Re: [PATCH] mm/slab: Fix undefined init_cache_node_node() for NUMA and !SMP

From: Geert Uytterhoeven <geert@linux-m68k.org>
To: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>
Cc: Dave Hansen <dave.hansen@linux.intel.com>,
	Arnd Bergmann <arnd@arndb.de>, Christoph Lameter <cl@linux.com>,
	Pekka Enberg <penberg@kernel.org>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Vlastimil Babka <vbabka@suse.cz>,
	Roman Gushchin <roman.gushchin@linux.dev>,
	Hyeonggon Yoo <42.hyeyoo@gmail.com>,
	linux-mm@kvack.org, linux-sh@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Randy Dunlap <rdunlap@infradead.org>
Subject: Re: [PATCH] mm/slab: Fix undefined init_cache_node_node() for NUMA and !SMP
Date: Tue, 21 Mar 2023 09:50:03 +0100	[thread overview]
Message-ID: <CAMuHMdUJ+o4qf056XgLHtkoPnqL+Nk4jZhQ7zntKS0_1dzYAEg@mail.gmail.com> (raw)
In-Reply-To: <fac6b2c757166df891d60bd00524af7e7d30fe78.camel@physik.fu-berlin.de>

Hi Adrian,

On Tue, Mar 21, 2023 at 9:47 AM John Paul Adrian Glaubitz
<glaubitz@physik.fu-berlin.de> wrote:
> On Tue, 2023-03-21 at 09:30 +0100, Geert Uytterhoeven wrote:
> > sh/migor_defconfig:
> >
> >     mm/slab.c: In function ‘slab_memory_callback’:
> >     mm/slab.c:1127:23: error: implicit declaration of function ‘init_cache_node_node’; did you mean ‘drain_cache_node_node’? [-Werror=implicit-function-declaration]
> >      1127 |                 ret = init_cache_node_node(nid);
> >         |                       ^~~~~~~~~~~~~~~~~~~~
> >         |                       drain_cache_node_node
> >
> > The #ifdef condition protecting the definition of init_cache_node_node()
> > no longer matches the conditions protecting the (multiple) users.
> >
> > Fix this by syncing the conditions.
> >
> > Fixes: 76af6a054da40553 ("mm/migrate: add CPU hotplug to demotion #ifdef")
> > Reported-by: Randy Dunlap <rdunlap@infradead.org>
> > Link: https://lore.kernel.org/r/b5bdea22-ed2f-3187-6efe-0c72330270a4@infradead.org
> > Signed-off-by: Geert Uytterhoeven <geert+renesas@glider.be>
> > ---
> >  mm/slab.c | 2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> >
> > diff --git a/mm/slab.c b/mm/slab.c
> > index ba454246ee13dd4d..de1523a78f2e7367 100644
> > --- a/mm/slab.c
> > +++ b/mm/slab.c
> > @@ -839,7 +839,7 @@ static int init_cache_node(struct kmem_cache *cachep, int node, gfp_t gfp)
> >       return 0;
> >  }
> >
> > -#if (defined(CONFIG_NUMA) && defined(CONFIG_MEMORY_HOTPLUG)) || defined(CONFIG_SMP)
> > +#if defined(CONFIG_NUMA) || defined(CONFIG_SMP)
> >  /*
> >   * Allocates and initializes node for a node on each slab cache, used for
> >   * either memory or cpu hotplug.  If memory is being hot-added, the kmem_cache_node
>
> FWIW, the other #ifdef starting at drain_cache_node_node() closes with "#endif /* CONFIG_NUMA */",
> while this #ifdef just ends with "#endif". Just in case you want to make this consistent.

I guess that's fine, as init_cache_node_node() is a small function.
#endif comments are typically used when the start and end markers
do not fit on your (80x25 ;-) screen.

> Reviewed-by: John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds