On Wed, Nov 23, 2022 at 02:53:43PM +0100, Vlastimil Babka wrote:
> On 11/21/22 18:11, Vlastimil Babka wrote:
> > Distinguishing kmalloc(__GFP_RECLAIMABLE) can help against fragmentation
> > by grouping pages by mobility, but on tiny systems the extra memory
> > overhead of separate set of kmalloc-rcl caches will probably be worse,
> > and mobility grouping likely disabled anyway.
> >
> > Thus with CONFIG_SLUB_TINY, don't create kmalloc-rcl caches and use the
> > regular ones.
> >
> > Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
>
> Fixed up in response to lkp report for a MEMCG_KMEM+SLUB_TINY combo:
> ---8<---
> From c1ec0b924850a2863d061f316615d596176f15bb Mon Sep 17 00:00:00 2001
> From: Vlastimil Babka <vbabka@xxxxxxx>
> Date: Tue, 15 Nov 2022 18:19:28 +0100
> Subject: [PATCH 06/12] mm, slub: don't create kmalloc-rcl caches with
> CONFIG_SLUB_TINY
>
> Distinguishing kmalloc(__GFP_RECLAIMABLE) can help against fragmentation
> by grouping pages by mobility, but on tiny systems the extra memory
> overhead of separate set of kmalloc-rcl caches will probably be worse,
> and mobility grouping likely disabled anyway.
>
> Thus with CONFIG_SLUB_TINY, don't create kmalloc-rcl caches and use the
> regular ones.
>
> Signed-off-by: Vlastimil Babka <vbabka@xxxxxxx>
> ---
> include/linux/slab.h | 9 +++++++--
> mm/slab_common.c | 10 ++++++++--
> 2 files changed, 15 insertions(+), 4 deletions(-)
>
> diff --git a/include/linux/slab.h b/include/linux/slab.h
> index 45efc6c553b8..ae2d19ec8467 100644
> --- a/include/linux/slab.h
> +++ b/include/linux/slab.h
> @@ -336,12 +336,17 @@ enum kmalloc_cache_type {
> #endif
> #ifndef CONFIG_MEMCG_KMEM
> KMALLOC_CGROUP = KMALLOC_NORMAL,
> -#else
> - KMALLOC_CGROUP,
> #endif
> +#ifdef CONFIG_SLUB_TINY
> + KMALLOC_RECLAIM = KMALLOC_NORMAL,
> +#else
> KMALLOC_RECLAIM,
> +#endif
> #ifdef CONFIG_ZONE_DMA
> KMALLOC_DMA,
> +#endif
> +#ifdef CONFIG_MEMCG_KMEM
> + KMALLOC_CGROUP,
> #endif
> NR_KMALLOC_TYPES
> };
Can you please elaborate what the lkp report was about
and how you fixed it? I'm not getting what the problem of previous
version is.
> diff --git a/mm/slab_common.c b/mm/slab_common.c
> index a8cb5de255fc..907d52963806 100644
> --- a/mm/slab_common.c
> +++ b/mm/slab_common.c
> @@ -770,10 +770,16 @@ EXPORT_SYMBOL(kmalloc_size_roundup);
> #define KMALLOC_CGROUP_NAME(sz)
> #endif
>
> +#ifndef CONFIG_SLUB_TINY
> +#define KMALLOC_RCL_NAME(sz) .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #sz,
> +#else
> +#define KMALLOC_RCL_NAME(sz)
> +#endif
> +
> #define INIT_KMALLOC_INFO(__size, __short_size) \
> { \
> .name[KMALLOC_NORMAL] = "kmalloc-" #__short_size, \
> - .name[KMALLOC_RECLAIM] = "kmalloc-rcl-" #__short_size, \
> + KMALLOC_RCL_NAME(__short_size) \
> KMALLOC_CGROUP_NAME(__short_size) \
> KMALLOC_DMA_NAME(__short_size) \
> .size = __size, \
> @@ -859,7 +865,7 @@ void __init setup_kmalloc_cache_index_table(void)
> static void __init
> new_kmalloc_cache(int idx, enum kmalloc_cache_type type, slab_flags_t flags)
> {
> - if (type == KMALLOC_RECLAIM) {
> + if ((KMALLOC_RECLAIM != KMALLOC_NORMAL) && (type == KMALLOC_RECLAIM)) {
> flags |= SLAB_RECLAIM_ACCOUNT;
> } else if (IS_ENABLED(CONFIG_MEMCG_KMEM) && (type == KMALLOC_CGROUP)) {
> if (mem_cgroup_kmem_disabled()) {
> --
> 2.38.1
>
Otherwise looks fine to me.
--
Thanks,
Hyeonggon
