Messages in this thread | | | Date | Tue, 25 Jun 2019 03:11:18 +0200 | From | Frederic Weisbecker <> | Subject | Re: [PATCH v2] kernel/isolation: Assert that a housekeeping CPU comes up at boot time |
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On Tue, Jun 25, 2019 at 10:17:20AM +1000, Nicholas Piggin wrote: > +static int __init housekeeping_verify_smp(void) > +{ > + int cpu; > + > + if (!housekeeping_flags) > + return 0; > + > + /* > + * Early housekeeping setup is done before CPUs come up, and there are > + * a range of options scattered around that can restrict which CPUs > + * come up. It is possible to pass in a combination of housekeeping > + * and SMP arguments that result in housekeeping assigned to an > + * offline CPU. > + * > + * Check that condition here after SMP comes up, and give a useful > + * error message rather than an obscure non deterministic crash or > + * hang later. > + */ > + for_each_online_cpu(cpu) { > + if (cpumask_test_cpu(cpu, housekeeping_mask)) > + return 0; > + } > + panic("Housekeeping: nohz_full= or isolcpus= resulted in no online CPUs for housekeeping.\n");
Ok let's keep the panic. But let's simplify and spare long iterations off boot load:
if (!cpumask_intersects(cpu_online_mask, housekeeping_mask)) panic(...);
Thanks.
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