Messages in this thread | | | Date | Fri, 16 May 2014 17:56:10 +0800 | From | Lai Jiangshan <> | Subject | Re: workqueue: WARN at at kernel/workqueue.c:2176 |
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On 05/16/2014 05:35 PM, Peter Zijlstra wrote: > On Fri, May 16, 2014 at 11:50:42AM +0800, Lai Jiangshan wrote: >> After debugging, I found the hotlug-in cpu is atctive but !online in this case. >> the problem was introduced by 5fbd036b. >> Some code assumes that any cpu in cpu_active_mask is also online, but 5fbd036b breaks >> this assumption, so the corresponding code with this assumption should be changed too. > > Good find, and yes it does that. > >> The following patch is just a workaround. After it is applied, the above WARNING >> is gone, but I can't hit the wq problem that you found. > > Seeing how the entirety of hotplug is basically duct tape and twigs, the > below isn't that bad.
I think we need to find a more grace solution...
> >> --- >> diff --git a/kernel/cpu.c b/kernel/cpu.c >> index a9e710e..253a129 100644 >> --- a/kernel/cpu.c >> +++ b/kernel/cpu.c >> @@ -726,9 +726,10 @@ void set_cpu_present(unsigned int cpu, bool present) >> >> void set_cpu_online(unsigned int cpu, bool online) >> { >> - if (online) >> + if (online) { >> cpumask_set_cpu(cpu, to_cpumask(cpu_online_bits)); >> - else >> + cpumask_set_cpu(cpu, to_cpumask(cpu_active_bits)); >> + } else >> cpumask_clear_cpu(cpu, to_cpumask(cpu_online_bits)); >> } >> >> diff --git a/kernel/sched/core.c b/kernel/sched/core.c >> index 268a45e..c1a712d 100644 >> --- a/kernel/sched/core.c >> +++ b/kernel/sched/core.c >> @@ -5043,7 +5043,6 @@ static int sched_cpu_active(struct notifier_block *nfb, >> unsigned long action, void *hcpu) >> { >> switch (action & ~CPU_TASKS_FROZEN) { >> - case CPU_STARTING: >> case CPU_DOWN_FAILED: >> set_cpu_active((long)hcpu, true); >> return NOTIFY_OK;
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