Messages in this thread Patch in this message | | | From | Petr Mladek <> | Subject | [PATCH 1/3] watchdog/softlockup: Remove obsolete check of last reported task | Date | Thu, 24 Oct 2019 13:49:26 +0200 |
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The commit 9cf57731b63e37ed995 ("watchdog/softlockup: Replace "watchdog/%u" threads with cpu_stop_work") caused that the watchdog is reliably touched during a task switch.
As a result the check for a unnoticed task switch is not longer needed. And the commit b1a8de1f534337b398c7778 ("softlockup: make detector be aware of task switch of processes hogging cpu") can be reverted.
Signed-off-by: Petr Mladek <pmladek@suse.com> --- kernel/watchdog.c | 18 +----------------- 1 file changed, 1 insertion(+), 17 deletions(-)
diff --git a/kernel/watchdog.c b/kernel/watchdog.c index f41334ef0971..b7e2046380cf 100644 --- a/kernel/watchdog.c +++ b/kernel/watchdog.c @@ -174,7 +174,6 @@ static DEFINE_PER_CPU(bool, softlockup_touch_sync); static DEFINE_PER_CPU(bool, soft_watchdog_warn); static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts); static DEFINE_PER_CPU(unsigned long, soft_lockup_hrtimer_cnt); -static DEFINE_PER_CPU(struct task_struct *, softlockup_task_ptr_saved); static DEFINE_PER_CPU(unsigned long, hrtimer_interrupts_saved); static unsigned long soft_lockup_nmi_warn; @@ -416,22 +415,8 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) return HRTIMER_RESTART; /* only warn once */ - if (__this_cpu_read(soft_watchdog_warn) == true) { - /* - * When multiple processes are causing softlockups the - * softlockup detector only warns on the first one - * because the code relies on a full quiet cycle to - * re-arm. The second process prevents the quiet cycle - * and never gets reported. Use task pointers to detect - * this. - */ - if (__this_cpu_read(softlockup_task_ptr_saved) != - current) { - __this_cpu_write(soft_watchdog_warn, false); - __touch_watchdog(); - } + if (__this_cpu_read(soft_watchdog_warn) == true) return HRTIMER_RESTART; - } if (softlockup_all_cpu_backtrace) { /* Prevent multiple soft-lockup reports if one cpu is already @@ -447,7 +432,6 @@ static enum hrtimer_restart watchdog_timer_fn(struct hrtimer *hrtimer) pr_emerg("BUG: soft lockup - CPU#%d stuck for %us! [%s:%d]\n", smp_processor_id(), duration, current->comm, task_pid_nr(current)); - __this_cpu_write(softlockup_task_ptr_saved, current); print_modules(); print_irqtrace_events(current); if (regs) -- 2.16.4
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