Re: [PATCH V1 1/2] mm/slab: factor out slab_args_unmergeable()

[Vlastimil Babka <vbabka@suse.cz>]

On 1/27/26 17:42, Harry Yoo wrote:
> On Tue, Jan 27, 2026 at 05:35:50PM +0100, Vlastimil Babka wrote:
>> On 1/27/26 11:31, Harry Yoo wrote:
>> > slab_mergeable() determines whether a slab cache can be merged, but it
>> > should not be used when the cache is not fully created yet.
>> > 
>> > Extract the pre-cache-creation mergeability checks into
>> > slab_args_unmergeable(), which evaluates kmem_cache_args, slab flags,
>> > and slab_nomerge to determine if a cache will be mergeable before it is
>> > created.
>> > 
>> > Signed-off-by: Harry Yoo <harry.yoo@oracle.com>
>> > ---
>> >  mm/slab_common.c | 28 ++++++++++++++++++----------
>> >  1 file changed, 18 insertions(+), 10 deletions(-)
>> > 
>> > diff --git a/mm/slab_common.c b/mm/slab_common.c
>> > index 2e80d323f550..904414c3ebb8 100644
>> > --- a/mm/slab_common.c
>> > +++ b/mm/slab_common.c
>> > @@ -174,24 +174,32 @@ int slab_unmergeable(struct kmem_cache *s)
>> >  	return 0;
>> >  }
>> >  
>> > -static struct kmem_cache *find_mergeable(unsigned int size, slab_flags_t flags,
>> > -		const char *name, struct kmem_cache_args *args)
>> > +static bool slab_args_unmergeable(struct kmem_cache_args *args,
>> > +				  slab_flags_t flags)
>> >  {
>> > -	struct kmem_cache *s;
>> > -	unsigned int align;
>> > -
>> >  	if (slab_nomerge)
>> > -		return NULL;
>> > +		return true;
>> 
>> I think this still logically belongs to find_mergeable() and not here, so
>> moved there. Agreed?
> 
> But then patch 2/2 should be modified to check slab_nomerge then?

Yeah I would do that as well,

> And even slab_unmergeable() does slab_nomerge check, so perhaps it's
> more consistent to do it in slab_args_unmergeable().

But this is true so I'll leave both as you did, thanks!