From: Wanpeng Li <[email protected]> Interrupt exit is the place to stop the tick: it happens after all events happening before and during the irq which are liable to update the dependency on the tick occurred. However, tick_nohz_stop_sched_tick() try to stop the full tick instead of bailing out in advance.
As a result: WARNING: CPU: 3 PID: 31 at kernel/irq_work.c:124 irq_work_needs_cpu+0x86/0x90 CPU: 3 PID: 31 Comm: migration/3 Not tainted 4.8.0-rc5+ #46 Call Trace: <IRQ> [<ffffffffb94477c9>] dump_stack+0x99/0xd0 [<ffffffffb908d581>] __warn+0xd1/0xf0 [<ffffffffb908d66d>] warn_slowpath_null+0x1d/0x20 [<ffffffffb91a7446>] irq_work_needs_cpu+0x86/0x90 [<ffffffffb912cbed>] tick_nohz_stop_sched_tick+0x2ad/0x430 [<ffffffffb912d75e>] ? tick_nohz_irq_exit+0x10e/0x150 [<ffffffffb906de05>] ? kvm_clock_read+0x25/0x30 [<ffffffffb912d75e>] tick_nohz_irq_exit+0x10e/0x150 [<ffffffffb9094a31>] irq_exit+0x81/0xf0 [<ffffffffb98ca4cc>] do_IRQ+0x6c/0x120 [<ffffffffb98c83d6>] common_interrupt+0x96/0x96 <EOI> [<ffffffffb9153fb2>] ? multi_cpu_stop+0xa2/0x160 [<ffffffffb9153f10>] ? cpu_stop_park+0x40/0x40 [<ffffffffb9153e44>] cpu_stopper_thread+0x74/0x100 [<ffffffffb90b7e77>] smpboot_thread_fn+0x117/0x1d0 [<ffffffffb90b7d60>] ? sort_range+0x30/0x30 [<ffffffffb90b4111>] kthread+0x101/0x120 [<ffffffffb90dea6d>] ? complete+0x1d/0x50 [<ffffffffb98c7c8f>] ret_from_fork+0x1f/0x40 [<ffffffffb90b4010>] ? kthread_create_on_node+0x250/0x250 Commit f7ea0fd639c2c4 (tick: Don't invoke tick_nohz_stop_sched_tick() if the cpu is offline) fixes stop idle tick for offline cpu, this patch adds the similar method to fix the intention to stop full tick for offline cpu. Cc: Thomas Gleixner <[email protected]> Cc: Ingo Molnar <[email protected]> Cc: Peter Zijlstra <[email protected]> Cc: Frederic Weisbecker <[email protected]> Signed-off-by: Wanpeng Li <[email protected]> --- kernel/time/tick-sched.c | 7 +++++-- 1 file changed, 5 insertions(+), 2 deletions(-) diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 2ec7c00..3bcb61b 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -186,10 +186,13 @@ static bool check_tick_dependency(atomic_t *dep) return false; } -static bool can_stop_full_tick(struct tick_sched *ts) +static bool can_stop_full_tick(int cpu, struct tick_sched *ts) { WARN_ON_ONCE(!irqs_disabled()); + if (unlikely(!cpu_online(cpu))) + return false; + if (check_tick_dependency(&tick_dep_mask)) return false; @@ -843,7 +846,7 @@ static void tick_nohz_full_update_tick(struct tick_sched *ts) if (!ts->tick_stopped && ts->nohz_mode == NOHZ_MODE_INACTIVE) return; - if (can_stop_full_tick(ts)) + if (can_stop_full_tick(cpu, ts)) tick_nohz_stop_sched_tick(ts, ktime_get(), cpu); else if (ts->tick_stopped) tick_nohz_restart_sched_tick(ts, ktime_get()); -- 1.9.1
