fe4ba3c343
Change the default behavior of watchdog so it only runs on the housekeeping cores when nohz_full is enabled at build and boot time. Allow modifying the set of cores the watchdog is currently running on with a new kernel.watchdog_cpumask sysctl. In the current system, the watchdog subsystem runs a periodic timer that schedules the watchdog kthread to run. However, nohz_full cores are designed to allow userspace application code running on those cores to have 100% access to the CPU. So the watchdog system prevents the nohz_full application code from being able to run the way it wants to, thus the motivation to suppress the watchdog on nohz_full cores, which this patchset provides by default. However, if we disable the watchdog globally, then the housekeeping cores can't benefit from the watchdog functionality. So we allow disabling it only on some cores. See Documentation/lockup-watchdogs.txt for more information. [jhubbard@nvidia.com: fix a watchdog crash in some configurations] Signed-off-by: Chris Metcalf <cmetcalf@ezchip.com> Acked-by: Don Zickus <dzickus@redhat.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Ulrich Obergfell <uobergfe@redhat.com> Cc: Thomas Gleixner <tglx@linutronix.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: John Hubbard <jhubbard@nvidia.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
90 lines
2.3 KiB
C
90 lines
2.3 KiB
C
/*
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* linux/include/linux/nmi.h
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*/
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#ifndef LINUX_NMI_H
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#define LINUX_NMI_H
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#include <linux/sched.h>
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#include <asm/irq.h>
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/**
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* touch_nmi_watchdog - restart NMI watchdog timeout.
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*
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* If the architecture supports the NMI watchdog, touch_nmi_watchdog()
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* may be used to reset the timeout - for code which intentionally
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* disables interrupts for a long time. This call is stateless.
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*/
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#if defined(CONFIG_HAVE_NMI_WATCHDOG) || defined(CONFIG_HARDLOCKUP_DETECTOR)
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#include <asm/nmi.h>
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extern void touch_nmi_watchdog(void);
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#else
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static inline void touch_nmi_watchdog(void)
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{
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touch_softlockup_watchdog();
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}
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#endif
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#if defined(CONFIG_HARDLOCKUP_DETECTOR)
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extern void hardlockup_detector_disable(void);
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#else
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static inline void hardlockup_detector_disable(void)
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{
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}
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#endif
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/*
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* Create trigger_all_cpu_backtrace() out of the arch-provided
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* base function. Return whether such support was available,
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* to allow calling code to fall back to some other mechanism:
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*/
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#ifdef arch_trigger_all_cpu_backtrace
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static inline bool trigger_all_cpu_backtrace(void)
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{
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arch_trigger_all_cpu_backtrace(true);
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return true;
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}
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static inline bool trigger_allbutself_cpu_backtrace(void)
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{
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arch_trigger_all_cpu_backtrace(false);
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return true;
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}
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#else
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static inline bool trigger_all_cpu_backtrace(void)
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{
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return false;
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}
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static inline bool trigger_allbutself_cpu_backtrace(void)
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{
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return false;
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}
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#endif
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#ifdef CONFIG_LOCKUP_DETECTOR
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int hw_nmi_is_cpu_stuck(struct pt_regs *);
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u64 hw_nmi_get_sample_period(int watchdog_thresh);
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extern int nmi_watchdog_enabled;
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extern int soft_watchdog_enabled;
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extern int watchdog_user_enabled;
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extern int watchdog_thresh;
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extern unsigned long *watchdog_cpumask_bits;
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extern int sysctl_softlockup_all_cpu_backtrace;
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struct ctl_table;
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extern int proc_watchdog(struct ctl_table *, int ,
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void __user *, size_t *, loff_t *);
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extern int proc_nmi_watchdog(struct ctl_table *, int ,
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void __user *, size_t *, loff_t *);
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extern int proc_soft_watchdog(struct ctl_table *, int ,
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void __user *, size_t *, loff_t *);
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extern int proc_watchdog_thresh(struct ctl_table *, int ,
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void __user *, size_t *, loff_t *);
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extern int proc_watchdog_cpumask(struct ctl_table *, int,
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void __user *, size_t *, loff_t *);
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#endif
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#ifdef CONFIG_HAVE_ACPI_APEI_NMI
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#include <asm/nmi.h>
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#endif
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#endif
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