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![Petr Mladek](/assets/img/avatar_default.png)
The softlockup detector currently shows the time spent since the last report. As a result it is not clear whether a CPU is infinitely hogged by a single task or if it is a repeated event. The situation can be simulated with a simply busy loop: while (true) cpu_relax(); The softlockup detector produces: [ 168.277520] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865] [ 196.277604] watchdog: BUG: soft lockup - CPU#1 stuck for 22s! [cat:4865] [ 236.277522] watchdog: BUG: soft lockup - CPU#1 stuck for 23s! [cat:4865] But it should be, something like: [ 480.372418] watchdog: BUG: soft lockup - CPU#2 stuck for 26s! [cat:4943] [ 508.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 52s! [cat:4943] [ 548.372359] watchdog: BUG: soft lockup - CPU#2 stuck for 89s! [cat:4943] [ 576.372351] watchdog: BUG: soft lockup - CPU#2 stuck for 115s! [cat:4943] For the better output, add an additional timestamp of the last report. Only this timestamp is reset when the watchdog is intentionally touched from slow code paths or when printing the report. Link: https://lkml.kernel.org/r/20210311122130.6788-4-pmladek@suse.com Signed-off-by: Petr Mladek <pmladek@suse.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Laurence Oberman <loberman@redhat.com> Cc: Michal Hocko <mhocko@suse.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Vincent Whitchurch <vincent.whitchurch@axis.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
773 lines
21 KiB
C
773 lines
21 KiB
C
// SPDX-License-Identifier: GPL-2.0
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/*
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* Detect hard and soft lockups on a system
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*
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* started by Don Zickus, Copyright (C) 2010 Red Hat, Inc.
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*
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* Note: Most of this code is borrowed heavily from the original softlockup
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* detector, so thanks to Ingo for the initial implementation.
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* Some chunks also taken from the old x86-specific nmi watchdog code, thanks
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* to those contributors as well.
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*/
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#define pr_fmt(fmt) "watchdog: " fmt
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#include <linux/mm.h>
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#include <linux/cpu.h>
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#include <linux/nmi.h>
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#include <linux/init.h>
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#include <linux/module.h>
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#include <linux/sysctl.h>
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#include <linux/tick.h>
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#include <linux/sched/clock.h>
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#include <linux/sched/debug.h>
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#include <linux/sched/isolation.h>
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#include <linux/stop_machine.h>
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#include <asm/irq_regs.h>
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#include <linux/kvm_para.h>
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static DEFINE_MUTEX(watchdog_mutex);
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#if defined(CONFIG_HARDLOCKUP_DETECTOR) || defined(CONFIG_HAVE_NMI_WATCHDOG)
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# define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED | NMI_WATCHDOG_ENABLED)
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# define NMI_WATCHDOG_DEFAULT 1
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#else
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# define WATCHDOG_DEFAULT (SOFT_WATCHDOG_ENABLED)
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# define NMI_WATCHDOG_DEFAULT 0
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#endif
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unsigned long __read_mostly watchdog_enabled;
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int __read_mostly watchdog_user_enabled = 1;
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int __read_mostly nmi_watchdog_user_enabled = NMI_WATCHDOG_DEFAULT;
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int __read_mostly soft_watchdog_user_enabled = 1;
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int __read_mostly watchdog_thresh = 10;
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static int __read_mostly nmi_watchdog_available;
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struct cpumask watchdog_cpumask __read_mostly;
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unsigned long *watchdog_cpumask_bits = cpumask_bits(&watchdog_cpumask);
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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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# ifdef CONFIG_SMP
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int __read_mostly sysctl_hardlockup_all_cpu_backtrace;
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# endif /* CONFIG_SMP */
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/*
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* Should we panic when a soft-lockup or hard-lockup occurs:
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*/
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unsigned int __read_mostly hardlockup_panic =
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CONFIG_BOOTPARAM_HARDLOCKUP_PANIC_VALUE;
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/*
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* We may not want to enable hard lockup detection by default in all cases,
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* for example when running the kernel as a guest on a hypervisor. In these
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* cases this function can be called to disable hard lockup detection. This
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* function should only be executed once by the boot processor before the
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* kernel command line parameters are parsed, because otherwise it is not
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* possible to override this in hardlockup_panic_setup().
