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https://github.com/AuxXxilium/linux_dsm_epyc7002.git
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72eb6a7914
* 'for-2.6.38' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/percpu: (30 commits) gameport: use this_cpu_read instead of lookup x86: udelay: Use this_cpu_read to avoid address calculation x86: Use this_cpu_inc_return for nmi counter x86: Replace uses of current_cpu_data with this_cpu ops x86: Use this_cpu_ops to optimize code vmstat: User per cpu atomics to avoid interrupt disable / enable irq_work: Use per cpu atomics instead of regular atomics cpuops: Use cmpxchg for xchg to avoid lock semantics x86: this_cpu_cmpxchg and this_cpu_xchg operations percpu: Generic this_cpu_cmpxchg() and this_cpu_xchg support percpu,x86: relocate this_cpu_add_return() and friends connector: Use this_cpu operations xen: Use this_cpu_inc_return taskstats: Use this_cpu_ops random: Use this_cpu_inc_return fs: Use this_cpu_inc_return in buffer.c highmem: Use this_cpu_xx_return() operations vmstat: Use this_cpu_inc_return for vm statistics x86: Support for this_cpu_add, sub, dec, inc_return percpu: Generic support for this_cpu_add, sub, dec, inc_return ... Fixed up conflicts: in arch/x86/kernel/{apic/nmi.c, apic/x2apic_uv_x.c, process.c} as per Tejun.
569 lines
13 KiB
C
569 lines
13 KiB
C
/*
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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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* this code detects hard lockups: incidents in where on a CPU
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* the kernel does not respond to anything except NMI.
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*
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* Note: Most of this code is borrowed heavily from softlockup.c,
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* so thanks to Ingo for the initial implementation.
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* Some chunks also taken from arch/x86/kernel/apic/nmi.c, thanks
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* to those contributors as well.
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*/
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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/delay.h>
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#include <linux/freezer.h>
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#include <linux/kthread.h>
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#include <linux/lockdep.h>
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#include <linux/notifier.h>
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#include <linux/module.h>
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#include <linux/sysctl.h>
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#include <asm/irq_regs.h>
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#include <linux/perf_event.h>
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int watchdog_enabled;
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int __read_mostly softlockup_thresh = 60;
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static DEFINE_PER_CPU(unsigned long, watchdog_touch_ts);
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static DEFINE_PER_CPU(struct task_struct *, softlockup_watchdog);
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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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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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static DEFINE_PER_CPU(bool, hard_watchdog_warn);
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static DEFINE_PER_CPU(bool, watchdog_nmi_touch);
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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 DEFINE_PER_CPU(struct perf_event *, watchdog_ev);
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#endif
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static int no_watchdog;
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/* boot commands */
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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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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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static int hardlockup_panic;
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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, "0", 1))
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no_watchdog = 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
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unsigned int __read_mostly softlockup_panic =
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CONFIG_BOOTPARAM_SOFTLOCKUP_PANIC_VALUE;
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static int __init softlockup_panic_setup(char *str)
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{
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softlockup_panic = simple_strtoul(str, NULL, 0);
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return 1;
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}
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__setup("softlockup_panic=", softlockup_panic_setup);
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static int __init nowatchdog_setup(char *str)
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{
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no_watchdog = 1;
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return 1;
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}
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__setup("nowatchdog", nowatchdog_setup);
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/* deprecated */
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static int __init nosoftlockup_setup(char *str)
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{
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no_watchdog = 1;
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return 1;
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}
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__setup("nosoftlockup", nosoftlockup_setup);
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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(int this_cpu)
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{
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return cpu_clock(this_cpu) >> 30LL; /* 2^30 ~= 10^9 */
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}
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static unsigned long get_sample_period(void)
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{
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/*
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* convert softlockup_thresh from seconds to ns
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* the divide by 5 is to give hrtimer 5 chances to
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* increment before the hardlockup detector generates
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* a warning
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*/
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return softlockup_thresh / 5 * NSEC_PER_SEC;
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}
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/* Commands for resetting the watchdog */
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static void __touch_watchdog(void)
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{
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int this_cpu = smp_processor_id();
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__this_cpu_write(watchdog_touch_ts, get_timestamp(this_cpu));
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}
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void touch_softlockup_watchdog(void)
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{
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__this_cpu_write(watchdog_touch_ts, 0);
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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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* this is done lockless
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* do we care if a 0 races with a timestamp?
