linux-kernel - RE: [PATCH 1/4] mm/slub: remove the check of !kmem_cache_has_cpu

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Message-ID: 
 <PH0PR11MB5192481170379F35BF292E82EC3D2@PH0PR11MB5192.namprd11.prod.outlook.com>
Date: Wed, 3 Apr 2024 00:10:42 +0000
From: "Song, Xiongwei" <Xiongwei.Song@...driver.com>
To: Vlastimil Babka <vbabka@...e.cz>,
        "rientjes@...gle.com"
	<rientjes@...gle.com>,
        "cl@...ux.com" <cl@...ux.com>,
        "penberg@...nel.org"
	<penberg@...nel.org>,
        "iamjoonsoo.kim@....com" <iamjoonsoo.kim@....com>,
        "akpm@...ux-foundation.org" <akpm@...ux-foundation.org>,
        "roman.gushchin@...ux.dev" <roman.gushchin@...ux.dev>,
        "42.hyeyoo@...il.com"
	<42.hyeyoo@...il.com>
CC: "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org"
	<linux-kernel@...r.kernel.org>,
        "chengming.zhou@...ux.dev"
	<chengming.zhou@...ux.dev>
Subject: RE: [PATCH 1/4] mm/slub: remove the check of
 !kmem_cache_has_cpu_partial()

> 
> On 3/31/24 4:19 AM, xiongwei.song@...driver.com wrote:
> > From: Xiongwei Song <xiongwei.song@...driver.com>
> >
> > The check of !kmem_cache_has_cpu_partial(s) with
> > CONFIG_SLUB_CPU_PARTIAL enabled here is always false. We have known the
> > result by calling kmem_cacke_debug(). Here we can remove it.
> 
> Could we be more obvious. We have already checked kmem_cache_debug() earlier
> and if it was true, the we either continued or broke from the loop so we
> can't reach this code in that case and don't need to check
> kmem_cache_debug() as part of kmem_cache_has_cpu_partial() again.

Ok, looks better. Will update.

Thanks,
Xiongwei

> 
> > Signed-off-by: Xiongwei Song <xiongwei.song@...driver.com>
> > ---
> >  mm/slub.c | 3 +--
> >  1 file changed, 1 insertion(+), 2 deletions(-)
> >
> > diff --git a/mm/slub.c b/mm/slub.c
> > index 1bb2a93cf7b6..059922044a4f 100644
> > --- a/mm/slub.c
> > +++ b/mm/slub.c
> > @@ -2610,8 +2610,7 @@ static struct slab *get_partial_node(struct kmem_cache *s,
> >                       partial_slabs++;
> >               }
> >  #ifdef CONFIG_SLUB_CPU_PARTIAL
> > -             if (!kmem_cache_has_cpu_partial(s)
> > -                     || partial_slabs > s->cpu_partial_slabs / 2)
> > +             if (partial_slabs > s->cpu_partial_slabs / 2)
> >                       break;
> >  #else
> >               break;