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*/
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void __init hardlockup_detector_disable(void)
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{
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nmi_watchdog_user_enabled = 0;
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}
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static int __init hardlockup_panic_setup(char *str)
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{
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if (!strncmp(str, "panic", 5))
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hardlockup_panic = 1;
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else if (!strncmp(str, "nopanic", 7))
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hardlockup_panic = 0;
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else if (!strncmp(str, "0", 1))
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nmi_watchdog_user_enabled = 0;
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else if (!strncmp(str, "1", 1))
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nmi_watchdog_user_enabled = 1;
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return 1;
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}
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__setup("nmi_watchdog=", hardlockup_panic_setup);
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#endif /* CONFIG_HARDLOCKUP_DETECTOR */
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/*
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* These functions can be overridden if an architecture implements its
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* own hardlockup detector.
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*
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* watchdog_nmi_enable/disable can be implemented to start and stop when
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* softlockup watchdog threads start and stop. The arch must select the
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* SOFTLOCKUP_DETECTOR Kconfig.
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*/
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int __weak watchdog_nmi_enable(unsigned int cpu)
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{
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hardlockup_detector_perf_enable();
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return 0;
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}
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void __weak watchdog_nmi_disable(unsigned int cpu)
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{
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hardlockup_detector_perf_disable();
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}
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/* Return 0, if a NMI watchdog is available. Error code otherwise */
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int __weak __init watchdog_nmi_probe(void)
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{
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return hardlockup_detector_perf_init();
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}
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/**
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* watchdog_nmi_stop - Stop the watchdog for reconfiguration
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*
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* The reconfiguration steps are:
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* watchdog_nmi_stop();
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* update_variables();
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* watchdog_nmi_start();
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*/
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void __weak watchdog_nmi_stop(void) { }
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/**
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* watchdog_nmi_start - Start the watchdog after reconfiguration
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*
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* Counterpart to watchdog_nmi_stop().
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*
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* The following variables have been updated in update_variables() and
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* contain the currently valid configuration:
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* - watchdog_enabled
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* - watchdog_thresh
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* - watchdog_cpumask
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*/
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void __weak watchdog_nmi_start(void) { }
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/**
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* lockup_detector_update_enable - Update the sysctl enable bit
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*
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* Caller needs to make sure that the NMI/perf watchdogs are off, so this
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* can't race with watchdog_nmi_disable().
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*/
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static void lockup_detector_update_enable(void)
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{
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watchdog_enabled = 0;
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if (!watchdog_user_enabled)
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return;
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if (nmi_watchdog_available && nmi_watchdog_user_enabled)
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watchdog_enabled |= NMI_WATCHDOG_ENABLED;
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if (soft_watchdog_user_enabled)
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watchdog_enabled |= SOFT_WATCHDOG_ENABLED;
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}
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#ifdef CONFIG_SOFTLOCKUP_DETECTOR
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/*
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* Delay the soflockup report when running a known slow code.
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* It does _not_ affect the timestamp of the last successdul reschedule.
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*/
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#define SOFTLOCKUP_DELAY_REPORT ULONG_MAX
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#ifdef CONFIG_SMP
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int __read_mostly sysctl_softlockup_all_cpu_backtrace;
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#endif
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static struct cpumask watchdog_allowed_mask __read_mostly;
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/* Global variables, exported for sysctl */
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unsigned int __read_mostly softlockup_panic =
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CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
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static bool softlockup_initialized __read_mostly;
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static u64 __read_mostly sample_period;
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/* Timestamp taken after the last successful reschedule. */
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static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
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/* Timestamp of the last softlockup report. */
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static DEFINE_PER_CPU(unsigned long, watchdog_report_ts);
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static DEFINE_PER_CPU(struct hrtimer, watchdog_hrtimer);
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static DEFINE_PER_CPU(bool, softlockup_touch_sync);
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static DEFINE_PER_CPU(bool, soft_watchdog_warn);
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static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts);
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static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved);
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static unsigned long soft_lockup_nmi_warn;
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static int __init nowatchdog_setup(char *str)
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{
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watchdog_user_enabled = 0;
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return 1;
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}
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__setup("nowatchdog", nowatchdog_setup);
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static int __init nosoftlockup_setup(char *str)
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{
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soft_watchdog_user_enabled = 0;
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return 1;
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}
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__setup("nosoftlockup", nosoftlockup_setup);
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static int __init watchdog_thresh_setup(char *str)
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{
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get_option(&str, &watchdog_thresh);
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return 1;
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}
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__setup("watchdog_thresh=", watchdog_thresh_setup);
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static void __lockup_detector_cleanup(void);
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/*
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* Hard-lockup warnings should be triggered after just a few seconds. Soft-
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* lockups can have false positives under extreme conditions. So we generally
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* want a higher threshold for soft lockups than for hard lockups. So we couple
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* the thresholds with a factor: we make the soft threshold twice the amount of
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* time the hard threshold is.
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*/
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static int get_softlockup_thresh(void)
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{
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return watchdog_thresh * 2;
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}
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/*
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* Returns seconds, approximately. We don't need nanosecond
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* resolution, and we don't need to waste time with a big divide when
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* 2^30ns == 1.074s.
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*/
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static unsigned long get_timestamp(void)
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{
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return running_clock() >> 30LL; /* 2^30 ~= 10^9 */
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}
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static void set_sample_period(void)
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{
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/*
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* convert watchdog_thresh from seconds to ns
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* the divide by 5 is to give hrtimer several chances (two
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* or three with the current relation between the soft
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* and hard thresholds) to increment before the
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* hardlockup detector generates a warning
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*/
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sample_period = get_softlockup_thresh() * ((u64)NSEC_PER_SEC / 5);
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watchdog_update_hrtimer_threshold(sample_period);
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}
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static void update_report_ts(void)
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{
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__this_cpu_write(watchdog_report_ts, get_timestamp());
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}
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/* Commands for resetting the watchdog */
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static void update_touch_ts(void)
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{
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__this_cpu_write(watchdog_touch_ts, get_timestamp());
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update_report_ts();
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}
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/**
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* touch_softlockup_watchdog_sched - touch watchdog on scheduler stalls
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*
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* Call when the scheduler may have stalled for legitimate reasons
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* preventing the watchdog task from executing - e.g. the scheduler
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* entering idle state. This should only be used for scheduler events.
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* Use touch_softlockup_watchdog() for everything else.
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*/
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notrace void touch_softlockup_watchdog_sched(void)
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{
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/*
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* Preemption can be enabled. It doesn't matter which CPU's watchdog
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* report period gets restarted here, so use the raw_ operation.
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*/
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raw_cpu_write(watchdog_report_ts, SOFTLOCKUP_DELAY_REPORT);
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}
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notrace void touch_softlockup_watchdog(void)
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{
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touch_softlockup_watchdog_sched();
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wq_watchdog_touch(raw_smp_processor_id());
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}
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EXPORT_SYMBOL(touch_softlockup_watchdog);
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void touch_all_softlockup_watchdogs(void)
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{
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int cpu;
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/*
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* watchdog_mutex cannpt be taken here, as this might be called
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* from (soft)interrupt context, so the access to
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* watchdog_allowed_cpumask might race with a concurrent update.
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*
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* The watchdog time stamp can race against a concurrent real
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* update as well, the only side effect might be a cycle delay for
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* the softlockup check.
