Re: [PATCH v3 12/17] x86/crash: Use num_possible_cpus() for elfcorehdr size

[Jinjie Ruan <ruanjinjie@huawei.com>]

在 2026/9/2 14:14, Sourabh Jain 写道:
> Hello Jinjie,
> 
> This patch makes the below patch redundant..
> https://lore.kernel.org/all/20260826073527.21487-2-
> ionut.nechita@windriver.com/
> 
> I suggest dropping the first patch from the above series and including
> the second patch from that series in this patch series with the updated
> comment.

Agreed. This approach makes sense to me.

I will update it in v4.

> 
> - Sourabh Jain
> 
> 
> On 26/08/26 14:55, Jinjie Ruan wrote:
>> Use num_possible_cpus() instead of CONFIG_NR_CPUS to calculate the
>> elfcorehdr buffer size, matching what crash_prepare_elf64_headers()
>> already uses for the actual header content.
>>
>> This avoids over-allocation when the system has fewer possible CPUs
>> than the compile-time limit, and aligns x86 with PowerPC.
>>
>> Signed-off-by: Jinjie Ruan <ruanjinjie@huawei.com>
>> ---
>>   arch/x86/kernel/crash.c | 6 +++---
>>   1 file changed, 3 insertions(+), 3 deletions(-)
>>
>> diff --git a/arch/x86/kernel/crash.c b/arch/x86/kernel/crash.c
>> index a3bf786286d4..afe2aea19f47 100644
>> --- a/arch/x86/kernel/crash.c
>> +++ b/arch/x86/kernel/crash.c
>> @@ -369,9 +369,9 @@ int crash_load_segments(struct kimage *image)
>>        * maximum CPUs and maximum memory ranges.
>>        */
>>       if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
>> -        pnum = 2 + CONFIG_NR_CPUS + CONFIG_CRASH_MAX_MEMORY_RANGES;
>> +        pnum = 2 + num_possible_cpus() + CONFIG_CRASH_MAX_MEMORY_RANGES;
>>       else
>> -        pnum += 2 + CONFIG_NR_CPUS;
>> +        pnum += 2 + num_possible_cpus();
>>         if (pnum < (unsigned long)PN_XNUM) {
>>           kbuf.memsz = elf64_phdr_size(pnum);
>> @@ -429,7 +429,7 @@ unsigned int arch_crash_get_elfcorehdr_size(void)
>>       unsigned int sz;
>>         /* kernel_map, VMCOREINFO and maximum CPUs */
>> -    sz = 2 + CONFIG_NR_CPUS;
>> +    sz = 2 + num_possible_cpus();
>>       if (IS_ENABLED(CONFIG_MEMORY_HOTPLUG))
>>           sz += CONFIG_CRASH_MAX_MEMORY_RANGES;
>>       sz *= sizeof(Elf64_Phdr);
>