From bf5015a50f1fdb248b48405b67cae24dc02605d6 Mon Sep 17 00:00:00 2001 From: Juri Lelli Date: Thu, 24 May 2018 17:29:36 +0200 Subject: sched/topology: Clarify root domain(s) debug string When scheduler debug is enabled, building scheduling domains outputs information about how the domains are laid out and to which root domain each CPU (or sets of CPUs) belongs, e.g.: CPU0 attaching sched-domain(s): domain-0: span=0-5 level=MC groups: 0:{ span=0 }, 1:{ span=1 }, 2:{ span=2 }, 3:{ span=3 }, 4:{ span=4 }, 5:{ span=5 } CPU1 attaching sched-domain(s): domain-0: span=0-5 level=MC groups: 1:{ span=1 }, 2:{ span=2 }, 3:{ span=3 }, 4:{ span=4 }, 5:{ span=5 }, 0:{ span=0 } [...] span: 0-5 (max cpu_capacity = 1024) The fact that latest line refers to CPUs 0-5 root domain doesn't however look immediately obvious to me: one might wonder why span 0-5 is reported "again". Make it more clear by adding "root domain" to it, as to end with the following: CPU0 attaching sched-domain(s): domain-0: span=0-5 level=MC groups: 0:{ span=0 }, 1:{ span=1 }, 2:{ span=2 }, 3:{ span=3 }, 4:{ span=4 }, 5:{ span=5 } CPU1 attaching sched-domain(s): domain-0: span=0-5 level=MC groups: 1:{ span=1 }, 2:{ span=2 }, 3:{ span=3 }, 4:{ span=4 }, 5:{ span=5 }, 0:{ span=0 } [...] root domain span: 0-5 (max cpu_capacity = 1024) Signed-off-by: Juri Lelli Signed-off-by: Peter Zijlstra (Intel) Cc: Dietmar Eggemann Cc: Linus Torvalds Cc: Patrick Bellasi Cc: Peter Zijlstra Cc: Thomas Gleixner Link: http://lkml.kernel.org/r/20180524152936.17611-1-juri.lelli@redhat.com Signed-off-by: Ingo Molnar --- kernel/sched/topology.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'kernel') diff --git a/kernel/sched/topology.c b/kernel/sched/topology.c index 64cc564f5255..61a1125c1ae4 100644 --- a/kernel/sched/topology.c +++ b/kernel/sched/topology.c @@ -1708,7 +1708,7 @@ build_sched_domains(const struct cpumask *cpu_map, struct sched_domain_attr *att rcu_read_unlock(); if (rq && sched_debug_enabled) { - pr_info("span: %*pbl (max cpu_capacity = %lu)\n", + pr_info("root domain span: %*pbl (max cpu_capacity = %lu)\n", cpumask_pr_args(cpu_map), rq->rd->max_cpu_capacity); } -- cgit v1.2.3 From b1f5b378e126133521df668379249fb8265121f1 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Fri, 4 May 2018 11:11:42 +0200 Subject: kthread: Allow kthread_park() on a parked kthread The following commit: 85f1abe0019f ("kthread, sched/wait: Fix kthread_parkme() completion issue") added a WARN() in the case where we call kthread_park() on an already parked thread, because the old code wasn't doing the right thing there and it wasn't at all clear that would happen. It turns out, this does in fact happen, so we have to deal with it. Instead of potentially returning early, also wait for the completion. This does however mean we have to use complete_all() and re-initialize the completion on re-use. Reported-by: LKP Tested-by: Meelis Roos Signed-off-by: Peter Zijlstra (Intel) Cc: Linus Torvalds Cc: Peter Zijlstra Cc: kernel test robot Cc: wfg@linux.intel.com Cc: Thomas Gleixner Fixes: 85f1abe0019f ("kthread, sched/wait: Fix kthread_parkme() completion issue") Link: http://lkml.kernel.org/r/20180504091142.GI12235@hirez.programming.kicks-ass.net Signed-off-by: Ingo Molnar --- kernel/kthread.c | 6 ++---- 1 file changed, 2 insertions(+), 4 deletions(-) (limited to 'kernel') diff --git a/kernel/kthread.c b/kernel/kthread.c index 2017a39ab490..481951bf091d 100644 --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -193,7 +193,7 @@ EXPORT_SYMBOL_GPL(kthread_parkme); void kthread_park_complete(struct task_struct *k) { - complete(&to_kthread(k)->parked); + complete_all(&to_kthread(k)->parked); } static int kthread(void *_create) @@ -459,6 +459,7 @@ void kthread_unpark(struct task_struct *k) if (test_bit(KTHREAD_IS_PER_CPU, &kthread->flags)) __kthread_bind(k, kthread->cpu, TASK_PARKED); + reinit_completion(&kthread->parked); clear_bit(KTHREAD_SHOULD_PARK, &kthread->flags); wake_up_state(k, TASK_PARKED); } @@ -483,9 +484,6 @@ int kthread_park(struct task_struct *k) if (WARN_ON(k->flags & PF_EXITING)) return -ENOSYS; - if (WARN_ON_ONCE(test_bit(KTHREAD_SHOULD_PARK, &kthread->flags))) - return -EBUSY; - set_bit(KTHREAD_SHOULD_PARK, &kthread->flags); if (k != current) { wake_up_process(k); -- cgit v1.2.3