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https://github.com/torvalds/linux
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257bf89d84
housekeeping_setup() checks cpumask_intersects(present, online) to ensure that the kernel will have at least one housekeeping CPU after smp_init(), but this doesn't work if the maxcpus= kernel parameter limits the number of processors available after bootup. For example, a kernel with "maxcpus=2 nohz_full=0-2" parameters crashes at boot time on a virtual machine with 4 CPUs. Change housekeeping_setup() to use cpumask_first_and() and check that the returned CPU number is valid and less than setup_max_cpus. 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. Signed-off-by: Oleg Nesterov <oleg@redhat.com> Signed-off-by: Thomas Gleixner <tglx@linutronix.de> Signed-off-by: Ingo Molnar <mingo@kernel.org> Reviewed-by: Phil Auld <pauld@redhat.com> Acked-by: Frederic Weisbecker <frederic@kernel.org> Link: https://lore.kernel.org/r/20240413141746.GA10008@redhat.com |
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| .. | ||
| autogroup.c | ||
| autogroup.h | ||
| build_policy.c | ||
| build_utility.c | ||
| clock.c | ||
| completion.c | ||
| core.c | ||
| core_sched.c | ||
| cpuacct.c | ||
| cpudeadline.c | ||
| cpudeadline.h | ||
| cpufreq.c | ||
| cpufreq_schedutil.c | ||
| cpupri.c | ||
| cpupri.h | ||
| cputime.c | ||
| deadline.c | ||
| debug.c | ||
| fair.c | ||
| features.h | ||
| idle.c | ||
| isolation.c | ||
| loadavg.c | ||
| Makefile | ||
| membarrier.c | ||
| pelt.c | ||
| pelt.h | ||
| psi.c | ||
| rt.c | ||
| sched-pelt.h | ||
| sched.h | ||
| smp.h | ||
| stats.c | ||
| stats.h | ||
| stop_task.c | ||
| swait.c | ||
| topology.c | ||
| wait.c | ||
| wait_bit.c | ||