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Because at this time the rq->clock_update_flags of other CPUs may be RQCF_UPDATED. Some call trace reports: Call Trace 1: __schedule+0x61c/0x11d0 schedule+0x5d/0xd0 worker_thread+0xb5/0x380 ? preempt_count_add+0x56/0xa0 ? rescuer_thread+0x310/0x310 kthread+0xe6/0x110 ? kthread_complete_and_exit+0x20/0x20 ret_from_fork+0x1f/0x30 Call Trace 2: __schedule+0x91d/0x11d0 schedule+0x5d/0xd0 exit_to_user_mode_prepare+0xe5/0x1e0 syscall_exit_to_user_mode+0x17/0x30 do_syscall_64+0x40/0x90 entry_SYSCALL_64_after_hwframe+0x63/0xcd Call Trace 3: __sched_core_tick+0x27/0x40 scheduler_tick+0x1be/0x270 ? tick_sched_handle.isra.18+0x60/0x60 update_process_times+0x6a/0x90 tick_sched_handle.isra.18+0x1f/0x60 tick_sched_timer+0x47/0x80 __hrtimer_run_queues+0x10a/0x280 hrtimer_interrupt+0x10b/0x240 __sysvec_apic_timer_interrupt+0x70/0x160 sysvec_apic_timer_interrupt+0x9a/0xd0 asm_sysvec_apic_timer_interrupt+0x16/0x20 Steps to reproduce: 1. Enable CONFIG_SCHED_DEBUG and CONFIG_SCHED_CORE when compiling the kernel 2. echo 1 > /sys/kernel/debug/clear_warn_once echo "WARN_DOUBLE_CLOCK" > /sys/kernel/debug/sched/features 3. Run the linux/tools/testing/selftests/sched/cs_prctl_test test Signed-off-by: Hao Jia --- kernel/sched/core.c | 5 ++++- kernel/sched/core_sched.c | 4 +++- kernel/sched/sched.h | 10 +++++++++- 3 files changed, 16 insertions(+), 3 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index daff72f00385..fcf5e4faec34 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5951,6 +5951,7 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) rq->core->core_cookie = 0UL; if (rq->core->core_forceidle_count) { if (!core_clock_updated) { + rq_clock_clear_update(rq->core); update_rq_clock(rq->core); core_clock_updated = true; } @@ -6007,8 +6008,10 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf) * pick_next_task(). If the current cpu is not the core, * the core may also have been updated above. */ - if (i != cpu && (rq_i != rq->core || !core_clock_updated)) + if (i != cpu && (rq_i != rq->core || !core_clock_updated)) { + rq_clock_clear_update(rq_i); update_rq_clock(rq_i); + } p = rq_i->core_pick = pick_task(rq_i); if (!max || prio_less(max, p, fi_before)) diff --git a/kernel/sched/core_sched.c b/kernel/sched/core_sched.c index a57fd8f27498..70a6f36fd830 100644 --- a/kernel/sched/core_sched.c +++ b/kernel/sched/core_sched.c @@ -291,8 +291,10 @@ void __sched_core_tick(struct rq *rq) if (!rq->core->core_forceidle_count) return; - if (rq != rq->core) + if (rq != rq->core) { + rq_clock_clear_update(rq->core); update_rq_clock(rq->core); + } __sched_core_account_forceidle(rq); } diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index a4a20046e586..1a2c40c413c2 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -2544,8 +2544,16 @@ static inline void double_rq_clock_clear_update(struct rq *rq1, struct rq *rq2) rq2->clock_update_flags &= (RQCF_REQ_SKIP|RQCF_ACT_SKIP); #endif } -#else + +#ifdef CONFIG_SCHED_CORE +static inline void rq_clock_clear_update(struct rq *rq) +{ + rq->clock_update_flags &= (RQCF_REQ_SKIP|RQCF_ACT_SKIP); +} +#endif +#else /* CONFIG_SCHED_DEBUG */ static inline void double_rq_clock_clear_update(struct rq *rq1, struct rq *rq2) {} +static inline void rq_clock_clear_update(struct rq *rq) {} #endif #ifdef CONFIG_SMP