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* all it means is the softlock check starts one cycle later
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*/
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for_each_online_cpu(cpu)
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per_cpu(watchdog_touch_ts, cpu) = 0;
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}
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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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void touch_nmi_watchdog(void)
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{
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if (watchdog_enabled) {
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unsigned cpu;
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for_each_present_cpu(cpu) {
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if (per_cpu(watchdog_nmi_touch, cpu) != true)
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per_cpu(watchdog_nmi_touch, cpu) = true;
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}
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}
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touch_softlockup_watchdog();
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}
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EXPORT_SYMBOL(touch_nmi_watchdog);
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#endif
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void touch_softlockup_watchdog_sync(void)
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{
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__raw_get_cpu_var(softlockup_touch_sync) = true;
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__raw_get_cpu_var(watchdog_touch_ts) = 0;
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}
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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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/* watchdog detector functions */
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static int 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 1;
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__this_cpu_write(hrtimer_interrupts_saved, hrint);
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return 0;
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}
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#endif
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static int is_softlockup(unsigned long touch_ts)
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{
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unsigned long now = get_timestamp(smp_processor_id());
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/* Warn about unreasonable delays: */
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if (time_after(now, touch_ts + softlockup_thresh))
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return now - touch_ts;
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return 0;
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}
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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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static struct perf_event_attr wd_hw_attr = {
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.type = PERF_TYPE_HARDWARE,
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.config = PERF_COUNT_HW_CPU_CYCLES,
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.size = sizeof(struct perf_event_attr),
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.pinned = 1,
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.disabled = 1,
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};
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/* Callback function for perf event subsystem */
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static void watchdog_overflow_callback(struct perf_event *event, int nmi,
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struct perf_sample_data *data,
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struct pt_regs *regs)
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{
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/* Ensure the watchdog never gets throttled */
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event->hw.interrupts = 0;
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if (__this_cpu_read(watchdog_nmi_touch) == true) {
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__this_cpu_write(watchdog_nmi_touch, false);
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return;
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}
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/* check for a hardlockup
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* This is done by making sure our timer interrupt
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* is incrementing. The timer interrupt should have
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* fired multiple times before we overflow'd. If it hasn't
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* then this is a good indication the cpu is stuck
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*/
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if (is_hardlockup()) {
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int this_cpu = smp_processor_id();
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/* only print hardlockups once */
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if (__this_cpu_read(hard_watchdog_warn) == true)
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return;
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if (hardlockup_panic)
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panic("Watchdog detected hard LOCKUP on cpu %d", this_cpu);
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else
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WARN(1, "Watchdog detected hard LOCKUP on cpu %d", this_cpu);
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__this_cpu_write(hard_watchdog_warn, true);
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return;
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}
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__this_cpu_write(hard_watchdog_warn, false);
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return;
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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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#else
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static inline void watchdog_interrupt_count(void) { return; }
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#endif /* CONFIG_HARDLOCKUP_DETECTOR */
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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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struct pt_regs *regs = get_irq_regs();
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int duration;
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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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wake_up_process(__this_cpu_read(softlockup_watchdog));
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/* .. and repeat */
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hrtimer_forward_now(hrtimer, ns_to_ktime(get_sample_period()));
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if (touch_ts == 0) {
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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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__touch_watchdog();
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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);
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if (unlikely(duration)) {
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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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printk(KERN_ERR "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_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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/*
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* The watchdog thread - touches the timestamp.