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*/
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for_each_cpu(cpu, &watchdog_allowed_mask) {
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per_cpu(watchdog_report_ts, cpu) = SOFTLOCKUP_DELAY_REPORT;
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wq_watchdog_touch(cpu);
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}
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}
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void touch_softlockup_watchdog_sync(void)
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{
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__this_cpu_write(softlockup_touch_sync, true);
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__this_cpu_write(watchdog_report_ts, SOFTLOCKUP_DELAY_REPORT);
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}
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static int is_softlockup(unsigned long touch_ts, unsigned long period_ts)
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{
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unsigned long now = get_timestamp();
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if ((watchdog_enabled & SOFT_WATCHDOG_ENABLED) && watchdog_thresh){
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/* Warn about unreasonable delays. */
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if (time_after(now, period_ts + get_softlockup_thresh()))
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return now - touch_ts;
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}
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return 0;
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}
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/* watchdog detector functions */
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bool is_hardlockup(void)
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{
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unsigned long hrint = __this_cpu_read(hrtimer_interrupts);
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if (__this_cpu_read(hrtimer_interrupts_saved) == hrint)
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return true;
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__this_cpu_write(hrtimer_interrupts_saved, hrint);
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return false;
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}
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static void watchdog_interrupt_count(void)
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{
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__this_cpu_inc(hrtimer_interrupts);
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}
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static DEFINE_PER_CPU(struct completion, softlockup_completion);
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static DEFINE_PER_CPU(struct cpu_stop_work, softlockup_stop_work);
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/*
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* The watchdog thread function - touches the timestamp.
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*
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* It only runs once every sample_period seconds (4 seconds by
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* default) to reset the softlockup timestamp. If this gets delayed
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* for more than 2*watchdog_thresh seconds then the debug-printout
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* triggers in watchdog_timer_fn().
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*/
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static int softlockup_fn(void *data)
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{
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update_touch_ts();
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complete(this_cpu_ptr(&softlockup_completion));
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return 0;
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}
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/* watchdog kicker functions */
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static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer)
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{
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unsigned long touch_ts = __this_cpu_read(watchdog_touch_ts);
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unsigned long period_ts = __this_cpu_read(watchdog_report_ts);
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struct pt_regs *regs = get_irq_regs();
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int duration;
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int softlockup_all_cpu_backtrace = sysctl_softlockup_all_cpu_backtrace;
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if (!watchdog_enabled)
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return HRTIMER_NORESTART;
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/* kick the hardlockup detector */
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watchdog_interrupt_count();
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/* kick the softlockup detector */
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if (completion_done(this_cpu_ptr(&softlockup_completion))) {
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reinit_completion(this_cpu_ptr(&softlockup_completion));
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stop_one_cpu_nowait(smp_processor_id(),
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softlockup_fn, NULL,
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this_cpu_ptr(&softlockup_stop_work));
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}
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/* .. and repeat */
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hrtimer_forward_now(hrtimer, ns_to_ktime(sample_period));
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/* Reset the interval when touched externally by a known slow code. */
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if (period_ts == SOFTLOCKUP_DELAY_REPORT) {
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if (unlikely(__this_cpu_read(softlockup_touch_sync))) {
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/*
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* If the time stamp was touched atomically
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* make sure the scheduler tick is up to date.
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*/
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__this_cpu_write(softlockup_touch_sync, false);
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sched_clock_tick();
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}
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/* Clear the guest paused flag on watchdog reset */
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kvm_check_and_clear_guest_paused();
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update_report_ts();
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return HRTIMER_RESTART;
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}
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/* check for a softlockup
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* This is done by making sure a high priority task is
