd78:6776 with SMTP id bp12-20020a056808238c00b003bfcd786776mr6052755oib.22.1707058422518; Sun, 04 Feb 2024 06:53:42 -0800 (PST) ARC-Seal: i=2; a=rsa-sha256; t=1707058422; cv=pass; d=google.com; s=arc-20160816; b=TeFLjo38sgt74NbMaYuJ9091HfO9EDzZOCBeI2Tj8QpPpVz+g5hrwtQAb0OaClcuXN PMcCDSR6UyMkYQTzO1MokO317yd6c5c0cGfmhcSFjS5iR3b3UYMFX4WmWB3DJEcpya9y kCjD48zMMKf4N1MtX9MSxWRwBhDREyOQckT2RWGFfHECQUEc5h7/B7ef/CtVUZBA9ULs syWDNNOHWqVPx9iD0BfEYs8BcwhG+f23YasIvW3Tg1j9HWdnR55l3580MdidAj2yolJp U0lN/EZenYRbIoCVqGtLVjaG3pz4XHexiJC8NqDjiIY8GqK0T4M6n3Bt2QlfAgAwwRHM iV8g== ARC-Message-Signature: i=2; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=content-transfer-encoding:mime-version:list-unsubscribe :list-subscribe:list-id:precedence:references:in-reply-to:message-id :date:subject:cc:to:from:dkim-signature; bh=1aIE2l+wx3ThQkg4ZY8lGbbMkz4SlO/OXHAps4v7kP4=; fh=NL5wNBw25ifgpT6hp2WtGjxTaSGJlIdtmS2ipY0Bz9Y=; b=FQRw3//YzqKMrIEJ5XTbritMR7NYdQ/CoFPPN30/JtLepBVqQGRhzQvWE1Pc/Cq679 /1iXwDQE16Arpc3m69PEoSDnlMkJXDQ8riCAoGQNanSowSNw4GBSDKm2DvTtfSC2uznP EZp7AuVabkYd9PwY4kSa4pKx2fbQpkxsfxL2MAVeCIq5dHrAu08BrcE8jTtXkFGMVPX6 J7AWgUMxF6+Ac7jPXZqsG1pm9pupwnwjSSIRvkXSYp04xwybAGnDeeNnJvqOjQgqqMu+ dEr5i9c0vFO5NphDbBoRPsveKoIZEx5Cj4xUNnu1W+Oz04AsP4quY6UrgtHzNj04aFnK e5xw==; dara=google.com ARC-Authentication-Results: i=2; mx.google.com; dkim=pass header.i=@linux.alibaba.com header.s=default header.b=oPEUsN4s; arc=pass (i=1 spf=pass spfdomain=linux.alibaba.com dkim=pass dkdomain=linux.alibaba.com dmarc=pass fromdomain=linux.alibaba.com); spf=pass (google.com: domain of linux-kernel+bounces-51735-ouuuleilei=gmail.com@vger.kernel.org designates 147.75.48.161 as permitted sender) smtp.mailfrom="linux-kernel+bounces-51735-ouuuleilei=gmail.com@vger.kernel.org"; dmarc=pass (p=NONE sp=NONE dis=NONE) header.from=linux.alibaba.com X-Forwarded-Encrypted: i=1; AJvYcCWWYud6kU74Jw1/d5PlV1aeOHZR7pHmV6d+Oc1dALxRt3auvUecxzwYUpJzHV082mfaZ2XiBGNKbvBN8UKfX//rjTPb/A== Received: from sy.mirrors.kernel.org (sy.mirrors.kernel.org. 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Therefore, adding a SOFTLOCKUP_DETECTOR_INTR_STORM Kconfig knob that defaults to "yes" if the max number of CPUs is <= 128. Signed-off-by: Bitao Hu --- kernel/watchdog.c | 2 +- lib/Kconfig.debug | 13 +++++++++++++ 2 files changed, 14 insertions(+), 1 deletion(-) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index d31120c3e9d1..a2722935a381 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -338,7 +338,7 @@ __setup("watchdog_thresh=", watchdog_thresh_setup); static void __lockup_detector_cleanup(void); -#ifdef CONFIG_IRQ_TIME_ACCOUNTING +#ifdef CONFIG_SOFTLOCKUP_DETECTOR_INTR_STORM #define NUM_STATS_GROUPS 5 enum stats_per_group { STATS_SYSTEM, diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 975a07f9f1cc..74002ba7c42d 100644 --- a/lib/Kconfig.debug +++ b/lib/Kconfig.debug @@ -1029,6 +1029,19 @@ config SOFTLOCKUP_DETECTOR chance to run. The current stack trace is displayed upon detection and the system will stay locked up. +config SOFTLOCKUP_DETECTOR_INTR_STORM + bool "Detect Interrupt Storm in Soft Lockups" + depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING + default y if NR_CPUS <= 128 + help + Say Y here to enable the kernel to detect interrupt storm + during "soft lockups". + + "soft lockups" can be caused by a variety of reasons. If one is caused by + an interrupt storm, then the storming interrupts will not be on the + callstack. To detect this case, it is necessary to report the CPU stats + and the interrupt counts during the "soft lockups". + config BOOTPARAM_SOFTLOCKUP_PANIC bool "Panic (Reboot) On Soft Lockups" depends on SOFTLOCKUP_DETECTOR