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

[Harry Yoo <harry.yoo@oracle.com>]

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?

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

-- 
Cheers,
Harry / Hyeonggon