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* being scheduled. The task touches the watchdog to
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* indicate it is getting cpu time. If it hasn't then
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* this is a good indication some task is hogging the cpu
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*/
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duration = is_softlockup(touch_ts, period_ts);
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if (unlikely(duration)) {
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/*
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* If a virtual machine is stopped by the host it can look to
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* the watchdog like a soft lockup, check to see if the host
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* stopped the vm before we issue the warning
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*/
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if (kvm_check_and_clear_guest_paused())
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return HRTIMER_RESTART;
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/* only warn once */
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if (__this_cpu_read(soft_watchdog_warn) == true)
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return HRTIMER_RESTART;
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if (softlockup_all_cpu_backtrace) {
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/* Prevent multiple soft-lockup reports if one cpu is already
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* engaged in dumping cpu back traces
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*/
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if (test_and_set_bit(0, &soft_lockup_nmi_warn)) {
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/* Someone else will report us. Let's give up */
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__this_cpu_write(soft_watchdog_warn, true);
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return HRTIMER_RESTART;
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}
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}
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/* Start period for the next softlockup warning. */
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update_report_ts();
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pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n",
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smp_processor_id(), duration,
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current->comm, task_pid_nr(current));
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print_modules();
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print_irqtrace_events(current);
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if (regs)
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show_regs(regs);
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else
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dump_stack();
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if (softlockup_all_cpu_backtrace) {
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/* Avoid generating two back traces for current
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* given that one is already made above
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*/
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trigger_allbutself_cpu_backtrace();
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clear_bit(0, &soft_lockup_nmi_warn);
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/* Barrier to sync with other cpus */
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smp_mb__after_atomic();
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}
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add_taint(TAINT_SOFTLOCKUP, LOCKDEP_STILL_OK);
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if (softlockup_panic)
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panic("softlockup: hung tasks");
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__this_cpu_write(soft_watchdog_warn, true);
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} else
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__this_cpu_write(soft_watchdog_warn, false);
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return HRTIMER_RESTART;
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}
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static void watchdog_enable(unsigned int cpu)
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{
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struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
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struct completion *done = this_cpu_ptr(&softlockup_completion);
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WARN_ON_ONCE(cpu != smp_processor_id());
|
|
|
|
init_completion(done);
|
|
complete(done);
|
|
|
|
/*
|
|
* Start the timer first to prevent the NMI watchdog triggering
|
|
* before the timer has a chance to fire.
|
|
*/
|
|
hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL_HARD);
|
|
hrtimer->function = watchdog_timer_fn;
|
|
hrtimer_start(hrtimer, ns_to_ktime(sample_period),
|
|
HRTIMER_MODE_REL_PINNED_HARD);
|
|
|
|
/* Initialize timestamp */
|
|
update_touch_ts();
|
|
/* Enable the perf event */
|
|
if (watchdog_enabled & NMI_WATCHDOG_ENABLED)
|
|
watchdog_nmi_enable(cpu);
|
|
}
|
|
|
|
static void watchdog_disable(unsigned int cpu)
|
|
{
|
|
struct hrtimer *hrtimer = this_cpu_ptr(&watchdog_hrtimer);
|
|
|
|
WARN_ON_ONCE(cpu != smp_processor_id());
|
|
|
|
/*
|
|
* Disable the perf event first. That prevents that a large delay
|
|
* between disabling the timer and disabling the perf event causes
|
|
* the perf NMI to detect a false positive.
|
|
*/
|
|
watchdog_nmi_disable(cpu);
|
|
hrtimer_cancel(hrtimer);
|
|
wait_for_completion(this_cpu_ptr(&softlockup_completion));
|
|
}
|
|
|
|
static int softlockup_stop_fn(void *data)
|
|
{
|
|
watchdog_disable(smp_processor_id());
|
|
return 0;
|
|
}
|
|
|
|
static void softlockup_stop_all(void)
|
|
{
|
|
int cpu;
|
|
|
|
if (!softlockup_initialized)
|
|
return;
|
|
|
|
for_each_cpu(cpu, &watchdog_allowed_mask)
|
|
smp_call_on_cpu(cpu, softlockup_stop_fn, NULL, false);
|
|
|
|
cpumask_clear(&watchdog_allowed_mask);
|
|
}
|
|
|
|
static int softlockup_start_fn(void *data)
|
|
{
|
|
watchdog_enable(smp_processor_id());
|
|
return 0;
|
|
}
|
|
|
|
static void softlockup_start_all(void)
|
|
{
|
|
int cpu;
|
|
|
|
cpumask_copy(&watchdog_allowed_mask, &watchdog_cpumask);
|
|
for_each_cpu(cpu, &watchdog_allowed_mask)
|
|
smp_call_on_cpu(cpu, softlockup_start_fn, NULL, false);
|
|
}
|
|
|
|
int lockup_detector_online_cpu(unsigned int cpu)
|
|
{
|
|
if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
|
|
watchdog_enable(cpu);
|
|
return 0;
|
|
}
|
|
|
|
int lockup_detector_offline_cpu(unsigned int cpu)
|
|
{
|
|
if (cpumask_test_cpu(cpu, &watchdog_allowed_mask))
|
|
watchdog_disable(cpu);
|
|
return 0;
|
|
}
|
|
|
|
static void lockup_detector_reconfigure(void)
|
|
{
|
|
cpus_read_lock();
|
|
watchdog_nmi_stop();
|
|
|
|
softlockup_stop_all();
|
|
set_sample_period();
|
|
lockup_detector_update_enable();
|
|
if (watchdog_enabled && watchdog_thresh)
|
|
softlockup_start_all();
|
|
|
|
watchdog_nmi_start();
|
|
cpus_read_unlock();
|
|
/*
|
|
* Must be called outside the cpus locked section to prevent
|
|
* recursive locking in the perf code.
|
|
*/
|
|
__lockup_detector_cleanup();
|
|
}
|
|
|
|
/*
|
|
* Create the watchdog thread infrastructure and configure the detector(s).
|
|
*
|
|
* The threads are not unparked as watchdog_allowed_mask is empty. When
|
|
* the threads are successfully initialized, take the proper locks and
|
|
* unpark the threads in the watchdog_cpumask if the watchdog is enabled.
|
|
*/
|
|
static __init void lockup_detector_setup(void)
|
|
{
|
|
/*
|
|
* If sysctl is off and watchdog got disabled on the command line,
|
|
* nothing to do here.
|
|
*/
|
|
lockup_detector_update_enable();
|
|
|
|
if (!IS_ENABLED(CONFIG_SYSCTL) &&
|
|
!(watchdog_enabled && watchdog_thresh))
|
|
return;
|
|
|
|
mutex_lock(&watchdog_mutex);
|
|
lockup_detector_reconfigure();
|
|
softlockup_initialized = true;
|
|
mutex_unlock(&watchdog_mutex);
|
|
}
|
|
|
|
#else /* CONFIG_SOFTLOCKUP_DETECTOR */
|
|
static void lockup_detector_reconfigure(void)
|
|
{
|
|
cpus_read_lock();
|
|
watchdog_nmi_stop();
|
|
lockup_detector_update_enable();
|
|
watchdog_nmi_start();
|
|
cpus_read_unlock();
|
|
}
|
|
static inline void lockup_detector_setup(void)
|
|
{
|
|
lockup_detector_reconfigure();
|
|
}
|
|
#endif /* !CONFIG_SOFTLOCKUP_DETECTOR */
|
|
|
|
static void __lockup_detector_cleanup(void)
|
|
{
|
|
lockdep_assert_held(&watchdog_mutex);
|
|
hardlockup_detector_perf_cleanup();
|
|
}
|
|
|
|
/**
|
|
* lockup_detector_cleanup - Cleanup after cpu hotplug or sysctl changes
|
|
*
|
|
* Caller must not hold the cpu hotplug rwsem.
|
|
*/
|
|
void lockup_detector_cleanup(void)
|
|
{
|
|
mutex_lock(&watchdog_mutex);
|
|
__lockup_detector_cleanup();
|
|
mutex_unlock(&watchdog_mutex);
|
|
}
|
|
|
|
/**
|
|
* lockup_detector_soft_poweroff - Interface to stop lockup detector(s)
|
|
*
|
|
* Special interface for parisc. It prevents lockup detector warnings from
|
|
* the default pm_poweroff() function which busy loops forever.
