Re: [PATCH 2/2] mm/slab: free a bit in enum objexts_flags

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

On Mon, Feb 09, 2026 at 09:10:13PM +0900, Harry Yoo wrote:
> Since kfree() now supports freeing objects allocated with
> kmalloc_nolock(), free one bit in enum object_flags.
> 
> Signed-off-by: Harry Yoo <harry.yoo@oracle.com>

Oops, looks like I forgot to add Alexei's ack, and...

> ---
>  include/linux/memcontrol.h |  3 +--
>  mm/slub.c                  | 12 ++----------
>  2 files changed, 3 insertions(+), 12 deletions(-)
> 
> diff --git a/mm/slub.c b/mm/slub.c
> index 63b03fd62ca7..33d2cae8f939 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -2213,10 +2211,7 @@ int alloc_slab_obj_exts(struct slab *slab, struct kmem_cache *s,
>  		 * objcg vector should be reused.
>  		 */
>  		mark_objexts_empty(vec);
> -		if (unlikely(!allow_spin))
> -			kfree_nolock(vec);
> -		else
> -			kfree(vec);
> +		kfree(vec);
>  		return 0;

Oh Harry, no.

We still need to check allow_spin in this case.

Just because you can free objects allocated from kmalloc_nolock() with
kfree() doesn't mean you can call kfree() when allow_spin == false.

I'll respin v2.

>  	} else if (cmpxchg(&slab->obj_exts, old_exts, new_exts) != old_exts) {
>  		/* Retry if a racing thread changed slab->obj_exts from under us. */

-- 
Cheers,
Harry / Hyeonggon