commit 3d89e5478bf550a50c99e93adf659369798263b0 upstream. Commit: e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug") ... set rq->prev_* to 0 after a CPU hotplug comes back, in order to fix the case where (after CPU hotplug) steal time is smaller than rq->prev_steal_time. However, this should never happen. Steal time was only smaller because of the KVM-specific bug fixed by the previous patch. Worse, the previous patch triggers a bug on CPU hot-unplug/plug operation: because rq->prev_steal_time is cleared, all of the CPU's past steal time will be accounted again on hot-plug. Since the root cause has been fixed, we can just revert commit e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug"). Signed-off-by: Wanpeng Li <wanpeng.li@xxxxxxxxxxx> Signed-off-by: Peter Zijlstra (Intel) <peterz@xxxxxxxxxxxxx> Acked-by: Paolo Bonzini <pbonzini@xxxxxxxxxx> Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx> Cc: Linus Torvalds <torvalds@xxxxxxxxxxxxxxxxxxxx> Cc: Mike Galbraith <efault@xxxxxx> Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx> Cc: Radim Krčmář <rkrcmar@xxxxxxxxxx> Cc: Rik van Riel <riel@xxxxxxxxxx> Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx> Fixes: 'commit e9532e69b8d1 ("sched/cputime: Fix steal time accounting vs. CPU hotplug")' Link: http://lkml.kernel.org/r/1465813966-3116-3-git-send-email-wanpeng.li@xxxxxxxxxxx Signed-off-by: Ingo Molnar <mingo@xxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> Signed-off-by: Andres Oportus <andresoportus@xxxxxxxxxx> --- kernel/sched/core.c | 1 - kernel/sched/sched.h | 13 ------------- 2 files changed, 14 deletions(-) diff --git a/kernel/sched/core.c b/kernel/sched/core.c index c436426..b103b9c 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -5553,7 +5553,6 @@ migration_call(struct notifier_block *nfb, unsigned long action, void *hcpu) case CPU_UP_PREPARE: rq->calc_load_update = calc_load_update; - account_reset_rq(rq); break; case CPU_ONLINE: diff --git a/kernel/sched/sched.h b/kernel/sched/sched.h index 4e5db65..55d92a1 100644 --- a/kernel/sched/sched.h +++ b/kernel/sched/sched.h @@ -1770,16 +1770,3 @@ static inline u64 irq_time_read(int cpu) } #endif /* CONFIG_64BIT */ #endif /* CONFIG_IRQ_TIME_ACCOUNTING */ - -static inline void account_reset_rq(struct rq *rq) -{ -#ifdef CONFIG_IRQ_TIME_ACCOUNTING - rq->prev_irq_time = 0; -#endif -#ifdef CONFIG_PARAVIRT - rq->prev_steal_time = 0; -#endif -#ifdef CONFIG_PARAVIRT_TIME_ACCOUNTING - rq->prev_steal_time_rq = 0; -#endif -} -- 1.9.1