|
|
*/
|
|
void lockup_detector_soft_poweroff(void)
|
|
{
|
|
watchdog_enabled = 0;
|
|
}
|
|
|
|
#ifdef CONFIG_SYSCTL
|
|
|
|
/* Propagate any changes to the watchdog threads */
|
|
static void proc_watchdog_update(void)
|
|
{
|
|
/* Remove impossible cpus to keep sysctl output clean. */
|
|
cpumask_and(&watchdog_cpumask, &watchdog_cpumask, cpu_possible_mask);
|
|
lockup_detector_reconfigure();
|
|
}
|
|
|
|
/*
|
|
* common function for watchdog, nmi_watchdog and soft_watchdog parameter
|
|
*
|
|
* caller | table->data points to | 'which'
|
|
* -------------------|----------------------------|--------------------------
|
|
* proc_watchdog | watchdog_user_enabled | NMI_WATCHDOG_ENABLED |
|
|
* | | SOFT_WATCHDOG_ENABLED
|
|
* -------------------|----------------------------|--------------------------
|
|
* proc_nmi_watchdog | nmi_watchdog_user_enabled | NMI_WATCHDOG_ENABLED
|
|
* -------------------|----------------------------|--------------------------
|
|
* proc_soft_watchdog | soft_watchdog_user_enabled | SOFT_WATCHDOG_ENABLED
|
|
*/
|
|
static int proc_watchdog_common(int which, struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
int err, old, *param = table->data;
|
|
|
|
mutex_lock(&watchdog_mutex);
|
|
|
|
if (!write) {
|
|
/*
|
|
* On read synchronize the userspace interface. This is a
|
|
* racy snapshot.
|
|
*/
|
|
*param = (watchdog_enabled & which) != 0;
|
|
err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
} else {
|
|
old = READ_ONCE(*param);
|
|
err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
if (!err && old != READ_ONCE(*param))
|
|
proc_watchdog_update();
|
|
}
|
|
mutex_unlock(&watchdog_mutex);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* /proc/sys/kernel/watchdog
|
|
*/
|
|
int proc_watchdog(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
return proc_watchdog_common(NMI_WATCHDOG_ENABLED|SOFT_WATCHDOG_ENABLED,
|
|
table, write, buffer, lenp, ppos);
|
|
}
|
|
|
|
/*
|
|
* /proc/sys/kernel/nmi_watchdog
|
|
*/
|
|
int proc_nmi_watchdog(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
if (!nmi_watchdog_available && write)
|
|
return -ENOTSUPP;
|
|
return proc_watchdog_common(NMI_WATCHDOG_ENABLED,
|
|
table, write, buffer, lenp, ppos);
|
|
}
|
|
|
|
/*
|
|
* /proc/sys/kernel/soft_watchdog
|
|
*/
|
|
int proc_soft_watchdog(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
return proc_watchdog_common(SOFT_WATCHDOG_ENABLED,
|
|
table, write, buffer, lenp, ppos);
|
|
}
|
|
|
|
/*
|
|
* /proc/sys/kernel/watchdog_thresh
|
|
*/
|
|
int proc_watchdog_thresh(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
int err, old;
|
|
|
|
mutex_lock(&watchdog_mutex);
|
|
|
|
old = READ_ONCE(watchdog_thresh);
|
|
err = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
|
|
if (!err && write && old != READ_ONCE(watchdog_thresh))
|
|
proc_watchdog_update();
|
|
|
|
mutex_unlock(&watchdog_mutex);
|
|
return err;
|
|
}
|
|
|
|
/*
|
|
* The cpumask is the mask of possible cpus that the watchdog can run
|
|
* on, not the mask of cpus it is actually running on. This allows the
|
|
* user to specify a mask that will include cpus that have not yet
|
|
* been brought online, if desired.
|
|
*/
|
|
int proc_watchdog_cpumask(struct ctl_table *table, int write,
|
|
void *buffer, size_t *lenp, loff_t *ppos)
|
|
{
|
|
int err;
|
|
|
|
mutex_lock(&watchdog_mutex);
|
|
|
|
err = proc_do_large_bitmap(table, write, buffer, lenp, ppos);
|
|
if (!err && write)
|
|
proc_watchdog_update();
|
|
|
|
mutex_unlock(&watchdog_mutex);
|
|
return err;
|
|
}
|
|
#endif /* CONFIG_SYSCTL */
|
|
|
|
void __init lockup_detector_init(void)
|
|
{
|
|
if (tick_nohz_full_enabled())
|
|
pr_info("Disabling watchdog on nohz_full cores by default\n");
|
|
|
|
cpumask_copy(&watchdog_cpumask,
|
|
housekeeping_cpumask(HK_FLAG_TIMER));
|
|
|
|
if (!watchdog_nmi_probe())
|
|
nmi_watchdog_available = true;
|
|
lockup_detector_setup();
|
|
}
|