Re: [PATCH] LoongArch: Fix cpu hotplug issue

[Huacai Chen]

On Mon, Oct 14, 2024 at 3:21 PM maobibo <maobibo@xxxxxxxxxxx> wrote:
>
> 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.
early_cpu_to_node() is not supposed to be called after boot, and if it
is really needed, I think a better solution is:

diff --git a/arch/loongarch/kernel/acpi.c b/arch/loongarch/kernel/acpi.c
index f1a74b80f22c..998cf45fd3b7 100644
--- a/arch/loongarch/kernel/acpi.c
+++ b/arch/loongarch/kernel/acpi.c
@@ -311,6 +311,8 @@ static int __ref acpi_map_cpu2node(acpi_handle
handle, int cpu, int physid)

        nid = acpi_get_node(handle);
        if (nid != NUMA_NO_NODE) {
+               __cpu_number_map[physid] = cpu;
+               __cpu_logical_map[cpu] = physid;
                set_cpuid_to_node(physid, nid);
                node_set(nid, numa_nodes_parsed);
                set_cpu_numa_node(cpu, nid);

Huacai

>
>          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
> >>
> >>
>
>