Messages in this thread | | | Date | Sun, 28 Apr 2024 10:13:18 +0200 | From | Ingo Molnar <> | Subject | Re: [tip: sched/urgent] sched/isolation: Fix boot crash when maxcpus < first housekeeping CPU |
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* tip-bot2 for Oleg Nesterov <tip-bot2@linutronix.de> wrote:
> Another corner case is "nohz_full=0" on a machine with a single CPU or with > the maxcpus=1 kernel argument. In this case non_housekeeping_mask is empty > and tick_nohz_full_setup() makes no sense. And indeed, the kernel hits the > WARN_ON(tick_nohz_full_running) in tick_sched_do_timer(). > > And how should the kernel interpret the "nohz_full=" parameter? It should > be silently ignored, but currently cpulist_parse() happily returns the > empty cpumask and this leads to the same problem. > > Change housekeeping_setup() to check cpumask_empty(non_housekeeping_mask) > and do nothing in this case.
So arguably the user meant NOHZ_FULL to be turned off - but it is de-facto already turned off by the fact that there's only a single CPU available, right?
Thanks,
Ingo
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