Re: [RFC PATCH v3 2/3] powerpc: Only set numa node information for present cpus at boottime

[Nishanth Aravamudan <nacc@linux.vnet.ibm.com>]

On 27.08.2014 [17:34:00 +0800], Li Zhong wrote:
> As Nish suggested, it makes more sense to init the numa node informatiion
> for present cpus at boottime, which could also avoid WARN_ON(1) in
> numa_setup_cpu().
> 
> With this change, we also need to change the smp_prepare_cpus() to set up
> numa information only on present cpus.
> 
> For those possible, but not present cpus, their numa information
> will be set up after they are started, as the original code did before commit
> 2fabf084b6ad.
> 
> Cc: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
> Cc: Nathan Fontenot <nfont@linux.vnet.ibm.com>
> Signed-off-by: Li Zhong <zhong@linux.vnet.ibm.com>

Acked-by: Nishanth Aravamudan <nacc@linux.vnet.ibm.com>
> ---
>  arch/powerpc/kernel/smp.c | 10 ++++++++--
>  arch/powerpc/mm/numa.c    |  2 +-
>  2 files changed, 9 insertions(+), 3 deletions(-)
> 
> diff --git a/arch/powerpc/kernel/smp.c b/arch/powerpc/kernel/smp.c
> index a0738af..dc0e774 100644
> --- a/arch/powerpc/kernel/smp.c
> +++ b/arch/powerpc/kernel/smp.c
> @@ -379,8 +379,11 @@ void __init smp_prepare_cpus(unsigned int max_cpus)
>  		/*
>  		 * numa_node_id() works after this.
>  		 */
> -		set_cpu_numa_node(cpu, numa_cpu_lookup_table[cpu]);
> -		set_cpu_numa_mem(cpu, local_memory_node(numa_cpu_lookup_table[cpu]));
> +		if (cpu_present(cpu)) {
> +			set_cpu_numa_node(cpu, numa_cpu_lookup_table[cpu]);
> +			set_cpu_numa_mem(cpu,
> +				local_memory_node(numa_cpu_lookup_table[cpu]));
> +		}
>  	}
> 
>  	cpumask_set_cpu(boot_cpuid, cpu_sibling_mask(boot_cpuid));
> @@ -728,6 +731,9 @@ void start_secondary(void *unused)
>  	}
>  	traverse_core_siblings(cpu, true);
> 
> +	set_numa_node(numa_cpu_lookup_table[cpu]);
> +	set_numa_mem(local_memory_node(numa_cpu_lookup_table[cpu]));
> +
>  	smp_wmb();
>  	notify_cpu_starting(cpu);
>  	set_cpu_online(cpu, true);
> diff --git a/arch/powerpc/mm/numa.c b/arch/powerpc/mm/numa.c
> index 9918c02..3a9061e 100644
> --- a/arch/powerpc/mm/numa.c
> +++ b/arch/powerpc/mm/numa.c
> @@ -1127,7 +1127,7 @@ void __init do_init_bootmem(void)
>  	 * even before we online them, so that we can use cpu_to_{node,mem}
>  	 * early in boot, cf. smp_prepare_cpus().
>  	 */
> -	for_each_possible_cpu(cpu) {
> +	for_each_present_cpu(cpu) {
>  		numa_setup_cpu((unsigned long)cpu);
>  	}
>  }
> -- 
> 1.9.1
>