Re: [PATCH v3 13/21] slab: remove defer_deactivate_slab()

Harry Yoo
2026-01-20T05:48:03Z

On Fri, Jan 16, 2026 at 03:40:33PM +0100, Vlastimil Babka wrote:
> There are no more cpu slabs so we don't need their deferred
> deactivation. The function is now only used from places where we
> allocate a new slab but then can't spin on node list_lock to put it on
> the partial list. Instead of the deferred action we can free it directly
> via __free_slab(), we just need to tell it to use _nolock() freeing of
> the underlying pages and take care of the accounting.
>
> Since free_frozen_pages_nolock() variant does not yet exist for code
> outside of the page allocator, create it as a trivial wrapper for
> __free_frozen_pages(..., FPI_TRYLOCK).
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> mm/internal.h | 1 +
> mm/page_alloc.c | 5 +++++
> mm/slab.h | 8 +-------
> mm/slub.c | 56 ++++++++++++++++++++------------------------------------
> 4 files changed, 27 insertions(+), 43 deletions(-)
>
> index b08e775dc4cb..33f218c0e8d6 100644
> --- a/mm/slub.c
> +++ b/mm/slub.c
> @@ -3260,7 +3260,7 @@ static struct slab *new_slab(struct kmem_cache *s, gfp_t flags, int node)
> flags & (GFP_RECLAIM_MASK | GFP_CONSTRAINT_MASK), node);
> }
>
> -static void __free_slab(struct kmem_cache *s, struct slab *slab)
> +static void __free_slab(struct kmem_cache *s, struct slab *slab, bool allow_spin)
> {
> struct page *page = slab_page(slab);
> int order = compound_order(page);
> @@ -3271,14 +3271,26 @@ static void __free_slab(struct kmem_cache *s, struct slab *slab)
> __ClearPageSlab(page);
> mm_account_reclaimed_pages(pages);
> unaccount_slab(slab, order, s);

As long as the slab is allocated with !allow_spin, it should be safe to
call unaccount_slab()->free_slab_obj_exts().

Looks good to me,
Reviewed-by: Harry Yoo <harry.yoo@oracle.com>

--
Cheers,
Harry / Hyeonggon