Re: [PATCH RFC 0/8] replace CONFIG_SLUB_TINY with a slab_tiny boot parameter

[Harry Yoo <harry@kernel.org>]

On Wed, Sep 23, 2026 at 05:45:05PM +0200, Vlastimil Babka (SUSE) wrote:
> To sum up, after this series:
> 
> - CONFIG_SLUB_TINY is a deprecated option that has no interaction with
>   other options and only controls the default behavior.
> 
> - New slab_tiny boot parameter controls the functionality (and can
>   override CONFIG_SLUB_TINY in both directions).
>
> - slab_debug=N can effectively achieve most of slab_tiny and on a
>   per-cache basic

Allowing "slab_tiny=0" doesn't make much sense given that
CONFIG_SLUB_TINY is deprecated anyway. I was assuming specifying
"slab_tiny" would enable it and not specifying it would disable it
unless CONFIG_SLUB_TINY is set.

Also it's bit confusing to have multiple ways to achieve the same thing.
Is there a reason why we can't interpret "slab_debug=N" as
"slab_tiny_enabled = 1" internally and drop "slab_tiny" boot parameter?

> - the implementation is simpler with many ifdefs removed
> 
> [1] https://lore.kernel.org/all/CAHk-=wh-k04MsoEC0SGKff2Snm6bBF_e+0pHOKwaWv4umZ_SnQ@mail.gmail.com/
> 
> Signed-off-by: Vlastimil Babka (SUSE) <vbabka@kernel.org>
> ---
> Vlastimil Babka (SUSE) (8):
>       mm, slab: refactor slab_min/max_order handling
>       mm, slab: introduce slab_debug=N
>       mm, slab: rework KMALLOC_RECLAIM handling of SLUB_TINY
>       mm, slab: make SLUB_TINY handling dynamic for sizing decisions
>       mm, slab: convert CONFIG_SLUB_TINY checks to kmem_cache_debug()
>       mm, slab: remove remaining compile-time checks for CONFIG_SLUB_TINY
>       mm, slab: add slab_tiny boot param
>       mm, slab: deprecate CONFIG_SLUB_TINY and reduce its Kconfig effects
> 
>  Documentation/admin-guide/kernel-parameters.txt |   4 +
>  Documentation/admin-guide/mm/slab.rst           |  18 ++-
>  include/linux/slab.h                            |  17 +--
>  lib/Kconfig.kasan                               |   2 +-
>  mm/Kconfig                                      |  16 ++-
>  mm/Kconfig.debug                                |   2 +-
>  mm/slab.h                                       |  32 +++--
>  mm/slab_common.c                                |  12 +-
>  mm/slub.c                                       | 149 +++++++++++-------------
>  9 files changed, 120 insertions(+), 132 deletions(-)
> ---
> base-commit: b4218126d498275444f315b0ed4cef6add6beabc
> change-id: 20260911-slub_tiny_rework-8f2634dd17a7
> 

-- 
Cheers,
Harry / Hyeonggon