Messages in this thread | | | Date | Sat, 22 Feb 2020 18:51:51 +0100 | From | Borislav Petkov <> | Subject | Re: [PATCH] x86/mce/therm_throt: Handle case where throttle_active_work() is called on behalf of an offline CPU |
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On Sat, Feb 22, 2020 at 08:24:32AM -0800, Srinivas Pandruvada wrote: > During cpu-hotplug test with CONFIG_PREEMPTION and CONFIG_DEBUG_PREEMPT > enabled, Chris reported error: > > BUG: using smp_processor_id() in preemptible [00000000] code: kworker/1:0/17 > caller is throttle_active_work+0x12/0x280 > > Here throttle_active_work() is a work queue callback scheduled with > schedule_delayed_work_on(). This will not cause this error for the use > of smp_processor_id() under normal conditions as there is a check for > "current->nr_cpus_allowed == 1". > But when the target CPU is offline the workqueue becomes unbound. > Then the work queue callback can be scheduled on another CPU and the > error is printed for the use of smp_processor_id() in preemptible context.
So what's wrong with simply doing:
if (cpu_is_offline(this_cpu)) return;
?
You don't need to run the callback on an offlined CPU anyway...
-- Regards/Gruss, Boris.
https://people.kernel.org/tglx/notes-about-netiquette
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