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*/
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static int watchdog(void *unused)
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{
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static struct sched_param param = { .sched_priority = MAX_RT_PRIO-1 };
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struct hrtimer *hrtimer = &__raw_get_cpu_var(watchdog_hrtimer);
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sched_setscheduler(current, SCHED_FIFO, ¶m);
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/* initialize timestamp */
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__touch_watchdog();
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/* kick off the timer for the hardlockup detector */
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/* done here because hrtimer_start can only pin to smp_processor_id() */
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hrtimer_start(hrtimer, ns_to_ktime(get_sample_period()),
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HRTIMER_MODE_REL_PINNED);
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set_current_state(TASK_INTERRUPTIBLE);
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/*
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* Run briefly once per second to reset the softlockup timestamp.
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* If this gets delayed for more than 60 seconds then the
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* debug-printout triggers in watchdog_timer_fn().
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*/
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while (!kthread_should_stop()) {
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__touch_watchdog();
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schedule();
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if (kthread_should_stop())
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break;
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set_current_state(TASK_INTERRUPTIBLE);
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}
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__set_current_state(TASK_RUNNING);
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return 0;
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}
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#ifdef CONFIG_HARDLOCKUP_DETECTOR
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static int watchdog_nmi_enable(int cpu)
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{
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struct perf_event_attr *wd_attr;
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struct perf_event *event = per_cpu(watchdog_ev, cpu);
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/* is it already setup and enabled? */
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if (event && event->state > PERF_EVENT_STATE_OFF)
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goto out;
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/* it is setup but not enabled */
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if (event != NULL)
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goto out_enable;
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/* Try to register using hardware perf events */
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wd_attr = &wd_hw_attr;
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wd_attr->sample_period = hw_nmi_get_sample_period();
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event = perf_event_create_kernel_counter(wd_attr, cpu, NULL, watchdog_overflow_callback);
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if (!IS_ERR(event)) {
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printk(KERN_INFO "NMI watchdog enabled, takes one hw-pmu counter.\n");
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goto out_save;
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}
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printk(KERN_ERR "NMI watchdog disabled for cpu%i: unable to create perf event: %ld\n",
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cpu, PTR_ERR(event));
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return PTR_ERR(event);
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/* success path */
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out_save:
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per_cpu(watchdog_ev, cpu) = event;
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out_enable:
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perf_event_enable(per_cpu(watchdog_ev, cpu));
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out:
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return 0;
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}
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static void watchdog_nmi_disable(int cpu)
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{
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struct perf_event *event = per_cpu(watchdog_ev, cpu);
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if (event) {
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perf_event_disable(event);
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per_cpu(watchdog_ev, cpu) = NULL;
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/* should be in cleanup, but blocks oprofile */
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perf_event_release_kernel(event);
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}
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return;
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}
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#else
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static int watchdog_nmi_enable(int cpu) { return 0; }
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static void watchdog_nmi_disable(int cpu) { return; }
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#endif /* CONFIG_HARDLOCKUP_DETECTOR */
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/* prepare/enable/disable routines */
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static int watchdog_prepare_cpu(int cpu)
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{
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struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
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WARN_ON(per_cpu(softlockup_watchdog, cpu));
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hrtimer_init(hrtimer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
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hrtimer->function = watchdog_timer_fn;
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return 0;
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}
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static int watchdog_enable(int cpu)
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{
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struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
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int err;
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/* enable the perf event */
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err = watchdog_nmi_enable(cpu);
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if (err)
