Re: [PATCH v1] mm/slub: Genericize x86-specific cmpxchg16b comment

[Tiezhu Yang <yangtiezhu@loongson.cn>]

On 2026/11/2 下午10:49, Harry Yoo wrote:
> On Mon, Nov 02, 2026 at 04:27:30PM +0800, Tiezhu Yang wrote:
>> The kmalloc_nolock() infrastructure relies on slab caches with double-word
>> atomic cmpxchg capabilities (__CMPXCHG_DOUBLE). The current inline comment
>> in __kmalloc_nolock_noprof() uses 'cmpxchg16b' as the prerequisite hardware
>> capability.

...

>> diff --git a/mm/slub.c b/mm/slub.c
>> index 45e077c7526c..216bc6b5d776 100644
>> --- a/mm/slub.c
>> +++ b/mm/slub.c
>> @@ -5589,8 +5589,8 @@ static void *__kmalloc_nolock_noprof(DECL_TOKEN_PARAMS(size, token), gfp_t gfp_f
>>   	if (!(s->flags & __CMPXCHG_DOUBLE) && !kmem_cache_debug(s))
>>   		/*
>>   		 * kmalloc_nolock() is not supported on architectures that
>> -		 * don't implement cmpxchg16b and thus need slab_lock()
>> -		 * which could be preempted by a nmi.
>> +		 * don't implement 128-bit atomic cmpxchg and thus need
>> +		 * slab_lock() which could be preempted by a nmi.
> 
> maybe "double-width atomic cmpxchg" is more accurate considering
> e.g.) x86-32 implements cmpxchg8b?

OK. Using "double-width atomic cmpxchg" is much more accurate
as it perfectly covers both 32-bit and 64-bit platforms, and
aligns well with the __CMPXCHG_DOUBLE flag.

I will send out v2 with this update later if no more comments.

Thanks,
Tiezhu