From nobody Sat Feb 7 13:45:58 2026 Received: from out30-133.freemail.mail.aliyun.com (out30-133.freemail.mail.aliyun.com [115.124.30.133]) (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 52F6A6127 for ; Wed, 14 Feb 2024 02:19:54 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.133 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707877198; cv=none; b=jz04SbnYucZHARAuhkcXxrSlV4w3SGpeVBubDfouQFz7rRD3WgdPR1+SWgi1VNFcTRKUAFSCPVAWhrGv+qtHwUEOAN1twSig4DahBDOuuzOpbOLICrwX3tbAmZ5WOwWADb5/BrBfv2phweKnxHtp+lFxWyCP9HSn/ChJGaL0MXM= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707877198; c=relaxed/simple; bh=YyGVL3DTq1NGBUlNTsaZWPygzXSkQqFhl2iQhk+tfEY=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version:Content-Type; b=oXaX2MROKDA6es/C9+I4vkiOZi2/zyV52j1Ow7xTlCcEBFY+B07MauAyCACSiMVvP2Y69zq8kXdv4Xbtf4d1SkaCKnRNvSIIaKBYtycSHgLU6cIRNAWBJwDLvhoH/sicskdbUF4KFNc32NnOIxzXl4sY8LCamUed18E8SA/lnEU= 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=ZXhQZUBz; arc=none smtp.client-ip=115.124.30.133 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="ZXhQZUBz" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1707877193; h=From:To:Subject:Date:Message-Id:MIME-Version:Content-Type; bh=nB7HiCRDXz45RwbXKMqlhFZOk/rJjNAZ2WqhNw3OoCA=; b=ZXhQZUBzazO+hITzY49+zCe65x+v1lIO/7bnKHnfzAmIHiT8PB8y6dr9nkwoTWVRFuAOhAAuXK1HSrX/8BBuOSIq6PkfeLRJuDuFDjSUP8P/mDXJFI02AKLQYUQCpeJ7vMz63JNYcs9X5ce+V0/GC7mLNfOCLfPgM8W3kjRTU30= X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046059;MF=yaoma@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0W0b-9Ff_1707876875; Received: from localhost.localdomain(mailfrom:yaoma@linux.alibaba.com fp:SMTPD_---0W0b-9Ff_1707876875) by smtp.aliyun-inc.com; Wed, 14 Feb 2024 10:14:36 +0800 From: Bitao Hu To: dianders@chromium.org, akpm@linux-foundation.org, pmladek@suse.com, kernelfans@gmail.com, liusong@linux.alibaba.com Cc: yaoma@linux.alibaba.com, linux-kernel@vger.kernel.org Subject: [PATCHv7 1/2] watchdog/softlockup: low-overhead detection of interrupt Date: Wed, 14 Feb 2024 10:14:29 +0800 Message-Id: <20240214021430.87471-2-yaoma@linux.alibaba.com> X-Mailer: git-send-email 2.37.1 (Apple Git-137.1) In-Reply-To: <20240214021430.87471-1-yaoma@linux.alibaba.com> References: <20240214021430.87471-1-yaoma@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable 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=EF=BC=8CI 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. The mechanism requires a considerable amount of global storage space when configured for the maximum number of CPUs. Therefore, adding a SOFTLOCKUP_DETECTOR_INTR_STORM Kconfig knob that defaults to "yes" if the max number of CPUs is <=3D 128. Signed-off-by: Bitao Hu Reviewed-by: Douglas Anderson Reviewed-by: Liu Song --- kernel/watchdog.c | 98 ++++++++++++++++++++++++++++++++++++++++++++++- lib/Kconfig.debug | 13 +++++++ 2 files changed, 110 insertions(+), 1 deletion(-) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 81a8862295d6..69e72d7e461d 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -16,6 +16,8 @@ #include #include #include +#include +#include #include #include #include @@ -35,6 +37,8 @@ static DEFINE_MUTEX(watchdog_mutex); # define WATCHDOG_HARDLOCKUP_DEFAULT 0 #endif =20 +#define NUM_SAMPLE_PERIODS 5 + unsigned long __read_mostly watchdog_enabled; int __read_mostly watchdog_user_enabled =3D 1; static int __read_mostly watchdog_hardlockup_user_enabled =3D WATCHDOG_HAR= DLOCKUP_DEFAULT; @@ -333,6 +337,95 @@ __setup("watchdog_thresh=3D", watchdog_thresh_setup); =20 static void __lockup_detector_cleanup(void); =20 +#ifdef CONFIG_SOFTLOCKUP_DETECTOR_INTR_STORM +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] =3D { + 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_SAMPLE_PERIODS][NUM_STATS_PER_G= ROUP]); +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 ~=3D 16 * 10^6 + */ +static u16 get_16bit_precision(u64 data_ns) +{ + return data_ns >> 24LL; /* 2^24ns ~=3D 16.8ms */ +} + +static void update_cpustat(void) +{ + int i; + u8 util; + u16 old_stat, new_stat; + struct kernel_cpustat kcpustat; + u64 *cpustat =3D kcpustat.cpustat; + u8 tail =3D __this_cpu_read(cpustat_tail); + u16 sample_period_16 =3D get_16bit_precision(sample_period); + + kcpustat_cpu_fetch(&kcpustat, smp_processor_id()); + + for (i =3D 0; i < NUM_STATS_PER_GROUP; i++) { + old_stat =3D __this_cpu_read(cpustat_old[i]); + new_stat =3D get_16bit_precision(cpustat[tracked_stats[i]]); + util =3D 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_SAMPLE_PERIODS); +} + +static void print_cpustat(void) +{ + int i, group; + u8 tail =3D __this_cpu_read(cpustat_tail); + u64 sample_period_second =3D 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 =3D 0; i < NUM_SAMPLE_PERIODS; i++) { + group =3D (tail + i) % NUM_SAMPLE_PERIODS; + 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 genera= lly @@ -364,7 +457,7 @@ static void set_sample_period(void) * and hard thresholds) to increment before the * hardlockup detector generates a warning */ - sample_period =3D get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5); + sample_period =3D get_softlockup_thresh() * ((u64)NSEC_PER_SEC / NUM_SAMP= LE_PERIODS); watchdog_update_hrtimer_threshold(sample_period); } =20 @@ -504,6 +597,8 @@ static enum hrtimer_restart watchdog_timer_fn(struct hr= timer *hrtimer) */ period_ts =3D READ_ONCE(*this_cpu_ptr(&watchdog_report_ts)); =20 + update_cpustat(); + /* Reset the interval when touched by known problematic code. */ if (period_ts =3D=3D SOFTLOCKUP_DELAY_REPORT) { if (unlikely(__this_cpu_read(softlockup_touch_sync))) { @@ -539,6 +634,7 @@ static enum hrtimer_restart watchdog_timer_fn(struct hr= timer *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) diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug index 975a07f9f1cc..49f652674bd8 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. =20 +config SOFTLOCKUP_DETECTOR_INTR_STORM + bool "Detect Interrupt Storm in Soft Lockups" + depends on SOFTLOCKUP_DETECTOR && IRQ_TIME_ACCOUNTING + default y if NR_CPUS <=3D 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 --=20 2.37.1 (Apple Git-137.1) From nobody Sat Feb 7 13:45:58 2026 Received: from out30-113.freemail.mail.aliyun.com (out30-113.freemail.mail.aliyun.com [115.124.30.113]) (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 B2B318F47 for ; Wed, 14 Feb 2024 02:14:47 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=115.124.30.113 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707876890; cv=none; b=HWs+bOkmtQmit31GQrTe9T6W49CwQWdPm+A3xC0gkDfPyN8mTH3LRGpbUGbhqh/3NOucXzZ5QOSxKCQamSa5CA6qXeoPLweNqcbwfg5MBdEx9k4iV6/O0it4bYVIuF/NILyp3MzbXhKxF6/yEs0y5ZEpTv4Xx8YLQOGo60JjRD4= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707876890; c=relaxed/simple; bh=diDjjP0UcH9KCIg7RKOY5kkGKhDvXj0gYGx6d8zMzmw=; h=From:To:Cc:Subject:Date:Message-Id:In-Reply-To:References: MIME-Version; b=OZWwb+EUN8hxcml7Em9L0OZefVxWmR37/AWcFZFP/c+uthkWFG0kw6TIZFV26tPSB5XD+gVd/erJ7UlVy17g6pM286TocjMkhyQyngO63quwTgl/w6f1EqdaFfoeWuXE7s0gbVcvONbrpKG7/Qp2ORbatD4HnRr1S+CeHF9yM0M= 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=PmiaWtRp; arc=none smtp.client-ip=115.124.30.113 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 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.alibaba.com header.i=@linux.alibaba.com header.b="PmiaWtRp" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.alibaba.com; s=default; t=1707876880; h=From:To:Subject:Date:Message-Id:MIME-Version; bh=OydG6x5LqX94qSaZmej/7nHx+rHI5LgOz7Q4udFhjf0=; b=PmiaWtRp6POxd3WgYfEN9BqAk1m6TYRuoXp/u0fce948CNhrFvLk8twGrnjfMiV4EXhrGa+UoYW+KwdgzJm42ab8OqcPVxATnLtyVcZJFaKdbznF28wHOnzFIdpFNzGQcY9Ax4fkdGr4Q91/J+0skQfjYr3irCpAafujOizAtkA= X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R191e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=ay29a033018046051;MF=yaoma@linux.alibaba.com;NM=1;PH=DS;RN=7;SR=0;TI=SMTPD_---0W0b-9GZ_1707876877; Received: from localhost.localdomain(mailfrom:yaoma@linux.alibaba.com fp:SMTPD_---0W0b-9GZ_1707876877) by smtp.aliyun-inc.com; Wed, 14 Feb 2024 10:14:39 +0800 From: Bitao Hu To: dianders@chromium.org, akpm@linux-foundation.org, pmladek@suse.com, kernelfans@gmail.com, liusong@linux.alibaba.com Cc: yaoma@linux.alibaba.com, linux-kernel@vger.kernel.org Subject: [PATCHv7 2/2] watchdog/softlockup: report the most frequent interrupts Date: Wed, 14 Feb 2024 10:14:30 +0800 Message-Id: <20240214021430.87471-3-yaoma@linux.alibaba.com> X-Mailer: git-send-email 2.37.1 (Apple Git-137.1) In-Reply-To: <20240214021430.87471-1-yaoma@linux.alibaba.com> References: <20240214021430.87471-1-yaoma@linux.alibaba.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" When the watchdog determines that the current soft lockup is due to an interrupt storm based on CPU utilization, reporting the most frequent interrupts could be good enough for further troubleshooting. Below is an example of interrupt storm. The call tree does not provide useful information, but we can analyze which interrupt caused the soft lockup by comparing the counts of interrupts. [ 2987.488075] watchdog: BUG: soft lockup - CPU#9 stuck for 23s! [kworker/9= :1:214] [ 2987.488607] CPU#9 Utilization every 4s during lockup: [ 2987.488941] #1: 0% system, 0% softirq, 100% hardirq, 0= % idle [ 2987.489357] #2: 0% system, 0% softirq, 100% hardirq, 0= % idle [ 2987.489771] #3: 0% system, 0% softirq, 100% hardirq, 0= % idle [ 2987.490186] #4: 0% system, 0% softirq, 100% hardirq, 0= % idle [ 2987.490601] #5: 0% system, 0% softirq, 100% hardirq, 0= % idle [ 2987.491034] CPU#9 Detect HardIRQ Time exceeds 50%. Most frequent HardIRQ= s: [ 2987.491493] #1: 330985 irq#7(IPI) [ 2987.491743] #2: 5000 irq#10(arch_timer) [ 2987.492039] #3: 9 irq#91(nvme0q2) [ 2987.492318] #4: 3 irq#118(virtio1-output.12) ... [ 2987.492728] Call trace: [ 2987.492729] __do_softirq+0xa8/0x364 Signed-off-by: Bitao Hu Reviewed-by: Douglas Anderson Reviewed-by: Liu Song --- kernel/watchdog.c | 157 ++++++++++++++++++++++++++++++++++++++++++++-- 1 file changed, 153 insertions(+), 4 deletions(-) diff --git a/kernel/watchdog.c b/kernel/watchdog.c index 69e72d7e461d..0c521b8ae7aa 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -12,22 +12,25 @@ =20 #define pr_fmt(fmt) "watchdog: " fmt =20 -#include #include -#include #include +#include +#include #include +#include #include +#include #include +#include +#include #include #include + #include #include #include -#include =20 #include -#include =20 static DEFINE_MUTEX(watchdog_mutex); =20 @@ -417,13 +420,146 @@ static void print_cpustat(void) } } =20 +#define HARDIRQ_PERCENT_THRESH 50 +#define NUM_HARDIRQ_REPORT 5 +static DEFINE_PER_CPU(u32 *, hardirq_counts); +static DEFINE_PER_CPU(int, actual_nr_irqs); +struct irq_counts { + int irq; + u32 counts; +}; + +/* Tabulate the most frequent interrupts. */ +static void tabulate_irq_count(struct irq_counts *irq_counts, int irq, u32= counts, int rank) +{ + int i; + struct irq_counts new_count =3D {irq, counts}; + + for (i =3D 0; i < rank; i++) { + if (counts > irq_counts[i].counts) + swap(new_count, irq_counts[i]); + } +} + +/* + * If the hardirq time exceeds HARDIRQ_PERCENT_THRESH% of the sample_perio= d, + * then the cause of softlockup might be interrupt storm. In this case, it + * would be useful to start interrupt counting. + */ +static bool need_counting_irqs(void) +{ + u8 util; + int tail =3D __this_cpu_read(cpustat_tail); + + tail =3D (tail + NUM_HARDIRQ_REPORT - 1) % NUM_HARDIRQ_REPORT; + util =3D __this_cpu_read(cpustat_util[tail][STATS_HARDIRQ]); + return util > HARDIRQ_PERCENT_THRESH; +} + +static void start_counting_irqs(void) +{ + int i; + int local_nr_irqs; + struct irq_desc *desc; + u32 *counts =3D __this_cpu_read(hardirq_counts); + + if (!counts) { + /* + * nr_irqs has the potential to grow at runtime. We should read + * it and store locally to avoid array out-of-bounds access. + */ + local_nr_irqs =3D nr_irqs; + counts =3D kcalloc(local_nr_irqs, sizeof(u32), GFP_ATOMIC); + if (!counts) + return; + + for (i =3D 0; i < local_nr_irqs; i++) { + desc =3D irq_to_desc(i); + if (!desc) + continue; + counts[i] =3D desc->kstat_irqs ? + *this_cpu_ptr(desc->kstat_irqs) : 0; + } + + __this_cpu_write(actual_nr_irqs, local_nr_irqs); + __this_cpu_write(hardirq_counts, counts); + } +} + +static void stop_counting_irqs(void) +{ + kfree(__this_cpu_read(hardirq_counts)); + __this_cpu_write(hardirq_counts, NULL); +} + +static void print_irq_counts(void) +{ + int i; + struct irq_desc *desc; + u32 counts_diff; + int local_nr_irqs =3D __this_cpu_read(actual_nr_irqs); + u32 *counts =3D __this_cpu_read(hardirq_counts); + struct irq_counts irq_counts_sorted[NUM_HARDIRQ_REPORT] =3D { + {-1, 0}, {-1, 0}, {-1, 0}, {-1, 0}, + }; + + if (counts) { + for_each_irq_desc(i, desc) { + /* + * We need to bounds-check in case someone on a different CPU + * expanded nr_irqs. + */ + if (desc->kstat_irqs) { + counts_diff =3D *this_cpu_ptr(desc->kstat_irqs); + if (i < local_nr_irqs) + counts_diff -=3D counts[i]; + tabulate_irq_count(irq_counts_sorted, i, counts_diff, + NUM_HARDIRQ_REPORT); + } + } + + /* + * We do not want the "watchdog: " prefix on every line, + * hence we use "printk" instead of "pr_crit". + */ + printk(KERN_CRIT "CPU#%d Detect HardIRQ Time exceeds %d%%. Most frequent= HardIRQs:\n", + smp_processor_id(), HARDIRQ_PERCENT_THRESH); + + for (i =3D 0; i < NUM_HARDIRQ_REPORT; i++) { + if (irq_counts_sorted[i].irq =3D=3D -1) + break; + + desc =3D irq_to_desc(irq_counts_sorted[i].irq); + if (desc && desc->action) + printk(KERN_CRIT "\t#%u: %-10u\tirq#%d(%s)\n", + i + 1, irq_counts_sorted[i].counts, + irq_counts_sorted[i].irq, desc->action->name); + else + printk(KERN_CRIT "\t#%u: %-10u\tirq#%d\n", + i + 1, irq_counts_sorted[i].counts, + irq_counts_sorted[i].irq); + } + + /* + * If the hardirq time is less than HARDIRQ_PERCENT_THRESH% in the last + * sample_period, then we suspect the interrupt storm might be subsiding. + */ + if (!need_counting_irqs()) + stop_counting_irqs(); + } +} + static void report_cpu_status(void) { print_cpustat(); + print_irq_counts(); } #else static inline void update_cpustat(void) { } static inline void report_cpu_status(void) { } +static inline bool need_counting_irqs(void) { return false; } +static inline void start_counting_irqs(void) { } +static inline void stop_counting_irqs(void) { } #endif =20 /* @@ -527,6 +663,18 @@ static int is_softlockup(unsigned long touch_ts, unsigned long now) { if ((watchdog_enabled & WATCHDOG_SOFTOCKUP_ENABLED) && watchdog_thresh) { + /* + * If period_ts has not been updated during a sample_period, then + * in the subsequent few sample_periods, period_ts might also not + * be updated, which could indicate a potential softlockup. In + * this case, if we suspect the cause of the potential softlockup + * might be interrupt storm, then we need to count the interrupts + * to find which interrupt is storming. + */ + if (time_after_eq(now, period_ts + get_softlockup_thresh() / 5) && + need_counting_irqs()) + start_counting_irqs(); + /* Warn about unreasonable delays. */ if (time_after(now, period_ts + get_softlockup_thresh())) return now - touch_ts; @@ -549,6 +697,7 @@ static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_= stop_work); static int softlockup_fn(void *data) { update_touch_ts(); + stop_counting_irqs(); complete(this_cpu_ptr(&softlockup_completion)); =20 return 0; --=20 2.37.1 (Apple Git-137.1)