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Message-ID: <5c1e0199-24ce-50d2-1cbc-5c9949a17563@loongson.cn>
Date: Mon, 14 Oct 2024 16:01:27 +0800
From: maobibo <maobibo@...ngson.cn>
To: Huacai Chen <chenhuacai@...nel.org>
Cc: loongarch@...ts.linux.dev, linux-kernel@...r.kernel.org,
lixianglai@...ngson.cn, WANG Xuerui <kernel@...0n.name>
Subject: Re: [PATCH] LoongArch: Fix cpu hotplug issue
Huacai,
On 2024/10/14 下午3:39, Huacai Chen wrote:
> On Mon, Oct 14, 2024 at 3:21 PM maobibo <maobibo@...ngson.cn> 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@...ngson.cn> 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
Which calls early_cpu_to_node() after boot?
> 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;
This does not solve the problem. The above has been done in function
cpu = set_processor_mask(physid, ACPI_MADT_ENABLED);
static int set_processor_mask(u32 id, u32 flags)
{
...
if (flags & ACPI_MADT_ENABLED) {
num_processors++;
set_cpu_present(cpu, true);
__cpu_number_map[cpuid] = cpu;
__cpu_logical_map[cpu] = cpuid;
}
The problem is that
smp_prepare_boot_cpu(); /* arch-specific boot-cpu hooks */
<<<<<<<<<<<<<<<<
set_cpu_numa_node() is called in function smp_prepare_boot_cpu()
early_numa_node_init();
static void __init early_numa_node_init(void)
{
#ifdef CONFIG_USE_PERCPU_NUMA_NODE_ID
#ifndef cpu_to_node
int cpu;
/* The early_cpu_to_node() should be ready here. */
for_each_possible_cpu(cpu)
set_cpu_numa_node(cpu, early_cpu_to_node(cpu));
<<<<<<<<<<<<<<<<
* however here early_cpu_to_node is -1, so that cpu_to_node(cpu) will
always return -1 in late. *, which causes cpu hotadd problem.
Regards
Bibo Mao
> 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@...ngson.cn>
>>>> ---
>>>> 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
>>>>
>>>>
>>
>>
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