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return err;
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/* create the watchdog thread */
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if (!p) {
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p = kthread_create(watchdog, (void *)(unsigned long)cpu, "watchdog/%d", cpu);
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if (IS_ERR(p)) {
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printk(KERN_ERR "softlockup watchdog for %i failed\n", cpu);
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return PTR_ERR(p);
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}
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kthread_bind(p, cpu);
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per_cpu(watchdog_touch_ts, cpu) = 0;
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per_cpu(softlockup_watchdog, cpu) = p;
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wake_up_process(p);
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}
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/* if any cpu succeeds, watchdog is considered enabled for the system */
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watchdog_enabled = 1;
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return 0;
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}
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static void watchdog_disable(int cpu)
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{
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struct task_struct *p = per_cpu(softlockup_watchdog, cpu);
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struct hrtimer *hrtimer = &per_cpu(watchdog_hrtimer, cpu);
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/*
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* cancel the timer first to stop incrementing the stats
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* and waking up the kthread
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*/
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hrtimer_cancel(hrtimer);
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/* disable the perf event */
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watchdog_nmi_disable(cpu);
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/* stop the watchdog thread */
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if (p) {
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per_cpu(softlockup_watchdog, cpu) = NULL;
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kthread_stop(p);
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}
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}
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|
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static void watchdog_enable_all_cpus(void)
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{
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int cpu;
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int result = 0;
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for_each_online_cpu(cpu)
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result += watchdog_enable(cpu);
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|
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if (result)
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printk(KERN_ERR "watchdog: failed to be enabled on some cpus\n");
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}
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|
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static void watchdog_disable_all_cpus(void)
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{
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int cpu;
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|
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if (no_watchdog)
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return;
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|
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for_each_online_cpu(cpu)
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watchdog_disable(cpu);
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|
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/* if all watchdogs are disabled, then they are disabled for the system */
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watchdog_enabled = 0;
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}
|
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|
|
|
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/* sysctl functions */
|
|
#ifdef CONFIG_SYSCTL
|
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/*
|
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* proc handler for /proc/sys/kernel/nmi_watchdog
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|
*/
|
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|
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int proc_dowatchdog_enabled(struct ctl_table *table, int write,
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void __user *buffer, size_t *length, loff_t *ppos)
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{
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proc_dointvec(table, write, buffer, length, ppos);
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|
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if (watchdog_enabled)
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watchdog_enable_all_cpus();
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else
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watchdog_disable_all_cpus();
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return 0;
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}
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|
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int proc_dowatchdog_thresh(struct ctl_table *table, int write,
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void __user *buffer,
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size_t *lenp, loff_t *ppos)
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{
|
|
return proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
}
|
|
#endif /* CONFIG_SYSCTL */
|
|
|
|
|
|
/*
|
|
* Create/destroy watchdog threads as CPUs come and go:
|
|
*/
|
|
static int __cpuinit
|
|
cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu)
|
|
{
|
|
int hotcpu = (unsigned long)hcpu;
|
|
int err = 0;
|
|
|
|
switch (action) {
|
|
case CPU_UP_PREPARE:
|
|
case CPU_UP_PREPARE_FROZEN:
|
|
err = watchdog_prepare_cpu(hotcpu);
|
|
break;
|
|
case CPU_ONLINE:
|
|
case CPU_ONLINE_FROZEN:
|
|
err = watchdog_enable(hotcpu);
|
|
break;
|
|
#ifdef CONFIG_HOTPLUG_CPU
|
|
case CPU_UP_CANCELED:
|
|
case CPU_UP_CANCELED_FROZEN:
|
|
watchdog_disable(hotcpu);
|
|
break;
|
|
case CPU_DEAD:
|
|
case CPU_DEAD_FROZEN:
|
|
watchdog_disable(hotcpu);
|
|
break;
|
|
#endif /* CONFIG_HOTPLUG_CPU */
|
|
}
|
|
return notifier_from_errno(err);
|
|
}
|
|
|
|
static struct notifier_block __cpuinitdata cpu_nfb = {
|
|
.notifier_call = cpu_callback
|
|
};
|
|
|
|
void __init lockup_detector_init(void)
|
|
{
|
|
void *cpu = (void *)(long)smp_processor_id();
|
|
int err;
|
|
|
|
if (no_watchdog)
|
|
return;
|
|
|
|
err = cpu_callback(&cpu_nfb, CPU_UP_PREPARE, cpu);
|
|
WARN_ON(notifier_to_errno(err));
|
|
|
|
cpu_callback(&cpu_nfb, CPU_ONLINE, cpu);
|
|
register_cpu_notifier(&cpu_nfb);
|
|
|
|
return;
|
|
}
|