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SubjectRe: [PATCH 07/12] mm, slab: ignore SLAB_RECLAIM_ACCOUNT with CONFIG_SLUB_TINY
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On 11/21/22 18:11, Vlastimil Babka wrote:
> SLAB_RECLAIM_ACCOUNT caches allocate their slab pages with
> __GFP_RECLAIMABLE and can help against fragmentation by grouping pages
> by mobility, but on tiny systems mobility grouping is likely disabled
> anyway and ignoring SLAB_RECLAIM_ACCOUNT might instead lead to merging
> of caches that are made incompatible just by the flag.
>
> Thus with CONFIG_SLUB_TINY, make SLAB_RECLAIM_ACCOUNT ineffective.
>
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
> ---
> include/linux/slab.h | 4 ++++
> 1 file changed, 4 insertions(+)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 3ce9474c90ab..1cbbda03ad06 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -129,7 +129,11 @@
>
> /* The following flags affect the page allocator grouping pages by mobility */
> /* Objects are reclaimable */
> +#ifndef CONFIG_SLUB_TINY
> #define SLAB_RECLAIM_ACCOUNT ((slab_flags_t __force)0x00020000U)
> +#else
> +#define SLAB_RECLAIM_ACCOUNT 0

Updating the last line above to:
#define SLAB_RECLAIM_ACCOUNT ((slab_flags_t __force)0)

In response to:
https://lore.kernel.org/all/202211280441.yCEecX9z-lkp@intel.com/

Yeah it probably means that the other pre-existing flag variants that
#define to 0 should be also adjusted to avoid these issues, but not as part
of this series.

> +#endif
> #define SLAB_TEMPORARY SLAB_RECLAIM_ACCOUNT /* Objects are short-lived */
>
> /*

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