Re: [PATCH] LoongArch: Fix cpu hotplug issue

[maobibo]

Huacai,

On 2024/10/14 下午3:05, Huacai Chen wrote:
> Hi, Bibo,
>
> I'm a little confused, so please correct me if I'm wrong.
>
> On Mon, Oct 14, 2024 at 2:33 PM Bibo Mao <maobibo@xxxxxxxxxxx> wrote:
> > On LoongArch system, there are two places to set cpu numa node. One
> > is in arch specified function smp_prepare_boot_cpu(), the other is
> > in generic function early_numa_node_init(). The latter will overwrite
> > the numa node information.
> >
> > However for hot-added cpu, cpu_logical_map() fails to its physical
> > cpuid at beginning since it is not enabled in ACPI MADT table. So
> > function early_cpu_to_node() also fails to get its numa node for
> > hot-added cpu, and generic function early_numa_node_init() will
> > overwrite incorrect numa node.
> For hot-added cpus, we will call acpi_map_cpu() -->
> acpi_map_cpu2node() --> set_cpuid_to_node(), and set_cpuid_to_node()
> operates on __cpuid_to_node[]. So I think early_cpu_to_node() should
> be correct?

__cpuid_to_node[] is correct which is physical cpuid to numa node, 
however cpu_logical_map(cpu) is not set. It fails to get physical cpuid
from logic cpu.

int early_cpu_to_node(int cpu)
{
        int physid = cpu_logical_map(cpu);

<<<<<<<<<<< Here physid is -1.

        if (physid < 0)
                return NUMA_NO_NODE;

        return __cpuid_to_node[physid];
}

Regards
Bibo Mao
> Huacai
>
> > Here static array __cpu_to_node and api set_early_cpu_to_node()
> > is added, so that early_cpu_to_node is consistent with function
> > cpu_to_node() for hot-added cpu.
> >
> > Signed-off-by: Bibo Mao <maobibo@xxxxxxxxxxx>
> > ---
> >   arch/loongarch/include/asm/numa.h |  2 ++
> >   arch/loongarch/kernel/numa.c      | 10 +++++++++-
> >   arch/loongarch/kernel/smp.c       |  1 +
> >   3 files changed, 12 insertions(+), 1 deletion(-)
> >
> > diff --git a/arch/loongarch/include/asm/numa.h b/arch/loongarch/include/asm/numa.h
> > index b5f9de9f102e..e8e6fcfb006a 100644
> > --- a/arch/loongarch/include/asm/numa.h
> > +++ b/arch/loongarch/include/asm/numa.h
> > @@ -50,6 +50,7 @@ static inline void set_cpuid_to_node(int cpuid, s16 node)
> >   }
> >
> >   extern int early_cpu_to_node(int cpu);
> > +extern void set_early_cpu_to_node(int cpu, s16 node);
> >
> >   #else
> >
> > @@ -57,6 +58,7 @@ static inline void early_numa_add_cpu(int cpuid, s16 node)    { }
> >   static inline void numa_add_cpu(unsigned int cpu)              { }
> >   static inline void numa_remove_cpu(unsigned int cpu)           { }
> >   static inline void set_cpuid_to_node(int cpuid, s16 node)      { }
> > +static inline void set_early_cpu_to_node(int cpu, s16 node)    { }
> >
> >   static inline int early_cpu_to_node(int cpu)
> >   {
> > diff --git a/arch/loongarch/kernel/numa.c b/arch/loongarch/kernel/numa.c
> > index 84fe7f854820..62508aace644 100644
> > --- a/arch/loongarch/kernel/numa.c
> > +++ b/arch/loongarch/kernel/numa.c
> > @@ -34,6 +34,9 @@ static struct numa_meminfo numa_meminfo;
> >   cpumask_t cpus_on_node[MAX_NUMNODES];
> >   cpumask_t phys_cpus_on_node[MAX_NUMNODES];
> >   EXPORT_SYMBOL(cpus_on_node);
> > +static s16 __cpu_to_node[NR_CPUS] = {
> > +       [0 ... CONFIG_NR_CPUS - 1] = NUMA_NO_NODE
> > +};
> >
> >   /*
> >    * apicid, cpu, node mappings
> > @@ -117,11 +120,16 @@ int early_cpu_to_node(int cpu)
> >          int physid = cpu_logical_map(cpu);
> >
> >          if (physid < 0)
> > -               return NUMA_NO_NODE;
> > +               return __cpu_to_node[cpu];
> >
> >          return __cpuid_to_node[physid];
> >   }
> >
> > +void set_early_cpu_to_node(int cpu, s16 node)
> > +{
> > +       __cpu_to_node[cpu] = node;
> > +}
> > +
> >   void __init early_numa_add_cpu(int cpuid, s16 node)
> >   {
> >          int cpu = __cpu_number_map[cpuid];
> > diff --git a/arch/loongarch/kernel/smp.c b/arch/loongarch/kernel/smp.c
> > index 9afc2d8b3414..998668be858c 100644
> > --- a/arch/loongarch/kernel/smp.c
> > +++ b/arch/loongarch/kernel/smp.c
> > @@ -512,6 +512,7 @@ void __init smp_prepare_boot_cpu(void)
> >                          set_cpu_numa_node(cpu, node);
> >                  else {
> >                          set_cpu_numa_node(cpu, rr_node);
> > +                       set_early_cpu_to_node(cpu, rr_node);
> >                          rr_node = next_node_in(rr_node, node_online_map);
> >                  }
> >          }
> >
> > base-commit: 6485cf5ea253d40d507cd71253c9568c5470cd27
> > --
> > 2.39.3