linux-kernel - Re: [PATCH RFC 06/19] slab: introduce percpu sheaves bootstrap

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Message-ID: <5153dc10-c041-4283-9722-b93a76c44a20@suse.cz>
Date: Mon, 15 Dec 2025 16:20:20 +0100
From: Vlastimil Babka <vbabka@...e.cz>
To: Hao Li <hao.li@...ux.dev>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 Christoph Lameter <cl@...two.org>, David Rientjes <rientjes@...gle.com>,
 Roman Gushchin <roman.gushchin@...ux.dev>, Harry Yoo <harry.yoo@...cle.com>,
 Uladzislau Rezki <urezki@...il.com>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>,
 Suren Baghdasaryan <surenb@...gle.com>,
 Sebastian Andrzej Siewior <bigeasy@...utronix.de>,
 Alexei Starovoitov <ast@...nel.org>, linux-mm@...ck.org,
 linux-kernel@...r.kernel.org, linux-rt-devel@...ts.linux.dev,
 bpf@...r.kernel.org, kasan-dev@...glegroups.com
Subject: Re: [PATCH RFC 06/19] slab: introduce percpu sheaves bootstrap

On 12/15/25 13:17, Hao Li wrote:
> On Thu, Oct 23, 2025 at 03:52:28PM +0200, Vlastimil Babka wrote:
>> @@ -8608,12 +8656,10 @@ int do_kmem_cache_create(struct kmem_cache *s, const char *name,
>>  
>>  	set_cpu_partial(s);
>>  
>> -	if (s->sheaf_capacity) {
>> -		s->cpu_sheaves = alloc_percpu(struct slub_percpu_sheaves);
>> -		if (!s->cpu_sheaves) {
>> -			err = -ENOMEM;
>> -			goto out;
>> -		}
>> +	s->cpu_sheaves = alloc_percpu(struct slub_percpu_sheaves);
> 
> After this change, all SLUB caches enable cpu_sheaves; therefore,
> slab_unmergeable() will always return 1.
> 
> int slab_unmergeable(struct kmem_cache *s)
> {
> ...
> 	if (s->cpu_sheaves)
> 		return 1;
> ...
> }
> 
> Maybe we need to update slab_unmergeable() accordingly..

Yes, I meant to do that but seems I forgot. Thanks for the reminder!

>> +	if (!s->cpu_sheaves) {
>> +		err = -ENOMEM;
>> +		goto out;
>>  	}
>>  
>>  #ifdef CONFIG_NUMA
>> @@ -8632,11 +8678,9 @@ int do_kmem_cache_create(struct kmem_cache *s, const char *name,
>>  	if (!alloc_kmem_cache_cpus(s))
>>  		goto out;
>>  
>> -	if (s->cpu_sheaves) {
>> -		err = init_percpu_sheaves(s);
>> -		if (err)
>> -			goto out;
>> -	}
>> +	err = init_percpu_sheaves(s);
>> +	if (err)
>> +		goto out;
>>  
>>  	err = 0;
>>  
>> 
>> -- 
>> 2.51.1
>>